黄土隧道基底围岩静动力特性分析
发布时间：2019-03-22 06:34
【摘要】：随着我国铁路的快速发展，穿越黄土地层的隧道越来越多。隧道穿越黄土地区，由于黄土的特殊力学性质，基底的承载力通常较难满足结构的受力性能。黄土隧道基底区域静动力特性，直接关系到隧道基底承载力是否能满足结构稳定及运营安全的要求。同时，隧道底部基岩是整个隧道结构的基础，其在列车荷载长期循环加、卸载作用下的性状对隧道底部乃至整个隧道结构受力都有显著影响。随着列车运行速度的提高，对基底围岩的变形也提出了更高的要求，因此研究在列车长期荷载作用下的基底累计沉降变形显得尤为重要。本文主要研究内容和成果如下： (1)在静力分析方面对几种确定围岩压力的传统经验理论方法进行了对比分析，，分析得出全土柱法算出的基底围岩压力最大，卡柯公式最小。 (2)在静力分析方面利用数值模拟的方法对隧道不同施工方法、隧道不同埋深、黄土本身力学参数(黏聚力、内摩擦角)等方面对黄土隧道基底围岩应力进行研究，得出不同施工方法对隧道基底围岩竖向应力的影响比较大；随着隧道埋深的增大，隧道基底围岩竖向应力也增大；黄土本身力学参数(黏聚力、内摩擦角)影响比较小可以忽略不计等规律。 (3)对隧道底部基岩动力响应特性进行了系统的分析。用一个激励函数的形式来模拟列车荷载，对四种不同时速(200km/h、250km/h、300km/h、350km/h)列车荷载进行了数值模拟，分析了竖向位移加速度和竖向应力随四种不同列车时速荷载总用下的分布规律。数值模拟结果表明：随着列车时速的增大，加速度峰值和基底总竖向应力峰值都增大。 (4)对隧道基底围岩在列车循环荷载作用下累计沉降进行了分析，采用DingQing Li模型对累计塑性应变进行分析。对四种不同列车时速荷载作用下累计沉降值进行了计算，得出运营初期累计沉降发展非常快，随后累计沉降发展非常缓慢，最后趋于稳定状态，隧道基底累计沉降值随着列车时速的提高而增大。
[Abstract]:With the rapid development of railway in China, more and more tunnels pass through loess stratum. Because of the special mechanical properties of loess, the bearing capacity of the foundation is usually difficult to meet the mechanical performance of the structure. The static and dynamic characteristics of loess tunnel basement region are directly related to whether the bearing capacity of tunnel basement can meet the requirements of structural stability and operation safety. At the same time, the bedrock at the bottom of the tunnel is the foundation of the whole tunnel structure. Under the long-term cyclic loading and unloading of the train load, the behavior of the foundation rock has a significant effect on the stress of the tunnel bottom and even the whole tunnel structure. With the increase of train running speed, the deformation of basement rock is required more and more. Therefore, it is very important to study the accumulative settlement deformation of basement under long-term load. The main contents and achievements of this paper are as follows: (1) in the aspect of static analysis, several traditional empirical methods for determining the pressure of surrounding rock are compared and analyzed, and the maximum pressure of the base rock calculated by the whole soil column method is obtained. The Carke formula is the smallest. (2) in the aspect of static analysis, numerical simulation is used to study the stress of surrounding rock of loess tunnel in different construction methods, different buried depth of tunnel, mechanical parameters of loess itself (cohesion force, internal friction angle) and so on. It is concluded that the influence of different construction methods on the vertical stress of surrounding rock of tunnel basement is relatively large. With the increase of tunnel depth, the vertical stress of surrounding rock of tunnel basement increases, and the influence of loess mechanical parameters (cohesion, internal friction angle) is negligible. (3) the dynamic response characteristics of bedrock at the bottom of tunnel are analyzed systematically. In the form of an excitation function, the train loads of four different speeds (200 km / h, 250 km / h, 300 km / h, 350 km / h) are numerically simulated. The distribution law of vertical displacement acceleration and vertical stress with the total speed load of four kinds of trains is analyzed. The numerical simulation results show that the peak acceleration and the peak value of the total vertical stress increase with the increase of train speed. (4) the accumulative settlement of surrounding rock of tunnel foundation under train cyclic load is analyzed, and the accumulative plastic strain is analyzed by DingQing Li model. The accumulative settlement values under four different train speed loads are calculated, and the results show that the accumulative settlement develops very quickly in the initial stage of operation, and then develops very slowly, and finally tends to a stable state. The cumulative settlement of tunnel substrate increases with the increase of train speed.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U452.1
本文编号：2445346
[Abstract]:With the rapid development of railway in China, more and more tunnels pass through loess stratum. Because of the special mechanical properties of loess, the bearing capacity of the foundation is usually difficult to meet the mechanical performance of the structure. The static and dynamic characteristics of loess tunnel basement region are directly related to whether the bearing capacity of tunnel basement can meet the requirements of structural stability and operation safety. At the same time, the bedrock at the bottom of the tunnel is the foundation of the whole tunnel structure. Under the long-term cyclic loading and unloading of the train load, the behavior of the foundation rock has a significant effect on the stress of the tunnel bottom and even the whole tunnel structure. With the increase of train running speed, the deformation of basement rock is required more and more. Therefore, it is very important to study the accumulative settlement deformation of basement under long-term load. The main contents and achievements of this paper are as follows: (1) in the aspect of static analysis, several traditional empirical methods for determining the pressure of surrounding rock are compared and analyzed, and the maximum pressure of the base rock calculated by the whole soil column method is obtained. The Carke formula is the smallest. (2) in the aspect of static analysis, numerical simulation is used to study the stress of surrounding rock of loess tunnel in different construction methods, different buried depth of tunnel, mechanical parameters of loess itself (cohesion force, internal friction angle) and so on. It is concluded that the influence of different construction methods on the vertical stress of surrounding rock of tunnel basement is relatively large. With the increase of tunnel depth, the vertical stress of surrounding rock of tunnel basement increases, and the influence of loess mechanical parameters (cohesion, internal friction angle) is negligible. (3) the dynamic response characteristics of bedrock at the bottom of tunnel are analyzed systematically. In the form of an excitation function, the train loads of four different speeds (200 km / h, 250 km / h, 300 km / h, 350 km / h) are numerically simulated. The distribution law of vertical displacement acceleration and vertical stress with the total speed load of four kinds of trains is analyzed. The numerical simulation results show that the peak acceleration and the peak value of the total vertical stress increase with the increase of train speed. (4) the accumulative settlement of surrounding rock of tunnel foundation under train cyclic load is analyzed, and the accumulative plastic strain is analyzed by DingQing Li model. The accumulative settlement values under four different train speed loads are calculated, and the results show that the accumulative settlement develops very quickly in the initial stage of operation, and then develops very slowly, and finally tends to a stable state. The cumulative settlement of tunnel substrate increases with the increase of train speed.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U452.1
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