为探究大型基坑开挖过程中支护结构力学行为的温度效应响应规律,基于三维修正剑桥本构建立深圳滨海大道下沉隧道段基坑开挖模型,着重研究了升温与降温两种工况条件下,基坑支撑内力及围护结构变形的温度效应响应特点及其在不同温度路径中的响应差异。结果表明:相较于初始状态,环境温度升高时,基坑支撑结构受力增大,围护结构侧移量减小,坑外地表沉降量减小,围护结构轴力降低,其中支撑结构轴力对温度变化的响应尤为明显;温度降低时,基坑支护结构响应规律整体与升温工况相反;相较于升温工况,降温工况下基坑支护结构力学行为的温度效应响应更为强烈,因而对基坑结构的不利影响更为显著;与初始温度工况相比,降温20 ℃时围护结构水平位移最大增长率可超过30%,因而在场区环境温度变化较大的深大基坑工程设计施工过程中,应将支护结构温度效应考虑在内,并重点考虑降温工况。

In order to explore the temperature effect response law of the mechanical behavior of the supporting structure during the excavation of large foundation pits, the ABAQUS three-dimensional modified Cambridge model of the sinking tunnel section of Shenzhen Binhai Avenue was established. The temperature effect response characteristics of the internal force of the foundation pit support and the deformation of the retaining structure and their response differences in different temperature paths were studied under the conditions of heating and cooling. The results show that compared with the initial state, when the ambient temperature increases, the stress of the foundation pit support structure increases, the lateral displacement of the retaining structure decreases, the surface settlement outside the pit decreases, and the axial force of the retaining structure decreases. The response of the axial force of the support structure to the temperature change is particularly obvious. When the temperature decreases, the response law of the foundation pit supporting structure is opposite to that of the heating condition. Compared with the heating condition, the temperature effect response of the mechanical behavior of the foundation pit support structure under the cooling condition is stronger, so the adverse effect on the foundation pit structure is more significant. Compared with the initial temperature condition, the maximum growth rate of the horizontal displacement of the retaining structure can exceed 30% when the temperature is reduced by 20 ℃.Therefore, the temperature effect of the supporting structure should be taken into account in the design and construction process of the deep and large foundation pit engineering with large environmental temperature changes in the field area, and the cooling condition should be considered emphatically.