Predicting the volumetric variation due to changes in suction, applied stress and swelling pressure

Roberto Galaviz-González,María De La Luz Pérez-Rea,Jaime Robles-Sotelo,Eduardo Rojas,Jaime Horta,P Delage,Y.-J Cui,S Ghabezloo,J.-M Pereira,A.-M Tang

doi:10.1051/e3sconf/20160914022

Roberto Galaviz-González, María De La Luz Pérez-Rea + Show 8 more

Open Access

https://doi.org/10.1051/e3sconf/20160914022

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Abstract

The settlements produced by the load transmitted to the structure on expansive soils, and those calculated by the classical theories of soil mechanics, are different because the swelling pressure acts inversely to the applied stress. In this paper we describe a procedure to determine a volumetric variation coefficient by hydration (αh ) which considers the expansive soil behaviour. In order to do this, it is necessary to know the soil’s initial water content, the swelling pressure, and the applied stress. Soil suction and swelling pressure were measured with filter paper technique and a mechanical oedometer, respectively. Unsaturated undisturbed samples of expansive soil were used. The water content was varied, starting from 0%, with increments of 5.5% to reach 38%. Furthermore, we present a set of curves that show the magnitude of the coefficient (αh ) associated to a water content, and the relationship between applied stress and swelling pressure. The results show that the variation of the coefficient under different initial water contents ranges between 0% to 22%. This is because water is strongly attracted by clay minerals, but this attraction decreases as water layers are father from the surface of clay minerals, thus decreasing its swelling potential.

Highlights

Lightweight buildings such as houses, can be damaged if they are built over expansive soils [1]
This paper presents the determination of a coefficient associated to an initial water content and the relationship between the applied stress and swelling pressure measured on conventional laboratory equipment, which can be introduced into soilstructure interaction methods (SSI) in order to facilitate the prediction of soil settlement
The relationship between swelling pressure σswe and volumetric strain ε can be inferred from Figure 3

Summary

Introduction

Lightweight buildings such as houses, can be damaged if they are built over expansive soils [1] This is because water content variations induce volume strains on soils. This has led to overestimations and to expensive foundations. Some methods predict volumetric strains and optimize the design of foundations These methods were proposed by Zeevaert [2], Nelson and Miller [3], Lytton [4], and ASTM D4546 [5]. Light structures built on these soils usually contain structural damages as a result of the volumetric strains of the soils [1, 9]. When their water content increase, expansive soils swell affecting the structure stability [10]

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