基于软土微孔隙特征变化规律的固结模型及计算理论

发布时间：2018-03-07 02:11

本文选题：软土　切入点：微孔隙特征　出处：《华南理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：非线性固结压缩是软土固有的复杂特性之一。历经六十多年的发展,非线性固结理论已经取得比较丰富的成果,但大多数都是从宏观角度研究软土渗透固结性状,关于软土非线性固结模型与固结系数模型的选定及其参数的确定等问题仍然是困扰固结理论在软土工程实践应用和发展的难题。在充分认识软土微观变化规律对固结特性影响的基础上,建立能反映软土实际受力固结变形的固结模型,进一步实现数值分析并应用于岩土工程实践中是一项重要而紧迫的工作。本文通过室内试样和理论分析,对软土固结模型及计算理论进一步开展了较为深入的研究。主要内容包括:(1)总结和分析了当前国内外关于软土微观结构特征及工程特性研究成果,介绍国内外对软土固结模型的探索研究和固结模型的适用范围。(2)以珠江三角洲重塑软土为研究对象,进行固结试验及渗透试验。基于试验结果,总结出适用于珠江三角洲正常固结软土的非线性固结模型及固结系数模型。软土固结模型固结系数由天然部分和固结变化部分组成,后者可表达为与固结压力的关系。(3)基于e-lnp模型和大应变条件,联立土体单元平衡方程、几何变形方程及渗流连续方程,建立了适用于软土的一维非线性固结模型及固结系数计算模型,并将一维固结方程推广到二维、三维情况下的固结模型。基于软土微孔隙特征变化规律的固结模型满足变形协调条件。(4)利用有限差法隐式差分格式解一维固结方程,利用有限差分法交替方向隐式格式(ADI格式)求解二维固结方程、轴对称固结方程及三维固结方程,用Matlab软件编制差分法求解程序,差分程序得到的数值解与Terzaghi一维固结精确解及Terzaghi-Rendulic固结方程精确解结果良好吻合,验证差分格式求解的有效性及准确性。(5)对一维固结情况、二维固结情况、双层地基及砂井问题进行理论计算。数值计算结果表明:基于软土微孔隙特征变化规律的固结模型超静孔隙水压力消散速度明显慢于固结系数为常数的Terzaghi固结模型、Terzaghi-Rendulic固结方程及Biot固结模型,更能正确反映一维或多维情况下单层及多层地基孔隙水消散过程。与软土固结试验数值相比较,WG固结模型理论更加符合真实情况。
[Abstract]:Nonlinear consolidation and compression is one of the inherent complex characteristics of soft soil. After more than 60 years of development, the theory of nonlinear consolidation has made a lot of achievements, but most of them are from the macro perspective to study the properties of soft soil osmotic consolidation. The selection of nonlinear consolidation model and coefficient model of soft soil and the determination of its parameters are still difficult problems for the application and development of consolidation theory in soft soil engineering. Based on the effect of consolidation characteristics, It is an important and urgent work to establish a consolidation model which can reflect the actual stress and deformation of soft soil, and to further realize numerical analysis and its application in geotechnical engineering. The consolidation model and calculation theory of soft soil are further studied. The main contents include: 1) summarize and analyze the research results of microstructure and engineering characteristics of soft soil at home and abroad. This paper introduces the exploration and research of soft soil consolidation model at home and abroad and the applicable scope of consolidation model. (2) taking the remolded soft soil in the Pearl River Delta as the research object, the consolidation test and permeation test are carried out. The nonlinear consolidation model and the consolidation coefficient model for the normal consolidation soft soil in the Pearl River Delta are summarized. The consolidation coefficient of the soft soil consolidation model consists of the natural part and the consolidation variation part. The latter can be expressed as the relationship with consolidation pressure. (3) based on e-lnp model and large strain condition, the simultaneous soil element equilibrium equation, geometric deformation equation and seepage continuity equation are established. The one-dimensional nonlinear consolidation model and the calculation model of consolidation coefficient for soft soil are established, and the one-dimensional consolidation equation is extended to two-dimensional consolidation equation. The consolidation model based on the variation of micropore characteristics of soft soil satisfies the deformation coordination condition. (4) the finite difference implicit difference scheme is used to solve the one-dimensional consolidation equation. The finite difference method is used to solve two dimensional consolidation equation, axisymmetric consolidation equation and three dimensional consolidation equation by alternating direction implicit scheme (ADI). The program of difference method is compiled with Matlab software. The numerical results obtained by the difference program are in good agreement with the results of the Terzaghi one-dimensional consolidation exact solution and the Terzaghi-Rendulic consolidation equation, which verify the validity and accuracy of the difference scheme for one-dimensional consolidation and two-dimensional consolidation. The numerical results show that the consolidation model based on the rule of variation of micropore characteristics in soft soil is obviously slower than the Terzaghi consolidation model with constant consolidation coefficient in excess pore pressure dissipation rate. Terzaghi-Rendulic consolidation equation and Biot consolidation model, Compared with the consolidation test of soft soil, the WG consolidation model theory is more suitable for the real situation.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43

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