含水溶洞对采煤工作面覆岩移动的影响规律

含水溶洞的存在使得煤层覆岩移动规律存在特殊性。为了研究含水溶洞对煤层覆岩移动的影响,本文以贵州某矿作为工程背景,利用FLAC3D进行数值模拟研究,对比分析溶洞有无含水作用下煤层覆岩移动规律。研究结果表明:(1) 含水溶洞煤层开采情况下,溶洞围岩变形下沉量相较于无水情况增加了37.24%,随着推进距离的增加,溶洞靠近采空区侧底角出现明显的下沉现象,溶洞右帮出现向内挤压现象,溶洞围岩和煤层顶板应力集中区和破坏区逐渐贯通;(2) 溶洞含水情况相比于无水情况,覆岩运移在含水条件下得到加强,其中最大曲率增大了0.88mm·m-2、最大水平变形增大了1.81mm·m-1;(3) 随着采煤工作面的推进,含水溶洞围岩裂隙和煤层顶板裂隙不断扩展,当工作面推进至与溶洞水平距离小于10m时,溶洞围岩裂隙和顶板裂隙贯通,形成导水裂隙。研究成果对溶洞影响下的煤层开采顶板管理和地表沉陷防治具有理论和工程参考意义。

Study on the influence of water-bearing karst cave on overlying strata movement in coal mining face

The existence of water-bearing karst caves makes the movement law of coal seam overburden special. In order to study the influence of water-bearing karst cave on the movement of coal seam overburden, this paper takes a mine in Guizhou as the engineering background, uses FLAC3D to carry out numerical simulation research, and compares and analyzes the movement law of coal seam overburden under the action of karst cave with or without water content. The results show that: (1) In the case of water-bearing karst cave coal seam mining, the deformation and subsidence of the surrounding rock of the karst cave increased by 37.24% compared with the case without water. With the increase of the advancing distance, the karst cave near the bottom corner of the goaf appeared obvious sinking phenomenon, the right side of the karst cave appeared inward extrusion phenomenon, and the stress concentration area and failure area of the surrounding rock of the karst cave and the roof of the coal seam gradually penetrated. (2) Compared with the water-free condition, the overburden migration is strengthened under the water-bearing condition, in which the maximum curvature increases by 0.88 mm·m-2 and the maximum horizontal deformation increases by 1.81 mm·m-1. (3) With the advance of the coal mining face, the cracks in the surrounding rock of the water-bearing karst cave and the cracks in the coal seam roof continue to expand. When the horizontal distance between the working face and the karst cave is less than 10 m, the cracks in the surrounding rock of the karst cave and the cracks in the roof are connected to form water-conducting cracks. The research results have theoretical and engineering reference significance for roof management and surface subsidence prevention of coal seam mining under the influence of karst caves.