Interface behaviour of geosynthetics in landfill cover systems under static and seismic loading

Interface behaviour of

geosynthetics in landfill

cover systems under static

and seismic loading

conditions

facoltàdi

Jean-Pierre Gourc

Nicola Moraci

Laurent Briançon

Paolo Carrubba

Ph.D. Student

Laura Carbone

Supervisors:

Co-supervisors:

Interface behaviour of geosynthetics in landfill cover systems under static and seismic loading conditions

Thesis schedule

January 2011 Mechanical behaviour of municipal

solid waste (MSW)

September 2011Geosynthetic interface problems in

landfill covers – analysis of static

loading conditions (LTHE-Université de

Grenoble)

September 2012Geosynthetic interface problems in

landfill covers – analysis of seismic

loading conditions

(IMAGE- Università di Padova)

JOINT DOCTORATE SUPERVISION

July 2010 Master’s Degree in Environmental

Engineering - Mediterranea University

of Reggio Calabria

LANDFILL – BARRIER SYSTEMS

Interface shear strenght of geosynthetics in landfill cover systems under static and seismic loading conditions

Side lining system

Cover system

Bottom barrier

LANDFILL COVER SYSTEM - Generalities

Base Layer

Gas Vent Layer

Low-Permeability

Layer

Drainage Layer

Cover Soil Layer

Waste


Schematization of landfill cap of municipal waste containment

European Union Directive 1999/31/EC

• resist to settling and localized subsidence

phenomena

• isolate the waste body from the environment

• limit the infiltration of rainwater to the waste

• minimize erosion problems

• reduce the maintenance requirement

Base Layer

Gas Vent Layer

Low-Permeability Layer

Drainage Layer

Cover Soil Layer

Waste

Cover Soil Layer

GCD

GCL

Base Layer

Waste


Different configurations of landfill cap of municipal waste containment

LANDFILL COVER SYSTEM - Generalities

Small

thickness

Easier

implementation

Economic

viability

A geosynthetic is a generic term describing a product, where at least one of

the components is made from a synthetic or natural polymer (…) used in

contact with soil and/or with other materials (…)

Geonsynthetics in landfill covers


Reinforcement Drainage Separation

BarrierErosion control

Geonsynthetics in landfill covers


Hydro-mechanical problems in MSW landfills


Stability problems of landfill cover systems


Composite barriers: one geosynthetic one function


Interfaces properties

(Sealing)

Geotextile

Geospacer

Geomembrane

(Drainage)

Veneersoil

(Filtration & Reinforcement)

Waste



soil

water

Geosynthetic

for drainage

facoltàdi

Phase 1: STATIC CONDITIONS

Inclined Plane Test Inclined Plane Test

(Laboratoire LTHE, Université de Grenoble)

Research purposes


Phase 2: SEISMIC CONDITIONS

Shaking Table TestShaking Table Test

(Laboratorio IMAGE, Università degli Studi di

Padova)

Static loading conditions – Inclined Plane Test

Soil-geosynthetic interface

EN ISO 12957-2, 2005

Inclined Plane device – LTHE, Grenoble


Geosynthetic-geosynthetic interface

Static and Dynamic interpretations of IPT

Different phases of upper box movement, for increasing inclination of the inclined plane

• “Standard Displacement Procedure” (EN ISO 12957-2, 2005)

• “Dynamic Displacement Procedure” (Gourc and Reyes Ramirez, (2004))


Inclined Plane – Test Results

Sudden sliding Gradual sliding

Different mechanisms of sliding: (a) sudden sliding; (b) gradual sliding


facoltàdi



Interface tested: woven-geotextile / smooth PVC geomembrane

ββββ50

ϕϕϕϕ50 = 25° ϕϕϕϕdyn = 19°

Sudden sliding

u50

facoltàdi



Interface tested: non woven-geotextile / smooth HDPE geomembrane

Gradual sliding

ββββ0

Force Procedure

Briançon et al. (2002) proposed a new test procedure for determining interfacial friction angle called the

“Force Procedure”

Sketch of the different steps of the “Force Procedure” test (Briançon et al., 2011)

The test consisted of three steps :

Step 1: Static stateStatic state

Step 2 : Transitory state Transitory state

Step 3: Stretched condition of the cableStretched condition of the cable


Force Procedure – Test Results


Force Procedure – Test Results


Interface tested: non woven-geotextile / smooth HDPE geomembrane

λλλλ0

λλλλlim

λλλλ0=16,5°

λλλλlim=13°

Seismic response of landfill covers

In the recent years, the seismic stability of structures that incorporate geosynthetics has

been receiving increased attention in geotechnical engineering practice

The seismic response of a whole landfill body to seismic forces is linked to the stability

of the cover system and to the shear strength at the interfaces

Geosynthetic interface shear strength can change under different loading conditions


Why???

Schematic diagram of the shaking table setup for geosynthetic-geosynthetic interfaces

Seismic loading conditions – Shaking Table Test


Seismic loading conditions – Shaking Table Test


Recorded block and table accelerations versus time for geomembrane-geotextile interface (a), and for geomembrane-

sand interface (b)

(a) (b)

Perspectives

1. Application “Force procedure” and “Displacement Procedure” to

a large range of geosynthetic-geosynthetic interfaces

revision of the European Standard

EN ISO 12957-2, 2005

comparison of test results belonged to

different test procedures

3. To test degraded materials long term geosynthetic behaviour

2. Assessment of seismic interface friction angle

lack in literature results

Thanks for your attention!!!

Interface behaviour of geosynthetics in landfill cover systems under static and seismic loading

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