φ3.8m超大直径超长钻孔桩成孔施工

Construction of Bored Holes of φ3.8 m Very Large Diameter and Very Long Bored Piles

嘉绍跨江大桥北岸水中区引桥采用φ3.8 m单桩独柱墩,共65对墩,均为摩擦桩,分左、右两幅布置。综合考虑各墩钻孔桩基础所处的水文、地质情况及施工环境因素,单桩基础采用主栈桥+施工平台的施工方案。每墩采用1台KTY4000型全液压动力头钻机成孔,研配优质PHP复合泥浆护壁,气举反循环排渣,通过1个40 m3沉渣箱循环泥浆,采用ZX-250型泥浆分离器分离小颗粒钻渣,成孔后采用JL-IUDS(B)智能超声成孔质量检测仪验孔。由于钻孔桩基础深度超过120 m,钻孔过程中多次发生漏浆现象,最终均予以及时处理。

The approach bridge of the Jiashao Bridge over the north shore water area employs the φ3.8 m single bored pile and single column piers.There are totally 65 pairs of the piers used for the bridge.The piles are all of the frictional piles that are arranged separately for the left and right bridge decks.In comprehensive consideration of the hydrologic,geologic conditions and the construction environment at the site where the pile foundations are located,the foundations are constructed by the construction scheme of main trestle plus construction platforms.At each pier,1 set of KTY4000 all hydraulic power head boring machine is used to bore the holes,the high-quality PHP compound mud is proportioned and blended and the boring slag in the holes is air-lifted.The mud is circulated in a 40 m3 sediment tank,the ZX-250 mud separator is used to separate small particle slag and the JL-IUDS（B） Intelligent Ultrasonic Drillhole Scanner is used to inspect the quality of the completed bored holes.As the bored holes are deeper than 120 m,the mud leakage problem occurrs many times in the process of boring,however,the problem is finally appropriately handled in time.