Abstract
Rockburst of deep roadway was induced by the superposition of mine earthquake disturbance and high static stress exceeding the limit strength of coal-rock mass. To study the roadway impact instability characteristics caused by mine earthquake disturbance and to propose an optimized support scheme, the discrete element model of the roadway structure was established based on the 1305 working face of the Zhaolou Coal Mine. The influence of mine earthquake amplitude and hypocenter location on the roadway was analyzed. The mesocrack evolution characteristics of the roadway were simulated and reproduced. Characteristics of stress field, crack field, displacement field, and energy field of the disturbed roadway with different support schemes were studied. The results showed that the greater the amplitude of the mine earthquake was, the severer the roadway impact failure was. The upper and left hypocenters had a significant influence on the roadway. The superposition of the high static stress and the dynamic stress due to the far-field mine earthquake resulted in the impact instability of coal-rock mass around the roadway, causing severe roof subsidence as well as rib and bottom heave. The evolution of tensile cracks caused the severe impact failure of roadway from a mesoscopic perspective. Using the flexible support to reinforce the roadway retarded the stress decline in roof and rib, improved the self-stability, reduced the number of near-field cracks, and decreased the displacement. Meanwhile, it allowed the roof and rib deformation, which was conducive to releasing elastic energy in surrounding rocks and reducing mine earthquake energy. The cracks and deformation in the floor were controlled by using the floor bolt. The optimal support scheme for a roadway to resist mine earthquake disturbance was proposed: “bolt-cable-mesh-steel strip-π-beam + floor bolt.” The research results have a specific guiding significance for the support of the coal mine roadway.
Highlights
With the increasing depth and strength of coal mining, a growing number of rockburst mines appear. e frequency and intensity of rockburst were aggrandized year by year [1,2,3]
It is found that the scheme could effectively control the initiation and expansion of floor cracks, transfer the stress concentration phenomenon from the superficial layer to the deep layer of the surrounding rock, and improve the integrality and stability of the roadway. e support scheme “bolt-cable-mesh-steel strip-π-beam + floor bolt” proposed in this paper had a great effect on preventing roadway impact instability caused by mine earthquake disturbance
Based on the background of the 1305 working face in the Zhaolou Coal Mine, this paper studied the characteristics of roadway impact instability induced by mine earthquake disturbance from the aspects of stress field, crack field, displacement field, and energy field. e corresponding optimal support scheme was proposed
Summary
With the increasing depth and strength of coal mining, a growing number of rockburst mines appear. e frequency and intensity of rockburst were aggrandized year by year [1,2,3]. Jing et al [23] and Xiao et al [24] proposed the support principle to strengthen the integrity and loading capacity of the surrounding rock and control roadway impact instability. Another frequently used technique is the mesh support. From Peter and Cai’s view [30], support in rockburst-prone areas must be able to absorb dynamic energy and adapt to sizeable sudden rock deformation due to rockburst and related expansion Under his influence, Yang et al [31] proposed that the activeflexible support can increase the confining pressure of surrounding rock to suppress the tensile stress state of surrounding rock. The influence of the mine earthquake on roadway support has been neglected, causing the waste of supporting materials and the nonideal control effect of roadway impact instability. is paper aims to study the characteristics of roadway impact instability induced by mine earthquake disturbance and propose an optimized support scheme
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