Study On The Mechanism Of Overtopping Dam Break Of Tailings Dam With Heavy Rainfall

Tailings dam collapse caused by heavy rainfall is the main cause of disaster of upstream tailings dam break.Overtopping dam break mechanism provides advice for the design,construction and disaster prevention of tailings dam.Used the combination of theoretical analysis and laboratory test,the breach characteristic parameters of overtopping tailings dam are quantified,and dam break process is simulated,and the mechanism of dam break is summarized.The correctness and feasibility of the model test are verified by the example of a concrete project.The following aspects of the work will be described in this paper:(1)The physical and mechanical properties of tailings particles were tested by the original samples of tailings.The tailings and river sand were enlarged 100 times by light microscope.The basic characteristics of tailings particles are compared,including general physical properties and mass properties.The preparation of different water content and different degree of compaction of the tailings sands were remodeling,and the relations between test indexes and water content or compaction of the shear strength of tailings are tested.(2)With the help of the theory of sediment movement mechanics,the force of tailings particles is analyzed theoretically.The starting randomness and the starting conditions of the tailings sand particles will be discussed.The movement form of tailings in water is described.These researches pave the way for the study of starting mechanism and propagation mechanism of the breach.(3)With an example as the background,a kind of slope displacement monitoring method of tailings dam based on physical model is put forward,and the slope displacement is monitored test by this method.At the same time,the model test is carried out in the process of overtopping failure of tailings dam,and the variation law of water level and the phreatic line in the reservoir area is studied.Through the collation of measured data in engineering,the feasibility of the model test method is verified,and conclusion can be obtained through the model test results to make up for lack of field test data,the mechanism of heavy rainfall induced by overtopping tailings dam.(4)The process and mechanism of overtopping tailings dam are analysed theoretically,the starting and expansion of the breach is described.Through the model test of tailings sand,the roughness coefficient n is amended,and the sand transport rate formula is derived.Total sediment discharge rating formula is derived.Based on the similar conditions,the dam model of heavy rainfall is tested by using the self-made interior physical model.At the same time,the experimental results are compared with the calculated results,the fitting results show good.