Detecting Groundwater Flow Induced by Underground Research Laboratory Excavation through Active-DTS Measurements

The characteristics of groundwater flow within fractured rock formations and the distribution of their hydraulic conductivity form the foundational basis for subsurface engineering endeavors, including the disposal of high-level radioactive waste. Traditional methodologies for measuring groundwater flux are constrained due to their inability to gather distributed data. The novel approach, employing active distributed temperature sensing (A-DTS), presents a promising methodology for flux mapping. This study conducted flow rate tests using A-DTS within boreholes located at an Underground Research Laboratory for the Geological Disposal of High level waste in China. Utilizing the flow rate data, this investigation delineates the impact of ramp and shaft excavations on groundwater dynamics. Furthermore, the integration of flow rate data with hydraulic head measurements is essential for characterizing the flow regime and delineating the permeability structure within the granite fractures.