多煤层开采覆岩破断过程的模型试验与数值模拟

首先分析了研究区煤矿山西组煤层剖面和水文地质特征,针对多煤层联合开采的特点和覆岩的工程地质特征,采用工程地质力学模型实验、数值模拟计算相结合的综合研究方法,分析了多煤层开采的采动影响及岩层动态断裂机理,得出了有关岩层移动参数和多层煤同采时应力分布状态,计算得到了多煤层开采垮落带与导水裂隙带的发育高度分别为32m和81.5m,导水裂隙带高度影响范围已经达到风化带,未形成切冒,局部穿透粘土层。

MODEL TEST AND NUMERICAL SIMULATION OF OVERBURDEN FAILURE PROCESS IN MULTI-COAL SEAM MINING

Firstly, the Shanxi formation coal seam sections and hydrogeological features were analysed. Based on characteristic of the associated mining of multi-coal seams and the engineering geological characteristics of overburden, the mining impact pattern of multi-coal seam mining and the dynamic fracture mechanism of overburden were characterized. A comprehensive research method combining engineering geological mechanical model test and finite element numerical simulation was applied. The related strata movement parameters, stress distribution and influence area of multi-coal seam mining were obtained as follows: strike boundary angle=62, full extraction coefficient=0.95, the greatest subsidence angle=82, horizontal movement factor=0.39, and deviation of inflection point /mining deep=0.12. The stress distribution of multi-coal seam mining was analysed. The stress concentrated locations at the roof, bottom and surround rocks were determined. The maximum stress concentrations were on the coal wall lines. The bottom stresses tended to transfer into the coal pillar. The development height of caving zone and water flowing fractured zone of multi-coal seam mining were calculated. They were 32 m and 81.5m respectively. The assess of influence degree of coal layer safety mining was that, for the area of influence of height of crack belt reached to the belt of weathering, which didn't form the transfixion, and it penetrated the clay layer partially, there existed the possibility of sand boil when stoping. Some measures for mine water prevention and control should be used. The method of small work face, mining separate layers, mining thickness below the local strictly limit should be adopted. The results were confirmed with the field tests and assured that no geologic hazard would occur.