针对目前深部大断面回采巷道控制难题和相应的高强锚索控制技术,考虑顶板围岩应力与支护荷载影响,利用Hoek-Brown强度准则及塑性力学中的极限分析上限法,得到了大断面巷道顶板的冒落破坏机制,提出了顶板锚索长度及匹配预紧力的设计方法。基于建立的锚索设计参数影响因素敏感性指标对巷道宽度、岩体重度、围岩应力、岩体抗压强度、抗拉强度、锚索布设间距、顶角锚索布设倾角等因素的影响进行了分析。结合现场实际情况,提出了深部大断面回采巷道围岩控制的工程建议。将此设计方法应用到千米深井赵楼煤矿1305孤岛工作面的运输顺槽顶板锚索参数确定中,有效地控制了围岩变形。研究表明:在高应力大断面回采巷道中,顶板锚索需锚固在稳定岩层中,并施加足够的预紧力,才可有效控制顶板围岩冒落或破坏;顶板锚索所需预紧力随岩体抗拉强度、抗压强度及岩体经验参数A的增大而减小,随巷道宽度、岩体重度、围岩应力、锚索布设间距、顶角锚索布设角度以及岩体经验参数B的增大而增大,其敏感性最高的影响因素为围岩应力。因此,在深部高地应力巷道设计中,需特别重视地应力的影响,采用高强、高延伸率锚索,增设锚索定量让压装置,高阻让压有效释放围岩应力,并通过施加高预紧力或注浆加固等方式来提高围岩完整性,获得较好的围岩控制效果。
The aim of this study is to resolve the present control problems and the corresponding high-strength anchor cable control technology in deep large section roadways. This study was based on the Hoek-Brown criterion and the upper bound theorem of the limit analysis and also considered the stress of surrounding rock in the roof and the effect of supporting the load. On the above basis, the roof caving mechanism of large-section roadways was acquired. Furthermore, a design method for roofs was put forward for the minimum length and the pre-tightening force of an anchor cable. Since the design parameters of anchor cables was affected by established sensitivity indexes, it is important to investigate the effects of established sensitivity indexes on factors, such as the roadway’s width, the specific weight of the rock mass, the stress in the surrounding rock, the compressive strength and the tensile strength of the rock mass, anchor cable layout spacing and vertex anchor cable laying angle. According to the actual field conditions, engineering suggestions are proposed for controlling surrounding rocks in the deep large-section roadway. Finally, this design method was applied to determine the roof anchor parameters of transport gateway of 1305 Island Coal Face in the Kilometer Deep Well Zhaolou coal mine, which effectively controlled the deformation of surrounding rock. From research results, only when the roof anchor cable was anchored in stable rock and enough pre-tightening force was exerted, the roof rock caving and damage can be effectively controlled in high-stress large-section mining roadways. It is found that roof pre-tightening force for anchor cable decreased with the increase of tensile strength, compressive strength and empirical parameter A of rock mass. Besides, this roof pre-tightening force increased with increasing the width of the roadway, the specific weight of rock mass, the stress in the surrounding rock, the compressive strength and the tensile strength of rock mass, anchor cable layout spacing, vertex anchor cable laying angle and empirical parameter B of rock mass. Moreover, the highest sensitivity of all the influencing factors turned out to be the surrounding rock stress. This indicates that special attention should be paid to the influence of in-situ stress of the surrounding rock when designing the deep high-stress roadways. Therefore, the effective release of the surrounding rock stress can be achieved by using the high strength, high elongation anchor cable and adding the yieldable device. Meanwhile, the integrity of the surrounding rock can be improved by applying high pre-tightening force and grouting reinforcement, resulting in better control performance of surrounding rock.