| The dynamic characteristics of high-speed and long-distance rock avalanche debris flow have always been a hot and difficult topic for scholars at home and abroad.In this paper,the collapse of Pusa village in Nayong is taken as the research object.Based on the full study of the basic characteristics and deformation mechanism of Nayong collapse,an indoor small-scale model test device is designed and constructed based on the real complex three-dimensional terrain.The dynamic process of Nayong collapse is numerically simulated by PFC3 D.Finally,the interaction between the collapse body and the retaining wall is studied based on the indoor test and PFC3 D It provides a theoretical basis for the prevention and control of this type of collapse debris flow.The specific research contents and results are as follows:(1)On the basis of understanding the basic characteristics of the collapse in Nayong Pusa village,according to the DEM data near Nayong Pusa village measured by UAV,the indoor small-scale model test device was designed and constructed according to the principle of geometric similarity coefficient CL = 500.The effects of debris particle size,debris volume,release times and particle gradation on the movement distance,accumulation range and accumulation height of debris were studied Ring.The results show that: the complex terrain significantly affects the accumulation characteristics of debris,especially the movement distance and accumulation width;the particle size mainly affects the accumulation range of debris;the debris volume mainly affects the accumulation height;the release times mainly affect the movement distance and accumulation height of debris;the particle size has little influence on the test results.(2)The PFC3 D numerical calculation model is established to show the movement process and clastization of rock avalanche in three-dimensional real terrain.The results show that when the friction coefficient of slope is 0.3,the indirect contact stiffness ratio of particles is 10,and the parallel bond strength of particles is 0.5MPa,the numerical simulation results are most similar to the actual collapse process.The velocity of Nayong rockfall debris flow increases rapidly to 43-47 m / s within 7S after the collapse.The debris flow moves from gentle slope to hillock in front of the slope in 7-12 s,and gradually decreases to 30 m / s under the influence of complex terrain.The debris flow moves downward from the top of hillock in front of the slope in 12-15 s,and gradually increases to 36-39 m / s under the transformation of gravitational potential energy.The debris flow is on the gentle slope in 15-36 s In this process,debris flow moved to the area of Pusa village and destroyed some houses and buildings.(3)According to the indoor model test device,a test device for the interaction between rock avalanche and retaining wall is constructed,and the impact force of debris is calculated and analyzed by theoretical calculation combined with PFC3 D numerical simulation.The results show that the greater the velocity of debris flow front moving to the retaining wall position,the greater the kinetic energy loss after colliding with the retaining wall;when the retaining wall position is fixed,different heights of retaining wall impact With the increase of the height of the retaining wall,the peak impact force and the pressure FGF of the interceptor on the retaining wall will increase;with the same height of the retaining wall,the higher the velocity of the front edge of debris flow moving to the retaining wall,the stronger the impact force on the retaining wall. |
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