液化场地中埋地管线的形变特征

发布时间：2018-10-24 22:43

【摘要】：砂土液化是地震中一种常见的土体破坏形式,其造成的土体大变形和巨大的上浮压力是埋地管线系统最危险的破坏因素。因此,研究埋地管线抵御砂土液化设计理论和方法是确保其在液化场地中的安全至关重要一环。基于液化时巨大的砂土上浮力和液化后土体沉降两种最常见的现象,本文探究了连续管线和带有橡胶圈柔性接头的非连续管线在这两种工况下的形变特征,为合理设计埋地管线的抗液化措施提供可靠指导。本文的主要工作和研究结果概况如下:1.基于ANSYS平台,建立非液化土体与管线的非线性接触模型、液化区土体与管线间的土体弹簧模型,系统分析了连续管线和非连续管线在液化土体中的应力分布和形变特征。结果表明,考虑管线与土体相互作用时,液化区的土弹簧模型和非液化的非线性接触模型能合理模拟管土相互作用规律。2.建立了连续管线和带有橡胶圈柔性接头的非连续管线在液化场地下的上浮模型,考虑土体和管材的材料非线性以及管线发生大变形时的几何非线性,用壳体单元模拟管线,弹簧单元模拟橡胶圈柔性接头。结果显示,连续管线最危险的位置为液化与非液化土体的相交处以及液化区中间位置,液化区范围是影响连续管线上浮的关键因素,因而可以通过控制连续管线在液化区中的间隔防止管线破坏;非连续管线的上浮位移比连续管线大得多,应力主要集中在接头位置附近,上浮位移、接头最大转角以及接头最大拔出长度会随着液化区接头数量的增多而增大。3.建立了连续管线和非连续管线在液化后土体沉降的分析模型。比较不同土质下连续管线和非连续管线的反应,发现非液化土体刚度较小时,非连续管线通过接头的转动可以吸收较大的液化沉降位移而不发生破坏。非液化土体刚度较大时,非连续管线较连续管线更容易发生管体压缩破坏,减小沉降交界处管段长度是防止管体破坏的有效措施。
[Abstract]:Sand liquefaction is a common form of soil failure in earthquake. The large deformation of soil and the huge floating pressure are the most dangerous failure factors in buried pipeline system. Therefore, it is very important to study the theory and method of sand liquefaction design for buried pipeline in order to ensure its safety in liquefaction site. Based on the two most common phenomena during liquefaction, the buoyancy of sand and the settlement of soil after liquefaction, the deformation characteristics of continuous pipeline and discontinuous pipeline with flexible joint of rubber ring under these two conditions are investigated in this paper. It provides reliable guidance for rational design of anti-liquefaction measures of buried pipeline. The main work and results of this paper are summarized as follows: 1. Based on the ANSYS platform, the nonlinear contact model between non-liquefaction soil and pipeline, and the soil spring model between liquefaction soil and pipeline are established. The stress distribution and deformation characteristics of continuous pipeline and discontinuous pipeline in liquefaction soil are analyzed systematically. The results show that the soil-spring model and the non-liquefaction nonlinear contact model can reasonably simulate the pipe-soil interaction law when the interaction between pipeline and soil is considered. The floating model of continuous pipeline and discontinuous pipeline with rubber ring flexible joint in liquefaction field is established. Considering the material nonlinearity of soil and pipe and the geometric nonlinearity of pipeline in large deformation, the pipeline is simulated by shell element. Spring element simulates rubber ring flexible joint. The results show that the most dangerous position of continuous pipeline is the intersection of liquefaction and non-liquefaction soil and the middle position of liquefaction zone. The range of liquefaction zone is the key factor affecting the floating of continuous pipeline. Therefore, the failure of the pipeline can be prevented by controlling the spacing of the continuous pipeline in the liquefaction zone. The floating displacement of the discontinuous pipeline is much larger than that of the continuous pipeline, and the stress is mainly concentrated near the joint position. The maximum angle and the maximum pull-out length of the joint will increase with the increase of the number of joints in the liquefaction zone. An analytical model of soil settlement after liquefaction of continuous pipeline and discontinuous pipeline is established. By comparing the reaction of continuous pipeline and discontinuous pipeline under different soil quality, it is found that when the stiffness of non-liquefaction soil is relatively small, the discontinuous pipeline can absorb larger liquefaction settlement displacement without destruction through the rotation of joint. When the stiffness of non-liquefaction soil is large discontinuous pipeline is more prone to pipe compression failure than continuous pipeline. Reducing the length of pipe section at the settlement junction is an effective measure to prevent pipe body damage.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU435;TU990.3

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