泥炭土地区地铁列车荷载对隧道周围土体振动响应研究

发布时间：2018-10-18 06:32

【摘要】：地铁运营给人们的生活带来了极大的便利,同时长期反复地铁列车荷载作用致使软弱基层基底变形与动力稳定问题已成为社会关注的热点研究问题。鉴于此,本文以昆明泥炭土区隧道周围土体在列车荷载作用下的长期服役性能为研究背景,采用理论分析与数值模拟相结合的研究方法,依据经验公式建立地铁列车荷载,并采用有限元法建立地铁隧道三维模型动力响应的数值模拟途径,对隧道周围土体的动力响应规律进行研究。本文主要研究内容及研究成果如下。首先本文选择经验分析方法,采用人工激励函数模拟地铁不同时速、不同载重下的列车振动荷载。研究地铁时速变化和载重变化对振动荷载的峰值、幅值、频率的影响规律,为探讨振动荷载变化对隧道周围土体振动响应的影响规律奠定基础。其次本文通过有限元方法建立针对昆明泥炭土地区地铁隧道的三维动力响应的数值模拟途径,与前人数值结果进行对比以验证本模型动力分析的正确性,并探讨地铁列车荷载对隧道周围土体的动力响应规律。研究发现地表土层产生的竖向振动加速度最大,纵向振动加速度次之,横向振动加速度最小,并且振动加速度在向远处传播的过程中存在放大现象。隧道基底土层产生的竖向的动应力最大,纵向动应力次之,横向动应力最小,距离荷载作用位置越近的土层其动应力值越大,衰减也越快。最后本文通过改变地铁列车荷载研究了地铁时速变化及载重变化对隧道周围土体振动响应的影响规律。研究发现随着地铁时速的增加,振动加速度峰值增加,但地铁时速变化对振动加速度在传播过程中的放大现象影响较小。地铁时速变化对隧道基底土层动应力峰值影响较小,对动应力衰减影响较小。随着地铁运行载重的提高,在隧道顶面地表土层引起的振动加速度峰值增大,在隧道基底土层中引起的动应力峰值增大。
[Abstract]:Subway operation has brought great convenience to people's life. Meanwhile, the deformation and dynamic stability of soft base foundation caused by repeated train loads for a long time has become a hot issue of social concern. In view of this, taking the long-term service performance of soil around the tunnel in Kunming peat area under train load as the research background, the research method of combining theoretical analysis with numerical simulation is used to establish the subway train load according to empirical formula. The numerical simulation method of dynamic response of the three-dimensional model of subway tunnel is established by using finite element method, and the dynamic response law of soil around the tunnel is studied. The main contents and results of this paper are as follows. In this paper, the method of empirical analysis is used to simulate the train vibration load under different speeds and loads. The effects of the variation of speed and load on the peak value, amplitude and frequency of the vibration load are studied, which lays a foundation for the discussion of the influence of the variation of the vibration load on the vibration response of the soil around the tunnel. Secondly, the finite element method is used to establish a numerical simulation method for the 3D dynamic response of subway tunnel in Kunming peat area, and the numerical results are compared with the previous numerical results to verify the correctness of the dynamic analysis of the model. The dynamic response of subway train load to soil around the tunnel is discussed. It is found that the vertical vibration acceleration is the largest, the longitudinal vibration acceleration is the second, the transverse vibration acceleration is the least, and the vibration acceleration is magnified in the process of spreading to the distance. The vertical dynamic stress is the largest, the longitudinal dynamic stress is the second, and the transverse dynamic stress is the least. The larger the dynamic stress is, the faster the attenuation is. Finally, by changing the train load, this paper studies the influence of subway speed change and load change on the vibration response of soil around the tunnel. It is found that the peak value of the vibration acceleration increases with the increase of the speed of the subway, but the variation of the speed of the subway has little effect on the amplification of the vibration acceleration during the propagation process. The change of subway speed has little influence on the peak value of dynamic stress in the tunnel basement soil layer, and has little effect on the dynamic stress attenuation. With the increase of subway load, the peak value of the vibration acceleration caused by the surface soil layer on the top of the tunnel increases, and the peak value of the dynamic stress in the base layer of the tunnel increases.
【学位授予单位】：云南农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU435;U451.3

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