scholarly journals Sensitivity Analyses of the Seepage and Stability of Layered Rock Slope Based on the Anisotropy of Hydraulic Conductivity: A Case Study in the Pulang Region of Southwestern China

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2314 ◽  
Author(s):  
Chengzhi Xia ◽  
Guangyin Lu ◽  
Dongxin Bai ◽  
Ziqiang Zhu ◽  
Shuai Luo ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Factor Of Safety ◽  
Rock Slope ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Sensitivity Analyses ◽  
Southwestern China ◽  
Anisotropy Ratio ◽  
Rock Slopes ◽  
Layered Rock

In the study of the seepage characteristics of layered rock slope under rainfall conditions, the majority of previous research has considered the hydraulic conduction to be isotropic, or only considered the anisotropy ratio of the hydraulic conductivity, ignoring the anisotropy angle. In the current study, a layered rock slope in the Pulang region was selected as an example. Then, based on the fitting parameters of the Van Genuchten model, pore water pressure sensitivity analyses of the layered rock slope were carried out. The anisotropy ratio and anisotropy angle were used to analyze the sensitivity of the seepage and stability of the layered rock slopes. The results show that as the anisotropy angle of hydraulic conductivity of layered rock slope decreased, the maximum volume water content of surface (MWCS) of layered rock slope gradually increased. Additionally, as the anisotropy ratio decreased and the anisotropy angle increased, the rising heights of the groundwater (RHG) of layered rock slope gradually increased. When the hydraulic conduction of layered rock slope was considered isotropic, the factor of safety (FS) tended to be overestimated. As the anisotropy ratio decreased and the anisotropy angle increased, the factor of safety (FS) of layered rock slope decreased. Prevention should be the objective for rock slopes with larger dip angles in the bedding plane in the Pulang region. This study provides feasible schemes for the evaluation of the seepage and stability of layered rock slopes in Pulang region of southwestern China.

scholarly journals Deformation and Stability Characteristics of Layered Rock Slope Affected by Rainfall Based on Anisotropy of Strength and Hydraulic Conductivity

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3056
Author(s):  
Chengzhi Xia ◽  
Guangyin Lu ◽  
Ziqiang Zhu ◽  
Lianrong Wu ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Factor Of Safety ◽  
Rock Slope ◽  
Horizontal Displacement ◽  
Field Monitoring ◽  
Monitoring Data ◽  
Anisotropy Ratio ◽  
Conductivity Anisotropy ◽  
Layered Rock ◽  
Dip Angle

The strength and hydraulic conductivity anisotropy of rock slopes have a great impact on the slope stability. This study took a layered rock slope in Pulang, Southwestern China as a case study. The strength conversion equations of the seriously weathered rock mass were proposed. Then, considering the anisotropy ratio and anisotropy angle (dip angle of bedding plane) of strength and hydraulic conductivity, the deformation and stability characteristics of rock slope were calculated and compared with field monitoring data. The results showed that the sensitivity analysis of strength and hydraulic conductivity anisotropy could successfully predict the occurrence time, horizontal displacement (HD), and the scope of the rock landslide. When the anisotropy ratio was 0.01 and the dip angle was 30°, the calculated HD and scope of the landslide were consistent with the field monitoring data, which verified the feasibility of the strength conversion equations. The maximum horizontal displacement (MHD) reached the maximum value at the dip angle of 30°, and the MHD reached the minimum value at the dip angle of 60°. When the dip angle was 30°, the overall factor of safety (FS) and the minimum factor of safety (MFS) of the rock slope were the smallest. By assuming that the layered rock slope was homogeneous, the HD and MHD would be underestimated and FS and MFS would be overestimated. The obtained results are likely to provide a theoretical basis for the prediction and monitoring of layered rock landslides.

scholarly journals Integrated Simulation Modeling Approach for Investigating Pore Water Pressure Induced Landslides

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.

scholarly journals Effect of different parameters of heterogeneous dams on safety factor using the neural network. Case study: Marvan dam

2019 ◽  
Vol 32 (02) ◽  
pp. 126-138
Author(s):  
B. Beiranvand ◽  
A. Mohammadzade ◽  
M. Komasi
Keyword(s):  
Neural Network ◽  
Factor Of Safety ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Drainage System ◽  
Friction Angle ◽  
The Body ◽  
The Neural Network ◽  
The Cost

The drainage system is used to guide the flow of water in the earth dams. Construction of drainage in the dam body to collect and direct the drainage formed in the dam body to keep the slope dry and prevent the increase of pore water pressure in the body. One of the main goals of the designers is to find the minimum factor of safety and, consequently, reduce the cost of construction. In this study, the Marvak dam is modeled with the actual characteristics of the materials in the Geostudio software, and with the change in the dimensions of the drain, the material and the slope of the dam body, the minimum Factor of safety of the dam is obtained. In order to predict the minimum Factor of safety, a two-layer neural network has been used. With the training of the neural network based on the data obtained from heterogeneous dams, a minimum Factor of safety has been extracted for optimization of drainage. Finally, it was determined that the internal friction angle of the body material and the slope of the dam have the greatest effect on the dam factor of safety.

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

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Zhi Dou ◽  
Yimin Liu ◽  
Xueyi Zhang ◽  
Yashan Wang ◽  
Zhou Chen ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Transition Zone ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Layer Transition ◽  
Infiltration Process ◽  
Local Factor ◽  
The Stability ◽  
Different Thickness

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.

Numerical modelling of coupled seepage-deformation subjected to rainfall infiltration in unsaturated slope

2020 ◽  
Vol 17 (6) ◽  
pp. 867-875
Author(s):  
Edgar Jr Joe ◽  
Nazri Ali ◽  
Siti Norafida Jusoh
Keyword(s):  
Numerical Modelling ◽  
Design Methodology ◽  
Factor Of Safety ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Monitoring ◽  
Rainfall Infiltration ◽  
Deformation Analysis ◽  
Content Type ◽  
Fully Coupled

Purpose This study aims to propose another alternative numerical modelling tool, i.e. ABAQUS, to simulate a fully coupled seepage-deformation analysis in unsaturated slope subjected to rainfall infiltration. Design/methodology/approach The effect of rainfall infiltration on the response of pore water pressure and factor of safety has been analysed and discussed. The results of this study have also been validated based on the results of field monitoring and previous numerical modelling. Findings The results from ABAQUS show a better agreement with those from field monitoring compared to other numerical modelling tools. Originality/value The procedures adopted in this study can be adopted and used as a guide to model similar slope problems in ABAQUS.

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

2008 ◽  
Vol 45 (6) ◽  
pp. 751-767 ◽  
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.

Research of Slope Stability Analysis Considering Rainfall Infiltration

2012 ◽  
Vol 204-208 ◽  
pp. 487-491
Author(s):  
Jian Hua Liu ◽  
Zhi Min Chen ◽  
Wei He
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Rock Slope ◽  
Rainfall Intensity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rainfall Infiltration ◽  
Safety Coefficient ◽  
Rainfall Duration ◽  
Unsaturated Seepage

Based on the saturated-unsaturated seepage theory and considering soil-hydraulic permeability coefficient characteristic curves of rock slope, the variation of suction in unsaturated region and transient saturated zone formation of rock slope were analyzed. Combined with engineering example, the strength reduction methods were adopted to analyzing the rock slope stability influence factors considering unsaturated seepage with different rainfall intensity and duration. The results show that the flow domain owing to rainfall infiltration mainly appears surface layer region of slope. The rainfall infiltration caused the groundwater level rise, the rising of transient pore water pressure and the fall of suction in unsaturated region caused the slope stability decrease. The rainfall intensity and duration have obvious influence on slope stability, and in the same rainfall duration condition, the safety coefficient of slope decreases with the accretion of rainfall intensity. With the rainfall duration increasing, the water in soil has more deep infiltration, the water content and pore water pressure was higher in the same high position, the decreasing of suction caused the safety coefficient of slope has more reduce.

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

2017 ◽  
Vol 54 (8) ◽  
pp. 1196-1202 ◽  
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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