Ground Improvement Rao Dutta

8/10/2019 Ground Improvement Rao Dutta

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GROUND IMPROVEMENT WITH WASTE PLASTIC

G Venkatappa Rao, Indian Institute of Technology, New Delhi, IndiaR.K.Dutta, National Institute of Technology, Hamirpur, India

ABSTRACTThe results of conventional drained triaxial compression tests conducted on 100 mm diameter

x 200 mm high specimens of sand with two types of waste plastics are presented in this paper. Thisexperimental data is utilised to assess the overall influence of such reinforced material on the bearingcapacity improvement of granular trench. It has been concluded that inclusion of waste plastic strips in

sand improves the bearing capacity of granular trench.

Keywords: Triaxial test !aste plastic "and #ranular trench $earing capacity.

1. INTRODUCTION

The amount of wastes has increased year by year and the disposal becomes a serious problem.%articularly recycling ratio of the plastic wastes in life and industry is low and many of them have beenreclaimed for the reason of unsuitable ones for incineration. It is necessary to utilise the wasteseffectively with technical development in each field.

The estimated municipal solid waste production in India upto the year 2000 was of the order of &'million tons per year. This figure is most li(ely to touch )* million tons per year by the year 2010 +,-.

The typical percentage of plastic in the municipal solid waste produced in India is 1 . The best way tohandle waste plastic is to utili/e it for engineering application after shredding in order to conserve thescarce natural valuable resource li(e sand.

The paper presents the test results of conventional consolidated drained triaxial on sand reinforcedwith two types of plastic wastes. The results have been further utilised to assess the influence of suchreinforced material on the bearing capacity improvement of granular trench.

. LITERATURE REVIEW

any investigators have conducted the studies on fiberreinforced materials. The results of directshear tests performed on sand specimens +- indicated increased shear strength increased ductilityand reduced post pea( strength loss due to the inclusion of discrete fibers. These results weresupported by a number of researchers. Investigations were also conducted to determine the behaviourof material properties of fiberreinforced sands. The failure envelopes for fibersand composites werebilinear +-. The critical confining stress was a function of surface friction properties of the fibers and


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soil. The inclusion of discrete fibers increased both the cohesion and angle of internal friction of thespecimens +3-. The improvement of the engineering properties due to the inclusion of discrete fiberswas determined to be a function of a variety of parameters including fiber type fiber length aspectratios fiber content orientation and soil properties. The pea( strength reportedly increased withincreasing fiber content and length up to a limiting amount of each beyond which no additional benefitswere observed +)- +*- +- and +3-.

4ut pieces of 56%7 waste mil( 8ugs +1- when mixed with sand have shown that there is anincrease in strength 4$9 and secant modulus of sand and friction angle increase was as large as 13degrees. The laboratory study on soils which are mechanically stabili/ed with short thin plastic strips ofdifferent lengths and contents +&- have shown an enhancement of strength and load bearing capacity.

Thus it is evident that not much wor( has been reported on the sand reinforced with waste plasticfor its application to granular trench problems.

!. E"PERIMENTAL PROGRAMME

!.1 Pa#a$ete#% Va#&e'

To investigate the effects of test parameters on the mechanical behaviour of unreinforced sand andreinforced sand a total of )* triaxial compression tests were performed. The test parameters included:

four confining pressures &,.) (%a to 2* (%a; 2 types waste plastic strips with percentage varyingfrom 0.0) to 0.1) for Type I and 0.2) to 2 for Type II 2 types of strips and two differentlengths of strip.

!. Te%t Mate#&a(%

!..1 San'

The investigation was carried out on locally available $adarpur sand which is medium grained uniform


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!.+ Re%u(t%

The summary of the typical triaxial test results on sand with strip Type I and Type II are presented inTables 1 to ).

Table 1 Balues of ma8or principal stress at failure

Type ofinclusion

strip

1;f at different confining pressures (%a;

A $

&,.) *' 1&3 2* &,.) *' 1&3 2*

0 1&).01 &2'.* ),3.*, 111.0& 1&).01 &2'.* ),3.*, 111.0&

Type I 0.0) 201.)2 &3.)1 )''.'2 12').3' 13,.2 &3.&3 )'&.01 123).',

0.10 20).&' ,03.0, *11.' 1&1&.*& 13.2& ,0,.,' *02.31 1&00.0'

0.1) 210.,* ,2.&) *2*.2 1&&*.2 1'1.1) ,13.& *21.*3 1&1&.&)

Type II 0.2) 1**.&& &3'.&' *1,.2) 12',.,' 1)*.22 &,.'3 )').)) 12'1.**

0.)0 11.&) ,0'.&2 *,0.*& 1&0'.*3 1)'.') &3*.1) *0'., 12''.&3

1 1.,) ,&&. *30., 1&1.2) 1*,. ,02.01 *23.'3 1&2,.)2

2 131.32 ,,&.03 00.& 1,)).*' 10.33 ,1*.'* *,.2) 1&.**

Table 2 "trength parameters for sand with strip Type I A

9ange of

&(%a;

"trengthparameter

%ercentage inclusion

0 0.0) 0.10 0.1)

C*' c(%a; 0 0 0 0

deg.; &3 ,,.2 ,).& ,*.2

*' to 2* c(%a; 0 . 11.) 1,.3

deg.; &3 &'.* &'.* &'.3

Table & "trength parameters for sand with strip Type I $

9ange of

&(%a;

"trengthparameter


0 0.0) 0.10 0.1)

C*' c(%a; 0 0 0 0

deg.; &3 ,&. ,).1 ,).3

*' to 2* c(%a; 0 *.0 11.2 1).&

deg.; &3 &'.* &'., &'.&

Table , "trength parameters for sand with strip Type II A

9ange of

&(%a;"trength

parameter%ercentage inclusion

0 0.2) 0.)0 1 2

C*' c(%a; 0 0 0 0 0

deg.; &3 ,,., ,).) ,*. ,.1

*'to 2*

c(%a; 0 10.) 1*.3 1'.3 1&.)

deg.; &3 &'., &'.2 ,0.1 ,1.3

Table ) "trength parameters for sand with strip Type II $

9ange of

&(%a;

"trengthparameter


0 0.2) 0.)0 1 2

C*' c(%a; 0 0 0 0 0

deg.; &3 ,&. ,,.& ,).2 ,).'

*' to 2* c(%a; 0 ,.' 3., 11., 10.,


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deg.; &3 &'.3 &'.* &'.' ,0.3

!. APPLICATION TO GRANULAR TRENCH

An analysis has been carried out to understand the changes brought out in ultimate bearing capacityof a footing on granular trench ?ig. 1; when the waste plastic strips are introduced into the trenchmaterials following the procedure +'- developed.

?ig. 1 #ranular trench with and without waste plastic strips

?or this the wea( clay deposit has been assumed to possess cohesion 42; of 20 (%a. The valuesof 49of reinforced material for granular trench 4 1is replaced by 49of reinforced material; adoptedherein are based on pseudocohesion concept suggested +10-. In this study the values of 49 havebeen extracted from the results of triaxial tests conducted on the corresponding material. The footingis placed at a depth 6f; of 1.0 m below ground level and rests directly on granular trench. Thegranular trench width A; is so varied as to obtain A>$ ratios from 0., to 2.0 in steps of 0.,. The unitweight of clay is 1).0 (=>m&. The typical variations of $49 ratio of ultimate bearing capacity of clay with sand in the granulartrench to the ultimate bearing capacity of clay with sand reinforced with waste plastic strips in thegranular trench; with A>$ ratio for $D 1.0 m are illustrated in ?igs. 2 E & for sand with strip Type I andType II respectively. A study of these figures reveal the following.

1. The values of $49 increase with increase in A>$ in a bilinear manner.2. The values of $49 increase with increase in strip percentage.&. The values of $49 also increase with the increase in the length of reinforcing strips i.e. they are

higher for Type I A and II A strips than Type I $ and II $ strips. This is as expected.


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,. In ?igure & at 0.)0 of Type II A and 2 of Type II $ the $49 values are comparable.

?ig. 2 Bariation of $49 with A>$ ratio for sand with strip Type I.

?ig. & Bariation of $49 with A>$ ratio for sand with strip Type II.

+.1 Co$pa#&%on

The $49 values computed for sand in the granular trench reinforced with strip Type I and Type II inthe present study are compared and the results are shown in ?ig. ,. A study of ?ig. , indicate that:

1. !ith 2 Type II A inclusions the $49 values are the maximum followed by 1 Type II A strip.5owever the $49 values are comparable when 2 Type II $ 0.) Type II A and 0.1) Type IA strips were added to the sand.

2. ?rom ?ig. , it can also be seen that with 0.1) Type I $ strip the $49 values are more thanthose of 1.0 of Type II $ strip when added to the sand. "imilarly for 0.10 Type I A and 0.10 Type I $ the $49 values are more than those of 0.2) Type II A and 0.)0 Type II $ strips

when added to sand.&. ?urther when 0.0) Type I A and 0.0) Type I $ strips are added to the sand the $49 valuesare more than when 0.2) of Type II $ strips are added to the sand.


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?ig. , 4omparison of $49 with A>$ ratio for sand with strip Type I and Type II.

+. E,,e)t o, -oot&n W&'t/

5erein an analysis has been carried out to understand the effect of footing width on the $49 values.?or this the values of footing width $; were ta(en as 1.0 m 1.) m and 2.0 m. The typical variation of$49 with footing width for different A>$ ratios for sand in the granular trench reinforced with 0.1)Type I A and 2 Type II A strips are presented in ?ig. ). A study of ?ig. ) reveals that there ismarginal decrease in the $49 with the increase in footing width. This trend is observed at all A>$ratios. "imilar study is conducted for the other cases also.

?ig. ) Bariation of $49 with footing width for different A>$ ratios.

+.! Co$pa#&%on 0&t/ Geo#&' M&)#o Me%/ Re&n,o#)e' San'

The $49 values computed for sand reinforced with 0.1) Type I A and 2 Type II A strips in thepresent study are compared with the $49 values reported +11- on stone dust reinforced with 0.2 geogrid micro mesh #; for $ D 1.0 m for different A>$ ratios. The si/es of # used by them


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were &0 mm F &0 mm and )0 mm F )0 mm. The typical variation of $49 with A>$ ratio is shown in ?ig.*. A study of this figure indicate that:

1. The $49 values are comparable when 2 Type II A strips and 0.2 # were added to thesand.

2. The $49 values are sufficiently low when 0.1) Type I A strips were added to sand.

?ig. * Bariation of $49 with A>$ ratio for 0.2 # 0.1) Type I A and 2 Type II A strips.

. CONCLUSIONS

Gn the basis of the results and analysis presented in this paper it can be concluded that sandwasteplastic mixtures improve the bearing capacity of granular trench and consetrench.

NOTATIONS

H Angle of shearing resistance

cH 4ohesion

1f a8or principal stress at failure

& inor principal stress

$49 $earing capacity ratio

49 %seudocohesion of reinforced sand42 4ohesion of clayA !idth of granular trench$ !idth of the footing6f 6epth of foundation below ground level.# #eogrid micro mesh

RE-ERENCES

+1- $enson 4.5. and Khire .. 1'',;. 9einforcing sand with strips of reclaimedhighdensity polyethylene. Journal of Geotechnical EngineeringBol. 121 =o. , pp. 3&33)).+2- $ishop A.! and 5en(el 6.J 1'*2;. The measurement of properties in the triaxial test. 7dward Arnold %ublishers @td @ondon.

+&- $ueno $. de "ou/a 1'';. The echanical response of reinforced soils using short randomly distributed plastic strips. Recent developments in Soil and Pavement Mechanics.Almeida ed.;


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$al(ema 9otterdam I"$= '0),1033)1 pp.,01,0. +,- 6utta . 7d; 1'';. Waste disposal in Engineered landfills. =arosa %ublishing 5ouse =ew 6elhi pp. &,.

+)- 9an8an #opal Basan 9.. E 4haran 5.6. 1''*;. %robabilistic analysis of randomly distributed fiberreinforced soil. Journal of Geotechnical Engineering Bol. 122 =o. * pp. ,1',2*.+*- #ray 6.5. E aher .5. 1'3';. Admixture stabili/ation of sand with discrete randomly

distributed fibers. Proc. X nt. !onf. on Soil Mech. "ound. Eng. 9io de Janeiro $ra/ilpp. 1&*&1&**.

+- #ray 6.5. E Ghashi 5. 1'3&;. echanics of fiber reinforcing in sand. Journal of Geotechnical Engineering Bol. 10' =o. & pp. &&)&)&.+3- #ray 6.5. and Al9efeai. T 1'3*;. $ehavior of fabricvs fiberreinforced sand. Journal of

Geotechnical Engineering Bol. 112 =o. 3 pp. 30,320.

+'- adhav .9. and Bit(ar %.%. 1'3;. "trip footing on wea( clay stabili/ed with a granular trench of pile. !anadian Geotechnical Journal Bol. 1) pp. *0)*0'.+10- "chlosser ?. and @ong =.T. 1',;. 9ecent results in ?ranch 9esearch on reinforced earth. Journal of the !onstruction #ivision Bol. 100 #T& pp. 2&&2&.+11- "hamsher ?.5 1''2;. Ground improvement $ith oriented geotextiles and randoml% distri&uted

geogrid micro mesh. unpublished %h.6 thesis IIT 6elhi India.


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Ground Improvement Rao Dutta

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