To evaluate the surrounding rock stability in steeply dipping seams, based on the detection technology of soundwave and electromagnetic wave, the quality of surrounding rock and separation area location for roadway are identified. The degree of fracture for the inner wall of holes is detected and analyzed using the optical borehole imaging device, which proves the accuracy of the formers' detection. The results show that: crack distribution zone and loose circle appears alternately, the surrounding rock stability within the crack distribution zone and loose circle is generally poor, the coal rock broken interface is clear and has obvious zonal distribution characteristics, the fracture of roof and two sides in roadway mostly present the evolution characteristics of irregular zonal, fracture zone and intact zone appear alternately, the distribution area of surrounding rock fracture in coal mass side is larger than the rock side.

1 Introduction

Xinjiang Wulumuqi mining area is an enrichment region of steeply dipping coal seams, over 30 layers of different thickness and space coal seams (dipping of 45° ~ 87°) are located there. With the mining period and yield increase, the current largest mining depth has reached 400 m, steeply dipping coal seams' storage structure and the "multilayered empty space" caused by the horizontal section top-coal caving, plus water in goaf, toxic and harmful gas accumulation, have formed the overlying coal and rock mass environment with a complex structure above deepworking face. Under this condition, the deformation characteristics of roadway in this environment are different from that in shallow mine (Qian, Q.H. 2004, He, M.C. 2005, Xie, H.P. 2002, He, M.C. et al. 2005) too.

Real time assessment of surrounding rock stability is one of important means for ensuring the safety of mining. After the effect of secondary stress and mining influence relaxation induced by excavating roadway, surrounding rock will crush and cave with the characteristics of partition distribution. Loosen zone of surrounding rock is a dynamic process of occurrence, development and stable, stable loose circle size is the result of the structure of surrounding rock, stress, coal and rock strength, excavation disturbance and other factors. Therefore, the loose circle caused by excavating is classified by Dong, F.T. et al (1994) according to the depth of surrounding rock fragmentation, which forms the supporting theory basis of loosen zone. The surrounding rock loose zone of deep roadway is preclassified for guiding practice by Jing, H.W. et al (1996) on the basis of shallow loose zone. However, because of the special structure of steeply dipping coal seam with repeatedly mining disturbance, the loose zone of roadway surrounding rock is in process of dynamic development, loose broken belt transfers continuously to the deep-seated of coal and rock mass so that traditional surrounding rock classification method for loosen zone isn't applicable to the present situation.

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