Temperature crack suppression measures of mass concrete for tunnel

In order to solve the problem of engineering structure safety caused by temperature crack of mass concrete in tunnel, the construction measures and monitoring data of mass concrete in Yangcheng Xihu tunnel are analyzed. First of all, six construction measures were put forward to suppress temperature cracks, including pouring in layers, controlling vibration quality, controlling the temperature of concrete entering mold, controlling mold removal time, concrete curing and controlling support removal time. Then, the High Performance Dual-Grating Temperature-Strain Sensor was used to monitor the temperature and strain of construction site structure intelligently. Based on the data analysis of the temperature and strain of the floor, side wall and top slab, it is pointed out that the temperature of the floor, side wall and top slab increases sharply first and then decreases slowly due to the release of a large amount of hydration heat during the hardening process of concrete. Due to the poor thermal conductivity of concrete, the hydration heat generated in the middle center of the floor, side wall and top slab can not be transferred to the surface of concrete in time, so the temperature is generally "high in the center and low on both sides". Due to the effect of thermal expansion and cold contraction of concrete, the strain variation trend of the floor, side wall and top slab is similar to that of temperature, showing a sharp increase at first, and then a slow decrease. Based on the mechanism of temperature crack, the variation law of temperature and strain during mass concrete pouring is analyzed, which provides reference for subsequent engineering construction.