Abstract

A dual-scale modeling approach is proposed to model splitting failure zone in surrounding rock of roadway. Compared with previous models, our model has three innovative points: first, closure effect of pre-existing fracture is considered; second, hyperbolic equation is utilized to describe the path of wing crack propagation which is more closed to reality. third, representative elemental volumes are adopted to tackle the damage localization. The new model is applied to investigate the influence of microcrack parameters on the depth and area of splitting failure zone. This study can be realized due to the implementation of representative elemental volumes. Results show that: with the increase of microcrack length, the depth and area of splitting failure in surrounding rock become lager; with the increase of initial angle, the depth and area of splitting failure in surrounding rock increase first and then decrease, tend to zero finally. When the initial angle is equal to 45°, the depth and area of splitting failure reach a maximum value. When the initial angle is approaching 90°, microcracks form self-locking, splitting failure is significantly inhibited; with the increase of friction coefficient, depth and area of splitting failure are gradually reduced and finally tend to 0.

1. INTRODUCTION

In China, coal demand increases rapidly due to the rapid economic development. This situation leads to exhausting of shallow coal resources, meanwhile buried depth of mines become larger. The buried depth of some coal mines are even greater than 1000m, such as Zhangxiaolou coal mine, jiahe coal mine, zhangji coal mine et.al. The openings of these coal mines are in high initial stress. During excavating the openings under high initial stress, a large range of splitting failure zones were always observed. This kind of phenomenon has been the experience [1]. Splitting failure always causes the equipment damage, project delay, economic losses. Therefore establishing the splitting failure model play a key role in stability evaluation of deep surrounding rocks and the proper supporting design for openings.

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