下卧海相沉积软土环境下深基坑开挖变形特性及控制研究

发布时间：2018-05-27 22:01

本文选题：海相沉积软土 + 深基坑　；参考：《重庆大学》2016年硕士论文

【摘要】：在我国沿海地区广泛分布着深厚的第四纪海相沉积软土层。该软土层具有高孔隙比、高压缩性等物理力学性质,极易导致基坑周边土体出现变形过大的问题。不同沉积环境下的软土,其变形特性各不相同,甚至相差甚远。目前学者们对软土深基坑的变形问题已进行了较为丰富的研究,但针对下卧海相沉积软土环境下的深基坑变形问题的研究相对较少。预测下卧海相沉积软土环境下深基坑工程开挖引起的变形,总结下卧海相沉积软土环境下深基坑工程变形的控制措施,对于该环境下深基坑工程的设计和施工具有一定程度的指导意义。论文结合深圳地区某深基坑工程实例,采用理论分析、室内试验和数值模拟相结合的研究方法,对下卧海相沉积软土环境下深基坑工程开挖引起的变形及变形控制措施进行了研究。论文所做的主要工作和得到的主要结论如下:(1)选用修正剑桥模型作为海相沉积软土的本构模型,通过室内三轴试验测定了深圳地区典型海相沉积软土的修正剑桥模型参数。通过FLAC3D数值模拟软件对深圳地区某深基坑工程实例进行了数值模拟分析。其中,海相沉积软土分别采用修正剑桥模型和摩尔库伦模型,其它地层采用摩尔库伦模型。将计算结果与现场监测数据进行对比,分析了下卧海相沉积软土环境下深基坑工程的变形特性。(2)基于深圳地区某深基坑工程实例,采用数值分析的方法研究了不同设计因素和施工因素对变形的影响,并对各因素进行了敏感性分析,在此基础上结合前人的研究成果归纳总结了下卧海相沉积软土环境下深基坑工程的变形控制措施。考虑到在以往关于深基坑变形的数值模拟分析中,其计算模型大多采用简化的二维模型,忽略了复杂的边界条件对变形的影响。本文采用三维模型进行计算分析,更为接近基坑开挖的实际情况,在理论上更具合理性。
[Abstract]:The deep Quaternary marine sedimentary soft soil layer is widely distributed in the coastal areas of China. The soft soil layer has the physical and mechanical properties such as high void ratio and high compressibility, which can easily lead to the problem of excessive deformation of soil around the foundation pit. The deformation characteristics of soft soil in different sedimentary environments are different or even very different. At present, scholars have done a lot of research on the deformation of deep foundation pit in soft soil, but there are few researches on the deformation of deep foundation pit in the environment of lying marine sedimentary soft soil. The deformation caused by the excavation of deep foundation pit under the environment of lying marine sedimentary soft soil is predicted, and the control measures for the deformation of deep foundation pit under the environment of lying marine sediment soft soil are summarized. It has certain guiding significance for the design and construction of deep foundation pit engineering in this environment. In this paper, a deep foundation pit project in Shenzhen area is studied by theoretical analysis, laboratory test and numerical simulation. The deformation and deformation control measures caused by deep foundation pit excavation under the environment of lying marine sedimentary soft soil are studied. The main work and conclusions are as follows: 1) the modified Cambridge model is chosen as the constitutive model of marine sedimentary soft soil, and the parameters of modified Cambridge model of typical marine sedimentary soft soil in Shenzhen area are measured by laboratory triaxial test. The numerical simulation analysis of a deep foundation pit project in Shenzhen area was carried out by using FLAC3D numerical simulation software. Among them, the modified Cambridge model and the Moore Coulomb model are used in the marine sedimentary soft soil, and the Moore Coulomb model is used in the other strata. By comparing the calculation results with the field monitoring data, the deformation characteristics of deep foundation pit engineering under the environment of lying marine sedimentary soft soil are analyzed. The deformation characteristics of deep foundation pit engineering are analyzed based on an example of deep foundation pit engineering in Shenzhen area. The influence of different design factors and construction factors on deformation is studied by numerical analysis, and the sensitivity of each factor is analyzed. On this basis, the deformation control measures of deep foundation pit engineering under the environment of lying marine sedimentary soft soil are summarized and summarized in combination with the previous research results. Considering that in the previous numerical simulation analysis of deep foundation pit deformation, most of its calculation models are simplified two-dimensional model, ignoring the influence of complex boundary conditions on deformation. In this paper, 3D model is used to calculate and analyze, which is closer to the actual situation of foundation pit excavation and is more reasonable in theory.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU753

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