三峡工程二期围堰混凝土防渗墙的施工

Construction of concrete impervious wall for the second phase cofferdam in the Three Gorges Project

三峡工程二期围堰混凝土防渗墙是围堰工程成败的关键。在施工中采用了多种新设备、新工艺、新材料， 主要有： ①ＢＣ３０ 型液压铣槽机， 机械式抓斗， 冲击反循环钻机， 全液压工程钻机， 超声波测井仪； ②“两钻一抓”法、“铣砸爆”法、“铣抓钻结合”法成槽工艺， “铣削”法、“双反弧接头槽”法槽段连接方法和深水电磁铁打捞技术； ③柔性材料、塑性混凝土和膨润土等新材料。施工中还突破了松散漏失地层处理， 陡坡、块球体和硬岩钻进， 灌浆管埋设等技术难关。单元工程合格率１００％ ， 优良率８０％ 以上。三峡工程二期围堰为我国防渗墙施工开创了新局面， 积累了丰富的经验。

The concrete impervious wall for the second phase cofferdam in the Three Gorges Project is the key to the cofferdam. In the construction, many new equipment, new technologies and new materials have been adopted. Those new construction tools are as follows: BC 30 hydraulic groove milling machine, mechanical clamshell, percussion anti circulation drill, full hydraulic engineering drill and ultrasonic logger. The adopted new technologies are the groove formed technologies such as “two drillings and one clam' method,“milling tamping blasting' method, “milling claming drilling' method; groove section connection technologies such as “milling cutting' method and 'double ogee junction groove' method; and deep water electromagnet salvage technology. The following new materials have been used: flexible materials, plastic concrete and bentonite. In the construction, some technical difficulties have been overcome, such as treatment of loose and leakage layer, drilling in steep slope, blocky sphere and hard rock, and burying the grouting pipe, etc. For the unit engineering, one hundred percent the works are up to standard and more than 80% of them have good quality. The second phase cofferdam in the Three Gorges Project has initiated a new situation of the construction of impervious wall in China and has accumulated rich experience.