Group Interaction

Section 8:

Group Interaction

Group Interaction

Is the stiffness from a Modulus Test the same as the

upper zone stiffness of group?

Group Interaction

Because of stress overlap, we might think that group

settlement > modulus test settlement

Stress

overlap

Let’s look at the data – Utah site: v. soft clay

Group Interaction - Load Tests

On a per-pier basis, modulus test results = group results

0 1000 2000 3000

Load (kN)

250

200

150

100

50

0

Settlement (m

m)

Measured Load From Pier Group

Measured Single Pier Load Multiplied by 5

1 kN = 0.225 kips

1 mm = 0.039 in.

versus

Group Interaction – Load Tests

Load test data: Iowa site, Short and Long Piers – Soft Clay

On a per-pier basis, modulus test results = group results

Short piers Long piers

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.0 4.0 8.0 12.0

Stress (ksf)

Deflection (inches)

Test Pier

Pier Group0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.0 4.0 8.0 12.0

Stress (ksf)

Deflection (inches)

Test Pier

Pier Group


Load test data: Lacrosse WI – Loose Sand

On a per-pier basis, modulus test

results = group results

-2

-1.5

-1

-0.5

0

0 20 40 60 80Geopier Stress (ksf)

Deflection (in)

Modulus Test

Full-Scale Load

versus

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3/1/

06

3/31

/06

4/30

/06

5/30

/06

6/29

/06

7/29

/06

8/28

/06

9/27

/06

10/2

7/06

11/2

6/06

12/2

6/06

1/25

/07

2/24

/07

3/26

/07

4/25

/07

5/25

/07

6/24

/07

Date

Sett

lem

ent

(in

) )

STA 11142+00 STA 11162+00

STA 11154+00 STA 11158+00

STA 11146+00 STA 11174+00

STA 11134+00 STA 11178+00

Settlement Criterion = 2-inch

End of Fill Placement


Load test data: Wichita RR wall – clay fill

On a per-pier basis,

modulus test results =

group results

Deflection from

modulus test

The answer to the question is found in cavity expansion

soil mechanics

Group Interaction – Soil Mechanics (theory)

Stress path

(elastic regime)

Start with normally consolidated soil:

Increase radial stress. Elastic theory:

tangential stress decrease = radial

stress increase

σσσσ’z

σσσσ’r

σσσσ’θθθθ

σσσσ’zσσσσ’r

σσσσ’z

σσσσ’θθθθ

σσσσ’θθθθ σσσσ’r

Stress paths during cavity expansion

Group Interaction – Soil Mechanics (theory)

Elastic stress path

until yield surface

Stress path

(plastic)

Increase radial stress some more. Stress

path moves up and to the left

Increase radial stress even more. Stress

path moves up the failure surface

σσσσ’z

σσσσ’r

σσσσ’θθθθ

σσσσ’θθθθ σσσσ’zσσσσ’r

σσσσ’rσσσσ’θθθθ

Group Interaction – More theory

So…. if we can measure lateral stresses, we can

test the measurements against theory to “see”

the stress zones

Plastic theory says that the

dissipation of radial

stress should decay

with radial distance as:

Elastic theory says that the

dissipation of radial

stress should decay

with radial distance as:

1

Log R

Log

Radial

stress

1 1

1- Ka 1

Extrapolate measurements to

find pressure on zero thickness

blade = in-situ lateral stress

Group Interaction – Stress Measurements

Log pressure

Group Interaction – Stress Measurements

Plastic and elastic zones recognizable

1

1- Ka

1

1

End up with three stress zones around the RAP:

Group Interaction – Theory to reality

RAP

Elastic

zone

Elastic

zone

“Plastic

Zone”

“Plastic

Zone”

Passive uplift zone

6 ft

Radial pressure in plastic zone

horizontally preloaded to 120 kPa

Start with simple (axisymmetric) model of individual piers

Group Interaction – Numerical Modeling

Applied Compressive Load per Pier [kN]

0 50 100 150 200 250 300 350 400

Settlement [m

m]

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Measured (P1)

Measured (G1)

Computed (P1)

Computed (G1)

(a)

Pier length: L = 2.79 m

Fcapacity

= 840 kN

210 kN

9.5 mm

Seating load

Applied Compressive Load per Pier [kN]

0 50 100 150 200 250 300 350 400 450 500

Settlement [m

m]

-80

-70

-60

-50

-40

-30

-20

-10

0

Measured (P2)

Measured (G2)

Computed (P2)

Computed (G2)

(b)

Pier length: L = 5.10 m

220 kN

Fcapacity

= 880 kN

10 mm

Seating load

Achieve good correspondence

with measured field results –

parameter values appropriate

(ISU and KU)

FLAC3D 3.10

Itasca Consulting Group, Inc.Minneapolis, MN USA

©2006 Itasca Consulting Group, Inc.

Step 373686 Model Perspective11:59:00 Sun Oct 07 2007

Center: X: 1.900e-001 Y: 1.900e-001 Z: -1.850e+000

Rotation: X: 360.000 Y: 0.000 Z: 0.000

Dist: 3.890e+001 Mag.: 3.81Ang.: 22.500

Surface Magfac = 1.000e+000 Live mech zones shown

Displacement Maximum = 8.509e-002 Linestyle



FLAC3D 3.10



Step 1251206 Model Perspective22:41:07 Sun Oct 07 2007

Center: X: 2.813e-001 Y: 1.391e-001 Z: -1.627e+000

Rotation: X: 40.000 Y: 0.000 Z: 40.000

Dist: 3.898e+001 Mag.: 2.44Ang.: 22.500






Surface


Then build 3D model of pier group

FLAC3D 3.10



Step 11660 Model Perspective15:06:50 Mon Oct 15 2007

Center: X: -1.048e-002 Y: 1.674e-001 Z: -7.000e+000

Rotation: X: 90.000 Y: 0.000 Z: 0.000

Dist: 3.898e+001 Mag.: 4.77Ang.: 22.500


Velocity Maximum = 8.946e-006 Linestyle

Expand each cavity

incrementally then apply

vertical foundation load


Achieve good correspondence with measured group

deflection for both short piers and long piers

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

0 200 400 600 800 1000 1200 1400 1600 1800

Applied vertical load (kN)

Dis

pla

cem

en

t a

t to

p o

f p

iers

Field

Current

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

0 200 400 600 800 1000 1200 1400

Applied vertical load (kN)

Dis

pla

ce

men

t at

top

of

pie

rs (

mm

)

Field

Current

Short piers in a group Long piers in a group


Review stress paths – increasing lateral stress makes the

soil stiffer; principal stress reversal allows you to

move away from yield surface during loading

Single pier

-120

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

0 20 40 60 80 100 120

mean stress, p' (kPa)

shear stress, q' (kPa)

Method 1

Method 2

-50

-40

-30

-20

-10

0

10

20

30

40

50

0 10 20 30

mean stress, p' (kPa)

shear stress, q

' (kPa)

Method 1

Method 2

Pier groupCavity

expansion:

20 kPa

Cavity

expansion:

45 kPa

Load

towards yield

surface

Load away

from yield

surface


Influence of lateral stress on preconsolidation pressure

In simpler terms: when you laterally preconsolidate

the soil, you increase the preconsolidation

pressure and increase the soil stiffness

0.55

0.60

0.65

0.70

0.75

10 100 1000

log(σ'v) - kPa

Void ratio, e

K=1.0

K=1.5

K=2.0

K=2.5

K=3.0

Data from the isotropic

consolidation test

New virgin

curvesVolume change

during lateral

consolidation

σ'v=250 ; ∆σ'v=0

Group Interaction

Lateral stress allows buildings like this to be supported

on RAP foundations (Marquee Towers, Irvine, CA)

Section 9:

Resistance to

Lateral Loads

SEISMIC (AND WIND) DESIGN

Lateral Load Resistance

PRESSUREBEARING

MATRIX SOIL

INERTIAL LOADS

GEOPIER

ELEMENT

PRESSURE

PRESSURE

EARTH

BEARINGGEOPIER

PASSIVE

UPLIFT

ANCHOR

RESISTANCESLIDING

DISPLACED

FOUNDATION

Mechanisms identical to

conventional spread footings:

1. Passive earth pressure

adjacent to footing.

2. Friction at the base

of the footing.

PRESSUREBEARING

MATRIX SOIL

Sliding Resistance

Fg FgFm


1. Friction between RAP element and footing:

Fg = fg Ag

2. Friction between matrix soil and footing:

Fm = fm Am

3. Total sliding resistance at footing Base, F

F = Fg + Fm

PRESSUREBEARING

MATRIX SOIL

Sliding Resistance

RAP unit frictional resistance:

fg = qg tan φφφφ′′′′g

Matrix soil unit frictional resistance:

fs = qm tan φφφφ′′′′m

Normal stress on RAP element:

qg = {qRs / [Ra Rs +1 - Ra]}

Normal stress acting on the matrix soil:

qm = qg / Rs


Sliding Resistance

Total sliding resistance (F) at footing base:

Typical RAP friction angle = 48° - 52°

Typical factor of safety = 2.0

Composite unit friction resistance (f) for footing:


( )( )asa

magas

RRR

RRRqAF

−+

−+=

1

tan1tan '' φφ

( )( )

asa

magas

RRR

RRRf

−+

−+=

1

tan1tan '' φφ

Section 10:

Control of

Uplift Loads

Uplift Resistance

Uplift loads are applied to footings

during a structure’s response to

lateral loads.

Uplift anchors are installed at the

bottoms of RAP elements to resist

uplift loads.

Uplift capacity calculations assume

the formation of a cylindrical failure

surface at the perimeter of the

element.


Load Test Uplift Element

at UC Davis Production Uplift Elements

Uplift Resistance


• Uplift tendon - 75 ksi Threadbar is – Oversized

– Galvanized

– Asphalt Coated

– Heated Poly Sleeve

• Uplift Base Plate– Oversized

– Galvanized

– Sealed with spray-on poly-urethane coating

• Threadbar to base plate bolted connection is sealed with poly-urethane coating

• Electrically isolate uplift from footing rebar.

• Cathodic Protection if required.

Corrosion Protection


After Installation

Footing PreparationUplift Resistance


Uplift Resistance

Drained Behavior

fs = σσσσ′′′′h tan φφφφ′′′′m

σσσσ′′′′h = Kp σσσσ′′′′v ≤≤≤≤ 2500 psf

Kp = tan2 (45 + φφφφ′′′′m)

σσσσ′′′′v = γγγγ′′′′ (Df + Hs/2)

(See shaft length checks)

Df

Hs

Undrained Behavior

fs = c

c = Undrained shear

strength


Uplift Load Resistance: sss AfQ =

Uplift Load Test

Load Test Pier

Cribbing

Compression

RAP

Element

13 feet

6.5 feetW-Beam

W-Beam

100 ton jack


Uplift load test results


0.0

0.5

1.0

1.5

2.0

0 20 40 60 80 100

load, (kips)

defl

ecti

on

, (i

n)

11 Load Cycles

per test event

1x 30 kips = 50%

1x 45 kips = 75%

4x 60 kips = 100%

2x 90 kips = 150%

3x 120 kips = 200%

Time to complete 1

test event ~ 1 hour

30 minutes

Second test event

run 2 hours after

completion of first0

20

40

60

80

100

120

140

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Vertical Displacement (inches)

Perc

en

t o

f A

llo

wab

le C

ap

acit

y

First Load Cycle

Second Load Cycle

Cyclic Load Testing: 33-inch by 15-foot deep Geopier Uplift Element

67%

33%

100%

133%

200%

167%

Allowable Uplift Capacity = 60 kips

Axia

l U

plift

Lo

ad

(kip

s)

.

Notice no break in

stiffness after 22

cycles

Cyclic Uplift load test results


Group uplift


B B

W W FsHs~4

1

Granular Cohesive

See Technical Bulletin No. 3

SEISMIC / WINDBay Area Rapid Transit Parking Garage,

Walnut Creek, CA

- 8-story parking garage

- Pmax = 2,300 kip = 1045 Ton

- Uplift loads > 1,500 kip = 680 Ton

- 30-inch diameter Geopier

- Pier lengths: 14 – 20 ft

- 4.3 - 6 meters

- 6-story Hospital

- Pmax = 1,260 kip = 573 Ton

- Uplift loads = 1,080 kip = 490 Ton

- 30-dia. Geopier up to 22 ft

- 6.7 meters

- Sustained direct hit from

Hurricane Rita in 2005!

SEISMIC / WINDMedical Center of Southeast Texas,

Port Arthur, TX

Section 11:

Liquefaction Mitigation

SEISMIC DESIGN

Liquefaction - What is it?

1. Soil liquefaction occurs when loose deposits of

saturated sand are subject to shaking. Liquefaction

requirements include:

a. Granular soils.

b. Saturation.

c. Low relative density - contraction during

densification.

d. Ground shaking strong enough to cause

densification.

e. Ground shaking long enough to sustain pore

water pressure buildup.

SEISMIC DESIGN

Liquefaction - What is it?

2. If the level of shaking is of sufficient intensity and

duration:

a. Loose sands contract,

b. Pore water pressures increase within

the saturated deposit,

c. Effective stress then decreases

d. Causing reduction in soil shear strength.

e. Liquefaction results in both a loss of soil shear

strength and then a subsequent reduction in

soil volume as the excess pore

water pressures dissipate.

(Seed and Idriss, 1982)

SEISMIC DESIGN

Impacts of Liquefaction

1. Liquefaction causes bearing capacity failure or

excessive settlement from loss of shear strength

PRESSUREBEARING

MATRIX SOIL

INERTIAL LOADS

GEOPIER

ELEMENT

PRESSURE

PRESSURE

EARTH

BEARINGGEOPIER

PASSIVE

UPLIFT

ANCHOR

RESISTANCESLIDING

DISPLACED

FOUNDATION

2. Subsequent settlement occurs from the

dissipation of excess pore pressure.

3. Piles are subject to excessive

bending moments from inertial

forces combined with the loss of

supporting liquefied materials.

Rammed Aggregate Pier systems reduce the

potential for liquefaction:

1. RAPs are too dense to liquefy.

2. Increase in horizontal stress increases liquefaction

resistance.

3. Drainage.

4. Densification (requires clean sand).

5. Shear stress distribution.

PRESSUREBEARING

MATRIX SOIL

INERTIAL LOADS

GEOPIER

ELEMENT

PRESSURE

PRESSURE

EARTH

BEARINGGEOPIER

PASSIVE

UPLIFT

ANCHOR

RESISTANCESLIDING

DISPLACED

FOUNDATION

SEISMIC DESIGN


SEISMIC DESIGN


1. Shear stresses induced in the soil mass and Geopier elements

are proportional to shear stiffness (stiff springs attract load).

2. The ratio of applied shear stress that is resisted by the existing

soil (ττττs) to the free-field shear stress (ττττ):

APPLIED

SHEAR STRESS

MATRIX SOIL

SHEAR STRESS

RESISTANCE

GEOPIER SHEAR

STRESS RESISTANCE

GEOPIER

ELEMENT

ZONE OF

HORIZONTAL

STRESS INCREASE

Figure 3. Reduction of Liquefaction Potential

ττττs

ττττ====

1

(1 - Ra + Ra Rs)

APPLIED

SHEAR STRESS

ZONE OF

HORIZONTAL

STRESS INCREASE

RAPττττm

ττττgττττm < ττττ < ττττg

ττττ

SEISMIC DESIGN


3,100+ Impact® piers installed

SEISMIC / LIQUEFACTIONMoran Asian Garden, Westminster, CA

Impact Pier Construction

SEISMIC / LIQUEFACTIONMoran Asian Garden, Westminster, CA

- 2,700,000 ft2 shipyard development

- Up to 3,100 psf slab pressures

- Improvement of soft clay and intermittent SP/SM

- Foundation support & liquefaction mitigation for

0.8g seismic event

- Over 48,000 piers

- Spacing of 6.5 o-c

SEISMIC / LIQUEFACTIONBogazici Shipyard, Altinova, Turkey

SEISMIC / LIQUEFACTIONBogazici Shipyard, Altinova, Turkey

Section 12:

Stabilization of Slopes,

Embankments & Walls

Shear Strength

How do RAP systems work?

Replace weak soil with stronger /stiffer material

Engineering basics

Now we have a stronger “upper zone” and

an unimproved “lower zone”

Upper

zone

Lower

zone


Focus on “upper zone” (for the rest of this paper)

Engineering basics

Push down on footing, the stiff element (pier)

takes more of the load


The strength and stiffness of the pier determined using

a Modulus Test which gives you a spring constant

Engineering basics

0.00

0.25

0.50

0.75

1.00

0 10 20 30 40

• Deflection = 0.25-inch

• kg = stress / deflection = 500 pci

Design

Top deflection

Geopier Stress (ksf)

Defl

ecti

on

(in

)

Telltale deflection


The strength of the pier depends on only two factors:

• The friction angle of the RAMMED aggregate, and

• The EFFECTIVE horizontal stress in the soil

Engineering basics

σσσσ

ττττ

σσσσ3 σσσσ1σσσσ′′′′r,lim qult,g

φφφφg = 49°- 52°

qult,g = σσσσ′′′′r,lim tan2 (45 + φφφφg/2)qult,g

σσσσ′′′′r,lim


The strength of the pier is a key ingredient for stability

Engineering basics

Normal stress (kPa)

0 100 200 300 400 500 600 700 800 900 1000

Shear stress (kPa)

0

100

200

300

400

500

600

700

800

900

1000

Single Ring - Fox and Cowell (1998)

Triaxial Tests - White et al. (2002)

Single Ring - This study

Double Ring - This study

Single Push Test - This Study

φ = 52o

φ = 52o

c = 51.3 kPa

φ = 45o

φ = 50o

Higher friction angle =

greater Factor of Safety

The higher the friction angle –

• The more load you can put on the piers prior to

bulging

Friction Angle of Rammed Aggregate

2. The more influence the piers have in improving

stability

Iowa State UniversityPhoto courtesy of Dr. Nat Fox

Friction Angle of Rammed Aggregate

y = 0.750x + 19.794

R2 = 0.962

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000

pf = (σv + σh)/2 (kPa)

qf = (

v - h)/2 (kPa)

1A

1B

2

3

4

5

6

7A

7B

8

9

10A

10B

11A

11B

SLOPE STABILITY

Global stabilization to control slope movements

Slopes and embankments are subject to failure if the

foundation materials are not sufficiently strong to

resist shearing caused by new embankment/wall fill

placement. In most cases, shearing occurs on

circular surfaces.

SLOPE STABILITY

The installation of RAP elements increases the

shearing strength of the foundation soils.

SLOPE STABILITY

RAP Contributions

ττττcomposite = ccomposite + σσσσ′ tan φφφφcomposite

RAP aggregate behaves as a frictional material with a

high friction angle (typically 50 degrees) and a zero

cohesion intercept. The composite shear strength

(ττττcomposite) of RAP-reinforced soil is expressed as:

SLOPE STABILITY

Composite shear strength parameters:

Ra = RAP percent area coverage

ccomp = Ra*cg + (1-Ra)*cm

φφφφcomp = arctan [Ra*tan(φφφφg)+(1-Ra)*tan(φφφφm)]

SLOPE STABILITY

Weighted average of

matrix soil and RAP

shear strengths

Example calculation:

For Ra = 0.2, cm = 500 psf, φφφφm = 0°°°°

ccomp = 0.8*500 = 400 psf

φφφφcomp = arctan [0.2*tan(50°°°°)] = 13.4°°°°

Weighted average of

matrix soil and RAP

shear strengths

SLOPE STABILITY

What’s missing?.......

Stress concentration to

stiff RAP elements

SLOPE STABILITY

0

5

10

15

20

25

30

35

40

45

1 2 3

Stress Concentration

Ratios (I-15 project)Pressure

plates

4030

Stress concentration

SLOPE STABILITY

ccomp =

φφφφcomp = arctan

Typical Rs factor for stability =

1 to 5 (flexible structures)

Including stress

concentration to stiff

RAP elements

1- Ra

RaRs-Ra+1cm

1 - Ra

RaRs-Ra+1tan(φφφφm)

Rs Ra

RaRs-Ra+1tan(φφφφg) +

RsRa

RaRs-Ra+1cg +

SLOPE STABILITY

An example….

For Ra = 0.2, Rs = 3,

cm = 500 psf, φφφφm = 0°°°°

27.113.40φφφφ (degrees)

286400500c (psf)

RAP

(with conc.)

RAP

(no conc.)

No RAPParameter

Value

SLOPE STABILITY

Slope stability calculations are performed using the

composite shearing strengths for the RAP-reinforced

layers.

SLOPE STABILITYStress Concentration – where does it go?Why is this important?

Stress concentration improves effectiveness for stability

Comparisons with FEA show that stability calculations

including SCR factors provide accurate results

Global stability

• High friction angle

• Increase in composite shear resistance

• Increases global stability and slope stability

SLOPE STABILITY US71 SLOPE STABILIZATION

KROTZ SPRINGS, LA

US71 SLOPE STABILIZATION

KROTZ SPRINGS, LA


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Extent of initial movement


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Continued movement

(after heavy rains)


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Continued movement

(after heavy rains)


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Soil Conditions

40 ft

30 ft

20 ft

10 ft

B-2 B-1

CL/CH

Clay Fill

0 ft

US71

Roadway


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

InstabilityInstability

Inclinometer Data

10’

20’

20’

10’

I-1

I-2


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Modify strength parameter values to arrive at FS = 1

FS = 1


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Install Geopier elements to intersect

critical circle and increase FS

Geopier Zone

FS > 1.3


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Cross-section of RAP zone


KROTZ SPRINGS, LA


KROTZ SPRINGS, LAUS71 SLOPE STABILIZATION

KROTZ SPRINGS, LA


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA


KROTZ SPRINGS, LA

Post-Reinforcement Inclinometer Monitoring

DownslopeUpslope

No movement 3 months after construction

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

-25 -20 -15 -10 -5 0 5 10 15 20

Lateral Displacement (mm)

Depth (m)

10/18/05

01/18/06

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

-25 -20 -15 -10 -5 0 5 10 15 20 25

Lateral Displacement (mm)

Depth (m)

10/18/2005

01/18/06

Inclinometers show no long-term movement

of reinforced zone.

Section 13:

Support of

Embankments and Walls

MSE walls or retaining walls

Pressure distributions beneath MSE walls and

conventional retaining walls

SUPPORT OF EMBANKMENTS

AND WALLSMSE walls or retaining walls

Allowable

bearing

pressure

without RAP

system

Install RAP elements here to

satisfy bearing capacity


AND WALLS

MSE walls or retaining walls

RAP installation increases allowable

bearing pressure


AND WALLS

Design approach

Terzaghi lower

bound bearing

capacity approach

with upper bound

correction factor

(Barksdale and

Bachus 1983; Hall et

al. 2001)


AND WALLS

Hooke’s Law: S =

q = Applied pressure from embankment

Iσσσσ = Influence factor (~1.0 for area loading)

H = Height of reinforced zone

Ecomp = Composite stiffness in reinforced zone

q Iσσσσ H

Ecomp

Settlement in reinforced zone


AND WALLS

Ecomp = (1-Ra) Em + Ra * Eg

Ra = RAP area coverage ratio

Em = Matrix soil elastic modulus

Eg = RAP elastic modulus

(established with modulus test)

Composite stiffness using weighted average


AND WALLS

Settlement rate increase from:

Arching of

stresses to

elements

Radial drainage


AND WALLS


AND WALLS

See Tech Bulletin 6 for:

• Settlement control

• Radial drainage

• Time rate of settlement

Increase in settlement rates

• Afforded by stress concentration and

radial drainage

• Use of Han and Ye research to predict

settlement rates

• Settlement occurs in days not months


AND WALLS

Central Corridor Railroad Grade Separation

Wichita, KS

Photo Courtesy of The Neel Company


Wichita, KS

T-Wall Image Courtesy of The Neel Company

Phase 2Phase 4

Soft to Stiff Clay /

Fill

Sand

8 – 27 ft

26 ft


Wichita, KS

Geotechnical Design Considerations

• Settlement: excessive total and differential

settlement

• Time rate of settlement: Slow clay consolidation

could cause track maintenance issues

• Bearing capacity: Insufficient bearing in clay & fill


Wichita, KS

T-Wall Image Courtesy of The Neel Company

Phase 2Phase 4

Sand

26 ft


Wichita, KS

• Over 6,300 Geopier elements installed

• Piers spaced between 8 and 10 feet on-center

• Increased bearing capacity (and stability)

• Maintained RR traffic during construction

• Limited total settlement to 2” or less

Geopier System Solution


Wichita, KS

HNTBGeotech Eng:

Dondlinger & Sons

Construction Co.Contractor:

TranSystemsProject Manager:

City of WichitaOwner:

SIENNA PARKWAY MSE WALL

MISSOURI CITY, TX

SIENNA PARKWAY MSE WALL

MISSOURI CITY, TX

• Support of 31 ft tall MSE wall on Sienna Parkway

• Geopier RAPs installed at 7 feet o/c.

• 490 Geopier RAPs installed in < 3 weeks.

PICARDY AVENUE MSE WALL SUPPORT

BATON ROUGE, LA


BATON ROUGE, LA

RAP solution using Geopier® system


BATON ROUGE, LA


BATON ROUGE, LA

• 37 ft tall MSE wall

• Soft to stiff clay

• Geopier elements at

5.25 to 8 feet o/c.

• Performed work on

multiple phases

RAP solution using Geopier® system

Group Interaction

Documents

Transcript of Group Interaction