Study On The Stability Of Tailings Dam Constructed By Both Upstream And Centerline Methods

Mineral resources play a significant role in the development of the nationaleconomy, and in China, there are more than95%of the energy and85%of theindustrial raw materials originating from mineral resources. However, the grade of mostof the mineral resources in our country is relatively low, so lots of tailings would bedischarged during the beneficiation process. The tailings dam is the artificial structurebuilt for the storage of tailings, which is the biggest dangerous source in the mine. Factsshow that, a tailings dam-break can therefore constitute an enormous disaster for themining operation, and the lives and properties of the downstream residents.Consequently, it is very necessary to carry out the stability analysis and prediction studyof tailings dam.Dahongshan Longdu tailings dam is the few one which is built by both upstreamand centerline methods in China. This dissertation takes the Dahongshan tailings dam asthe research object. Based on the measurement of the tailings’ physical and mechanicalproperties, a comprehensive research method, including physical model test, theoryanalysis and numerical simulation was used to analyze and predict the stability of thetailings dam. The research results not only can provide technical support for the design,construction and production management for this dam, but also can be used forreference for the design and safe operation of similar tailings dams. The main researchwork and achieved results of this dissertation are as follow:①By modified strain control triaxial shear apparatus, the effects of particle size arestudied. Results show: the bigger median size is, the greater friction angle is but thesmaller cohesion is. The relationship presents exponential rule.②By ansys software, the distribution rules of field of seepage of the two pilingmethods are studied. Results show: there is a big difference between the exclusiveupstream method and both upstream and centerline methods, especially in the phreaticline. On the bottom of the dam, the position of phreatic line is similar, but on the top, itvaries evidently. The position of phreatic line of the dam by both upstream andcenterline methods is deeper so that the dam is safer. As a result from the field ofseepage, combining upstream with centerline methods is better than the exclusiveupstream method. ③The field of stresses of exclusive upstream method and both upstream andcenterline methods are studied. Results show: when the dam by both upstream andcenterline methods reaches+700m height level (180m), its horizontal displacement issmall(0.92m) and the verticle is big(top3.63m, settlement of unit height of dam2.02%,maximum verticle stress-2.17×10~6Pa，maximum horizonal stres-0.916×10~6Pa).④By SLIDE’s static and dynamic limit equilibrium analysis, the quantitive data ofthe stability of the dam is obtained, so as to predict its stability.1)As for the dam (height level+620.0m)by upstream method only, the stabilityfactors are: normal condition,2.071(Sweden arc method) or2.127(simplified Bishopmethod)；flooding condition,1.673(Sweden arc method) or1.695(simplified Bishopmethod)；special condition,1.282(Sweden arc method) or1.308(simplified Bishopmethod)；which all meet the standard, so the dam is safe, and the results accord withpractical conditions.2)When the dam by both upstream and centerline methods reaches+700m heightlevel (180m), the stability factors are: normal condition,1.277(Sweden arc method) or1.422(simplified Bishop method)；flooding condition,1.259(Sweden arc method) or1.406(simplified Bishop method)；special condition,1.065(Sweden arc method) or1.174(simplified Bishop method)； which all meet the standard. Under specialcondition，the stability factor is slightly higher than the standard and the rich degree issmall. So, strict measure should be taken to control and reduce the level of undergroundwater.3)According to the temporary gradient (1:3.0), the stability of dam (at+640m,+660m and+680m height level)by both upstream and centerline methods is calculated.Results meet the standard, which means it is safe. So, in the daming process, we muststrictly follow the technologe parameters including gradient (1:4.0), in case of steepslope to induce failure.4)Comparing the stability between the two methods at the same height level(+700m), that by both upstream and centerline methods is bigger. So, frm thestandpoint of security, combining upstream with centerline methods is better than theexclusive upstream method.5)The increasing capacity along the axis is3.3×104m3/m. From the capacity,combining upstream with centerline methods is better than the exclusive upstreammethod.