厚松散层薄基岩开采覆岩离层裂隙演变与下沉分形特征研究

Study on Evolution and Subsidence Fractal Characteristics of Overlying Strata in Thick Loose Layers and Thin Bedrocks

为研究厚松散层薄基岩开采下覆岩离层裂隙的演变和下沉规律,结合山东郭屯煤矿1302首采工作面地质条件,采用相似材料模拟试验和分形相结合的方法,对开采过程中覆岩裂隙网络和下沉的分形特征进行研究。研究结果表明:覆岩裂隙的演变特征具有较好的自相似性和分形特征;随着工作面的推进,覆岩裂隙网络的分形维数呈开采前期和中期跳跃式剧增,后期缓慢平稳增加的走势;开采全过程出现四处离层,其出现位置和大小均呈现出一定的规律性;在厚松散层荷载作用下,薄基岩层仍能形成稳定的强承载结构;采空区覆岩的沉降量与裂隙网络的分形维数呈现出近似双折线的非线性关系。

In order to study the evolution and subsidence law of the overlying rock separation fracture under the mining of thick loose bed and thin bedrock,combined with the geological conditions of 1302 face of the first mining face of Shandong Guotun Coal Mine,the fractal characteristics of the overlying rock fracture network and subsidence in the mining process are studied by using the method of similar material simulation test and fractal.The research results show that:the evolution characteristics of overburden fractures have good self-similarity and fractal characteristics;as the working face advances,the fractal dimension of the overburden fracture network increases slowly and steadily during the early and mid-jumping periods.There are four layers in the whole mining process,and the location and size of the layers show a certain regularity;under the action of thick loose layer,the thin bedrock layer can still form a stable and strong bearing structure;the settlement of overburden in goaf and fractal dimension of fracture network show a nonlinear relation of approximately bifold line.