DX旋挖挤扩灌注桩群桩数值分析研究

通过数值计算软件FLAC3D对DX旋挖挤扩灌注桩（简称DX桩）群桩的承载性状和桩周土体的沉降规律进行了研究。分析了桩间距、承力盘布置对群桩极限承载力和沉降控制能力的影响，并比较了6根基桩的DX群桩和8根基桩的直桩群桩的极限承载力。研究结果表明：DX群桩的基桩具有DX单桩的受力性状。承力盘下方土体位移大于承力盘上方土体位移，盘腔上部出现临空面。3D(D为盘径)桩间距的承载力和沉降控制能力最佳。同一地层内，承力盘布置方式（平行、错开布置）对DX群桩的承载力影响甚微。6根基桩的DX群桩的极限承载力是8根基桩的直

Numerical analysis for casted in place DX pile groups

DX pile group is simulated by numerical analysis software FLAC3D to study the mechanics behavior and the pile soil settlement rules. Analysis of the influence of pile spacing and plate arrangement to ultimate bearing capacity and settlement control, and comparison of the ultimate bearing capacity of straight pile group with 8 piles with the DX pile group with 6 piles are done. The result indicates that the pile of DX pile group has the same bearing mechanism with the DX single pile. The displacement of the soil below the bearing plate is greater than that above the bearing plate, which leads to the free surface of the upper cavity. 3D (D is the diameter of the bell) pile spacing can perform the best bearing capacity and settlement control. Within the same stratum, bell arrangement (staggered arrangement and parallel arrangement) has little effect to the bearing capacity of DX pile group. The ultimate bearing capacity of DX pile group with 6 piles is as 1.27 times as the straight pile group with 8 piles. With DX pile group, we can not only effectively control the settlement, but also reduce the number of piles and save the project cost. These research results provide valuable basis for the rational design of pile groups of this type.