坪头水电站1~#竖井的开挖与支护

坪头水电站1#竖井总高度为102.2 m,开挖直径为5.6 m,所处地层为微风化至强风化的细晶白云岩,为Ⅲ~Ⅳ类围岩,极易产生塌方、掉块。通过对1#竖井这种复杂地质条件下开挖与支护施工的方法研究与实践,探索了竖井的导井法施工、开挖前回填灌浆与开挖中的喷锚支护、钢支撑加强支护,对塌方区域采取模喷、回填浇筑等处理方法,总结出对极其复杂地质条件下的竖井开挖与支护分别采取预固结灌浆、锚喷支护、钢支撑加固以及模喷、回填浇筑的综合施工方法。

Excavation and Support of Shaft No.1 in Pingtou Hydropower Station

Shaft No.1 of Pingtou Hydropower Station is 102.2 m in height,its excavation diameter is 5.6 m,and it is located at the stratum that is consisted of the fine grain dolomite being silkily weathered to highly weathered,which belongs to Ⅲ~Ⅳ surrounding rock,and the occurrences of collapses and drops are highly possible.By researching and practising the excavating and supporting methods under the complicated geological conditions of Shaft No.1,such treating methods as pilot shaft construction,backfilling concrete before excavation,shotcrete and rock bolt supporting in excavation,steel bracing to strengthen the support,as well as shotcreting after formwork and backfill concreting in collapsed areas etc.are explored here in detail.For the excavation and support of shaft under extremely complicated geological conditions,it’s concluded that the comprehensive construction methods of pre-consolidation grouting,shotcrete and rock bolt supporting,steel brace strengthening,formwork-shotcreting and backfill concreting should be taken respectively.