高速铁路复杂岩溶环境下超长钻孔桩施工技术

新建潍坊至莱西铁路大白村特大桥大理岩一般呈层状分布或以夹层、透镜体产于吕梁期侵入岩斜长角闪岩中,地质特征较为复杂。受构造作用、地层结构及地下水等影响,大理岩岩溶强烈发育,呈现出竖向串珠状、横向强连通性的特征,尤以59#墩最为显著。该墩钻孔灌注桩设计为75.5m,属超长岩溶桩,成孔困难,综合比较后采取冲击钻成孔,长钢护筒、溶洞反复回填冲击、泥浆护壁等综合施工方法,保证了成孔质量及施工进度。

The marble of Dabaicun Bridge on the newly-built Weifang-Laixi Railway is generally distributed in layers or as intercalated and lenticular bodies in the amphibolites of intrusive rocks of LüliangStage,and its geological characteristics are rather complicated.Under the influence of tectonics,stratigraphic structure and groundwater,the karst of marble was strongly developed,showing the characteristics of vertical bead shape and strong lateral connectivity,especially the pier#59.The bored cast-in-place pile of this pier is designed to be 75.5 m,which belongs to super long karst pile and is difficult to be drilled into hole.After comprehensive comparison,comprehensive construction methods are adopted,such as drilling hole with wallop,back filling impact with long steel tube and karst cave repeatedly,protecting wall with mud,etc.The drilling quality and construction progress are ensured.