Abstract: Constant seepage conditions are one of the main hydrodynamic conditions for triggering the debris flow. However, few scholars have studied the triggering discriminant model and the variation of hydraulic parameters in the slope. In this paper, a simple geological structure consisting of the debris is selected for theoretical analysis, and the triggering discriminant model of debris flow is established. The variation of hydraulic parameters in the slope is studied by means of the model test. The discriminant model is verified and compared with other models. The results show that both the seepage force and the seepage scouring force play an important role in controlling the movement of debris during the constant seepage process. The seepage velocity increases with the increase of bed slope and inlet water flow rate, but the variation degree is smaller for the latter case. The total water head loss parallel to the water flow direction decreases at first and then increases with the increase of the bed slope, and it has a positive correlation with inlet water flow rate. The stability coefficient and the bed slope show a power function relationship. The correlation coefficient differs depending on different discriminant models. Compared with other models, the discrimination model presented in this paper is strictly deduced to meet the requirements of dimensional analysis and experimental verification, and it has a much higher accuracy.

Key words: 国家重点研发计划项目（No.2017YFC1502502, No.2017YFC1502506）；国家自然科学基金项目（No.51679229, No.41672318）；云南省应用基础研究计划项目（No.2016FB074）；中国科学院成都山地所135项目（2017年）；中国科学院青年创新促进会（No.2018405）。