【作者】 杨晓东；

【导师】 时刚；

【作者基本信息】 郑州大学 ， 建筑与土木工程（专业学位）， 2018， 硕士

【摘要】 随着我国城市化进程的加速,传统的多层建筑已经不能满足人们日益增长的需求,城市建设开始向高层建筑、超高层建筑和地下空间发展,对基坑支护的要求也越来越高。在此背景下,基坑工程及其相关技术迅速发展起来。本文引入一种内插预应力钢管混凝土桁架的水泥土围护桩,这是一种新型的组合结构形式,与一些传统的基坑支护方式相比,具有施工速度快、抗渗性能好等优点,能够提高施工功效,降低维护成本并且更加绿色环保。本文主要针对预应力钢管桁架水泥土组合梁的刚度、变形等受力性能进行研究,采用室内模型试验与有限元数值模拟相结合的手段,采用模型实测结果对有限元模型进行校验,通过数值模拟对预应力钢管桁架水泥土组合梁结构的性能进行详细的分析。本文完成的主要工作有:1.进行了两组普通钢管桁架与预应力钢管桁架的静力加载对比试验,研究了两种钢管桁架的刚度、变形和承载力等受力性能。试验结果表明:对钢管桁架施加预应力后,不仅可以提升钢管桁架的抗弯刚度,并可有效调节杆件的应力分布,杆件的受力性能得到了很大的改善。2.开展了水泥土各项物理性能和力学性能的试验研究;通过无侧限压缩试验、三轴压缩试验等得出了不同掺入比的水泥土的变形模量、内摩擦角以及粘聚力等参数,分析总结了龄期和水泥掺入比对水泥土强度变化的影响,为水泥土组合梁的有限元模拟提供了相关参数。3.进行了预应力钢管桁架水泥土组合梁进行静力加载试验,研究水泥土组合梁的整体刚度、变形和裂缝的分布情况,并与预应力钢管桁架进行了对比,探讨水泥土与预应力钢管桁架的相关作用。研究结果表明,水泥土能够有效提升桁架构件的受力性能和整体刚度,而预应力钢管桁架能很好的延缓水泥土裂缝的发展。4.采用有限元方法对预应力钢管桁架和预应力钢管桁架水泥土组合梁进行了模拟和分析计算,通过与试验数据对比对有限元计算模型进行了校验,对影响预应力钢管桁架水泥土组合梁力学性能的主要因素进行了参数分析。分析结果表明:预应力钢管桁架结构的整体刚度主要受钢管强度、预应力的双重影响;其中,上下弦杆影响较小,预应力取值和腹杆特性的影响较为明显。预应力钢管桁架水泥土组合梁的整体刚度除了受上述因素影响还要受到水泥土力学性能的影响,并且水泥土力学性能对组合梁整体刚度的影响比较显著。更多还原

【Abstract】 With the acceleration of urbanization in China,traditional multi-story buildings have not been able to meet the growing needs of people.Urban construction has started to develop into high-rise buildings,super high-rise buildings and underground spaces,and the requirements for supporting foundation pits are also increasing.This paper introduces a cement soil enclosure pile with prestressed concrete filled steel tube truss,which is a new type of composite structure.Compared with some traditional foundation pit supporting methods,it has the advantages of fast construction speed and good seepage resistance,which can improve the construction efficiency,reduce the maintenance cost and be more green.This paper mainly studies the mechanical properties of prestressed steel tubular trussed cement-soil composite beams such as stiffness and deformation,and uses the combination of indoor model test and finite element numerical simulation.The finite element model is verified by the measured results of the model.In this thesis,the main completed tasks and conclusions are as the followings:1.Completed static loading tests on 2 sets of steel pipe trusses and 2 sets of prestressed steel pipe trusses.Through the tests,the steel pipe trusses and the prestressed steel pipe trusses are compared in mechanic performance,rigidity,deformation,and moment capacity,etc.The test results show that the prestressed steel truss can not only improve the bending stiffness of the steel tube truss,but also effectively regulate the stress distribution of the rod,and the force performance of the rod is greatly improved.2.Carried out experimental research on various physical and mechanical properties of cement soil.Through the unconfined compression test and triaxial compression test,parameters such as deformation modulus,internal friction angle,and cohesive force of cement-mixed soil with different incorporation ratios were obtained.The influence of age and cement mixing ratio on the strength change of cement soil was analyzed and summarized,and the relevant parameters were provided for finite element simulation of cement-soil composite beams.3.The preloaded steel-concrete-truss cement-soil composite beam was subjected to a static loading test to study the overall rigidity,deformation and crack distribution of the cement-soil composite beam.And compared with the prestressed steel pipe truss,the related role of cement soil and prestressed steel pipe truss was discussed.The research results show that cement soil can effectively improve the performance of the truss members and the overall stiffness,while the prestressed steel pipe truss can well delay the development of cement-soil cracks.4.Used ABAQUS to simulate and analyze the steel tube truss and prestressed steel tube truss cement soil composite beam.Verification of the finite element calculation model by comparison with test data.Analysis of the main factors affecting the mechanical properties of prestressed steel tubular trussed cement-soil composite beams The analyzed results showed that: the overall stiffness of the prestressed steel tube truss structure is mainly affected by the strength and prestress of the steel tube.Among them,the influence of the upper and lower chords is small,and the influence of the prestress value and the characteristics of the webbing are more obvious.The overall stiffness of prestressed steel tubular trussed cement-soil composite beams is affected not only by the above factors but also by the mechanical properties of cement-soil,and the mechanical properties of cement-soil have a significant effect on the overall stiffness of composite beams.更多还原