Geotechnics of Solid Waste Landfillsfaculty.engineering.asu.edu/kavazanjian/wp-content/uploads/2011/07/... · 10th Annual Sowers Lecture and Symposium State of the Practice Lecture

10th Annual Sowers Lecture and SymposiumState of the Practice Lecture

Geotechnics of Solid Waste LandfillsEdward Kavazanjian Jr Ph D P E G EEdward Kavazanjian, Jr., Ph.D., P.E., G.E.

Associate Professor and Interim ChairDepartment of Civil and Environmental Engineering

Arizona State University

15 May 2007

Fulton School of Engineering 1

Georgia Institute of Technology Student Center

Geotechnics of Solid Waste Landfills

U.C. Berkeley Lecture Series

J 1977 June 1977


Scope of Landfill Geotechnics

Planning: Landfill Configuration, Capacity

St bilit C t i t S t D i D iStability, Containment System Design, Drainage

Operations: Construction, Filling

Stability, Quality Assurance, Gas Control, Settlement

Closure / Post Closure: Capping, Maintenance

Stability, Settlement, Infiltration, Gas Control, Erosion, Drainage

Redevelopment: Beneficial Reuse

Foundation Design, Environmental Protection

Fulton School of Engineering

Geotechnical Issues in Landfill Engineering

Stability (Static and Seismic)W t M Li S t F d ti Fi l C Waste Mass, Liner System, Foundation, Final Cover



Settlement and DeformationWaste Mass, Final Cover, Foundations



Downdrag on Drilled Piers (Sowers, 1977)



Containment System DesignEffectiveness Integrity Drainage and FiltrationEffectiveness, Integrity, Drainage and Filtration



Lateral Earth PressuresRetaining Structure Design Risers Side Slope LinersRetaining Structure Design, Risers, Side Slope Liners



Drainage and ErosionSurface Water ControlSurface Water Control


Mechanical Properties of MSWIt’s not just a bunch of garbage(It’s an engineering material)


Waste Properties of Interest

Unit WeightStability (Seismic) CapacityStability (Seismic), Capacity

Compressibility

Capacity, Settlement

Shear StrengthgStability

Dynamic Stiffness and DampingDynamic Stiffness and DampingSeismic Response, Stability


MSW Unit WeightKavazanjian et al., 1995


In Situ Measurement of MSW Unit Weight

Large-Diameter (900 mm) Borehole Unit Weight Measurement (Matasovic and Kavazanjian, 1998)j ,


MSW Unit Weight

MSW UnitWeight FieldMeasurementsConsistentlyConsistentlyHigherthan 1995 RelationshipRelationshipfromOperators


In Situ Measurement of MSW Unit Weight

00 5 10 15 20 25

Total unit weight, kN/m3

1

2“Reliable”

20

2

3

4

5

In-SituLarge-ScaleMSW

De

pth

, m 6

7

8

Kavazanjian et al. (1995)

Unit WeightData from11 Studies(Z kk t l

40 9

10

11

(Zekkos et al.,2005)

60

(1) Santo Tirso, Portugal (Gomes et al. 2002); (2) OII, California, USA (Matasovic and Kavazanjian, 1998); (3) Azusa, California, USA (Kavazanjian et al, 1996); (4) Tri-Cities, California, USA (this study);


); ( ) , , ( j , ); ( ) , , ( y);(5) no name older landfill (Oweis and Khera, 1998); (6) no name younger landfill (Oweis and Khera, 1998); (7) Hong Kong, China (Cowland et al. 1993); (8) Central Mayne landfill, USA (Richardson and Reynolds, 1991); (9) 11 Canadian landfills (Landva & Clark, 1986); (10) Valdemingomez, Spain (Pereira et al. 2002); (11) Cherry Island landfill, Delaware, USA (Geosyntec, 2003);

MSW Unit Weight

Characteristic” Landfill Specific Unit Weight Profile

0

10

20

0 10 20 30

m

0

10

20

0 10 20 30

0

10

20

0 10 20 30

20

30

40

50

Dep

th, m

30

40

50

20

30

40

50Tri-Cities

50

60 60Azusa

00 10 20 30

00 10 20 30

00 10 20 30

60OII

0

10

20

"Younger" "older"

0

10

20

30

0

10

20

30

Dep

th, m

Cherry Island


30g older3030

Cherry Island

MSW Unit Weight

0 5 10 15 20

Total unit weight, kN/m3

Generic Characteristic MSW Unit Weight Profiles (Zekkos et al., 2005)

0

10

0 5 10 15 20

increasing compaction

20

30h,

m

low

effort and soil cover

30

40

Dept low

typical

high

OII landfill

compaction effort and soil cover

50

60

OII landfill

Azusa landfill

"Older" landfill in New Jersey


MSW COMPRESSIBILITY

Includes Mechanical and Biological (Degradation) Components(Degradation) Components

Direct MeasurementLaboratory Compression Testing

Generally Only Mechanical

Indirect MeasurementSettlement Measurements

Can Include Mechanical and Biological


Laboratory Compression TestsKavazanjian et al., 1999


SURFACE SETTLEMENT OBSERVATIONS

Require Back Analysis

Burdensome During Filling

Usually Post ClosureyPost Closure Load Testing: “Immediate” (Mechanical) Compressibility and StiffnessP Cl S l S d (C ) Post Closure Settlement: Secondary (Creep) Deformations (Includes Degradation)


Internal Settlement (Bowers et al. 2000)

1" (25 ) St l Pi1" (25 mm) Steel Pipe

2" (50 mm) PVC Sleeve

6" (150 mm) Soil for Leveling

Overburden Waste Height (Varies With Time)

Steel Plate

Waste

Geotextile

2' (.6 m) Compacted Clay Liner

1.5' (.45 m) SandGeotextile

Geomembrane


INTERNAL SETTLEMENT (Bachus and Zettler, 2003)

SETTLEMENT PROFILER


SETTLEMENT PROFILER (Bachus and Zettler, 2003)

SettlementU d Under SurchargeFillFill


Post-Closure SettlementLing at al, 1998


Compressibility SummaryCompressibility SummaryPrimary Compression

C 0 15 t 0 30CCε = 0.15 to 0.30

Unloading / Recompression

CRε / CCε = 0.05 to 0.1

Secondary Compression (Including Degradation)Secondary Compression (Including Degradation)

Depends on Climate, Moisture, Composition

CS = 0.02 - 0.18


MSW Shear Strength

Background: Low Values (e.g Singh and Murphy) Contradicted by Field Observations


MSW Shear Strength

Kavazanjian et al. (1995) Bi-Linear Envelope


MSW Shear Strength

Rumpke Landfill Failure, 1996

Mitchell (1998): Good Agreement Between Bi-Linear Envelope and Back Analysis


MSW Shear Strength

Dona Juana Failure (Hendron et al, 1999)


MSW Shear Strength

Kavazanjian, 2001 Summary Plot

Eid et al. (2000)


Strain (In)Compatability

Typical MSW Isotropic Triaxial DataGrisolia et al. (1995)


Field vs. Lab Stress PathWaste is anisotropically (K0) consolidated in the field

Kavazanjian, 2001

K0σ’V

_____σ’V


Kavazanjian, 2001

Simple Shear Stress-Strain

Backbone Curve from Cyclic Test Data

0.6

0.8

0.2

0.4

Nor

mal

Str

ess

-0 .2

0-5 0 5 10 15

Shea

r St

ress

/ N

-0 .6

-0 .4

Shear Strain (%)


Shear Strain (%)

MSW Lateral Earth Pressures

ASU Simple Shear Tests

Tekscan Pressure Pad100mm x 150 mm

605 mm x 356 mm x 229 mmSimple Shear Device


1936 pointsp

ASU K0 Lab Tests

Uncompacted (“Loose”) Waste

Compacted (“Dense”) WasteCompacted ( Dense ) Waste


K0 Consolidated Shear Strength

Zekkos (2005) Interpretation of Triaxial Data


Dynamic Stiffness and Damping

Direct MeasurementLaboratory Testing (Reconstituted Samples)

Indirect MeasurementShear Wave Velocity Measurements (Small Strain Stiffness Only)Strong Motion Measurements (Back Analysis)


Shear WaveVelocity

SASW

y

SASW Measurements at Sixat Six

California

Landfills


Back Analysis of Strong Motion Records

Only One Landfill - OIIOnly One Earthquake with More Than Small Strains

Data Still Limited to Intermediate StrainsStrains


OII Landfill


OII Landfill Strong Motion Stations

Cross Section Through the East End of the OII Landfill (after Hushmand Associates, 1994)


MSW Dynamic Properties

Back-Analysis of OII Motions


OII Lab Data Combined with Back Analysis


MSW Dynamic Properties

UCB / UT Tests

On Tri-Cities

Landfill MSWLandfill MSW

(Zekkos, 2006)

Note: ASU DSSNote: ASU DSS

Tests in Progress


Emerging MSW Properties IssueThe Effect of Moisture Content / Saturation

“Conventional” MSW Landfills in the US are Conventional MSW Landfills in the US are Relatively DryIncreasing Interest in Anaerobic Bioreactor Increasing Interest in Anaerobic Bioreactor Landfills

Wet Waste Sometimes Approaching SaturationWet Waste, Sometimes Approaching SaturationDegraded WasteExcess Pore PressuresExcess Pore Pressures


Effect of Moisture Content on MSW Unit Weight

OII

Landfill:Landfill:

Wet Waste

Saturated Waste


Bioreactor Shear Strength

18 in. Dia. Drained Direct Shear Tests on Bioreactor Waste

39o

Kavazanjian et al 2001


Kavazanjian et al., 2001

Payatas Landfill FailureGas / Pore Water Interaction?


Kavazanjian and Merry, 2005

SummaryMechanical Properties of MSW

Unit WeightOften Higher Than Assumed in PracticeOften Higher Than Assumed in Practice

Shear StrengthNot As Low As Sometimes AssumedNot As Low As Sometimes AssumedStrain to Mobilize Peak Strength Not as High as Sometimes Assumedas Sometimes Assumed

CompressibilityCan be Governed by DegradationCan be Governed by Degradation


Summary (Continued)Mechanical Properties of MSW

Dynamic Properties (Stiffness and Damping)Need More Field DataNeed More Field Data

Effect of Increased MoistureIncrease in Unit WeightIncrease in Unit WeightSame Friction Angle (33o) on an Effective Stress Basis, May Not Have CohesionStress Basis, May Not Have Cohesion

Must Always be Alert to Changes Due to:Changes in the Waste StreamChanges in the Waste StreamChanges in Operational Practices


Questions ?


Documents

Geotechnics of Solid Waste Landfillsfaculty.engineering.asu.edu/kavazanjian/wp-content/uploads/2011/07/... · 10th Annual Sowers Lecture and Symposium State of the Practice Lecture