岩滩水电站扩建工程地下厂房围岩变形反馈分析

岩滩水电站扩建工程地下厂房开挖尺寸大、地质条件复杂、开挖工期长,为了保证施工期的安全,需准确地了解地下厂房施工期围岩的稳定性。通过实测的地应力及现场岩石力学试验获取围岩稳定性计算初始参数,利用遗传算法优化的BP神经网络和安全监测实测位移值反演岩体力学参数,进而采用三维有限差分法反演获取地下厂房各开挖步的围岩稳定情况。岩滩水电站扩建工程地下厂房开挖后,围岩变形总体较小,塑性区分布有限,洞室群围岩稳定性良好。应力集中及塑性区比较集中的部位主要位于主厂房底部边墙与尾水管周围,该区域开挖时须加强支护跟进及监测工作。

Feedback Analysis on Underground Powerhouse Surrounding Rock Deformation in Extension Project of Yantan Hydropower Station

The underground powerhouse of Extension Project of Yantan Hydropower Station has the characteristics of large excavation size, complex geological conditions and long period of excavation. Stability of the surrounding rock must be obtained accurately to ensure the safety during construction period. The initial parameters of surrounding rock stability calculation could be acquired through the in-situ stress test and rock mechanics field test. And the rock me- chanics parameter could be acquired by using optimized BP neural network and monitoring displacement values. Fi- nite difference method is employed to retrieve the stability of surrounding rock of underground powerhouse of each excavation step. The surrounding rock deformation and plastic zone distribution is small after excavation, and the sta- bility of surrounding rock is in good condition. Concentrated stress and plastic zone is relatively concentrated at the bottom wall of main powerhouse and around the draft tube. The excavation of this region should be followed by the shotcrete and bolt support and safety monitoring work in time.