荷载传递法在湛江组结构性黏土中计算桩基沉降的研究

发布时间：2018-03-22 11:53

本文选题：湛江组结构性黏土　切入点：荷载传递函数　出处：《武汉科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：针对湛江组结构性黏土的工程地质特性,采用荷载传递法研究湛江组结构性黏土中桩土荷载传递的性状,提出一种新的考虑侧阻软化的传递函数,将这一传递函数运用到以湛江组结构性黏土为载体的桩基工程中,通过对桩在成层土中实测荷载传递函数进行非线性拟合,拟合效果良好。将拟合得到的参数采用位移协调法进行单桩沉降计算，将得到的计算结果与实测资料进行对比，结果非常的接近，证明该函数较好的反映了湛江土中桩土荷载传递机理,适合湛江地区桩基沉降计算。本文所展开的具体工作以及主要研究成果如下：（1）针对湛江黏土在受到较大荷载时出现结构性损伤及在三轴剪切试验中的应变软化现象，提出一种考虑侧阻软化的荷载传递函数，函数全面的描述了黏土随着桩土相对位移的增大强度先增大后减小最后维持在一恒定值，，较为准确的反映了土体的结构性损伤现象。（2）将提出的传递函数与5种反映侧阻软化传递函数进行比较。与其他侧阻软化传递函数相比，提出的传递函数较好的反映湛江黏土结构破坏迅速的特点，且能较好的反映黏土的残余强度。用提出的传递函数研究了土体强度分布不同及桩参数改变对沉降规律以及桩身内力的分布规律的影响。（3）结合实测单桩静载荷资料，采用此传递函数对实测点进行非线性拟合，结果表明传递函数对实测点的拟合优度较好，用拟合得到的参数采用荷载传递法进行单桩沉降计算，得到计算的P S曲线以及特定截面的轴力值，将得到结果与实测数据进行比较，数值非常接近，证明了荷载传递法能较好的计算湛江黏土中单桩沉降。（4）根据湛江黏土的工程地质情况，采用大型通用有限元分析软件ANSYS分析了成层土中单桩在竖向荷载作用下性状，建立三维桩土有限元模型，通过建立接触单元来模拟桩土之间的相互作用，得到桩身及周围土体的应力场分布和位移场分布。
[Abstract]:In view of the engineering geological characteristics of structural clay in Zhanjiang formation, the load transfer behavior of pile-soil in structural clay of Zhanjiang formation is studied by means of load transfer method, and a new transfer function considering lateral resistance softening is proposed. This transfer function is applied to pile foundation engineering with structural clay of Zhanjiang formation as the carrier, and the load transfer function of pile in layered soil is fitted by nonlinear fitting. The fitting effect is good. The parameters obtained by the method of displacement coordination are used to calculate the settlement of single pile, and the calculated results are compared with the measured data, and the results are very close to each other. It is proved that this function reflects the load transfer mechanism of pile-soil in Zhanjiang soil and is suitable for the settlement calculation of pile foundation in Zhanjiang area. The concrete work and main research results of this paper are as follows:. 1) in view of the structural damage of Zhanjiang clay under large loads and the strain softening phenomenon in triaxial shear tests, a load transfer function considering lateral resistance softening is proposed. The function fully describes that the strength of clay increases first and then decreases at a constant value with the increase of the relative displacement of the pile and soil, which accurately reflects the structural damage phenomenon of the soil. 2) the proposed transfer function is compared with five kinds of lateral resistance softening transfer functions. Compared with other lateral resistance softening transfer functions, the proposed transfer function can better reflect the rapid destruction of Zhanjiang clay structure. By using the proposed transfer function, the influence of different soil strength distribution and pile parameters on the settlement law and the distribution law of the internal force of the pile is studied. In combination with the measured static load data of single pile, this transfer function is used for nonlinear fitting of the measured point. The results show that the transfer function has a good goodness of fit for the measured point, and the parameters obtained by the fitting method are used to calculate the settlement of the single pile by load transfer method. The calculated P S curve and the axial force value of the specific section are compared with the measured data, and the values are very close. It is proved that the load transfer method can better calculate the settlement of single pile in Zhanjiang clay. According to the engineering geological conditions of Zhanjiang clay, the behavior of single pile in layered soil under vertical load is analyzed by using large scale finite element analysis software ANSYS, and a three-dimensional pile-soil finite element model is established. By establishing contact element to simulate the interaction between pile and soil, the distribution of stress field and displacement field of pile body and surrounding soil is obtained.
【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU473.1;TU433

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