动荷载条件下冻土融化固结与变形研究
发布时间：2019-05-09 04:22
【摘要】：目前,国内外学者针对高温冻土融沉机理及其融沉性状等方面做了大量研究工作,但这些研究主要集中在静荷载作用下土体的融沉特性,很少涉及到动荷载对水分迁移、冻胀融沉翻浆的作用,尤其是没有考虑孔隙水压力的变化对路基土体沉降的影响。但是对于实际工程,车辆动荷载才能较真实地反映外界荷载状况,孔隙水压力的消散以及融化过程中水分的迁移和变化正是解释融沉现象实质的关键,对保证道路安全运营具有重要意义。 本文以国家自然基金课题“高温冻土动力融化固结理论研究”为依托,以109国道青海省境内橡皮山段公路路基上严重翻浆地段为重点,采用现场调研和实测、理论分析、及数值模拟和室内试验验证相结合的思路,对于高温冻土动力融化固结特性进行系统研究,从而进一步完善冻土动力学的学科体系。取得了以下几个方面的研究成果： (1)针对超载及冻土性质引起的路基冻胀翻浆问题,通过现场实测,对G109在重型交通车辆作用下,不同深度、不同载重、不同车速的路基动态响应规律进行了研究,并对G109沿线的路基动态响应状态数据进行了长期的观测。 (2)考虑不同冷却温度和融化温度时土体分别在自重荷载和动荷载的作用下,对109国道路基代表性土进行饱和状态下的融化固结作用研究,研究其在开敞系统有侧限、不同温度和荷载边界条件作用下土体孔隙水压力的变化规律。 (3)对饱和冻土在轴对称条件下的三维融化固结理论进行了推导,以圆柱体试件为研究对象,推导出按位移求解空间间间轴对称问题时的基本微分方程。从三场的基本方程出发,结合冻土融化固结过程中的孔隙冰压力和孔隙水压力的转化规律,导出饱和冻土融化固结理论模型。 (4)考虑孔隙气压力的作用,修订有效应力的表达式,考虑渗透系数为孔隙水压力和孔隙气压力的函数,结合土体颗粒、水、冰和气体的质量守恒方程以及动量守恒方程,依据达西定律来表达气体和水的平均运动速度,推导出非饱和高温冻土融化固结理论模型。 (5)利用数值模拟方法,深入研究车辆动荷载作用下冻土路基的融化固结,分别建立室内试验验证模型和季节性冻土地区109国道橡皮山段冻土路基有限元模型,综合分析了不同边界条件下高温冻土融化固结沉降。图59幅,表11个,参考文献131篇。
[Abstract]:At present, scholars at home and abroad have done a lot of research on the thawing mechanism of high-temperature frozen soil and its melting state, but these researches mainly focus on the melting and sinking characteristics of soil under static load, and rarely involve the dynamic load to water transfer. The effect of frost heave and thaw grouting, especially the influence of pore water pressure on the settlement of subgrade soil is not considered. But for the actual engineering, the vehicle dynamic load can reflect the external load condition more realistically, the dissipation of pore water pressure and the movement and change of water in the melting process are the key to explain the essence of the melting and sinking phenomenon. It is of great significance to ensure the safe operation of the road. Based on the National Nature Fund project "theoretical study on dynamic melting consolidation of High temperature Frozen soil", this paper focuses on the seriously overturned section of highway roadbed in the rubber mountain section of National Highway 109 in Qinghai Province, and adopts field investigation and measurement, theoretical analysis, and so on. With the combination of numerical simulation and laboratory test, the dynamic melting and consolidation characteristics of high temperature permafrost are systematically studied, so as to further improve the discipline system of frozen soil dynamics. The research results are as follows: (1) aiming at the problem of frost heave and grouting of subgrade caused by overload and frozen soil properties, through field measurement, the G109 under the action of heavy traffic vehicles, different depth, different load, The dynamic response law of roadbed with different speed is studied, and the data of subgrade dynamic response along G109 are observed for a long time. (2) considering the different cooling temperature and melting temperature, the melting and consolidation of 109 national highway subgrade representative soil under saturated state is studied under the action of self-weight load and dynamic load, respectively, and the lateral limit of the soil in the open system is studied. Variation of pore water pressure of soil under different temperature and load boundary conditions. (3) the three-dimensional thawing consolidation theory of saturated frozen soil under axisymmetric condition is derived. The basic differential equation for solving the spatial axisymmetric problem according to displacement is derived by taking the cylinder specimen as the research object. Based on the basic equations of three fields, combined with the transformation of pore ice pressure and pore water pressure during thawing and consolidation of frozen soil, a theoretical model of thawing and consolidation of saturated permafrost is derived. (4) considering the effect of pore gas pressure, the expression of effective stress is revised, and the permeability coefficient is considered as a function of pore water pressure and pore gas pressure, combined with the mass conservation equation of soil particles, water, ice and gas, as well as the momentum conservation equation. According to Darcy's law, the average velocity of gas and water is expressed, and the theoretical model of thawing consolidation of unsaturated high temperature permafrost is derived. (5) the melting consolidation of frozen soil roadbed under vehicle dynamic load is deeply studied by numerical simulation method, and the laboratory test verification model and the finite element model of permafrost roadbed of 109 National Highway in seasonal frozen soil area are established respectively. The melting and consolidation settlement of high temperature frozen soil under different boundary conditions is comprehensively analyzed. Figure 59, table 11, 131 references.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U416.16
本文编号：2472470
[Abstract]:At present, scholars at home and abroad have done a lot of research on the thawing mechanism of high-temperature frozen soil and its melting state, but these researches mainly focus on the melting and sinking characteristics of soil under static load, and rarely involve the dynamic load to water transfer. The effect of frost heave and thaw grouting, especially the influence of pore water pressure on the settlement of subgrade soil is not considered. But for the actual engineering, the vehicle dynamic load can reflect the external load condition more realistically, the dissipation of pore water pressure and the movement and change of water in the melting process are the key to explain the essence of the melting and sinking phenomenon. It is of great significance to ensure the safe operation of the road. Based on the National Nature Fund project "theoretical study on dynamic melting consolidation of High temperature Frozen soil", this paper focuses on the seriously overturned section of highway roadbed in the rubber mountain section of National Highway 109 in Qinghai Province, and adopts field investigation and measurement, theoretical analysis, and so on. With the combination of numerical simulation and laboratory test, the dynamic melting and consolidation characteristics of high temperature permafrost are systematically studied, so as to further improve the discipline system of frozen soil dynamics. The research results are as follows: (1) aiming at the problem of frost heave and grouting of subgrade caused by overload and frozen soil properties, through field measurement, the G109 under the action of heavy traffic vehicles, different depth, different load, The dynamic response law of roadbed with different speed is studied, and the data of subgrade dynamic response along G109 are observed for a long time. (2) considering the different cooling temperature and melting temperature, the melting and consolidation of 109 national highway subgrade representative soil under saturated state is studied under the action of self-weight load and dynamic load, respectively, and the lateral limit of the soil in the open system is studied. Variation of pore water pressure of soil under different temperature and load boundary conditions. (3) the three-dimensional thawing consolidation theory of saturated frozen soil under axisymmetric condition is derived. The basic differential equation for solving the spatial axisymmetric problem according to displacement is derived by taking the cylinder specimen as the research object. Based on the basic equations of three fields, combined with the transformation of pore ice pressure and pore water pressure during thawing and consolidation of frozen soil, a theoretical model of thawing and consolidation of saturated permafrost is derived. (4) considering the effect of pore gas pressure, the expression of effective stress is revised, and the permeability coefficient is considered as a function of pore water pressure and pore gas pressure, combined with the mass conservation equation of soil particles, water, ice and gas, as well as the momentum conservation equation. According to Darcy's law, the average velocity of gas and water is expressed, and the theoretical model of thawing consolidation of unsaturated high temperature permafrost is derived. (5) the melting consolidation of frozen soil roadbed under vehicle dynamic load is deeply studied by numerical simulation method, and the laboratory test verification model and the finite element model of permafrost roadbed of 109 National Highway in seasonal frozen soil area are established respectively. The melting and consolidation settlement of high temperature frozen soil under different boundary conditions is comprehensively analyzed. Figure 59, table 11, 131 references.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U416.16
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