scholarly journals Bioengineering Solution to Prevent Rainfall-Induced Slope Failures in Tropical Soil

Land ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 299
Author(s):  
Ujwalkumar Dashrath Patil ◽  
Austin J. Shelton III ◽  
Edriel Aquino
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Water Pressure ◽  
Matric Suction ◽  
Slope Stability Analysis ◽  
Tropical Soil ◽  
Water Retention Curve ◽  
Storm Event ◽  
Storm Events ◽  
Slope Failures

This paper presents test results of comprehensive laboratory and field-testing program efforts for the development of bioengineering solutions such as growing vegetation for protection of slopes from erosion and landslides in a tropical environmental setting. Saturated shear strength of soil was determined using direct shear tests and unsaturated soil properties, such as soil water retention curve (SWRC), were obtained using a computer-controlled hydraulic property analyzer (HYROP) system as well as a WP4C instrument. Climate data were obtained via field instrumentation and appropriate vegetation data were assumed to perform a finite element method-based transient seepage analysis and coupled slope stability analysis to test the potential of tropical hillslope to fail with and without vegetation over a period of one month. Results show that the factor of safety (FOS) for test slope considering case (a) the rainfall and bare ground, case (b) no rainfall with vegetation, and case (c) rainfall with vegetation were found to be 1.630, 1.763, and 1.650, respectively. Although FOS is marginally improved during storm events due to consideration of vegetation as compared to bare slope, this improvement in FOS is much pronounced during antecedent rainfall (i.e., long duration and small intensity) up to the first 26 days of analysis before the storm event (i.e., high intensity and short duration rainfall), which occurs on 27th day and can be instrumental in preventing slope failures. Similarly, the negative pore water pressure (i.e., matric suction) in the top layer is reduced for case (a) from −260 kPa to −40 kPa, increased for case (b) from −260 kPa to −320 kPa, and decreased for case (c) from −260 kPa to −60 kPa. The practical application of these findings is more applicable to the engineered slopes with vegetation during the dry season when the slope is more stable due to high FOS which, however, will need careful watering just to keep them healthy but prevent complete loss of developed matric suction resulting from root water uptake (RWU). In addition, the small improvement in FOS due to matric suction induced from RWU could play a key role in keeping the slope just stable during extreme storm events especially, when FOS of the bare slope is close to 1. To the best knowledge of the authors this is the first documented geotechnical study, using the tropical soil of Guam, which considers the hydro-mechanical effect of RWU-induced matric suction in slope stability analysis in a tropical setting.

scholarly journals Behavior analysis by model slope experiment of artificial rainfall

2015 ◽  
Vol 3 (6) ◽  
pp. 4159-4187
Author(s):  
M. C. Park
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Pore Water ◽  
Slope Failure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Matric Suction ◽  
Slope Stability Analysis ◽  
Model Slope ◽  
Rainfall Seepage

Abstract. In this study, we performed a model slope experiment with rainfall seepage, and the results were compared and verified with the unsaturated slope stability analysis method. In the model slope experiment, we measured the changes in water content and matric suction due to rainfall seepage, and determined the time at which the slope failure occurred and the shape of the failure. In addition, we compared and verified the changes in the factor of safety and the shape of the failure surface, which was calculated from the unsaturated slope stability analysis with the model experiment. From the results of experiment and analysis, it is concluded that the unsaturated slope stability analysis can be used to accurately analyze and predict rainfall-induced slope failure. It is also concluded that in seepage analysis, setting the initial conditions and boundary conditions is very important. If engineers will use the measured pore water pressure or matric suction, the accuracy of analysis can be enhanced. The real-time monitoring system of pore water pressure or matric suction can be used as a warning of rainfall-induced slope failure.

Modeling the unsaturated soil zone in slope stability analysis

2014 ◽  
Vol 51 (12) ◽  
pp. 1384-1398 ◽  
Author(s):  
L. L. Zhang ◽  
Delwyn G. Fredlund ◽  
Murray D. Fredlund ◽  
G. Ward Wilson
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Matric Suction ◽  
Slope Stability Analysis ◽  
Engineering Practice ◽  
Rate Of Increase ◽  
Nonlinear Shear

The linear form of the extended Mohr–Coulomb shear strength equation uses a [Formula: see text] parameter to quantify the rate of increase in shear strength relative to matric suction. When the [Formula: see text] value is unknown, a [Formula: see text] equal to 15° is sometimes used in the slope stability study to assess the influence of matric suction on the stability of a slope. In many cases, however, a [Formula: see text] value of zero is used, signifying that the effect of matric suction is ignored. Experiment results have shown that the relationship between the shear strength of an unsaturated soil and matric suction is nonlinear. Several semi-empirical estimation equations have been proposed relating the unsaturated shear strength to the soil-water characteristic curve. In this paper, the results of a study using two-dimensional slope stability analysis along with an estimated nonlinear shear strength equations is presented. The effects of using an estimated nonlinear shear strength equation for the unsaturated soils are illustrated using three example problems. Several recommendations are made for engineering practice based on the results of the example problems. If the air-entry value (AEV) of a soil is smaller than 1 kPa, the effect of matric suction on the calculated factor of safety is trivial and the [Formula: see text] value can be assumed to be zero. If the AEV of a soil is between 1 and 20 kPa, the nonlinear equations of unsaturated shear strength should be adopted. For soils with an AEV value between 20 and 200 kPa, an assumed [Formula: see text] value of 15° provides a reasonable estimation of the effects of unsaturated shear strength in most cases. For soils with an AEV greater than 200 kPa, [Formula: see text] can generally be assumed to be equal to the effective angle of internal friction, [Formula: see text], in applications where geotechnical structures have matric suctions around 100 kPa.

scholarly journals MÔ HÌNH THẤM NƯỚC MƯA PHỤC VỤ PHÂN TÍCH ỔN ĐỊNH SƯỜN DỐC KHU VỰC THỊ TRẤN CỐC PÀI - HUYỆN XÍN MẦN - TỈNH HÀ GIANG

2011 ◽  
Vol 33 (1) ◽  
pp. 78-84
Author(s):  
Nguyễn Văn Hoàng ◽  
Ứng Quốc Khang
Keyword(s):  
Soil Moisture ◽  
Stability Analysis ◽  
Slope Stability ◽  
Water Pressure ◽  
Slope Stability Analysis ◽  
Rainfall Event ◽  
Moisture Distribution ◽  
Moisture Movement ◽  
Rainwater Infiltration ◽  
Specific Distribution

Rainwater infiltration modelling for slope stability analysis in Coc Pai town-Xin Man distict-Ha Giang provinceRainfall plays an important role in formation of landslides by substantially changing the physico-mechanicalproperties of the soil such as soil weight, cohesion, friction angle, pore water pressure etc. For a given soil, thoseparameters are functions of soil moisture. Raiwater infiltration makes the change in soil moisture in space, especialliy in the depth and in time. One specific rainfall event shall give a specific rainwater infiltration and moisture distribution and therfore creates a specific distribution of physico-mechanical properties. Numerical moisture movement under given rainfall event whould give a precise moisture ditribution in soil and therefore can effectively serve the slope stability analysis and prediction. Rainwater infiltration and soil moisture movement modeling for the peak rainfall event in 2008 inCoc Pai town, Xin Man district, Ha Giang province has been carried out, which provides an important input for effectiveslope stability analysis and prediction of the area.

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.

scholarly journals Combining Satellite InSAR, Slope Units and Finite Element Modeling for Stability Analysis in Mining Waste Disposal Areas

2021 ◽  
Vol 13 (10) ◽  
pp. 2008
Author(s):  
Juan López-Vinielles ◽  
José A. Fernández-Merodo ◽  
Pablo Ezquerro ◽  
Juan C. García-Davalillo ◽  
Roberto Sarro ◽  
...  
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Slope Stability ◽  
Finite Element Modeling ◽  
Slope Stability Analysis ◽  
Radar Interferometry ◽  
Slope Failures ◽  
Element Modeling ◽  
Mining Areas ◽  
The Impact

Slope failures pose a substantial threat to mining activity due to their destructive potential and high probability of occurrence on steep slopes close to limit equilibrium conditions, which are often found both in open pits and in waste and tailing disposal facilities. The development of slope monitoring and modeling programs usually entails the exploitation of in situ and remote sensing data, together with the application of numerical modeling, and it plays an important role in the definition of prevention and mitigation measures aimed at minimizing the impact of slope failures in mining areas. In this paper, a new methodology is presented; one that combines satellite radar interferometry and 2D finite element modeling for slope stability analysis at a regional scale, and applied within slope unit polygons. Although the literature includes many studies applying radar interferometry and modeling for slope stability analysis, the addition of slope units as input data for radar interferometry and modeling purposes has, to our knowledge, not previously been reported. A former mining area in southeast Spain was studied, and the method proved useful for detecting and characterizing a large number of unstable slopes. Out of the 1959 slope units used for the spatial analysis of the radar interferometry data, 43 were unstable, with varying values of safety factor and landslide size. Out of the 43 active slope units, 21 exhibited line of sight velocities greater than the maximum error obtained through validation analysis (2.5 cm/year). Finally, this work discusses the possibility of using the results of the proposed approach to devise a proxy for landslide hazard. The proposed methodology can help to provide non-expert final users with intelligible, clear, and easily comparable information to analyze slope instabilities in different settings, and not limited to mining areas.

scholarly journals Assessing slope failure in coal mining using kinematic analysis

2021 ◽  
Vol 882 (1) ◽  
pp. 012060
Author(s):  
Bagaraja Sirait ◽  
Silti Salinita ◽  
Zulfahmi ◽  
Eko Pujianto
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Coal Mining ◽  
Kinematic Analysis ◽  
Slope Stability Analysis ◽  
Open Pit ◽  
Slope Failures ◽  
Wedge Failure ◽  
Study Results ◽  
Potential Failure

Abstract Slope stability analysis is one of the important issues in open-pit mining. It is directly influences mining operation and cost. It also becomes a primary need to prevent slope failures that disturbing production activity. Failures in slope are controlled by factors such as slope dimension, geological structures, physical and mechanical properties of slope material, and the external forces acting on the slope. This paper presents the study results on the prediction of slope stability analysis by using kinematic analysis. The study was conducted to predict the potential slope failures that could occur at the selected mine site. The site was chosen on one of the locations of open pit coal mining PT. X in East Kalimantan. Some observation points are determined to show types of failure that can occur, such as plane and wedge failure. The results show that the potential failure of the planar type occurs in 8 locations while the wedge failure occurs in 7 locations. The potential failure occur in 5 observation points, i.e: Pit-1/OP-1, Pit-2/OP-1, Pit-3/OP-1, Pit-5/OP-1, Pit-5/OP-3. Other points are in stable condition because the plane’s direction is opposite the slope direction.

scholarly journals Analisis Geologi Teknik Longsor di Desa Kuatae, Kecamatan Kota Soe, Nusa Tenggara Timur

EKSPLORIUM ◽  
2021 ◽  
Vol 42 (1) ◽  
pp. 55
Author(s):  
Heri Syaeful ◽  
Dhatu Kamajati ◽  
Yoshi Rachael ◽  
Ebenheser Damaledo
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Slope Failure ◽  
Stable State ◽  
Standard Penetration Test ◽  
Slope Stability Analysis ◽  
Geological Mapping ◽  
Base Layer ◽  
Slope Failures ◽  
High Consistency

ABSTRAK Bencana alam longsor di Desa Kuatae, Kecamatan Kota Soe sering terjadi pada musim hujan. Longsor telah menyebabkan rusaknya rumah dan infrastruktur lainnya. Penelitian longsor dilakukan dengan pemetaan geologi teknik, pengeboran geologi teknik, uji laboratorium, analisis kestabilan lereng, dan identifikasi opsi penanggulangan. Berdasarkan hasil pemetaan, longsor terjadi dalam dua model, yaitu blok batugamping terumbu yang mengalami longsor translasi di atas napal dan batulempung serta longsor rotasi pada napal yang dikontrol oleh lapisan dasar yang kontak dengan batulempung. Hasil uji penetrasi standar pada batulempung dan napal menunjukkan nilai konsistensi yang sangat tinggi. Hasil analisis kestabilan lereng menunjukkan lereng dalam keadaan stabil tapi ternyata longsor masih terjadi di beberapa tempat pada area napal dan batulempung. Hal tersebut mengindikasikan bahwa material batuan mengalami degradasi kuat geser pada beberapa kondisi. Penelitian lebih lanjut terkait degradasi material batuan, seperti sifat tahan lekang dan lempung mengembang sangat penting untuk menentukan opsi penanggulangan yang paling tepat dilakukan pada kasus longsor di Desa Kuatae.ABSTRACT Landslides in Kuatae Village, Kota Soe District often occur during the rainy season. The slope failures cause damage to houses and other infrastructures. The research of slope failure has been carried out by using engineering geological mapping, engineering geological drilling, laboratory test, slope stability analysis, and identification of countermeasure options. Based on the mapping results, slope failures occur in two models, the first one was coral limestone blocks translation failure over marl and claystone, and the second one was rotation failure on marl that controlled by the base layer which contact with claystone. The result of the standard penetration test on claystone and marl showed a very high consistency value. The slope stability analysis had shown the slope is in a stable state, but slope failure occurred in several places on the marl and claystone area. Those indicated that the material had encounter shear strength degradation under several circumstances. Further investigation on the degradation of the rock material, such as slake durability and swelling clay are very important to determine the most appropriate countermeasure option to be applied in the landslide case of Kuatae Village.

scholarly journals Including the Influence of Waves in the Overall Slope Stability Analysis of Rubble Mound Breakwaters

2016 ◽  
Author(s):  
Justine Mollaert ◽  
Abbass Tavallali
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Wave Climate ◽  
Slope Stability Analysis ◽  
Water Levels ◽  
Rubble Mound ◽  
Run Up

An offshore breakwater is designed for the construction of a LNG-terminal. For the slope stability analysis of the rubble mound breakwater the existing and the extreme wave climate are considered. Pore water pressure variations exist in the breakwater and its permeable foundation. A wave trough combined with the moment of maximum wave run-up results in a decrease and increase of the pore water pressure, respectively. Therefore, the wave actions have on overall effect on the slope stability of the breakwater. To include the wave actions in the slope stability analysis a simplified method is used. For the slope stability analysis, a specific piezometric line is determined. This piezometric line consists of a wave profile and the profile of wave run-up. The slope stability analysis are performed with GEO-SLOPE/W 2007. For the geotechnical design of the breakwater load cases of extreme and normal waves combined with, respectively, extreme and normal water levels are analysed. All the load cases which included the wave actions result in lower stability safety factors than the load cases with only still water levels. Therefore the wave actions are the determining load case for the geotechnical stability of the breakwater and it should be studied in detail.

scholarly journals Rainfall-induced landslides in the residual soil of andesitic terrain, western Japan

2011 ◽  
Vol 42 ◽  
pp. 137-152
Author(s):  
Ranjan Kumar Dahal ◽  
Shuichi Hasegawa ◽  
Minoru Yamanaka ◽  
Netra Prakash Bhandary
Keyword(s):  
Stability Analysis ◽  
Moisture Content ◽  
Slope Stability ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Stability Analysis ◽  
Surface Boundary ◽  
Residual Soil ◽  
Western Japan

Rainfall triggered landslides are frequent problems in the residual soil of andesitic terrain in western Japan. Characteristics of residual soils over bronzite andesite, procedure of in situ permeability measurement, matric suction and soil moisture content change and stability analyses considering unsaturated-saturated soils as integral system are presented in this paper. The paper highlights two landslides of small andesitic hillock of western Japan and describes modelling of rainwater seepage, slope stability analysis and contributing parameters for landsliding in andesitic terrain. For both landslides, results of geomorphological and geotechnical analyses were used as a direct input to the numerical modelling. For transient conditions, a finite element analysis was used to model the fluctuations in pore water pressure during the rainfall, with the computed hourly rainfall rate as the surface boundary condition. This was then followed by the slope stability analysis using the temporal pore water pressure distributions derived from the seepage analysis. Obtained trend for the factor of safety indicates that the most critical time step for failure was a few hours following the antecedent moisture content of previously day peak rainfall. Time of failure estimated by modelling has shown good match with time declared by eyewitnesses.

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