基于离散—连续耦合方法隧道压力拱问题研究

发布时间：2018-04-04 15:39

本文选题：FLAC　切入点：PFC　出处：《重庆交通大学》2015年硕士论文

【摘要】：隧道作为地下结构物,受到的荷载主要来自周围土体的压力和约束。目前规范中对隧道所受荷载是以深浅埋为界来划分的。深浅埋的界限是以压力拱理论为依据,认为压力拱以上的土体荷载对隧道不再起作用,隧道的荷载主要来自压力拱以下的土体的压力。在地震中,隧道衬砌受到的四周土体产生的作用力还是主要荷载。但在地震时隧道上方的压力拱是否依然存在?如果存在,压力拱的高度是否发生了变化?震后压力拱的高度与震前是否发生了变化?这些问题还无从所知。这些问题是计算地震作用下隧道上方荷载必须解决的问题。为了更好的研究隧道上方土体与隧道衬砌相互作用的问题,必须先研究清楚上述问题。近些年离散元被广泛应用于岩土大变形和破坏的细观机理研究。离散元能从细观方面观察岩土的受力及破坏情况。因此被广泛用于研究岩土的微观力学行为,以及研究微观参数和宏观参数的关系。但采用离散元模拟实际岩土工程问题时需要大量的颗粒,对于目前的计算机处理水平无疑是一个巨大的挑战。此时离散-连续耦合分析方法应运而生,对岩土的大变形区、破裂区或者需要特别关注的区域采用离散元模拟,而其他区域采用连续单元进行模拟。这样即利用了离散元的优点,又解决了计算时间较长的问题。本文在理论分析的基础上编制了耦合程序,利用耦合程序模拟了隧道在静力和地震作用下的受力情况,分析了压力拱的高度问题。本文主要得到的成果有:①编写了“拟FLAC”程序,可完成静力与动力计算,帮助充分理解FLAC2D的实现过程。②编写了离散-连续耦合程序,为研究岩土工程数值模拟新方法做出贡献。③封装了模型生成、室内压缩实验和巴西劈裂实验的函数,可以更快的生成理想模型和测量模型的宏观力学参数。④从力的传递路径改变方面给出了压力拱形成的原因,真正从微观方面解释了压力拱的形成过程,对于充分理解压力拱及压力拱的范围确定给出参考。⑤研究地震作用时压力拱是否存在问题为以后隧道工程设计提供参考。
[Abstract]:As underground structures, tunnels are mainly subjected to the pressure and constraints of surrounding soil.In the current code, the load on the tunnel is divided by depth and shallow burying.The boundary of deep and shallow burying is based on the theory of pressure arch. It is considered that the soil load above the pressure arch no longer acts on the tunnel, and the load of tunnel mainly comes from the pressure of soil below the pressure arch.In the earthquake, the soil force around the tunnel lining is still the main load.But does the pressure arch over the tunnel still exist during the earthquake?If so, has the height of the pressure arch changed?Has the height of the post-earthquake pressure arch changed?These questions are unknown.These problems must be solved to calculate the load above the tunnel under earthquake action.In order to better study the interaction between soil and tunnel lining above the tunnel, the above problems must be studied clearly.In recent years, discrete elements have been widely used to study the mesoscopic mechanism of large deformation and failure of rock and soil.The discrete element can observe the stress and failure of rock and soil from the view of meso.Therefore, it is widely used to study the micromechanical behavior of rock and soil and the relationship between microscopic and macroscopic parameters.But using discrete element to simulate the actual geotechnical engineering problems requires a large number of particles, which is undoubtedly a great challenge to the current computer processing level.At this time, the discrete-time coupled analysis method emerges as the times require. The discrete element is used to simulate the large deformation zone, the fracture zone or the area needing special attention, while the continuous element is used to simulate the other regions.In this way, the advantage of discrete element is utilized, and the problem of long calculation time is solved.On the basis of theoretical analysis, a coupling program is developed in this paper. By using the coupling program, the stress of the tunnel under static and seismic action is simulated, and the height of the pressure arch is analyzed.The main results of this paper are as follows: 1 wrote the "quasi FLAC" program, which can accomplish static and dynamic calculation, and help to fully understand the realization process of FLAC2D. 2. A discrete-time and continuous coupling program is written.In order to study the new method of geotechnical engineering numerical simulation, the paper encapsulates the functions of model generation, indoor compression experiment and Brazilian splitting experiment.The macroscopic mechanical parameters of the ideal model and the measurement model. 4. The causes of the formation of the pressure arch are given in terms of the change of the force transfer path, and the formation process of the pressure arch is really explained from the micro aspect.In order to fully understand the range of pressure arch and pressure arch, the paper gives the reference .5 to study whether the pressure arch exists in earthquake action or not, which provides a reference for future tunnel engineering design.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451

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