可回收桩锚变形影响因素模型试验与数值模拟

Model test and numerical simulation of deformation influencing factors of recoverable pile anchor

通过室内可回收桩锚支护基坑模型试验及MIDAS GTS NX有限元软件,探究基坑开挖与回填阶段锚杆回收对基坑变形的影响。通过改变锚杆倾角、竖向间距、桩长、桩间距等参数,揭示桩体水平位移、地表沉降及桩身弯矩的变化规律。结果表明:可回收桩锚支护结构的支护效果与传统桩锚支护一致,地表沉降曲线呈凹槽型,支护结构水平位移以圆弧形式向坑内扩展破坏;在回填阶段,锚杆的失效回收是造成支护结构位移增长的主要因素,其中又以上层锚杆的影响最为突出;在使用可回收桩锚支护的基坑中,可回收锚杆的竖向间距取值为6D、倾角为10°~30°时,支护效果较为理想,也可以通过适当增加桩长与锚杆层数来控制基坑变形。

In this work,the effects of anchor recovery on foundation pit deformation during excavation and backfilling were explored based on the model test of foundation pit supported by recoverable pile and anchor and MIDAS GTS NX finite element software.By changing the parameters such as anchor angle,vertical spacing,pile length,and pile spacing,the variation laws of horizontal displacement,surface settlement,and bending moment of pile body were revealed.The results show that the supporting effect of the recoverable pile-anchor supporting structure is the same as that of the traditional pile-anchor supporting structure,the surface settlement curve is groove-shaped,and the horizontal displacement of the supporting structure extends into the pit in the form of arc.In the backfill stage,the failure recovery of anchor is the main factor causing the displacement growth of supporting structure,and the influence of upper anchor is the most prominent.In the foundation pit supported by recoverable piles and anchors,the vertical spacing of recoverable anchors is 6D,and the supporting effect is ideal when the angle lies in the range of 10°-30°.The deformation of foundation pit can also be controlled by appropriately increasing the pile length and the number of anchor layers.