关键词: 长甸水电站, 引水隧洞, 低水位运行, 深埋, 外水压力, 有限元

Abstract: The headrace tunnel of Changdian hydropower station has been in operation with low water level or shut-down condition for a long time after completion. Due to the large buried depth, poor geological conditions and high external water pressure on the middle section of the tunnel, the huge difference between actual operation state and the design condition is harmful to the tunnel safety. The operational safety of the section with maximum buried depth is calculated and analyzed by 3D finite element method. The results show that the operational safety of surrounding rock with long-term low water level can be guaranteed by existing supporting measures, but the safety margin is not much large. Therefore, it is suggested to evaluate the safety status of the surrounding rock regularly in the future, in combination with site conditions.

Key words: Changdian hydropower station, headrace tunnel, running with low water level, deep-buried, external water pressure, finite element method