An experimental investigation on the water retention behaviour of a silty soil for the computation of the lateral earth thrust on a retaining wall

Gianluca Speranza,Lyesse Laloui,Alessio Ferrari,Maxime Pousse,A Tarantino,E Ibraim

doi:10.1051/e3sconf/20199207011

Gianluca Speranza, Lyesse Laloui + Show 4 more

Open Access

https://doi.org/10.1051/e3sconf/20199207011

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Abstract

Retaining structures often interact with soils in unsaturated conditions and their performance is influenced by environmental actions. Currently, geotechnical analysis and design approaches mainly consider the soils either totally dry or totally saturated. Environmental actions, like infiltration due to rainfall, can significantly affect the lateral earth pressure of soils, influencing the performance of both temporary or permanent retaining structures. This paper deals with the investigation of the water retention behaviour of a silty soil for the computation of the soil thrust on a retaining wall during rainfall events. In this regard, the retention property of the involved geomaterial is investigated in laboratory through the combined use of high capacity tensiometers (HCT) and a dew-point hygrometer (WP4C). Considering drying and wetting paths, the experimental results are employed to calibrate the water retention behaviour for the computation of the failure shear strength of the geomaterial. The importance to monitor volume change during the characterization of the water retention behaviour of fine soils is highlighted. A series of analytical uncoupled hydro-mechanical analyses is performed to estimate the changing in the thrust of an unsaturated soil on a retaining wall under several infiltration rates. An appropriate modelling of the soil water retention behaviour is resulted to be crucial for the computation of lateral earth thrust.

Highlights

1 Introduction behaviour is resulted to be crucial for the cpormepseuntacteionofofanlayteoratlheearrtchlathyrumsti.neral, eliminating any mineralogical variability
These works have mainly provided the extension of the classical theories (i.e. Rankine’s theory and Coulomb’s method) for the estimate of the lateral earth thrust taking into account Unsaturated Soil Mechanics principles
They are plotted in terms of suction, since data referring to high capacity tensiometers (HCT) correspond to matric suction while WP4C data correspond to total suction

Summary

Introduction

1 Introduction behaviour is resulted to be crucial for the cpormepseuntacteionofofanlayteoratlheearrtchlathyrumsti.neral, eliminating any mineralogical variability. Soils with dual-porosity, or bimodal soils, can be soil created, changes in the soil water retention curve, punodreerssitz1oeosId,nwathrsiocshdomiulsacytthbiaoet nnparteusreanllty two distinct occurring or dominant a result of particleascihziee,vAedttebrybecrgomlimpuittisnagndthceoemfpfeaccttiivoen scturrevses wcoenresidering evathlueapterodd. Uct between suction and degree of saturation (see compacRtieotna.ining structures often retain soils that are in partially section 2.1). Bacspkoroiglgrraaormeuminnevd.esTthigeateexdpethrirmouegnhtala laboratory experimental steps to characterize the soils copmerpfaocrtmedanocne tihseinwfelut esnidceedofbythethceoemnpvaircotinomnecnutarvl eactions. Water retention behaviour of the tested soil are described. Betweenreatagignreedgasotiiolns,s.asTahcisoinssethqeuecnascee,otfhtehsehpeoarrosutsrecnlgatyh of thceompleTxhseoialc, haisevwedellexapserthime efnotraclersesauclttisngaraet eamppalortyiecdle for the soil of gBeroamsialitae,riaBlraiznicl,rewasheicsh doufetentoexthhiebitisnccroelalsaepsionfg matrilcevel. Modelling of the water retention behaviour of the tested behaviosuurc.tiMona,niyndsutucdiniegsacraerdriuecdtioonutoifnthtehitshrsuosilt omnattheeriareltaining Thesomilinaenrdaltohgeincatloccoonmstpituutteiotnheofavsaoiillasblies saheparirmsatrreyngth. In thi(s1 octaheeadrtrhaltahlruumstinairuemcaonndsid1etreetdrahbeydrpaelrsfoilrimcai)nagndste2a:1dy state soil alsroegdairsdp,laytshegrecahtarmacinteerriazlaotgioicnal ovfaritahbeilitwy,atwerhicrhetentio(n1 octaanhaeldyrsaels. In thi(s1 octaheeadrtrhaltahlruumstinairuemcaonndsid1etreetdrahbeydrpaelrsfoilrimcai)nagndste2a:1dy state soil alsroegdairsdp,laytshegrecahtarmacinteerriazlaotgioicnal ovfaritahbeilitwy,atwerhicrhetentio(n1 octaanhaeldyrsaels. aRluamnkininiuem’s thaenodry2andtetCraohueldormalb’ssimliceat)hod are makes ibtedhiaffviicouulrt toof uthnedeinrsvtoalnvdedhoswoilesacphlamysinaefruanl dpalamyesnatal roles.tructureems.ploOyfedtheto meisnteimraalste 1:t1he arleateKraaloleinairtteh atnhdrust of role in tIhnedeoevde,raltlhbeehwavaitoerur roeftethnetiosonil.behaviour controls thHe alloysuintes,atuwrahtielde sothiles omnintheeralrseta2in:1ingcsotrrruecstpuornedat tdoifferent

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