Model Test-based Study Of The Impact Process And Mechanics Of Ice-rock Debris Flow

Ice-rock debris flow is a special debris flow that occurs in high cold,steep and high altitude mountainous areas,formed by ice avalanches or rock avalanches wrapped with ice and rock debris in high speed movements.Due to its strong mobility and destructive power,it poses a great threat to major projects and the safety of people’s lives and property in the region.Therefore,based on indoor chute tests,this paper mainly investigates the influence of the material composition of the ice-rock debris flow(influencing factors such as ice content and particle size)on its kinematic indicators such as flow velocity and flow depth and its impact loads when impacting a rigid retaining wall,and verifies the applicability of the ice-rock debris flow with typical impact force models.The main findings of the thesis are as follows.(1)Ice content mainly affects apparent density and frictional properties.When the volume of the ice debris flow is constant,the apparent density of the ice debris flow decreases linearly with increasing ice content,and the angle of repose,the angle of friction with the bottom of the chute and the angle of friction with the retaining wall decrease with increasing ice content.For the same ice content,the friction angle is approximately the same for ice debris flows with different ice rock grain sizes(1.0 to 1.5cm).(2)Ice content and particle size are the main factors affecting flowability.The higher the ice content,the lower the friction,resulting in a positive correlation between the flow velocity and depth of ice debris flow and the ice content,When the ice content is below 50%,the increase in flow velocity with ice content is relatively large.the larger the particle size of the ice rock particles in the ice rock debris flow,the smaller the particle contact surface per unit volume and the smaller the internal friction,resulting in relatively large movement indicators such as flow velocity and flow depth.(3)The particle size of the ice rock is within a certain range(1.0 to 1.5 cm)and the particle sorting of the ice rock debris stream is mainly controlled by density differences.When the ice particles are of the same size,the ice debris flow will show a "top ice and bottom rock" structure during the process of particle sorting,while when the size of the ice particles decreases,the final accumulation will still show a "top ice and bottom rock" structure.It shows that the particle sorting that occurs during the movement of the ice-clastic stream is strongly influenced by the density of the ice-clastic particles.(4)Ice content and density together control the variation of impact force.As the ice content increases,the density of the ice debris flow decreases and the maximum normal impact force increases and then decreases with increasing ice content,reaching a maximum value at 40% ice content.The maximum normal impact force and tangential impact force of the ice debris flow are positively related to the particle size of the ice particles under the same ice content.(5)The higher the ice content,the lower the friction and the higher the kinetic energy per unit mass,resulting in a gradual upward shift in the height of the maximum normal impact force with increasing ice content,while the same ice content and the larger the particle size of the ice particles or rock particles,the lower the friction and the relatively higher the height of the maximum normal impact force.(6)Based on the test data,the calculation accuracy of three typical debris flow load models was compared,and it was found that the calculation accuracy of Jiang load model was relatively high,and the calculation accuracy of Ashwood load model was also relatively high when the ice content was below 60%.the impact force values calculated by the above models did not exceed 20% error from the measured values.