Creep response in shear of clayey geo-materials under saturated and unsaturated conditions

Abstract

Abstract. Translational slides in clays are often characterized by long-lasting intermittent movements associated with the fluctuations of pore-water pressure. Physically-based models designed to support hazard analysis of landslide movements and early warning systems require the integration of time-dependent (viscous) constitutive models for the shear displacements because landslide movements are typically controlled by the viscous behaviour of the clay geomaterial. This paper presents an investigation of the viscous response of a clay geo-material under saturated and unsaturated conditions. Creep and relaxation tests have been first carried out on saturated clay samples by means of direct shear box. To gain a conceptual understanding of the viscous response of the clay in shear, mechanical analogues were considered based on combinations of springs and dashpots. Preliminary tests on unsaturated samples were finally carried out to gain a first insight into the viscous response of the clay under unsaturated conditions.

Rate Dependency and Stress Relaxation of Unsaturated Clays

“…Submitted Nov 2018; Published Oct 2019. https://doi.org/10.1061/(ASCE) GM.1943-5622.0001507. magnitude of reconstituted clays from the sliding zone soils of the Qianjiangping landslide in triaxial conditions and reported a decrease in creep strains with an increase in soil suction. Nazer and Tarantino (2016) investigated the viscous response (in both creep and relaxation modes) during shearing of reconstituted Ball clay using shear box and developed an analogue model for simultaneous modelling of creep and relaxation. Wang et al (2017) performed a set of triaxial stress-relaxation tests on unsaturated lime-treated expansive clays of Hefei Xianqiao Airport site in China, at suctions of 50 and 100 kPa, and studied the effects of pre-relaxation strain level, pre-relaxation strain-rate, and relaxation time.…”

Swelling pressure of a sodium bentonite in solutions of different suction

“…Lai et al (2014) [4] measured volume change using unsaturated triaxial compression apparatus, which controlling matric suction cause deformation, and was possible to predict the slope stability. As similar unsaturated soil researches, Nazer and Tarantino (2016) [5] conducted out unsaturated soil creep test in order to investigate deformation behaviour associated with suction considering. The coverage literature is effectively to solve the hydration-mechanical properties for bentonite material.…”

Creep Characteristics of Soil in the Sliding Zone of Huangtupo Landslide

“…Tang et al conducted an in situ triaxial test, believing that the sliding zone soil of the Huangtupo landslide was part of a creep process, and derived a constitutive equation with linear and nonlinear viscoplastic terms to fit the creep process of the sliding zone soil [2]. At present, the direct shear creep test of sliding zone soil is mostly focused on the creep damage stage but not on the attenuation creep stage of sliding zone soil [12,13]. Through direct shear tests, Zhu et al found that the red-bed sliding zone soil was in the accelerated creep stage and proposed the long-term strength of the sliding zone soil [14].…”