Field test and numerical simulation of the thermal insulation effect of concrete pouring block surface based on DTS

Abstract

The change in environmental temperature, especially a sharp decline of air temperature, is the critical factor for cracking damage to concrete arch dam structures. In this study, the field test and numerical calculation of the insulation effect of concrete pouring block surface were performed to prevent thermal cracks in concrete arch dams. In the field test, the temperature data of concrete at different depths measured by a distributed temperature sensing (DTS) system were analysed. The results showed that the temperature of concrete at different depths from the surface was significantly positively correlated with air temperature, and the influence depth was within 50 cm from the top surface of pouring block. During numerical simulation, the differences in surface insulation measures in insulation materials, insulation thickness, insulation time, and insulation space position were simulated and compared, considering the influence of the concrete insulation layer and cooling water. The numerical solutions showed that: (1) When the insulation material changed from 2 cm polyethylene insulation layer to 5 cm polystyrene insulation layer, the surface stress of concrete decreases from 0.86Mpa to 0.59Mpa; the insulation time was advanced to before the temperature drop, the surface stress from 0.86Mpa to 0.25Mpa; and the change of insulation position, the tensile stress of the top surface of pouring block was almost unchanged. (2) In this temperature drop, the surface insulation measure was recommended: the insulation material and thickness was the 5 cm polystyrene insulation layer, the insulation time is before the temperature drop, and the insulation position is the top surface, transverse joint surface and upstream and downstream surface of the pouring block.