现浇隧道侧墙混凝土早期收缩开裂行为

Shrinkage cracking behavior of cast in situ tunnel sidewall concrete at early age

基于考虑材料、结构、环境、施工等多因素交互作用机制的收缩模型,评估了绝热温升、自收缩及功能材料对现浇隧道侧墙混凝土早期收缩开裂行为的影响。结果表明,通过配合比优化来制备低温升、低收缩混凝土难以抑制侧墙混凝土收缩开裂。采用功能材料后,侧墙混凝土开裂风险随功能材料在温升阶段的膨胀效能的增加、膨胀持续时间的延长以及在温降阶段的补偿变形的增加而降低。通过对混凝土温度和全过程收缩变形的共同控制,可抑制侧墙混凝土早期收缩开裂。3种典型工况的侧墙混凝土温度与变形监测结果及实体长期跟踪结果与评估结果一致。

Based on a multi-field coupling shrinkage model simultaneously considering the factors of materials,structure,environment and construction,effect of adiabatic temperature rise,autogenous shrinkage and functional material on the early age shrinkage cracking behavior of cast in situ tunnel sidewall concrete were studied.Results indicated that sidewall concrete is still susceptible to suffer penetrating shrinkage crack at early age by optimizing mix proportion to prepare low temperature rise and low shrinkage concrete.After functional material was adopted,the cracking risk of sidewall concrete was decreased with the increasing of expansion ability and duration of functional material in temperature rise stage,the continuous shrinkage compensation ability in the temperature drop stage of functional material.The early age shrinkage crack of sidewall concrete can be inhibited by controlling temperature and whole process shrinkage deformation at same time,this result was consistent with the three typical engineering practices by monitoring temperature and deformation of entity structure and continuous field observation.