Study On Prediction Of Dynamic Characteristics Of Debris Flow In Sigou Mining Area Based On Particle Flow

Debris flow is a special flood that breaks out in mountainous areas,which has a short duration,wide coverage and strong harmfulness.In the process of exploiting mineral resources in mountainous areas,the waste debris which is widely accumulated in the gully is easy to induce debris flow disaster and form abandoned debris flow under the action of heavy rainfall.This kind of debris flow has the characteristics of man-made,prone,frequent,hazard concentration,pollution and controllability.Through the analysis of the basic formation conditions and vulnerability evaluation of debris flow in Sigou mining area,this paper focuses on the three-dimensional modeling method of debris flow and predicting the dynamic characteristics of debris flow,as well as its impact on human and natural environment in the study area,in order to serve for disaster reduction and disaster prevention.Taking the Sigou mining area in Baoji,Shaanxi Province as the research scope,and on the basis of field geological investigation,indoor test and theoretical analysis,this paper uses the particle flow discrete element method to simulate the debris flow in Sigou mining area,focusing on predicting the dynamic characteristics of debris flow.By monitoring the trajectory,displacement,speed and impact force of particles,the start-up,migration process and disaster resistance of debris flow are analyzed.The main research contents and achievements are as follows:(1)Based on the comprehensive analysis of rainfall characteristics and geological environment conditions in Sigou mining area,it is considered that the debris flow in Sigou mining area belongs to torrential rain type,valley type and slag type.Short-term heavy rainfall and random stacking of a large number of debris are the key factors to induce debris flow.By using the combination of qualitative and quantitative evaluation methods,the vulnerability of debris flow is evaluated,and it is considered that the degree of debris flow in Sigou mining area is moderately susceptible.The failure mechanism of the accumulation body in area A(Heiyagou)is predicted by numerical simulation as follows:In the initial failure stage,the accumulation body in area A(Heiyagou)is mainly slip deformation,squeezing the front part of the accumulation body until it is unstable and sliding,and pulling the middle and upper accumulation body,which makes the whole accumulation body slide along the ground and accumulate in the No.2 slag dam,showing a tractive progressive failure.In the initial failure stage,the accumulation body in area B(Houshikenggou)slips to the channel as a whole,and silts up in the narrow channel,forming a small-scale "barrier lake",showing the overall instantaneous failure.(2)Through in-situ test and laboratory test,the natural rest angle of slag in the study area is 31°,and the slag rest angle calibrated by parameters is 30°,and the error is small,so the meso-parameters(normal stiffness and tangential stiffness)of Ball(particle)and Wall(wall)corresponding to the macroscopic parameters can be applied to the debris flow model.Through the establishment of debris flow valley model,slag dam model,slag boundary model and particle model,the true three-dimensional model of debris flow in Sigou mining area is finally combined.By monitoring the dynamic characteristics of particles,it is found that under the condition of saturation,the maximum velocity of debris flow in the study area is 3.3 m/s,and the maximum distance between erosion and deposition is 165m.(3)The four traditional disaster resistance indexes of investigation and evaluation,prediction and early warning,comprehensive treatment and emergency ability are introduced into the disaster resistance evaluation model,and the comprehensive prevention and control system of mine debris flow is established.Through empirical formula calculation and quantitative evaluation,it is found that the disaster resistance index value of debris flow in Sigou mining area is 50,the disaster resistance degree is 1.52,and the disaster resistance capacity is moderate.It provides a quantitative method for the evaluation of disaster resistance of debris flow in a single mine.This paper has a certain theoretical significance in mine debris flow risk assessment and debris flow dynamic characteristics prediction,and has a certain reference value for the prevention and control of debris flow disasters in Sigou mining area.