Comparison of the Seepage Monitoring Results Between Saturated and Unsaturated State Using Point Heat Source Method

Unsaturated seepage exists in most geotechnical engineering. However, the research results of unsaturated seepage monitoring are relatively few. In order to study the difference of seepage monitoring results between saturated and unsaturated state, based on the point heat source method of seepage monitoring, the calibration tests of seepage velocity for two kinds of gravel soils with different gradations under saturated and unsaturated state were carried out respectively. The comparison results show that the calibration results between the two states are different. Especially for the cases with low seepage velocity, the absolute value of the seepage discrimination index obtained under the unsaturated state is greater than that under the saturated state. Therefore, the monitoring results are conservative when the seepage velocity is small and the calibration relationship under the saturated state is used to invert the seepage velocity under the unsaturated state.