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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。
Taking the underground diaphragm wall of a large transportation hub as the engineering background, the stress relaxation characteristics of early age concrete under tension and compression are discussed. The calculation method of internal stress of early age concrete considering different mechanical conditions is given. Then, The solid model test of underground continuous wall was carried out. The continuous structure and sliding structure between the initial lining and the lining of underground continuous wall were simulated by solid model. The temperature history of model wall was measured by embedded temperature and strain sensor. Strain history of the concrete wall and the history of tensile stress and strain of the concrete body have been calibrated and the mechanical properties of the concrete in the site have been combined to simulate the development process of the internal stress of the model wall and verify the correctness of the simulation structure by comparison with the measured data Finally, the numerical analysis of the full-scale continuous wall in the real structure is carried out. According to the calculation results, the reasonable construction method of the initial lining and the lining and the risk of early age cracking are discussed.