| High-speed and long-term landslides-The debris flow which often causes a huge catastrophic accident in emergency situations resulting in serious loss of life and property due to its characteristics of extremely high movement speed and ultra-longdistance displacement.In particular,does it change which generated by landslides undergoing high-speed movements in the movement of rivers with saturated water deposits with extremely high water content? How do the distance change? On the basis of data review and site investigation of typical landslides,this paper uses the physical model test of the indoor water tank to thoroughly investigate the migration mechanism of saturated sand accumulations after impacted by high-speed moving debris flow.Through a large number of indoor tank model tests,considering the debris flow of the same type and quality,the same quality of different types of debris flow,and changing the slope of the trench where the deposition layer is located,the study explores the movement of the accumulation body,the liquefaction phenomenon,and the internal Mechanism changes.The main research results are as follows:(1)The saturated accumulation layer will move forward along with the debris flow under the impact of the debris flow subjected to high-speed movement.The movement form will waft forward in a “wavy” shape,and the whole sliding will be obviously fluidized.After the sliding stops,the trailing edge of the accumulation layer is flushed and the whole slides forward.The debris flow is concentrated on the trailing edge of the water tank,and the stone from the back edge of the water tank to the front edge is gradually reduced.(2)The external shape and quality of the debris flow have a great influence on the migration of the accumulation layer.The greater the quality of the same type of debris flow,the more pronounced the impact on the accumulation layer,the more sliding of the accumulation layer,the faster the speed,the more slipping form,and the smoother the shape of the debris flow under the same mass conditions,the accumulation layer after the impact,the movement distance is farther and the migration speed is faster.(3)The pore water pressure has a significant change in the accumulation layer under the impact of debris flow.At the bottom of the accumulation layer,the pore pressure is affected by the pore pressure.Because the pore pressure is fixed at the same position,the pore pressure value surges to form the excess pore water pressure,the effective stress is reduced or disappeared,and the soil particles are in a suspended state,showing a clear liquefaction phenomenon.After the pore pressure in the upper part of the sedimentary layer was impacted,the pore pressure increased sharply and reduced and appeared alternately.Finally,the stability was negative,indicating that the upper part of the accumulation layer had obvious dilatancy and shearing phenomenon.(4)The sliding of the accumulating layer is accompanied by the dissipation of energy.The more thoroughly the sliding of the accumulating layer,the more complete the dissipation of energy.In the case where there is no overall sliding or sliding of the accumulation layer,a large amount of water seeps out in the debris flow accumulation area at the trailing edge,indicating that the accumulation layer is not sufficiently sliding,and if the energy is not fully dissipated,the particles will have a significant collision,resulting in Free water precipitates between particles.(5)In addition to the debris flow quality and external shape,the slope of the channel is also an important factor influencing the migration of the accumulation layer.The sliding of the accumulation layer must be established on the basis of a certain slope.The greater the slope,the more obvious the movement of the accumulation layer,the greater the distance,the more obvious change of the internal pore pressure,and the more complete energy dissipation. |
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