地铁车站出入口侧墙冻胀变形数值分析

发布时间：2018-12-12 14:09

【摘要】：随着经济的快速发展,城市规模的不断扩张。在这种形式下,我国轨道交通事业飞速发展。地铁车站作为城市轨道交通的枢纽,其安全性关乎地铁的正常运营,关乎乘客生命及国家财产安全。因此,保障其安全稳定性尤为重要。由于山区温度比平原低很多,因此当地铁车站位于山区时,其在冬季更容易遭受冻害。针对上述问题,本文以北京昌平的十三陵景区车站为工程背景。采用理论分析与数值模拟相结合的方法,研究了该地铁车站在冬季运营时,出入口侧墙周围土层温度场的变化规律,并与天然土层温度场的变化规律进行了比较。在此基础上,通过热-力耦合的方法,计算了地铁车站出入口侧墙的水平冻胀力及水平冻胀位移。通过计算结果分析了水平冻胀力和水平冻胀位移沿侧墙的分布规律。本文的主要研究内容如下:(1)对冻土温度场、水分场及应力场的基本公式进行了研究和推导。对影响土体热交换系数(导热系数、容积热容量)和质交换系数(导湿系数、微分水容量)的各个因素(如总含水量、干密度、未冻水含量)进行了详细的分析。并研究了各个参数的取值方法。(2)当地铁车站在冬季运营时,本文对其出入口侧墙周围土层和天然土层温度场的变化规律进行了分析。研究了土体初始含水率对土层温度场及冻结深度的影响。(3)根据热-力耦合理论及温度与未冻水含量的关系式,本文对土的热膨胀系数的计算公式进行了改进。从理论上推导了封闭系统下饱和土热膨胀系数的计算公式。并将该公式应用到了数值计算当中,计算的结果基本与实际相符。(4)研究了地铁车站出入口侧墙的水平冻胀位移及水平冻胀力沿侧墙的分布规律。分析了土体含水率对侧墙冻胀变形的影响及水平冻胀力随冻结时间的变化规律。最后对比了不同类型出入口的冻胀变形。(5)对比分析了实测值和数值解的结果,证实了水平冻胀力沿埋深的分布规律受土体散热条件(双向冻结、单向冻结)、建筑物的结构形式及地下水埋深的影响。
[Abstract]:With the rapid development of economy, the scale of the city is expanding. In this form, the rapid development of rail transit in China. As the hub of urban rail transit, the safety of subway station is related to the normal operation of subway, the life of passengers and the safety of national property. Therefore, it is particularly important to ensure its safety and stability. The mountain area is much cooler than the plain, so subway stations are more vulnerable to freezing in winter when they are in the mountains. In view of the above problems, this paper takes the Ming Tombs scenic spot station in Changping, Beijing as the engineering background. Using the method of theoretical analysis and numerical simulation, the variation law of soil temperature field around the entrance wall in winter operation of the subway station is studied, and the variation law of temperature field of natural soil layer is compared with that of natural soil layer. On this basis, the horizontal frost heave force and horizontal frost heave displacement of the entrance and exit side wall of subway station are calculated by the thermal-mechanical coupling method. The distribution of horizontal frost heaving force and horizontal frost heave displacement along the side wall is analyzed. The main contents of this paper are as follows: (1) the basic formulas of temperature field, moisture field and stress field of frozen soil are studied and deduced. The factors affecting the heat exchange coefficient (heat conductivity, volumetric heat capacity) and mass exchange coefficient (moisture conductivity, differential water capacity) of soil are analyzed in detail, such as total water content, dry density and unfrozen water content. The methods of selecting the parameters are also studied. (2) when the subway station is in operation in winter, this paper analyzes the variation law of the temperature field in the soil layer and natural soil layer around the entrance and exit side wall. The influence of soil initial moisture content on soil temperature field and freezing depth is studied. (3) based on the thermal-mechanical coupling theory and the relationship between temperature and unfrozen water content, the calculation formula of soil thermal expansion coefficient is improved. The formula for calculating the coefficient of thermal expansion of saturated soil in a closed system is derived theoretically. The formula is applied to the numerical calculation, and the calculated results are basically consistent with the actual results. (4) the horizontal frost heave displacement and the distribution of horizontal frost heave force along the side wall of the entrance and exit side wall of subway station are studied. The influence of soil moisture content on the frost heave deformation of side wall and the variation of horizontal frost heave force with freezing time are analyzed. Finally, the frost heave deformation of different types of entrances and exits are compared. (5) the measured values and numerical results are compared and analyzed. It is proved that the distribution of horizontal frost heave force along the buried depth is subjected to soil heat dissipation conditions (bidirectional freezing, unidirectional freezing). The structural form of buildings and the influence of groundwater depth.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU445

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