考虑土拱效应挡土墙主动土压力研究

发布时间：2018-03-14 02:21

本文选题：挡土墙　切入点：土拱效应　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：挡土墙是土木建筑、水利水电、铁道交通等工程建设中广泛使用的一种结构物,挡土墙破坏时,不仅影响工程的基础建设,而且在地震时还可能引发次生灾害,因此在挡土墙设计时需要有比较准确的土压力计算理论作为指导。以往的研究在考虑土拱效应后,对土拱的形状缺乏应力分析,而且仅局限于对直线滑裂面情况下的土压力进行求解,尤其是在地震作用下,忽略了地震系数对侧土压力系数的影响。本文以垂直、刚性挡土墙为研究对象,通过对墙后土体的应力分析,并且考虑了土拱效应,对静力状态下和地震作用下的主动土压力进行研究,其中在静力状态下分别对直线滑裂面和旋轮线滑裂面求解主动土压力。首先考虑土体的拱效应,通过对墙后土体的应力分析,得到土拱的形状,应用水平层分析法,推导出挡土墙平移模式下的主动土压力分布、土压力合力以及合力作用点高度的理论公式,并在此基础上研究了土体参数对土压力结果的影响。计算结果表明：考虑土拱效应后,得到的土压力合力作用点高度小于不考虑土拱效应计算出的结果,但始终大于库伦理论计算出的结果,所以应用库伦理论设计挡土墙偏危险。然后假设墙后土体滑裂面为旋轮线,首次将土拱原理应用到旋轮线滑裂面,其方法可推广至其他曲线滑裂面,具有重要的理论意义。改进了前人应用旋轮线滑裂面计算土压力的数学模型,通过数值求解,得到了主动土压力的分布情况,并和采用直线滑裂面计算出的结果以及其他方法进行比较分析,另外也研究了土体参数对滑裂面位置和土压力结果的影响。结果表明：当墙土摩擦角与土体内摩擦角比值接近1时,计算出的土压力合力大于库伦理论计算值,这在实际工程设计中值得注意。在地震情况下基于Mononobe-Okabe理论,考虑土拱效应,通过对墙后土体的应力分析推导出地震作用下的土拱形状的曲线方程,计算出在不同的地震系数下的侧土压力系数值,应用水平层分析法推导出地震主动土压力的强度、土压力合力以及合力作用点高度的计算公式,并与M-O理论和现有方法进行对比分析,并分析了各个参数对结果的影响。计算结果表明：计算出的地震土压力合力与M-O理论相同,但是呈非线性分布,地震土压力的分布对水平地震系数的变化较敏感,当地震系数较大时,土压力合力作用点高度远大于M-O理论的计算值,所以若按照M-O理论设计挡土墙偏危险。本论文结果对挡土墙的设计有指导作用。
[Abstract]:Retaining wall is a kind of structure which is widely used in civil construction, water conservancy and hydropower, railway traffic and so on. When the retaining wall is destroyed, it not only affects the basic construction of the project, but also may cause secondary disasters during earthquake. Therefore, in the design of retaining wall, it is necessary to have more accurate earth pressure calculation theory as the guidance. The previous studies lack of stress analysis on the shape of soil arch after considering the effect of soil arch. Moreover, it is only limited to the solution of earth pressure in the case of linear sliding surface, especially under earthquake, and the influence of seismic coefficient on lateral earth pressure coefficient is ignored. In this paper, vertical and rigid retaining wall is taken as the research object. By analyzing the stress of soil behind the wall and considering the effect of soil arch, the active earth pressure under static and seismic action is studied. In the static state, the active earth pressure is solved for the linear slip surface and the rotating wheel line slip surface respectively. Firstly, considering the arch effect of soil, the shape of the soil arch is obtained through the stress analysis of the soil behind the wall, and the horizontal layer analysis method is used. The distribution of active earth pressure, the force of earth pressure and the height of the working point of the earth retaining wall under the translational mode of retaining wall are derived. On this basis, the influence of soil parameters on the soil pressure results is studied. The calculated results show that the calculated height of the earth pressure joint force is lower than that without the soil arch effect. But it is always larger than that calculated by Coulomb's theory, so it is dangerous to apply Coulomb's theory to design retaining wall. Then, assuming that the slip surface of soil behind the wall is rotary wheel line, the principle of soil arch is applied to the slip surface of rotary wheel line for the first time. The method can be extended to other curvilinear slip surfaces and has important theoretical significance. The mathematical model for calculating earth pressure by using the linear slip surface of rotary wheel is improved, and the distribution of active earth pressure is obtained by numerical solution. The results calculated by using linear slip surface and other methods are compared and analyzed. In addition, the influence of soil parameters on the location of sliding surface and the result of earth pressure is also studied. The results show that when the ratio of friction angle of wall and soil is close to 1:00, the calculated resultant force of earth pressure is greater than the calculated value of Coulomb's theory. This is worthy of attention in practical engineering design. Based on the Mononobe-Okabe theory and considering the soil arch effect, the curve equation of soil arch shape under earthquake action is derived through the stress analysis of soil behind the wall. The lateral earth pressure coefficients under different seismic coefficients are calculated, and the formulas for calculating the strength of the active earth pressure, the resultant force of the earth pressure and the height of the joint action point are derived by using the horizontal layer analysis method. Compared with M-O theory and existing methods, the influence of various parameters on the results is analyzed. The calculated results show that the calculated earth pressure forces are the same as M-O theory, but nonlinear distribution. The distribution of seismic earth pressure is sensitive to the variation of horizontal seismic coefficient. When the seismic coefficient is large, the height of the earth pressure acting point is much higher than the calculated value of M-O theory. So it is dangerous to design retaining wall according to M-O theory. The results of this paper can guide the design of retaining wall.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU432

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