大型地下厂房围岩预应力锚固施工新技术应用

New technologies for pre-stressed anchoring construction of surrounding rock of large-scale underground powerhouse

彭水水电站建于地质条件复杂的岩溶地区,主厂房洞室规模巨大,围岩为顺岩层走向的陡倾角层状页岩体。针对薄层、陡倾角、软弱页岩自稳时间短、变形破坏机制不易被掌控等特点,在施工控制上应重点考虑降低出露围岩的应力松弛、卸荷变形,及早施加支护锚固力,解决顺岩层布置大型地下洞室高边墙的围岩稳定等问题。为此,全面采用中空注浆预应力锚杆新技术,及时加固浅层围岩;以钢垫板锚墩替代混凝土锚墩,简化了施工工艺、保证了工程质量、加快了施工进度,使围岩及时得到深层锚固力,降低了围岩卸荷变形的可能。

Pengshui Hydropower Station is built in geological complicated karst area with huge cavern for main powerhouse,and the surrounding rock is along the strike of strata and steep-dip shales.For the characteristics of thin layer,steep dip,short self-stabilization time and difficult understanding of deformation and failure mechanism of weak shale,the key point for construction is to reduce stress relaxation and unloading deformation of the outcropped rock mass and anchoring timely to stabilize the surrounding rock mass of high side-wall of power house cavern constructed along the strike of strata.We systematically use new technologies of pre-stressed hollow grouting for anchoring to strengthen shallow rock mass timely,replace concrete anchor pier with steel plate anchor pier which simplifies the construction process,ensures the construction quality and accelerates the construction progress.Therefore,surrounding rock is deeply anchored timely which reduces the probability of unloading deformation of surrounding rock mass.