ABSTRACT:

BS3D is an algorithm for analyzing the stability of single rock blocks of general shapes for general failure modes of simultaneous sliding and truly large rotation under all types of forces, including non conservative forces, such as water pressures. In order to validate BS3D with regard to one of the most common failure modes, i.e. wedge failures, sixty four physical models were analyzed using BS3D and also Block Theory based on limiting equilibrium. For each of the four observed different failure modes, one case was chosen and 3D DDA analysis was conducted. The safety factors calculated using BS3D are the same as the safety factors obtained using Block Theory. The static failure modes predicted by BS3D agree well with those observed in the physical model tests. BS3D could correctly find all possible failure modes (torsional sliding and translational sliding), without resorting to any prior information or numerical artifacts, while 3D DDA and the Block Theory could not.

1. INTRODUCTION

Validation is the process of determining the degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model. Since critical decisions are made based on the results of computational means ([1-6]), validation has received increasing attention in computational mechanics. The problems entailed in a validation process are exacerbated in rock engineering, where it is very difficult, or even impossible to test a rock mass at a convenient and representative scale. Indeed, rock engineers have attacked this issue by resorting to two validation methods, namely case histories, and model tests. Failure modes of a rock block subject to gravity includes translation, rotation about an edge, rotation about a corner, torsional sliding, and slumping. Making use of limiting equilibrium methods, John [7], Londe et al. [8], Hendron et al. [9], Hoek and Bray [10], Warburton [11], Priest [12], and Goodman and Shi [13] considered wedge sliding only. Pioneered by Wittke [14, 15], the study of rotational failure modes was also pursued using analytical methods by Chan and Einstein [16], Mauldon and Goodman [17] and Tonon [18]. These analytical methods cannot handle general simultaneous sliding and rotation; Yeung and co-workers [19-21], thus used a numerical method, such as the Discontinuous Deformation Analysis (DDA), to overcome the problem. However, there seems to be no approach that can handle general modes of simultaneous sliding and truly large rotation under general forces, including non conservative forces, such as water forces. BS3D [22] is an algorithm for analyzing the stability of single rock blocks of general shapes for general failure modes of simultaneous sliding and truly large rotation under all types of forces, including non conservative forces, such as water pressures. In this paper, the results of physical model tests reported by Yeung et al. [19] are used, in order to validate BS3D, with regard to one of the most common failure modes, i.e. wedge failures.

2. PHYSICAL MODELS

Physical models were constructed and tested by Yeung et al. [19] in order to validate Block Theory and 3DDDA as wedge stability analysis methods.

This content is only available via PDF.
You can access this article if you purchase or spend a download.