Modeling of elastoplastic damage behavior of a claystone

Deformation in cemented mudrock (Callovo–Oxfordian Clay) by microcracking, granular flow and phyllosilicate plasticity: insights from triaxial deformation, broad ion beam polishing and scanning electron microscopy

“…Chiarelli et al (2000) showed that COX is more brittle with increasing calcite content and more ductile with increasing clay content, and they proposed two deformation mechanisms: plasticity induced by slip of clay sheets and induced anisotropic damage as indicated by microcracks at the interface between grains and matrix; however, they provided little microstructural evidence to support this. Gasc-Barbier et al (2004), Fabre and Pellet (2006), Chiarelli et al (2003) and Fouché et al (2004) reported that the COX has an unconfined compressive strength of 20 to 30 MPa and a Young's modulus of 2 to 5 GPa. In the context of underground storage of radioactive waste, these papers try to predict the mechanical evolution of COX over the period of thousands of years.…”

Modeling of inherent anisotropic behavior of partially saturated clayey rocks

“…A comprehensive experimental program has been carried out on argillite (including Tournemire argillite and Meuse/HauteMarne argillite) at the Lille Laboratory of Mechanics, and the results have been reported by Niandou et al [23], Chiarelli et al [4] and Zhang et al [10]. A short summary of test data on argillite is given in this section, and these data will be used in Section 4 to validate the numerical predictions.…”

“…Due to the presence of clay elements such as smectite, the mechanical behavior of argillites is very sensitive to the saturation degree. A number of experimental investigations [1][2][3][4][5][6][7][8][9][10] have been performed on various clayey rocks in partially saturated conditions. Certain constitutive models have been proposed using the concept of effective stresses on the partially saturated field.…”

Stress/Strain-Dependent Properties of Hydraulic Conductivity for Fractured Rocks

“…Although a modified Drucker-Prager yield function may be more suitable for this formulation in order to model plastic deformation properties of intact rock such as pressure dependency, strain hardening, transition from compressibility to dilatancy and stress path dependency (Chiarelli et al, 2003), the criterion given above may keep the formulation compact and does not lose generality. Other yield functions, such as the modified Drucker-Prager criterion (Chiarelli et al, 2003) or the modified Hoek-Brown criterion (Hoek et al, 1992), can also be integrated into the formulation without major mathematical difficulties. With the researches conducted by Yuan & Harrison (2004) and Alejano & Alonso (2005), the decaying process of the rock dilatancy angle in line with plasticity can be described by the following negative exponential expression through the equivalent plastic strain of rock matrix, p R ε (Lai, 2002):…”