龙滩水电站左岸大坝坝后坡无盖重固结灌浆施工

Construction of non-cover-weight consolidation grouting on its back-slope of left-bank dam of Longtan Hydropower Station

龙滩水电站左岸大坝26～28号坝段303m高程以下、29～31号坝段313m高程以下坝后坡基岩固结灌浆,原设计要求先浇2m厚的先浇板,在有盖重下进行固结灌浆,然后在压力钢管安装验收后主体大坝混凝土上升。由于工期紧,后提出取消先浇板,采用无盖重固结灌浆施工工艺。固结灌浆采用普通硅酸盐水泥浆液灌注,自动记录仪记录灌浆过程,并针对灌浆中出现的浆液串冒现象,采用了简便易行的快速堵漏办法。经单位耗灰量、检查孔单位透水率、物探测试分析,成果符合灌浆规律,灌浆效果较好,质量满足设计要求,有一定的推广应用价值。

For bedrock consolidation grouting of back-slope below El303 of 26～28# dam sections and El313 of 29～31# dam sections of left-bank dam for Longtan Hydropower Station, it is required that cast about 2m thick concrete plate, then do consolidation grouting under weighted condition, and raise concrete of main dam after installation acceptance of penstock as the original design. Due to short construction period, it is proposed that not cast the plate firstly, adopt non-cover-weighted consolidation grouting construction technique to save construction period. Normal silicate cement grout pouring is adopted in consolidation grouting and the grouting process is recorded by automatic recorder. For the slurry leakage existed in the grouting, adopting fast leakage sealing method in easy way. After analysis of unit ash wastage, unit permeation rate of check hole and geophysics test result, the results conforms to grouting rule, the grouting effect is good and the quality satisfies the design requirement and also has extending value.