厚松散层矿区开采沉陷拉伸区域土体内部变形演化规律研究——以淮北孙疃煤矿为例

Study on evolution law of internal deformation of soil mass corresponding to subsid-ence stretching area of thick loose layer mining areas:a case of Suntuan Coal Mine in Huaibei

为了研究厚松散层矿区开采沉陷拉伸区域相应土体内部变形演化规律,针对淮北孙疃煤矿10111,沿垂直于工作面推进方向,于拟采空区地表投影区域外侧(拉伸区域)以60 m间隔由近及远布设1~3号竖向钻孔;采煤沉陷过程中基于光纤(1号钻孔)、测斜仪(2~3号钻孔)技术开展钻孔变形监测;将煤炭开采引发移动的上覆岩层与松散层所占区域视为变形区,并引入任意厚度地层移动角的概念,分析开采沉陷拉伸区域相应松散层变形演化特征。结果表明:1号钻孔发生应变的最大孔深约157 m,且钻孔深部较浅部先达到活跃期;2、3号钻孔孔口最终累计水平位移量分别为129.8 mm和99.4 mm,最大位移深度分别约为108 m和75 m;2、3号钻孔监测范围内地层从下至上均可分为稳定段、变形区下段、中段与上段;2、3号钻孔从下至上水平位移量总体分布较均匀,每米深钻孔的平均水平位移量分别约为1.2 mm和1.3 mm;2、3号钻孔变形区下段均先于上段达到活跃期,且变形区下段稳定后上段仍有微弱变形;松散层内一定厚度地层,其地层移动角随地层深度的增加而增加,松散层变形区下边界的深度h随着与工作面水平距离l的增加而减小,h与l满足指数函数关系。

To study the internal deformation evolution law of soil mass corresponding to subsidence stretching area of mining areas with thick loose layer,the No.10111-working face of Suntuan coal mine in Huaibei is selected,and No.1—3 vertical boreholes are arranged at 60 m spacing along the direction perpendicular to the advancing direction from the near to the distant for the loose layer corresponding to stretching area of the working face.In the process of coal mining subsidence,the borehole deformation monitoring is carried out based on the technology of optical fiber(borehole No.1)and inclinometer(borehole No.2-3).The area occupied by the overlying rock strata and loose layers mobilized by coal mining is considered as a deformation zone,and the concept of the movement angle of strata of arbitrary thickness is introduced.The results show that:The maximum depth at which strain occurs in the borehole No.1 is about 157 meters,with the deeper sections of the borehole reaching the active phase before the shallower;Within the monitoring range of boreholes No.2 and No.3,the geological formations can be divided from bottom to top into stable sections,lower,middle,and upper sections of the deformation zone.The final cumulative horizontal displacement at the borehole openings of No.2 and No.3 is 129.8 mm and 99.4 mm respectively,and the maximum displacement depths of about 108 m and 75 m respectively;Moreover,the horizontal displacement distribution of No.2 and No.3 borehole from bottom to top is generally uniform,and the average horizontal displacement per meter borehole is about 1.2 mm and 1.3 mm,respectively;In each borehole,the lower part of the deformation zone reaches the active period before the upper part and the upper part still has weak deformation after the lower part of the deformation zone is stable;For a certain thickness of strata in the loose layer,the movement angle increases with the increase of its depth,and the depth h of the lower boundary of the loose layer deformation zone decreases with the increase of the horizontal distance l from the working face,which accords with the exponential function relationship.