抽真空引起周围土体竖向变形的有限元分析

真空预压法加固深厚超软土地基时，一方面使地基土体产生侧向收缩变形，有利于地基的稳定；但另一方面向真空预压区的侧向变形对周围房屋、地下管线、道路等建筑物也产生不利影响，甚至会出现管道断裂、围墙倒塌、路堤被毁等严重工程事故。结合真空预压加固软基工程中出现的对周围环境影响的问题，进行了考虑土体拉裂影响的有限元分析，研究抽真空过程及加固区外不同距离、不同土体深度沉降的变化规律。研究结果表明，采用Biot固结理论、考虑土体拉裂的有限元计算结果与现场加固区外土体沉降及影响区范围的实测结果基本一致。

FEM analysis of vertical soil deformation caused by vacuum pumping

When deep and thick soft ground is improved by vacuum preloading, lateral contract deformations will be induced in the soils, and this is beneficial to ground stability. On the other hand, the lateral deformation towards the vacuum preloading area will have an adverse effect on the adjacent buildings, underground pipelines, road embankments and other structures. Serious engineering failures may take place, such as crack of the pipelines, collapse of the retaining walls, and damage of the road embankments. In order to investigate the impact of the vacuum preloading on the surrounding soils, FEM analysis has been carried out, considering the influence of soils’ tension crack. The variation behavior during the vacuum preloading process is studied on the settlement at different depths and at different distances away from the preloading area. It has been found that the calculation results from the FEM analysis based on the Biot’s theory and the consideration of tension crack are consistent with the measurement results of the settlements and the extents of the influence outside the preloading area.