某抽水蓄能电站地下厂房洞室群在锚杆锚固工况下围岩稳定性研究

Stability Analysis of Surrounding Rock of Underground Building Cavern Group in a Pumped Storage Power Station Under Anchoring Conditions

针对某抽蓄电站的地下厂房洞室群具有规模大,洞室密集,施工条件复杂,主要洞室边墙高、跨度大的特点,对洞室群在锚杆锚固条件下的围岩稳定性进行分析,采用基于快速拉格朗日差分分析方法的FLAC3D的数值分析方法,对某抽水蓄能电站地下厂房洞室群在无支护条件和有支护条件下的围岩稳定性进行计算,并对比分析该电站地下厂房洞室群在毛洞开挖和锚杆锚固条件下开挖前后的应力场以及围岩变形的分布特征和变化规律。结果表明:开挖后,洞周围岩变形总体上表现为向临空面发展,洞室的拱顶逐步下沉,底板回弹。支护措施能有效减小围岩变形,围岩塑性区明显减小,塑性屈服程度显著降低。对比支护前后,应力松弛范围明显减小,支护可以明显改善围岩最小主应力分布,并为围岩提拱有效的支护围压,提高围岩稳定性。

The cavern group of an underground powerhouse of a pumping and storage power station has the characteristics of large scale, dense cavern, complex construction conditions, high side wall of the main cavern and large span. The stability of surrounding rock of underground powerhouse cavern group of a pumped storage power station under bolt-anchored conditions is analyzed by a numerical analysis method FLAC~(3D) which adopted the fast Lagrange difference analysis method is used to calculate the stability of surrounding rock of underground powerhouse cavern group of a pumped storage power station under the condition of no support and with support. The stress field before and after excavation and the distribution and variation of surrounding rock deformation under tunnel excavation and bolt anchoring conditions are systematically analyzed, which provides reference and basic data for stability evaluation and engineering design of underground powerhouse cavern group. The results are as follows. After excavation, the rock deformation around the cave generally develops towards the open side, the vault of the cave gradually sinks, and the floor rebounds. The supporting measures can effectively reduce the deformation of surrounding rock, the plastic zone of surrounding rock is significantly reduced, and the plastic yield degree is significantly reduced. Compared with before and after the support, the stress relaxation range is obviously reduced, and the support can obviously improve the minimum principal stress distribution of surrounding rock, and effectively support the surrounding rock to lift the arch, and improve the stability of surrounding rock.