Sustainable Slope Stabilization using Recycled Plastic Pin

Sahadat Hossain, Ph.D., P.E.

Sadik Khan, Ph.D., P.E.

Shallow Landslides in Highway Slopes

Shallow Landslides in Clay Soil

Expansive Clay in US

Legend:

Red: Clay having high swelling potential

Blue: Less than 50% of clay contents having high

swelling potential

Orange: Clay content having slight to moderate swelling

potential

Green: Less than 50% of clay contents having slight to

moderate swelling potential

Brown: Little or no swelling clay

Yellow: Insufficient data

Problems of Expansive Clay

Displacement

ShearStress

Peak O-C

Fully SoftenedPeak N-C

Residual

0.6

0.7

0.8

0.9

1

1.1

1.2

0 1 2 3 4 5

Vo

id R

atio

, e

Number of wet-dry cycle

Change in Void Ratio

Initial Condition

Final Condition

0

20

40

60

80

100

0 2 4

% C

han

ge in

Co

hes

ion

No of Wet Dry Cycle

Changes in Cohesion

0

10

20

30

40

50

0 2 4

% C

han

ge in

Fri

ctio

n A

ngl

e

No of Wet Dry Cycle

Changes in Friction Angle

Fact About Plastic Waste

• 50 Billion Water Bottle end up in US Landfill Each Year

• It may take 700 years to decompose plastic bottles

• Ecosystems and wildlife are negatively impacted by plastic

debris.

What is Recycled Plastic Pin?

• Recycled Plastic Pin (RPP)

• Mainly Polymeric Materials

• Fabricated from Recycled Plastics

• Commercially Available

• RPP Reduces Waste Volume

• Resistant to Biological Exposure

Structural Properties of RPP

Specimen

Batch

No of

Specimens

Tested

Nom. Def.

Rate

(mm/min)

Flexural

Strength

(MPa)

Secant

Flexural

Modulus

E1%

(MPa)

Secant

Flexural

Modulus

E5%

(MPa)

A1 13 - 11 779 662

A4 3 4.27 18 1,388 -

A5 3 5.74 11 711 504

A6 4 3.62 10 634 443

B7 1 4.05 9 544 425

0

1

2

3

4

5

0 1 2 3 4 5

σ(

ksi

)

ε ( inch/inch )

3 point bending test results of RPP

0.5 kips/min 2.7 kips/min 4.9 kips/min

Ref:

Bowders et al., 2003; Hossain et al., 2017

Stabilization of Slopes using RPP

Factor of Safety:

Without Reinforcement

FS = Mr/Md

Factor of Safety:

With Reinforcement

FS = (Mr+∆Mr)/Md

Test Site

Test Site is located over highway US 287, near St. Paul overpass close to Dallas, Texas

Resistivity Profile: RI-1

Resistivity Profile: RI-2

0

10

20

30

40

50

60

70

80

20 40 60 80

Pla

stic

ity

In

dex

Liquid Limit

Plasticity Chart

BH-1

BH-2

BH-3

Site Investigation

Displacement

ShearStress

Peak O-C

FullySoftened

Peak N-C

Residual

Reinforced Section 1: FS = 1.43

Reinforced Section 2: FS = 1.48

Reinforced Section 3: FS = 1.54

Soil

Type

Friction

AngleCohesion

Unit

Weight

Elastic

Modulus

φ c ϒ E

- ◦ psf pcf psf

1 10 100 125 100000

2 23 100 125 150000

3 15 250 130 200000

4 35 3000 140 250000

Back Analysis of Unreinforced Slope: FS = 1.05

Soil 4

Soil 3

Soil 2 Soil 1 Back Calculated Soil Parameters

Design of Slope Stabilization

RPP Layout

• Equipment: Klemm 802 Drill Rig

• Hammer Type: KD 1101

Installation

Installation

• Rain Gauge

• Instrumented RPP

• Surveying

• Inclinometer

• Moisture Sensor

• Water Potential Probe

Instrumentation

0

2

4

6

8

10

12

14

16

18

20

0 50 100 150 200 250

Set

tlem

ent

(in

)

Distance along Roadway (ft)

Total Settlement of at the crest of US 287 slope

5.6.12 5.6.12 6.6.12 7.13.12 8.3.12 9.8.12 10.6.12 11.10.12

12.13.12 1.10.13 2.9.13 3.7.13 4.5.13 5.20.13 7.1.13 8.2.13

Settlement at Crest

Site Photo

17

R. Section 1

Control Section

Control Section 2

R. Section 3

Settlement: 15 in

Settlement: 9 in

-1

0

1

2

3

4

0

1

2

3

4

5

7/16/

11

9/16/

11

11/16/

11

1/16/

12

3/16/

12

5/16/

12

7/16/

12

9/16/

12

11/16/

12

1/16/

13

3/16/

13

5/16/

13

7/16/

13

Dis

pla

cem

en

t (i

nch

)

Rain

fall

(in

ch

)

Date

Comparison of Horzontal Movement at US 287 Slope

Rainfall 2.5 ft-Inc1 2.5 ft-Inc 3

Horizontal Movement

0

20

40

Mo

istu

re

Co

nte

nt

(%)

-20000

-16000

-12000

-8000

-4000

0

Mat

ric

Suct

ion

(p

sf)

-0.5

0

0.5

1

1.5

2

Jul-

11

Aug-1

1

Sep

-11

Oct

-11

No

v-1

1

Dec

-11

Jan

-12

Feb

-12

Mar

-12

Ap

r-12

May

-12

Jun

-12

Jul-

12

Aug-1

2

Sep

-12

Oct

-12

No

v-1

2

Dec

-12

Jan

-13

Feb

-13

Mar

-13

Ap

r-13

May

-13

Jun

-13

Jul-

13

Aug-1

3

Ho

rizo

nta

l D

isp

lacem

en

t (i

nch

)

Date

2.5 ft-Inc1 6.5 ft-Inc 1 10.5 ft-Inc 1 20.5 ft-Inc 1

Rainfall

M/C

Matric Suction

Displacement

0

4

8

Rain

fall

(i

nch

)

Rainfall Average Rainfall Total Rainfall

Comparison of Rainfall, Moisture Content, Matric Suction and Hor. Displacement

Comparison with Temperature

-0.5

0

0.5

1

1.5

2

40

60

80

100

120

140

1/1/12

2/1/12

3/1/12

4/1/12

5/1/12

6/1/12

7/1/12

8/1/12

9/1/12

10/1/12

11/1/12

12/1/12

1/1/13

2/1/13

3/1/13

4/1/13

5/1/13

6/1/13

7/1/13

8/1/13 D

isp

lacem

en

t (i

nch

)

Dail

y H

igh

est

Tem

pera

ture

(F

)

Date

Comparison of Horizontal Movement with Temperature

Daily Highest Temperature 2.5 ft-Inc1 2.5 ft-Inc 3

Desiccation Crack

(Dry Period)

No Cracks

(Wet Period)

News Clip!!

Comparison of Performance

Northbound and Southbound (Reinforced) Slope

Failure Location 3

Failure Location 4

Failure Location Time

Failure Location-1 October 2013

Failure Location -2 October 2013

Failure Location-3 June 2015

Failure Location-4 June 2015

Google Earth Image Comparison

Northbound (Control) and Southbound (RPP Stabilized) Slope

Imagery Date: 1/29/2016Imagery Date: 7/14/2015

Imagery Date: 4/10/2013Imagery Date: 6/12/2011

RPP Reinforce Area RPP Reinforce Area

RPP Reinforce Area RPP Reinforce Area

Comparison of Performance

Northbound and Southbound (Reinforced) Slope

Comparison of Performance

Northbound and Southbound (Reinforced) Slope

Traditional Repair

Northbound and Southbound (Reinforced) Slope

01

23456

Pre

cip

itati

on

(in

ch

)

Date

Failure of Northbound Control Slope After Repair

Northbound (Control) and Southbound (RPP Stabilized) Slope on 1/29/2016

Imagery Date: 7/14/2015

RPP Reinforce Area (No Sign of

Failure)

Deep Seated Failure after repair

Recently Published Book

Site Investigation

• Conventional Investigation Methods:

- Provides Information at Certain Points

- Not a General View of Site

- Expensive

Electrical Resistivity Imaging

•An electric current is injected into the ground

through two electrodes

•The resulting potential is measured between two

other electrodes

•Injected current and resulting voltage (potential)

is measured and “apparent resistivity” is calculated

Potential Advantages of ERI

Potential benefits of RI:• Continuous image of the subsurface

• Reduces of risk and liabilities

• Cost-effective design solutions

• Both for forensic and geo-hazard investigation

BH-1 BH-2

BH-2BH-1

Case Studies on the Application of Resistivity Imaging

• Several Case Studies highlighting the applications of RI in MSE wall, slope failure investigation,

pavements, tunnels, Unknown Foundations, Landfills, Ground Water flow and Cave Detection

Line 1

Line 2

Line 3

Slope Failure Investigation Investigation of Seepage

Book in Press

Site Investigation using Resistivity Imaging

Sahadat HossainGolam KibriaSadik Khan

Bore Hole 1 Bore Hole 2

Perched Water Zone 1 Perched Water Zone 2 Resistivity Imaging in MSE Wall Dr. Sadik Khan, P.E.

Assistant Professor

J00797693@jsums.edu

Phone: 601-979-6373

Dr. Sahadat Hossain, P.E.

Professor

hossain@uta.edu

Phone: 817-272-3577

Dr. Golam Kibria, P.E.

gkibria@ariasinc.com

Phone: 682-203-7611

Tentative Publication Date: September, 2018

Publisher:

CRC Press, www.crcpress.com

The book will be available in Amazon.com both in printed and

kindle version

Thank You