软土的蠕变对深基坑变形的影响分析

发布时间：2018-06-21 11:43

本文选题：深基坑 + 蠕变　；参考：《武汉轻工大学》2013年硕士论文

【摘要】：随着我国改革开放的不断深入，我国的经济建设迅猛发展，城市建设中高层、超高层的建筑日益增多，这使得岩土深基坑支护成了热门。基坑工程的支护结构、开挖方案和土的蠕变特性都将会对基坑变形控制造成影响，从而进一步影响到基坑的安全性。本文分析了目前基坑设计中常用的弹性抗力法计算过程。该方法以弹性理论为基础，在土压力计算中，关键参数m值的确定依赖于工程与个人经验，参数的取值无法考虑基坑软土的蠕变特性，可能存在较大误差。因此，，对于含有流变特性地层的基坑支护工程，需要使用有限元方法验证设计方案。本文研究了岩土工程中常见的本构模型与蠕变模型后，以武汉某深基坑工程为例，对使用传统设计方法设计的基坑支护方案，采用有限元计算软件ABAQUS来模拟验算。在模拟开挖过程时，引入考虑了软土塑性与蠕变相耦合的Drucker－Prager模型来模拟场地内淤泥质粉质粘土。该计算模型考虑了软土的蠕变特性，分析计算结果后得到了基坑侧壁变形的蠕变规律。通过分析基坑开挖过程中的变形监测数据，得出了SMW工法桩在实际工程中的变形特点。再将有限元法的模型计算结果与实际监测结果对比，结果显示变形数据基本吻合，从而验证了基坑有限元计算模型的假设与计算的合理性。最后，根据基坑变形蠕变特点，改进了的基坑支护的方式，将改进支护方案有限元模型计算结果与原方案的结果对比，得到了基坑周围土体与支护结构的应力与变形变化情况。计算表明软土的总变形量中蠕变变形量大于53.6%。由此可见减小基坑软土层的蠕变对基坑的安全有着显著的意义。对比结果再次证明了软土的蠕变将对基坑变形产生重要影响。因此，研究软土的蠕变特性，在基坑支护设计中考虑岩土的蠕变特性具有重要的理论价值和实践意义。
[Abstract]:With the deepening of China's reform and opening up, the rapid development of China's economic construction, urban construction in the high-rise, high-rise buildings are increasing, which makes the rock and soil deep foundation pit support has become a hot. The supporting structure of foundation pit, excavation scheme and creep characteristics of soil will affect the deformation control of foundation pit, which will further affect the safety of foundation pit. In this paper, the calculation process of elastic resistance method commonly used in foundation pit design is analyzed. This method is based on the elastic theory. In the calculation of earth pressure, the determination of the key parameter m depends on engineering and personal experience, and the parameter value can not consider the creep characteristics of soft soil of foundation pit, and there may be great errors. Therefore, the finite element method should be used to verify the design scheme for foundation pit support engineering with rheological characteristics. After studying the common constitutive and creep models in geotechnical engineering, taking a deep foundation pit project in Wuhan as an example, the finite element calculation software Abaqus is used to simulate the checking calculation of the foundation pit support scheme designed by the traditional design method. A Drucker-Prager model was introduced to simulate silty clay in the site considering the coupling of plasticity and creep of soft soil. The creep behavior of soft soil is considered in this model, and the creep law of lateral wall deformation of foundation pit is obtained by analyzing the calculated results. Based on the analysis of deformation monitoring data during excavation of foundation pit, the deformation characteristics of SMW pile in practical engineering are obtained. The results of finite element method are compared with the results of actual monitoring. The results show that the deformation data are in good agreement with each other, which verifies the hypothesis and rationality of the finite element calculation model of foundation pit. Finally, according to the characteristics of deformation and creep of foundation pit, the improved method of foundation pit support is improved. The results of finite element model calculation of improved support scheme are compared with those of the original scheme, and the stress and deformation changes of soil and supporting structure around the foundation pit are obtained. The results show that the creep deformation of soft soil is greater than 53.6. It can be seen that reducing the creep of soft soil is of great significance to the safety of foundation pit. The results show that the creep of soft soil will have an important effect on foundation pit deformation. Therefore, it is of great theoretical value and practical significance to study the creep characteristics of soft soil and to consider the creep characteristics of rock and soil in the design of foundation pit support.
【学位授予单位】：武汉轻工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.2

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