深部大变形巷道围岩稳定性控制方法研究

Stability control method of surrounding rock in deep roadway with large deformation

针对深部高应力巷道围岩大变形难以控制的问题,采用Kastner等相关理论,研究了支护阻力对深部高应力巷道围岩变形的影响,揭示了其变形难以控制的力学本质,提出了巷道围岩稳定性控制新的支护理念。深部高应力巷道围岩大变形主要来自于两部分:1巷道周边浅部破碎围岩的扩容与剪胀等非连续性变形;2高应力致使巷道围岩产生的以塑性变形为主的连续性变形。研究表明:目前的支护水平对巷道围岩的连续性变形影响十分有限,总是存在一部分变形量无法控制,即深部巷道围岩存在"给定变形"。为实现巷道围岩稳定控制,降低支护成本,巷道围岩支护理念应由变形控制向稳定控制转变,确保巷道围岩均匀、协调变形,消除冒顶与片帮等不安全隐患,增强巷道围岩整体性与稳定性。因此,对于深部高应力巷道围岩稳定性控制,可在巷道掘进时预留一定的变形空间以容纳围岩部分"给定变形",支护结构应具有一定的连续性变形能力,又能持续提供较高的支护阻力,以维持巷道围岩的完整性与稳定性,保障巷道围岩的均匀、协调变形。工程实践结果表明:考虑预留变形并采用"可接长锚杆+刚性长螺纹钢锚杆+锚网+W钢带+喷射混凝土"综合控制技术为主,并辅以可接长锚杆强化顶板支护方案可较好控制巷道围岩的稳定性,保障了巷道服务期间的安全使用。

To investigate the surrounding rock control of deep roadway with large deformations, the theories, such as Kanstner theory, were applied to study the influence of supporting resistances on the surrounding rock deformation in roadways subjected to high in situ stress. The mechanical essences of the difficult control of these deformations were discovered, and the new supporting concepts of roadway stability were then proposed. The large roadway deformation mainly consists of discontinuous deformations that result from the shear dilation and dilation of shallow fractured sur- rounding rocks and the continuous deformations that mainly result from the stress-induced plastic deformations. Results indicate that the present supporting system exerts limited influences on the continuous deformation, a part of the de- formation cannot be successfully controlled, that means ＇ given deformations＇ are encountered. To successfully control the roadway deformation and significantly reduce support cost, the support concept should be transferred from deforma- tion control to stability control. This transfer will ensure the even distributions of in-situ stress, coordinated deforma- tions and the eliminations of roof falling and wall caving. Thus, the integrity and stability of surrounding rocks will be further enhanced. In the excavation process of roadways, the enlarged roadway sections that can tolerate the ＇ given de- formations＇ and the support system that can continuously deform will provide higher support resistances. Therefore, the integrity and stability of roadway are ensured. Even and coordinated deformations of roadway will be successfully ful- filled. The practice results show that the support mainly by the integrated control technology of reserved deformation and ＂addable lengthen bolts ＋ stiffness thread steel lengthening bolts＋bolting net＋W steel belt＋sprayed concrete＂ and supplemented by the scheme of addable lengthen bolts strengthen roadway roof can control the stability of roadway sur- rounding rock effectively, and ensure the safety of roadway during its service.