深厚表土下沿空巷道静载型失稳机制与卸−固协同控制

Static load instability mechanism and unloading and support collaborative control of gob side entry driving under deep topsoil

  • 摘要: 针对鲁西南矿区深厚表土下深部沿空巷道灾变失稳问题,以郭屯煤矿2309工作面轨道巷为工程背景,采用现场调研、理论分析、数值模拟及现场试验相结合的方法,研究深厚表土下覆岩运移演化与高静载产生机制,揭示了超高静载作用下深部沿空巷道静载型失稳定义、孕育发生过程与能量机制,基于能量分区调控原理,形成了集高强让压支护、变径封孔卸压、单元被动支护的卸−固协同控制体系。主要结论如下:不同于常规地层结构,深厚表土下覆岩运移将形成即时加载带(ILZ)和静载带(SLZ)的两带结构,煤炭开采将诱发表土层大范围运移,致使覆岩静载直接传递作用到浅部煤体上,深部巷道呈现采动应力峰值应力大、影响范围集中的特征;受表土层大范围运移导致的超高静载应力影响,巷道弹性区煤体积聚较高能量,同时浅部塑性范围减小而破碎区范围增大,致使巷道呈现出煤体持续收敛、浅部大范围破碎、锚杆内嵌失效等静载型矿压显现特征。深部巷道静载型失稳是巷道近场不同区域煤岩在深厚表土运移诱发的超高静载作用下劣化发展与能量演变的动态过程,当弹性区积聚能量E'T大于塑性区可吸收能量U'S与支护结构可吸收能量U'P之和时,将发生静载型冲击失稳。基于深厚表土下沿空巷道静载型失稳能量机制,提出了能量分区调控的“卸−固”协同调控原理,形成了集高强锚杆索让压支护、变径封孔卸压、单元被动支护于一体的围岩控制体系。现场实施应用后巷道控制效果良好,对于类似巷道支护具有参考借鉴意义。

     

    Abstract: Aiming at the problem of deep goaf roadway disaster and instability under deep overburden in the deep surface soil of the southern Shandong mining area, taking the track entry of the 2309 working face in Guotun Coal Mine as the engineering background, the research adopts the method of combining field investigation, theoretical analysis, numerical simulation and field test to study the movement and evolution of overlying strata and the generation mechanism of high static load under deep surface soil. It reveals the definition, incubation and occurrence process and energy mechanism of static load type instability of deep goaf roadways under ultra-high static load. Based on the principle of energy zoning control, a unloading and solidification coordinated control system integrating high-strength yielding support, variable diameter sealing hole unloading and unit passive support is formed. The main conclusions are as follows: unlike the conventional strata structure, the movement of overlying strata under deep overburden soil will form a two-zone structure of immediate loading zone (ILZ) and static loading zone (SLZ). Coal mining will induce large-scale movement of the overburden soil, causing the static load of overlying strata to be directly transmitted to the shallow coal seam. Deep roadways exhibit the characteristics of high peak stress and concentrated influence range under mining-induced stress. Affected by the ultra-high static load stress caused by the large-scale movement of the overburden soil, the coal in the elastic zone of the roadway accumulates high energy, while the shallow plastic zone shrinks and the broken zone expands, resulting in the static load type of mine pressure manifestation characteristics such as continuous convergence of coal, large-scale fragmentation in the shallow area, and failure of embedded anchor bolts. Static load instability of deep roadway is a dynamic process of deterioration development and energy evolution of coal and rock in different areas near the roadway under ultra-high static load induced by deep topsoil migration. When the accumulated energy E'T in elastic zone is greater than the sum of the absorbable energy U'S in plastic zone and the absorbable energy U'P in support structure, static load impact instability will occur. Based on the energy mechanism of static load type instability of roadways under deep overburden soil, the principle of unloading and support collaborative control with energy zoning regulation was proposed, and a surrounding rock control system integrating high-strength anchor bolts and cables yielding support, variable diameter hole unloading, and unit passive support was formed. After on-site implementation and application, the control effect of the roadway was good, which has reference significance for similar roadway support.

     

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