高加筋土挡墙的试验及数值分析研究

发布时间：2018-09-13 10:42

【摘要】：土工合成材料作为一种加筋材料被广泛应用在基础、边坡、道路等工程中，对边坡灾害的防治具有特殊效果，但加筋机制和设计理论方面的研究却落后于工程实际，从而影响加筋技术的发展。本文以神农架机场I边坡高加筋土挡墙为主要研究对象，通过室内拉拔试验，对土工格栅与碎石土的界面特性进行了深入研究，并通过Plaxis建立神农架机场I边坡高加筋土挡墙数值模型，，对不同施工阶段的挡墙进行数值分析，取得如下主要成果： 1）对高密度聚乙烯格栅HDPE130、HDPE170两种土工格栅与碎石土的界面特性进行拉拔试验，分析了不同上覆荷载下及不同拉拔位移时筋材的变形与刚体平动过程，研究了界面摩阻力渐进发挥及非均匀性变化过程，以及在不同上覆荷载情况下，筋带的似摩擦系数的变化规律，和残余摩擦系数在高上覆荷载下的主导作用。 2）假设土体为理想的Mohr-Coulomb弹塑性模型，通过Plaxis岩土有限元分析软件建模拟不同阶段挡墙的应力-应变情况，运用强度折减法模拟分析挡墙的潜在滑动面位置和安全系数，研究土工格栅加筋土挡墙三种破坏模式，并发现加筋土内部滑动面一般始于各级挡墙的坡脚，而加筋土外部，挡墙被视为一个整体，滑动面符合朗肯土压力理论。 3）高加筋土挡墙中未加筋土部分及加筋土部分不同断面的水平位移分布及挡墙在垂直面上最大位移的分布位置规律，发现加筋抑制土体的应变，导致筋材末端与未加筋土接触的位置，因土体的应变差异而产生剪应力集中。 4）数值计算模型基于传统的Mohr-Coulomb准则，所得数值计算结果普遍大于实际观测数据，说明Mohr-Coulomb准则并不能完全准确的反应筋-土的特征，因此使用Mohr-Coulomb准则计算加筋土时有一定的局限性。
[Abstract]:As a reinforced material, geosynthetics have been widely used in foundation, slope, road and other projects, which have special effects on slope disaster prevention, but the research on reinforcement mechanism and design theory lags behind the engineering practice. This affects the development of reinforcement technology. Taking the high reinforced earth retaining wall of Shennongjia Airport I slope as the main research object, the interfacial characteristics of the geogrid and the gravel soil are studied deeply through the indoor pull-out test. The numerical model of high reinforced earth retaining wall of Shennongjia Airport I slope is established by Plaxis, and the numerical analysis of retaining wall in different construction stage is carried out. The main results are as follows: 1) the interface characteristics of the two geogrid and gravel soil in HDPE grille HDPE130,HDPE170 are tested by pull-out test. The deformation and rigid body translational processes of steel bars under different overburden loads and different drawing displacements are analyzed, and the progressive exertion of interfacial friction resistance and the variation process of inhomogeneity are studied, as well as under different overburden loads. The variation law of the similar friction coefficient of the steel strip and the dominant effect of the residual friction coefficient on the high overburden load. 2) assuming that the soil is an ideal Mohr-Coulomb elastoplastic model, The stress-strain situation of retaining wall at different stages is simulated by Plaxis software, and the potential sliding surface position and safety factor of retaining wall are simulated by strength reduction method, and three failure modes of geogrid reinforced earth retaining wall are studied. It is also found that the internal sliding surface of reinforced earth usually begins at the slope foot of the retaining wall at all levels, and outside the reinforced earth, the retaining wall is regarded as a whole. The sliding surface accords with Rankine earth pressure theory. 3) horizontal displacement distribution of different sections of unreinforced soil and reinforced earth in high reinforced earth retaining wall and the distribution of maximum displacement of retaining wall on vertical plane. It is found that reinforcement inhibits the strain of soil and results in the position of contact between the end of reinforcement and unreinforced soil. 4) the numerical model is based on the traditional Mohr-Coulomb criterion. The numerical results obtained are generally larger than the observed data, which indicates that the Mohr-Coulomb criterion can not completely reflect the characteristics of the reinforced soil. Therefore, the use of the Mohr-Coulomb criterion in the calculation of reinforced soil has some limitations.
【学位授予单位】：长江科学院
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU476.4

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