Large-DeformationFailureMechanismofCoal-FeederChamber...

Research ArticleLarge-Deformation Failure Mechanism of Coal-Feeder Chamberand Construction of Wall-Mounted Coal Bunker in UndergroundCoal Mine with Soft Swelling Floor Rocks

Xingkai Wang12 Wenbing Xie 1 Jianbiao Bai1 Shengguo Jing2 and Zhili Su2

1State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology Xuzhou 221116 China2School of Mines China University of Mining and Technology Xuzhou 221116 China

Correspondence should be addressed to Wenbing Xie 1692cumteducn

Received 21 March 2019 Revised 25 June 2019 Accepted 11 July 2019 Published 15 August 2019

Academic Editor Marco Corradi

Copyright copy 2019 XingkaiWang et al(is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

In traditional vertical coal bunker systems a coal-feeder chamber (CFC) must bear the whole weight of the bunker Howevermaintenance of CFCs within soft swelling floor rock is a challenge faced in underground coal mines Floor-heave control is acomplex problem and is still not well-solved Moreover there is no report on the construction of bunker without a CFC especiallyunder such weak floor-rock conditions Based on the serious CFC collapse case at Xiashijie mine China this work analyzed thedeformation characteristics main influencing factors and failuremechanisms of the CFC using a FLAC numerical model(e resultsindicate that the intrusion of water weakens the strength of the floor rock and causes significant expansive forces thus largedeformations and tensile failure occur first in the floor further causing shearing and tensile damage of the reinforced column andeven overall instability of the CFC (en a new wall-mounted coal bunker (WMCB) without building the CFC is proposed (eFLAC3D program was adopted to study the stability of the rocks surrounding the new bunker and an optimized reinforcementscheme was determined More importantly a self-bearing system which includes self-designed H-steel beams H-steel brackets andself-locking anchor cables was proposed and constructed to bear the whole weight of the bunker(e stability ofWMCBwas verifiedby a theoretical safety assessment and field test(e inventedWMCB could remain stable in spite of severe floor heave(is work canprovide helpful references for the construction of vertical bunkers without CFCs in coal mines with soft swelling floor rocks

1 Introduction

Raw coal produced at the working face in underground coalmines should be transported to the surface via a trans-portation system (Figure 1) which commonly includes a coalstrap transporting system in the longwall panel entry coal-storage bunker installed in the mining area conveyor belt inthe main haulage roadway coal bunker at the bottom of theshaft andmain shaft hoisting system It is clear that the storagebunker plays an indispensable role in coal transportation Inaddition the use of bunkers can reduce the effect of trans-portation interruptions and congestion [1 2] increase miningsystem availability [3] and improve transportation efficiency[4 5] (e bunker usually contains a bottom coal bunkerdistrict coal bunker section coal bunker ground bunker andtunnel bunker [4] all of which are generally divided into thethree forms horizontal vertical or inclined Overall

horizontal coal bunkers are used widely in the UnitedKingdom the United States Canada the former Soviet Unionetc However China one of the largest coal-mining countriesmainly researches and builds vertical coal bunkers [2]

Vertical bunkers have been used widely in China formany years Figure 2(a) shows the structure of a traditionalvertical bunker which includes the coal bunker body and thecoal-feeder chamber (CFC) which is constructed in the belthaulage roadway and bears the whole weight of the coal inthe bunker concrete silo and coal-feeder machine (e beltconveyors feed into the top of the bunker from eithervibrofeeders or variable-speed belt feeders loading out at thebottom [6] (us the stability of the CFC is crucial to ensurethe bunker works effectively Here coal bunker 214 couldnot be used owing to the severe collapse that occurred in theCFC even though it was repaired annually and many ef-fective measures were taken to improve the stability of the

HindawiAdvances in Civil EngineeringVolume 2019 Article ID 6519189 16 pageshttpsdoiorg10115520196519189

load-bearing structure of the CFC Figure 3 shows the largedeformation that occurred in the CFC

On the one hand much research has been devoted tostudy floor heave of chamber in coal mines [7ndash10] Nev-ertheless floor-heave control is a complex problem in un-derground coal mines the solution approaches arecommonly a combination of bolts anchor cables concreteand steel inverted arches and such construction techniquesare not only difficult to carry out in the field but the ap-plication effect is also poor On the other hand the study ofthe existing literature for coal bunker mainly focuses on (i)the optimum bunker size and location selection in un-derground coal mine conveyor systems [3 11] (ii) theconstruction of the coal bunker with a large diameter andvertical height [12 13] (iii) the optimization of methods of

safe construction under different geological conditions[14 15] (iv) the deterioration and collapse mechanism of thereinforced concrete bunker [16] (v) the curing technique ofblockage and fractures in the walls of the coal bunker body[17ndash19] and (vi) the maintenance of the coal bunker [20ndash22] (ose studies have made significant progress Howeverthere are no generally accepted cases applicable to con-struction of a new type of vertical coal bunker (Figure 2(b))without a CFC especially when the CFC of the traditionalcoal bunker could not be stable within weak floor rock

(is work used field surveys theoretical analysis labo-ratory tests and numerical simulation to analyze the mainfactors causing floor heave and the failure mechanism of theCFC (en a new coal bunker called a wall-mounted coalbunker (WMCB) without a CFC was invented and

Main haulage roadway

Coal bunker inmining area

Coal bunkernear sha

Mainsha

Longwallpanel no1Belt

hauling en

try

Figure 1 Coal transportation system in an underground coal mine

Belt haulageroadway

Coal bunkerbody

Coal-feeder chamber

Conveyors

Reinforced column

Foundations

Concrete

(a)

Conveyors

Roadways

Sandstone

Conveyors

Coal seam

Feeder

Concrete

(b)

Figure 2 Structure of (a) traditional vertical bunker 214 and (b) the new designed vertical bunker without CFC

2 Advances in Civil Engineering

designed and its key technological bases were investigated(is work focused on the construction method of a self-bearing system to transfer the entire weight borne by theCFC into the rock surrounding the coal bunker Finally thesecurity and the reliability of the new coal bunker werediscussed and it was implemented at Xiashijie coal mine

2 Background

21 Geological Conditions As shown in Figure 4 coalbunkers 214 and 3 (the new bunker) both vertical bunkersare located in the belt haulage roadway near the 953 sump inXiashijie coal mine Tongchuan Coal Mining Group Co LtdCoal bunker 214 is the original coal-storage bunker with aheight and diameter of 87m and 5m respectively It is notedthat coal bunker 214 is located entirely within coal seam 4-2 the two walls of CFC-surrounding rock are also part of coalseam 4-2 and the floor is mudstone Coal bunker 3 is builtto replace coal bunker 214 because of the latterrsquos repeatedfailures Coal bunker 3 is 5m in diameter and 15m in heightand its upper surrounding rock is coarse sandstone andsiltstone of which the thicknesses are 32m and 58m re-spectively(e lower part of the surrounding rock is coal seam4-2 with a thickness of 6m

22 CFC Failure Mechanism

221 Deformation Characteristics of the CFC (e CFCrsquosload-bearing structure is composed of the roof floor andside walls which are made of reinforced concrete Figure 3

shows the deformation and collapse of the CFC even thoughthe CFC was repaired twice and was recently reinforced by aconcrete column between the walls (e convergence of thechamber was measured by the crossing method [23] after thelatest repair (e deformation data collected after moni-toring for three months is shown in Figure 5 the roof-floorand wall-wall convergences in the CFC were 1632mm and218mm respectively Based on the onsite damage featuresand the deformation data the main deformation charac-teristics could be concluded as follows

(1) Large deformation of the floor the cumulative roof-floor convergence was much greater than the con-vergence of the walls in the CFC whereas the onsitedeformation shows that the roof subsidence was notobvious (less than 150mm) but severe floor heaveoccurred

(2) Collapse and failure constantly emerge after repair inthe CFC (especially the floor) the load-bearingstructure of the CFC could only remain stable for threemonths after repair this was mainly attributed to themudstone and clay materials of the immediate andhard floors respectively which are weak and soft innature and swell severely when water is encountered

222 Main Influencing Factors According to the in situsurvey and rock expansion experiments the main factorsinducing failure of the CFC are as follows

(1) (e swelling property of the CFC floor rocks theswelling properties of the mudstone and clay were

Roof was cracked

(a)

Roof was fractured

(b)

Roof

Reinforced column was inclined

(c)

Reinforced column was damaged

(d)

Figure 3 Collapse characteristics of the CFC in coal bunker 214 (a) (e roof was cracked (b) (e roof was fractured (c) (e reinforcedconcrete column was inclined (d) (e reinforced concrete column was damaged

Advances in Civil Engineering 3

verified by the laboratory tests ie the rock-expan-sion experiments [24] Figure 6 shows the dilatationalrate of the floor strata mudstone which increasedafter immersion in water for 2 h and then reached themaximum of 11700 με after 12 h Mineral-composi-tion analysis by electron microscope found that themudstone and clay rocks contain abundant mineralssuch as kaolinite montmorillonite and illite (eseminerals contained in the immediate floor and hardfloor account for as much as 82 and 85 re-spectively meaning that the floor rocks are liable toswelling which is not conducive to chamber stability

(2) (e rich supply of mine water under these geologicalconditions with a continuous supply of water fromthe seepage in the working-face goafs sump 953above and the productive water in the belt roadway(Figure 4) the swelling floor rocks would have lowerstrength and generate a significant expansive forcethus the concrete walls and floor of the chamberwere crushed after repair and reinforcement furthercausing the collapse in the chamber roof and in-ducing instability of the whole bearing structure

223 Influence of Water on the Floor Heave and Failure ofCFC Numerical simulation as a basic method is widely usedto determine the stresses or displacements in undergroundspaces [25 26] analyze the failure mechanism or stability

of engineering rock masses [13 27ndash30] optimize supportschemes for roadways [23] simulate experimental tests andverify the results thereof etc In this study the influencemechanism of water on floor heave and overall failure oc-curring in CFC was investigated by using a FLAC2D modelAccording to the main research of this work the simplifiedmodel was established as shown in Figure 7 (e boundaryconditions were set as follows a vertical stress of 98MPa wasapplied on the upper boundary of the numerical model tosimulate the overlying strata pressure (burial depth was nearly400m) a horizontal stress of 65Mpa was applied to the leftand right boundaries which were fixed in displacement in thenormal direction and the lower boundary was fixed in thevertical direction Based on the laboratory experiments and thedeformation information supplied by the coal mine theproperties of the coal and rock mass were determined byconsidering the HoekndashBrown failure criterion [31 32] Ad-ditionally a strain-softening constitutive model (Figure 8) wasselected For simplicity the friction angle remained unchangedwhile the cohesion of the rock mass gradually reduces to itsresidual value (01MPa) at which the plastic shear strainthreshold is 03 (e coal and rock physical and mechanicalparameters used in this model are shown in Table 1 Howeverthe intrusion of water weakens the mechanical connectionbetween rock and mineral particles which leads to the de-crease of the cohesion of rock mass and the weakening of thephysical andmechanical properties of rockmass [34] Figure 6shows that the swelling of the rock was not obvious after 30 hthus the mechanical parameters of the floor strata that wereimmersed in water for 36 h were measured by experimentaltests as given in Table 2 During numerical modeling the

214 coal bunkerAir

shaSealing wall 3 coal bunker(being excavated)

Coarse sandstone Siltstone

4-2 coal seam Belt haulage roadwayCarbon mudstone

Coal bunker 3 (being excavated)Coal seam 4ndash2Coal bunker 214

953 Sump

Figure 4 Geological cross section through coal bunkers 214 and 3

0

300

600

900

1200

1500

1800

0 20 40 60 80 100

Conv

erge

nce (

mm

)

Monitoring time (day)

Roof-floor convergenceWall-wall convergence

Figure 5 CFC deformation monitoring results

0

2

4

6

8

10

12

0 5 10 15 20 25 30

Dila

tatio

nal s

trai

n (times

10ndash3

)

Monitoring time (h)

Figure 6 Rock expansion experiment results


normal stiffness (kn) and shear stiffness (ks) of the interfacebetween the concrete and surrounding rock could be de-termined by the following equation [33]

kn ks 10K +(43)G

Δzmin1113890 1113891 (1)

where K and G are the bulk and shear moduli respectivelyand Δzmin is the smallest width of an adjoining zone in thenormal direction

To understand the influence of mine water on the failureof the CFC the distribution of both plastic zones (Figure 9)and displacement (Figure 10) in CFC were simulated underconditions with and without water Because mine water wasencountered the strength of the floor rocks decreased andswelling rock generated significant expansive forces and amuch larger ranging plastic zone appeared in the rocksurrounding the floor and walls in Figure 9(b) (the maxi-mum plastic zone reached 58m in the sides and floor) thanthat in Figure 9(a) (the maximum plastic zone only reached24m in the roof) Apparently tension and shearing damageoccurred in the roof (Figure 9(b)) which induced crackingand fracture of the roof (as shown in Figure 3) Moreoverthe bottom beam of the CFCwas almost completely in a state

of tensile failure and the reinforced column was mainlysubject to shearing and tension damage further causingsevere shear dilatancy (e collapse characteristics of theCFC were in line with the field photograph (Figure 3)

In addition comparison of displacement distributionswithout and with influence of water (Figure 10) showed thedisplacement of the chamber affected by mine water(maximum value of 643mm) was much greater than thatwithout the influence of water (maximum value of 24mm)More importantly without the influence of water the de-formation of the surrounding rock was mainly a result ofroof subsidence the floor and reinforced column de-formations were small However with the influence of watera large amount deformation appeared in floor and columnwhile the deformations of the roof and two sides were smallas shown in Figure 10(b) which was in good agreement within situ monitoring data (Figure 5) In summary the floorheave caused mainly by mine water is the underlying causeof the instability and repeated failure of concrete in CFC

Even though many measures were taken such as thedrainage of the mine water installation of U36 steel invertedarches and reinforcement of the bottom beams it was stilldifficult to control the floor heave (us coal bunker 214could not work properly

3 Key Techniques of the WMCB

As discussed previously severe floor heave is the main factorinducing instability of the CFC under this geological con-dition and no solution has been proven to be an effectivereinforcement method to maintain the traditional coalbunker It would be better to invent a new type of coalbunker without building the CFC to replace coal bunker214 (us the weight borne by the CFC should be trans-ferred to a newly designed bearing system in the WMCB

31 Reinforcement Scheme of the Rock Surrounding the CoalBunker First the rock surrounding the bunker in which avariety of load-bearing structures of the coal bunker arebuilt should be controlled effectively so as to develop aWMCB (erefore FLAC3D models were established toanalyze the stability of the rock surrounding coal bunker 3based on its geological conditions Considering the sym-metrical design of the coal bunker the numerical modelcould be established as shown in Figure 11 the model size is30mtimes 15mtimes 15m Furthermore as can be seen fromFigure 2(b) that the upper boundary of the bunker is thefloor of the belt conveyor roadway the distressed zonewhich was free from the underground pressure was set up atthe top of the bunker in the numerical model (Figure 11)(e rock parameters and constitutive model adopted in thismodel were same as those in the previous FLAC model

(e simulation results (Figure 12) indicate the following(1) the surrounding rock in sandstone segments is basicallystable and the cumulative rock deformation is small (lessthan 25mm) (2) the surrounding rock in coal seam seg-ments which moves into the inside of the bunker with alarge deformation (80ndash110mm) seen is the main area of

CFC

Coarse sandstone

Siltstone

Fine sandstone

Coal seam 4-2

Clay

Mudstone

605 m60

m

Figure 7 Numerical model

σ

ε

Yield

ε = εe ε = εe + εp

Figure 8 Strain-softening constitutive model [33] where εe is theelastic strain and εp is the plastic strain


deformation in the entire surrounding rock mass this isconsistent with the results of field investigation

To ensure the long-term stability of the surrounding rockand supporting structures both the supporting strength andthe supporting bearing systemrsquos stability should be takeninto account (e bolt-cable combined supporting tech-nology [8 35] was adopted to control the deformation of therock surrounding the coal bunker body At the same timesignificant attention should be paid to supporting the rocksurrounding coal seam 4-2 Combined with research resultsof reinforcement mechanism of the bolting with the wiremesh system [36ndash38] specific reinforcement measures inthis work were proposed as follows

(1) (e welded wire mesh a more rigid screen was usedto increase the stiffness of supporting system for thecoal seam segment

(2) (e thickness of the support bearing structure formedby bolting wire mesh and shallow surrounding rockwas increased by increasing the length of the bolt

(3) Apart from the high prestressed bolt and wire meshsystem compensation anchor cables were used to

reinforce the support bearing structure formed bybolting wire mesh and shallow surrounding rockwhich improved the stability of the supportingstructure so as to control the deformation of the rocksurrounding the coal seam segment thus ensuringthe stability of the overall rock mass around thebunker

Based on the measures discussed above six reinforcementschemes were designed and a maximum displacement-monitoring point was set at the center of the coal seam segment(as shown in Figure 12) to evaluate their control effectsAdditionally the main parameters of the bolt and cable whichare both cable elements and available from the userrsquosmanual ofFLAC3D are listed in Table 3 It could be found from Table 4that the maximum displacement of the coal seam segmentdecreases significantly from 89mm to 36mm when the lengthof the bolt increases from 24m to 30m and that of cableincreases from 50m to 62m respectively however the de-formation then decreases to an insignificant extent whenlonger bolts and cables are used Comparison of Schemes 5 and6 shows that the reinforcing interval of the grouted anchorcables have a significant effect on the deformation (erefore

Table 1 Physical and mechanical parameters of surrounding rock and concrete

Strata Density (kgmiddotmminus 3) Bulk modulus (GPa) Shear modulus (GPa) Friction angle (deg) Cohesion (MPa)Coarse-grained sandstone 2600 50 40 28 20Fine-grained sandstone 2500 40 30 26 17Siltstone 2550 35 25 24 15Coal seam 4-2 1400 13 09 18 03Mudstone 1800 20 15 25 07Clay 1500 20 13 23 04Reinforced concrete 2700 50 40 32 22Interface kn ks 125 (GPam)

Table 2 Mechanical parameters of floor strata after immersed in water for 36 h

Strata Elasticity modulus (MPa) Bulk modulus (GPa) Shear modulus (GPa) Friction angle (deg) Cohesion (MPa)Mudstone 1860 120 075 20 036Clay 1650 130 064 18 022

Shear (n)Tension (n)Shear (p)

(a)


(b)

Figure 9 Comparison of plastic zone distribution under conditions (a) without water and (b) with water


the reinforcing interval was selected as 1600times 800mm Finallyan optimized scheme (Scheme 4) was determined (Figure 13)considering the cost installation convenience and technicalfeasibility Figure 13 shows that

(1) (e bolt and wire mesh were used to reinforce theshallow rock and coal mass at intervals of800mmtimes 800mm and the bolt nutrsquos tighteningpretension was not less than 60 kN

(2) (e bearing capacity of the deep surrounding rockwas utilized by installation of the anchor cable(Φ178mmtimes 6200mm) with the spacing and rowspacing being 1600mmtimes 800mm

(3) (e steel ladder bar and set with a diameter ofΦ14mm along the inner surface of the bunker wereused to combine the bolts and anchors thus theoverall stability of the supporting system wasenhanced

2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)

(lowast10lowastlowast1)

(a)

(lowast10

lowastlowast

1)

(lowast10lowastlowast1)2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(b)

Figure 10 Comparison of displacement distribution under conditions (a) without water and (b) with water


(4) Additionally the Φ218mmtimes 10000mm self-lockinganchor cables (Figures 13ndash16) which will be explainedin detail in a later section are also used as com-pensation anchors and were reinforced to improve thestability of the supporting structure formed by thebolting and wire mesh in the coal seam segment(eyalso serve as the auxiliary carrying system able to bearthe full weight of the coal bunker which ensured thelong-term stability of the coal bunker

32 Self-Bearing System of the Coal Bunker

321 Main Bearing System As stated before a new type ofcoal bunker without the CFC was invented to replace thetraditional vertical coal bunker (e rock surrounding thebunker was controlled by a high-strength supportingscheme described in a later section (us the followingsection aims to solve two problems (e first is that a newlydesigned bearing system should be designed to bear the

Distressed zoneSilstone-1Siltstone-2

4-2coal seam

ZoneColorby Group any

BunkerCoarse sandstone

Figure 11 FLAC3D model of coal bunker 3

11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00

Displacementmonitoring point

Contour of displacement

Figure 12 Deformation surrounding the body of coal bunker 3


weight of coal stored in the bunker concrete bearing systemitself and feeder (as shown in Figure 2(b)) the second is thatthe hopper should be formed by a newly designed structurein the bearing system

(e specific design presented as follows as the sandstonerock surrounding the upper part of the bunker is stable theH-steel beams (Figures 2(b) and 14) installed in thesandstone rock uniformly and horizontally bear the wholeweight of coal bunker 3 without considering friction andadhesion between the concrete and the surrounding rock soit was necessary to ensure that the carrying capacity ofH-steel beams (Figures 14 and 15) was greater than the totalweight of the coal bunker with a certain safety factor (usthis computation may be summarized as follows

(e bunker total weight is

MT MC1 + MC2 + MB + MF (2)

whereMC1MC2MB andMF are the weight of coal when thecoal bunker is filled the weight of concrete the total weight ofthe H-steel brackets and the weight of the feeder (Figure 2(b))respectively (e weight borne by each H-steel beam is

M MT

n (3)

where n is the number of H-steel beams buried in the bunkerwall rock (en the shear stress on the section of the H-steelbeam is

τ Mg

S (4)

where S is the cross-sectional area of the H-steel beam(us the designed safety factor can be given by

K1 [τ]

τ (5)

where [τ] is the allowable shear stress in the H-steel beamAs discussed above the lower part of the surrounding

rock is coal seam 4-2 with low strength which is unstableand could not be used to bear the weight of the hopperlocated in the bunker bottom (Figures 14 and 15) (en toform the skeleton of the hopper and enhance the overallstability of the structure of the bunker the H-steel bracketswere designed and installed uniformly along the internalsurface rock mass in the bunker (Figures 14 and 15) (eupper ends of the H-steel brackets were embedded into thestable surrounding rock in the upper portion of the coalbunker the bottom parts of brackets were fitted together to

form the skeleton of the hopper Additionally the upperportions of H-steel brackets were fixed to the rock by theanchor cable thus not only transferring the bearing capacityof the deep rock and improving the stability of the shallowsurrounding rock but also enhancing the stability of theframe formed by these H-steel brackets

322 Assisted Bearing System As the lower part of thebunker is the weak coal seam there was a weak interfacebetween the rock and coal seam (Figure 14) Furthermore thebunker bottom was equipped with a hopper and a coal feederand the stability of the lower part of the bunker requires specialattention(en the assisted bearing system which included 16self-locking anchor cables (Figure 16) arranged uniformly inthe bunker funnel section along the bunker wall rock was alsodesigned to enhance the long-term stability of the wholebunker (us the weight of the bunker hopper was borne bythe sandstone and deep stable coal with the self-locking anchorcable anchored therein (the length of the anchor cables were10000mm ensuring that its anchoring ends were in the stablesandstone rocks) thereby ensuring the long-term stability ofthe coal bunker which is beneficial to the stability of beltroadway under the coal bunker Figure 16 shows the samplestructure of the self-locking anchor cable (e vertical com-ponent force of the self-locking anchor cable is

Fv nF sin α (6)

where n is the number of self-locking anchor cables Fv is thevertical component force provided by the self-locking an-chor cable F is the single anchor bearing capacity and α isthe angle between the cable and the rock face and given thatthe whole weight of the bunker is borne by the self-lockinganchor cables the designed safety factor can be given by

K2 Fv

MTg (7)

323 Safety Assessment (e bunker body and hopperheights are 11235mm and 3765mm respectivelyAccording to the Mining Engineering Design Manual [39]the total thickness of concrete around the coal bunker is notless than 400mm and the concrete strength is 40MPa

(e total weight (concrete coal and coal-feeder beam) iscalculated as follows

V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)

Table 3 Parameters of the supporting elements used in the nu-merical model

Property Bolt CableDimensions (mm) Oslash20times L1 Oslash178times L2Elastic modulus (GPa) 25 200Yield strength (kN) 150 450Stiffness of the grout (Nm2) 2times107 2times108

Cohesive capacity of the grout (Nm) 10times105 10times105

Grouted length (mm) 05 L1 05 L2Pretension force (kN) 60 120


where V1 Q V2 Mc1 Mc2 and MB are the coal bunkerrsquosfunnel volume bunker volume concrete volume coal weightconcrete weight and total weight of the H-steel bracketsrespectively H is the bunker design height 15m H1 is thecoal funnel height 3765m H2 is the bunker body height11235m D is the section diameter of the bunker 58mD1 isthe net cross-sectional diameter of the bunker 5m b1 is themouth width of the funnel 123m the weight of coal feeder is45times103 kg Pl is the lineal density of the H-steel 2605 kgmLB is the H-steel bracket length 15013m nB is the number of

H-steel barn brackets 12 and ρc1 and ρc2 are the density of thecoal (14times103 kgm3) and concrete (2714times103 kgm3) re-spectively (ese data are substituted into equation (2) thusthe value of MT can be calculated to be 7771times 103 kg Withthe number of H-steel beams being 60 its cross-sectional areabeing 0003318m2 and its allowable shear stress being125MPa the safety factor can be calculated as

K1 1253825

326gt 3 (9)

Table 4 Six different reinforcement schemes and their control effect (unit mm)

Scheme (no) Bolt (diametertimes length) Anchor cable (diametertimes length) Cable interval (spacingtimes rowspacing)

Maximum displacement incoal seam segment

1 Φ20times 2400 Φ178times 5000 800times 800 732 Φ20times 2400 Φ178times 5000 1600times 800 893 Φ20times 3000 Φ178times 6200 800times 800 364 Φ20times 3000 Φ178times 6200 1600times 800 475 Φ20times 3600 Φ178times 7300 1600times 800 326 Φ20times 3600 Φ178times 7300 1600times1600 61

1500

0

1600

2400

2400

17610

1600

Bolt Φ22 times 3000mm

11 H-steel beam 1200mm

Anchor cable Φ178 times 6200mm

Steel ladder beam Φ14mm

800

H-steel bracketSelf-locking anchor cableΦ218 times 10000mm

800

Figure 13 Expanded view of the supporting scheme for the coal bunker


Unlike surface buildings for an underground rock en-gineering project the long-term property of rocks in un-derground environment and the carry capacity loss of thesupporting element should be considered However therelated estimates are complex and difficult to quantifyAccording to the Mining Engineering Design Manual [39]the stability coefficient is designed to be 25 considering thefactors such as variable loads combined loads (includingtension bending and torsion) ground pressure and ca-pacity loss of the bearing components however the long-term rock property of sandstone which is the key bearingstrata should also be considered so the long-term strengthcoefficient is set as 085 (us the rated safety factor in thisbunker is assigned to be approximately 3 (e calculatedfactor could meet safety requirements well More impor-tantly the actual security needs to be verified by the fol-lowing field engineering application

(e diameter of the self-locking anchor cable is 218mmand its carrying capacity is 458 kN Substituting these datainto equations (6) and (7) the designed safety factor can becalculated as follows

K2 103617927771 times 98

136gt 1 (10)

Here because the assisted system serves to guarantee thelong-term stability of the bunker assume that all the weightof the bunker was carried by the assisted bearing system therated safety factor K2 is assigned to be 1 Furthermorecertain safety reserves should be considered in undergroundbuildings so this meets safety requirements

4 WMCB Application

In practice the new bunker was built according to thefollowing technical procedures (Figure 17) First theroadway below the WMCB should be reinforced before theexcavation of the WMCB by the anchor cables(Φ178mm times 6200mm) with the spacing and row spacingbeing 1600mm times 800mm which was determined accord-ing to the specific reinforcement measures mentionedpreviously and acted as a compensating support Secondexcavate the circular coal bunker by means of stepwisedeletion of the rocks a total of 19 cycles with the excavatingface advancing by 08m from top to the bottom in everycycle during which the bolt-mesh-cable system was in-stalled immediately based on the supporting scheme(Figure 13) (ird install or fix the self-designed H-steel

5800

Hot rolling H-steel 40bH-steel 11

Interface betweenthe rock and coal seam

Self-locking anchor cable(Φ218 times 10000 mm)

Hopper

Anchor cable forfastening the H-steel bracket(Φ218 times 6200 mm)H-steel bracket

H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete

Figure 14 Schematic diagram of the WMCB


beams H-steel brackets and the self-locking anchor cablesbased on the design scheme as shown in Figures 13 and 14Fourth configure rebars and carry out formwork aroundthe bunker Fifth pour concrete into the space between thetemplates and the sidewall thus immersing all the bearingelements in the concrete and forming the WMCB(Figures 2(b) and 15) Finally complete the installation ofrelated components at the top of the bunker as shown inFigure 14

(e wall-mounted bunker had been in operation for fiveyears (2013ndash2018) Long-term monitoring data (Figure 18)and site observation show that the cumulative slippage of thewhole bunker body was 646mm the coal bunker diameterconvergence measured by crossing method was 520mmand no cracking occurred at the reinforced concrete sincethe application of the WMCB

(e great economic benefits due to the application of theWMCB are shown in Table 5 As coal bunker 214 couldremain stable less than three months after repair it should berepaired for a month every time (e annual productioncapacity of the mine is 24 million tons and the use of theWMCB gives rise to a production increase of more than twohundred thousand tons of coal every year (an economicbenefit of 2322 million USD at a unit-price of 3869 USD perton) Furthermore the application of the WMCB reducescosts for the construction and maintenance of the originalCFC even though the construction cost of the WMCB is0582 million USD and the construction time is two months(production delay with a financial loss of 1548 millionUSD) the coal mine has gained an economic benefitamounting to 101906 million USD over five years

5 Discussion

In this study the influencing factors and failure mode of theCFC were revealed (en the WMCB was designed to avoidthe influence of floor heave during which a self-bearingsystem which included H-steel beams H-steel brackets andself-locking anchor cables formed a replacement for theCFC to bear the whole weight of the bunker thus the wholeweight was transferred to the stable and deep rocks (estability of the new type of the coal bunker was verified inXiashijie coal mine and made coal production therein moreefficient

Comparison of the WMCB and the traditional verticalcoal bunker shows the differences between them in that theformer is a new vertical coal bunker without the CFC and canremain stable when the floor heave is severe or the strength ofthe floor rock is especially low thus the new coal bunker is abetter solution to the floor heave issue To date no verticalcoal bunkers without CFC have been reported (e new coal

Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable

Anchor cable used tofasten the H-steel brackets

Figure 15 3D view of the bearing structure of the WMCB

45deg cast-iron wedge

Channel 18 steel plate

45deg

Lockset

Anchor cable

Figure 16 Structure diagram of the self-locking anchor cable


bunker is stable and easy to maintain and it offers greatpotential for application in mines with similar geologicalconditions In addition the newly designed coal bunker wasgranted a patent for invention in 2015 by State IntellectualProperty Office of the Peoplersquos Republic of China [40]

(e work in this paper is preliminary and the techniquesused herein for stabilizing the coal bunker are mainly fo-cused on field engineering Further theoretical researchshould be performed in the future

6 Conclusions

(1) (e failure mechanism of the CFC was that the floorrocks were liable to swelling due to mine water (estrength of the floor rock decreased and theswelling rock mass generated significant expansive

forces A much larger ranging plastic zone anddeformation appeared in rocks surrounding thefloor causing tensile failure that occurred first inthe floor concrete further resulting in shearingdamage in the sidewalls and tension and shearingcollapse in the reinforced column and eventuallyoverall instability of the CFC occurred

(2) (e WMCB was designed to replace the traditionalvertical coal bunker and the stability of its sur-rounding rock was simulated and analyzed (eresults showed that the surrounding rock in the coalseam segment was the main deformation area (enthe surrounding rock was controlled by an optimizedhigh-strength bolt-cable support scheme Moreimportantly a self-bearing system of the wall-mounted bunker was invented that was composed of

(a) (b) (c)

(d) (e) (f )

(g) (h)

Figure 17 Construction procedures (a) Installation of the bolt-mesh-cable system and the self-designed H-steel beams during stepwiseexcavation of the rocks (b) installation of the self-designed H-steel brackets (c) installation of the self-locking anchor cables (d) fitting thebottom parts of H-steel brackets together to form the skeleton of the coal hopper (e) configuring rebars around the bunker (f ) pouringconcrete and (g) that was vibrated to remove any entrapped air bubbles and (h) installation of related components at the top of the bunker


H-steel beams H-steel brackets with fastened an-chors and self-locking anchor cables and was able tobear the whole weight of the coal bunker thus ne-gating the need for a bearing structure at the bottom

(3) (e WMCB differs from the traditional coal bunkerin that the former without the CFC is easier tomaintain than the latter and it could be remainstable in spite of severe floor heave

(4) (e new coal bunker has been put into practice atXiashijie coal mine and its specific constructiontechnology is presented in detail Field testing provesthat the WMCB being stable and safe contributes toa significant enhancement in production (e coalmine has accrued economic benefits amounting to101906 million USD over three years (2013ndash2018)

(5) It is key to construct a WMCB rather than a tra-ditional coal bunker under geological conditionsencompassing severe floor heave loose (or fractured)and weak rock masses and other similar conditions(e WMCB offers great prospects for application inother mines subject to similar geological conditions

Data Availability

(e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

(e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

We wish to thank Xiashijie coal mine for supporting thisimportant study as well as Xiaoquan Huo and Ming Xu forassistance with field construction and data collection Wewould like to thank Editage (httpwwweditagecn) forEnglish language editing (is work was funded by the StateKey Laboratory of Coal Resources and Safe Mining theChina University of Mining and Technology (Grant NoSKLCRSM15X01) and the National Key Research andDevelopment Plan (Grant No 2017YFC0603001)

References

[1] L M Alotin and V L Belgorodskii ldquoPractice and theory ofimproving coal output by the use of a storage bunker in thetransportation linerdquo Soviet Mineral Science vol 6 no 6pp 700ndash702 1971

[2] F Liu ldquoResearch on failure mechanism and its controltechnology of shaft coal pocketrdquo Masterrsquos thesis ChongqingUniversity Chongqing China 2008 in Chinese with Englishabstract

[3] B Sureshc D Carlos and H Michael ldquoOptimum bunker sizeand location in underground coal mine conveyor systemsrdquoInternational Journal of Mining and Geo-Engineering vol 5no 4 pp 391ndash404 1987

[4] L Wang ldquoAnalysis and calculation of capacity of un-derground coal bunkerrdquo Journal of Huainan Mining vol 1pp 113ndash122 1983

[5] V M Shramko ldquoInfluence of the collection bunker capacityto the utilization level of the main mine subsystemsrdquo SovietMining Science vol 20 no 6 pp 489ndash492 1984

0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)

Cumulative slippageDiameter convergence

27-Dec-1414-Aug-13 4-Feb-1922-Sep-17Date

Figure 18 Monitoring of bunker fall and diameter convergence

Table 5 Calculation of the economic benefits (unit million UD)

Cost of coal bunker 214 Cost of the WMCB

Constructioncost

Constructiontime

Cost of repair of coal bunker 214 every yearConstruction

costConstruction

timeDelayed production

efficiencyRepaircost

Failuretime

Delayed productionefficiency

A 0398 Two months B 0294 (reemonths C 2322 D 0582 Two months E 1548

Net benefit over five years A+ (B+C)times 5 minus D minus E 101906


[6] F Duckmanton and R Carlin ldquoVertical bunkerrdquo CollieryGuardian Redhill vol 234 pp 444ndash446 1986

[7] S B Tang and C A Tang ldquoNumerical studies on tunnelfloor heave in swelling ground under humid conditionsrdquoInternational Journal of Rock Mechanics and Mining Sci-ences vol 55 pp 139ndash150 2012

[8] Y Kang Q Liu G Gong and H Wang ldquoApplication of acombined support system to the weak floor reinforcement indeep underground coal minerdquo International Journal of RockMechanics and Mining Sciences vol 71 pp 143ndash150 2014

[9] W X Zheng Q W Bu and Y Q Hu ldquoPlastic failure analysisof roadway floor surrounding rocks based on unified strengththeoryrdquo Advances in Civil Engineering vol 2018 Article ID9483538 10 pages 2018

[10] W Q Peng W J Wang and C Yuan ldquoSupporting tech-nology research in deep well based on modified terzaghiformulardquo Advances in Civil Engineering vol 2018 Article ID7475698 6 pages 2018

[11] Q A Cui and J J Shen ldquoLocation Selection of Coal BunkerBased on Particle Swarm Optimizationrdquo in Proceedings of the19th International Conference on Industrial Engineeringpp 1121ndash1128 Berlin Heidelberg Germany June 2013

[12] W F Ma J S Chen and J C Zhao ldquoLarge-scale coal bunkerengineering practice in deep shaftrdquo Shanxi Architecturevol 38 pp 117-118 2012

[13] H T Ma ldquoDesign and construction technology of coal bunkerwith large diameter and high vertical heightrdquo Coal Engi-neering vol 47 pp 42ndash44 2015

[14] Z Q Li I A Oyediran C Tang R L Hu and Y X ZhouldquoFEM application to loess slope excavation and support casestudy of Dong Loutian coal bunker Shuozhou ChinardquoBulletin of Engineering Geology and the Environment vol 73no 4 pp 1013ndash1023 2014

[15] H Wang ldquoStudy on water inrush prevention technology oftemporary coal bunker constructionrdquo Coal Engineeringvol 16 pp 46ndash48 2013

[16] H-l Lv Y Ma S-C Zhou and K Liu ldquoCase study on thedeterioration and collapse mechanism and curing techniqueof RC coal bunkersrdquo Procedia Earth and Planetary Sciencevol 1 no 1 pp 606ndash611 2009

[17] R Q Dong ldquoAnti failure technology of 100 m high verticalcoal silordquo Coal Science and Technology vol 37 pp 18ndash212009

[18] Q Gong ldquoA study on coal bunker dredging technology underhighly dynamic pressure and a portable dredgerrdquo China Coalvol 34 pp 67ndash69 2008

[19] Q Gong ldquoAnalysis on blockage of coal bunker and its pre-ventionrdquo Mining and Processing Equipment vol 36 pp 24ndash26 2008

[20] J P Sun and J Jiang ldquoLaser monitoring of the coal level ofcoal silo by depth pre-calibrationrdquo Journal of China CoalSociety vol 37 no 1 pp 172ndash176 2012

[21] Z-A Song F Zhan C-Y Li Z-L Wang and S-L ZhangldquoResearch of the underground coal bunker clearing robotrdquoJournal of Coal Science and Engineering (China) vol 16 no 1pp 104ndash107 2010

[22] X L Zhao J W Shen and W W Shang ldquoPractice andresearch on natural ventilation of cylindrical coal bunker forgas exhaustrdquo Coal Engineering vol 46 pp 137ndash139 2014

[23] F T Wang C Zhang S F Wei X G Zhang and S H GuoldquoWhole section anchor-grouting reinforcement technologyand its application in underground roadways with loose andfractured surrounding rockrdquo Tunnelling and UndergroundSpace Technology vol 51 pp 133ndash143 2016

[24] GBT 2356114-2010 Methods for Determining the Physicaland Mechanical Properties of Coal and RockmdashPart 14Methods for Determining the Swelling Ratio of Rock StateStandard of the Peoplersquos Republic of China Beijing China2010

[25] X H Wang X J Du G R Feng and L X Kang ldquo(eoccurrence mechanism of rock burst in the three hard coalseam roadwayrdquo Journal of Mining and Safety Engineeringvol 34 pp 663ndash669 2017

[26] S Liang D Elsworth X H Li X H Fu B Y Sun andQ L Yao ldquoKey strata characteristics controlling the integrityof deep wells in longwall mining areasrdquo International Journalof Coal Geology vol 172 pp 31ndash42 2017

[27] M I Alvarez-Fernandez C Gonzalez-Nicieza A E Alvarez-Vigil G Herrera Garcıa and S Torno ldquoNumerical modellingand analysis of the influence of local variation in the thicknessof a coal seam on surrounding stresses application to apractical caserdquo International Journal of Coal Geology vol 79no 4 pp 157ndash166 2009

[28] X J Du G R Feng T Y Qi et al ldquoRoof stability analyses ofwater-preserved and water-stored coal mining with con-struction backfill miningrdquo Journal of China Coal Societyvol 44 pp 820ndash829 2019

[29] T Gentzis N Deisman and R J Chalaturnyk ldquoA method topredict geomechanical properties and model well stability inhorizontal boreholesrdquo International Journal of Coal Geologyvol 78 no 2 pp 149ndash160 2009

[30] D Ma X Miao H Bai et al ldquoEffect of mining on shearsidewall groundwater inrush hazard caused by seepage in-stability of the penetrated karst collapse pillarrdquo NaturalHazards vol 82 no 1 pp 73ndash93 2016

[31] E Hoek and E Brown ldquoPractical estimates of rock massstrengthrdquo International Journal of Rock Mechanics andMining Science amp Geomechanics Abstracts vol 34 no 8pp 1165ndash1186 1997

[32] P Marinos and E Hoek ldquoGSI a geologically friendly tool forrockmass strength estimationrdquo in Proceeding for the Geo Eng2000 at the International Conference on Geotechnical andGeological Engineering pp 1422ndash1446 Technomic PublishersMelbourne Australia November 2000

[33] Itasca Consulting Group Inc Manual of FLAC Version 5Itasca Consulting Group Inc Minneapolis MN USA 2005

[34] C Wu J Luo R J Tian G Liu H K Li and X L Zhangldquo(e effect of Mud-shale hydration on rock mechanic pa-rametersrdquo Journal of Oil Gas Technology vol 34 no 4pp 147ndash150 2012

[35] Q Meng L Han J Sun F Min W Feng and X ZhouldquoExperimental study on the bolt-cable combined supportingtechnology for the extraction roadways in weakly cementedstratardquo International Journal of Mining Science and Tech-nology vol 25 no 1 pp 113ndash119 2015

[36] B Shen ldquoCoal mine roadway stability in soft rock a casestudyrdquo Rock Mechanics and Rock Engineering vol 47 no 6pp 2225ndash2238 2014

[37] H Basarir Y Sun and G Li ldquoGateway stability analysis byglobal-local modeling approachrdquo International Journal ofRockMechanics andMining Sciences vol 113 pp 31ndash40 2019

[38] X K Wang W B Xie S G Jing Z L Su L H Li andL H Lu ldquoExperimental study on large deformation controlmechanism of surrounding rock of extremely loose coalroadway in gliding tectonics areardquo Chinese Journal of RockMechanics and Engineering vol 37 pp 312ndash324 2018


[39] R L Zhang G W He and D Li Mining Engineering DesignManual pp 1550ndash1605 Coal Industry Press Beijing China2003

[40] China University of Mining and Technology A Wall-Mounted Vertical Bunker Without A Coal Feeder ChamberState Intellectual Property Office of the Peoplersquos Republic ofChina Beijing China Grant No CN2013104653017 2014


International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

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Hindawiwwwhindawicom Volume 2018


Active and Passive Electronic Components

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

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Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of



Journal ofEngineeringVolume 2018

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RotatingMachinery


Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018


Chemical EngineeringInternational Journal of Antennas and

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Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

load-bearing structure of the CFC Figure 3 shows the largedeformation that occurred in the CFC

On the one hand much research has been devoted tostudy floor heave of chamber in coal mines [7ndash10] Nev-ertheless floor-heave control is a complex problem in un-derground coal mines the solution approaches arecommonly a combination of bolts anchor cables concreteand steel inverted arches and such construction techniquesare not only difficult to carry out in the field but the ap-plication effect is also poor On the other hand the study ofthe existing literature for coal bunker mainly focuses on (i)the optimum bunker size and location selection in un-derground coal mine conveyor systems [3 11] (ii) theconstruction of the coal bunker with a large diameter andvertical height [12 13] (iii) the optimization of methods of

safe construction under different geological conditions[14 15] (iv) the deterioration and collapse mechanism of thereinforced concrete bunker [16] (v) the curing technique ofblockage and fractures in the walls of the coal bunker body[17ndash19] and (vi) the maintenance of the coal bunker [20ndash22] (ose studies have made significant progress Howeverthere are no generally accepted cases applicable to con-struction of a new type of vertical coal bunker (Figure 2(b))without a CFC especially when the CFC of the traditionalcoal bunker could not be stable within weak floor rock

(is work used field surveys theoretical analysis labo-ratory tests and numerical simulation to analyze the mainfactors causing floor heave and the failure mechanism of theCFC (en a new coal bunker called a wall-mounted coalbunker (WMCB) without a CFC was invented and

Main haulage roadway

Coal bunker inmining area

Coal bunkernear sha

Mainsha

Longwallpanel no1Belt

hauling en

try

Figure 1 Coal transportation system in an underground coal mine

Belt haulageroadway

Coal bunkerbody

Coal-feeder chamber

Conveyors

Reinforced column

Foundations

Concrete

(a)

Conveyors

Roadways

Sandstone

Conveyors

Coal seam

Feeder

Concrete

(b)

Figure 2 Structure of (a) traditional vertical bunker 214 and (b) the new designed vertical bunker without CFC



2 Background









Roof was cracked

(a)

Roof was fractured

(b)

Roof


(c)


(d)







214 coal bunkerAir





953 Sump


0

300

600

900

1200

1500

1800

0 20 40 60 80 100

Conv

erge

nce (

mm

)




0

2

4

6

8

10

12

0 5 10 15 20 25 30

Dila

tatio

nal s

trai

n (times

10ndash3

)

Monitoring time (h)




kn ks 10K +(43)G

Δzmin1113890 1113891 (1)










CFC

Coarse sandstone

Siltstone

Fine sandstone

Coal seam 4-2

Clay

Mudstone

605 m60

m


σ

ε

Yield
















(a)


(b)







2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)


(a)

(lowast10

lowastlowast

1)


3600

3400

3200

3000

2800

2600

(b)







4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



2 Background









Roof was cracked

(a)

Roof was fractured

(b)

Roof


(c)


(d)







214 coal bunkerAir





953 Sump


0

300

600

900

1200

1500

1800

0 20 40 60 80 100

Conv

erge

nce (

mm

)




0

2

4

6

8

10

12

0 5 10 15 20 25 30

Dila

tatio

nal s

trai

n (times

10ndash3

)

Monitoring time (h)




kn ks 10K +(43)G

Δzmin1113890 1113891 (1)










CFC

Coarse sandstone

Siltstone

Fine sandstone

Coal seam 4-2

Clay

Mudstone

605 m60

m


σ

ε

Yield
















(a)


(b)







2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)


(a)

(lowast10

lowastlowast

1)


3600

3400

3200

3000

2800

2600

(b)







4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia






214 coal bunkerAir





953 Sump


0

300

600

900

1200

1500

1800

0 20 40 60 80 100

Conv

erge

nce (

mm

)




0

2

4

6

8

10

12

0 5 10 15 20 25 30

Dila

tatio

nal s

trai

n (times

10ndash3

)

Monitoring time (h)




kn ks 10K +(43)G

Δzmin1113890 1113891 (1)










CFC

Coarse sandstone

Siltstone

Fine sandstone

Coal seam 4-2

Clay

Mudstone

605 m60

m


σ

ε

Yield
















(a)


(b)







2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)


(a)

(lowast10

lowastlowast

1)


3600

3400

3200

3000

2800

2600

(b)







4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



kn ks 10K +(43)G

Δzmin1113890 1113891 (1)










CFC

Coarse sandstone

Siltstone

Fine sandstone

Coal seam 4-2

Clay

Mudstone

605 m60

m


σ

ε

Yield
















(a)


(b)







2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)


(a)

(lowast10

lowastlowast

1)


3600

3400

3200

3000

2800

2600

(b)







4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia














(a)


(b)







2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)


(a)

(lowast10

lowastlowast

1)


3600

3400

3200

3000

2800

2600

(b)







4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia






2500 2700 2900 3100 3300 3500

3600

3400

3200

3000

2800

2600

(lowast10

lowastlowast

1)


(a)

(lowast10

lowastlowast

1)


3600

3400

3200

3000

2800

2600

(b)







4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia






4-2coal seam




11037E ndash 01

11000E ndash 01

10000E ndash 01

90000E ndash 02

80000E ndash 02

70000E ndash 02

60000E ndash 02

50000E ndash 02

40000E ndash 02

30000E ndash 02

20000E ndash 02

10000E ndash 02

00000E + 00








MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia





MT MC1 + MC2 + MB + MF (2)


M MT

n (3)


τ Mg

S (4)


K1 [τ]

τ (5)





Fv nF sin α (6)


K2 Fv

MTg (7)



V1 13πH1

D1 + b1

21113888 1113889

2

minusD1b1

4⎡⎣ ⎤⎦

Q V1 +14πD

21H2

V2 14πD

2H minus Q

MC1 ρc1Q

MC2 ρc2V2

MB PlnBLB

(8)








K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




K1 1253825

326gt 3 (9)





1500

0

1600

2400

2400

17610

1600





800


800





K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




K2 103617927771 times 98

136gt 1 (10)


4 WMCB Application


5800




Hopper


H-steel beam

400

5000

1000

800

1000

180011

235

3765

800

1200

1200

1200

1230

500

45deg45deg

60degCenter line

Concrete






5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia





5 Discussion



Self-locking cable

H-steel bracket

Bolt

H-steel beam

Anchor cable





45deg

Lockset

Anchor cable





6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




6 Conclusions




(a) (b) (c)

(d) (e) (f )

(g) (h)







Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia






Data Availability




Acknowledgments


References






0

10

20

30

40

50

60

70

10-May-16

Conv

erge

nce (

mm

)






Constructioncost

Constructiontime


costConstruction



Failuretime












































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia









































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


Large-DeformationFailureMechanismofCoal-FeederChamber...

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