【摘要】：軟土路基在受到外界荷載作用過(guò)程中,先期是由孔隙水排出產(chǎn)生的固結(jié)變形,隨著土體骨架被壓密,在荷載的作用下會(huì)產(chǎn)生與時(shí)間有關(guān)的形變—蠕變。如何確定軟土路基最終沉降量及探討軟土固結(jié)-蠕變機(jī)理成為軟土加固與穩(wěn)定的重要研究方向。本文以土力學(xué)理論、經(jīng)典固結(jié)理論、蠕變模型理論為基礎(chǔ),通過(guò)開(kāi)展室內(nèi)盤(pán)錦濱海公路路基軟土三軸固結(jié)蠕變剪切試驗(yàn)獲取軟土固結(jié)蠕變軸向變形、孔隙水壓力等數(shù)據(jù),提出了二階廣義Kelvin固結(jié)-蠕變模型,利用基于搜索模式的最小二乘算法一LSMPS (Least Square Method based on Pattern Search)對(duì)二階廣義的Kelvin模型的參數(shù)進(jìn)行搜索與優(yōu)化,并且以工程仿真為依托,進(jìn)行軟土路基固結(jié)-蠕變機(jī)理工程仿真分析。具體研究成果如下：(1)開(kāi)展了不同圍壓下軟土三軸固結(jié)-蠕變?cè)囼?yàn),獲得了分級(jí)加載下軟土試樣在不同偏應(yīng)力水平下的孔隙水壓與時(shí)間的關(guān)系以及豎向變形隨時(shí)間發(fā)展的曲線,利用陳氏加載法將分級(jí)加載曲線轉(zhuǎn)化為“分別加載”曲線,利用同一時(shí)刻應(yīng)力應(yīng)變關(guān)系將“分別加載”曲線轉(zhuǎn)化為應(yīng)力應(yīng)變等時(shí)曲線。通過(guò)試驗(yàn)研究發(fā)現(xiàn)采用衰減的指數(shù)類型函數(shù)可以描述軟土的變形-時(shí)間之間的函數(shù)關(guān)系,而廣義的Kelvin蠕變模型本構(gòu)方程和衰減的指數(shù)函數(shù)之間具有高度的相似特征,因此可以使用高階廣義的Kelvin模型本構(gòu)方程作為描述軟土試樣的固結(jié)-蠕變特征的本構(gòu)方程。(2)利用LSMPS算法對(duì)簡(jiǎn)化的二階廣義的Kelvin模型的參數(shù)進(jìn)行模式化搜索,對(duì)模型的參數(shù)通過(guò)迭代的方法進(jìn)行搜索和優(yōu)化,研究發(fā)現(xiàn),簡(jiǎn)化的廣義Kelvin模型方程是各模型參數(shù)的單調(diào)函數(shù),在理論上可以確定該方程在全局上存在唯一的極值而不會(huì)使模式化搜索陷入局部最優(yōu)。對(duì)比通過(guò)LSMPS算法確定的廣義Kelvin模型方程與試驗(yàn)數(shù)據(jù)之間的相似度,相關(guān)性系數(shù)均在0.99以上,因此,使用該方法所確定參數(shù)的模型在描述軟土固結(jié)-蠕變特征方面效果較好。(3)分析了軟土Biot固結(jié)方程,考慮軟土發(fā)生蠕變時(shí)產(chǎn)生的節(jié)點(diǎn)附加應(yīng)力對(duì)Biot固結(jié)方程的影響,確定了軟土固結(jié)-蠕變共同作用時(shí)的統(tǒng)一有限元模型：利用ADlNA8.4提供的強(qiáng)大工程仿真平臺(tái)將山LSMPS確定的模型參數(shù)轉(zhuǎn)化為ADINA中提供的專門(mén)用于模擬巖土蠕變的Lubby2本構(gòu)模型各參數(shù),使之模擬軟土路基的地應(yīng)力、孔隙水壓力、固結(jié)-蠕變變形在軟土路基內(nèi)部的分布狀況。以上研究成果為進(jìn)一步豐富和完善軟土固結(jié)-蠕變變形特征、有效控制軟土路基的豎向沉降以及合理設(shè)計(jì)軟土路基工程的加固穩(wěn)定方案提供了理論依據(jù)。
[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.
【學(xué)位授予單位】：遼寧工程技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U416.16

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