基于变形机理真空预压变形实用计算方法

发布时间：2018-07-16 12:35

【摘要】：近年来，随着我国基础设施建设的高速发展，真空预压，这种地基处理方式在软土地区有了很广泛的应用。在我国沿海地区存在大量的软土。实践表明，真空预压这种地基处理方法在软土地基处理中有着诸多优势。真空预压地基处理方法对沉降限制严格的工程，诸如港口、机场跑道、高速铁路路基的施工非常适用。随着真空预压地基处理方法的广泛运用，对于真空预压作用机理的研究也更加的深入。但是，真空预压的设计计算却没有一个统一的理论。目前，对于真空预压地基变形的计算，大多数是仿照堆载预压的方式。这种方法即是将真空预压的摸下真空度等效为等效均布荷载作用的地基表面上，算出土层中的应力分布，再利用分层总和法进行计算。实践表明，这种计算方法存在很大的误差，需要引入一个经验系数ψ s来减少这种误差。而经验系数的取值又有一定的随机性并且得不到很好的总结。因此，当前真空预压地基的沉降计算有很大的缺陷，重新寻找一种能够反映真空预压作用机理的计算方法是十分必要的。本文在前人工作的基础上，进行了如下方面的分析研究：（1）分析真空预压的加固机理，并和堆载预压的加固机理进行比较，通过对比来总结现有的真空预压设计计算理论所存在的问题；（2）根据真空预压地基的变形机理，，提出真空预压地基变形计算的弹性理论方法。该方法可计算出土层中任意点的应力应变，并推导出基于弹性理论的真空预压变形计算的分层总合法；（3）在弹性理论的基础上，利用MATLAB编写相应的计算程序，结合有关工程实例证明本文相关理论的可靠性，在此基础上提出角点法。利用MATLAB编写相关程序验证角点法是否可靠；（4）在角点法的基础上，推导关于土体应力的无量纲方程，并推导相应的应力系数、编制应力表格实现本文分层总和弹性理论计算的实用化和简便化，服务与工程设计计算。
[Abstract]:In recent years, with the rapid development of infrastructure construction and vacuum preloading, this method of foundation treatment has been widely used in soft soil areas. There is a large amount of soft soil in the coastal areas of our country. Practice shows that the method of vacuum preloading has many advantages in soft soil foundation treatment. The treatment method of vacuum preloading foundation is very suitable for the construction of roadbed of seaport, airport runway and high speed railway. With the extensive application of vacuum preloading foundation treatment, the study of vacuum preloading mechanism is more in-depth. However, the design and calculation of vacuum preloading does not have a unified theory. At present, the calculation of foundation deformation under vacuum preloading is based on surcharge preloading. In this method, the vacuum degree of vacuum preloading is equivalent to the equivalent uniform load on the surface of the foundation, the stress distribution in the soil layer is calculated, and the method of stratified summation is used to calculate the stress distribution. Practice shows that there is a large error in this method, and it is necessary to introduce an empirical coefficient 蠄 s to reduce the error. The value of empirical coefficient is random and can not be summarized well. Therefore, at present, the settlement calculation of vacuum preloading foundation has great defects, so it is very necessary to find a new calculation method which can reflect the mechanism of vacuum preloading. Based on the previous work, the following aspects are studied in this paper: (1) the mechanism of vacuum preloading is analyzed and compared with that of surcharge preloading. The existing problems of vacuum preloading design and calculation theory are summarized by comparison. (2) according to the deformation mechanism of vacuum preloading foundation, the elastic theory method of vacuum preloading foundation deformation calculation is put forward. This method can calculate the stress and strain at any point in the soil, and deduce the total layered method for the calculation of vacuum preloading deformation based on elastic theory. (3) on the basis of elastic theory, the corresponding calculation program is compiled by MATLAB. Combined with some engineering examples to prove the reliability of the related theory in this paper, a corner point method is put forward on the basis of it. Using MATLAB program to verify whether the corner method is reliable. (4) based on the corner point method, the dimensionless equation of soil stress is derived, and the corresponding stress coefficient is derived. A stress table is compiled to realize the practical and simple calculation of the layered summation elasticity theory, and to serve and calculate the engineering design.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU472

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