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钻孔桩基础在我国的桥梁中用得较多.但在纯砂地层用得却较少,原因是其施工难度较大.我们在318国道的黄陂滠水公路大桥的施工中,采用片石泥浆护壁冲击成孔的办法,成功地在纯砂层中施作了桩基础,本文对其具体做法作一介绍.1 工程概况滠水大桥桥位处的地质情况为:覆盖层为第四系粘土及冲积砂层,厚15～20m,基岩为元古界红安群磨盘组上绿帘石英千枚岩,取样强度为20MPa.桥位为采砂区,由于长年取砂,覆盖层的粘土已被除尽,所剩全部为中细砂,含泥量仅为1%,渗水系数为18～20m/d.滠水发源于大别山汇于长江,桥址常年有水,枯水期(11月至次年3月)水深1～9m.桥墩(台)基础设计为直径1.5m的钻孔嵌岩桩,共68根,嵌岩深度1～4m.
Bored pile foundation used in our country bridge more, but the use of pure sand formation is less, because of its construction more difficult.We 318 in the construction of the Huangpi River waterway bridge, the use of stone slurry Wall impact into the hole approach, the successful implementation of the pile foundation in the pure sand layer, this article to make an introduction to its specific practices .1 Engineering Overview Lushui Bridge site geological conditions are as follows: the cover of Quaternary clay And alluvial sand, thickness of 15 ~ 20m, the bedrock for the Proterozoic Hongan group Mopan Formation green Cui phyllite, sampling intensity of 20MPa. Bridge site for the sand mining area, because of sand for many years, the cover layer Clay has been removed, leaving all the fine sand, clay content of only 1%, water seepage coefficient of 18 ~ 20m / d. Originated in the Dabieshan Huiyuan in the Yangtze River, the bridge site perennial water, dry season (November To March next year) depth of 1 ~ 9m. The foundation of the pier (station) is designed as a drill-embedded rock-socketed pile with a diameter of 1.5m, a total of 68, embedded rock depth of 1 ~ 4m.