地下厂房岩锚梁裂缝成因分析

针对水电站地下厂房开挖过程中出现的岩锚梁与围岩结合部位的纵向裂缝,结合地质资料、监测成果和施工过程,对岩锚梁裂缝产生的原因进行较为详细的分析,认为裂缝形成的时间在2006年10月底至11月初,即地下厂房进行第Ⅴ层开挖施工期间;裂缝段围岩的差异变形是裂缝产生的主要原因;导致围岩差异变形的地质原因是存在岩脉断层,施工原因是支护措施不能有效地节制围岩变形.因此,考虑岩体的非连续性,加强施工期地质工作,及时预测侧墙可能出现的差异变形,并采取有力的支护措施对确保岩锚梁安全十分重要.

CAUSES ANALYSIS OF CRACKING OF ROCK-BOLTED CRANE GIRDER IN AN UNDERGROUND POWERHOUSE

Rock-bolted crane girder is a widely used structure in underground powerhouse nowadays.In hydropower projects longitudinal crack between rock-bolted crane girder and surrounding rock masses can hardly be found.Aiming at the cracking phenomenon in an underground powerhouse,detailed analysis of the cracking mechanism is made based on geology,monitored data and construction process.It is concluded that the cracking initiates between late October and early November,2006;differential deformation caused by vein faults in the surrounding rock and excavation is the major cause leading to the cracking while the development of the differential deformation cannot be effectively controlled by support measures.So considering the discontinuous characteristics of rock masses,it is important to make detailed geological investigation and to forecast possible differential deformation on the sidewalls during construction period,so as to take effective support measures and assure the safety of the girder.