Coal Engineering ›› 2022, Vol. 54 ›› Issue (3): 105-111.doi: 10.11799/ce202203020

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Study on fault barrier effect on overburden deformation and stress transfer based on stress wave theory

  

  • Received:2021-09-07 Revised:2021-11-08 Online:2022-03-15 Published:2022-05-13

Abstract: Surface subsidence laws under the influence of fault is significantly different from that under common geological conditions. In order to study mining subsidence mechanism influenced by fault, the disturbance of working face mining on overlying rock is regarded as the transfer of stress wave in rock stratum medium. At the same time, the stress expressions of wave transferring from weak rock to hard as well as from hard rock stratum to weak are established. Stress wave transmission influenced by weak strata medium is ana-lyzed by theory and numerical calculation to reveal the mechanism of fault barrier to overburden movement and stress transfer. At last, it’s verified by similar model experiment and the influence of different fault characteristic parameters on the barrier is analyzed by numerical calculation. The study has showed that firstly, the disturbance of mining on overlying rock is closely related to the stress wave velocity generated by mining, and the greater the stress wave velocity is, the greater the disturbance of mining on overlying rock is. Secondly, fault rock mass being as fractured zone, stress wave velocity decreased significantly after through the fault zone under the action of multiple reflection effect. The ratio of maximum stress wave velocity according to mining wall and the other side is 4.68 ~ 35.61. Fault has an obvious blocking effect on the transfer of mining-induced stress wave, that is, the fault has a blocking effect on the transfer of min-ing-induced stress, and the overburden movement and deformation mainly occur in the mining wall. Lastly, for the reason that the stress wave velocity attenuation in shallow fault zone is less than that in deep fault zone, the rock mass in shallow fault zone has discontinuous deformation before the rock mass in deep fault zone. The order of transmission and barrier effect of fault characteristic parameters on overburden movement and deformation is fault zone width > fault drop > fault dip Angle > friction angle > cohesion. The results are of practical significance to the analysis of surface subsidence laws influenced by fault and the protection of surface structures at outcrops.

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