Study On Extreme Rainfall Induced Tailings Pond Failure And Potential Economic Damage Assessment

Tailings ponds are an essential component of normal mine production,and because their location is generally located upstream of residential areas,near traffic routes or in valley areas,a dam failure will cause significant damage to the lives and property safety of people downstream.There are many factors affecting the safety of tailing ponds,and water is an important factor.In recent years,dam failure disasters under extreme rainfall conditions have occurred frequently,so it is important to study the model test of tailing pond dam failure and potential economic loss under extreme rainfall working conditions.This paper takes a tailing pond in Gannan as the engineering background,and carries out the test of tailing pond dam failure under different extreme rainfall conditions with the help of indoor model test,to study the process of dam failure induced by different extreme rainfall conditions and the potential impact range on the downstream,and makes a quantitative study on the potential economic loss assessment of the impact range caused by dam failure disaster,the main research results are as follows.(1)Collecting information through field investigation,summarizing the geographical environment of the reservoir area and sampling the tailing sand on site,conducting geotechnical tests to determine its physical and mechanical properties,the results show that as the tailing sand particles increase,the specific gravity of the tailing sand gradually decreases,and the permeability coefficient of the tailing sand is positively correlated with the pore ratio.(2)An indoor tailings pond physical model experimental platform and artificial rainfall system were designed using similar theory to carry out model tests of tailings dam failure under different extreme rainfall conditions(50 mm/h,70 mm/h,90 mm/h,110 mm/h).The results show that the dam failure process can be divided into three stages: before(0-120s),during(120-480s)and after(480-2400s),and the dam failure damage rate is positively correlated with the rainfall intensity.In the four sets of rainfall tests,the overall change of the dam breach was "flared",the initiation mode of the breach was scour initiation,and there were two states of downhill scour and vertical slope scour during the development of the breach,and the width and depth of the final breach were positively correlated with the rainfall intensity and storage capacity.In the process of breach development,the breach changes from a longitudinal downcut to a lateral widening.The overall trend of pore water pressure changes in the test is to increase rapidly first,and then gradually decrease and stabilize after the breach,the drastic degree of pore water pressure value changes with the increase of rainfall,the time of peak pore water pressure value is different,the successive time of dam damage is consistent with the order of rainfall intensity,the change of reservoir volume will cause the change of rainfall infiltration time,this difference with the increase of rainfall intensity and This difference disappears with increasing rainfall intensity.(3)The results of downstream impacts after dam breaching under different extreme rainfall conditions show that the inundation extent and impact distance are also positively correlated with rainfall intensity and reservoir capacity.Under the same rainfall conditions,the inundation extent and impact distance of full capacity are larger and farther than those of half capacity,and the size of inundation area is not exactly consistent with the increase of rainfall intensity.The trend of the inundation range of the breached tailings sand flow with unit time can be roughly divided into three stages: rapid growth,stable growth and slow growth.The particle size of the discharged tailings sand deposited downstream of the dam body exhibited decreasing size with increasing distance,and the phenomenon of graded particle size appeared at 120 cm from the model dam site,and the loss of fine particles from the dam body during rainfall damage had a negative impact on the stability of the dam body.(4)Quantitative assessment of the dam failure disaster was carried out in terms of both loss of life and loss of house and property.The results show that: the inundation area with inundation depth of 1-2 meters accounts for the largest proportion of the total inundation area and causes the most serious economic loss;the number of people potentially affected by the dam failure disaster,the number of lives lost,the value of economic loss,and the severity level of dam failure consequences are all positively correlated with the rainfall intensity and reservoir capacity,and there is a sudden increase in each value during the rainfall process from 50 mm/h to 70 mm/h.Except for the 50 mm/h rainfall condition,which caused the loss of life less than30 people and the potential economic loss of houses within 10 million yuan,the loss of life in all other rainfall conditions exceeded 30 people and the economic loss exceeded 10 million yuan.The assessment of the risk of loss after dam failure showed that the severity level and relative loss degree were positively correlated with the rainfall intensity and reservoir capacity conditions.