Modelling and calibration for cyclic soil-structure interface behaviour

Borana Kullolli,Hans Henning Stutz,Matthias Baeßler,Pablo Cuéllar,A Tarantino,E Ibraim

doi:10.1051/e3sconf/20199213007

Abstract

The structural performance of many geotechnical systems (e.g. axially-loaded pile foundations), depends on the shearing resistance at the soil interface, which may govern the load bearing capacity of the foundation. Experimental investigations have shown that this interaction is mainly localised within a narrow shear band next to the structure. Under cyclic loading, a contraction of the soil at the interface may arise (net volume loss), possibly leading to a stress relaxation and thus to a reduction of the load bearing capacity (the so-called friction fatigue). Based on the constitutive similarities between soil continua and interfaces, we propose here the adaption of a Generalized Plasticity model for sandy soils for the numerical analysis of interface problems. In this contribution, the results of an experimental campaign for the parameter calibration of the constitutive model are presented. The tests have been conducted with a ring shear device involving different normal stresses, roughness of the steel plates as well as cyclic loading. The new modelling approach shows promising results and has the additional practical advantage that the interface zone and the soil continuum can both be described with the same constitutive model in general boundary value problems.

Highlights

Interface behaviour involves complex phenomena, which are related to different factors such as roughness of the contact body [1], normal stress at the interface [2, 3], soil density [4] and soil grading [5]
Once the sample is mounted into the ring, a vertical cylinder is applied at the top of it to exert the normal stress
The roughness effect and normal stress variation can be calibrated through modification of Mf and β0 as in table 2 and 3

Summary

Introduction

Interface behaviour involves complex phenomena, which are related to different factors such as roughness of the contact body [1], normal stress at the interface [2, 3], soil density [4] and soil grading [5]. Among the above mentioned influences, the roughness of the foundation has a major influence for the interface shear behaviour [7]. Experimental observations for dense sand against rough surfaces have typically shown general behaviours like contraction, dilatancy, hardening, and softening [3] under. The shear behaviour of rough interfaces is further characterised by an asymptotic state at large shearing displacement. For smooth interfaces in a dense sand state it can be observed that the shear stress increases sharply at the beginning of the shear test, it decreases slightly before reaching the residual state, while for loose sands the behaviour is overall contractive [8]. It is important to note that with rough structural interfaces, the shear failure takes place in the soil while for smooth surfaces failure occurs close to the structural interface

Methods

Results

Conclusion