穿越黄土填方区域埋地管线变形特性研究

发布时间：2018-03-24 13:38

本文选题：黄土　切入点：填方区域　出处：《西安科技大学》2017年硕士论文

【摘要】：在我国沟壑纵横的黄土高原地区城市化进程中,黄土填方是必不可少的一种典型而又普遍的工程措施。填方土体不均匀沉降必然会导致穿越填方区管线出现变形甚至破坏,因此研究穿越黄土填方区域埋地管线变形特性很有必要。以延安某填方区直埋管线为研究对象,通过收集资料及现场调查,归纳填方区域沉降特征,总结管线的变形模式,建立力学模型,得出管线力学变形破坏机制。分别对穿越不同形式填方区域管线开展室内模型试验,得到填方土体不均匀沉降差时管线位移、应变以及下部土压力的变化规律。最后,通过MIDAS软件进行数值模拟,进一步研究穿越黄土填方区域埋地管线变形特性。研究取得如下成果:(1)通过现场调查,归纳填方区域沉降形式有:填方“斜线形”沉降形式、填方“凸形”沉降形式、填方“凹形”沉降形式以及三种的组合形式。(2)提出穿越填方区域埋地管线的变形模式:剪切变形模式、撬曲变形模式、梁式受压变形模式、扭转变形模式以及受压失稳变形模式。(3)通过穿越填方“斜线形”沉降区域管线模型试验得出,随填方土体沉降,管线最大位移发生在填方沉降区域距离不均匀沉降面最远端;不均匀沉降面处管线位移变化幅度较大,管线沉降位移曲线整体呈“S”形变化。管线上表面在整个试验过程中均受拉应力影响,不均匀沉降面处拉应力最大,填方沉降区拉应力最小。管线下部土压力在不均匀沉降面处减小幅度最大,填方沉降区管线处于悬空状态。该模式下管线的变形主要为撬曲变形模式。(4)通过穿越填方“凸形”沉降区域管线模型试验,随填方土体沉降,管线最大位移发生在两侧填方沉降区管线端部;不均匀沉降面处管线位移变化幅度较大,管线沉降曲线整体以填方相对稳定区中点呈抛物线形状。管线上表面应变值在两侧填方沉降区为负值,中间填方相对稳定区为正值;管线应变最大值发生在模型中间填方相对稳定区中点,且呈对称分布。管线下部土压力在不均匀沉降面处减小幅度最大,管线在两侧填方沉降区域处于悬空状态。(5)通过穿越填方“凹形”沉降区域管线模型试验,随填方土体沉降,管线最大位移发生在模型中间填方沉降区中点;不均匀沉降面处管线位移变化幅度较大,管线沉降曲线整体以填方沉降区中点呈抛物线形状。管线上表面应变值在填方沉降区为负值,两侧填方相对稳定区为正值;管线应变最大值发生在填方沉降区中点,且呈对称分布。管线下部土压力在不均匀沉降面处减小幅度最大,在沉降过程中,管线在填方沉降区域处于悬空状态。
[Abstract]:Loess fill is a typical and universal engineering measure in the urbanization process of gully and horizontal loess plateau in our country. Uneven settlement of fill soil will inevitably lead to deformation and even destruction of pipeline crossing the fill area. Therefore, it is necessary to study the deformation characteristics of buried pipeline in the loess filling area. Taking the buried pipeline in a certain filling area in Yan'an as the research object, the settlement characteristics of the filling area are summed up by collecting data and field investigation, and the deformation mode of the pipeline is summarized. The mechanical model was established and the mechanical deformation failure mechanism of pipeline was obtained. Indoor model tests were carried out on the pipeline through different types of filling area, and the pipeline displacement was obtained when the uneven settlement of fill soil was different. Finally, through the numerical simulation of MIDAS software, the deformation characteristics of buried pipeline through loess fill area are further studied. The research results are as follows: 1) through field investigation, The regional settlement of the fill is summarized as follows: the settlement form of the filling is "inclined line", the form of settlement of the filling is "convex", The "concave" settlement form of the fill and three kinds of combination form. 2) proposed the deformation mode of the buried pipeline through the filling area: shear deformation mode, pry deformation mode, beam compression deformation mode, Torsional deformation mode and compression instability deformation mode. 3) through the pipeline model test of "inclined line" settlement area, it is concluded that the maximum displacement of pipeline occurs at the farthest end of the uneven settlement surface with the settlement of the fill soil. The displacement of pipeline at uneven settlement surface is larger, and the displacement curve of pipeline is "S" shape. The upper surface of pipeline is affected by tensile stress in the whole process of test, and the tensile stress at uneven settlement surface is the largest. The tensile stress in the settlement area of the fill is the smallest, and the earth pressure in the lower part of the pipeline decreases the most at the uneven settlement surface. The pipeline in the settlement area is in a suspended state. The deformation of the pipeline is mainly pry deformation mode. 4) through the model test of pipeline passing through the "convex" settlement area of the fill, the settlement of the soil is accompanied by the settlement of the soil. The maximum displacement of the pipeline occurs at the end of the pipeline in the settlement area of both sides of the fill, and the displacement of the pipeline varies greatly at the uneven settlement surface. The settlement curve of pipeline takes the shape of parabola at the middle point of the relative stable region of the fill. The strain value of the surface of the pipeline is negative in the settlement area of both sides of the fill, and the relative stable zone of the intermediate filling is positive. The maximum strain of pipeline occurs at the middle point of the relative stable region in the middle of the model, and the distribution is symmetrical, and the earth pressure of the lower part of the pipeline decreases the most at the uneven settlement surface. The pipeline is suspended in the settlement area of both sides of the fill.) through the model test of pipeline passing through the "concave" settlement area of the fill, the maximum displacement of the pipeline occurs in the middle of the settlement area of the model with the settlement of the filling soil. The displacement of pipeline varies greatly at uneven settlement surface. The whole settlement curve of pipeline is parabola shape in the middle of the settlement area. The strain value of the upper surface of the pipeline is negative in the settlement area of the filling, and the relative stable region of the two sides of the fill is positive. The maximum strain of pipeline occurs at the midpoint of the settlement area and is symmetrical distributed. The earth pressure of the lower part of the pipeline decreases the most at the uneven settlement surface. In the process of settlement, the pipeline is suspended in the settlement area of the fill.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU990.3

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