断层破碎带中巷道围岩大变形机理及控制技术研究

Study on the mechanism and control technology of large deformation of roadway surrounding rock in the fault fracture zone

基于常村煤矿N3-6运输平巷的地质状况,分析了过断层破碎带时巷道围岩大变形的机理,得到了巷道在断层破碎区域大断面效应显著,且围岩变形受构造应力机制(IIA)、重力机制(IIB)和随机节理型机制(IIIE)的复合变形力学机制作用是巷道围岩大变形的主要原因;在一定范围内,随着Hoek-Brown常数(m1)、岩体地质强度指标(GSI)和岩石单轴抗压强度(c)的提高,巷道围岩失稳范围迅速减小;随着围岩应力增加,失稳范围逐渐加大,二者近似于正比例关系。提出了"超前预注浆+锚网索"联合支护方式控制断层破碎区域围岩变形,通过FLAC^(3D)数值模拟对比了原方案和优化后方案的支护效果,结果表明,优化后方案围岩塑性区面积较原方案下降低了56.9%,顶底板最大位移量减小了74%,两帮最大位移量减小了65.3%,巷道围岩大变形得到了有效控制。工业性试验表明,巷道围岩变形在25 d后基本趋于稳定,且顶底板位移量以及两帮位移量均控制在300 mm以内,与FLAC^(3D)数值模拟结果基本吻合,运输平巷支护效果能满足工程需求。

Based on the geological condition of Changcun coal mine＇s N3-6 haulage drift, the mechanism of large deformation of surrounding rock in the fault fracture zone was analyzed. Results show that the large section effect of the roadway in the fault fracture zone is remarkable. The large deformation of roadway surrounding rock is attributed to the composite mechanism including the tectonic stress mechanism（IIA）, in-situ stress mechanism（IIB） and random joint mechanism（IIIE）. Within limits, as the Hoek-Brown constant, geological strength index of the rock mass and uniaxial compressive strength of the rock increase, the instability scope of roadway surrounding rock decreases rapidly. The surrounding rock stress is approximately in direct proportion to the instability scope. The combined supporting method, i.e., ＂advance pre-grouting ＋ cable anchor＂ was proposed to control the surrounding rock deformation in the fault fracture zone. The supporting effect of the original scheme was compared with the optimized one using the numerical simulation（FLAC^3D）. Results indicate that the plastic zone area of the surrounding rock in the optimized scheme is reduced by 56.9%, while the maximum displacement of the roof and floor decreases by 74%. In addition, the maximum displacement of roadway＇s sides decreases by 65.3%. The large deformation of roadway surrounding rock has been effectively controlled under the optimized scheme. Industrial test shows that the deformation of roadway surrounding rock tends to be stable after 25 d, and the displacements of two sides, top and bottom plate of the roadway are controlled within 300 mm. The supporting effect of the haulage drift can satisfy the engineering demand.