高应力大型地下厂房岩壁吊车梁原型观测与变形机理分析

Monitoring and deformation mechanism analysis on rock-bolted crane girders in large underground powerhouse in high geo-stress area

高地应力区大型地下厂房建设过程中,岩壁吊车梁作为重要结构物,其受力特征与安全稳定倍受关注。通过对高应力区锦屏一级水电站地下厂房岩壁吊车梁施工开挖期间和开挖完成后的安全监控,分析受到洞室开挖卸荷作用下,吊车梁锚杆受力特征、吊车梁与围岩间结合情况,对吊车梁进行安全评价。分析表明,高应力岩体卸荷调整引起岩体较大的变形和深部松弛,吊车梁锚杆应力水平较高,变化持续时间长,开挖期间快速增长,开挖全部完成后1年才逐步趋于稳定,应力值没有超过锚杆设计强度;基岩测缝计最大开合度为9.9mm,绝大部小于5mm。总体上,吊车梁处于正常工作状态。

Safety and mechanical characteristics of rock-bolted crane girders are important to construction of large underground powerhouses. For the underground powerhouse in the Jinping-I hydropower station located in a high geo stress area, mechanical characteristics of its bolts and attachment of its two crane girders to the surrounding rock are analyzed with safety monitoring at its excavation stage and a stage of 2 years later, and safety of its rock-bolted crane girders is evaluated. The results indicate that a larger deformation and deep relaxation of the surrounding rock could be caused by excavation and unloading of high geo-stress. And the stresses in the girder bolts that are generally at a high level, take a long time （roughly one year after the excavation） to reach stability. All the bolt stresses are below the yield strength of steel, and most of the joint openings between the girders and their surrounding rock are less than 5mm. with a maximum of 9.9mm.