Study Of Block-Burst Mechanism And Scale Amplification Effect Of Mine Waste Debris Flow

In recent years,as the demand of the economic activities for mining resources is more and more large,mine waste debris flow occurs frequently,It is a serious threat to the local economic activity within the basin and the safety of the residents' life and property.In this paper,Daxicha gully in Xiaoqinling gold field of Shaanxi province was chosen as research basin,we conducted detailed field investigations on the hazard-inducing conditions and formation conditions of debris flow,we found the mine waste debris flow of Daxicha gully has typical characteristic of scale amplification after burst,such as Xiyu debris occurs in1994,it's peak flow was enlarged 2000 times,however,the applicable range of burst amplification factor is 0~3 in existing specifications,thus it is inappropriate that use this method to calculate burst amplification factor of this mine waste debris flow.On the basis of field investigation data,We launched 26 groups flume experiment with different conditions,against the experimental phenomenon,we summarizes the experiment rule,on this basis to explore block the burst mechanism and scale amplification of mine waste debris flow.The main results are as follows:(1)Starting from the flume experiment of partial blocked dams,we analysis different transport mode of mine waste by waster in different experimental conditions,we found gradient of flume has direct effect to transport mode of mine waste,And transport mode can be divided into three stages: in 5°~6°is difficult to transport stage;6°~9°is selective transport stage;9°~15°is the indiscriminate transport stage.(2)Combining transport mode of mine waste dam,we further study the rule of partial blocked dams evolve into fully blocked dams.On this basis we come up with a half experience half theory formula to calculate amplification factor of burst flow by using experimental data.(3)Starting from the flume experiment of fully blocked dams,we study the mechanism of fully blocked dams burst.In this paper,mechanism of debris flows can be divided into two aspects of internal cause and external cause,internal cause is the mechanism of block body internal damage because of seepage in impoundment stage,external cause is the mechanism of erosion by overflowing water in burst stage.(4)Combining model experiment of fully blocked dams,we further study the rule and characteristic of burst amplification effect of mine waste debris flow,we come up with three rules: amplification factor relationship with upstream flow is inversely proportional;amplification factor increased at first and then decreased in the process of burst;amplification factor has second peak in the process of change when upstream has lesser flow and gradient is smaller.