Slope Stability Calculations Research Articles

Controls on the Global Distribution of Martian Landslides

AbstractRecent acquisition of high‐resolution satellite imagery of the Martian surface has permitted landslides to be studied on a global scale on Mars for the first time. We apply the Scoops3D software package to compute slope stability for select regions of the Martian surface, combining calculations of slope stability with number of observed landslides (Crosta, Frattini, et al., 2018; Crosta, De Blasio, et al., 2018), as reported in a recently published inventory of Martian landslides, to understand controls on the global distribution of landslides on Mars. We find that the distribution of landslides does not simply follow the distribution of unstable slopes. In particular, there is an abundance of landslides around Tharsis, and especially in Valles Marineris and Noctis Labyrinthus, which is not explained by an abundance of unstable topography alone. We analyzed for but did not find a clear large‐scale lithologic or stratigraphic control on landslide occurrence from subsurface heterogeneities. Other possibilities to explain the increased occurrence of landslides in Tharsis include (1) thin weak unit(s) that is regionally widespread and at multiple stratigraphic levels, such as from interbedded ashes; (2) seismic activity related to the Tharsis's geological activity, and (3) possible groundwater near Valles Marineris into the Amazonian. Given the apparently young ages of many landslide deposits in Valles Marineris (Quantin et al., 2004), continued modern day analysis of lithologies in Valles Marineris and observations of Martian seismicity may act to strengthen or rebut the first two hypotheses.

Hydro-Mechanical Effects of Several Riparian Vegetation Combinations on the Streambank Stability—A Benchmark Case in Southeastern Norway

Vegetation can be used as a nature-based solution (NBS) to restore rivers and mitigate water-triggered processes along streambanks. Roots are well known to improve the overall stability of slopes through hydro-mechanical reinforcement within the rooted zone. Vegetation-based solutions require the selection of species that are most suitable for specific locations, and they are aimed at restoring the natural state and function of river systems in support of biodiversity, flood management, and landscape development. Selecting a combination of different species along different zones of the riverbank can improve the conditions for the river system with regard to biodiversity and stability. Therefore, more studies are needed to investigate how the combination of a variety of different plant species can improve the stability of the riverbank. This paper presents a methodological approach for slope stability modeling including vegetation as well as the results obtained from a series of slope stability calculations adopting the proposed methodology. The analyses were carried out for critical shallow (≤3 m deep) shear planes of ideal benchmark slopes covered with four different plant combinations—(i) only grass, (ii) grass and shrubs, (iii) only trees, and (iv) trees, shrubs, and grass—for species typically found along streams in southeastern Norway. In this desk study, two types of tree species were selected, namely Norway spruce (Picea abies) and Downy birch (Betula pubescens). The Goat willow (Salix caprea) was selected as a shrub, while a common mixed-grass was chosen as grass. Vegetation features were obtained from the literature. The methodology was used for two main cases: (1) considering only the mechanical contribution of vegetation and (2) considering both the hydrological and mechanical reinforcement of vegetation. The main outcome of the numerical modeling showed that the purely mechanical contribution of vegetation to slope stability could not be decoupled from the hydrological reinforcement in order to have a realistic assessment of the roots improvement to the stability. The most critical shear surfaces occurred below the rooted zone in all cases, and the best performance was obtained using the combinations including trees. Considering the typical climate conditions in Norway, the hydro-mechanical reinforcement was most effective in the spring and for combinations including low height vegetation (i.e., grass and shrubs). The study concludes that a mixed combination of vegetation (trees, shrubs, and grass) is the most suitable for reaching the highest hydro-mechanical reinforcement of streambanks, together with erosion protection and boosting the ecosystem biodiversity. The current study can help practitioners determine which vegetation cover combination is appropriate for improving the current stability of a streambank with restoration practices.

Correlation between CBR value and effective strength parameters for engineered fills

It is a tradition in Tanzania to use the California bearing ratio (CBR) value for the design of embankments. To assess the stability of embankments, slope stability calculations are performed, for which the effective strength parameters are needed. CBR values can be determined from the effective strength parameters based on Meyerhof’s general bearing capacity equations. Contrary to that, from a given CBR value, the effective friction angle is not easily calculated directly, as the relationship between the non-dimensional bearing capacity factors and the friction angle is complex. Moreover, only the resulting CBR value is known, not the strength contribution of the effective cohesion. Present study presents results from disturbed samples obtained from test pits and boreholes which were tested in order to determine the particle size distribution curves and Atterberg limits. On representative samples from different soil groups (AASHTO classes), CBR tests were performed to assess the quality of the fill material. Moreover, a set of isotropically consolidated, drained (CID) triaxial tests were carefully planned on the granular materials (AASHTO classes: A-2-4, A-2-6 and A-2-7) in order to investigate the relationship between CBR value and effective strength parameters of the materials when used as fill (normally consolidated conditions) at different stress levels. Based on 18 CID triaxial tests, a correlation was established which can be used directly to calculate effective strength parameters from CBR values.

ქ. თბილისის შემოვლითი რკინიგზის ტრასის გასწვრივ განვითარებული საშიში გეოლოგიური პროცესების მიმოხილვა

The slope stability calculation is quite time-consuming, which requires first selecting the correct method and then calculating the coefficient of stability using different formulas. It should also be noted that visualization of the analysis results requires a great deal of time, which is quite impractical. To solve this problem, many geotechnical computer programs have been created, which can be used to report slope stability reports in a split of a second. The most common geotechnical software in Georgia is GEO5 slope stability, which allows us to calculate slope stabilities very quickly and effectively with various methods and standards.

ქ. თბილისში რ. გოგიაშვილის ქუჩაზე განვითარებული მეწყრული სხეულის მდგრადობის ანგარიში GEO5 პროგრამის გამოყენებით

The slope stability calculation is quite time-consuming, which requires first selecting the correct method and then calculating the coefficient of stability using different formulas. It should also be noted that visualization of the analysis results requires a great deal of time, which is quite impractical. To solve this problem, many geotechnical computer programs have been created, which can be used to report slope stability reports in a split of a second. The most common geotechnical software in Georgia is GEO5 slope stability, which allows us to calculate slope stabilities very quickly and effectively with various methods and standards.

Progressive Failure of Slopes: Stochastic Simulation Based on Transition Probabilities and Markov Chains

A reliability analysis framework for the stochastic simulation of slope progressive failure is proposed in the current work. Progressive failure is addressed as a local failure propagation process that takes place along individual segments upon a critical slip surface. The probabilities of progressive failure are evaluated by transition probabilities and Markov chains theory. Slope stability computations are performed by elastoplastic finite element models. The point estimate method is used for the direct integration of geotechnical uncertainty within stability computations. For the various safety states during local failure advancement, progressive failure probabilities are expressed through a transition probability matrix. The effect of certain factors, such as the cross-correlation between shear strength components, the performance function’s probability distribution, and the initial stress ratio at rest, are also investigated and discussed.

Peningkatan Stabilitas Lereng pada Ruas Jalan Tawaeli – Toboli dengan Vegetasi/Bioengineering

Tawaeli - Toboli is one of the road that often undergo landslide. Most of these roads are in a mountainous area with high steep slopes and poor soil conditions. The road conditions worsened, especially in rainy season resulting the citizen do not know anywhere that is prone to landslides such as in Km 16 to 17. The purpose of this study was to analyze slope stability using bioengineering methods, determine the shear strength of soil without plant roots and soil with plant roots and to determine the potential for landslides that will occur. Bioengineering is used to increase the strength of the soil, and stabilize slopes and reduce erosion on slopes. The slope stability calculation using the Bishop slice method. The calculating of safety factor analyzed using the Slope / W application and manually. Soil samples were taken from 3 (three) points and the soil strength parameters, soil cohesion and friction angle, were obtained through laboratory testing. Tests were carried out using rootless and rooted soil samples. In addition, direct field observations were made to obtain slope angles and slope heights. The results showed that the parameters of soil shear strength, cohesion and friction angle increased with the presence of plant roots. The results of the slope stability analysis show that the conditions of the slope are stable at slope 1 (Km 16) and slope 3 (Km 17) with a safety factor greater than 1.5. While slope 2 (Km 16 +300) has the potential for landslides as a safety factor of less than 1.5. The use of bioengineering increases the safety factor to be greater than 1.5. The calculation of the value of the safety factor using the Slope / W program and the Bishop manual is not much different, but the calculation time with the Slope / W program is faster

Analysis of Weakening Law and Stability of Sliding Zone Soil in Thrust-Load-Induced Accumulation Landslides Triggered by Rainfall Infiltration

This study investigated the weakening model, law of mechanics parameters, and stability of the sliding zone soil associated with thrust-load-induced accumulation landslides triggered by rainfall infiltration. The spatial and morphological characteristics and rule of the sapping process were analyzed, considering the constitutive equation of the sliding zone soil, in order to establish a state curve equation for the weakening coefficient of sliding zone soil based on the “S”-shaped curve. Moreover, a formula for calculating slope stability with this failure mode was derived and applied to calculate the stability of a deformation body in Danbo reservoir, China. The results show that the sliding zone in this type of landslide exhibits steep upward and slow downward trends, and affected by rainfall infiltration, its failure develops gradually from the trailing edge to the front edge. In the constitutive equation, the weakening of soil mechanical parameters is manifested as the weakening of shear stiffness, while the “S”-shaped curve of the weakening coefficient reflects the spatial characteristics of the weakening process. The main factors affecting the accuracy of the slope stability calculation are the values of model parameters and assessment of the development characteristics and weakening stage of the sliding zone.

Simplified Calculation Method of Wharf Bank Slope Stability Considering Old Piles

Based on the requirements of durability, a simplified calculation method of wharf slope stability considering the anti-sliding effect of old piles is derived according to the allowable cracks of old piles. Firstly, the acting force between the sliding soil and the pile is assumed to be distributed in a triangle, and the position of the resultant force of each pile is determined. According to the maximum crack width limit of the old pile, the maximum bending moment that the old pile can bear is calculated. According to the maximum bending moment, the maximum horizontal force at the mud surface, where is the slip arc position, can be inversely calculated, then the maximum anti-sliding force provided by the old piles can be obtained, and the stability of wharf bank slope considering the anti-sliding effect of the old piles is checked. In the slope stability calculation of Beira fishing wharf reconstruction project in Mozambique, the simplified calculation method considering the anti-sliding effect of old piles is adopted. The stability coefficient of wharf bank slope meets the requirements, and the extra treatment of bank slope is cancelled, which saves the project investment and construction period.

Stability analysis of double V-shaped gully embankment: dimension-reduced calculation method

Slope stability is generally analyzed by a two-dimensional (2D) method, ignoring the spatial effect (SE), which no longer meets the evaluation accuracy requirement. This problem is particularly prominent for embankments built on double V-shaped gullies (E-DVSG), which is a typical but unique topography in mountainous areas. Moreover, the technical requirements for engineers will increase sharply if a three-dimensional (3D) slope stability calculation method is adopted. To tackle this issue, pragmatically, a dimension-reduced slope stability analysis method (DR-SSAM) considering the SE of the E-DVSG was proposed and verified by a case study. Specifically, the DR-SSAM obtained the 3D safety factor of the E-DVSG by using the spatial effect curves and the safety factor from the 2D model. The results showed that this method was rational and efficient for engineering applications. In addition, the SE generation mechanism and condition, along with the influences resulting from the major factors, were addressed thoroughly.

Quantifying the contribution of matric suction on changes in stability and displacement rate of a translational landslide in glaciolacustrine clay

A study of factors impacting landslide displacement rates was conducted on the Ripley Landslide within the Thompson River valley in British Columbia, Canada for the International Programme on Landslides’ project #202. Seasonal and multiyear changes in atmospheric factors cause cyclic fluctuation of matric suction in the vadose zone through changes to the in situ water content. The ingress of moisture is shown to contribute to multiyear and seasonal loss of stability causing increasing landslide displacement rates, often disregarded in slope stability calculations. However, the water content in the unsaturated zone is important, especially in semi-arid to arid climates where the water table is low and large portions of the slope are unsaturated. Additional tools for studying long-term variations in climate and seasonal changes in water content are presented. These tools are used to characterize historical climate and compare several factors that have resulted in changing landslide displacement rates and magnitude. Infiltration of precipitation and snowmelt directly contributes to matric suction loss in the head scarp and is exacerbated by the presence of tension cracks. While groundwater levels are often correlated to changing displacement rates, changes in matric suction can also influence the rates of displacement. Climatic trends over subsequent years alter the long-term soil water accumulation which impacts rates of landslide displacement. By accounting for additional strength, or potentially a loss in strength due to increasing water content, it is possible to develop a more complete understanding of the mechanisms of climate change which drive displacement rates in the translational, metastable earthen slides that dominate the Thompson River valley. These mechanisms can be applied to comparable river valleys around the world.

“Green” operation of a building - an object of cultural heritage

The aim of the study is to determine the further «green» operation of a building - an object of cultural heritage in technogenic conditions that formed in the 20-21 centuries, based on monitoring the actual engineering and geological conditions of the urban historical territory of Voronezh. The study of the engineering-geological conditions of the territory and the structures of the building was carried out in three stages. At the first stage, a reconnaissance survey was carried out to identify surface forms of manifestation of modern engineering and geological processes; at the second stage - examination and monitoring of soil properties of the foundations and the building structures; at the third stage - calculation of slope stability in the Midas GTS NX software package and selection of the optimal slope reinforcement with a retaining wall. Changes in the physical properties of soils and the violation of soil conditions on the slope of the historical territory of Voronezh during technogenic soaking of soils were revealed. Calculation of slope stability in the Midas GTS NX PC revealed the influence of the surrounding modern buildings on the deformation of the building structures -object of cultural heritage. The influence of technogenic changes in slope stability in the process of modern development on the urban historical territory on the «green» ecology, i.e. safe operation of the building - a cultural heritage site.

Slope stability analysis considering seepage and stress coupling under water level fluctuation

The reservoir water level fluctuation is an important factor inducing the reaction of pore-water pressure, seepage and at last resulting in instability and failure of the slope. A typical homogeneous slope is conducted as an example in this paper, the seepage and stress coupling effect is considered, and the slope stability calculation and analysis are carried out by using the finite element stress method. The results demonstrate that the factor of safety increases with the reservoir water level rises, and then gradually changes from decrease to stabilization. It should be noted that the factor of safety decreases slightly during the initial stage of water level rising at the speed of 0.2 m/d, which the slope will probably lose its stability. On the other, the factor of safety changes from decrease to increase along with the reservoir water level drawdown, and then gradually tends to stabilization. There is a minimum factor of safety when the water level is at about 1/4 of the slope height, and the minimum factor of safety decreases with increasing drawdown speed, just as the factor of safety decreases from 0.83 to 0.73 when the drawdown speed is increased from 0.20 m/d to 5.0 m/d.

Stateczność stoków osuwiskowych na podstawie właściwości fizyczno-mechanicznych skał i gruntów oraz pomiarów inklinometrycznych

The subject of the research was to analyse the stability of slopes with varied geological structure covered by landslide processes. Such analyses are usually carried out for landslides where structural protection and construction works are planned. An important element is proper documentation of geological and engineering soil and rock parameters, which should form the basis for stability calculations. The GEO-5 software was used for the calculations – the slope and scarp stability module. The aim of the article is to promote the methodology of documenting geological and engineering conditions in landslide areas. The general characteristics of selected research areas where inclinometer columns were installed and the methods of landslide tests were described. They were applied in accordance with the scheme: field works, laboratory tests, inclinometer measurements, and slope stability calculations for selected calculation sections. Landslides, which were analysed, are located within the Outer Flysch Carpathians, classified as tectonic units: Magura, Silesia, Podlasie, Grybów, as well as the Miechów Basin and the Carpathian Foredeep. Both surface and subsurface parts of each of the selected landslides were studied. The studies allowed the creation of a landslide model based on geological research. As a result of detailed analysis of drill cores and identified shear planes in the form of clear slickenside, the main slip planes were determined. In each landslide area, inclinometer

Stability Rating of Mine Rock Slope Based on Artificial Intelligence

Mine rock slope stability rating is the process of assessing its stability probability, analyzing its failure mode, and then determining its stability rating by location matching principle and scale matching principle, having important theoretical and practical significance in putting forward reasonable restoration suggestions. In recent years, rapidly developing artificial intelligence methods not only have the characteristics of highly nonlinear mapping, self‐organization, and self‐adaptation but also mostly apply probability optimal strategy and, hence, bypass the problem of solving function derivatives, having higher efficiency and feasibility in solving the problems of global optimal solution and local optimal solution. On the basis of summarizing and analyzing previous research works, this paper expounded the current research status and significance of mine rock slope stability rating, elaborated the development background, current status, and future challenges of artificial intelligence methods, introduced the principles of the limit equilibrium method and finite element method, constructed an artificial intelligence‐based mine rock slope stability calculation model, performed slope stability influencing factors’ analysis and optimization model parameter selection, proposed a mine rock slope stability rating algorithm based on artificial intelligence, analyzed the rating algorithm design and rating algorithm implementation, and finally conducted a case analysis and its discussion. The study results show that the artificial intelligence‐based mine rock slope stability rating method can make full use of computer advantages to have larger capacity and faster calculation speed and solve to the greatest extent the randomness, timeliness, ambiguity, and other uncertain characteristics of mine rock slope stability by a large number of random sampling for finding the optimal value of the objective function. The study results of this paper provide a reference for further research studies on the stability rating of mine rock slopes based on artificial intelligence.

SEASONAL CHANGES IN THE VALUE OF THE RESISTANCE COEFFICIENT OF THE LANDSLEND

The results of calculating the stability of a landslide-prone slope located on the river bank are presented. Additional stability studies were carried out due to the fact that, according to the results of slope calculations using various “compartments” methods, based on the construction of circular cylindrical sliding surfaces, the slope is in a stable state (tables are given containing the numerical values of the safety factors). However, in the spring-autumn period, local landslides occur on the slope. Therefore, new calculations of slope stability were carried out using a method based on the analysis of the stress state of the soil massif, which allows one to take into account the "weighing" effect of groundwater when it rises and the decrease in the strength properties of the constituent soils when they are soaked. This method is formalized in a computer program developed with the participation of one of the authors; the program has a certificate of state registration. Calculations have established that an increase in the level of groundwater to the maximum possible value reduces the values of the safety factors along the considered sliding lines by 5.9-21 %. It is shown that if the numerical values of the safety factors obtained by the methods of circular cylindrical sliding surfaces are reduced by 21 %, then some of their values will be very close to unity or even less, which resolves the above contradiction. When calculating the stability of landslide-prone soil masses, in which seasonal fluctuations of groundwater are possible, one should take into account the "weighing" effect of groundwater at the maximum level of their rise, a decrease in the physical and mechanical (strength) characteristics of soils due to their soaking and, preferably, the destabilizing effect of hydraulic heads.

Study on stability calculation method of red clay slope based on composite sliding surface

The stability of the red clay slope is poor, and the long-term exposure to the atmospheric environment is prone to instability and damage due to the dry-wet cycle. The simplified Bishop method to calculating the stability of the red clay slope is inconsistent with the actual situation. The failure characteristics and mechanism of the red clay slope are analyzed, and the existing problems of the red clay slope stability calculation are pointed out. The red clay slopes in Guizhou Province are dominated by shallow failures. Local collapse and collapse failures are very common. Overall destruction is relatively rare. A stability analysis method for red clay slopes based on composite sliding surfaces (fold-line - circular arc) is proposed. In the stability analysis of clay slope, the soil body is divided into three layers of upper, middle and lower fissure areas, and different strength indexes are selected in different areas. It is recommended to consider the effect of hydrostatic pressure generated by the water column in the fracture on the stability of the red clay slope.

Quantitative analysis of slope stability of drilling sites with complex topography in the Qiongdongnan continental slope

Due to the large slope angle and the weak strength of submarine soils, Qiongdongnan deepwater continental slopes face great instability problems. In continental slope area, evaluating the stability of the slope before drilling is important as slope instability threatens the drilling safety. Taking the Lingshui deepwater well site as an example, 2D and 3D submarine slope stability calculation models, which consider the vertical heterogeneity of soil strength, were established based on the strength reduction method and Flac3D. The vertical profile of the soil shear strength was obtained via cone penetration and geotechnical tests. The effect of returned cuttings and drilling disturbance on slope stability were analyzed, and the safety factor of the slope was calculated. In addition, the position of potential slip surfaces and the possible slip directions were analyzed. Based on this, the location of the well was determined. The results indicate that the minimum safety factor of slope, which crosses the well, is 1.32. Moreover, the risk of submarine landslide is low. One potential landslide mass exists. However, the slope near the well is stable, and the slip direction of the landslide mass does not point to the well. The returned cuttings from the borehole decrease the safety factor and increase the risk of slope instability near the well.

The influence of land use/land cover variability and rainfall intensity in triggering landslides: a back-analysis study via physically based models

The objective of this study was to use physically based models to carry out a back-analysis of the set of factors that may have influenced slope instability and the consequent development of 65 landslides in the Bengalar Stream basin, located in the Northern Region of Sao Jose dos Campos, Sao Paulo State, Brazil, associated with rainfall between March 7 and 8, 2016. Unlike other models, the FS FIORI model used in this study allowed extra variables to be added to the model that can influence hillslope stability and is associated with land use and land cover (LULC) variability. Analysis of intense short-term and accumulated long-term rainfall influence on slope instability was possible via a TRIGRS model. A comparative analysis was also carried out between a static model (FS FIORI) and a transient model (TRIGRS) which considered the factor of safety and pore pressure to be a function of precipitation and infiltration rates. Despite the differences in their hydrological components, both models were shown to present relatively similar and demonstrated stability rates coherence, according to the characteristics of each model. The FS FIORI model only classified 1.3% of the entire basin as unstable (FS ≤ 1), whereas the TRIGRS model classified 4.5% and 2.9% of the entire basin as unstable in scenarios 1 and 2, respectively. The validity and the accuracy of each model were tested via a receiver operating characteristic (ROC) curve and an area under the curve (AUC). AUC values were: 0.6552 for the FS FIORI model, and 0.7238 and 0.7186 for scenarios 1 and 2 of the TRIGRS model, respectively. The models performed well, with values considered to be acceptable. These results demonstrate an advancement in slope stability modeling studies, including conditioning factors associated with LULC for slope stability calculations.

Effect of elevated temperature on solid waste shear strength and landfill slope stability.

Slope instability occurs in landfills owing to increased internal temperatures. However, strength characteristic tests for solid waste (SW) and landfill slope stability (SS) calculations that consider temperature variations are scarce in the literature. In this study, we conducted triaxial tests on SW under a range of temperature conditions and proposed the circular slide method (CSM) for calculating SS in consideration of temperature effects. SW cohesion decreased linearly with increasing temperature, whereas the internal friction angle remained essentially unchanged. Our results showed that higher temperatures reduced the SW shear strength, changing the most dangerous sliding arc away from the slope toe. The landfill slope safety factor decreased by more than 20% with an increase of the maximum temperature from 20°C to 50°C. Reduction of the leachate level (LL) led to a decrease in the landfill high-temperature zone and the safety factor increased according to LL and temperature distribution. If cooling pipes are used to control the SW temperature, we recommend arranging the cooling pipes on the landfill liner. The proposed CSM can be used to analyse landfill SS.