大型地下洞室群稳定性地质力学模型试验研究

Experimental Study on the Stability of Large Underground Cavern Group by Geo-mechanical Model

某地下厂房洞室群规模巨大,地质条件复杂,为了研究地下洞室群开挖施工过程中的应力及稳定情况,采用平面地质力学模型试验,模拟厂区实际地质条件和洞体结构,施加初始地应力荷载,分别对毛洞情况和支护情况按推荐开挖顺序进行试验研究。试验结果表明,毛洞情况开挖过程中洞周位移未发生突变,开挖完毕后,洞周围岩位移均指向洞内,位移量值不大,洞周围岩未出现切向拉应力,围岩具有一定的超载安全储备。锚固支护后,洞周位移减小,洞周围岩应力分布趋于均匀,应力状态得到改善,超载安全系数得到提高,锚固支护效果明显,除了洞室交叉口和洞室拱座处局部发生应力集中外,整个洞室群开挖后围岩应力分布规律正常,应力状态良好,说明施工开挖方式和锚固支护参数是合理的。模型试验和三维非线性有限元计算结果相比较,位移变化规律、破坏形态规律基本一致,从而达到了相互验证的目的。

There is a large scale underground power house cavern group and its geological conditions are rather complicated. In order to research the stress and stability during construction,a plane geo-mechanical model test is conducted to simulate the actual geological conditions and cavity structure. Initial ground stress is applied;unsupported and supported conditions are tested according to the recommended excavation sequence. The results showed that there is no mutation of the displacements of the surrounding rock in unsupported underground caverns during excavation. After excavation,displacements point to cave,displacement magnitude is small,and tensile stress doesn't appear around surrounding rock. Surrounding rock has a certain overload safety reserve. After anchoring support,the displacements reduce. Stress state is improved as the distribution tends to be uniform. Anchor support effect is obvious as overload safety factor is improved. Stress concentrates only in cavern intersection and abuts,while stress distribution law is normal of surrounding rock after excavation. It showed the excavation methods and anchor support parameters are reasonable. Compared results of model tests and numerical calculation,both the displacement variation rules and destruction mode are consistent,so as to achieve the purpose of mutual verification.