A numerical study of flexural buckling of foliated rock slopes

Abstract

SUMMARYThe occurrence of foliated rock masses is common in mining environment. Methods employing continuum approximation in describing the deformation of such rock masses possess a clear advantage over methods where each rock layer and each inter-layer interface (joint) is explicitly modelled. In devising such a continuum model it is imperative that moment (couple) stresses and internal rotations associated with the bending of the rock layers be properly incorporated in the model formulation. Such an approach will lead to a Cosserat-type theory. In the present model, the behaviour of the intact rock layer is assumed to be linearly elastic and the joints are assumed to be elastic}perfectly plastic. Condition of slip at the interfaces are determined by a Mohr}Coulomb criterion with tension cut o! at zero normal stress. The theory is valid for large deformations. The model is incorporated into the "nite element program AFENA and validated against an analytical solution of elementary buckling problems of a layered medium under gravity loading. A design chart suitable for assessing the stability of slopes in foliated rock masses against #exural buckling failure has been developed. The design chart is easy to use and provides a quick estimate of critical loading factors for slopes in foliated rock masses. It is shown that the model based on Euler's buckling theory as proposed by Cavers (Rock Mechanics and Rock Engineering 1981; 14:87}104) substantially overestimates the critical heights for a vertical slope and underestimates the same for sub-vertical slopes.

An analytical solution to slip buckling slope failure triggered by earthquake

“…However, the effect of earthquake on such failure mode has not been well understood by previous researches i.e. Cavers (1981), Sun (1988), Pant and Adhikary (1999), and Adhikary et al (2001). In this paper, an analytical solution on slip buckling slope failure is presented by considering the effect of earthquake as well as the pore water pressure.…”

“…Sun (1988) treated the buckling of rock slabs as a beam stability problem using the elastic theory, and suggested an energy equilibrium principle for solving this problem. Pant and Adhikary (1999), and Adhikary et al (2001) investigated the mechanism of flexural buckling failure of foliated rock slopes, using both explicit and implicit finite element numerical models in AFENA code (a large deformation Cosserat continuum model). Qin et al (2001) presented a catastrophe cusp model to study the failure mechanisms of the slip-buckling slope, and suggested the important role of the historical evolutionary process of slope on its failure.…”

Numerical Simulation of Bed Separation Development and Grout Injecting into Separations

“…Adhikary and Dyskin (1997) successfully extended the application of the Cosserat theory into stratified rocks. The model was further developed to allow elastic-plastic slip occurring with no tension at the joints and large deformation analyses (Adhikary et al 1999(Adhikary et al , 2001). The developed model was incorporated into the finite element program COSFLOW (Chen et al 2002a, b;Guo et al 2003) and has been successfully applied to mining subsidence and water/gas flow analyses in layered rock (Guo 2004;Chen 2006).…”

A Comprehensive Study on Subsidence Control Using COSFLOW

“…COSFLOW incorporates the layered Cosserat continuum formulation, which provides major benefits over conventional continuum numerical models of sedimentary rock in that the code is able to efficiently simulate rock breakage and slip as well as separation along bedding planes (Cosserat and Cosserat 1909;Adhikary et al 1999Adhikary et al , 2001. In addition, COSFLOW couples fluid flow with strata deformation and stress, and can be used to simulate the effects of mining on ground water systems and predict gas emission during longwall mining (Chen 2006).…”