黄土地区SMW工法基坑围护结构设计理论与变形规律研究

发布时间：2018-07-07 16:50

本文选题：黄土地区 + SMW工法　；参考：《西安科技大学》2017年硕士论文

【摘要】：本文通过型钢-水泥土组合梁试验,研究了型钢与水泥土共同作用关系、加载过程中组合梁的抗弯刚度变化规律、组合梁的抗弯承载力和破坏模式等问题;基于弹性支点法给出了基坑支护结构的位移及内力计算公式,并将西安某基坑支护工程实例的理论计算结果与FLAC3D模拟及现场实测结果进行了对比,研究了黄土地区SMW工法基坑围护结构设计理论与变形规律。论文的主要工作与结论如下:(1)通过型钢-水泥土组合梁的试验研究可以得出以下结论:组合梁工作过程经历共同作用、型钢单独作用两个阶段,组合梁在不同阶段裂缝开展、型钢应变变化及组合刚度的变化表现出显著的差异;不同的受力状态下组合梁的刚度、承载力及破坏性状存在较大差异。水泥土的包裹作用有利于对组合梁中型钢的稳定和承载性能的发挥,使组合梁表现出较好的延性,水泥土对型钢的约束作用越强其承载力和变形能力越强;在进行实际工程设计计算时当墙体变形较小,水泥土较完整对组合结构刚度提高作用较大,可采用本文给出的公式进行组合梁刚度计算;当墙体变形较大时,水泥土开裂严重退出工作,由型钢单独承担荷载此时不应考虑水泥土的贡献。(2)基于弹性支点法并结合结构水平位移叠加原理,给出了支护位移及内力计算公式,并对西安某基坑工程实例进行了计算,结果表明:计算与实测的支护结构水平位移均呈“S形”发展,本文计算方法所得到的支护结构水平位移规律可为类似工程设计提供参考。(3)以西安某深基坑工程为背景,采用FLAC3D数值模拟软件,分析了基坑各开挖工况下水平位移变化规律并与实际监测数据进行对比,得到两者变化规律相似。另外分析了基坑的周边环境沉降及基底隆起规律发现:基坑周边沉降出现出现“勺状”分布,最大的沉降值并非发生在基坑边缘,沉降量和影响范围均较小;在整个开挖过程基底坑底隆起量较小,表明围护桩对桩后土体的变形有较大的限制,研究结论对黄土地区SMW工法设计施工有借鉴意义。
[Abstract]:In this paper, through the test of steel cement soil composite beam, the joint action relation of type steel and cement soil, the change law of bending stiffness of composite beam, bending bearing capacity and failure mode of composite beam during loading process are studied, and the calculation formula of displacement and internal force of foundation pit supporting structure is given based on elastic branch method, and a foundation pit branch in Xi'an is used. The theoretical calculation results of the case of the protection engineering are compared with the FLAC3D simulation and the field measured results. The design theory and deformation law of the foundation pit enclosure structure in the loess area are studied. The main work and conclusion of the paper are as follows: (1) the following conclusions can be obtained by the experiment of the steel cement soil composite beam through the model: the working process of the composite beam can be obtained. As a result of the joint action, the type steel has two stages separately. The composite beam is carried out in different stages, the strain change and the combination stiffness change significantly. The stiffness, bearing capacity and failure characteristics of the composite beams are different. The wrapping effect of cement soil is beneficial to the stability of the medium steel. The combination beam shows better ductility. The stronger the binding effect of the cement soil to the type steel, the stronger its bearing capacity and the deformation ability. In the actual engineering design calculation, when the wall deformation is small, the cement soil is more complete to the composite structure stiffness, and the formula given in this paper can be used to carry on the composite beam. Stiffness calculation; when the wall deformation is large, the cracking of cement soil is seriously out of work, and the contribution of cement soil should not be considered at this time. (2) the calculation formula of support displacement and internal force is given based on the elastic fulcrum method combined with the superposition principle of structural horizontal displacement, and the results of a foundation pit project in Xi'an are calculated and the results are calculated. The results show that both the calculated and measured horizontal displacement of the supporting structure are "S". The horizontal displacement law of the supporting structure obtained by this method can provide reference for similar engineering design. (3) taking a deep foundation pit in Xi'an as the background, the FLAC3D numerical simulation software is used to analyze the change law of horizontal displacement under each excavation condition of the foundation pit. And compared with the actual monitoring data, it is found that the law of the two changes is similar. In addition, it is found that the surrounding settlement of the foundation pit and the regularity of the basement uplift found that the "spoon" distribution appears in the surrounding settlement of the foundation pit, and the maximum settlement value is not on the edge of the foundation pit, the settlement amount and the influence range are small, and the foundation pit in the whole excavation process is in the base pit. The bottom uplift is small, which indicates that the retaining piles have great limitations on the deformation of the soil behind the pile. The research conclusions can be used for reference in the design and construction of the SMW method in the loess area.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU444;TU473

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