scholarly journals Ageing deformation of tailings dams in seasonally frozen soil areas under freeze-thaw cycles

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jiaxu Jin ◽  
Shiwang Li ◽  
Chenguang Song ◽  
Xinlei Zhang ◽  
Xiangfeng Lv
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Frozen Soil ◽  
Practical Significance ◽  
Permafrost Region ◽  
Tailings Dam ◽  
Freeze Thaw ◽  
Tailings Dams ◽  
Thaw Cycle

Abstract The freeze-thaw cycle is one of the important factors in inducing a dam-break in the permafrost region, so it is of great practical significance to study the mechanism of the failure deformation of tailings dams under freeze-thaw cycles. In this paper, the water-heat-force coupling model of a tailings dam considering frost-thaw damage is established, and the freeze-thaw cyclic ageing deformation of a tailings dam in a seasonally frozen soil area is studied. The correctness of the model is validated by numerical calculation. The research shows under the same water content, the compressive strength and modulus of deformation decrease with an increase in the number of freeze-thaw cycles, the cohesion and internal friction angle decrease, and the amplitude gradually decreases before becoming stable. In the process of cooling, the pore water pressure first increases and then decreases, and the pore water pressure first decreases and then increases during the heating process. The research results can provide a theoretical basis and reference values for the stability analysis of tailings dams in seasonally frozen soil areas.

Investigation on the Effects of Freeze-Thaw Action on the Pore Water Pressure Variations of Soils

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Lianhai Zhang ◽  
Wei Ma ◽  
Chengsong Yang
Keyword(s):  
Pore Water ◽  
Soil Type ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Great Influence ◽  
Frozen Soil ◽  
Silty Clay ◽  
Freeze Thaw ◽  
Soil Microstructure ◽  
Thaw Cycle

Freeze-thaw action changes soil microstructure and thus has a great influence on physical and mechanical properties of soils, which is closely correlated to pore water pressure (PWP). Herein, the PWPs of sandy soil and silty clay were measured in laboratory during freeze-thaw cycles (FTC). Experimental results showed that PWP was influenced by temperature, freeze-thaw history (i.e., number of freeze-thaw cycle), soil type and others. The PWP experienced a periodical change as temperatures periodically changes during the FTC testing, the PWP decreased during freezing and increased during thawing. Soil type has a slight influence on the variation of PWP, both in character and extent. A theoretical analysis of PWP in frozen soil was given to explain the PWP changes. In addition, the PWP depression during freezing was a major driving force for water migration. The PWP variations are highly relevant to the changes in soil microstructure such as soil particle (grain size composition and mineral composition), pore structure, and particle arrangement, which will be the focus of further research.

scholarly journals Experimental Study on Undrained Shear Properties of Saline Soil under Freeze-Thaw Cycles

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Shukai Cheng ◽  
Qing Wang ◽  
Jiaqi Wang ◽  
Yan Han
Keyword(s):  
Pore Water ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Stress Path ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Effective Stress Path ◽  
Strain Relationship

The freeze-thaw cycle is an important external factor affecting the hydromechanical characteristics of saline soil in cold regions. Due to the presence of water and salt, it has a greater impact on stability. The construction of various projects, such as ditch fills and road subgrades, has mostly used disturbed soils. Therefore, this article takes remolded saline soil in Qian’an, Jilin Province, China, as the research object to evaluate the action of freeze-thaw cycles on the critical state line, effective stress path, pore water pressure-strain relationship, stress-strain relationship, shear strength index, and other mechanical properties via a freeze-thaw cycle test and a consolidated undrained triaxial shear test (CU). The experimental results show that regardless of whether the soil specimen undergoes a freeze-thaw cycle, its stress-strain relationship shows characteristics of strain hardening, while, as the number of freeze-thaw cycles increases, the shear strength gradually decreases. As both the confining pressure and number of freeze-thaw cycles increase, the pore water pressure increases, as does the pore water pressure coefficient in shear failure. Under the action of freeze-thaw cycles, on the p ′ − q plane of the stress space, the effective stress path gradually moves to the lower left side. Both the effective stress path and the pore water pressure characteristics indicate that the degree of consolidation of the soil specimens continuously decreases as the number of freeze-thaw cycles increases. The position of the critical state line gradually lowers, and the critical state stress ratio decreases. The effective stress strength index can more accurately reflect the comprehensive influence of freeze-thaw cycles and confining pressure on the mechanical characteristics of soils than the total stress strength index. Logistic functions can be used to fit and predict the degradation law of the internal friction angle and cohesion.

Numerical Analysis of Safety on Waste-Dumping Cover-Slope out of the Tailings Dam

2014 ◽  
Vol 501-504 ◽  
pp. 178-184
Author(s):  
Kai Yang ◽  
Shu Ran Lv ◽  
Chun Xue Wang
Keyword(s):  
Production Cost ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Bottom Layer ◽  
Tailings Dam ◽  
Waste Dump ◽  
Mining Companies ◽  
Tailings Dams ◽  
Before And After ◽  
Dump Slope

Mining companies intend to solve the problem of waste dump and reduce the production cost by dumping a large number of waste soils to cover slope outside the running tailings. Therefore, in order to discuss the safety of waste dump slope covering in front of the tailings dam, numerical method was adopted to study the seepage-line change law, the pore water pressure and anti-sliding safety before and after the waste dump covering out of tailings dam. The researches show that the key to waste-dump slope safety are the drainage performance of waste dump bottom layer and the anti-sliding safety of waste dump soil. The appropriate waste dump slope work can improves the tailings dams safety and solves the waste dump problem in mining production.

scholarly journals Effects of Geosynthetic Reinforcement on Tailings Accumulation Dams

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 2986
Author(s):  
Changbo Du ◽  
Lidong Liang ◽  
Fu Yi ◽  
Ben Niu
Keyword(s):  
Comparative Analysis ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Earth Pressure ◽  
Good Choice ◽  
Tailings Dam ◽  
Test Results ◽  
Reinforcement Effect ◽  
Tailings Dams ◽  
Over Time

Owing to the complexity of current reinforcement mechanisms, test results from existing models alone cannot provide a basis for the design of new tailings dam reinforcement projects. On-site reinforced tailings accumulation dam testing is thus required to further understand the reinforcement mechanism. In this study, the influence of reinforcement on tailings dams and the variation law of pore water pressure (PWP) and internal pressure (IP) in the dam body after slurry discharge were analysed, and a comparative analysis was performed. The results showed that during the field test, the PWP and internal earth pressure of the accumulation dam after grouting gradually increased over time. Reinforcement can greatly reduce the PWP and IP of the reinforced dam; compared with geotextiles, the reinforcement effect of geogrids is slightly greater. Based on these results, we conclude that geosynthetics are a good choice for strengthening tailings accumulation dams.

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

2021 ◽  
Vol 11 (13) ◽  
pp. 6044
Author(s):  
Tan Manh Do ◽  
Jan Laue ◽  
Hans Mattsson ◽  
Qi Jia
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Tailings Dam ◽  
Filling Rate ◽  
Excess Pore Water Pressure ◽  
Finite Element Software ◽  
Consolidation Phase ◽  
The Stability ◽  
Excess Pore

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.

Variation behavior of pore-water pressure in warm frozen soil under load and its relation to deformation

2018 ◽  
Vol 15 (3) ◽  
pp. 603-614 ◽  
Author(s):  
Hu Zhang ◽  
Jianming Zhang ◽  
Ze Zhang ◽  
Mingyi Zhang ◽  
Wei Cao
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Frozen Soil

scholarly journals Analytical Solution and Application for One-Dimensional Consolidation of Tailings Dam

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Hai-ming Liu ◽  
Gan Nan ◽  
Wei Guo ◽  
Chun-he Yang ◽  
Chao Zhang
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Great Influence ◽  
Tailings Dam ◽  
Partial Differential ◽  
One Dimensional ◽  
The Stability

The pore water pressure of tailings dam has a very great influence on the stability of tailings dam. Based on the assumption of one-dimensional consolidation and small strain, the partial differential equation of pore water pressure is deduced. The obtained differential equation can be simplified based on the parameters which are constants. According to the characteristics of the tailings dam, the pore water pressure of the tailings dam can be divided into the slope dam segment, dry beach segment, and artificial lake segment. The pore water pressure is obtained through solving the partial differential equation by separation variable method. On this basis, the dissipation and accumulation of pore water pressure of the upstream tailings dam are analyzed. The example of typical tailings is introduced to elaborate the applicability of the analytic solution. What is more, the application of pore water pressure in tailings dam is discussed. The research results have important scientific and engineering application value for the stability of tailings dam.

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