路堤涵洞土压力三维数值计算及理论研究

发布时间：2018-04-16 10:01

本文选题：路堤涵洞 + 坡度　；参考：《太原理工大学》2014年硕士论文

【摘要】：随着我国经济的发展,水利、公路、铁路工程建设越来越多,特别是山区高等级公路、铁路的建设,涵洞被大量采用。路堤涵洞土压力的计算理论和方法多种多样,缺乏较为统一合理的计算理论和方法。每一种方法,都有其相对的局限性,结构计算结果不甚相同。涵洞结构估计不足,则病害频现,导致工程不能正常使用；相反,工程设计过分保守,则造成工程经济不合理。路堤涵洞结构体系属于三维结构形式,涵洞安全受涵洞周围土压力的影响很大,而洞顶垂直土压力对涵洞结构安全起决定作用。作者采用三维有限元分析的方法,从空间角度对路堤涵洞进行研究。本文以路堤坡度为切入点,研究刚性地基和软性地基情况下涵洞顶部垂直土压力在路堤边坡不同情况下的变化规律。本文的研究内容如下：(1)采用大型有限元分析商业软件ANSYS,建立三维有限元模型。刚性地基情况下,以箱涵为研究对象,分析不同坡度、不同填土高度及不同坡高情况下涵洞顶部垂直土压力的分布规律。研究结果表明：土压力系数均大于1,应力集中现象明显；坡度、坡高一定时,土压力系数随着填土高·度的增加呈现先增大后减小的趋势；坡度、填土高度一定时,随着坡高的增加土压力系数呈现非线性增大趋势最后趋于稳定；坡高一定,在一定填土高度范围内,坡度越大,土压力系数越大,超过这个范围土压力系数差异很小。涵洞顶部垂直土压力随填土高度、坡高的增大呈现非线性增大趋势。当坡高、填土高度较小时,土压力值随着坡度的增大而增大；当坡高、填土高度较大时,土压力值随着坡度的增大而减小。 (2)刚性地基情况下,分析了路面下涵洞段顶部垂直土压力系数随坡高(填土高度)和坡度的变化规律,路中线处涵洞顶部垂直土压力随坡高的变化规律。研究结果表明,路中线处涵洞顶部垂直土压力随坡高的增大呈非线性增大趋势,拟合得出土压力公式为二次多项式。 (3)软性地基情况下,以箱涵为研究对象,分析了不同坡度、不同填土高度情况下涵洞顶部土压力的分布规律。 (4)数值模拟涵洞的施工过程,即分层填土的过程。对比一次性填土的数值计算,分析涵洞结构和土体相互作用下填土位移的变化趋势。 (5)边坡下涵洞体系的理论公式研究。结合理论推导及曲线拟合所得二次多项式,对比分析得出路堤涵洞顶部垂直土压力的非线性计算公式,方便工程参考。
[Abstract]:With the development of economy in our country, more and more water conservancy, highway and railway projects are being constructed, especially the construction of high grade highway and railway in mountainous areas, and culverts are widely used.There are a variety of theories and methods for calculating the earth pressure of embankment culverts, and there is no unified and reasonable calculation theory and method.Each method has its relative limitation and the result of structure calculation is not the same.If the estimate of culvert structure is insufficient, the disease will occur frequently, which will result in the project not being used normally; on the contrary, the engineering design is too conservative and the engineering economy is unreasonable.The structure system of embankment culvert belongs to three-dimensional structure, and the safety of culvert is greatly affected by the earth pressure around culvert, and the vertical earth pressure at the top of culvert plays a decisive role in the safety of culvert structure.The author studied the embankment culvert from the angle of space by using three-dimensional finite element analysis method.Taking embankment slope as the starting point, this paper studies the variation of vertical soil pressure at the top of culvert under the condition of rigid foundation and soft foundation under different conditions of embankment slope.The main contents of this paper are as follows: (1) A three dimensional finite element model is established by using commercial software ANSYS.In the case of rigid foundation, the distribution of vertical earth pressure at the top of culvert under the condition of different slope, different fill height and different slope height is analyzed with box culvert as the research object.The results show that the earth pressure coefficients are all greater than 1, the stress concentration is obvious, the soil pressure coefficient increases first and then decreases with the increase of the filling height, the slope and the fill height are constant, the soil pressure coefficient increases first and then decreases with the increase of the filling height.With the increase of slope height, the soil pressure coefficient shows a nonlinear increasing trend, and the slope height is fixed, the larger the slope degree is, the larger the earth pressure coefficient is, and the difference is very small over this range.The vertical earth pressure at the top of the culvert increases with the filling height and the slope height increases with the increase of the height of the culvert.When the slope height and fill height are small, the soil pressure increases with the increase of slope, and when the slope height and fill height are larger, the soil pressure decreases with the increase of slope.In the case of rigid foundation, the variation law of vertical earth pressure coefficient with slope height and slope at the top of culvert section under road surface is analyzed, and the variation law of vertical soil pressure at the top of culvert at road middle line with slope height is analyzed.The results show that the vertical earth pressure at the top of culvert at the middle of the road increases with the increase of slope height, and the equation of unearthed pressure is quadratic polynomial.(3) in soft foundation, the distribution of soil pressure at the top of culvert under different slope and different fill height is analyzed with box culvert as the research object.Numerical simulation culvert construction process, that is, the process of layered fill.The variation trend of fill displacement under the interaction of culvert structure and soil is analyzed by comparing the numerical calculation of one-off fill.Research on theoretical formula of culvert system under slope.Combined with theoretical derivation and curve fitting, the nonlinear calculation formula of vertical earth pressure at the top of culvert is obtained by comparison and analysis, which is convenient for engineering reference.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U449

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