双真空面处理吹填土地基的计算和模拟

Calculation and Simulation of Filling Earth Foundation under Two-layer Vacuum Preloading

真空预压在软基工程中的应用越来越广泛。基于太沙基一维和轴对称固结理论,建立双面真空预压的固结解答,推导砂井地基向均质地基转化时渗透系数的等效公式,进一步建立单面负压和双面负压下土体固结度与时间的关系。利用有限元软件ABAQUS分别针对常规单面真空预压和双面真空预压的工况进行模拟,比较了地基总沉降、分层沉降在2种工况下的差异。最后对应采用双面真空预压法时使吹填土和原地基土同时达到固结稳定的工程需求,通过计算分析吹填土厚度和砂井间距的优化选择。研究结果表明,双面真空预压在吹填土和原地基土的固结效率上都有相当的优势,优势的大小与土体厚度﹑土体渗透性及砂井参数有关。

As the method of vacuum preloading has been used widely practically, it is presented in this article that the solution to soil consolidation and to the equivalent percolation coefficient transforming from sand drain soil into sand wall soil in condition of two vacuum sides, and also to the degree of consolidation between one- layer vacuum side and two-layer vacuum sides, based on Terzaghi concretion theory. The numerical analysis system Abaqus is used to simulate filling earth groundsill under two-layer vacuum sides as well as one-layer vacuum side, and to compare the whole settlement and layer settlement in two conditions. The optimal choice of the thickness of filling earth and interval space of sand drains is discussed at last in order to make the soil both filled or original consolidate simultaneously. It is proved by this article that the consolidation efficiency of using two-layer vacuum sides is more superior than that of one-layer vacuum side, the level of the superiority is determined by the thickness of filling earth, permeability of soil and sand drain parameters.