Comparison of three dimensional and two dimensional axisymmetric finite element analyses of a corner section of a tailings da

Zardari, Muhammad Auchar; Mattsson, Hans; Knutsson, Sven; Ormann, Linda

doi:10.24200/sci.2017.4157

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…To evaluate stability of an upstream tailings dam, advanced numerical tools based on finite element methods are generally preferable to the traditional methods based on limit equilibrium approach [see, e.g., [16][17][18][19][20][21][22][23][24][25][26][27]. At present, commercial finite element programs provide several constitutive models that cover various properties of soils in wide range of applications in geotechnical structures.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of soft tailings from different depths of a Swedish tailings dam: Results from triaxial tests

et al. 2018

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In an upstream tailings dam, loose layers might occur at different depths due to melting of frozen layers deposited during freezing temperature in Sweden. Reduced shear strength of such layers in a tailings dam might cause stability problems. Due to slow consolidation process, it is unknown, whether self-weight of a high tailings dam could have influence on strength and stiffness of soft tailings located at different depths. For numerical modelling, appropriate strength and stiffness properties of soft tailings are needed. For this purpose, loose layers in an upstream tailings dam were identified based on results of cone penetration tests.Consolidated Drained (CD) triaxial tests were conducted on undisturbed soft tailings collected from different depths of the dam. The results indicated that depth did not have considerable influence on strength and stiffness of tailings. Hardening Soil Model (HSM), at high confining pressures and axial strains underestimated stiffness of soft tailings under CD triaxial state. This study shows that: (i) proper care is needed in evaluating strength and stiffness parameters for soft tailings, and (ii) use of the HSM is likely to predict more deformations which could give an early warning before an actual failure of a tailings dam.Keywords: Soft tailings; Stress-strain behavior; Triaxial tests, Hardening Soil Model, strength and stiffness. IntroductionTailings dams may be constructed using three methods such as: upstream, downstream and centerline [1]. Tailings dams raised using upstream construction method are relatively economical as compared to ones constructed with other two methods [1]. It is generally understood that soil becomes stronger in deep layers as compared to the surface. This implies that lower layers in an embankment dam might be stronger than those at the top. This is because the strength is dependent on the confining pressure coming from the layers above. Materials StudiedThe undisturbed samples of tailings were collected from various locations of Aitik tailings dam. Void ratio and bulk density of tailings obtained from various depths are shown in Table 1. Samples were collected from those layers of the dam which were described as loose according to CPT results. Particle size distribution curves conducted by [6] showed that the tailings particles at shallow depth were more angular than those obtained from deeper depths.All samples were fully saturated having water content from 15 to 44%. The average specific gravity and bulk density of the studied tailings were 2.83 and 1.73-1.98 t/m 3 , respectively.Place Table 1 here.All tests were subject to axial strain rate of 5 × 10 −3 mm/min. The axial strains were measured indirectly by volume changes in lower chamber, and radial strains were calculated from changes in specimen height and volume. Similarly, volumetric strains were calculated from changes in back volume of specimen by measuring amount of water coming into or going out of specimen and initial sample dimensions. The axial deformations in the test s...

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Section: Introductionmentioning

confidence: 99%

Mechanical properties of soft tailings from different depths of a Swedish tailings dam: Results from triaxial tests

et al. 2018

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“…Note that the actual consolidation in the facility is two-dimensional under the assumption of plane strain or axisymmetric conditions, at least at the straight portions of the tailings impoundments and dams [10]. With regard to the use of the advanced numerical approach for a tailings dam, there have been a number of studies addressing two-dimensional numerical simulations [7,[11][12][13][14][15]] and three-dimensional numerical simulations [16][17][18]. In the study by Psarropoulos and Tsompanakis [12], an investigation on the mechanical behavior and the stability of a tailings dam under static and dynamic loading was performed.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of an Upstream Tailings Dam Subjected to Pond Filling Rates

et al. 2021

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One of the challenges in upstream tailings dam projects is to ensure the allowable rate of deposition of tailings in the pond (i.e., pond filling rate) while maintaining the stability of the dam. This is due to the fact that an upstream tailings dam is constructed by placing dikes on top of previously deposited soft tailings, which could lead to a decrease in dam stability because of the build-up of excess pore water pressure. The main purpose of this work is to investigate the effects of pond filling rates on excess pore water pressure and the stability of an upstream tailings dam by a numerical study. A finite element software was used to simulate the time-dependent pond filling process and staged dam construction under various pond filling rates. As a result, excess pore water pressure increased in each raising phase and decreased in the subsequent consolidation phase. However, some of the excess pore water pressure remained after every consolidation phase (i.e., the build-up of excess pore water pressure), which could lead to a potentially critical situation in the stability of the dam. In addition, the remaining excess pore water pressure varied depending on the pond filling rates, being larger for high filling rates and smaller for low filling rates. It is believed that the approach used in this study could be a guide for dam owners to keep a sufficiently high pond filling rate but still ensure the desirable stability of an upstream tailings dam.

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“…A few case studies have been carried out on numerical analysis of influence of seasonal changes of pore water pressures on stability of infra-structure embankments [15][16][17][18][19][20]. Stability issues of infrastructure embankments have received less attention as compared to that of embankment dams [see e.g., [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Stability of a Road Embankment Subjected to Floods

Bhutto

2021

QUESTRJ

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In the floodplains of the river Indus several road embankments have been failed due to the action of floods. The main motivation for this study is to analyse how much high floods a typical road embankment could sustain and to suggest remedies to prevent failure if the flood is exceptionally high. For this purpose, an 8 m high road embankment located in flood region of the Indus river was analysed for stability when subjected to 4 m and 7 m high floods. Numerical analysis was performed with finite element program PLAXIS 2D. The results showed that the road embankment was stable prior to occurrence of the flood. The road embankment became instable when it was subjected to flood water of 4 m. This implies that the road embankment might not withstand pressure of the flood water higher than 4 m. The analysis suggested that the road embankment could fail if the flood water is 7 m high. To stabilize the road embankment when subjected to 7 m high flood, rockfill berm was utilized on the downstream side. Optimization analysis was conducted to use minimum volume of rockfill in order to reduce costs. The findings of this study could be beneficial to practicing engineers involved in maintenance of road embankments in floodplains

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Comparison of three dimensional and two dimensional axisymmetric finite element analyses of a corner section of a tailings da

Cited by 4 publications

References 11 publications

Mechanical properties of soft tailings from different depths of a Swedish tailings dam: Results from triaxial tests

Mechanical properties of soft tailings from different depths of a Swedish tailings dam: Results from triaxial tests

Numerical Analysis of an Upstream Tailings Dam Subjected to Pond Filling Rates

Numerical Analysis of Stability of a Road Embankment Subjected to Floods

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