巴拉水电站首部枢纽导流洞坍塌冒顶处理

Treatment on the Collapse and Roof Fall in the Diversion Tunnel of the Headworks of Bala Hydropower Project

近几十年来,随着隧洞设计和施工技术的不断创新,超大断面无压输水隧洞在水电和水利工程中得到广泛应用。隧洞通常沿河向布置于岸坡山体内,由于受地形条件限制,首部进口段、尾部出口临河侧向和上覆岩土均浅埋,地质条件较差,洞段坍塌冒顶时有发生。本文以巴拉电站首部枢纽导流洞前段进口局部坍塌冒顶为例,梳理事件发生发展过程,分析坍塌冒顶内外原因,总结事件处理相关经验和教训,提出类似问题的风险控制要点,可供业内同行参考。

With the continuous innovations of tunnel design and construction technology for recent decades,the ultra-large section and non-pressure transmission tunnel has been widely adopted in hydropower and water conservancy projects.The tunnel is used to be aligned along the river in bank slopes and mountains.Due to the restriction of terrain conditions,the inlet of the headworks,outlet of tail segment are shallowly buried on the river side and the overlying rock and soil,where the geological conditions are unfavorable and the collapse and roof fall occur from time to time.This article takes the partial collapse and roof fall in the inlet of the diversion tunnel of the headworks of Bala hydropower project as an example to review the entire process,analyze the the internal and external factors of the collapse and roof fall,summarize the practices and lessons of the treatment and put forward key points of risk control for similar problems,which can be used as a reference for peers in the industry.