Large Section Cavern Excavation With The Surrounding Rock Stability Problems

Based on the construction project of underground structures of Longtan hydropower station, the key technology problems in the construction are dealt with and then measures and conclusions are advanced by this thesis. The main study contents are listed as fllowing:1. excavation technology of large-section cavityExcavation layout, minig sequence, minig technology are studied in the thesis. Through summarizing construction process of the project and analyzing excavation technology of large-section cavity, the deformation law of surrounding rock is drawed on the basis of monitoring data, geological data and actual surrounding rock condiation. Then reseanable timbering time-span under different surrounding rock conditions is determined and an economical and reasonanble construction way is found for attaining the goal of quick, economical, safe and quality-assuring management.2. study on the stability of large-section cavityBaesd on the monitoring data and actual rock layers condition and comparity with academic results, the stability of cavity is studied and the deformation law of surrounding rock is found.Through analyzing the stability of cavity, the corresponding measures are applied to resolve the problem of unstability of local unstable rock to assusre safe construction and rock stability; at the same time, layer hight is adjusted , and timbering is applied to excavation front immediately in the construction work of IV rock condition through stability analysis to assure surrounding rock stability and safe construction and function.