3d嵌岩桩界面工作特性分析
发布时间：2018-07-22 14:48
【摘要】：嵌岩桩作为桩基基础已经广泛应用于高层建筑、大型桥梁、重型厂房等重点工程中,关于其工作机理的研究颇多,其破坏形式也有多种。例如:嵌岩段桩端岩石剪切与压屈破坏模式、整体剪切破坏形式、桩岩界面破坏模式等。其应用的理论模型也各有不同,并得出了不同的结果。本文假设桩体及岩体具有足够的强度,嵌岩桩的破坏为桩岩界面破坏,采用室内模型试验的方法对嵌岩桩的工作机理展开研究。为达到试验数据能够反映实际工程的目的,模型试验的制作工序模拟现场实际工程桩的成桩工序,采用GH-200电子万能试验机、WDW-E200D负荷传感器、DH-3814-4静态应变测试仪、百分表分别对桩体加载、位移及应变进行测试并利用力学关系式求出轴力和摩阻力的变化关系。制作了两个试件分别进行一次加载和反复加载试验进行对比,根据整理所得数据得到如下试验成果:1)通过试验发现桩基在一次加载过程中,荷载-位移曲线可以分为三个不同的变形阶段:第Ⅰ阶段属于弹性阶段;第Ⅱ阶段属于屈服阶段;第Ⅲ阶段属于残余变形阶段。这三个阶段反应了桩体在整个加载过程中桩顶位移、桩底位移、桩体压缩量与加载之间的变化关系;2)在本实验一次加载和反复加载过程中,桩身嵌岩段轴力均是自上而下逐渐变小,而且在卸载后存在着部分残余变形,不可完全回复;3)在一次加载和反复加载到极限荷载时,桩土界面摩阻力小,桩岩界面摩阻力大。在模拟土体和模拟岩体交界面处摩阻力变化最快,桩体在这个截面的摩阻力为所有截面中最大;4)一次加载和反复加载均反映出一个共同的问题:随着桩顶荷载值的变大,力是逐步传至桩底的,桩身各截面处的摩阻力并不是同步发挥作用的。桩与土体之间摩阻力先发挥至最佳,随后桩与岩体之间的摩阻力发挥至最佳,当桩岩界面即将发生破坏时,桩体的承载力就达到了极值。
[Abstract]:Rock socketed pile as a pile foundation has been widely used in high-rise buildings, large bridges, heavy plant and other key projects. There are a lot of research on its working mechanism and many kinds of failure forms. For example: rock shear and buckling failure mode, integral shear failure mode, pile rock interface failure mode and so on. The applied theoretical models are different, and different results are obtained. In this paper, it is assumed that the pile body and rock mass have sufficient strength, and the failure of rock-socketed pile is the failure of pile-rock interface. The working mechanism of rock-socketed pile is studied by the method of laboratory model test. In order to achieve the purpose that the test data can reflect the actual project, the production procedure of the model test simulates the piling procedure of the actual engineering pile on the spot, and the static strain tester DH-3814-4 is used in the WDW-E200D load sensor with GH-200 electronic universal testing machine. The load displacement and strain of pile are measured by the dial table and the relationship between axial force and friction resistance is obtained by using the mechanical relation. Two specimens were made to carry out one loading test and the repeated loading test respectively. According to the data collected, the following experimental results were obtained: 1) the pile foundation was found to be in the process of one loading. The load-displacement curve can be divided into three different deformation stages: the first stage belongs to the elastic stage, the second stage belongs to the yield stage, and the third stage belongs to the residual deformation stage. These three stages reflect the relationship between pile top displacement, pile bottom displacement, pile compression and loading during the whole loading process. The axial force of the rock-embedded segment of the pile is gradually reduced from the top to the bottom, and there is some residual deformation after unloading, which can not be fully recovered. 3) when the pile is loaded and repeatedly loaded to the limit load, the friction resistance of the pile-soil interface is small and the frictional resistance of the pile-rock interface is large. At the interface between the simulated soil and the simulated rock mass, the friction resistance of the pile is the largest in all sections. The single loading and repeated loading all reflect a common problem: with the increase of the pile top load, The force is gradually transmitted to the bottom of the pile, and the friction at each cross section of the pile does not act synchronously. The friction resistance between pile and soil is the best, and then the friction between pile and rock is the best. When the interface of pile and rock is about to be destroyed, the bearing capacity of pile reaches the extreme value.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1
本文编号：2137811
[Abstract]:Rock socketed pile as a pile foundation has been widely used in high-rise buildings, large bridges, heavy plant and other key projects. There are a lot of research on its working mechanism and many kinds of failure forms. For example: rock shear and buckling failure mode, integral shear failure mode, pile rock interface failure mode and so on. The applied theoretical models are different, and different results are obtained. In this paper, it is assumed that the pile body and rock mass have sufficient strength, and the failure of rock-socketed pile is the failure of pile-rock interface. The working mechanism of rock-socketed pile is studied by the method of laboratory model test. In order to achieve the purpose that the test data can reflect the actual project, the production procedure of the model test simulates the piling procedure of the actual engineering pile on the spot, and the static strain tester DH-3814-4 is used in the WDW-E200D load sensor with GH-200 electronic universal testing machine. The load displacement and strain of pile are measured by the dial table and the relationship between axial force and friction resistance is obtained by using the mechanical relation. Two specimens were made to carry out one loading test and the repeated loading test respectively. According to the data collected, the following experimental results were obtained: 1) the pile foundation was found to be in the process of one loading. The load-displacement curve can be divided into three different deformation stages: the first stage belongs to the elastic stage, the second stage belongs to the yield stage, and the third stage belongs to the residual deformation stage. These three stages reflect the relationship between pile top displacement, pile bottom displacement, pile compression and loading during the whole loading process. The axial force of the rock-embedded segment of the pile is gradually reduced from the top to the bottom, and there is some residual deformation after unloading, which can not be fully recovered. 3) when the pile is loaded and repeatedly loaded to the limit load, the friction resistance of the pile-soil interface is small and the frictional resistance of the pile-rock interface is large. At the interface between the simulated soil and the simulated rock mass, the friction resistance of the pile is the largest in all sections. The single loading and repeated loading all reflect a common problem: with the increase of the pile top load, The force is gradually transmitted to the bottom of the pile, and the friction at each cross section of the pile does not act synchronously. The friction resistance between pile and soil is the best, and then the friction between pile and rock is the best. When the interface of pile and rock is about to be destroyed, the bearing capacity of pile reaches the extreme value.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1
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