装配式沉井沉入过程内力与变形研究

Study on Internal Force and Deformation of Prefabricated Caisson Sinking Process

本文基于厦门市海沧区行政服务中心沉井式智能停车库的工程,结合工程监测结果对沉井沉入探讨下沉过程中的有限元分析方法,分析结果表明:沉井施工下沉过程中的井壁侧移较小,土压力接近静止土压力,地面沉降影响范围约为沉井直径的0.5倍.结合城市老旧小区的地下停车场建设,提出利用焊接连接方法加快施工进度,采用等效刚度原理探讨焊接连接的有限元计算参数,并考虑周围建筑物的影响,通过有限元分析得出:当沉井位于周围存在建筑物的老旧小区时,在有建筑物一侧沉降大幅增加,影响范围到建筑物外边缘;无建筑物一侧地表变形影响范围达到一倍的沉井直径,其中2 m范围内表现为沉降,2 m以外地表土体有隆起;有建筑物一侧产生向沉井内部的侧移,有主动土压力的趋势;无建筑物一侧产生向沉井外部的侧移,土体有被动土压力的趋势;竖向弯矩在有建筑物一侧沉井结构主要为内部受拉,而在无建筑物一侧为外部受拉,竖向弯矩峰值大致出现在深度的2/3位置处,在靠近沉井上部,从无建筑物侧到有建筑物一侧环向轴力逐渐减小,在沉井下部位置从无建筑物一侧到有建筑物一侧环向轴力逐渐增大,在深度的0.6倍处环向轴力分布接近均匀.

Based on the project of the Administrative Service Center of Haicang District of Xiamen City,this paper discusses the finite element analysis method of the sinking process of the caisson by combining the monitoring results of the project.The analysis results show that the lateral movement of the shaft wall in the sinking process of the caisson construction is small,the earth pressure is close to the static earth pressure,and the influence range of the land subsidence is about 0.5times the diameter of the caisson.Combined with the construction of an underground parking lot in the old urban district,the method of welding connection is proposed to accelerate the construction progress,and the finite element calculation parameters of welding connection are discussed by using the principle of equivalent stiffness,and the influence of surrounding buildings is considered.Through finite element analysis,it is concluded that when the caisson is located in the old residential district with surrounding buildings,the settlement on the side with buildings increases significantly.To the outer edge of the building;The influence range of surface deformation on one side of the building is twice the diameter of the caisson,in which the subsidence is manifested within 2 m,and the surface soil is uplifted beyond 2 m.One side of the building has a lateral movement to the inside of the caisson,and there is a tendency for active earth pressure.There is no lateral movement of the building side to the outside of the caisson,and the soil tends to have passive earth pressure.The vertical bending moment of a caisson structure with the building side is mainly internal tension,while the vertical bending moment of a caisson structure without the building side is external tension.The peak value of the vertical bending moment appears roughly at 2/3of the depth.Near the upper part of the caisson,the circumferential axial force gradually decreases from the construction-free side to the construction-free side,while the circumferential axial force gradually increases from the construction-free side to the construction-free side at the lower part of the caisson.The distribution of the circumferential axial force is nearly uniform when the depth is 0.6times.