Experimental Study On The Mechanism Of Tailings Pond Dam Break Under The Effect Of Seepage Failure

Tailings ponds are high potential energy hazards that can cause serious hazards downstream in the event of a dam break.According to statistics,most tailings pond dam breaks are related to water,and tailings pond accidents caused by water as an incentive account for more than 50% of the total tailings pond accidents.Seepage failure is a relatively hidden dam breaking method,which is not easy to be detected,and the dam breaking caused by it has the characteristics of strong suddenness.It is very necessary to carry out dam breaking research under this mode.In this thesis,geotechnical tests of tailings sand are carried out to obtain the basic physical and mechanical properties and seepage characteristics of tailings sand in different states;dam break models with different dense degree are established to carry out seepage failure tests to reveal the failure mechanism of the dam body under seepage failure conditions and to explore the influence of dense degree on seepage failure;according to the test results,the calculation formula of critical hydraulic gradient for seepage failure of tailings pond is deduced,and the formula is verified.The main research contents and conclusions are as follows:(1)Geotechnical tests were carried out on the tailings sand,including particle size gradation,particle specific gravity,maximum dry density,and minimum dry density,and the basic physical properties of the tailings sand were obtained;direct shear tests under different dense degree were carried out,and the results showed that the shear strength increased with increasing densities;direct shear tests under different water content conditions were carried out,and the results showed that the shear strength increased first and then decreased with increasing water content;seepage tests were carried out under different dense degree conditions,and the results showed that the permeability coefficient decreases with increasing dense degree.(2)Self-developed tailing pond penetration damage test device,in the test device stacked three different dense degree of tailing pond dam body to carry out penetration damage test,record the damage process.The dam break process of the tailings pond under seepage failure conditions is obtained through experiments;the influence law of dense degree on seepage failure is obtained by comparing the test data,that is,the greater the dense degree of dam body,the greater the hydraulic gradient required for seepage failure,the longer the time required for seepage failure,the smaller the width of the dam break area and the smaller the depth of the break zone.(3)Considering the sliding force and anti-sliding force of tailings sand,the force balance equation of tailings sand under seepage failure condition is established,and the calculation formula of critical hydraulic gradient under seepage failure condition of tailings pond is obtained theoretically.The formula is verified by the test data,which provides a scientific basis for judging whether the tailing pond is subject to seepage damage.