Experimental study of the hydro-mechanical behaviour of unsaturated argillaceous rocks

Jairo Martin Espitia,Bernardo Caicedo,Luis Vallejo,P Delage,J.-M Pereira,S Ghabezloo,A.-M Tang,Y.-J Cui

doi:10.1051/e3sconf/20160914007

Abstract

The aim of this paper is to study the influence of total suction on some physical/mechanical properties related to argillaceous rocks from the Colombian Andes. A wetting path was applied to the rocks using the vapor transfer technique with continuous recording of mass and deformations. Uniaxial compression tests were conducted on specimens at different levels of suction. In addition, microstructural observations are carried out using a Mercury Intrusion Porosimeter Apparatus. Results from the laboratory tests indicate that anisotropic deformations took place during the wetting path. Also, total suction contributed to a considerable and non-linear reduction in the compressional wave velocity, peak compressive stress, and elastic modulus of the tested samples. Microstructural analysis indicated the influence of the size and number of the pores in the samples on their high levels of suction.

Highlights

A substantial portion of rocks forming part of the earth’s crust are argillaceous nature and are usually present in many mining and infrastructure projects[1]
Some features of the behavior of this material in unsaturated conditions can be highlighted as follows: (I) during the application of hydric cycles it is observed hysteresis in the water retention curve, anisotropic deformations and permanent volumetric strains in the material; (II) elastic properties and strength are controlled by the hydric state and the hydric history of the material; (III) the material is degraded as a consequence of hydric cycles
The purpose of the experimental tests was to obtain a better understanding of the hydromechanical behaviour of some argillaceous rocks from the Colombian Andes mountains

Summary

Introduction

A substantial portion of rocks forming part of the earth’s crust are argillaceous nature and are usually present in many mining and infrastructure projects[1]. In Colombia a significant part of the population, infrastructure and mining projects are located in the eastern Andes mountain range. In this area, some argillaceous rocks outcrop causing significant challenges for the stability of rock excavations. Some features of the behavior of this material in unsaturated conditions can be highlighted as follows: (I) during the application of hydric cycles (without mechanical loading) it is observed hysteresis in the water retention curve, anisotropic deformations and permanent volumetric strains in the material; (II) elastic properties and strength are controlled by the hydric state and the hydric history of the material; (III) the material is degraded as a consequence of hydric cycles

Objectives

Methods

Results

Conclusion