现代气压沉箱施工过程的三维有限元分析

3D FEM Analysis on Modern Pneumatic Caisson Construction

摘要:

从开挖卸荷、刃脚挤土、沉箱土体侧摩擦作用三方面对气压沉箱施工引起的土体扰动进行分析，并结合工程实例，对气压沉箱施工全过程进行三维有限元数值模拟.通过与现场监测数据的比较，验证了三维计算模型及数值模拟方法的合理性和有效性.结果表明：沉箱侧壁边缘处地表沉降最大；随着沉箱下沉，地表沉降逐渐增大，沉降影响范围随之扩大；沉箱周边土体的水平位移较小，浅层土体偏向沉箱移动，深层土体偏离沉箱移动；考虑刃脚挤压扰动可以有效减小沉箱边缘处最大地表沉降.

Abstract:

Combined with the construction example, the 3D FEM simulation with a consideration of the soil disturbance during construction was proposed to predict the soil movements induced by the new pneumatic caisson method construction. The calculated soil movements were examined and verified by the field measurements. The results indicate that the maximum surface settlement exists in the caisson wall edges. During the caisson sinking progresses, the settlement increases and the influence zone on the ground surface is widened gradually. The subsurface horizontal displacements are small and vary along depths. The shallow soils tend to move towards the caisson and the maximum displacement occur to the surface, whereas the deep soils tend to move away from the caisson. Finally, the effects of several parameters which might affect the ground deformation were investigated. It can be concluded that the surface settlements close to the caisson walls are reduced significantly because of the compacted zone existence.