Abstract
Large deformation control of deep soft rock roadways has been a major problem in mining activities worldwide. This paper considers the supporting problem related to large deformation of a deep soft rock roadway in Chao’hua coal mine. The discrete element simulation method (UDEC software) is adopted to simulate a tailgate of panel 31041 in Chao’hua coal mine. The failure patterns of unsupported and primary supported roadway are simulated, and these reveal the characteristics of deformation, stress and crack propagation. The excavation of roadway leads to high deviator stress, which exceeds the peak strength of shallow surrounding rock and causes it to enter the post-failure stage. Tensile failures then initiate and develop around the roadway, which causes the fragmentation, dilation and separation of shallow surrounding rock. The compressive capacity of the primary support system is low, which results in serious contraction in the full section of the roadway. An improved control scheme is put forward for the support of a tailgate. The underground test results confirm that the improved support system effectively controlled large deformation of the surrounding rocks, which can provide references for support in the design of roadways excavated in deep soft stratum.
Highlights
The rapid development of the world economy and society causes huge resource consumption, which dries up the shallow mineral resources and causes the mining for resources to progress continuously more deeply into the earth [1]
The support theory and technical system formed in shallow mining engineering has been partially or seriously invalid in deep mining engineering [1]
The related support problems cannot be solved by the existing support theories and control measures, but must be solved by seeking stability control theory and technology that conform with large deformation failure characteristics
Summary
The rapid development of the world economy and society causes huge resource consumption, which dries up the shallow mineral resources and causes the mining for resources to progress continuously more deeply into the earth [1]. The deep soft surrounding rock mass usually has a low uniaxial compressive strength between 0.5 and 25 MPa and suffers from high in-situ stress These characters result in large rheological deformation in all directions of the roadway cross section [9]. Field applications have indicated that a single or simple support method was too weak to resist the large rheological convergence in deep soft surrounding rock [8]. As the tailgate was excavated, support materials were immediately installed, but significant surrounding rock deformation occurred several meters behind the advancing face and the excavation of the roadway was postponed To solve this problem, this paper presents a case study on failure mechanism and support techniques of deep soft rock roadway. A numerical simulation with UDEC is undertaken to reveal the stress, deformation, cracking and dilation states of soft surrounding rock, and an improved “bolt-cable-mesh + shell” support pattern is presented and evaluated to support the soft rock roadway
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