【作者】 熊志福；

【导师】 闫澍旺；

【作者基本信息】 天津大学 ， 岩土工程， 2007， 硕士

【摘要】 本文研究了软土地区使用真空预压法施工对周围构筑物造成的影响。我国广大地区分布着工程性状较差的软粘土,对软粘土地基处理一般采用排水固结法。作为排水固结法的一种,真空预压加固软土地基近年得到了广泛的应用,取得了很好的工程和经济效益。目前,国内外对真空预压的作用机理及沉降的设计计算方法已进行了较多的研究,但对真空预压法对周围构筑物所造成的影响及影响因素等尚缺乏系统的研究,因此研究真空预压法对周围构筑物所造成的影响具有重要的现实意义。本文主要分析了真空预压的加固机理以及真空预压对周围构筑物所产生的竖向位移和侧向位移(主要分析了侧向位移)、产生位移的影响因素和真空预压加固地基时的侧向影响范围。首先对要研究的土体的三维固结问题转化为平面固结问题,并用有限单元法采用四结点等参元进行分析,然后对以上问题用FORTRAN语言编制了适合求解负压作用下地基固结问题的有限单元法程序,并用该程序对实际工程的加固效果进行了计算,计算结果表明程序所计算的数值与实际工程的观测值吻合的比较好,从而验证了用该程序计算真空预压对周围构筑物所造成影响的可行性和合理性,同时,可进一步直接将此程序作为工具对同类问题进行数值计算及研究。最后用上述程序对与真空预压对周围构筑物造成的竖直和水平向位移有关的参数进行独立计算分析,包括排水板打设深度和间距、加固区面积、渗透系数、膜下真空度、土体固结系数。分析结果表明真空预压对周围构筑物造成的竖直和水平向位移跟排水板打设深度和间距、渗透系数、膜下真空度、土体固结系数有较大的关系而与加固区面积基本没关系。而在软土地区的周边构筑物的影响范围与加固区宽度有关。更多还原

【Abstract】 The deformation of the structure induced by vacuum preloading in soft soil area is studied in this paper.Soft clay is distributed in the vast area of China with poor engineering properties. And the method of consolidation by drainage is usually used to treat the soft clay ground. In recent years, vacuum preloading is extensively used to treat the soft clay ground as one kind of the method of consolidation by drainage, and it has got lots of project benefit and yield good economic returns. Although there have been many studies on mechanism of vacuum preloading and the method to calculate its settlement, it is lack of system study on the deformation of the foundation induced by vacuum preloading and the influence factors. As a result, it will be helpful to go deep into the two fields for the further application of this method.In this paper, the mechanism of vacuum preloading and the vertical and lateral deformation (mainly discuss the lateral deformation) of the structures induced by vacuum preloading is analyzed. Meanwhile, the influence factors of deformation and the lateral range of influence is also discussed in this paper.First, three-demensional consolidation of the element is simplified to two-demensional consolidation. And finite element method (FEM) is used to analyze it with four-node isoparametric element. Then FEM program is compiled and improved to calculate the soil’s consolidation and deformation under negative pressure by using FORTRAN. And in comparing with the measured value, this program is proved to be reasonable and feasible to calculate the deformation.Last, the pertinency factors of deformation by vacuum preloading are analyzed individually by using the program, including the plugging depth and saparation of the draining board, coefficient of permeability, hypolemmal vacuum degree and consolidation coefficient of soil. And the result indicates that the deformation by vacuum preloading relates to the plugged depth and saparation of the draining board, coefficient of permeability, hypolemmal vacuum degree and consolidation coefficient of soil. The lateral range of influence by vacuum preloading relates to the width of reinforcement.更多还原