移动荷载作用下非饱和地基动力响应理论研究

发布时间：2019-01-22 19:07

【摘要】：近年来随着高速铁路、高速公路的快速发展,地基的动力响应问题受到相关学者的广泛关注。众所周知,高速铁路、高速公路对路基的沉降要求非常严格,而路基的沉降问题与列车荷载、地基类型以及路轨系统等因素有着密不可分的关系。基于此,本文对饱和地基、非饱和地基以及轨道-地基的耦合系统在移动荷载作用下的动力响应进行了详细的研究和探索。首先结合饱和土的Biot动力控制方程,利用Fourier变换技术和Cauchy-Reimann条件,求解得到了饱和地基的位移、应力的积分形式解。同时,采用Fourier逆变换并结合数值算例,详细讨论了移动荷载速度、荷载频率以及饱和土体的渗透系数等因素对饱和地基动力响应的影响。用解析的方法研究了轨道—非饱和地基的耦合系统在移动荷载作用下的动力响应。将钢轨简化为无限长弹性Euler梁,同时考虑了枕木、道渣层的影响。在Fourier变换域内联立轨道和下卧非饱和土体的动力方程,求解得到了移动荷载作用下耦合系统位移、应力的积分形式解。最后通过数值计算考察了非饱和地基饱和度、钢轨刚度等因素对动力响应的影响。天然地基是由复杂的三相体构成的。一般来说,地下水位以下土体可近似地视为饱和土；而地下水位以上土体中由于存在较多气体,将其视为非饱和土才更符合实际。针对这一情况,本文开展了相关研究工作。利用饱和土的Biot动力控制方程以及非饱和土的动力控制方程,得到了移动荷载作用下上覆非饱和层的饱和地基位移、应力积分形式解。并且采用Fourier逆变换给出了数值计算结果,讨论了上覆非饱和土层的饱和度、厚度以及地表排气排水条件等因素对动力响应的影响。
[Abstract]:In recent years, with the rapid development of high-speed railway and expressway, the dynamic response of foundation has been concerned widely. As we all know, the settlement requirement of the high speed railway and highway is very strict, and the settlement problem of the subgrade is closely related to the train load, the type of foundation and the rail system and so on. Based on this, the dynamic response of the coupled system of saturated foundation, unsaturated foundation and rail-foundation under moving load is studied and explored in detail in this paper. Based on the Biot dynamic control equation of saturated soil, the integral solution of displacement and stress of saturated soil is obtained by using Fourier transform technique and Cauchy-Reimann condition. At the same time, the effects of moving load velocity, load frequency and permeability coefficient of saturated soil on the dynamic response of saturated soil are discussed in detail by using Fourier inverse transformation and numerical examples. In this paper, the dynamic response of the coupled system of track to unsaturated foundation under moving load is studied by analytical method. The rail is simplified as an infinite elastic Euler beam and the influence of sleeper and slag layer is considered. The integral solutions of displacement and stress of the coupled system under moving load are obtained by solving the dynamic equations of the simultaneous track and the underlying unsaturated soil in the domain of Fourier transform. Finally, the effects of saturation of unsaturated foundation and rail stiffness on dynamic response are investigated numerically. The natural foundation is made up of complex three-phase bodies. Generally speaking, soil below groundwater level can be considered as saturated soil approximately, but it is more practical to treat soil below groundwater level as unsaturated soil because of the existence of more gases in the soil above groundwater level. In view of this situation, this article has carried out the related research work. By using the Biot dynamic control equation of saturated soil and the dynamic control equation of unsaturated soil, the solutions of displacement and stress integral of saturated foundation overlying unsaturated layer under moving load are obtained. The numerical results are obtained by using the inverse Fourier transform. The effects of saturation, thickness of the overlying unsaturated soil layer and the exhaust and drainage conditions of the surface on the dynamic response are discussed.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU435

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