竖向荷载作用下群桩效应分析及数值模拟研究

发布时间：2018-02-27 15:24

本文关键词： 群桩效应 FLAC~(3D) 桩顶沉降静载试验相对位移　出处：《辽宁工程技术大学》2013年硕士论文　论文类型：学位论文

【摘要】：随着中国经济的迅猛发展,城市对群桩的需求逐年增长。为了让桩和桩间土的承载性能充分发挥,有必要对影响群桩效应的因素深入研究。以辽宁省气象局东北区域气象中心业务楼的单桩静载试验为基础,运用FLAC3D有限差分软件进行单桩和群桩的数值模拟,分析竖向荷载作用下群桩效应的影响因素对沉降、桩侧阻力、桩端阻力等方面的变化规律,并这些结论能够给今后类似地质条件下的群桩设计提供一些参考。首先,根据工程的实际背景模拟单桩静载试验,结果比较模拟数据和实测数据桩顶沉降误差为0.03mm,是实测值的6.3%。而且通过桩、土体的沉降计算接触面相对位移。粘性土极限位移为6～12mm,施加到最后一级荷载时,桩土体的相对位移未达到此值,因此,桩侧阻力荷载分担曲线呈上升趋势。其次,对同一压强和相同地质条件下的单桩和群桩地基数值模拟比较研究,得出群桩基桩的桩顶沉降值远远大于单桩桩顶沉降值,且同一承台下的各单桩桩顶沉降中,中桩沉降最大,其次是边桩沉降,角桩沉降最小。最后,通过改变桩长、桩距、承台宽度等参数对群桩地基的受力性状和变形特性进行了数值模拟。结果表明：相同竖向荷载作用下,桩长越大,沉降越小；桩距越大,沉降越小；承台宽度与桩长比例越大,沉降越小。相同荷载作用下不同桩距的群桩桩身轴力变化相似,都是上部轴力变化小,中下部变化较大。桩的轴力沿桩身长度方向先增大,然后逐渐减小,而且桩的轴力最大值是桩身顶面下来的某个深度处,并不是在桩顶面。群桩中各桩桩侧阻力是自上而下逐渐发展,且各桩桩身中下部的侧阻大,上部侧阻则明显小于下部侧阻,同时桩下部侧阻值随着桩距的增大而增大。随着上部荷载的增大,群桩基础中桩分担荷载的百分比非线性增长。
[Abstract]:With the rapid development of Chinese economy, the demand for pile groups in cities is increasing year by year. In order to give full play to the bearing capacity of piles and soil between piles, Based on the static load test of single pile in northeast regional meteorological center building of Liaoning Meteorological Bureau, the numerical simulation of single pile and pile group is carried out by using FLAC3D finite difference software. This paper analyzes the influence factors of pile group effect on settlement, pile side resistance and pile tip resistance under vertical load, and these conclusions can provide some references for pile group design under similar geological conditions in the future. First of all, according to the actual background of the project, the static load test of single pile is simulated. The results show that the settlement error of the pile top is 0.03mm compared with the measured data, which is 6.3mm of the measured value. The ultimate displacement of clay soil is 6 ~ 12 mm. When applied to the last stage load, the relative displacement of pile soil is not up to this value. Therefore, the load sharing curve of pile side resistance shows an upward trend. The numerical simulation and comparison of single pile and group pile foundation under the same pressure and same geological conditions show that the settlement value of pile top of group pile foundation is much larger than that of single pile top, and the settlement of middle pile is the largest in each single pile top settlement under the same pile cap. Secondly, the settlement of side pile is the smallest, and the settlement of angle pile is the smallest. Finally, by changing the length of pile, the distance of pile and the width of pile cap, numerical simulation is carried out on the mechanical behavior and deformation characteristic of pile group foundation. The results show that: under the same vertical load, The larger the pile length, the smaller the settlement; the larger the pile spacing, the smaller the settlement; the greater the width of the cap and the length of the pile, the smaller the settlement. The axial force of the pile first increases along the length of the pile body and then decreases gradually, and the maximum axial force of the pile is a certain depth down the top of the pile body. It is not on the top of the pile. The side resistance of each pile in the pile group develops gradually from top to bottom, and the side resistance in the middle and lower part of the pile body is large, and the side resistance in the upper pile is obviously smaller than that in the lower pile. At the same time, the lateral resistance increases with the increase of pile spacing, and the percentage of pile sharing load increases nonlinearly with the increase of upper load.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.1

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