倾斜坚硬岩层异型深基坑围护结构综合施工技术研究

Research on Comprehensive Construction Technology for Retaining Structure of Special-shaped Deep Foundation Pit in Inclined Hard Rock

  • 摘要: 针对倾斜坚硬岩石地段地下连续墙及钻孔桩施工困难、容易偏孔等难题,文章以某地铁车站深基坑围护结构施工为研究对象,通过理论研究及施工实践提出了旋挖钻机成孔+冲孔桩机成槽施工技术以及潜孔钻机+旋挖钻机成孔施工技术。结果表明:1)在坚硬岩石地段施工地下连续墙时,采用旋挖钻机间隔施工主孔,采用冲孔桩机进行副孔施工,可提高地下连续墙施工速度;2)在坚硬岩石地段施工钻孔桩难度较大,采用潜孔钻在桩位先进行梅花形钻孔,再用旋挖钻进行施工,施工速度提高明显;3)通过对旋挖钻机及潜孔钻垂直度的调整,避免了成槽成孔的倾斜,保证了在倾斜岩体中成槽成桩的垂直度;4)在倾斜坚硬岩石地段采用旋挖钻施工时,为了保证成孔成槽的垂直度,需对旋挖钻机的技术参数进行优化。

     

    Abstract: Aiming at the construction difficulties and hole deviation issuses of diaphragm retaining wall and bored pile in inclined hard rocks, the corresponding construction techniques of hole drilled by rotary drilling rig and trough constructed by piling machine, and bored hole drilled by down-the-hole drill rig + rotary drilling rig were proposed based on a theoretical and practical research, by taking the retaining structure construction of a deep foundation pit of a metro station as an example. The results show that: (1) in the construction of diaphragm retaining structure in hard rock, main holes are constructed with intervals by rotary drilling rig, and accessory holes are constructed by piling machine, which improves the construction speed of retaining structure; (2) It is difficult to construct the bored pile in the hard rock, and the quincunx bores are drilled by down-the-hole drill rig and then followed by rotary drilling, which greatly increases the construction speed; (3) by adjusting the perpendicularity of the rotary drilling rig and the down-the -hole drill rig, the inclination of troughs and holes is avoided, guaranteeing the perpen? dicularity in the inclined rock mass; (4) the technical parameters of rotary drilling rig should be optimized to guarantee the perpendicularity during the rotary drilling construction in inclined hard rocks.

     

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