Theoretical model and its experimental validation of soil seepage velocity monitoring based on artificial thermal field

In earth-rock dam engineering， the feasibility of using temperature for seepage safety monitoring has been verified. However， quantitatively assessing the flow velocity in soil based on the temperature field remains an unresolved issue. In this regard， this paper constructs an artificial thermal field seepage analysis model that considers the thermal-seepage flow coupling effect， using the finite element method to study the cooling patterns of monitoring wells under different seepage velocities， and validates the findings through laboratory experiments. The results indicate that： （1） When the seepage velocity is lower than 1×10-4 cm/s， the heat transfer process is primarily governed by heat conduction， with the influence of heat convection being negligible； further reducing the seepage velocity has little effect on the heat transfer process. （2） The selection of the initial temperature does not affect the cooling pattern， which is solely related to the seepage velocity in the surrounding soil. Therefore， when applying the artificial temperature field technique for flow velocity analysis in practical engineering， it is unnecessary to strictly control the initial temperature. （3） There is a monotonic relationship between the cooling constant λ and the seepage velocity v， and the proposed exponential decay function fits well with the water temperature decline process inside the monitoring well， enabling accurate prediction of the seepage state in soil based on the cooling curve of the artificial temperature field. In summary， this study validates the feasibility of determining flow velocity in soil using an artificial thermal field and provides theoretical support for flow velocity measurement.