Abstract
To effectively control the large surrounding rock deformation of the mining roadway under multiple excavations and mining in Wangcun coal mine, the field investigation, numerical simulation, field test, and monitoring were conducted, and the characteristics of stress and deformation evolution of the surrounding rock under the influence of multiple excavations and mining were analyzed; then the collaborative supporting technology of high prestressed bolt and short anchor cables was proposed in this study. The results show the following: (1) under the influence of multiple excavations and mining, the peak vertical stress of the typical air-return roadway reaches 23 MPa, and the deformation increases by about 2.8 times after the mining of adjacent panel. (2) The principle of the roadway support under the influence of multiple excavations and mining in Wangcun coal mine is determined; from the perspective of prestress, we can conclude that the active support of short anchor cables is better than that of long anchor cables. (3) Based on the results of the field monitoring, the bolt stress can be divided into four stages: the loss stage of prestress, the sudden-decrease stage of the roof periodic weighting, the decrease stage of advanced support, and the rapid-increase stage of strong disturbance. Due to the large anchorage range of anchor cables, there is no decrease stage of advanced support. After the application of prestress, the bolt stress of side bolts and top bolts decreases, and the reduction amplitude is up to 30 kN. (4) As the panel advances, the deformation of the surrounding roadway increases, and the growth rate is also increasing gradually. However, the final displacement of the roof, floor, and two sides is within 18 mm. The bolt and anchor cables are not broken, and the control effect is good. The research results have a certain reference value for similar roadway control.
Highlights
(3) Based on the results of the field monitoring, the bolt stress can be divided into four stages: the loss stage of prestress, the sudden-decrease stage of the roof periodic weighting, the decrease stage of advanced support, and the rapid-increase stage of strong disturbance
Due to the large anchorage range of anchor cables, there is no decrease stage of advanced support
Huang et al [8] investigated the large deformation characteristics of the roadway with soft coal seams in the deep strong mining and proposed theoretical framework of the rheology of the surrounding rock and large deformation of the roadway caused by structural instability in the deep strong mining [9]
Summary
E overall vertical stress of the surrounding rock increases significantly, and the peak vertical stress of the coal pillar stress is 43.9 MPa, while that of air-return roadway 5103 is 23 MPa It shows that the mining of panel 8101 has a great influence on the dynamic pressure of airreturn roadway 5103 at this time. At this time, the maximum roof subsidence of the roadway is greatly increased, which increases by 194.5% during the original excavation period. The maximum roof subsidence of the roadway is greatly increased, which increases by 194.5% during the original excavation period It shows that the mining of adjacent panel 8101 leads to the significant influence of dynamic pressure, resulting in serious deformation of air-return roadway 5103. The comprehensive support effect is better when the length of anchor cables is in the range of 4 m–6 m
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