不稳定围岩开挖与让压支护的优化设计及数值分析

Optimization design and numerical analysis of excavation and yield supporting for unstable surrounding rock

针对金川三矿区1165水平一大硐室的开挖与支护进行了有关优化设计和数值分析的研究,并提出了适当让压后支护的原则.结合现场调查提出了分3步开挖、9个让压支护方案;恰当地选取各种岩体及支护计算参数,并进行方案对比选出了最佳方案.该方案安全系数为1.44,最大位移量与实际相符;针对最佳方案进行了数值分析,结果表明,硐室拱顶最大位移量最终控制在157.7 mm左右;左上帮的最大位移量为266.2 mm;左下帮的最大位移量为189.4 mm;两帮水平应力和位移表现明显,塑性区域较大,可延伸到近10 m.表明适当让压后进行支护有利于围岩体的长期稳定.

In allusion to one larger cavity of 1 165 m level in Jinchuan Mine, optimization design and numerical analysis of excavation and supporting engineering were studied, and the idea of having support after appropriate yield was also put forward. According to local investigate results, the method of three step excavation, nine yield projects and corresponding supporting projects were presented. Nine projects were computed and compared based on various parameters of rock and supporting, the fifth project considered as the optimal one. Safety factor of the optimal project is 1.44, and max displacements match with local survey data. The optimal project was numerically analyzed. The results indicate that max displacements of cavity vault ultimately, top left side and lower left side respectively arrive at 157.7, 266. 2, 189.4 mm, and stress in circumjacent and vault of cavity surrounding rock are very concentrated, horizontal displacements and stress have strong behave result in biggish plastic area, the area extend to 10 m. Results of engineering application indicated that having supporting after appropriate yield is beneficial to long stability of surrounding rock.