Stability Of Steep Slopes Research Articles

A Slope Structural Plane Extraction Method Based on Geo-AINet Ensemble Learning with UAV Images

In the construction of large-scale water conservancy and hydropower transportation projects, the rock mass structural information is often used to evaluate and analyze various engineering geological problems such as high and steep slope stability, dam abutment stability, and natural rock landslide geological disasters. The complex shape and extremely irregular distribution of the structural planes make it challenging to identify and extract automatically. This study proposes a method for extracting structural planes from UAV images based on Geo-AINet ensemble learning. The UAV images of the slope are first used to generate a dense point cloud through a pipeline of SfM and PMVS; then, the multiple geological semantics, including color and texture from the image and local geological occurrence and surface roughness from the dense point cloud, are integrated with Geo-AINet for ensemble learning to obtain a set of semantic blocks; finally, the accurate extraction of structural planes is achieved through a multi-semantic hierarchical clustering strategy. Experimental results show that the structural planes extracted by the proposed method perform better integrity and edge adherence than that extracted by the AINet algorithm. In comparison with the results from the laser point cloud, the geological occurrence differences are less than three degrees, which proves the reliability of the results. This study widens the scope for surveying and mapping using remote sensing in engineering geological applications.

3D Discretized Rotational Failure Mechanism for Slope Stability Analysis

The kinematical approach of limit analysis has been historically employed to assess slope stability in the geotechnical community, for which most three-dimensional (3D) failure mechanisms are generally based on a composite of multiple common geometrical bodies. Although these failure mechanisms are straightforward, they may not perform well for slopes that involve multilayered soils with heterogeneous shear strength parameters. This paper aims at proposing a new 3D failure mechanism for steep slopes using a spatial discretization technique. The proposed failure mechanism is composed of a large number of elemental blocks that are generated point by point obeying the kinematically admissible velocity field and the normality condition. The discretization scheme makes it possible to simplify the calculations of internal energy dissipations and external work rates on the failure mechanism when both the soil properties and external loadings are spatially changing. The performance of the proposed method is illustrated to examine the stability of steep slopes in homogeneous soils, multilayer soils, and spatially variable soils, showing good agreements with previously published results and numerical modelings.

Forest Area Changes in Cinque Terre National Park in the Last 80 Years. Consequences on Landslides and Forest Fire Risks

Cinque Terre, one of the most important Italian cultural landscapes, has not been spared from depopulation and agricultural abandonment processes, that involved many rural areas in Europe, as a consequence of socio-economic transformations that occurred after WWII. Depopulation of rural areas, especially in mountains or in terraced areas, caused significant environmental consequences, such as the decrease of biodiversity, the landscape homogenization, the increase of hydrogeological and forest fires risks. Cinque Terre National Park (5TNP) was established in 1999, and, differently from other Italian National Parks, not just for protecting natural habitats, but mainly to preserve, restore and valorize the historical terraced landscape. Moreover, the area is a UNESCO cultural landscape site and it is partly protected by three Sites of Community Importance. The research intended to investigate the transformations that have affected forested areas inside the 5TNP in the period 1936–2018, also highlighting the connections with hydrogeological and forest fires risks, as a support for the Park planning strategies and the conservation of the UNESCO site. Results highlighted that 37% of the current forests are the consequence of dry stones terraces abandonment that occurred in the twentieth century, with negative effects on the stability of steep slopes, hydrogeological risk, forest fires and on the conservation of a unique cultural landscape. This confirms the current national trend showing no deforestation occurring, but rather a continuous increase of forests on abandoned land. While 5TNP policies and actions are effectively aimed at pursuing an equilibrium between cultivated areas and forests, the Sites of Community Importance located inside the Park mainly focuses on the conservation of “natural habitats”, even if the current vegetation is also the result of secondary successions on former cultivated land. The research highlighted the need to valorize “cultural values” in forest planning as well as the importance of forest history for an accurate planning of forest resources in protected areas.

Study on High and Steep Slope Stability and Slope Angle Optimization of Open-Pit Based on Limit Equilibrium and Numerical Simulation

The stability of open-pit slope is related to mine safety, especially for high and steep slope. In order to obtain the design slope stability and slope angle optimization of K mine open-pit in Myanmar, limit equilibrium analysis method and three-dimensional numerical simulation are used to carry out the study on the slope stability. The results show that: (1) The safety factor of the designed slope is larger than the allowable safety factor by using the limit equilibrium analysis, which belongs to the stable slope. Some areas can be optimized for design. (2) Through three-dimensional numerical analysis, the design slope and the optimized slope are both stable. The area with large deformation of the optimized slope is mainly concentrated in the area of 562 m level moderately weathered pyroclastic rock in area A and 560 m level moderately weathered rock in area B. The calculation results of three-dimensional numerical simulation are basically consistent with the results of the limit equilibrium analysis. (3) Compared with the designed slope, the potential sliding surface position of the optimized slope is lower. The safety factor is smaller, but larger than the allowable safety factor. The shape of the sliding surface of the whole slope is nearly circular arc. The sliding mode of the slope is circular arc sliding. (4) The reasonable slope angle of different engineering geological divisions of the open-pit slope of K mine is determined. The overall slope angle of area A is ≤ 46°. The overall slope angle of area B is ≤ 44°. The overall slope angle of area C is ≤ 45°. The overall slope angle of area D is ≤ 50°. The research results can provide reference for mine safety production.

Icelandic permafrost dynamics since the Last Glacial Maximum – model results and geomorphological implications

Iceland’s periglacial realm is one of the most dynamic on the planet, with active geomorphological processes and high weathering rates of young bedrock resulting in high sediment yields and ongoing mass movement. Permafrost is discontinuous in Iceland’s highlands and mountains over c. 800 m a.s.l, and sporadic in palsa mires in the central highlands. During the late Pleistocene and Holocene, Iceland’s periglacial environment varied considerably in time and space, dominated by glacial fluctuations and periglacial processes. To evaluate the dynamics of permafrost in Iceland since the last deglaciation, we use the output of a coupled climate/ice sheet model to force a transient permafrost model (CryoGRID 2) from the Last Glacial Maximum (LGM) through to the present. We find that permafrost was widespread across the deglaciated areas of western, northern and eastern Iceland after the LGM, and that up to 20% of Iceland’s terrestrial area was underlain by permafrost throughout the late Pleistocene. This influenced geomorphological processes and landform generation: the early collapse of the marine-based ice sheet together with the aggradation of permafrost in these zones initiated the formation of abundant and now relict rock glaciers across coastal margins. Permafrost degraded rapidly after the Younger Dryas, with a marked impact on slope stability. Permafrost that formed during the Little Ice Age is again thawing rapidly, and an escalation in slope failure and mass-movement might be currently underway. Our study demonstrates that large regions of Iceland have been underlain by permafrost for millennia, facilitating landform development and influencing the stability of steep slopes.

Impacts of land use policy on the recovery of mountain catchments from acidification

Watersheds in mountainous regions provide water resources available to large downstream areas. Acidification of mountain waters leads to problems in water quality with impacts to drinking water supply and biodiversity conservation. Effects of the land use policy, air pollution and forest canopy on acidification of headwater catchments in the Jizera Mountains were studied in the period of 1982–2015. The archive of LANDSAT imagery and a field inventory was used to reconstruct changes in the vegetative cover. The atmospheric deposition of acidic substances (sulphate, nitrate, and ammonia) in studied catchments was approximated by a spatial interpolation. The acid atmospheric load culminated in the 1980s. The Helsinki protocol on the reduction of sulphur emissions lead to a reduced open field deposition of sulphur, but, the atmospheric deposition of sulphur and nitrogen is also controlled by the vegetative canopy. A drop in the acid load and a recovery of surface waters from acidification were observed with the harvest of spruce forests. The existing land use policy, institutes of ‘protected headwater area’ and ‘zones of hygienic protection’ (Water Act 138/1973) were ineffective in this situation. In a catchment scale, the proposed scenario of structured forestry zones (respecting riparian buffers, stability of steep slopes, significant fog drip areas, peat spots) can decrease the annual load of sulphur and nitrogen by approx. 30%.

Impact of Crack on Stability of Slope with Linearly Increasing Undrained Strength

This paper presents a procedure for assessment of the impact of tension crack on stability of slope in clays with linearly increasing undrained strength. The procedure is based on the limit equilibrium method with variational extremization. The distribution of the normal stress over slip surface is mathematically obtained for slopes in clays with the linearly increasing undrained strength and then used to determine the tension crack for clays with zero tensile strength. The seismic effect is also included using the pseudostatic approach. Closed-form solutions to the minimum safety factor and the maximum crack depth can be derived and given in the form of chart for convenient use. The results demonstrate a significant effect of the tension crack on the stability of steep slopes, especially for strong seismic conditions. In this situation, neglecting the impact of tension crack in traditional ϕ=0 analyses may overestimate the slope safety. The most adverse location of the tension crack can be also determined and presented in the charts, which may be useful in designing reinforcements and remedial measures for slope stabilization.

ANALISIS STABILITAS LERENG DI KAKI GUNUNG SUMBING

Balesari village of Windusari sub-district of Magelang regency located at the foot of the mountain SUMBING with a height<strong> </strong>of 350 to 1050 meters above sea level. This research was conducted by analyse the stability of steep slopes through soil physical properties using Bishop Morgenstern method. The analytical approach used is deterministic two-dimensional. Primary data obtained from measurements of the slope directly by using Theodolite and took soil samples at each location. The soil samples were tested at the Laboratory of Soil Mechanics to get the parameters of soil physical properties such as grain gradation, void ratio ( ), the soil volume weight ( ), the friction angle ( ), the value of cohesion (c). The result of study states the value of soil cohesion in the hamlet Mojo categorized loam, while in the hamlet of Malanggaten categorized clay loam. The results of soil physical properties shows the value of the Factor of safety (F) at the measurement point in the hamlet of Mojo and Malanggaten are 0.89, 0.31 and 0.41 respectively. Thus the stability of the slope in the village is not safe.

Joint exploration of regional importance of possibilistic and probabilistic uncertainty in stability analysis

Stability analysis generally relies on the estimate of failure probability P. When information is scarce, incomplete, imprecise or vague, this estimate is imprecise. To represent epistemic uncertainty, possibility distributions have shown to be a more flexible tool than probability distributions. The joint propagation of possibilistic and probabilistic information can rely on more advanced techniques such as the classical random sampling of the cumulative probability distribution F and of the intervals from the possibility distributions π. The imprecise probability P is then associated with a random interval, which can be summarized by a pair of indicators bounding it. In the present paper, we propose a graphical tool to explore the sensitivity on these indicators. This is conducted by means of the contribution to sample probability of failure plot based on the ordering of the randomly generated levels of confidence associated with the quantiles of F and to the α-cuts of π. This presents several advantages: (1) the contribution of both types of uncertainty, aleatoric and epistemic, can be compared in a unique setting; (2) the analysis is conducted in a post-processing step, i.e. at no extra computational cost; (3) it allows highlighting the regions of the quantiles and of the nested intervals which contribute the most to the bounds of P. The method is applied on two case studies (a mine pillar and a steep slope stability analysis) to investigate the necessity for extra data acquisition on parameters whose imprecision can hardly be modelled by probabilities due to the scarcity of the available information (respectively the extraction ratio and the cliff geometry).

Permafrost in Alpine Rock Faces from Jotunheimen and Hurrungane, Southern Norway

ABSTRACTThe warming and degradation of mountain permafrost within alpine areas is an important process influencing the stability of steep slopes and rock faces. In the mountains of southern Norway (Jotunheimen), an increase in ground temperatures has been recorded during the last 12 years, and modelling studies suggest the possible degradation of most mountain permafrost during the 21st century. To better estimate the thermal state of permafrost in steep rock walls in Norway, five temperature loggers were installed in 2009 and 2010, measuring the near‐surface rock wall temperatures in vertical rock faces. Surface temperatures in rock walls in Norway are on average higher than the ambient air temperature, by about 1 °C in shaded faces to more than 3 °C in faces with other aspects. An aspect dependency of rock wall temperatures is mainly visible during summer, with deviations of up to 4 °C between north‐ and south‐facing walls. Based on a 1D transient heat flow model, the active‐layer thickness at the study sites was estimated to be in the range of 3 m to 5 m at 2300 m asl and 1600 m asl, respectively. As a first‐order approximation, a spatial regression model based on elevation and potential incoming short‐wave radiation was used to estimate the lower limit and distribution of rock wall permafrost under present‐day conditions and for a scenario with average air temperatures increased by 2 °C. Today, the lower limit ranges from 1200–1300 m asl to 1600–1700 m asl in north‐ and south‐facing rock walls, respectively. With a warming of 2 °C, the lower limit would increase to about 1700 m and 2100 m, respectively, which corresponds to a loss of 70 per cent of the rock walls underlain by permafrost today in the study area, where more than half of the rock walls potentially containing permafrost are situated below 1800 m asl. Copyright © 2014 John Wiley & Sons, Ltd.

급경사지 평가요소 분석을 통한 평가표 개선방안 연구

재해 및 재난을 예방하고 급경사지 붕괴 위험요인이나 기능 및 성능저하를 평가하기 위해 급경사지 평가표를 작성하여 활용하고 있다. 하지만 급경사지 평가표의 항목이 기관별로 상이하고 동일한 항목일지라도 평가배점이 다르고 조사자의 주관적 의견이 반영되어 통일성 및 신뢰성을 확보하기 어려운 실정이다. 이에 본 연구에서는 국내 급경사지 평가방법 중 대표적인 5가지 평가방법을 분석, 문제점을 도출 및 보완하여 급경사지 관리주체 담당자 누구나 현장에서 손쉽게 적용할 수 있는 평가항목 및 평가법을 제안하였다. 또한, 제시된 평가표 및 기존의 평가표를 붕괴된 급경사지에 적용하여 신뢰성 검증작업을 수행하였다. There are stability checklists for steep slopes in order to evaluate their function and performance especially when they are initiated to move. It is, however, difficult to ensure the reliability of the checklist because of the diversity of institutions which use the checklist, the subjectivity of observer's opinion, and the difference of scores in items even though they indicate same characteristics. In this study, therefore, an improved checklist and methodology is proposed, which is based on the modification of five representative steep slope stability checklists from different institutions. This may help for non-professionals to determine overall stability of steep slopes. Also, a verification is performed by applying it to identified collapsed steep slopes in order to get a reliability of the proposed checklist compared to existing checklists.

High and Steep Slope Stability Analysis Induced by Goaf Based on 3D Fast Lagrangian Analysis of Continua

Contraposing a lead-zinc ore in yunnan province, Adopting FLAC3D which is a three-dimensional finite differential method to analyse the slope stability induced by goaf, The results indicated:the movement of surrounding rock had been being more intense, meanwhile the slope was instability,It might cause collapse and land slide of slope rock if no using filling method to treat timely.The sizeof plastic zone in slope rock reduced greatly after filling the goaf, that greatly improved slope stability. Results of simulation were in line with practical producing, validating that FLAC3D was an effective way of slope stability analysis induced by goaf.

Evaluation of the Steep Slope Stability Based on Theory of GPS Monitoring Analysis

Because of rock slope,surface Mine is full of danger. In this paper, the monitoring system configuration and data processing are discussed in combination with GPS monitoring and date analysis of slope deformation in an Iron Mine in order to seize the rule of rock deformation and provid a more reliable basis for taking measures for control the rock Stability.The dynamic monitoring system and rock Stability evaluation method are developed so as to resolved the rock Stability in the surface mine that would be underground mining.Which can also provide for the design plan、data processing 、technical measures of the control the rock Stability and promote the continuable development of the Surface Mine.

Study on high and steep slope stability of surface mine based on RFPA-SRM

The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows: the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.

Stability of Steep Slopes in Cemented Sands

The analysis of steep slope and cliff stability in variably cemented sands poses a significant practical challenge as routine analyses tend to underestimate the actually observed stability of existing slopes. The presented research evaluates how the degree of cementation controls the evolution of steep sand slopes and shows that the detailed slope geometry is important in determining the characteristics of the failure mode, which in turn, guide the selection of an appropriate stability analysis method. Detailed slope-profile cross sections derived from terrestrial lidar surveying of otherwise inaccessible cemented sand cliffs are used to investigate failure modes in weakly cemented [unconfined compressive strength (UCS)<30 kPa] and moderately cemented (30<UCS<400 kPa) sands and their role in the evolution of the geometry of the slopes. The results show that high-resolution slope topography, such as can be obtained with terrestrial lidar, is essential for identifying altogether different failure modes in weakly cemented (shear-mode) and moderately cemented (tensile-mode) sand slopes. Analyses show that the standard Culmann method for steep slopes is inappropriate for modeling the stability of cemented sand slopes since it tends to overpredict expected crest retreat and underestimate failure plane angle. Instead, a simplified analysis using infinite slope assumptions, but applied to a slope with finite dimensions subject to changing geometric conditions, such as toe erosion and slope steepening, is suggested for analysis of weakly cemented sand slopes. For moderately cemented sand slopes, a limit equilibrium analysis directly comparing the cliff tensile stress and cemented sand tensile strength is shown to reasonably predict failure conditions and timing as a result of either slope steepening or tensile strength loss, presumably from wetting in most cases.

Sensitivity analysis for parameters of a monitoring system for steep slopes of open-pit mines

Monitoring the stability of steep slopes of open-pit mines is a major issue relating to production safety in mines. In order to determine the technical parameters of a new type of supervising system applied in monitoring steep slopes of open-pit mines, the MSARMA method was used to establish analytical models for the monitoring system, given various parameter settings based on the description of mechanical monitoring principles. We used this sensitivity analysis to conclude that the setting of the most sensitive location of a mechanical monitoring system should be within a range of 1/5∼1/2 of the lower part in a vertical direction of steep slopes, with a rational and feasible range of the dip angle setting between 0°∼20°. Given the analytical results of our on-site experiments, we have shown that the parameters determined reflect the stability of steep slopes accurately and effectively. These conclusions provide a basis for the application of a new type of steep slope stability monitoring technology in open-pit mines.

The role of infiltration processes in steep slope stability of pyroclastic granular soils: laboratory and numerical investigation

Rainfall-induced landslides on steep slopes are a common feature in much of Italy’s mountain areas covered by shallow-pyroclastic deposits. Generally, these deposits are unsaturated and have a slope angle higher than 40°–50°; hence their stability is due to the positive effect of matric suction on soil shear strength. During rainfall, rainwater infiltration causes a decrease in suction, which in turn causes changes in soil mechanical and hydraulic properties, leading towards an instability process. However, the response of pyroclastic soil slopes to rainwater infiltration is not fully understood. The aim of this study is to link slope instability to the infiltration process on the basis of advanced geotechnical characterization, in situ monitoring and numerical analysis calibrated through a back-analysis of well-instrumented flume tests.

Geomechanical parameters of intact rocks and rock masses from the Canary Islands: Implications on their flank stability

New data on the geomechanical properties of the highly cohesive volcanic rocks of the Canary Archipelago and their role in the flank stability on oceanic islands are provided in this work. On the basis of the textural and petrological features, a preliminary classification of rocks, grouped into lithotypes, was carried out. This classification includes vesicular and non vesicular basalts, trachybasalts, trachytes, phonolites, welded and non welded ignimbrites. Strength and strain-related features are summarized here for each distinctive lithotype. Taking into account the results of the uniaxial and triaxial compressive tests, the geological strength index of rock masses and their textural–structural features, an estimate of the rock mass parameters and Mohr–Coulomb fit has been carried out. A final discussion on the impact of those geomechanical parameters as factors governing the stability of steep slopes in volcanic islands is then made here as a contribution in volcanic risk.

Wirkungen des Waldes auf oberflächennahe Rutschprozesse | Effects of forest on landslides

A very heavy thunderstorm in 1997 triggered a great number of shallow landslides near Sachseln in canton Obwalden. 280 of these were analysed in the field. The results show that, among other factors, the condition and structure of the forest considerably influence the stability of steep slopes.

Simplified Method for Evaluating Seismic Stability of Steep Slopes

Steep slopes composed of weakly cemented granular soils are common along the Pacific Coast of North America. These slopes, standing at angles of 30° to near vertical, are observed to be prone to seismically induced failures. The steep topography of these slopes makes them particularly susceptible to amplification of seismic waves, and the brittle nature of these materials make deformation-based stability analyses inappropriate. In this paper, a simplified method is presented for assessing the seismic stability of these slopes, utilizing average seismic coefficients to account for the effect of topography. This procedure is based on a review of field and laboratory observations, as well as analyses carried out using generalized consistent transmitting boundaries. The results of the analyses indicate that the amplification due to the soil column in the free field behind the crest dominates the response. The amplification due to topography, on the other hand, shows little variability, and is on the order of 50%. The proposed procedure presented herein gives practicing engineers a method to conduct stability analyses that better represents the actual field conditions for these steep, brittle slopes.