混凝土内支撑结构温度效应三维数值分析

3D Numerical Analysis of Thermal Effect on Concrete Internal Bracing System

随着极端天气气候的频现,温度变化对基坑支撑结构的影响越来越不容忽视。为考虑基坑支护体系的空间效应,本文在空间杆单元协调模型基础上,采用三维有限元数值模拟的方法,研究了水土压力荷载(含支撑自重)和变温作用下内支撑结构的内力与变形。数值分析结果表明,支撑主要受轴力、弯矩和剪力共同作用,其中轴向压力最大,局部杆件根部有较大弯矩;升温增大支撑结构的内力,对轴向压力影响较大;降温增大支护结构的变形,对坑顶水平位移影响较大;支撑结构内力随温度呈线性变化,在升温和降温阶段,内力变化率不同。

With the frequent appearance of extreme climates,the influence of temperature variation on bracing system becomes more and more important. To consider the space effect of retaining system,3D finite element simulations of internal forces and deformation for the bracing system under water ＆ earth pressure（ together with selfweight） or / and temperature variation were conducted,based on coordinate spatial line element model. Several results are obtained from the numerical analysis： there are axial forces,which are the most,bending moments and shears acting on the bracing system,and the roots of some bracing members which are subjected to obvious bending moment. A temperature rise may augment the internal forces of the bracing system,especially for the axial forces;however a temperature drop may enlarge the deformation which has significant influence on horizontal displacements at the top of the foundation pit. The internal forces of the bracing system linearly increase with temperature variation,but the development rate is evidently different in temperature rise and in temperature drop.