大型地下厂房洞室群施工期围岩变形分析

瀑布沟水电站地下厂房洞室群规模大,地质条件复杂,水平构造应力高,施工期围岩的变形及稳定问题突出。结合弹塑性有限元方法和围岩变形监测资料综合分析了地下厂房洞室群施工期围岩的变形特征及稳定性。结果表明:主厂房围岩变形最大,尾水闸门室变形次之,主变室变形最小,厂房上下游边墙位移随着厂房下挖逐级增大,在厂房中部下游边墙岩锚梁高程部位处实测最大位移为107 mm;厂房边墙位移在墙顶和墙底较小,墙中部较大,上游边墙位移总体大于下游边墙;厂房拱顶径向位移总体上很小,上、下游边墙在两端的副厂房和安装间变形较小,中部变形较大;数值计算结果和变形监测资料有较好的一致性,围岩变形受施工程序和地质条件的影响较大。

Deformation of Surrounding Rock Mass of Large Underground Powerhouse Cavern Groups during Their Construction

Because of the complicated geological condition and high horizontal tectonic stress, the deformation and stability of surrounding rock mass of underground powerhouse cavern groups is prominent in Pubugou hydropower station during their construction, which was analyzed by using elastic-plastic finite element method and analysis of deformation monitoring data. The results showed that: the maximum of deformation occurred in the surrounding rock of main power house, the second maximum in tail water gate chamber, and the minimum in transformer chamber; the displacement of upstream and downstream sidewalls increased along with powerhouse excavated step by step; the biggest monitoring deformation in middle downstream sidewall of rock anchor beam elevation was 107 mm; the displacement of sidewall was smaller in the top and bottom of wall and bigger in the middle; the deformation of sidewall upstream was bigger than that of downstream sidewall; the crown displacement is small as a whole; the upstream and downstream sidewall in the auxiliary powerhouse and erection bay on each side had a smaller deformation and that was bigger in the middle; the result of numerical calculation and monitoring data of deformation coincided well, and the construction program and geological conditions had a great effect on deformation of surrounding rock.