Temperature effects and damage characteristics of concrete pour in large‐volume floor of subway‐station baseboard

Abstract

AbstractSubway stations are important components of subway system planning and urban rail transit where passengers can board, alight, transfer, or wait. With an increase in urban passenger flow, subway stations must meet greater transfer‐space demands commensurate with growing station structure sizes. In this study, the field‐monitoring and analysis method was adopted to investigate the Huaxing Street Station of the Chengdu Metro Line 19 project and explore the temperature‐variation rule in the process of mass‐concrete pouring in the station floor. Based on an ABAQUS large‐finite‐element calculation programme and secondary development of damage and failure research methods, a mechanical model of mass‐concrete pouring in subway‐station floor construction was established. The pouring temperature effect, damage, and failure mechanism of mass‐concrete pouring in subway stations were comprehensively studied. The main results were as follows: (1) the maximum temperature difference between the upper and middle layers of the floor was dominant and reached a peak within 1–3 d after the completion of pouring, and the temperature difference gradually decreased with a decrease in the hydration‐heat reaction. (2) At 0–10 d, the damage ratio of the floor increased by 1.8%, predominantly in the form of longitudinal damage. Within 10–30 d, the damage and failure ratio of the floor increased by 1.86%, primarily in the form of transverse damage and failure. Within 30–40 d, the temperature of the floor stabilized and gradually approached the ambient temperature. The damage and failure ratio of the floor increased by 0.32% at this time. (3) The lower the ambient temperature, the greater was the damage sustained by the floor at different ages, and the ambient temperature had a significant influence on floor damage.