Geotechnical problems related to the building of a tailings dam on sensitive varved clay

1982 ◽  
Vol 19 (4) ◽  
pp. 472-482 ◽  
Author(s):  
N. U. Capozio ◽  
J. M. Ouimet ◽  
M. M. Dupuis
Keyword(s):  
Mine Tailings ◽  
Tailings Dam ◽  
Tailings Pond ◽  
Geotechnical Investigations ◽  
The Stability ◽  
Longitudinal Cracks ◽  
Geotechnical Problems ◽  
Varved Clay ◽  
Thick Deposit

At Noranda Mines in Matagami, Quebec, the construction of a 7-m tailings dam was begun in 1974 by hydraulically depositing mine tailings across a lake. A tailings pond was thus created upstream together with a downstream sedimentation pond regulated by a weir. The presence of longitudinal cracks along the crest of the dam was observed in 1978. This generated some doubts as to the stability of the dam which rests on a 24-m thick deposit of soft sensitive varved clay.Following a first study in 1978, the fissured area was used as a berm for yet another embankment which was built upstream of the unstable zone. In order to reevaluate the stability of the structure and the consequences of an eventual dam rupture, second and third geotechnical investigations were undertaken in 1980 and 1981. This paper presents the main conclusions of these investigations. It also includes the results of borings, in-situ vane tests, and stability analyses that were used to study the problem and made the planning of remedial measures possible.

Seepage-Stability Analysis of a Mine Tailings Dam in Yunnan Province Based on ANSYS

2012 ◽  
Vol 226-228 ◽  
pp. 1406-1410
Author(s):  
Shu Qi Ma ◽  
Si Jing Cai ◽  
Miao Guo
Keyword(s):  
Stability Analysis ◽  
Mine Tailings ◽  
Yunnan Province ◽  
Reduction Method ◽  
Field Analysis ◽  
Dam Safety ◽  
Tailings Dam ◽  
Ansys Software ◽  
Safety Coefficient ◽  
The Stability

As a major hazard installation in mine the safe and effective running of a tailings dam is very important, therefore the stability analysis of tailings dam is necessary. In order to evaluate the effect of seepage on stability of mine tailings dam, in this paper, a numerical model of a tailings dam in Yunnan province was established by using ANSYS software. It was focused on the dam seepage field analysis and the seepage-stability analysis, and on using the strength reduction method to derive the safety coefficient of the tailings dam. The results were proved reasonable and could be used to provide helpful guidance of dam safety.

Rhizobia population was favoured during in situ phytoremediation of vanadium-titanium magnetite mine tailings dam using Pongamia pinnata

2019 ◽  
Vol 255 ◽  
pp. 113167 ◽  
Author(s):  
Xiumei Yu ◽  
Xia Kang ◽  
Yanmei Li ◽  
Yongliang Cui ◽  
Weiguo Tu ◽  
...  
Keyword(s):  
Mine Tailings ◽  
Pongamia Pinnata ◽  
Tailings Dam ◽  
Vanadium Titanium ◽  
Titanium Magnetite

Failure of an Embankment Founded on Varved Clay

1965 ◽  
Vol 2 (3) ◽  
pp. 234-253 ◽  
Author(s):  
K Y Lo ◽  
A G Stermac
Keyword(s):  
Stability Study ◽  
Northern Ontario ◽  
Continuous Sampling ◽  
Failure Region ◽  
Effective Stress Analysis ◽  
Order Of Magnitude ◽  
Tension Cracks ◽  
The Stability ◽  
Varved Clay

During the construction of a 19 ft. high roadway embankment at New Liskeard, Northern Ontario, on varved clay, a failure involving half the width of the embankment occurred, extending for a length of 350 ft. A comprehensive investigation was carried out, including continuous sampling and in situ vane tests at 2 ft. intervals to locate the failure zone.Stability analyses were carried out both for the failed and the stable side of the embankment, assuming different values of fill strength and depth of tension cracks.Prior to construction, 30 piezometers and 14 settlement gauges were installed at a section close to the failure region. Extrapolation of the pore-pressures measured at this location to the failure section enabled the stability study to be performed in terms of effective stresses. Analyses were also carried out for the instrumented section both in terms of total and effective stresses.The results of this study show that: (a) The discrepancy between in situ vane and laboratory tests carried out in the varved clay stratum is of the same order of magnitude as those experienced in homogeneous deposits. (b) The [Formula: see text] analysis gives approximately correct factors of safety in all the cases analysed when both fill strength and effect of tension cracks are taken into account. (c) The factors of safety given by effective stress analysis appear to be too high.The remedial measures subsequently carried out for the failure region are described.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

scholarly journals Underground Microseismic Event Monitoring and Localization within Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2830
Author(s):  
Sili Wang ◽  
Mark P. Panning ◽  
Steven D. Vance ◽  
Wenzhan Song
Keyword(s):  
Sensor Networks ◽  
Real Time ◽  
Information Needs ◽  
Localization Algorithm ◽  
Distributed Sensors ◽  
Distributed Sensor ◽  
Microseismic Events ◽  
The Stability ◽  
Stability And Accuracy

Locating underground microseismic events is important for monitoring subsurface activity and understanding the planetary subsurface evolution. Due to bandwidth limitations, especially in applications involving planetarily-distributed sensor networks, networks should be designed to perform the localization algorithm in-situ, so that only the source location information needs to be sent out, not the raw data. In this paper, we propose a decentralized Gaussian beam time-reverse imaging (GB-TRI) algorithm that can be incorporated to the distributed sensors to detect and locate underground microseismic events with reduced usage of computational resources and communication bandwidth of the network. After the in-situ distributed computation, the final real-time location result is generated and delivered. We used a real-time simulation platform to test the performance of the system. We also evaluated the stability and accuracy of our proposed GB-TRI localization algorithm using extensive experiments and tests.

scholarly journals Metagenome-assembled genomes infer potential microbial metabolism in alkaline sulphidic tailings

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Wenjun Li ◽  
Xiaofang Li
Keyword(s):  
Community Structure ◽  
Mine Tailings ◽  
Fluorescent In Situ Hybridization ◽  
High Throughput Sequencing ◽  
Microbial Consortia ◽  
Metabolic Reconstruction ◽  
Metal Release ◽  
Community Members ◽  
Oxidative Stresses

Abstract Background Mine tailings are hostile environment. It has been well documented that several microbes can inhabit such environment, and metagenomic reconstruction has successfully pinpointed their activities and community structure in acidic tailings environments. We still know little about the microbial metabolic capacities of alkaline sulphidic environment where microbial processes are critically important for the revegetation. Microbial communities therein may not only provide soil functions, but also ameliorate the environment stresses for plants’ survival. Results In this study, we detected a considerable amount of viable bacterial and archaeal cells using fluorescent in situ hybridization in alkaline sulphidic tailings from Mt Isa, Queensland. By taking advantage of high-throughput sequencing and up-to-date metagenomic binning technology, we reconstructed the microbial community structure and potential coupled iron and nitrogen metabolism pathways in the tailings. Assembly of 10 metagenome-assembled genomes (MAGs), with 5 nearly complete, was achieved. From this, detailed insights into the community metabolic capabilities was derived. Dominant microbial species were seen to possess powerful resistance systems for osmotic, metal and oxidative stresses. Additionally, these community members had metabolic capabilities for sulphide oxidation, for causing increased salinity and metal release, and for leading to N depletion. Conclusions Here our results show that a considerable amount of microbial cells inhabit the mine tailings, who possess a variety of genes for stress response. Metabolic reconstruction infers that the microbial consortia may actively accelerate the sulphide weathering and N depletion therein.

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

scholarly journals High temperature structural study of decagonal Al-Cu-Rh quasicrystal.

2014 ◽  
Vol 70 (a1) ◽  
pp. C94-C94
Author(s):  
Pawel Kuczera ◽  
Walter Steurer
Keyword(s):  
Structural Changes ◽  
Configurational Entropy ◽  
Lattice Vibrations ◽  
X Ray Diffraction ◽  
Stabilization Mechanism ◽  
X Ray ◽  
Comparative Structure ◽  
The Stability

The structure of d(ecagonal)-Al-Cu-Rh has been studied as a function of temperature by in-situ single-crystal X-ray diffraction in order to contribute to the discussion on energy or entropy stabilization of quasicrystals (QC) [1]. The experiments were performed at 293 K, 1223 K, 1153 K, 1083 K, and 1013 K. A common subset of 1460 unique reflections was used for the comparative structure refinements at each temperature. The results obtained for the HT structure refinements of d-Al-Cu-Rh QC seem to contradict a pure phasonic-entropy-based stabilization mechanism [2] for this QC. The trends observed for the ln func(I(T1 )/I(T2 )) vs.|k⊥ |^2 plots indicate that the best on-average quasiperiodic order exists between 1083 K and 1153 K, however, what that actually means is unclear. It could indicate towards a small phasonic contribution to entropy, but such contribution is not seen in the structure refinements. A rough estimation of the hypothetic phason instability temperature shows that it would be kinetically inaccessible and thus the phase transition to a 12 Å low T structure (at ~800 K) is most likely not phason-driven. Except for the obvious increase in the amplitude of the thermal motion, no other significant structural changes, in particular no sources of additional phason-related configurational entropy, were found. All structures are refined to very similar R-values, which proves that the quality of the refinement at each temperature is the same. This suggests, that concerning the stability factors, some QCs could be similar to other HT complex intermetallic phases. The experimental results clearly show that at least the ~4 Å structure of d-Al-Cu-Rh is a HT phase therefore entropy plays an important role in its stabilisation mechanism lowering the free energy. However, the main source of this entropy is probably not related to phason flips, but rather to lattice vibrations, occupational disorder unrelated to phason flips like split positions along the periodic axis.

Field evidence of resuspension in a mine tailings pond

2001 ◽  
Vol 38 (4) ◽  
pp. 796-808 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful ◽  
Mohammed H Mian
Keyword(s):  
Shear Stress ◽  
Mine Tailings ◽  
Critical Shear Stress ◽  
Field Measurements ◽  
Shear Stresses ◽  
Wind Speeds ◽  
Tailings Pond ◽  
Field Evidence ◽  
Water Cover ◽  
Solubility Of Oxygen

Flooding of tailings under shallow water covers is an effective method of decommissioning potentially acid generating mine tailings. The low diffusivity and solubility of oxygen in water are attractive features of this technology. However, wind-induced waves can resuspend flooded tailings and expose them to greater contact with dissolved oxygen, thereby increasing the potential for oxidation and acid generation. Field measurements of wind activity and waves under different water cover depths and associated resuspension for a mine tailings pond in Ontario are presented and discussed. The results show that wind speeds greater than 8 m/s above water covers that are shallower than 1 m create waves of height greater than 10 cm and bottom shear stresses greater than 0.2 Pa. Under these conditions the critical shear stress of the mine tailings was exceeded, resulting in erosion and subsequent resuspension.Key words: mine tailings, water cover, wind-induced waves, resuspension, wind speed, shear stress.

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