THE STUDY OF THE DEBRIS-FLOWS DYNAMICS ON AN EXPERIMENTAL STAND

Abstract

Designed and manufactured a test stand for the dynamic characteristics of debris-flows and for physical modelling of debris-flows. The stand is a rectangular cross-section tray with a length of 3.0 m, a width of 0.25 m, a depth of 0.25 m. The slopes of the tray vary from 10o to 45o. Rods are installed in the tray to accommodate load cells for measuring pressure, speed and temperature. The process of moving the debris-flow through the transparent wall of the debris-flow tray is filmed by a high-speed video camera. During the experiment, the velocity and high- velocity pressure of water flow and artificial debris-flow were measured. The tray was installed with a slope of 12o. Water flow was started up on the tray (to measure the flow rate and the value of the velocity head, which were then used as reference values). Then the tray was put into the flow of the prepared debris-flow mixture. The debris-flow mixture was prepared from a dredged-crushed proluvial-deluvial deposits of Holocene age with a loamy aggregate with a density of 2210 kg/m3. The density of the prepared debris-flow mixture was 1756 kg/m3. Dynamic viscosity of the debris-flow mass measured by the Stokes method was 0.0498 Poise, kinematic viscosity of the debris-flow mass was 0.0928 Stokes. Data on the debris-flow velocity measured directly during its movement of the debris-flow is not enough. Therefore, methods for calculating the speed of a debris-flow slide in its are important. One of these methods is the method of calculating the debris-flow velocity by the magnitude of the speed head (on the traces of the debris-flow on the trunks of trees). That method is based on the formula of E. Torricelli. The results of the experiment showed that the measured debris-flow velocity, calculated from the magnitude of the velocity head, was lower than the measured velocity before the obstacle and higher than the measured velocity after the obstacle. The measured velocity of the debris-flow passage of the entire tray was close to the calculated one.