Safety Factor Of Slope Research Articles

Case Study of the Effect of Rainfall Infiltration on a Tunnel Underlying the Roadbed Slope with Weak Inter-Layer

It is a common type of tunnel under-cross the roadbed slope with weak inter-layer. Rainfall infiltration will cause soil softening, matric suction and strength reduction, which seriously threaten the safety of slope and tunnel. This paper presents a case where a tunnel underlying the roadbed slope with weak inter-layer in Guiyang 1# line, China. The seepage calculation model in MIDAS GTS/NX software, considering hydraulic permeability coefficient characteristic curve and soil-water characteristic curve, was used to analyze the stress and deformation of the roadbed slope and tunnel. The results reveal that rainfall infiltration has great influence on the deformation of roadbed slope with weak inter-layer and the force of internal tunnel. Slope displacement increases rapidly in the early stage and decreases in the late stage, but the absolute value of displacement increases continuously and the slope safety factor decreases gradually, which makes the slope in a dangerous state. The force of tunnel lining increases in the early stage and decreases with the recovery of soil strength after rainfall. The control effects of anchor cable and anti-slide pile reinforcement on slope sliding and tunnel stress were studied. And the anchor cable reinforcement measure is more effective on reducing slope slip and tunnel lining structure internal force.

Comparing the various slope stability methods to find the optimum method for calculating factor of slope safety

There are various slope stability analysis methods normally used to find the factor of safety of a slope. All the methods have different analysis techniques and formulation, due to which the results also varies in some cases. In this research article, all those methods are compared and the results are provided in graphical form to show the variation. The results can be used in any slope stability project to find the optimum value for factor of slope safety and hence can minimize the risk while designing any slope in hilly areas or in case of designing an earthen dam.

Finite-element upper-bound analysis of seismic slope stability considering pseudo-dynamic approach

The present study presents a novel procedure to assess the seismic slope stability, using the finite-element upper-bound method combined with the pseudo-dynamic approach. A pioneering work is performed to incorporate the pseudo-dynamic accelerations into the finite-element upper-bound analysis which combines the advantages of upper bound and finite element methods. The finite element method is principally used to discretize the domain of soil mass into finite elements, aiming to construct a kinematically admissible failure mechanism based on which the external and internal rates of work can be expressed. Based on the upper bound theorem, the upper bound formulations are derived from the virtual work rate equation, in the form of slope safety factor and limit surcharge acting on the slope crest. The problem of seeking the optimal upper bound solution is transformed to solve a linear programming problem within numerous kinematically admissible velocity fields, and this is achieved by using the interior-point algorithm implemented into the MATLAB. Pseudo-dynamic solutions are calculated and compared with the pseudo-static, limit equilibrium and FLAC results. The proposed procedure is versatile in considering the homogeneity and non-homogeneity of soil strength properties in seismic slope stability analysis. A benchmark problem with 0.5 m thick weak interlayer is discussed.

Analysis of Progressive Failure Mechanism of Rock Slope with Locked Section Based on Energy Theory

Progressive failure in rock bridges along pre-existing discontinuities is one of the predominant destruction modes of rock slopes. The monitoring and prediction of the impending progressive failure is of great significance to ensure the stability of the rock structures and the safety of the workers. The deformation and fracture of rocks are complex processes with energy evolution between rocks and the external environment. Regarding the whole slope as a system, an energy evolution equation of rock slope systems during progressive failure was established by an energy method of systemic stability. Then, considering the weakening effect of joints and the locking effect of rock bridges, a method for calculating the safety factor of rock slopes with a locked section was proposed. Finally, the energy evolution equation and the calculation method of safety factor are verified by a case study. The results show that when the energy dissipated in the progressive failure process of rock bridges is less than the energy accumulated by itself, the deformation energy stored in the slope system can make the locked section deform continuously until the damage occurs. The system energy equal to zero can be used as the critical criterion for the dynamic instability of the rock slope with locked section. The accumulated deformation energy in the slope system can promote the development of the cracks in the locked section, and the residual energy in the critical sliding state is finally released in the form of kinetic energy, which is the main reason for the progressive dynamic instability of rock slopes.

A protective measure for expansive soil slopes based on moisture content control

For expansive soil slopes, the primary failure mode is surface- or shallow-layer slide, which can occur easily under repeated rainfalls. In this investigation, a field testing program is implemented on five expansive soil slopes with different inclination subjected to artificial rainfalls, against which a numerical model is calibrated. Hydro-mechanical analysis is then conducted to estimate the factor of safety for expansive soil slopes with different pattern of fissures. A high slope inclination can increase the surface runoff, although the factor of safety decreases. It is of significance to minimize the amount of rainfall infiltration through desiccation cracks, since the increase in volumetric water content from rainfall events is more detrimental to reduce the unsaturated shear strength of soil. A conceptual framework is proposed to apply a drip irrigation system for expansive soil slopes. The volumetric water content can be maintained above a critical level to avoid the initiation of desiccation cracks. In the end, design parameters for the drip irrigation system are optimized.

Effect of pore water pressure on soil crack against safety factor of slope stability

The method used in this study is to simulate slopes that occur crack and get the influence of water saturation. The simulation is made with a computer application program, which is a program for calculating slope stability. The results of the analysis in this study found that the occurrence of cracks on the slope surface, the slope safety number will decrease when the crack is entered by water. Water entering the soil crack will cause pore water pressure which will then provide additional impetus to the slope landslide field. The greater the pore water pressure, the greater the decrease in security numbers. Besides that, the crack position from the edge of the slope has an effect on decreasing slope safety factor. A far the position of the crack from the edge of the slope increases the safety factor. The biggest decrease occurred in the position of 3 m crack from the edge of the slope. Crack positions greater than 3 m are the same. This happens because the slope failure field occurs at about 3 m from the edge of the slope.

Analisis Kestabilan Lereng Tunggal Menggunakan Metode Fellenius dan Slide v.6.0 serta Lereng Keseluruhan dengan GeoStudio 2012 pada Pit I Banko Barat PT Bukit Asam (Persero) Tbk Tanjung Enim – Sumatera Selatan

Slopes are a topography that is often found in opened pit mine that had been made by humans with the purpose of exploiting minerals that exist. Landslides can occur on any slopes that is formed due to the increase of shear stress, shear strength declining in the field of landslides or both simultaneously. Slope stability analysis performed to obtain the value of the safety factor of the field of potential landslides. The study conducted at a coal mine Pit 1 Banko Barat PT Bukit Asam (Persero) Tbk by comparing the value of a single slope safety factor Fellenius with manual method to Slide v.6.0 software and the overall slope safety factor with software GeoStudio 2012 From the analysis performed on a single slope 1 to 9, safety factor values ​​obtained below 1.25 for single slopes 1 and single slope 2 to 9 above 1.25. Of the value of the safety factor is obtained, a single slope 1 in critical condition and the single slopes 2 to 9 in stable condition. While the overall slope stability analysis using GeoStudio 2012 program obtained average value of the safety factor - average is 4.57 so the slope can be declared in a stable condition. Then there are effforts to increase the safety factor (FK) of single slopes by changing a single slope geometry previously at an angle of 55 ° to 47 ° in order to obtain the condition of the slopes in a stable condition.

APLIKASI SOFTWARE GEOSTUDIO 2007 SLOPE/WUNTUK ANALISIS KESTABILAN LERENG DI TAMBANG MUARA TIGA BESAR UTARA PT BUKIT ASAM (PERSERO) Tbk SUMATERA SELATAN

PT Bukit Asam (Persero) Tbk is one of the State Owned Enterprises engaged in coal mining. Presente of Mine Muara slopes at Muara Tiga Besar Utara would be harmful to workers and the mechanical vehicle, because the soil/ rock is likely to experience landslides or falling. This study was conducted to determine the value of slope safety factor RKAP 2017 and redesign the slopes with a safe condition. The data used in this study include the value of cohesion (c’) the angle of friction (ϕ’) and density (γ). Retrieval of research data obtained from the test results did not drainage unconsolidated triaxial (UU) and test weight of soil/rock with Paraffin Wax Method, and then did the processing of data by using Software Geostudio 2007 Slope/w to determine the value of the safety factor of the slope. Factors affecting slope instability in Mine Muara Tiga Besar Utara were the geometry of the slope, weather/climate, vibration, and physical properties and mechanics of soil/rock composed of the density (γ), ie 1.203 to 2.025 gr/cm3, the value of cohesion (c’), which is 34 to 266 kPa and the shear angle value (ϕ’), ie 17.65 to 35.210. The results of slope stability analysis indicate that the value of slope safety factor RKAP 2017 was below 1.25, so the potential occurrence of landslides, while the redesign slope slope with the security condition had a value of safety factor is above 1.25, so that no potential landslides.

Analisa Pengaruh Ground Vibration terhadap Stabilitas Low Wall Blok Muara Tiga Besar Utara Pit Timur Menggunakan Software GeoStudio 2012 di PT Bukit Asam (Persero) Tbk, Kabupaten Muara Enim

Ground vibration will produce variable Peak Particle Acceleration (PPA) which endanger the stability of the slope especially low wall. This study discusses the effect of ground vibration on the stability of the low wall and restricted in Block MTBU East Pit. While the slope analysis conducted by the method of Morgenstern-Price (1965) Manually and Software GeoStudio 2012, as well as statistical regression analysis approach in finding a relationship between the variables SD-PPA and PPA-FK. The higher the value of the PPA will lower prices Safety Factor (FK) of slope, proved to vibration FK 0.0133 g yield of 1.258 (C-C’) and 1.292 (D-D’), whereas the vibrations of 0.225 g yield of 0.771 FK (C- C’) and 0.768 (D-D’). The relationship between the scaled distance (SD) of the PPA produces non-linear relationship on a graph of power. The relationship between PPA against FK produces a linear relationship on the Section C-C’ and Section D-D’. The proposal obtained at a distance of 200 m from the blasting area 29.352 kg and at a distance of 500 m is 183.447 kg maximum load of explosives.

Combined Effect of Rainfall and Shear Strength on the Stability of Highway Embankments Made of Yazoo Clay in Mississippi

Shallow slope failure repeatedly occurs in many highway slopes in Mississippi due to the abundance of expansive Yazoo Clay. The highly plastic clay soil undergoes repetitive wet–dry cycles, which reduces the shear strength to fully soften state. The current study focused on the progressive change in shear strength and the safety factor of slopes constructed out of Yazoo Clay. Undisturbed and remolded specimens were used to determine the peak, fully softened and residual shear strength, with effective normal stresses of 25, 50, and 100 kPa. The variations in shear strength were investigated with the 2D slope stability analysis software, which uses the Finite Element Method, Plaxis 2D. A highway slope in Jackson, MS was considered as the reference slope. Different rainfall volumes, 70.8 mm (2.78 in.) to 312.4 mm (12.29 in.), with a rainfall duration (30 min–7 days) based on 100-year return periods of Jackson, MS were utilized. Furthermore, three slope ratios 2H:1V, 3H:1V and, 4H:1V were selected for this study. The safety factor of the slope was determined based on peak shear strength soil test data. Later, the topsoil layer, which gets weathered within the active zone due to the repeated wet–dry cycle, was varied to fully softened and residual shear strengths. The slope stability analysis results showed that the safety factor reduces progressively from peak to residual shear strength. In addition, the factor of safety was critical when the soil reached its fully softened shear strength for 2H:1V and 3H:1V slopes with progressive rainfall. On the other hand, the 4H:1V slope reached failure at the residual phase with the presence of rainfall.

Development of neuro-fuzzy and neuro-bee predictive models for prediction of the safety factor of eco-protection slopes

This study is aimed to investigate the surface eco-protection techniques for cohesive soil slopes along the selected Guthrie Corridor Expressway (GCE) stretch by way of analyzing a new set of intelligence techniques namely neuro-bee, artificial neural network (ANN) and neuro-fuzzy. Soil erosion and mass movement which induce landslides have become one of the disasters faced in Selangor, Malaysia causing enormous loss affecting human lives, destruction of property and the environment. Establishing and maintaining slope stability using mechanical structures are costly. Hence, biotechnical slope protection offers an alternative which is not only cost effective but also aesthetically pleasing. To reach the aim of the current study, a field investigations and numerical studies were conducted and a suitable database was prepared and established. By preparing factor of safety (FOS) as a single output parameter and a combination of the most important parameters on that, the desired models have been designed based on training and test patterns. In order to evaluate and compare the prediction precision of the developed models, a series of statistical indices, such as root mean squared error (RMSE), determination coefficient (R-square) and variance account for (VAF) are calculated. Many intelligence models with the most effective parameters on the mentioned models were developed to predict FOS. Based on the simulation results and the measured indices, it was found that the proposed neuro-fuzzy model with the lowest system error and highest R-square performs better as compared to other proposed ANN and neuro-bee models. Therefore, the neuro-fuzzy can provide a new applicable model to effectively predict the FOS of the slopes due to the fact that it is able to combine the advantages of the ANN and fuzzy inference system to indicate a high prediction capacity in solving problem of slope stability.

Study of the Stability of a Soil‐Rock Road Cutting Slope in a Permafrost Region of Hulunbuir

Due to the threat of global warming and the accelerated melting of glaciers and permafrost, the stability of slopes in permafrost regions has received an increasing amount of attention from scholars. However, research on the stability of soil‐rock road cutting slopes in high‐latitude and low‐altitude permafrost regions of the Greater Khingan Mountains in the Inner Mongolia Autonomous Region has not been reported. For this reason, a study of the stability of a slope with a high ice content in section K105 + 600 to K105 + 700 of National Highway 332 is conducted. The slope is 20 m high and the slope angle is 45°, and the risk of landslides on this slope under the action of freeze‐thaw erosion is very high. Because of this, field in situ monitoring, indoor freeze‐thaw tests, thermal parameter tests, and ABAQUS numerical simulation models are used to study the stability of the slope. After collecting the continuous temperature, moisture, settlement, and slope deformation data, it was found that the slope was undergoing dynamic changes. The creep of shallow slopes increased with the number of freeze‐thaw cycles. After approximately 150 freeze‐thaw cycles, the slope safety factor was less than 1, which means that the slope had reached the limit equilibrium state. Therefore, freeze‐thaw erosion greatly reduced the stability of the slope. Hence, the stability of the slope must be protected during its entire life cycle. This study provides a reference for the design and construction of road cutting slopes in the high‐latitude and low‐altitude permafrost regions of the Greater Khingan Mountains.

Study on the Suitable Water-Saving Irrigation Technology for Mining Areas in the Northwestern Arid Desert Regions in China

Water is the key factor to ensure plant survival in the process of ecological restoration in the coal base of China northwest deserts. On the premise of meeting the mine production and living water demands, we should take measures such as dirt wastewater treatment and water-saving irrigation to increase income and reduce expenditure and allocate limited water re-sources rationally, to provide mining area ecological restoration maximum usable water resources. The mining dump has large slope and thin soil layer and it is easy to produce surface runoff. So it is particularly important to study the irrigation technology needed to satisfy vegetation restoration, on the premise of guaranteeing not to produce surface runoff and the slope stability. In this paper, through field plot test, the suitable irrigation method for mine slope, slope surface soil moisture migration characteristics and slope stability analysis were studied. Results show that three slope ir-rigation technologies have their own advantages and disadvantages. On the whole, the effect of drip irrigation is the best, micro spray irrigation is the second, infiltrating irrigation is not ideal. The permeability of mine soil slope is very strong, the infiltration rate of the slope direction is the high-est, inverse slope infiltration rate is lowest. In the process of irrigation, with the increase of soil moisture content, slope safety factor is the decreased obviously, the whole slope surface soil moisture content is 14% for the slope stability safety threshold.

Evaluation of rock slopes susceptible to circular failures using logistic and multiple regression models

The analysis of stability of slopes is a classical problem for geotechnical engineers. In practice, many methods are available for the desired purpose, from basic kinematic analysis to two- and three-dimensional limit equilibrium analyses and numerical modeling with various user-friendly softwares. However, additional techniques are also required to provide knowledge necessary for decision-making. In this research, a reliable dataset provided by Sah et al. (1994) was used to analyze the stability evaluation of rock slopes subjected to circular failures. For this purpose, using Slide 2018 program, 44 separate limit equilibrium slope models were built for each case given in the original work. The provided material properties and slope geometries in heavily fractured and/or very weak or highly weathered rock masses were considered during the model building stage. It was found that Slide 2018 program generated dissimilar safety factors compared to those given by Sah et al. (1994) for the investigated slope cases. Binary logistic and multiple linear regression techniques were implemented in the study to promote alternative approaches for the prediction of the stability condition and safety factor (SF) of slopes excavated in heavily fractured/highly weathered rock masses. The condition of slopes (stable or failed) was predicted by binary logistic regression model with 90.9% accuracy. The SF of the slopes was estimated by a multiple linear regression model with 95.6% accuracy. It was concluded that both statistical techniques could be sufficiently used as alternative approaches to predict the stability condition and SF of rock slopes prone to circular (rotational) failures.

Failure characteristics of shallow soil slope considering surface runoff and interstitial flow

Rainfall-induced shallow landslides are widely concerned for their sudden and group occurrences and serious threat to both lives and property. In this study, a hydraulic model coupling surface runoff and interstitial flow was established to study the failure characteristics of soil slopes under heavy rainfall. Based on the coupling of surface runoff and interstitial flow, we propose a modified failure mode for shallow soil slopes. In this mode, the safety factor of the shallow soil slope is derived, while the shear force acting on the slope from surface runoff is considered, as well as the resistance from the upper and lower edges of the sliding body. Compared with the classical infinite slope failure mode, the safety factor obtained by the method proposed herein is slightly larger. Additionally, the drag effect of runoff contributed positively to slope failure, and the safety factor decreased by approximately 7% while considering the drag force in slope stability analysis. Finally, theoretical analysis is verified by simulation experiments, and the results indicate good agreement between calculated and test values for failure shape and critical runoff depth.

A rapid estimation method of the safety factor and critical stability charts for non-straight slopes with one convex fold angle

At present, almost all stability charts are designed for uniform slopes with straight surfaces. In this study, the main purpose is to provide a new stability chart analysis method, which is applicable to assess the stability of a non-straight slope with one convex fold angle. First, critical failure state charts (CFSCs) are proposed to represent the relationship among the slope height, unit weight, soil cohesion and friction angle for different slope angles when the slopes are in a critical failure state. Second, based on the CFSCs, the safety factors for any non-straight slope with one convex fold angle can be directly determined by solving quadratic equations with one unknown. Finally, the reliability and accuracy of the proposed method is tested against the limit equilibrium method (LEM) and finite-difference strength-reduction method (SRM) via 12 slope examples. The results show that the average relative errors, compared with the LEM and SRM, are 3.84% and 3.16%, respectively. Thus, it can be concluded that the proposed method has good performance in terms of calculating the FOS.

An Extension of Taylor’s φ‐Circle Method and Some Stability Charts for Submerged Slopes

Taylor’s φ‐circle method is a classical method for slope stability calculation, which has analytical solutions. Taylor derived equations in two cases separately, namely, (i) the outlet of the critical failure surface is at the slope toe and (ii) the outlet of the failure surfaces is not at the slope toe. The method is only appropriate for two conditions (without underground water table in slopes or totally submerged slopes). In this study, a general equation that unifies the equations of the two cases is proposed and partially submerged condition is introduced. The critical failure surfaces corresponding to the minimum factor of safety are determined using the computer program proposed by the authors. The general expression of the safety factor of slopes under the following four conditions is derived, namely, (i) partly submerged, (ii) completely submerged, (iii) water sudden drawdown, and (iv) water slow drawdown. The corresponding charts for practical use are available.

Landslide hazard evaluation based on linear rupture plane method

In recent years, landslide disasters have occurred frequently, making the evaluation of the susceptibility of landslide hazards a major difficulty and hot topic in current research. The current research focuses on the use of statistical models or information models to analyze landslide hazards. However, the accuracy is not high. We first study the mechanism of landslide geological disasters. Based on this, combined with multi-source geological data, a linear rupture plane method (LRP) is employed to construct the landslide hazard evaluation system. LRP regards the failure surface of the slope as an approximate plane and the section as an approximate straight line. It uses the principle of limit equilibrium to calculate the safety factor of slope. In the paper, the Ziyang area with frequent landslide disasters is taken as the research area. Choosing landslide hazard points in Ziyang County as the sample data, we select seven factors including slope height, slope angle, soil bulk density, soil cohesion, internal friction angle, precipitation intensity and seismic intensity as influencing factors. Based on the LRP, we construct an evaluation system to divide the landslide into three grades: high-risk area, low-risk area and safe area, which provides effective technical support for the early warning and prevention planning of landslide disasters.

Relationship between pit slope design and coal reserve estimation in Pit X, Muara Enim, South Sumatra Province

Mine planning is an important part of mining activity. Improper mine plan will increase production costs, non-optimal extraction of mines and safety factors that do not meet the standard. One of the most important aspects before undertaking mine plan is determining the optimal slope design as a basis for making mine pits for coal extraction. This study aims to estimate the maximum reserves that can be taken from the mine pit by taking account of the safety factor of the pit slope design. The study was conducted using drill log data and rock engineering characteristics. Analysis of slope stability is done using the Rocscience Slide V.6 software while coal reserves estimation is done using Minescape V.5.2. Slope stability analysis is modeled with several scenarios of slope angles until a single optimal slope angle is obtained, with the value of the slope safety factor that meets the safety criteria. The results showed that the maximum single slope angle in a safe pit was 52° with a safety factor of 1.266, while the coal reserves obtained with the said slope angle are 29, 965, 008 tons.

Pengendalian Longsor di Daerah Desa Sumberharjo, Kecamatan Prambanan, Kabupaten Sleman, Daerah Istimewa Yogyakarta

The landslide occurred in area of Sumberharjo Village, Prambanan Subdistrict, Regency of Sleman, Daerah Istimewa Yogyakarta Province on 28th November 2018.The landslide area have a steep slope and complex geological conditions like a cracks. The closest settlement is located 8m far from the landslide area. The purpose of the research is to determine the vulnerability of landslide zonation level based on control and trigger factor and to design technique of controlling landslide area.The methodology used in this research are survey method and field mapping. Mapping method based on the control factor which has parameter like slope, soil texture, soil thickness, weathering of rock, infiltration capacity and land use. The rainfall level parameter as a trigger factor are analyzed by secondary data. Vulnerability of landslide zonation level zoning is obtained by the scoring method based on these parameters. Determination of slope engineering by taking 3 samples of soil for laboratory analysis. The soil sampling technique is purposive sampling which is based on slope and soil texture in landslide area. The laboratory results are used to calculate slope stability using the Janbu Method. All data obtained are analyzed based on environmental conditions. The research area has 3 landslide vulnerability zones: low vulnerability level with 2756,18 m2 of area, moderate vulnerability level with 61556,92 m2 of area, and high vulnerability level with 6298,90 m2 of area. The value of safety factor on landslide area is 0.94 which is classified as unstable. Lanslide management applied in area which has high vulnerability level on landslide area by making a bench that combined with gravity wall, surface drainage, and vegetation planting such as Jati and vertiver grass. The control effort increases the value of the slope safety factor to 1.33