基于三维数值模拟的深基坑隔断墙优化设计

作为一种保护邻近建筑物的措施，隔断墙已经开始在深基坑工程中应用，但目前对其有关参数的设计还缺乏理论指导。以某软土地区深大基坑实例为背景，利用有限元分析软件ABAQUS，建立三维有限元分析模型，土体采用修正剑桥模型，模拟开挖实际工况，深入分析了隔断墙各设计参数对保护基坑邻近建筑物效果的影响，邻近建筑物沉降计算值和实测值验证了隔断墙参数优化分析结果的合理性。研究结果表明：地表位移、建筑物的横向角变量和围护墙最大位移随着隔断墙深度的增加而逐渐减小，但建筑物横向角变量的减小幅度趋缓，隔断墙存在一合理深度；随着隔断墙的位置逐渐从基坑侧壁向邻近建筑物移动，隔断墙外侧地表横向和纵向沉降以及纵向不均匀沉降均减小，建筑物的横向角变量也明显减小。理论上，隔断墙越靠近邻近建筑物，保护建筑物的效果越好；隔断墙的平面设置范围对于邻近建筑的保护效果也有着明显的影响，一般情况下可以取邻近建筑物的范围作为隔墙的合理设置范围；隔断墙刚度对地表位移和建筑物角变量影响不大，实际工程中宜取中等刚度的隔断墙。

Optimization design of partition wall in deep excavations based on 3-D numerical simulation

As a technique for protecting adjacent buildings,partition wall has got an application to deep pit engineering.However the design of its parameters still lacks theoretical guidance.Based on a large-scale deep pit case,a 3-D finite element model is presented using the software ABAQUS.The behavior of soil is assumed to conform to modified Cam-clay model;and the actual construction sequence is simulated.Parameters relevant to the partition wall are analyzed in detail.The calculated and measured settlements of the adjacent building demonstrate the rationality of the optimization analysis of these parameters.It is shown that the ground surface displacements,the transverse angular distortions of the building and the maximum horizontal displacements of the retaining wall decrease with the increase of the partition wall depth.Nevertheless,the rate of the decrease of transverse angular distortions tends to be small if the partition wall depth is greater than a certain value.Thus there exists a reasonable depth for the partition wall.As the partition wall moves toward the adjacent building,the transverse and lengthways ground settlements,the differential settlements as well as the transverse angular distortions of the building decrease.Theoretically,the closer the partition wall is to the adjacent building,the better its effects are.The installation plane range of the partition wall also has significant influence on the adjacent buildings.Usually the range of the protected building can be the appropriate range of the partition wall.It is also shown that the stiffness of the partition wall does not affect the surface settlements and the angular distortions of adjacent building significantly,a medium-stiffness partition wall is sufficient to meet the engineering demands.