水平预裂爆破在基础保护层开挖中的应用

Foundation Cover Excavation by Presplit-Blasting Horizontally

泄洪与挡水大坝 (包括左导墙 )为长江三峡水利枢纽主体建筑物之一 ,为一等工程、 级建筑物 ,建基面高程由 - 8.0 0 m～ 5 0 .0 0 m,建基面面积为 8.8万 m2 ,土石方开挖工程量 416万 m3 (其中石方开挖工程量 2 15万 m3 ) ,具有钻爆工作量大 ,开挖强度高 ,地质条件复杂 ,建基面开挖质量要求高的特点。鉴于以上特点 ,采用传统的保护层分层爆破开挖法无法满足建基面基础开挖工期和质量要求 ,因此三峡二期主体工程建基面保护层开挖采用水平预裂爆破辅以垂直浅孔梯段爆破法。实践证明 ,该施工方案工艺先进 ,参数确定合理 ,施工效率高 。

The spillway and water retaining sections including the left guide wall are among the main structures of the Three Gorges Project. They are all the grade I works and the first class structures, with an area of 88 000 m 2 on the construction foundation El. 8.00 m - 50.00 m. The earth rock excavation was up to 4 160 000 m 3 including 2 150 000 m 3 of rock, characterized by heavy drilling and blasting workload, high excavation rate and high excavation quality requirement under the complex geological conditions. The traditional cover excavation by blasting in layers could not meet the requirements for excavation schedule and quality. Therefore, the foundation cover for thesecond phase main works was excavated by presplit blasting horizontally, supported with a method of bench shooting in short holes. It has proved practically that the construction program, with advanced procedures, rational parameters and high construction efficiency, took a decisive effect in completion of the second phase main works on schedule and with quality guaranteed.