基于物理性質(zhì)的土體強度和變形特性研究
發(fā)布時間：2019-06-29 12:58
【摘要】：我國東南沿海和部分內(nèi)陸沿江城市(如武漢、昆明等)廣泛存在軟弱黏土,而且工程量巨大。雖然現(xiàn)有土力學(xué)理論對工程實踐有一定的指導(dǎo)作用,但事實表明效果有限。大部分關(guān)于土的強度和變形的理論是以連續(xù)介質(zhì)為對象的研究成果,應(yīng)用到像土這樣的非連續(xù)、結(jié)構(gòu)性強的介質(zhì)中,沒有達到真正解決實際工程問題的目的,如：現(xiàn)有的土體本構(gòu)模型大多沒有充分考慮土的物理特性,模型參數(shù)取值不確定性太大,造成應(yīng)力、應(yīng)變的計算結(jié)果波動過大,在工程應(yīng)用中存在明顯缺陷。為此,本文基于土非連續(xù)介質(zhì)和結(jié)構(gòu)性強的特點,采用現(xiàn)代測試新技術(shù)(彎曲元剪切波速測試),通過土體細觀結(jié)構(gòu)分析試驗與宏觀力學(xué)特性試驗相結(jié)合來探索描述土體結(jié)構(gòu)新方法,建立土的應(yīng)力狀態(tài)方程,提出土體新的強度準則,創(chuàng)立新的結(jié)構(gòu)性土體壓縮特性預(yù)測方法,建立土的物理力學(xué)本構(gòu)模型。并通過數(shù)值分析研究,應(yīng)用新的理論成果解決實際工程問題。本文對闡明非連續(xù)性土體的應(yīng)力狀態(tài)、強度和變形規(guī)律具有重要理論意義和工程應(yīng)用價值。 主要研究內(nèi)容和成果如下： 1、根據(jù)土體的非連續(xù)特性,引入孔隙率這一物性指標,建立土體的應(yīng)力狀態(tài)方程,通過對比分析指出現(xiàn)有強度理論(如莫爾-庫倫理論)的不足。在對正常固結(jié)粘土強度特性簡單的機理分析基礎(chǔ)上,通過一系列常規(guī)三軸固結(jié)壓縮試驗,分析了不同初始孔隙比和塑性指數(shù)對其力學(xué)性質(zhì)的影響。提出一個新的物性參數(shù)ω,該參數(shù)能夠綜合反映出正常固結(jié)飽和粘土的礦物含量及所處狀態(tài),建立了粘土抗剪強度指標與ω之間的關(guān)系,進而考慮對莫爾-庫倫準則進行修正。 2、基于Liu和Carter的結(jié)構(gòu)性破損壓縮模型,提出了一個簡化的物性變化參數(shù)：孔隙相對變化指數(shù)Ev,考慮初始孔隙變化對土體壓縮性狀的影響,通過對杭州原狀軟土進行不同初始振動的固結(jié)試驗,分別建立了孔隙相對變化指數(shù)Ev與土體結(jié)構(gòu)屈服應(yīng)力σy及結(jié)構(gòu)破損指數(shù)b的相關(guān)關(guān)系,據(jù)此提出了新的利用室內(nèi)壓縮試驗結(jié)果預(yù)測原位壓縮曲線的方法。 3、探討了蛋形屈服函數(shù)參數(shù)的確定方法,建立了蛋形屈服函數(shù)參數(shù)a、b、d與土體初始塑性模量的關(guān)系,并將土體的基本物理性質(zhì)指標剪切波速引入到蛋形參數(shù)中；結(jié)合已有的文獻資料,根據(jù)蛋形屈服函數(shù)形狀參數(shù)α與tanφ的變化規(guī)律,發(fā)現(xiàn)具有一致性,提出了α的取值方法。通過一系列室內(nèi)試驗定量地給出了蛋形屈服面參數(shù)與土體初始剪切波速和內(nèi)摩擦角的相關(guān)關(guān)系。 4、在初始彈性模量計算公式中引入結(jié)構(gòu)屈服應(yīng)力po來代替大氣壓力p。,提出了考慮結(jié)構(gòu)性影響的初始彈性模量計算公式,并建立了公式中試驗常數(shù)和初始剪切波速的相關(guān)關(guān)系。在增量塑性理論框架下,以蛋形加載函數(shù)為加載面,以塑性功函數(shù)為硬化參數(shù),運用相關(guān)聯(lián)流動法則,建立了結(jié)構(gòu)性土體的蛋形屈服面彈塑性模型�；谝幌盗袘�(yīng)力路徑壓縮試驗、常規(guī)三軸剪切試驗數(shù)據(jù),確定了該模型參數(shù)的取值。并進一步將剪切波速這個土體基本物理性質(zhì)指標引入到模型參數(shù)中,通過相應(yīng)的彎曲元剪切波速測試試驗定量的給出了模型參數(shù)與土體初始剪切波速的相關(guān)關(guān)系。 5、介紹了彈塑性有限元數(shù)值分析的研究現(xiàn)狀,采用修正牛頓-拉弗森常剛度迭代法結(jié)合隱式回歸本構(gòu)積分算法,并應(yīng)用位移控制法理論建立了蛋形屈服面彈塑性模型的有限元程序。進行三軸試驗條件下的應(yīng)力-應(yīng)變關(guān)系數(shù)值模擬,給出三軸試驗中圓柱體試塊的應(yīng)力-應(yīng)變變化規(guī)律,驗證了本構(gòu)關(guān)系的合理性；最后結(jié)合—擋土結(jié)構(gòu)被動土壓力的數(shù)值算例,驗證了新建有限元程序分析結(jié)果的可行性。
[Abstract]:Soft clay is widely present in the coastal and some inland river cities in the southeast of China (such as Wuhan, Kunming, etc.), and the engineering quantity is huge. Although the existing soil mechanics theory has a certain guiding function to the engineering practice, the fact shows that the effect is limited. Most of the theory about the strength and deformation of the soil is the research result of the continuous medium as the object, and it is applied to the non-continuous and structural medium such as the soil, and the purpose of the real engineering problem is not achieved, such as: Most of the existing constitutive models of the soil have not fully considered the physical characteristics of the soil, the uncertainty of the model parameters is too large, the calculation results of the stress and strain are too large, and there are obvious defects in the engineering application. In this paper, based on the characteristics of the soil non-continuous medium and the strong structure, this paper uses the new technology of modern test (bending element shear wave velocity test) to explore the new method to describe the structure of the soil body through the combination of the micro-structure analysis test of the soil and the test of the macro-mechanical property. The stress state equation of soil is set up, the new strength criterion of the soil body is put forward, and a new method for predicting the compression property of the structural soil is set up, and the physical and mechanical constitutive model of the soil is established. And through the numerical analysis, the new theoretical results are applied to solve the practical engineering problems. In this paper, the stress state, strength and deformation law of the non-continuous soil body are of great theoretical significance and application value. The main research contents and results are as follows: Next:1. According to the non-continuous property of the soil, the physical property index of the porosity is introduced, the stress state equation of the soil body is established, and the existing strength theory (such as the Mohr-Coulomb's theory) is pointed out by the comparative analysis. Based on a series of conventional three-axis consolidation and compression tests, the mechanical properties of different initial pore ratio and plastic index are analyzed on the basis of a series of conventional three-axis consolidation compression tests. In this paper, a new physical parameter model is proposed, which can comprehensively reflect the mineral content and the state of the normal consolidated saturated clay, and establish the relationship between the index of the shear strength and the strength of the clay, and further consider the entry into the Mohr-Coulomb criterion. Line correction.2. Based on the structural damage compression model of Liu and Carter, a simplified physical property change parameter is proposed: the relative change index (Ev) of the pore is considered, and the effect of initial pore change on the soil compression property is considered, and different initial vibration of the original soft soil in Hangzhou is carried out. In this paper, the relationship between the relative change index (Ev) of the pore and the yield stress of the soil structure and the structural damage index (b) is established, and a new method for predicting in-situ compression using the results of the indoor compression test is proposed. The method for determining the parameters of the egg-shaped yield function is discussed. The relationship between the parameters a, b and d of the egg-shaped yield function and the initial plastic modulus of the soil is established, and the shear wave velocity of the basic physical properties of the soil is introduced into the egg-shaped parameters. according to the shape parameters of the egg-shaped yield function and the variation law of the tan, the paper finds that the method has the advantages of consistency, By a series of indoor tests, the parameters of the egg-shaped yield surface and the initial shear wave velocity and the internal friction of the soil body are given in a quantitative way. In this paper, a formula for calculating the initial elastic modulus considering the structural influence is put forward, and the test constant and the initial elastic modulus are set up in the formula. In the framework of incremental plastic theory, the egg-shaped loading function is taken as the loading surface, the plastic work function is the hardening parameter, the associated flow rule is used, and the egg of the structural soil body is established. The elastic-plastic model of the yield surface of the shape. Based on a series of stress path compression tests, the conventional three-axis shear test data is determined. The value of the model parameters is given, and the basic physical property index of the shear wave velocity is introduced into the model parameters, and the model parameters and the initial soil mass are given by the corresponding bending element shear wave velocity test. In this paper, the relation of shear wave velocity is discussed.5. The present situation of the elastic-plastic finite element numerical analysis is introduced. The implicit regression constitutive integral algorithm is combined with the modified Newton-Laver's constant-stiffness iterative method, and the egg-shaped yield surface is established by the theory of displacement control method. The finite element program of the elastic-plastic model is given. The stress-strain relation numerical simulation under the three-axis test condition is carried out. The stress-strain variation rule of the cylinder block in the triaxial test is given, and the rationality of the constitutive relation is verified. A numerical example of the pressure of passive earth is given, and the new finite element method is proved.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU43
本文編號：2507834
[Abstract]:Soft clay is widely present in the coastal and some inland river cities in the southeast of China (such as Wuhan, Kunming, etc.), and the engineering quantity is huge. Although the existing soil mechanics theory has a certain guiding function to the engineering practice, the fact shows that the effect is limited. Most of the theory about the strength and deformation of the soil is the research result of the continuous medium as the object, and it is applied to the non-continuous and structural medium such as the soil, and the purpose of the real engineering problem is not achieved, such as: Most of the existing constitutive models of the soil have not fully considered the physical characteristics of the soil, the uncertainty of the model parameters is too large, the calculation results of the stress and strain are too large, and there are obvious defects in the engineering application. In this paper, based on the characteristics of the soil non-continuous medium and the strong structure, this paper uses the new technology of modern test (bending element shear wave velocity test) to explore the new method to describe the structure of the soil body through the combination of the micro-structure analysis test of the soil and the test of the macro-mechanical property. The stress state equation of soil is set up, the new strength criterion of the soil body is put forward, and a new method for predicting the compression property of the structural soil is set up, and the physical and mechanical constitutive model of the soil is established. And through the numerical analysis, the new theoretical results are applied to solve the practical engineering problems. In this paper, the stress state, strength and deformation law of the non-continuous soil body are of great theoretical significance and application value. The main research contents and results are as follows: Next:1. According to the non-continuous property of the soil, the physical property index of the porosity is introduced, the stress state equation of the soil body is established, and the existing strength theory (such as the Mohr-Coulomb's theory) is pointed out by the comparative analysis. Based on a series of conventional three-axis consolidation and compression tests, the mechanical properties of different initial pore ratio and plastic index are analyzed on the basis of a series of conventional three-axis consolidation compression tests. In this paper, a new physical parameter model is proposed, which can comprehensively reflect the mineral content and the state of the normal consolidated saturated clay, and establish the relationship between the index of the shear strength and the strength of the clay, and further consider the entry into the Mohr-Coulomb criterion. Line correction.2. Based on the structural damage compression model of Liu and Carter, a simplified physical property change parameter is proposed: the relative change index (Ev) of the pore is considered, and the effect of initial pore change on the soil compression property is considered, and different initial vibration of the original soft soil in Hangzhou is carried out. In this paper, the relationship between the relative change index (Ev) of the pore and the yield stress of the soil structure and the structural damage index (b) is established, and a new method for predicting in-situ compression using the results of the indoor compression test is proposed. The method for determining the parameters of the egg-shaped yield function is discussed. The relationship between the parameters a, b and d of the egg-shaped yield function and the initial plastic modulus of the soil is established, and the shear wave velocity of the basic physical properties of the soil is introduced into the egg-shaped parameters. according to the shape parameters of the egg-shaped yield function and the variation law of the tan, the paper finds that the method has the advantages of consistency, By a series of indoor tests, the parameters of the egg-shaped yield surface and the initial shear wave velocity and the internal friction of the soil body are given in a quantitative way. In this paper, a formula for calculating the initial elastic modulus considering the structural influence is put forward, and the test constant and the initial elastic modulus are set up in the formula. In the framework of incremental plastic theory, the egg-shaped loading function is taken as the loading surface, the plastic work function is the hardening parameter, the associated flow rule is used, and the egg of the structural soil body is established. The elastic-plastic model of the yield surface of the shape. Based on a series of stress path compression tests, the conventional three-axis shear test data is determined. The value of the model parameters is given, and the basic physical property index of the shear wave velocity is introduced into the model parameters, and the model parameters and the initial soil mass are given by the corresponding bending element shear wave velocity test. In this paper, the relation of shear wave velocity is discussed.5. The present situation of the elastic-plastic finite element numerical analysis is introduced. The implicit regression constitutive integral algorithm is combined with the modified Newton-Laver's constant-stiffness iterative method, and the egg-shaped yield surface is established by the theory of displacement control method. The finite element program of the elastic-plastic model is given. The stress-strain relation numerical simulation under the three-axis test condition is carried out. The stress-strain variation rule of the cylinder block in the triaxial test is given, and the rationality of the constitutive relation is verified. A numerical example of the pressure of passive earth is given, and the new finite element method is proved.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU43
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