乌东德水电站洞室开挖围岩应力重分布的数值分析

Numerical Analysis on Stress Redistributions in Surrounding Rock of Underground Caverns in Wudongde Hydropower Station

为研究锚杆支护作用对乌东德水电站地下洞室围岩应力状态的影响,采用FLAC 3D软件进行数值模拟分析。模拟结果表明,设置锚杆支护提高了洞室开挖过程中围岩的最小主应力,围岩整体稳定性大幅提高;在地下洞室开挖面的顶板、顶板与侧墙以及四周全断面分别设置锚杆支护,得到的最大主应力增量分别为0.93、2.46 MPa和6.50 MPa,说明锚杆安装在四周的工况对围岩稳定最为有利;锚杆数量、长度和预应力对围岩应力重分布均有明显影响,当单侧锚杆的数量、长度和预应力分别为5根、2.0 m和60 kN时,可形成完整的圆弧应力拱,提高了开挖面围岩的整体稳定性。

In order to study the influence of bolt support on the stress state of surrounding rock in underground caverns of Wudongde Hydropower Station,the FLAC 3D software is used for numerical simulation analysis.The numerical results show that,(a)the bolt support can improve the minimum principal stress of surrounding rock during cavern excavation process,and the overall stability of surrounding rock is greatly improved;(b)the maximum principal stress increment values are 0.931,2.46 MPa and 6.5 MPa respectively under three support schemes of allocating bolts in cavern roof,roof and side walls and all around the cavern,indicating that the scheme allocating bolts all around the cavern is most beneficial to the stability of surrounding rock;(c)the quantity,length and pre-stress of bolts have significant influence on the stress redistribution of surrounding rock,and when the number,length and pre-stress of single-sided bolt are 5,2.0 m and 60 kN respectively,a complete arc stress arch can be formed and the overall surrounding rock stability of the excavation surface can be improved.