明挖装配式地下车站侧墙叠合层现浇混凝土开裂风险研究

Study on the Cracking Risk of the Cast-in-situ Concrete on the Side Wall Laminated Layer of the Open-cut and Prefabricated Underground Station

采用装配式结构与现浇混凝土施工相结合的方式,不但能缩短工期、节省造价,而且可以提高工程质量。依托某轨道交通地下车站工程,基于室内试验和多场耦合理论模型,对明挖装配整体式地下车站侧墙叠合层现浇混凝土开裂风险进行了研究。结果表明:尽管现浇混凝土厚度较薄,但仍因强度高而产生明显的温升温降,且早期收缩大,当收缩变形受到C50高强预制板和底板约束作用时,导致基准混凝土开裂风险较高;采用无收缩高性能混凝土可有效降低现浇叠合层混凝土的开裂风险,当一次性浇筑长度不大于21 m时,可避免混凝土裂缝的产生。

The method of combining the prefabricated structure and the cast-in-situ concrete construction can shorten the construction period,save the cost,and improve the quality of the project.Based on certain rail transit underground station project and on indoor test and multi-field coupling theory model,study on the cracking risk of the cast-in-situ concrete on the side wall of the laminated layer of the open-cut and assembled integral underground station.The research shows that the cast-in-situ concrete is relatively thin,it still has obvious temperature rise and drop due to high strength,coupled with large early shrinkage deformation and large constraint of C50 high-strength precast slab and bottom plate,which leads to relatively higher cracking risk of reference concrete.When high performance concrete with non-shrinkage is used,the cracking risk of the cast-in-situ concrete can be effectively reduced.When the one-time pouring length is not more than 21 m,concrete cracks can be avoided.