猴子岩水电站地下厂房围岩变形特征分析与控制

Analysis of deformation characteristics of surrounding rock of underground powerhouse of Houziyan Hydropower Station and its control

结合地质、监测及施工资料,对猴子岩地下厂房施工期围岩变形特征进行分析,结果表明,厂房围岩具有高地应力条件下围岩变形的显著特点,如围岩位移量级偏大、围岩变形时效性显著、混凝土喷层开裂等。地下厂房围岩变形发展随着逐步开挖不再表现为单一的"台阶型",部分测点呈现出"阶段-应力控制型"发展特征;在高地应力条件下,围岩变形呈现出渐进扩展的趋势,松弛深度逐步向岩体内部发展。通过对围岩变形历史峰值速率和支护时间的分析,提出了控制围岩变形的主要措施与建议,如开挖方式采取深孔预裂、浅层开挖,提高锚索设计吨位、降低锁定吨位,重视浅层支护、低压固结灌浆等。

With consideration of geological, monitoring and construction data, the deformation characteristics of surrounding rock of underground powerhouse in construction period was analyzed. The results show that the deformation of surrounding rock has obvious high geo-stress features, such as large magnitude of displacement, obvious timeliness of deformation and shotcrete layer cracking, etc. With the excavation progress, the deformation development did not appeared as a single＆quot;staged＆quot; type, but some of the measured points were characterized as＆quot;stage-stress controlled＆quot; type. Under high geo-stress, the deformation de-veloped gradually and the relaxation depth developed toward the inner part of the rock body step by step. Through analysis of his-torical peak deformation rate and supporting time, the measures and suggestions to control the deformation were put forward, such as deep hole presplitting and shallow excavation, increasing the designed tonnage of anchor cable, paying attention to shallow support and consolidation grouting under low pressure.