Support technology for mine roadways in extreme weakly cemented strata and its application

For the engineering geology conditions of bad mine roadway roof and floor lithology in extremely weak cemented strata, the best section shape of the roadway is determined from the study of tunnel surrounding rock displacement, plastic zone and stress distribution in rectangular, circle arch and arch wall sections, respectively. Based on the mining depth and thickness of the coal seam, roadway support technology solutions with different buried depth and thickness of coal seam are proposed. Support schemes are amended and optimized in time through monitoring data of the deformation of roadway, roof separation, l-beam bracket, bolt and anchor cable force to ensure the long-term stability and security of the roadway surrounding rock and support structure. The monitoring results show that mine roadway support schemes for different buried depth and section can be adapted to the characteristics of ground pressure and deformation of the surrounding rock in different depth well, effectively control the roadway surrounding rock deformation and the floor heave and guarantee the safety of construction and basic stability of surrounding rock and support structure.

Plastic zone analysis and support optimization of shallow roadway with weakly cemented soft strata

Based on a shallow roadway with weakly cemented soft strata in western China, this paper studies the range and degree of plastic zones in soft strata roadways with weak cementation. Geological radars were used to monitor the loose range and level of surrounding rocks. A mechanical model of weakly cemented roadway was established, including granular material based on the measured results. The model was then used to determine the plastic zone radium. The predicted results agree well with measured results which provide valuable theoretical references for the analysis of surrounding rock stability and support reinforcing design of weakly cemented roadways. Finally, a combined supporting scheme of whole section bolting and grouting was proposed based on the original supporting scheme. It is proved that this support plan can effectively control the deformation and plastic zone expansion of the roadway surrounding rock and thus ensure the long-term stable and safe mining.

西部弱胶结软岩巷道新型聚合物喷层支护研究

针对传统的喷射混凝土喷层力学性能不均一,延伸性能差,难以较好封闭支护围岩,影响围岩力学特性和支护结构稳定的问题,结合西部软岩巷道工程地质条件和矿压显现规律,在传统喷射混凝土材料配比的基础上,通过室内材料配比试验确定了新型聚合物喷层的材料配比和力学性能,研发的聚合物喷层强度高,抗裂性能和延伸性能好,能够适应软岩巷道大变形的支护要求。在红庆梁煤矿总辅运大巷岩巷试验段进行工业性试验,并通过6个月现场监测可知,无水段巷道喷层差异不大,而在淋水段巷道新型聚合物喷层完整性好,围岩稳定性好,锚杆锚索受力小,所以新型聚合物喷层能有效封闭西部弱胶结软弱围岩,维持巷道的长期稳定。

深埋采场压架切顶诱发井下泥石流形成机理与防控

随着西部黄陇煤田煤炭资源的大规模开发与利用,该地区出现了一种危害严重的新型顶板灾害:采场压架切顶诱致井下泥石流灾害。由于事故采场埋深大、基岩厚,导致其与西北浅埋煤层和华北近松散层煤层采场遇到的压架切顶和溃水溃沙(砂)灾害,以及金属矿井下泥石流和煤矿断层、采空区泥石流灾害在物源和动力源上均有所不同。为防止该类型灾害再次发生,采用理论分析、数值计算和室内试验等手段,从灾害形成的物源、动力源及其影响因素等角度,分析研究了采场覆岩破坏特征、支架合理工作阻力、工作面节理裂隙发育产状、临近工作面倾斜支承压力叠加影响、含水层水力梯度条件和弱胶结地层物理力学特征及其矿物成分等,揭示了事故采场压架切顶和井下泥石流灾害的形成条件和2者的内在联系。研究结果表明:该类型灾害形成包括客观必要条件和诱发因素,客观必要条件为包含大量亲水矿物的弱胶结直罗组泥岩类顶板地层(物源)和复合关键层滑落失稳(动力源),诱发因素为支架工作阻力过小、临近工作面倾向支承压力叠加影响、工作面推进速度缓慢、顶板含水层较大的水力梯度和工作面顶板节理裂隙产状特征,即在客观必要条件存在的情况下,多个灾害诱发因素叠加导致客观必要条件灾变。因此,针对该灾害类型形成了"查清客观必要条件、控制和避免诱发因素"的防控技术路线。