向家坝水电站大坝不良地质坝基防渗施工技术

Technology of Impermeable System Construction of Dam Foundation with Unfavorable Geological Conditions,Xiangjiaba Hydropower Project

向家坝水电站坝基岩体透水性较好,地下水丰富,且存在破碎带、软弱夹层等不良地质地层。渗控体系为防渗帷幕和坝基防渗墙联合防渗形式,防渗墙布置在重力坝坝基廊道内施工。廊道内防渗墙施工中着重研究实施了地下水控制、设备选型和出碴等技术,解决了施工难题。在不良地层中施工帷幕时,采用高喷置换和其它工艺,解决了地基中塌孔、卡孔、灌浆失水等难题,保证了渗控体系的施工质量。

The dam foundation rockmass of Xiangjiaba Hydropower Project is with good permeability.Here the ground water is rich.And stratum with the unfavorable geological conditions is available such as fractured zone, soft/weak interlayer, etc.The seepage control system is the combination of grouting curtain and cutoff wall on dam foundation.The cutoff wall is arranged and built in the gallery of the gravity dam foundation.During the construction of the cutoff wall in the gallery, control of ground water, type selection of equipment and debris mucking-out, etc are studied and executed especially.According, the construction difficulties are eliminated.When the grouting curtain in the stratum with the unfavorable geological conditions is constructed , the jet spraying and replacement , and other techniques are applied to avoid hole collapse, choked and grout losing, etc to assure the construction quality of the seepage control system.