巨型地下厂房创新支护技术应用

Application of innovative support technology in giant underground powerhouse

白鹤滩水电站地下厂房位于高地应力区,洞室群规模巨大、挖空率高,围岩以Ⅲ_1类玄武岩为主,大型层间层内错动带、柱状节理玄武岩和陡倾角长大裂隙等不良地质构造发育,洞室群效应明显,围岩稳定问题突出,开挖成型困难。为此,地下厂房开挖过程中拟采用硅粉喷射混凝土、新型锚索锚固材料,以达到快速支护的目的;利用全螺纹树脂锚杆提高岩锚梁成型质量;采用混凝土提前置换错动带以有效控制围岩变形。详细介绍了上述一系列支护技术的应用情况及控制技术。工程实践证明,上述措施实施后很大程度上保证了地下厂房开挖成型与围岩稳定。

The underground powerhouse of Baihetan Hydropower Station is located in the high ground stress area.Its cavern group scale is huge,excavation hollowing rate is high,and surrounding rock is mainly type Ⅲ1 basalt.Its geological structure is poor with large-scale inter-layer and intra-layer dislocation interfaces,columnar joint basalt,steep dip angle,long cracks and so on.The effect of cavern group and the instability of surrounding rock make the excavation difficult.Therefore,in the excavation process of underground powerhouse,the silica spray concrete and new anchor cable anchoring material was used to achieve the purpose of rapid support,and the molding quality of rock anchor beam was improved by using fully threaded resin anchor rod.In order to effectively control the deformation of surrounding rock mass,concrete was used to replace the dislocation belts in advance.After the application of these techniques,the underground powerhouse excavation and the stability of surrounding rock were ensured.