软弱薄基岩裂隙发育特征及抑突(溃)机理

Fracture Development Characteristics of Weak-thin Bedrock and the Inhibition Mechanism of Water and Sand Inrushing

为探究西部地区软弱薄基岩覆盖下的厚煤层在开采时覆岩破坏的裂隙发育规律,以及该区在开采后突水溃沙的规律、机理等,在分析软弱薄基岩厚煤层开采覆岩裂隙发育规律的基础上,结合实际生产经验,对伊犁煤田突水溃沙抑制机理进行了研究。结果表明:工作面推采方向超前80~85m出现弧形地面张性斑裂,主斑裂纹与次斑裂纹的间距分别为10m和2m左右;导水裂隙带在软弱薄基岩下厚煤层开采时发育高度变化差异较小;伊犁煤田开采时涌水量小于30m^3/h,突水溃沙情况受到了抑制,主要由于顶板岩性软弱,无法形成较大的岩块、空隙、空洞,随采随冒且采动裂隙被迅速压实、上覆地层含水层十分松散,裂隙进入之后不能再继续发展、在低水压时涌出物填充裂隙等原因。该研究成果对西部软弱薄基岩厚煤层开采顶板水害防治,以及地表生态环境保护具有意义。

In order to explore the fracture development law of overlying rock failure in the mining of thick coal seam under the cover of weak and thin bedrock in the western region of China,as well as the regularity and mechanism of water and sand bursting after mining,based on the analysis of the fracture development law of overlying rock in the mining of thick coal seam with weak and thin bedrock,combined with the actual production experience,the mechanism of water and sand bursting suppression in Yili Coal Field was studied.The results show that the arc-shaped surface tension cracks appeared 80~85m ahead of the mining direction of the working face,and the distance between the main and the secondary spot cracks was about 10m and 2m respectively;the development height of the water conducting fracture zone varied slightly when mining in the thick coal seam under the weak thin bedrock;the water inflow was less than 30m^3/h when mining in Yili Coal Field,and water and sand bursting was restrained.The main reasons for this occurrence was that larger rock blocks,voids and cavities failed to form mainly due to the weak lithology of the roof,the mining fissures were rapidly compacted as the mining went on;the fissures were filled with the outflow because of the loose overlying aquifer and were no longer enlarged under lower water pressure,and so.The research result shows significance to the prevention and control of roof water disaster and the protection of surface ecological environment in the mining of soft thin bed rock and thick coal seam in the western China.