泡沫轻质土用于软基上高速公路扩建工程的受力与变形特性分析

发布时间：2018-02-27 13:29

本文关键词： 高速公路拓宽工程泡沫轻质土弹塑性有限元分析软土地基硬壳层效应有限元强度折减塑性区贯通　出处：《河北工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：针对东南沿海地区软土地基上的高速公路拓宽工程,通过分析其病害机理及不协调变形的控制手段,结合目前广泛推广采用的轻质填料,提出应转变处理角度:从提高拓宽路基下软基的承载力或固结度转变为降低其上覆附加荷载,以期通过控制拓宽路基填料的性质来减小对软基的处理强度并合理优化挡墙结构。本文以唐津高速扩建工程为研究载体,结合现场对泡沫轻质土拓宽路基的土压力实际监测与有限元数值模拟分析,从以下几方面进行了重点研究:首先,对泡沫轻质土的主要物理力学指标特性及其工程应用机理进行总结分析,并结合有效应力原理及硬壳层效应对软基固结沉降的控制措施进行原理性探究,且重点研究了泡沫轻质土用于软基上路基拓宽的力学机理,明确指出土工合成材料用于板体性轻质土拓宽衔接时应着重考虑的因素。其次,从岩土材料产生塑性变形的内在机制出发研究其区别于金属材料的弹塑性理论,并根据泡沫轻质土的力学特性指出其对DP理想弹塑性模型的适用性。结合路基拓宽的施工阶段影响及轻质土本身的施工特点,利用旧路基及地基自重荷载产生的初应力场施加及旧路边坡开挖、轻质土分层浇筑的单元生死技术,对轻质土拓宽路基在施工过程中及不同拓宽断面尺寸下的应力响应进行非线性结构分析,提出了轻质土板体在浇筑层间及基底处类似于刚性基础的传力机制,并结合硬壳层效应及轻质土荷载分布特点对拓宽路基不同位置处的位移发展趋势进行探索,以明确轻质土拓宽路基的受力薄弱区及位移发展集中区。最后,通过强度折减原理,对轻质土拓宽路基的整体稳定性进行分析,从轻质土的材料参数、软基的抗剪强度、硬壳层三个因素探究其对拓宽后路基整体的塑性区贯通、侧向位移发展的影响,并重点对比研究了高窄型与低宽型拓宽路基的塑性区形成特点及失稳破坏机理,从而指导拓宽时轻质土材料设计参数的调整、土工材料衔接处理的重要位置确定及软基的针对性加固。
[Abstract]:Aiming at the expressway widening project on soft soil foundation in southeast coastal area, through analyzing the disease mechanism and the control means of uncoordinated deformation, combining with the light packing widely used at present, It is proposed that the angle of treatment should be changed: from increasing the bearing capacity or consolidation degree of soft foundation under widening roadbed to reducing the additional load on top of it, In order to reduce the treatment strength of soft foundation and optimize the structure of retaining wall by controlling the property of widening the filling of roadbed, this paper takes Tangjin high-speed expansion project as the research carrier, Combined with the field monitoring and finite element numerical simulation analysis of the earth pressure of the foamed lightweight soil widening roadbed, the following aspects are emphatically studied: first of all, The main physical and mechanical properties of foamed light soil and its engineering application mechanism are summarized and analyzed, and the control measures of consolidation settlement of soft foundation are studied by combining the effective stress principle and the effect of hard shell layer. The mechanical mechanism of foam lightweight soil used for roadbed widening on soft foundation is emphatically studied, and the factors that should be considered when geosynthetics are used in widening of plate lightweight soil are pointed out. Secondly, Based on the inherent mechanism of plastic deformation of geotechnical materials, the elastic-plastic theory, which is different from metal materials, is studied. According to the mechanical characteristics of foamed lightweight soil, the applicability of this model to DP ideal elastoplastic model is pointed out, which is combined with the influence of roadbed widening in construction stage and the construction characteristics of lightweight soil itself. The unit life and death technique is used to apply the initial stress field caused by the old roadbed and the deadweight load of the foundation, and excavate the slope of the old road, and the light-weight soil is poured into layers. The nonlinear structural analysis of the stress response of lightweight soil widening roadbed during construction and under different widening section sizes is carried out, and a force transfer mechanism similar to that of rigid foundation is put forward, which is similar to that of rigid foundation. Combined with the effect of hard shell and the characteristics of load distribution of lightweight soil, the development trend of displacement at different positions of widening roadbed is explored, in order to make clear the weak area of stress and the concentrated area of displacement development in widening roadbed of light soil. Finally, through the principle of strength reduction, Based on the analysis of the overall stability of the light soil widening roadbed, the effects of the material parameters of the light soil, the shear strength of the soft foundation and the hard shell layer on the overall plastic zone and lateral displacement development of the roadbed after widening are discussed. The forming characteristics of plastic zone and failure mechanism of high narrow and low width widening roadbed are compared and studied so as to guide the adjustment of design parameters of lightweight soil material. The important position of joint treatment of geotechnical materials and the targeted reinforcement of soft foundation are determined.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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