Experimental Study On The Seepage Failure Characteristics Of Tailings Dam

Seepage failure is an unavoidable factor affecting the stability of the tailings dam. However, there are little studies on the seepage failure in the field of tailings dam currently, let alone the sites、the forms and the development of the seepage failure. Due to this situation, the design specifications don’t have clearly defined about the impervious design of tailings dam, which produces a lot of bad influence to the safety of tailings dam. In view of this, this thesis will systematically study the characteristics and development of seepage failure in the typical parts of tailings dam, the following jobs are carried out in this dissertation:(1) This thesis summarizes the frequent sites and forms of seepage failure in tailings dam combined with actual conditions, which is based on the different characteristics of all seepage failure.(2) Developing texts about the seepage failure of tailing dam slope with sand tank model based on the theoretical analysis. Observing the forms and development of seepage failure by experiment, as well as the action law of the crucial influencing factors to the seepage failure of tailing dam slope. In addition, the seepage field will be analyzed in order to confirming the text results. The results show that dam swamp is more frequent. It will develop inward and upword continuously, which results the collapse of tailings dam. What’s more, there is a hazardous area in 1/5 of the tailings dam. Enhancing consolidation of the dam body,decreasing the slope ratio, controling the rising speed of the upstream level,and increasing the permeability coefficient of primary dam will help controling the development of seepage failure, and effectively lowering the position of the seepage failure, reduing the area and the severity of damage. Based on the test results, a modified formula which is used to distinguishing the critical condition of seepage failure is proposed:(3) Developing texts about the seepage failure of tailing dam slope with sand tank model. Observing the forms and development of seepage failure by experiment, as well as the action law of the crucial influencing factors to the seepage failure of tailing dam abutment. In addition, the seepage field will be analyzed in order to confirming the text results. The results show that the seepage failure of the dam abutment shows the evolution process of sand boiling, crack formed between the interface, and soil flowing. Enhancing consolidation of tailing sand, increasing roughness between the inferface, and slowing down the rising speed of the upstream level will make it more difficult seepage failure,and efficently control the evolution process.The critical head will increase about 7% while the porosity decreases 13%. Based on the test results, a modified formula which is used to distinguishing the critical condition of seepage failure is proposed:J=1.32 (Gs-1) (1-n)+0.21C.(4) Developing texts about the seepage failure of tailing dam slope with sand tank model. Observing the forms and development of seepage failure by experiment, as well as the action law of the crucial influencing factors to seepage failure of tailing dam abutment. In addition, the seepage field will be analyzed in order to confirming the text results. The results show that the forms of the seepage failure in tailings dam foundation mainly appears to be contact mass flow (contact rush may also accompany),the evolution process presents three steps-sand flow,certain parts of the dam collapse,and the dam body collapses massively.Enhancing consolidation of the dam body helps stopping tailings from flowing to the dam foundation,and the upstream level rising too quickly will make it bad for contact mass flow in dam foundation. The provision of "Code for engineering geological investigation of water resources and hydropower" can be used to judge the critical condition of contact mass flow.This dissertation puts forward formulas applys to tailings based on analyzing both the typical sites’ characteristics and the evolution of the seepage failure in tailings dam. Research results not only compensates the shortages of the anti-seepage design of tailings dam, but also ensures tailings dam’s safety, which has guiding significance for tailings dam.