Abstract: In the curing process of mass concrete structures, due to the hydration heat accumulation during the condensation stage of the concrete, the internal temperature of the concrete rises sharply, and a great temperature difference appear compared with the outside temperature of the concrete structure. When the differential temperature exceeds a certain level, the tensile stress of the structural surface exceeds its limiting range and then it could result in the temperature cracks inside the newly poured concrete. The Brillouin Optical Time Domain Analysis (BOTDA) temperature measurement technique has the advantage of all distributed mode, high accuracy and easy measuring. The BOTDA distributed optical fiber temperature measurement technology was applied to the longterm measurement of hydration thermal temperature of a large diameter concrete caisson in a landslide mitigation project in Badong third Middle School. Combined with the traditional temperature measurement methods, a longterm temperature monitoring data were obtained. The analytical results show that the BOTDA distributed optical fiber temperature measurement technique applied to the temperature monitoring of the solidification stage of the pile concrete, has the significant advantages over the traditional temperature monitoring method. The new method is able to response to the temperature change along the entire caisson length in a timely and accurately manner, and provide a realtime data.

Key words: hydration heat, Brillouin Optical Time Domain Analysis Sensing System (BOTDA), Caisson, Monitoring