Creep behaviour and permeability evolution of cataclastic sandstone in triaxial rheological tests

Abstract

This article reports the results of triaxial creep tests of cataclastic sandstone cored from the dam foundation of a hydropower station. Meanwhile, the permeability measurements are performed in course of creep tests under hydro-mechanical coupling. The creep behaviours of studied rock and their effects on the permeability evolution have been analysed in detail. The results show that the studied rock exhibits pronounced irreversible time-dependent deformations. The strain rate increases by exponential functions as the deviatoric stress increased and the confining pressure decreased. The long-term strength can be defined at which the critical point of expansion strain rate is greater than the compression strain rate. In addition, important plastic deformation, obvious dilation and large strain rate are observed in the last stage of experimental tests. The permeability change shows some mutative correlation with the material porosity during the time-dependent deformation. But the trend of change is decreasing with the increase of deviatoric stress for all specimens. During the stage of steady creep, the permeability variation slowly decreases quasilinearly. It indicates that the fluctuation has no significant effect on permeability evolution. These results may provide the basis for the establishment of hydro-mechanical coupling creep model and the long-term stability analysis of structures.

Permeability Evolution of Granite Gneiss During Triaxial Creep Tests

“…With the rapid initiation, propagation and coalescence of microcracks, a major macrocrack is ultimately formed and creep failure occurs. At this stage, the permeability increases rapidly and the rock seepage The permeability evolution in creep tests under different pore pressures shows a phase characteristic, which is similar to the results obtained by Zhang et al (2015b). Based on our previous test results for granite gneiss in triaxial compression tests (Liu et al 2016) and the results of this study, the permeability evolution is associated with microcrack development during the process of rock deformation and failure.…”

Model for (De)Compaction and Porosity Waves in Porous Rocks Under Shear Stresses

“…Some studies also report axial creep strain rates as a function of applied stresses (Brantut et al, 2013; Heap et al, 2015; Rybacki et al, 2015). The works of Zhang et al (2015), Makhnenko and Podladchikov (2018), and Sabitova et al (2019) report volumetric strain rates. Relatively few studies focus on characterizing the yield surface and viscoplastic potentials (Maranini & Brignoli, 1999; Tsai et al, 2008; Weng et al, 2010).…”

Experimental investigation of creep behavior of clastic rock in Xiangjiaba Hydropower Project

“…The experiments were performed with the rock servo-controlling rheological testing machine (Zhang et al 2014a). This equipment can be used to carry out conventional compression tests and rheological tests such as uniaxial creep tests and triaxial creep tests.…”

“…A lot of deformation failures and losses of stability in geotechnical projects are not instances of transient destruction, but develop over time (Dusseault and Fordham1993;Boukharov et al 1995;Damjanac and Fairhurst 2010). Deformation of the dam foundations and abutments can last for several decades, and creep failure of rock tunnels can occur after construction for several decades (Fan 1993;Gudmundsson et al 2010;Zhang et al 2012;Zhang et al 2014a). Therefore, it is essential to study the creep properties of rocks.…”