scholarly journals Seepage and Dynamic Characteristics of Carbonaceous Mudstone Coarse-Grained Soil Embankment with Different Gradations

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhong-ming He ◽  
Xiao-qu Liu ◽  
Ke Huang ◽  
Jian-ping Xiong
Keyword(s):  
Safety Factor ◽  
Dynamic Characteristics ◽  
Velocity Vector ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Coarse Grained ◽  
Seepage Velocity ◽  
Monitoring Point ◽  
Vehicle Load ◽  
Coarse Grained Soil

This study investigates the seepage and deformation characteristics of carbonaceous mudstone coarse-grained soil embankment with different gradations under the action of dynamic load and rainfall. An indoor geotechnical test is conducted, and the mechanical parameters of carbonaceous mudstone coarse-grained soil with different gradations are analyzed. A numerical calculation model of seepage and dynamic characteristics of carbonaceous mudstone coarse-grained soil embankment is established on the basis of the test data. The different effects of rainfall infiltration and vehicle load are evaluated. The seepage, settlement, and slope stability evolution characteristics of graded carbonaceous mudstone coarse-grained soil embankment slope are studied. Results show that under the condition of the same rainfall time, the greater the nonuniformity coefficient, the faster the decrease in pore water pressure of the coarse-grained soil embankment at the same monitoring point. The seepage velocity vector in the embankment is concentrated below the soil shoulder. The smaller the saturated permeability coefficient and saturated water content, the larger the seepage velocity vector. The greater the nonuniformity coefficient, the larger the coarse-grained soil embankment under vehicle load. The smaller the embankment settlement, the lower the safety factor of embankment. The safety factor decreases slowly at first and then decreases rapidly in the whole study period under the effect of dynamic wetting. The research results provide a theoretical reference for the practical engineering application of carbonaceous mudstone coarse-grained soil embankment in rainy areas.

scholarly journals Analysis of Pore Water Pressure and Piping of Hydraulic Well

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Jinman Kim ◽  
Heuisoo Han ◽  
Yoonhwa Jin
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydraulic Gradient ◽  
Water Levels ◽  
Seepage Velocity ◽  
Seepage Analysis

This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.

The Research of Pore Water Pressure Effect on the Slope Safety Factor Based on Flac

2012 ◽  
Vol 166-169 ◽  
pp. 1433-1436 ◽  
Author(s):  
Hai Bo Liu ◽  
Li Hua Zhang ◽  
Da Hao Lin
Keyword(s):  
Pore Water ◽  
Safety Factor ◽  
Pressure Effect ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Safety

On the basis of the Australian Computer Society(ACADS)`s typical questions1(a),first, regardless of the slope in the case of pore water pressure, used FLAC procedure calculate the safety factor, the result was very close to the reference answer given by ACADS, we can see the accuracy of FLAC. Then, applied to the slope of different pore water pressure, obtained safety factor under corresponding conditions, then, we found that the pore water pressure had effect on the slope safety factor, but the influence are not same, when the pore water pressure less than a certain value, the influence are very small, but, when the pore water pressure exceeded this value, the influence became very large.

Security Control Method of Loading for Surcharge Preloading Based on the Stress Path

2011 ◽  
Vol 368-373 ◽  
pp. 2795-2803
Author(s):  
Heng Hu ◽  
Yan Li ◽  
Zhi Liang Dong ◽  
Yan Luo ◽  
Gong Xin Zhang
Keyword(s):  
Pore Water ◽  
Safety Factor ◽  
Control Method ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Stress Path ◽  
Excess Pore Water Pressure ◽  
Surcharge Preloading ◽  
Security Control ◽  
Excess Pore

All the time, security control method of loading is an important research part in the surcharge preloading, which is directly related to safety of the construction process. Starting from the stress path, discussing the variation of excess pore water pressure and relationship between stress path and security, and bringing forward the control method with a safety factor Fs based on the stress path. By measuring the change of excess pore water pressure, the control method with a safety factor Fs can reflect quantitatively the security status of soil and achieve the purpose of the process control, finally the security control method including the safety factor of loading and speed control is put forward to monitor construction safety. The safety factor of loading Fs is verified and back analyzed with the finite-element software, getting the correction factor from 0.90 to 1.20.

High-resolution 3D reflection seismic investigation over a quick-clay landslide scar in southwest Sweden

Geophysics ◽  
2014 ◽  
Vol 79 (2) ◽  
pp. B97-B107 ◽  
Author(s):  
Emil Lundberg ◽  
Alireza Malehmir ◽  
Christopher Juhlin ◽  
Mehrdad Bastani ◽  
Magnus Andersson
Keyword(s):  
Seismic Data ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Geophysical Methods ◽  
Coarse Grained ◽  
Reflection Seismic ◽  
Site Investigations ◽  
Quick Clay ◽  
Triggering Mechanisms ◽  
Landslide Development

Quick-clay landslides often occur in the northern hemisphere in areas that were covered by Pleistocene glaciations. They are particularly common along the shorelines of the Göta River in southwestern Sweden. Characterization of potential landslide areas and identification of features that indicate high risk are necessary to better understand the triggering mechanisms of these events. Therefore, an intensive characterization project was initiated at the Fråstad landslide in Sweden. Part of the characterization program included the acquisition of 3D reflection seismic data to image structures in the normally consolidated sediments, as well as the bedrock topography below the landslide scar. Two seismic horizons within the glacial and postglacial sediments were observed. The shallowest seismic horizon (here, referred to as S1) corresponds to a coarse-grained layer that was previously detected by eight geotechnical boreholes located within the 3D survey area. Discontinuities in S1, mapped by the 3D reflection seismic data, occur across a zone that correlates with the landslide scar boundary, suggesting that this zone may have played a role in triggering and/or in limiting the extension of the landslide. If S1 is truncated by or mixed with clays in this zone, then the outflow of water from the permeable S1 into the clays above may have increased the amount of quick clays above this zone. The increased outflow of water may also have caused a higher pore-water pressure south of the zone, which in turn could have acted as a trigger for the landslide. We evaluated the potential of using the 3D reflection seismic method as a complement to drilling and other geophysical methods when performing landslide site investigations. We also demonstrated the importance of further investigating the relationship between 3D subsurface geometries and landslide development.

scholarly journals ANALISIS PENGARUH TEKANAN AIR PORI PADA LERENG YANG DIPERKUAT DENGAN GEOTEKSTIL

2021 ◽  
Vol 4 (1) ◽  
pp. 139
Author(s):  
Satria Seprianto ◽  
Andryan Suhendra
Keyword(s):  
Tensile Strength ◽  
Pore Water ◽  
Safety Factor ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Reinforcement ◽  
Slope Safety

ABSTRACTInfrastructure development in Indonesia is growing  rapidly. With the large number of infrastructure developments in various slope topographies, it is one of the locations that is part of this development. The slope area is prone to landslides so that strengthening is necessary. One of the reinforcement that can be done is with geotextiles. In its installation, it is necessary to calculate the correct length and strength of the geotextile for reinforcement. The tensile strength and length of the geotextile as well as the parameters of the embankment affect the safety factor of slope construction. One of the factors being considered is the pore water pressure which reduces the slope strength. So that the results of this study will show how much the influence of pore water pressure on slope reinforcement with geotextiles. After analysis, it was found that the increase of pore water pressure resulted in decreasing of slope safety factor.ABSTRAKPembangunan infarstruktur di Indonesia berkembang sangat pesat. Dengan banyaknya pembangunan imfrastruktur di berbagai topografi lereng menjadi salah satu lokasi yang menjadi bagian dalam pembangunan tersebut. Daerah lereng rawan akan terjadinya longsor sehingga perlu dilakukan perkuatan. Salah perkuatan yang dapat dilakukan adalah dengan geotekstil. Dalam pemasangannya dibutuhkan perhitungan panjang dan kuat geotekstil yang tepat untuk perkuatan. Kuat tarik dan panjang geotekstil serta parameter tanah timbunan mempengaruhi faktor keamanan konstruksi lereng. Salah satu faktor yang dipertimbangkan adalah tekanan air pori yang menjadi penurunan kekuatan lereng. Sehingga hasil studi ini akan menunjukkan seberapa besar pengaruh tekanan air pori pada perkuatan lereng dengang geotekstil. Setelah dilakukannya analisis didapatkan bahwa kenaikan tekanan air pori mengakibatkan penurunan nilai faktor keamanan lereng.

scholarly journals Unsaturated seepage and stability of double-layer slope under rainfall infiltration

2021 ◽  
Vol 248 ◽  
pp. 03024
Author(s):  
Yuan Zhang ◽  
Haifeng Lu
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Safety Factor ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Parameters ◽  
Lag Period ◽  
Rainfall Patterns ◽  
Continuous Rainfall ◽  
Slope Safety

Taking a homogeneous double-layer soil slope as an example, the SEEP/W module and SLOPE/W module in the finite element analysis software GeoStudio were used in this paper. Then, the changes of pore water pressure and stability under different rainfall patterns and soil parameters were studied. Finally, the variation curves of pore water pressure and slope safety factor with rainfall time were obtained. The results show that: Soil parameters a and m are directly proportional to the slope safety factor, while n is inversely proportional to the slope safety factor. Under the condition of continuous rainfall, the decreasing rate of slope safety factor is directly proportional to the rainfall intensity.Under different rainfall patterns, the continuous rainfall in the advanced and normal rainfall patterns will cause the slope stability to decline and then gradually recover, while delayed and averaged rainfall patterns rainfall will cause the slope stability to decline continuously.In addition, there is a lag period in the change of slope safety factor, and the whole lag period lasts about 6 hours. During the lag period, the pore water pressure inside the soil began to decrease, while the slope safety factor continued to decrease. The safety factor starts to recover after the lag period ends.

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

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.

Stability Analysis of Soil Slope under Strong Earthquake

2014 ◽  
Vol 602-605 ◽  
pp. 598-601 ◽  
Author(s):  
Tie Jun Tao ◽  
En An Chi ◽  
Ming Sheng Zhao ◽  
Qiang Kang
Keyword(s):  
Pore Water ◽  
Safety Factor ◽  
Water Depth ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Time History ◽  
Element Model ◽  
The Stability ◽  
Dynamic Time ◽  
Minimum Safety Factor

Based on the finite element model of slope, the stability of sand slope are studied. The results show that The pore water pressure shows increase trend, while the excess pore water pressure shows decreasing trend with the increase of the water depth. With the increase of the the water depth, safety factor of slope calculated by quasi static reduces to 0.193 from 2.366, which reduces 12.26times. The minimum safety factor calculated by dynamic time history is less than that by quasi static method, which shows that there is some limitations of the quasi static method.Without considering the groundwater, the destruction of slope is mainly the circular shearing damage through the slope toe, while the destruction is not yet through the slope toe, but from a point on the front of slope.

Use of recycled crushed concrete and Secudrain in capillary barriers for slope stabilization

2013 ◽  
Vol 50 (6) ◽  
pp. 662-673 ◽  
Author(s):  
H. Rahardjo ◽  
V.A. Santoso ◽  
E.C. Leong ◽  
Y.S. Ng ◽  
C.P.H. Tam ◽  
...  
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Coarse Grained ◽  
Residual Soil ◽  
Soil Slope ◽  
Capillary Barrier ◽  
Concrete Aggregates ◽  
Crushed Concrete ◽  
Residual Soil Slope

A capillary barrier is a two-layer cover system having distinct hydraulic properties to minimize water infiltration into the underlying soil by utilizing unsaturated soil mechanics principles. In this study, a capillary barrier system was designed as a cover system for a residual soil slope to maintain stability of the slope by minimizing infiltration during heavy rainfalls in the tropics. The capillary barrier system (CBS) was constructed using fine sand as the fine-grained layer and recycled crushed concrete aggregates as the coarse-grained layer. The coarse-grained layer is commonly constructed using gravels or granite chips. However, due to scarcity of aggregates and in consideration of environmental sustainability, recycled crushed concrete aggregates were used as the coarse-grained layer in this project. The suitability of recycled crushed concrete aggregates as a material within the coarse-grained layer of a CBS is subject to the hydraulic property requirement. For comparison, another CBS was constructed using fine sand as the fine-grained layer and a geosynthetic (Secudrain) as the coarse-grained layer. The performance of each constructed CBS on the residual soil slope was monitored using tensiometers installed at different depths — from 0.6 to 1.8 m below the slope surface — and a rainfall gauge mounted on the slope. An adjacent original slope without the CBS was also instrumented using tensiometers and piezometers to investigate the performance and effectiveness of the CBS in reducing rainwater infiltration and maintaining negative pore-water pressures in the slope. Real-time monitoring systems were developed to examine pore-water pressure, rainfall, and groundwater level in the slopes over a 1 year period. Characteristics of pore-water pressure distributions in the residual soil slope under a CBS with recycled crushed concrete aggregates and in the original slope during typical rainfalls are highlighted and compared. The measurement results show that the CBS was effective in minimizing rainwater infiltration and therefore, maintaining stability of the slope.

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