多层土工合成材料加筋路基沉降的数值分析

发布时间：2018-06-07 02:00

本文选题：土工加筋路基 + 沉降　；参考：《湘潭大学》2014年硕士论文

【摘要】：土工合成材料作为一种新型的岩土工程材料，已广泛应用于各个工程领域。目前对于土工合成材料加筋路基的理论研究与工程实践比相对滞后，如对加筋路基的沉降变形分析中，荷载在路基和地基中的传递扩散作用常常被忽略，且较少考虑筋材抗弯刚度及筋土界面软化-位移方面性质，导致理论计算结果与工程实际相差较大，限制了土工合成加筋材料的应用。本文主要研究内容和结论如下：（1）利用Ansys软件，建立了多层加筋路基平面应变模型，研究了路基的沉降变形。（2）采用Yin的基本假设和变形协调关系，并将软土地基简化为winkler弹簧，建立了一维加筋路基沉降变形微分方程。利用Mathematica符号解法，对方程进行了求解。（3）通过算例，将Mathematica符号解法计算结果与退化至单层加筋的有限元解进行对比，验证了符号解与有限元解的一致性。在有限元模拟中，研究了路基沉降变形特性，并进行了参数分析，结果表明，当路基填料弹性模量小于40MPa，筋材弹性模量小于20MPa时，两者对路基沉降的影响相对显著；而大于上述值时，影响会变得越来越有限。在实际工程运用中，可根据需要，应控制路基弹性模量和筋材模量在上述合理范围内，以实现最优的经济效果。在软土地基上，铺设土工合成加筋材料，加筋效果更为明显。（4）以模型实验数据为基础，利用Ansys软件，分别建立了桩承式加筋路基的平面应变模型和轴对称三维模型。平面模型中，桩体和桩间土采用不同弹性常数的弹簧单元模拟，大大减少了计算单元的数量；轴对称模型选取了中心桩及相邻桩间土四分之一部分建模。计算结果与实验数据的对比表明，两者之间具有良好的一致性。（5）基于两种桩承式加筋路基模型，，考察了路基顶面和桩顶平面位置沉降变形特性，并分析了各参数对路基沉降的影响，为桩承式加筋路基的优化设计提供了参考。参数分析表明，加筋层数对路基沉降变形影响不足1%，不建议采用增加层数的方法来控制路基沉降；桩反力系数在100kN/m3左右时可以取得最好的加筋效果；筋材的高度对路基沉降变形也有较大的影响。
[Abstract]:As a new geotechnical engineering material, geosynthetics have been widely used in various engineering fields. At present, the theoretical research of geo-composite material reinforced roadbed is lagging behind the engineering practice. For example, in the analysis of settlement and deformation of reinforced subgrade, the transfer and diffusion of load in subgrade and foundation are often neglected. Less consideration is given to the flexural stiffness of reinforced materials and the properties of softening and displacement of the interface between reinforcement and soil, which leads to a big difference between the theoretical calculation results and the engineering practice, which limits the application of geosynthetic reinforced materials. The main contents and conclusions of this paper are as follows: 1) using Ansys software, the plane strain model of multi-layer reinforced roadbed is established, and the settlement deformation of roadbed is studied. (2) based on the basic assumption of Yin and the compatibility of deformation, the differential equation of settlement and deformation of one-dimensional reinforced roadbed is established by simplifying the soft soil foundation to winkler spring. The equation is solved by Mathematica symbolic method. 3) the results of Mathematica symbolic solution are compared with the finite element solution which degenerates to single-layer reinforcement, and the consistency between the symbolic solution and the finite element solution is verified. In the finite element simulation, the characteristics of subgrade settlement and deformation are studied, and the results show that when the elastic modulus of subgrade filler is less than 40 MPA and the elastic modulus of reinforcement is less than 20MPa, the influence of them on subgrade settlement is relatively significant. And above the above value, the impact will become more and more limited. In practical engineering application, the elastic modulus of roadbed and the modulus of steel bar should be controlled within the above reasonable range according to the need, so as to realize the optimal economic effect. On the soft soil foundation, the reinforcement effect is more obvious when the geo-composite reinforcement material is laid. Based on the model experimental data, the plane strain model and axisymmetric three-dimensional model of pile-supported reinforced roadbed are established by using Ansys software. In the plane model, the spring element with different elastic constants is used to simulate the pile and the soil between the piles, which greatly reduces the number of calculation elements, and the axisymmetric model selects a quarter of the soil between the central pile and the adjacent pile to model the model. The comparison between the calculated results and the experimental data shows that there is a good agreement between the two. Based on two kinds of pile-supported reinforced roadbed models, the settlement and deformation characteristics of the top surface of the roadbed and the plane position of the pile-top are investigated, and the influence of various parameters on the settlement of the roadbed is analyzed, which provides a reference for the optimization design of the pile-supported reinforced roadbed. Parameter analysis shows that the effect of reinforcement layer number on subgrade settlement is less than 1, the method of increasing the number of layers is not recommended to control the subgrade settlement, the pile reaction coefficient can obtain the best reinforcement effect when the 100kN/m3 is about or so. The height of reinforcement also has great influence on subgrade settlement and deformation.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1

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