复杂地层中旋挖钻施工技术的研究与应用

Research and Application of Construction Technology of Rotary Drill in Complex Stratum

山西中南部铁路通道ZNTJ-7标段汾河特大桥工程,在含有硬塑黏土、大粒径卵石或漂石土等复杂地层的桩基施工中采用旋挖钻机成孔。通过增加泥浆浓度、增大护筒长度及采用双护筒方式、螺旋钻头和普通旋挖钻头交替使用等方法,有效解决了复杂地层中采用旋挖钻施工时钻进困难、漏浆严重、易塌孔等一系列问题,大大缩短了工期,经济效益显著。为确保单桩承载力满足要求,通过自平衡试桩法测试了3根试桩的实际承载力。结果表明,所有试桩实测承载力均大于理论承载力,说明在上述复杂地层中采用旋挖钻代替冲击钻的施工方案是经济高效的方案。

Based on the railway passage project ZNT J-7 section of Fen river super long bridge project in central and southern of Shanxi province,the borehole construction of rotary drilling rig was used in the construction of pile foundation with hard plastic clay,large diameter gravel or boulder soil in complex stratum.The methods of increasing the mud concentration,increasing the length of the protective casing and using the double protective casing,the alternate use of the spiral drill and the ordinary rotary drill were used to effectively solve a series of problems,including diff icult drilling,serious leakage and easy to collapse in the construction of rotary drill in complex stratum,which reduced the thickness of the slurry wall,increased the bearing capacity of single pile,greatly shortened the construction period and had signif icant economic benef its.In order to ensure the bearing capacity of single pile to meet the requirements,the actual bearing capacities of six pile test piles were tested by self-balanced test method.The results showed that the bearing capacities of all test piles were greater than that of the theoretical bearing capacities.It means that the construction scheme of using rotary drill to replace impact drill in the above complex stratum is an economical and eff icient scheme.