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.