论文部分内容阅读
对2个初始直径为0.76m、桩长为2.79m和5.10m的夯扩碎石桩群桩进行载荷试验,并采用三维拉格朗日有限差分程序建立数值模型,模拟其夯扩和载荷试验分级加载过程,并分析了桩土应力比、群桩效应和桩间土单元的应力路径。结果表明:数值分析很好地模拟了夯扩碎石群桩的夯扩过程,群桩夯扩成桩后最大垂直位移位于桩间土中心且表现为地面隆起;计算和实测的荷载-沉降曲线基本一致;2个不同桩长的夯扩碎石桩群桩在各级荷载下的桩土应力比都比较接近,其值在3.8～6.5之间;群桩效应跟桩长与承台宽度比L/Bc相关,群桩负效应随L/Bc的增大而减弱;2个不同桩长的群桩桩间土单元在夯扩过程中其水平应力大于垂直应力,单元应力处于临界破坏状态;夯扩作用在桩间土中产生预应力,提高了土体刚度和夯扩碎石桩的承载能力,靠近桩端的土体单元预应力受桩端夯扩效应影响而增大。
Two load-bearing tests were conducted on two rammed pile groups with an initial diameter of 0.76m and a pile length of 2.79m and 5.10m respectively. The numerical model was established by using the three-dimensional Lagrange finite difference program to simulate the rammer expansion and load test Grading loading process, and analyzed the pile-soil stress ratio, pile group effect and the stress path of soil between piles. The results show that: numerical analysis well simulates the ramming expansion process of rammed expanded gravel piles. The maximum vertical displacement of rammed expanded pile is located at the center of soil between piles and shows uplift. The calculated and measured load-settlement curve The pile-soil stress ratio of two different pile-length rammed-expanded gravel pile groups is relatively close to each other under the loads of all levels, and its value is between 3.8 and 6.5; L / Bc. The negative effect of pile group decreases with the increase of L / Bc. The horizontal stress of two soil groups with different pile lengths in pile-grouting process is larger than the vertical stress and the unit stress is in the critical failure state. Ramming expansion effect prestressed in the soil between the piles to improve soil stiffness and carrying capacity of tampered gravel piles, soil element near the pile tip prestressed by the end of the pile expansion effect of expansion and increase.