| Debris flow is a common natural geological disaster in the world,which has caused huge losses to the economic development of mountainous areas and the safety of people's lives and property.The prevention and control of debris flows in mountainous areas is very urgent.In debris flow prevention and control projects,blocking dams are a direct and effective means.The multi-stage debris flow blocking dam built in the debris flow basin mainly plays the role of weakening the flow rate of the debris flow,intercepting the solid matter of the debris flow,and solid bed protection.Particulate matter is a unique substance different from solid,liquid,and gaseous substances.It exhibits many peculiar phenomena and unique laws of motion in static characteristics,vibration characteristics,and flow characteristics.It has been found that when particulate matter flows through the funnel or channel,when the size of the opening is reduced to 4 times the particle size,the particles are completely blocked and the flow stops.When the particulate matter is blocked,the collision between particles and the friction between the particles and the wall consume the kinetic energy of the particle flow system,which is an energy dissipation system.Starting from the blocking characteristics of particulate matter,studying the movement characteristics of debris flow when it is blocked,providing reference for future debris flow oblique blocking dam design,improving the comprehensive ability of debris flow prevention and control projects,and having important value and reality for ensuring the economic development of mountainous areas and the safety of people's lives significance.Based on the blocking phenomenon of particulate matter,this paper introduces the concepts of storage ratio and relative opening size through small-scale model tests,analyzes the blocking characteristics of particle flow,and measures the effect of particle flow on the diagonal baffle and transverse baffle with different opening sizes.Force and velocity fields,combined interception volume and force,obtain the best relative opening size for intercepting particle flow;through large-scale test models,analyze and simulate the siltation form and blockage characteristics of debris flow in front of the oblique baffle and the lateral baffle,and compare The force and particle velocity field on the oblique baffle and the transverse baffle.The main conclusions are as follows:(1)The particle flow has three states: fully blocked,semi-blocked and unblocked before the exit of the oblique baffle.The dominant particle blocking is the friction between the particles and the groove wall and the arching between the particles.In the semi-blocked state,the particles flow intermittently at the outlet,and the arch structure between the particles is more obvious at the outlet,and the blocking structure has an obvious retardation effect on the particle flow.(2)When the relative opening size increases,the normal force on the oblique baffle continues to decrease.When the relative opening size is within the range of 1-2,the force decreases obviously.When the relative opening size is greater than 2,The downward trend of the acting force begins to tend to be gentle,and the normal acting force on the diagonal baffle with different opening sizes is smaller than that of the lateral baffle.Comprehensive flow storage ratio and force,when the relative opening size is 2.5,the interception effect of the oblique baffle is the best,which is the best relative opening size.(3)In the process of particle flow and simulated debris flow flowing in the chute,there is a phenomenon of inverse particle order distribution of particles,that is,the particle order distribution of fine particles on the bottom and coarse particles on the top.In the process of simulating the flow of debris flow,the particle movement speed at the leading position is the largest,and there is a "leading effect".At the same time,the collision between particles in front of the oblique baffle is more intense,and the speed decreases faster. |
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