某复杂岩溶地层钻孔灌注桩成孔施工技术

Bored Piles Construction Technology in the Complex Karst Formation

某桥梁基础的地质条件复杂、岩溶强烈发育,线溶率为2.0%～86.62%,遇溶率为80%,溶洞多达7～8层,最大的溶腔高度超过60m,同时全部桥梁桩基所在位置地下溶洞连成一片,施工难度极大。为此,制定了先难后易、先远后近的施工方案,采用冲击钻进成孔与护筒跟进、气举反循环排渣的施工工艺,顺利地完成该桥基的桩基施工,取得了一些施工经验。

The geological condition of a bridge foundation is rock cave complex and intense development. The fibrinolysis rate is 2% - 86.62%. The dissolved rate is 80%. Cave is up to 7 - 8 layers. Cavity height is more than 60m, while all the bridge foundation positions of underground cave are connected into one piece. Its construction is very difficult. Therefore, it establishes the construction scheme in the first easy and far after the first, using the impact drilling hole and follow-up, casing gas lift reverse circulation construction technology, successfully completing the construction of pile foundation of the bridge, and achieving some experience in construction.