Influence of Layer Transition Zone on Rainfall-Induced Instability of Multilayered Slope

Abstract Although numerous studies have been paid much attention to rainfall-induced instability of multilayered slopes, the interface between layers is generally considered to be “zero thickness”, and the layer transition zone between layers is neglected. In this study, the influence of the layer transition zone on the rainfall-induced instability of multilayered slope was investigated. A model was developed to simulate the rainfall infiltration process, the distribution of pore water pressure, and the stability of multilayered slope by coupling the unsaturated seepage model and the slope stability analysis method. Based on the analysis of the multilayered slopes with the different thickness ratios of the layer transition zone, a method for determining the critical thickness of the layer transition zone was proposed. The results showed that the layer transition zone had a significant influence on the stability of multilayered slope. It was found that the presence of the layer transition zone in the multilayered slope reduced the hydraulic conductivity of the slope and increased the rate of formation of transient saturated zone, which contributed to excess pore water pressure at the toe of the slope. The analysis of the local factor of safety (LFS) showed that when the thickness ratios of the layer transition zone were between 2.5% and 5%, the corresponding hydraulic conductivity of the slope decreased by 1%-2.5% and the maximum failure area of the slope during the rainfall was 25% of the slope. Our study highlighted the importance of the layer transition zone for the rainfall-induced instability of the multilayered slope.

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Effect of Colluvial Soil Slope Fracture’s Anisotropy Characteristics on Rainwater Infiltration Process

Advances in Civil Engineering ◽

10.1155/2018/7351628 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 6

Author(s):

Ling Zeng ◽

Jie Liu ◽

Jun-hui Zhang ◽

Han-bing Bian ◽

Wei-hua Lu

Keyword(s):

Pore Water ◽

Permeability Coefficient ◽

Pore Water Pressure ◽

Water Pressure ◽

Positive Pressure ◽

Saturated Zone ◽

Infiltration Depth ◽

Infiltration Process ◽

Fracture Angle ◽

Rainwater Infiltration

The SEEP/W module of finite element software GEO-slope is used to analyze the effects of fracture depth, permeability coefficient ratio, fracture angle, and fracture number on the rainwater infiltration process. Moreover, the effect of fracture seepage anisotropy on slope stability is discussed combining with unsaturated seepage theory. The results show that the pore water pressure in the fracture increases rapidly with the rainfall until it changes from negative pressure to positive pressure. The greater the fracture depth is, the greater the pore water pressure in the fracture is, and the greater the infiltration depth at the time of rainfall stopping is. When the permeability coefficient is greater than the rainfall intensity, the permeability coefficient ratio has a great influence on the infiltration process of rainwater. The smaller the fracture angle is, the greater the maximum pore water pressure is in the fracture depth range, and the greater the depth of the positive pore water pressure is. However, with the increase of fracture angle, the infiltration depth decreases, and the range of the surface saturation area of slope increases obviously. With the increase of fracture density, the saturated positive pressure region is connected to each other in the slope. The influence range and the degree of the rainwater on the seepage field are larger and larger. There is a power relation between the saturation area and the fracture number, and also the concentration distribution of long fractures directly forms the large-connected saturated zone and raises groundwater. The range of the saturated zone and variation law of the pore water pressure under fracture seepage are obtained, which provide a reference for the parameter partition assignment of slope stability analysis under fracture seepage.

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Integrated Simulation Modeling Approach for Investigating Pore Water Pressure Induced Landslides

10.21203/rs.3.rs-1186263/v1 ◽

2022 ◽

Author(s):

Sahila Beegum ◽

P J Jainet ◽

Dawn Emil ◽

K P Sudheer ◽

Saurav Das

Keyword(s):

Pore Water ◽

Factor Of Safety ◽

Pore Water Pressure ◽

Water Pressure ◽

Simulation Models ◽

Integrated Simulation ◽

Hill Slope ◽

Slope Factor ◽

The Stability ◽

The Hill

Abstract Soil pore water pressure analysis is crucial for understanding landslide initiation and prediction. However, field-scale transient pore water pressure measurements are complex. This study investigates the integrated application of simulation models (HYDRUS-2D/3D and GeoStudio–Slope/W) to analyze pore water pressure-induced landslides. The proposed methodology is illustrated and validated using a case study (landslide in India, 2018). Model simulated pore water pressure was correlated with the stability of hillslope, and simulation results were found to be co-aligned with the actual landslide that occurred in 2018. Simulations were carried out for natural and modified hill slope geometry in the study area. The volume of water in the hill slope, temporal and spatial evolution of pore water pressure, and factor of safety were analysed. Results indicated higher stability in natural hillslope (factor of safety of 1.243) compared to modified hill slope (factor of safety of 0.946) despite a higher pore water pressure in the natural hillslope. The study demonstrates the integrated applicability of the physics-based models in analyzing the stability of hill slopes under varying pore water pressure and hill slope geometry and its accuracy in predicting future landslides.

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Unsaturated Seepage and Fluid-Solid Coupling Analysis of Rainfall Infiltration of Slope

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.3488 ◽

2011 ◽

Vol 255-260 ◽

pp. 3488-3492

Author(s):

Bao Lin Xiong ◽

Jing Song Tang ◽

Chun Jiao Lu

Keyword(s):

Pore Water ◽

Unsaturated Flow ◽

Pore Water Pressure ◽

Water Pressure ◽

Rainfall Infiltration ◽

Medium Permeability ◽

Stability Of Slope ◽

Transient Seepage ◽

The Stability ◽

Unsaturated Seepage

Rainfall is one of the main factors that influence the stability of slope. Rainfall infiltration will cause soil saturation changing and further influence pore water pressure and medium permeability coefficient. Based on porous media saturation-unsaturated flow theory, the slope transient seepage field is simulated under the conditions of rainfall infiltration. It is shown that change of pore water pressure in slope soil lag behind relative changes in rainfall conditions. As the rainfall infiltrate, unsaturated zone in top half of slope become diminution, the soil suction and shear strength reduce, so stabilization of soil slope is reduced.

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New technique for predicting the pore water pressure and evaluating the stability of rock-fill dam during impounding

Journal of Groundwater Hydrology ◽

10.5917/jagh1987.49.3 ◽

2007 ◽

Vol 49 (1) ◽

pp. 3-15

Author(s):

Yasuo YANAKA ◽

Akira TAKAHASHI ◽

Yoshinobu HOS H INO ◽

Tomokazu SUZUKI ◽

Makoto NISHIGAKI ◽

...

Keyword(s):

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

New Technique ◽

Rock Fill ◽

The Stability

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Analyses for the stability of potash tailings piles

Canadian Geotechnical Journal ◽

10.1139/t93-042 ◽

1993 ◽

Vol 30 (3) ◽

pp. 491-505 ◽

Cited By ~ 1

Author(s):

Delwyn G. Fredlund ◽

Zai Ming Zhang ◽

Karen Macdonald

Keyword(s):

Slope Stability ◽

Pore Water ◽

Pore Water Pressure ◽

Limit Equilibrium ◽

Water Pressure ◽

Field Studies ◽

Equilibrium Analysis ◽

Limit Equilibrium Analysis ◽

Dissipation Model ◽

The Stability

The stability of potash tailings piles is investigated using a pore-water pressure generation and dissipation model together with a limit equilibrium analysis. It is found that a shallow toe failure mode is generally the most applicable and that the stability may be influenced by pore-water pressure migration below the pile. It is suggested that field studies would be useful in evaluating stability in the toe region of the pile. Key words : potash tailings, slope stability, pore pressure dissipation, solutioning.

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Numerical modeling of sand drain performance — a case study of the Salter Street Bridge construction

Canadian Geotechnical Journal ◽

10.1139/t08-008 ◽

2008 ◽

Vol 45 (6) ◽

pp. 751-767 ◽

Cited By ~ 3

Author(s):

Michael J. Van Helden ◽

James A. Blatz ◽

Nelson J. Ferreira ◽

Ken Skaftfeld

Keyword(s):

Sensitivity Analysis ◽

Hydraulic Conductivity ◽

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

Axisymmetric Flow ◽

Cost Savings ◽

Local Data ◽

Undisturbed Soil ◽

Excess Pore

Several bridge crossings proposed for the Red River Floodway expansion project were recently constructed using vertical sand drains to accelerate excess pore-water pressure dissipation and settlement caused by embankment fill loading. With limited local data regarding the performance of sand drains, the calibrated model presented here addresses the need to optimize the design of sand drain configurations, maximize cost savings, and minimize construction delays for future structures. This study presents a coupled finite element embankment consolidation model calibrated against measured pore-water pressure and settlement data from the Salter Street Bridge embankment fill construction, which used vertical sand drains to dissipate excess pore-water pressures. A hydraulic conductivity modification procedure was used to simulate the axisymmetric flow conditions with a plane-strain model neglecting well resistance but incorporating the effects of a smear zone. A sensitivity analysis was performed using the calibrated model by varying the smear zone radius and hydraulic conductivity and the undisturbed soil hydraulic conductivity. The sensitivity analysis predicted that the observed behaviour was predominantly sensitive to the hydraulic conductivity of the smear zone and the surrounding soil.

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Membrane filter properties and application of the filter to undrained cyclic triaxial test of unsaturated materials

Canadian Geotechnical Journal ◽

10.1139/cgj-2016-0507 ◽

2017 ◽

Vol 54 (8) ◽

pp. 1196-1202 ◽

Cited By ~ 5

Author(s):

Hailong Wang ◽

Junichi Koseki ◽

Tomoyoshi Nishimura ◽

Yukika Miyashita

Keyword(s):

Hydraulic Conductivity ◽

Cyclic Loading ◽

Pore Water ◽

Pore Water Pressure ◽

Membrane Filter ◽

Water Pressure ◽

Characteristic Curve ◽

Loading Frequency ◽

Loading Test ◽

Pressure Plate

Properties of the membrane filter recently introduced as an alternative to the ceramic disk are revealed through diffusion and hydraulic conductivity tests. It is shown that diffusion of air through the membrane filter is significantly affected by suction magnitude and that hydraulic conductivity of the membrane filter can easily be affected by the quality of water used in the test. The application of the membrane filter to the soil-water characteristic curve tests (SWCC tests) shows that similar SWCCs can be obtained by employing pressure plate apparatuses with either the ceramic disks or the membrane filter installed, and that repeatability of the SWCC by using the membrane filter pressure plate apparatus is reasonably good. The application of the membrane filter to the undrained cyclic loading test of unsaturated sandy materials shows that the response (the duration to measure the equilibrated pore-water pressure of unsaturated materials) of the membrane filter pedestal in a modified triaxial system may be as short as ∼2 s in certain test conditions, and fairly good pore-water pressure and air pressure measurements can be obtained during undrained cyclic loading with a loading frequency of 0.1 Hz.

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

Applied Sciences ◽

10.3390/app11136044 ◽

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.

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ANALISIS STABILITAS TIMBUNAN (MAINDAM) BERDASARKAN DATA INSTRUMEN GEOTEKNIK PADA BENDUNGAN SINDANG HEULA SERANG BANTEN

Journal of Sustainable Civil Engineering (JOSCE) ◽

10.47080/josce.v3i1.1129 ◽

2021 ◽

Vol 3 (1) ◽

pp. 48-58

Author(s):

Nanang Sutisna ◽

M. Ichwanul Yusup ◽

Euis Amilia Euis Amilia

Keyword(s):

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

Field Studies ◽

Internal Erosion ◽

Embankment Dam ◽

Support Tool ◽

The Core ◽

Conducting Research ◽

The Stability

The development of science and technology has obtained supporting technology for monitoring the soil shear force and pore water pressure in the dam, the presence of shear forces against the landfill and pore water pressure through small cavities in the embankment soil in the dam body which can be detected by equipment such as inclinometer and piezometer that have been installed at predetermined points. The application of inclinometer and piezometer technology is used as a support tool for monitoring the movement of landfill and pore water pressure against dams. The embankment dam is the most complex of civilian structures and is very dangerous if damaged. When there is damage to a dam, it will cause a big disaster for the areas that are downstream of the dam. Damage or collapse of a dam can occur due to several things, including overtopping, sliding of the dam slopes (internal erosion or "piping"), and the occurrence of structural degradation of each zone. on the dam body. In the analysis of the stability of the embankment (maindam) which is based on geotechnical instrument data, it must be carried out as carefully and accurately as possible. The purpose of this analysis is to measure the early damage in the main dam (maindam). After conducting research and field studies at the Sindang Heula dam, there were several points of decline at the top of the core embankment (maindam). To find out the cause of the decline, data was taken from measuring geotechnical instruments.

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Slope Stability Analysis Under Pore-Water Pressure: A Case Study in Zarm-Rood Earthfill Dam, Iran

10.21203/rs.3.rs-498150/v1 ◽

2021 ◽

Author(s):

Mojtaba Gholamzade ◽

Ahad Bagherzadeh Khalkhali

Keyword(s):

Stability Analysis ◽

Slope Stability ◽

Pore Water ◽

Safety Factor ◽

Pore Water Pressure ◽

Water Pressure ◽

Slope Stability Analysis ◽

Operating Conditions ◽

Successful Implementation ◽

The Stability

Abstract It is well known that construction of dams or reservoirs have geomorphological impacts on the environment and could potentially accelerate the occurrence of landslides. One of the most common impact is the occurrence of new landslides and activation of the old one, which may turn into a natural disaster. Thus, controlling the stability of landslides become challenging issue specifically in the presence of f pore-water pressure. In general, the presence of water or pore-water pressure reduces the soil resistance and also leads to increase in stimulus loads, resulting in reduction of stability coefficients. In the present study, using GeoStudio SLOPE/W software, the effect of the proximity of the dam reservoir in terms of different operating conditions on the stability analysis of the landslide area of Zarm-Rood Dam is investigated. In the first step, the evaluation of internal stability of landslides and the effect of the presence of water on stability coefficients were evaluated and then the sustainable design of landslides was proposed. It was found that when extra pore-water pressure ranges from 0.2 to 0.4, safety factor is decreased by about 10%. Accordingly, safety factor is decreased by about 17% when extra pore-water pressure range from 0.4 to 0.6. This research demonstrates successful implementation of GeoStudio SLOPE/W for slope stability analysis in dam construction projects.

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