考虑拉伸与压缩不同徐变特征的混凝土连续墙早龄内应力分析

EARLY-AGE STRESS ANALYSIS OF CONCRETE DIAPHRAGM WALL THROUGH TENSILE AND COMPRESSIVE CREEP MODELING

以某大型交通枢纽地下连续墙为工程背景,首先讨论了早龄混凝土分别针对受拉和受压状态的应力松弛特性,给出了考虑不同力学状态的混凝土早龄内应力计算方法;然后设计和实施了地下连续墙体实体模型试验,通过实体模型模拟了地下连续墙初衬与内衬之间的连续构造和滑动构造,采用埋入式温度、应变传感器测量了模型墙体内部的温度历程和应变历程;结合已经校准的混凝土早龄拉伸徐变规律以及现场混凝土材料力学特性,实现了对模型墙体的内应力发展历程的仿真计算,并通过与实测数据的对比验证了仿真结构的正确性;最后,对真实结构中的足尺连续墙体进行了数值分析,根据计算结果讨论了初衬与内衬之间的合理构造方式以及早龄开裂风险。

For the early-age stress analysis of a massive concrete diaphragm wall in the underground part of a transport complex hub, this paper presents firstly the stress analysis algorithm considering both tensile and compressive creep behaviors of early-age concrete. Then the in-situ large-scale model test of a diaphragm wall is designed and performed to simulate the sliding and continuous connections between the inner and external layers. Thermal and strain sensors are installed to record the temperature and strain histories inside the model wall. With available mechanical properties and calibrated tensile creep law for the structural concrete, the stress analysis is effectuated on the model wall and the results are validated by the in-situ measurements. Furthermore, the stress analysis is performed on the full scale diaphragm wall. Based on the numerical results, the rational connection option between layers and cracking risk of the diaphragm wall are discussed.