临近基坑开挖复合地基侧向力学性状离心试验研究

发布时间：2018-08-01 17:06

【摘要】：临近基坑开挖引起复合地基CFG桩变形和内力改变,现有理论缺乏对该问题的研究。通过开展离心模型试验,对临近基坑开挖条件下,复合地基变形、CFG桩内力和变形、土压力等分布和变化规律进行深入分析。结果表明:开挖引起CFG桩弯矩增大,近基坑桩增幅明显;开挖引起桩土不同步沉降,导致CFG桩上刺入褥垫层,桩受到褥垫层的"嵌固拉结"作用,同时远基坑桩、褥垫层、加载气囊一起提供了"摩擦拉结"作用,从而在近基坑桩上出现负弯矩;而远基坑处不均匀沉降小,"嵌固拉结"作用小,且"摩擦拉结"作用是利于正弯矩产生,桩上未出现负弯矩;开挖引起支护背后土压力分为增长区和减小区两部分,在上部土体中,土体卸荷,土压力减小,而下部土体受支护挤压,土压力有所增大;开挖引起地表沉降呈指数形式,临近基坑地表沉降最大,在显著变形区域内,支护水平位移基本呈直线形式,各阶段最大水平位移均出现在支护顶端;开挖引起的CFG桩水平变形大小和范围随距基坑边距离的增大而减小。
[Abstract]:The deformation and internal force of CFG pile in composite foundation caused by the excavation of adjacent foundation pit are not studied in the present theory. Through centrifugal model test, the distribution and variation law of internal force, deformation and earth pressure of CFG pile in composite foundation are deeply analyzed under the condition of foundation pit excavation. The results show that the bending moment of CFG pile increases, and the increase of near foundation pit pile is obvious, and the pile-soil settlement caused by excavation causes CFG pile to be stuck into the cushion layer, and the pile is subjected to the action of "embedded tension" of the cushion layer, while the pile of the far foundation pit, the cushion layer of the foundation pit, and the cushion layer of the foundation pit. Loading air bags together provides a "friction pull" effect, resulting in negative bending moment on the pile near the foundation pit, while the uneven settlement in the far foundation pit is small, the "embedded tension" effect is small, and the "friction pull" effect is conducive to the generation of positive bending moment. There is no negative bending moment on the pile; the earth pressure behind the excavation is divided into two parts: the increasing area and the decreasing area. In the upper soil mass, the soil pressure decreases, but the lower soil is squeezed by the support, and the earth pressure increases. The surface settlement caused by excavation is exponential, and near the foundation pit the surface subsidence is the largest. In the area of significant deformation, the horizontal displacement of support is basically linear, and the maximum horizontal displacement of each stage appears at the top of the support. The horizontal deformation and range of CFG pile caused by excavation decrease with the increase of the distance from the side of foundation pit.
【作者单位】：山东大学基坑与深基础工程技术研究中心;山东大学土建与水利学院;
【基金】：济南市科技计划项目(201201145)
【分类号】：TU753

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