中文摘要：

为了探究大断面切眼顶板控制机理,以某煤矿5205切眼为工程背景,采用UDEC4.0模拟了切眼宽度6~10 m过程中,顶板偏应力、裂隙场、变形规律等响应特征。结果表明:①顶板偏应力呈浅部逐渐升高,深部逐渐降低的分布形态,宽度越大顶板浅部偏应力越小,而深部偏应力越大,同时,偏应力极大值逐渐降低并向深部转移。②围岩裂隙场分为3个区:裂隙贯通区、裂隙发育区、微裂隙区,均呈'半椭圆'状。③切眼宽度的增加,加剧了顶板微裂隙区向裂隙发育区及裂隙发育区向裂隙贯通区的转化,同时,顶板下沉增大。认为:顶板的控制首先保证帮不稳定三角块的稳定;高性能锚杆可更好地控制裂隙滑移。④双桁架锚索可锚固在肩角无裂隙区和顶板深部预应力叠加区,可抑制顶板中部裂隙贯通区的拓展和变形。基于此提出了高强高预紧力锚带网和双桁架锚索联合控制技术,矿压结果:切眼掘出后10 d实现自稳,顶底板相对移近量128 mm,两帮相对移近量96 mm,顶板离层4 mm。

英文摘要：

To study the control mechanism of large-section open-off cut roof, No. 5205 open-off cut in a coal mine is selected as an engineering case. The deviatoric stress of roof, fracture field and deformation law are investigated by UDEC4.0 in the change process of width from 6 to 10 m. The results show that:(1) The deviatoric stress of roof gradually increases in shallow part and decreases in deep part. The wider the open-off cut, the lower the deviatoric stress in shallow part and the higher in deep part and the same time the peak of deviatoric stress is moving to the deeper part;(2) The fracture fild in surrounding rock were divided into three areas:fracture transfixion area, fracture area and microfracture area, which distributed as semi-ellipse;(3) With the width of open-off cut increasing, The trend of microfracture area transformed to fracture area and fracture area transformed to fracture transfixion area are strengthed in the roof. Besides, the roof subsidence is aggravated. It believed that:(1) The stability of unstable triangle block is the more important to keep roof safe;(2) High-performance bolt can control fracture slip preferably;(3) Double-truss and anchor rope can be anchored in the shoulder non-fracture area and deep roof pre-stressed superimposed area, which can control the expansion and deformation of fracture transfixion area in the middle part of the roof. Based on this, the combined support technology of high-strength and high pre-tension bolt&net &bar and double-truss and anchor rope is proposed. The observed results of mining pressures show that the open-off cut is self-stabilized after it is dug out for 10 days; the relative convergence of roof-to-floor is 128 mm; the relative convergence of both sides is 96 mm; and the separation of roof is 4 mm.