【作者】 徐满清；

【导师】 金腊华；

【作者基本信息】 南昌大学 ， 环境工程， 2010， 博士

【摘要】 本文根据国内《城市区域环境振动标准》GB 10070-88关于交通荷载诱发的环境振动评价方法的规定,结合土动力学,充分考虑交通荷载引起环境振动的复杂性,注意到岩土情况的复杂性,采用交通荷载---轨道---饱和土体模型模拟了交通荷载引起环境振动的传播和衰减规律,同时在排桩对交通荷载引起地面振动的隔振减振工程措施机理进行了系统研究,主要包括以下几个方面：1)阐述了轨道交通振动传播的物理机制、评价标准以及描述振动特性的主要参数指标和评价指标,也给出了轨道交通引起环境振动的实用公式。2)把轨道作为弹性地基上的梁,考虑轨枕的离散支撑,建立了交通荷载---轨道---地基振动模型；针对轨道交通引起的环境振动的大量的研究成果主要局限于单相介质,没有考虑孔隙水的影响。从饱和土的Biot波动方程出发,采用Fourier变换方法解耦Biot动力方程,根据传递、透射矩阵原理,对分层地基上列车运行引起的地面振动进行了分析。根据推导的交通荷载---轨道---地基振动模型,详细讨论了列车运行速度、土体渗透系数、孔隙率、流体粘滞系数、剪切波速、土体层状性等主要土层参数对振动响应的影响。3)采用数值分析方法研究了排桩对交通荷载引起土体环境振动的控制机理。利用结构工程理论和Muki法及积分方程方法,饱和土体满足Biot理论,隔振桩作为1-D杆,分析了移动荷载振源下排桩的被动隔振效果。对影响排桩隔振的因素：刚度、排桩桩长、桩间距及土体层状性等作了分析,并与已知文献结果进行了比较,验证本文方法的正确性。文中方法避免了边界元法(BEM)、有限元法(FEM)需要在计算响应域进行节点划分问题,因此可极大减小计算机分析的时间。由数值分析可得：影响隔振效果的主要参数包括：排桩的排数、排桩桩长、桩土刚度比、桩桩间距等,而排-排间距对隔振效果的影响不明显。另外,排桩对低速的移动荷载的隔振效果要比高速时好,而且相同的隔振体系,排桩对相同的振源在饱和土比弹性土体中的隔振效果较好。更多还原

【Abstract】 According to the evaluation method of environmental vibration induced by traffic loading formulated by the state regulation of "regional environmental criteria for vibration in urban construction" (GB10070-88), and based on the dynamic soil mechanics theory as well as considering the complex nature of the environmental vibration induced by traffic loading. The environmental vibration propagation and attenuation rule is analyzed with using the model of traffic load-railway track-saturated soil. Meanwhile, special attention is also paid to the study of the isolation vibration mechanism by using pile rows in this paper. The studies of the paper consist of the following parts:1) The physical mechanism of vibration propagation and attenuation is introduced briefly. Also, the main control parameters of vibration character are presented and the formula to calculate the ground vibration induced by track traffic is given.2) Considering the railway track as the elastic foundation beam and regarded the discrete support by concrete sleeper, the simplified model of the traffic load-train-railway track-soil foundation was established. Some scholars have studied the problem of environment vibration induced by traffic loading, however, the influence of pore water pressure without taking into account in their researches. Based on Biot’s theory and using the Fourier transform, The time domain solutions for the half space are obtained, Consequently, the transmission and reflection matrices (TRM) method is used in solving the problem of environment vibration induced by traffic loading in the layered water-saturated poro-elastic half space. Furthermore, the effect of soil layer parameters on the vibration response of the ground, such as the speed of the train, infiltration coefficient, the porosity, the viscosity of a fluid, shear wave velocity and the layered saturated soils, is discussed in detail.3) The effect of vibration isolation by using pile rows embedded in a poroelastic half space is investigated with the semi-analytical methods. Taken the pile as 1-D bar, using Biot theory and Muki and Sternberg’s method as well as the integral equation, the effect of isolation the vibration due to the moving loads by using pile rows embedded in a poroelastic half space is investigated in this study. The influences of the soil inhomogeneity, pile length, Young’s modulus of the pile, the net spacing between two neighboring piles in a row are investigated by numerical simulation. Also, the influence of the number of pile rows and spacing between pile rows are examined. Comparison of our results with an existing result shows that our results are in a good agreement with the existing one. The semi-analytical nature of the proposed method avoids the discretization of the whole calculation domain which is necessary for finite element method, and thus it reduces the CPU time for the current problem substantially. So the proposed method is useful for the design of vibration isolation barriers and can be used to evaluate the effect of pile rows as barrier system for ground vibrations. Numerical results suggest that the pile length, the number of pile rows, the spacing between neighboring piles in each pile row and the stiffness of piles have significant influence on the vibration isolation effect of pile rows. While the spacing between the neighboring pile rows may have little influence on the vibration isolation effect. Numerical results of this study also show that speed of moving loads has an important impact on the isolation vibration effect of pile rows:the same pile rows can achieve better vibration isolation effect for lower speed loads than for higher speed loads. Moreover, for the same pile rows and the vibration source, the poroelastic medium often leads to a better vibration isolation effect than the single phase elastic medium does.更多还原