| Landslide debris flow is a common form of movement of high-level landslides.It is characterized by large-scale,long-range,and high-speed.It often causes devastating disasters and seriously threatens the lives and property of people in our mountainous areas.Carrying out research on the impact effect and accumulation characteristics of landslide debris flow on protective structures not only helps to improve the level of research on the mechanism of debris flow impact disasters,but also improves and innovates the basic theory.The basis is of great scientific significance and practical significance for protecting the safety of mountain infrastructure and people's lives and property.In this paper,the structure is taken as the research factor,considering the parameters such as the height of the stop structure and the combination of the slope.It uses model tests and numerical simulation methods,with impact force as the core,and combines particle sorting,energy evolution characteristics,and stack distribution to analyze different structures blocking effect of debris type and form on debris flow.1)When the angle of the slope foot ??45°,the time history curve of the impact force experienced a linear increase and a linear decrease,and the blocking effect was significant.When the angle of the slope foot is 55°,the time-history curve of the debris flow impact force appears in three stages: linear increase,holding stage,and linear decrease.The higher the baffle height,the shorter the duration of the holding phase,and the longer the duration of the linear decrease of impact force.In the particle grading used in this paper,the impact of small particles(2.5-10mm)on the baffle is significant;while large particles(25-60mm)have a sudden change in the impact on the baffle,the impact is not significant.The flow of debris flow gradually decreases with the height of the baffle.2)Due to the deflection structure,the movement direction of the debris flow particles is deflected,and the maximum speed of the sliding body changes from the foot of the slope to the trailing edge of the particles on the chute.With the increase of the width of the deflection structure,the normal force increases significantly;the area of the accumulation zone and the maximum horizontal movement distance continue to decrease,and the area of the safety zone gradually increases.The dimensionless number(Nk)is defined to define the particle sorting effect.When the block width is the same,the particle sorting effect decreases with the increase of the particle size;small particles(2.5-10mm),medium particles(10-25mm)The Nk value of large particles(25-60mm)gradually increases with the increase of the width of the deflection structure.When the deflection structure is set at the foot of the slope,the volume percentage of debris flow particles gradually decreases with the increase of the moving distance;without the deflection structure,the volume distribution reaches a peak near the middle position,and decreases to both sides,which is equal to the Extreme function Corresponding.3)The numerical simulation analysis of three different structural forms(concave arc,straight line,convex arc)to guide the debris flow shows that the concave arc structure can effectively transform the impact force of the debris flow particles,It has the largest guiding effect on particles.The influence of the particle kinetic energy change of the debris flow is mainly due to the collision and friction between the particles and the chute;the effect of the lead structure has a significant effect on the volume distribution of particle accumulation near the foot of the slope,and the concave arc structure is the best. |
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