基于LSMPS算法的软土固结—蠕变模型参数识别研究
发布时间：2018-07-20 13:44
【摘要】：软土路基在受到外界荷载作用过程中,先期是由孔隙水排出产生的固结变形,随着土体骨架被压密,在荷载的作用下会产生与时间有关的形变—蠕变。如何确定软土路基最终沉降量及探讨软土固结-蠕变机理成为软土加固与稳定的重要研究方向。本文以土力学理论、经典固结理论、蠕变模型理论为基础,通过开展室内盘锦滨海公路路基软土三轴固结蠕变剪切试验获取软土固结蠕变轴向变形、孔隙水压力等数据,提出了二阶广义Kelvin固结-蠕变模型,利用基于搜索模式的最小二乘算法一LSMPS (Least Square Method based on Pattern Search)对二阶广义的Kelvin模型的参数进行搜索与优化,并且以工程仿真为依托,进行软土路基固结-蠕变机理工程仿真分析。具体研究成果如下：(1)开展了不同围压下软土三轴固结-蠕变试验,获得了分级加载下软土试样在不同偏应力水平下的孔隙水压与时间的关系以及竖向变形随时间发展的曲线,利用陈氏加载法将分级加载曲线转化为“分别加载”曲线,利用同一时刻应力应变关系将“分别加载”曲线转化为应力应变等时曲线。通过试验研究发现采用衰减的指数类型函数可以描述软土的变形-时间之间的函数关系,而广义的Kelvin蠕变模型本构方程和衰减的指数函数之间具有高度的相似特征,因此可以使用高阶广义的Kelvin模型本构方程作为描述软土试样的固结-蠕变特征的本构方程。(2)利用LSMPS算法对简化的二阶广义的Kelvin模型的参数进行模式化搜索,对模型的参数通过迭代的方法进行搜索和优化,研究发现,简化的广义Kelvin模型方程是各模型参数的单调函数,在理论上可以确定该方程在全局上存在唯一的极值而不会使模式化搜索陷入局部最优。对比通过LSMPS算法确定的广义Kelvin模型方程与试验数据之间的相似度,相关性系数均在0.99以上,因此,使用该方法所确定参数的模型在描述软土固结-蠕变特征方面效果较好。(3)分析了软土Biot固结方程,考虑软土发生蠕变时产生的节点附加应力对Biot固结方程的影响,确定了软土固结-蠕变共同作用时的统一有限元模型：利用ADlNA8.4提供的强大工程仿真平台将山LSMPS确定的模型参数转化为ADINA中提供的专门用于模拟岩土蠕变的Lubby2本构模型各参数,使之模拟软土路基的地应力、孔隙水压力、固结-蠕变变形在软土路基内部的分布状况。以上研究成果为进一步丰富和完善软土固结-蠕变变形特征、有效控制软土路基的竖向沉降以及合理设计软土路基工程的加固稳定方案提供了理论依据。
[Abstract]:In the process of external load, soft soil subgrade is the consolidation deformation produced by the discharge of pore water. With the compaction of the soil skeleton, the deformation and creep associated with time will be produced under the action of load. How to determine the final settlement of the soft soil subgrade and to discuss the mechanism of soft soil consolidation creep are important for the reinforcement and stability of soft soil. In this paper, based on soil mechanics theory, classical consolidation theory and creep model theory, by carrying out the three axis consolidation creep shear test of soft soil in Panjin coastal road subgrade, the axial deformation of consolidation creep, pore water pressure and so on are obtained, and the two order Kelvin consolidation creep model is proposed, which is based on the search model. The least square algorithm LSMPS (Least Square Method based on Pattern Search) searches and optimizes the parameters of Nikai Hiroyoshi's Kelvin model, and based on the engineering simulation, the consolidation and creep mechanism engineering simulation analysis of soft soil subgrade is carried out. The concrete research results are as follows: (1) the consolidation and creep of three axis soft soil under different confining pressure has been carried out. The relationship between the pore water pressure and the time of the soft soil specimen under different stress levels under the graded loading and the curve of the vertical deformation along with the time are obtained. By using the Chen's loading method, the graded loading curve is transformed into "respectively loading" curve, and the "separately loaded" curve is transformed into the corresponding stress stress stress relationship. It is found that the exponential type function of attenuation can be used to describe the relationship between the deformation and time of soft soil, while the generalized Kelvin creep model is highly similar to the exponential function of the attenuation exponent, so it can be used as the high order generalized Kelvin model constitutive equation. The constitutive equation describing the consolidation and creep characteristics of soft soil samples. (2) using the LSMPS algorithm to model the simplified Nikai Hiroyoshi Kelvin model parameters, search and optimize the parameters of the model by iterative method. It is found that the simplified generalized Kelvin model equation is the monotone function of the parameters of each model. It can be determined that the equation has a unique extreme value on the global level and does not make the pattern search fall into the local optimal. The similarity between the generalized Kelvin model equation and the experimental data determined by the LSMPS algorithm is more than 0.99. Therefore, the model of the parameters determined by this method is used to describe the consolidation and creep of the soft soil. The effect is good. (3) analysis of the soft soil Biot consolidation equation, considering the effect of the additional stress on the Biot consolidation equation caused by the creep of the soft soil, and determining the unified finite element model of the joint action of the consolidation and creep of soft soil: using the powerful engineering simulation platform provided by ADlNA8.4 to transform the model parameters determined by mountain LSMPS into A The parameters of the Lubby2 constitutive model, which are specially used to simulate the creep of rock and soil, are provided in DINA to simulate the distribution of ground stress, pore water pressure and consolidation creep deformation in soft soil subgrade. The above research results can further enrich and improve the consolidation and creep deformation characteristics of soft soil, and effectively control the vertical subsidence of soft soil subgrade. It provides a theoretical basis for reducing and rationally designing reinforcement and stabilization schemes for soft soil roadbed projects.
【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】：2015
【分类号】：U416.16
本文编号：2133738
[Abstract]:In the process of external load, soft soil subgrade is the consolidation deformation produced by the discharge of pore water. With the compaction of the soil skeleton, the deformation and creep associated with time will be produced under the action of load. How to determine the final settlement of the soft soil subgrade and to discuss the mechanism of soft soil consolidation creep are important for the reinforcement and stability of soft soil. In this paper, based on soil mechanics theory, classical consolidation theory and creep model theory, by carrying out the three axis consolidation creep shear test of soft soil in Panjin coastal road subgrade, the axial deformation of consolidation creep, pore water pressure and so on are obtained, and the two order Kelvin consolidation creep model is proposed, which is based on the search model. The least square algorithm LSMPS (Least Square Method based on Pattern Search) searches and optimizes the parameters of Nikai Hiroyoshi's Kelvin model, and based on the engineering simulation, the consolidation and creep mechanism engineering simulation analysis of soft soil subgrade is carried out. The concrete research results are as follows: (1) the consolidation and creep of three axis soft soil under different confining pressure has been carried out. The relationship between the pore water pressure and the time of the soft soil specimen under different stress levels under the graded loading and the curve of the vertical deformation along with the time are obtained. By using the Chen's loading method, the graded loading curve is transformed into "respectively loading" curve, and the "separately loaded" curve is transformed into the corresponding stress stress stress relationship. It is found that the exponential type function of attenuation can be used to describe the relationship between the deformation and time of soft soil, while the generalized Kelvin creep model is highly similar to the exponential function of the attenuation exponent, so it can be used as the high order generalized Kelvin model constitutive equation. The constitutive equation describing the consolidation and creep characteristics of soft soil samples. (2) using the LSMPS algorithm to model the simplified Nikai Hiroyoshi Kelvin model parameters, search and optimize the parameters of the model by iterative method. It is found that the simplified generalized Kelvin model equation is the monotone function of the parameters of each model. It can be determined that the equation has a unique extreme value on the global level and does not make the pattern search fall into the local optimal. The similarity between the generalized Kelvin model equation and the experimental data determined by the LSMPS algorithm is more than 0.99. Therefore, the model of the parameters determined by this method is used to describe the consolidation and creep of the soft soil. The effect is good. (3) analysis of the soft soil Biot consolidation equation, considering the effect of the additional stress on the Biot consolidation equation caused by the creep of the soft soil, and determining the unified finite element model of the joint action of the consolidation and creep of soft soil: using the powerful engineering simulation platform provided by ADlNA8.4 to transform the model parameters determined by mountain LSMPS into A The parameters of the Lubby2 constitutive model, which are specially used to simulate the creep of rock and soil, are provided in DINA to simulate the distribution of ground stress, pore water pressure and consolidation creep deformation in soft soil subgrade. The above research results can further enrich and improve the consolidation and creep deformation characteristics of soft soil, and effectively control the vertical subsidence of soft soil subgrade. It provides a theoretical basis for reducing and rationally designing reinforcement and stabilization schemes for soft soil roadbed projects.
【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】：2015
【分类号】：U416.16
【参考文献】
相关期刊论文 前10条
1 陈乐意;周立;吴兵;;考虑时间效应的基坑变形数值分析[J];南昌航空大学学报(自然科学版);2013年03期
2 曹文贵;邓湘君;张超;;基于Duncan-Chang模型的地基沉降分层总和分析方法探讨[J];岩土工程学报;2013年04期
3 杨文东;张强勇;陈芳;李术才;李文纲;王建洪;贺如平;曾纪全;;辉绿岩非线性流变模型及蠕变加载历史的处理方法研究[J];岩石力学与工程学报;2011年07期
4 黄文胜;;土的抗剪强度试验成果与其它指标的关系及影响因素分析[J];西北水电;2011年03期
5 胡云世;苏辉;成怡冲;艾智勇;;层状可压缩岩基三维固结问题的状态空间解[J];岩土力学;2011年S1期
6 徐彬;殷宗泽;刘述丽;;膨胀土强度影响因素与规律的试验研究[J];岩土力学;2011年01期
7 张先伟;王常明;;一维压缩蠕变前后软土的微观结构变化[J];岩土工程学报;2010年11期
8 靳晓光;李晓红;;隧道支护结构蠕变特性试验和非线性蠕变模拟[J];重庆大学学报;2010年08期
9 曾玲玲;刘松玉;洪振舜;;天然沉积结构性土的EOP压缩特性[J];东南大学学报(自然科学版);2010年03期
10 吴刚;刘干斌;开前正;;软土地区道路病害原因分析及防治措施[J];公路交通技术;2009年04期
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