急倾斜特厚煤层分段开采覆岩活动规律研究

Study on overburden strata activity law for mining in sectional seam of steep inclined ultra thick seam

为了揭示急倾斜特厚煤层水平分段综放开采条件下的覆岩活动规律,采用相似材料模拟试验,研究了不同水平分段开采后急倾斜煤层覆岩破坏过程、应力场变化和顶板沉陷规律。研究表明:覆岩的破裂经历裂隙产生、顶板离层、离层扩展、顶板垮落4个过程,自然垮落条件下,急倾斜煤层覆岩垮落存在滞后性,悬顶破断可能引发顶板大面积垮落、冲击地压等动力灾害;覆岩垮落移动时,顶板局部应力畸变,出现拉应力,底板压应力呈线性增加,直至破坏失稳;覆岩顶板离层量自下往上逐渐减少,岩层垮落后,顶板下沉最大位置沿倾斜方向向上方转移,直至地表沉陷。

In order to reveal the overburden strata activity law under the fully-mechanized top coal caving mining in the horizontal sectional seam of the steep inclined ultra thick seam, a similar material simulation test was applied to study the overburden strata failure process, stress field variation and roof subsidence law of the steep inclined thick seam after the mining in deferent horizontal sectional seam.The study showed that the fracturing of the overburden strata had a cracking occurrence, roof bed separation, bed separation expansion, roof fall- ing processes.Under the condition of the natural roof falling, a delay was existed in the overburden strata falling of the steep inclined thick seam and the suspended roof breaking could cause a large area roof falling, roof strata bumping and other dynamic disaster. During the over- burden strata falling and displacing,local stress of the roof would be distortion, a tensile stress would be appeared, the floor pressure stress would be increased in a linear and then until the roof failed and the stability lost.The roof separation quantity of the overburden strata would be steadily decreased from the bottom to the top.After the rock strata failed, a larger location of the roof subsidence would be upward migra- ted along the inclined direction, until the surface ground subsided.