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The Numerical Analysis Of Phreatic Line Under Tailings Dam Construction

Posted on:2011-07-20Degree:MasterType:Thesis
Country:ChinaCandidate:T L FuFull Text:PDF
GTID:2132330338981103Subject:Civil engineering
Abstract/Summary:PDF Full Text Request
Phreatic line is an important indicator in tailings dam seepage. Detailed study on variation trench for the phreatic line in the process of the the construction of the tailings dam assists to basically grasp the seepage rules for the tailings mass, as well as to guarantee the safety of the dam. Based on finite element analysis by considering effects of coupling of fluid and solid in the saturated to non-saturated tailings mass, current research probes the variation history of the phreatic line from the foundation to the elevation of 59 m in Xiyeshan tailings dam subordinated to Jinshandian Iron Mine. After that, the study on effects of the construction speed and the height of the dam on safety factor of the tailings dam is also carried out.First, the numerical simulation in ABAQUS for Cambridge centrifuge test on a road subgrade construction process in a soft soil mass is conducted. In the numerical analysis, the "Unit Add/Remove" function and the built-in Mohr-Coulomb constitutive model in the finite element software are used to numerically simulate the process of reclamation. By comparing the records of settlement and pore-water pressure from the numerical analysis with those from centrifuge test, it is found that the numerical results from ABAQUS agree with the centrifuge test data reasonably good. It indicates that ABAQUS can simulate the construction process of the tailings dam.Secondly, the numerical simulation of construction history is carried out for Xiyeshan tailings dam from the initial stage of the dam to the elevation of 59 m. It is found that the location of the numerical phreatic line is close to the monitored location given by Jinshandian Iron Mine. Meanwhile, in the analysis, comparison study is performed between two different loading patterns, in terms of gradually and overall loadings. It is found that both the displacement and stress differ from the two patterns each other, leading to the different locations of the phreatic lines for the two cases. It shows that the phreatic line for the case of gradually loading is higher that of the case of overall loading and the location of the pheratic line for the former case is closer to the monitored location than the latter case. Using the similar ABAQUS simulation model, the study on variation rules of the phreatic line is conducted for the construction period of the tailings dam from the elevation of 59 m to the design elevation and even to an extended elevation of 100 m (higher the designed elevation). It is found that the location of the phreatic line changes very litter at the lower part of the dam; by contrast, the location of phreatic line changes considerably dramatic at the upper part of the dam at a range of 6 m to 12 m under the slope of the dam. It is also found that the depth of phreatic line at the top of the newly deposited tailing mass decreases with the construction speed increasing. At the half height of the dam, the location of the phreatic line is significantly influenced by the construction speed, while at the top of the dam, the opposite is the case. The phreatic line at the upper part of the dam under every construction speed is lowest when the elevation is 80 m.Finally, finite element software SLOPE/W is used for stability analysis for Xiyeshan tailings dam. The results show that the safety factor of the tailings dam satisfies with the relevant clauses in the specification, during the construction period from current elevation to the extended height of 100 m elevation. It also shows that the safety factor decreases with the height of the dam increasing. The degree of the influence of the construction speed on the safety factor of the dam decreases with the height of the dam increasing. The variation range of the safety factor decreases when the construction speed increases.
Keywords/Search Tags:construction process, phreatic line, construction speed, safety factor
PDF Full Text Request
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