CFG桩复合地基抗震性能数值分析

发布时间：2018-04-27 21:01

本文选题：CFG桩 + 复合地基　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：作为现代高层建筑软土地基处理的主要手段,CFG桩复合地基以其优越的地基加固性能在我国得到了广泛的应用。同时,我国作为地震高发的国家,城市的高速发展深受地震自然灾害的制约。因此,对CFG桩复合地基抗震性能的深入研究具有深远的意义。本文通过对CFG桩复合地基的承载机理及破坏机理的分析,利用LS-DYNA有限元动力学分析软件,对CFG桩复合地基抗震性能的动力学特性进行了数值分析研究,同时,进一步研究了CFG桩复合地基设计参数对CFG桩复合地基抗震性能的影响。本文通过对CFG桩复合地基抗震性能的分析研究,获得主要成果如下:1)在地震荷载作用下,CFG桩复合地基破坏的判别主要是通过CFG桩复合地基桩体的位移、应力进行判断。当桩体截面拉应力在桩体截面抗拉强度范围内,桩顶水平位移在水平位移容许值范围内时,桩体不会产生破坏,复合地基处于安全状态。2)本文建立了地震荷载作用下CFG桩复合地基动力学数值模型。对地震作用下CFG桩复合地基不同位置桩体及桩间土的水平及竖向加速度、位移、应力进行了对比分析,得到了桩体水平及竖向加速度、位移的变化规律,同时,得到了桩体及桩间土水平及竖向应力变化规律:(1)在地震荷载作用下,CFG桩复合地基桩体的水平加速度由桩顶至底部随深度的增加先减小后增大;(2)水平位移呈现随深度的增加不断减小的规律;(3)水平应力随深度的增加先增大后减小,同时,边桩较中心桩的水平应力更大;(4)边桩产生的竖向加速度比中心桩竖向加速度大;(5)边桩竖向位移远大于中心桩的竖向位移;(6)桩体竖向应力随深度的增加先增大后减小。3)将不同的设计参数(桩径、桩长、桩间距)作为变量参数,通过对比分析,得到了各设计参数对CFG桩复合地基抗震性能的影响:(1)增大桩体直径可以减小产生的加速度、变形及桩体的水平应力,提高复合地基的抗震性能。但是,这会增大桩体的竖向应力易导致桩体的破坏;(2)增加桩体长度可以减小复合地基受地震波作用所产生的加速度、变形及桩体竖向应力,提高复合地基的抗震性能。但是,这会增大桩体的水平应力导致桩体的破坏;(3)增大桩间距对桩体及桩间土地震作用下所产生的加速度及位移影响很小,同时其应力呈减小的趋势。
[Abstract]:CFG pile composite foundation, as the main means of soft soil foundation treatment in modern high-rise buildings, has been widely used in China because of its excellent foundation strengthening performance. At the same time, as a country with high incidence of earthquakes, the rapid development of cities is restricted by earthquake natural disasters. Therefore, it is of great significance to study the seismic behavior of CFG pile composite foundation. Based on the analysis of bearing mechanism and failure mechanism of CFG pile composite foundation, the dynamic characteristics of seismic behavior of CFG pile composite foundation are studied numerically by using LS-DYNA finite element dynamic analysis software. The influence of the design parameters of CFG pile composite foundation on the seismic behavior of CFG pile composite foundation is further studied. Based on the analysis of the seismic behavior of the CFG pile composite foundation, the main results are as follows: 1) the main result of judging the damage of the CFG pile composite foundation under the earthquake load is mainly through the displacement and stress of the pile body of the CFG pile composite foundation. When the tensile stress of the pile section is in the range of tensile strength of the pile section and the horizontal displacement of the top of the pile is within the allowable range of the horizontal displacement, the pile body will not be destroyed. In this paper, the dynamic numerical model of CFG pile composite foundation under earthquake load is established. The horizontal and vertical acceleration, displacement and stress of pile and soil in different positions of CFG pile composite foundation under seismic action are compared and analyzed, and the variation law of horizontal and vertical acceleration and displacement of pile body are obtained, at the same time, The rule of horizontal and vertical stress variation of pile and soil between piles is obtained. (1) the horizontal acceleration of CFG pile composite foundation under earthquake load decreases first with the increase of pile depth and then increases with depth.) the horizontal displacement of CFG pile composite foundation decreases with depth and then increases with depth. The horizontal stress increases first and then decreases with the increase of depth. At the same time, Vertical displacement of side pile is much greater than that of central pile.) Vertical stress of side pile increases first and then decreases with the increase of depth. (5) Vertical displacement of side pile is much greater than that of center pile (4) the vertical acceleration of edge pile is greater than that of center pile (5) the vertical displacement of side pile is much greater than that of center pile (4) the vertical stress of side pile increases first and then decreases with the increase of depth. Small. 3) will be different design parameters (pile diameter, By comparing and analyzing the influence of design parameters on seismic behavior of CFG pile composite foundation, the influence of different design parameters on seismic behavior of CFG pile composite foundation is obtained. The increase of pile diameter can reduce the acceleration, deformation and horizontal stress of pile body. Improve the seismic performance of composite foundation. However, this will increase the vertical stress of the pile and lead to the failure of the pile. Increasing the length of the pile can reduce the acceleration, deformation and vertical stress of the composite foundation caused by seismic waves, and improve the seismic performance of the composite foundation. However, this will increase the horizontal stress of the pile and lead to the failure of the pile. (3) increasing the spacing of the pile has little effect on the acceleration and displacement of the pile and the soil between the piles, and its stress tends to decrease.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU470;TU435

【参考文献】