Experimental study on seepage monitoring in asphalt concrete core rockfill dams using distributed optical fibre sensing

To apply distributed optical fibre temperature sensing technology to seepage monitoring in asphalt concrete core dams, this study develops a scaled physical model based on the prototype of the Yazhai Reservoir asphalt concrete core rockfill dam in Guizhou, which is currently under construction. Three typical seepage defects were introduced in the core, including waterstop-failure seepage at construction joints, through-crack seepage in the core wall, and localised concentrated seepage. Model tests were carried out using the active heating optical frequency domain reflectometry (AH-OFDR) method. By applying different water levels and heating power levels, the temperature response characteristics associated with each type of seepage defect were analysed to assess the applicability of distributed temperature sensing (DTS) technology for seepage monitoring in asphalt concrete core dams. The results provide a basis for improving seepage monitoring schemes and for identifying seepage during dam construction and operation. The experimental results show that distributed temperature sensing withactive heating can identify seepage locations effectively, and different seepage forms exhibit distinct temperature response patterns. Heating power and water level influence the monitoring performance, and appropriate selection of heating parameters can improve the accuracy and reliability of seepage identification.