Abstract
Dynamic and static coupling loads (DSLs) are one of the most common stress environments in underground engineering. As the depth of a roadway increases over the life of a mine, the static load of the ground stress field increase multiplies, and the cyclic operation at the working face releases a large amount of dynamic energy. Therefore, deep roadways easily induce dynamic disasters during production. In this paper, a deep roadway numerical model was built with FLAC3D to test the deep roadway under DSLs and was simulated with 16 different support designs. The ground stability in each support condition was examined and compared in terms of the ground deformation and scope of failure. The underlying support mechanism was further analyzed with numerical modeling in view of the deformation in the surrounding rock mass induced by variations in the support parameters. The results show that shortening the bolt spacing is an effective measure to control the deformation of surrounding rock whatever DSLs or static load. Under static load, the larger the anchoring length is, the more stable the surrounding rock is. Under DSLs, end grouting length (S = 600 mm) and full grouting length (S = 1800 mm) can effectively control the deformation of surrounding rocks and enhance the stability of surrounding rocks. The results contribute to the design of supports in the field of underground coal mines and provide a basis for determining the reasonable support scheme for roadways.
Highlights
With the increase in energy demand and the increasing intensity of mining, shallow resources are decreasing, and the geological and geotechnical conditions of deep mining have become common in mines worldwide
With the expansion of deep coal mining, dynamic disasters such as mine seismicity and rock bursts caused by mining are becoming increasingly prevalent
Further analysis of the simulation results has been conducted, which contributes to the stability analysis, support design, and optimization under DSL conditions
Summary
With the increase in energy demand and the increasing intensity of mining, shallow resources are decreasing, and the geological and geotechnical conditions of deep mining have become common in mines worldwide. Cyclic operations at the working face, rock formation breakage, fault slip, and other dynamic events release shock waves that trigger the sudden release of elastic energy in the high-stress concentration zone, which induces large-area vibration of the rock formation and unstable failure. In the process of dynamic disasters, strong disturbance energy will be released, as well as complex original rock stress fields caused by deep mining. Dou et al proposed the principle and prevention of dynamic and static superimposed loads of coal mine [12] He et al conducted a numerical simulation study on rock burst induced by a hard roof [13, 14]. Ese theories reveal the mechanical response of the bolt under the DSLs in detail and explain the mechanical method of the surrounding rock deformation controlled by the bolt in the dynamic load roadway. Further analysis of the simulation results has been conducted, which contributes to the stability analysis, support design, and optimization under DSL conditions
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