【作者】 梅英宝；

【导师】 朱向荣；

【作者基本信息】 浙江大学 ， 岩土工程， 2004， 博士

【摘要】 交通荷载作用下道路或机场跑道的沉降计算，是工程界普遍关心的问题，也是学术界长期以来的重点研究课题。受地理条件限制，很多高速公路和机场跑道建造在深厚软土地基上，而软土高压缩性、低强度等特点又难以满足工程对变形的严格要求，需要对软粘土进行处理构成复合地基，以减小地基沉降。车辆或飞机等交通荷载作用下，道路或机场跑道与地基是一共同作用、相互影响的有机整体，其共同作用变形特性，是一值得深入研究的课题。 本文首先介绍了软土地基和复合地基动力特性研究现状，从理论研究、试验模拟和数值分析三方面总结了道路与地基共同作用研究现状，接着概述了适合岩土材料的弹塑性本构理论和动态弹塑性有限元理论，叙述了总应力法和有效应力法动力分析的区别及适用性，然后概括了路面材料、软粘土和复合地基的动力特性。 总结了交通荷载特性及其研究现状，介绍了典型的道路结构特点。概括了软土地基和软土复合地基动孔压模型的研究现状，分别建立了动孔压经验模型，并且基于前人的室内动三轴试验结果确定了模型计算参数。 编制了动态弹塑性有限元分析程序，通过程序计算结果与解析解的对比分析，验证了本文程序的正确性，说明了采用有效应力法分析地基动力变形问题的必要性。程序在分析结构与土体动力相互作用时，可实现多种动力加载方式的模拟。 将交通荷载简化为半波正弦荷载，假定地基土体为硬化型土，运用本文编制的动态弹塑性有限元程序，分析了单次动力加载和循环动力加载条件下道路横截面与软土地基共同变形特性。分析了荷载因素(包括荷载类型、荷载幅值、荷载频率)和地基土体参数(包括回弹模量、内聚力、内摩擦角、泊松比、阻尼比)对变形的影响。采用本文建立的软土地基动孔压模型，对比分析了不排水有效应力法和总应力法计算结果，计算了残余孔隙水压力消散所产生的固结沉降，探讨了孔压对道路变形的影响。 运用本文编制的动态弹塑性有限元程序，计算分析了循环动力加载条件下道路横截面与复合地基及软土地基共同变形特性。采用本文建立的复合地基动孔压模型，详细分析了孔压、道路结构层参数、复合地基和软土地基各参数以及水平荷载对道路变形特性的影响。将交通荷载简化为移动的集中荷载，计算分析了单次移动加载和循环移动加载条件下道路纵截面与复合地基共同变形特交通荷载作用下道路与软土复合地基共同作用性状研究性，探讨了孔压、行车速度及道路结构层和地基参数对道路变形的影响。 最后，对某道路与软土地基横截面、某机场跑道与复合地基纵截面两工程实例进行了计算分析，结果表明，有限元计算沉降与工程实测沉降基本吻合。 本文建立了软土地基和复合地基的动孔压经验模型，编制了不排水有效应力动力反应分析有限元程序，不仅考虑了地基土体的弹塑性，而且考虑了道路结构与地基的相互作用，比较全面地分析了交通荷载作用下道路与地基的整体变形特性，对道路工程或机场道面工程的建设具有一定的指导意义。更多还原

【Abstract】 Settlement calculation of pavement or airport runway under traffic load is one of most concerned problems in engineering area, as well as a key subject in academic area. Limited by geographic conditions, many express highways and airport runways have to be built on thick soft soil foundation. For its high compressibility and low strength, soft soil should be improved by composite foundation technology to satisfy the strict requirement of deformation. Subjected to traffic load, the pavement and foundation should be taken as a whole system of interaction, and of which deformation characteristics are worth studying.Firstly, the paper introduced the present study state on dynamic characteristics of soft subgrade and composite foundation, generalized the present study state on interaction of pavement and foundation from theory study, experimental modeling and numerical analysis aspects. Subsequently, the theory of elasto-plastic constitute and dynamic finite element method(FEM) are summarized, the difference and applicability of total stress method and effective stress method are described. Then, dynamic features of pavement materials, soft soil and composite foundation are depicted simply.The features and present study state of traffic load are generalized, and the typical structure of pavement is introduced. Then the paper summarized the present study state on dynamic pore pressure model of soft subgrade and composite foundation, established empirical dynamic pore pressure model respectively, and the model parameters are obtained based on formers’ indoor dynamic triaxial tests.A dynamic elasto-plastic FEM program is compiled, and is verified by comparing the calculated results with analytical solutions. Many types of dynamic load can be used to analyze the problems of interaction of soils and structures with this program. And it is necessary to use effective stress method to study dynamic deformation problems of soil subgrade.For convenience, traffic load is simplified as half-sinusoidal load, and the soil of subgrade is assumed to be strain-hardening. The deformation characteristics of pavement section and soft soil subgrade under traffic load are analyzed, considering the effects of load (including type, amplitude and frequency) and parameters of soft soil (including resilient modulus, cohesion, internal friction angle, Poisson ratio, damping ratio et al). With the established dynamic pore pressure model, the calculated results of total stress method and effective stress method are compared. Consolidation settlement induced by dispersion of residual pore pressure is calculated, and the effect of pore pressure on pavement settlement is discussed.The deformation characteristics of pavement section and composite foundationunder cyclic traffic load are analyzed with the FEM program. With the dynamic pore pressure model of composite foundation established, the effects of pore pressure, horizontal load, parameters of pavement structure, soft subsoil and composite foundation on pavement deformation are discussed in detail. Taking the traffic load as moving point load, the deformation characteristics of longitudinal section of pavement and composite foundation under moving point load are analyzed, considering the effect of pore pressure, traffic velocity, parameters of pavement structure and subgrade.Finally, two examples of pavement section and soft subgrade, longitudinal section of airport runway and composite foundation are calculated. And the results show that the calculated settlement agree well with that of measured.The paper established the dynamic pore pressure models of soft soil subgrade and composite foundation, compiled the dynamic FEM program of undrained effective stress method, considering the elasto-plasticity of foundation soil as well as the interaction of pavement and foundation, thoroughly analyzed the deformation characteristics of pavement and foundation, and these results are instructive for the construction of pavement or airport runway.更多还原