Changes In Stability Conditions Research Articles

Landslide susceptibility mapping for the Red Sea Mountains: A multi-criteria decision analysis approach

The Earth's climate system is clearly warming. Unquestionably, climate change has an impact on landslides by affecting the stability of both naturally occurring and artificially constructed slopes. Less certain are the type, extent, degree, and direction of the changes in stability conditions as well as the location, abundance, activity, and frequency of landslides in response to the expected climate changes. Climate change threatens global ecosystems, causing severe human and economic losses through sea level rise, hurricanes, flooding, landslides, and heat waves. Landslides in high mountains could become more common as a result of these changes. The high-speed electric train project in Egypt seeks to provide sustainable transportation, lessen climate change, and enhance public health. The study area was conducted along a 70-km track in the Eastern Desert, Egypt, across steep and rugged basement rocks of the Red Sea mountain chain (RSM). The geographic pinpointing of landslide susceptibility zones plays a significant role in promoting hazards mitigation in mountainous areas, such as RSM. The aim of this research project is to create a landslide susceptibility map (LSM) utilizing multi-criteria decision analysis (MCDA) in the region using information value (IV) and analytical hierarchy process (AHP) approaches that encompass the third proposed track of the high-speed electric railroad Qena-Hurghada between the RSM. The landslide inventory map, which has a total of 12 single landslide locations, was created based on fieldwork using hand-held GPS and Landsat 8 images. The two decision-making techniques were used to contrast the LSM factors based on the knowledge of experts using the qualitative method of AHP with the statistical approach that depends on the field data IV. Ten landslide-influencing parameters taken into consideration are slope, lithology, rainfall distribution, distance to fault, distance to track, seismicity of area, distance to epicenter, land cover, distance to stream, and aspect. The parameters were obtained using LANDSAT8 and SRTM DEM of a 30 m resolution, vectorized lithological structure units from a 1:2000, 000 map, and data between (1913–2000) for yearly precipitation and (1997–2018) for seismic activity of the research area. A GIS-based method produces a themed layer map for each geoenvironmental element, weighing each parameter after examination. A LSM was produced using a combination of thematic layers that were then separated into four grades: low, moderate, high, and very high, based on the intensity of the landslide vulnerability. According to AUC data, the IV model has a better success rate 0.85 than the AHP model 0.82. The study's models, especially when applied to the IV method, showed good accuracy in forecasting landslide vulnerability. The method shows rising landslide percentages with susceptibility and delivers accurate results that are compatible with the landslide inventory map. Environmental decisions often lead to unintended consequences due to lost information, incorrect factor selection, limited expert expertise, and ignoring uncertainty. This investigation emphasizes the importance of LSM as a tool for decision-makers to minimize landslide losses and damage.

Changes in stability conditions of clay slopes due to leaching: a case study

Leaching through natural soil deposits manifests in form of modifications in mechanical parameters of the host soil. One of the outcomes of strength reduction in soils due to leaching is slope instability which is exhibited in the form of sliding. In this study, a series of chemical, physical and mechanical tests have been carried out to investigate the effect of leaching on the stability of a clay slope in north of Iran. Results show that leaching removes the soluble salts from the soil, leaving porous and unstable structure. Leaching causes reduction of the mechanical properties of the host soil including deformation and shear strength parameters in drained and undrained conditions. Results of the laboratory tests revealed that leaching has given rise to more than 30% reduction in the plasticity index, 10% decrease in the dry unit weight and 45% decline of the unconfined compressive strength of the host soil. The leaching-induced diminution of the mechanical performance of the host soil is geared to have some slope instability implications by exhibiting a maximum of 50% reduction in the slop stability safety factor.

Nonlinear Dynamics of Structures with Material Degradation

Structures usually experience deterioration during their working life. Oxidation, corrosion, UV exposure, and thermo-mechanical fatigue are some of the most well-known mechanisms that cause degradation. The phenomenon gradually changes structural properties and dynamic behaviour over their lifetime, and can be more problematic and challenging in the presence of nonlinearity. In this paper, we study how the dynamic behaviour of a nonlinear system changes as the thermal environment causes certain parameters to vary. To this end, a nonlinear lumped mass modal model is considered and defined under harmonic external force. Temperature dependent material functions, formulated from empirical test data, are added into the model. Using these functions, bifurcation parameters are defined and the corresponding nonlinear responses are observed by numerical continuation. A comparison between the results gives a preliminary insight into how temperature induced properties affects the dynamic response and highlights changes in stability conditions of the structure.

Impact of meteorological conditions on stability of selected slopes in the Wiśnicz Foothills

Abstract Impact of meteorological conditions on stability of selected slopes in the Wiśnicz Foothills. Mass wasting is one of the most important processes influencing the shaping of mountain slopes. Most programs for testing mass wasting are limited to short-time, single observations, and to surface measurements of the big phenomenon ignoring shallow landslides occur resulting in slope covers, or on its border with the rock solid. That is why, when analyzing the causes of mass wasting processes, it is extremely important to assess the influence of meteorological conditions on water circulation in the landslide slope system and the status of stresses in a soil medium that is connected with it. The aim of this work was to determine the course of changes in stability conditions for two selected slopes, connected with meteorological conditions in the period of 2009-2013 on the area of the Wiśnicz Foothills. Numerical analysis were subjected to two slopes in villages the Królówka and the Łychów. Meteorological data for analysis, i.e. air temperature and soil humidity, wind speed, precipitation sum and length, were taken from the station Jagiellonian University in Łazy. To determine the course of changes of stability factor used capabilities Geostudio 2007 (Slope/W, Vadose/W, Seep/W). The work is a pre-development servant indicate the formation of shallow landslides present in silt. Results of the stability calculations confirmed the common opinions that conditions of slope balance are very strongly connected with atmospheric precipitation, but it was also shown that they also depend significantly on thermal conditions. These calculations showed that in the period 2009-2013 the most unfavorable conditions of stability were obtained in May 2010, which is a confirmation of the situation observed in reality.

Projected regional-scale changes in atmospheric stability condition for the development of summertime convective precipitation in the Tokyo metropolitan area under global warming

This study examined regional-scale changes in stability conditions for the occurrence of summertime convective precipitation under global warming projected by global climate simulations. Precipitation events over the Kanto Plain on synoptically undisturbed days were specifically focused on. The outputs of the 20-km-resolution global model simulations for the present and a future warming climate were used for the analyses. It was shown that temperature and moisture content throughout the troposphere are projected to increase more in the rainy cases than in the August mean cases from the present climate to the future and that the moisture increase below the 700-hPa level is significantly enhanced. The effects of future warming result in the moisture increase favorably at the lower levels. Owing to the low-level moisture increase, some stability indices indicate a destabilizing tendency with a statistical significance. From the projected changes in the stability condition for precipitation occurrence, it is implied that the precipitation amount is considered to increase if a cumulonimbus cloud and its organized systems once develop. The degree of the destabilization of precipitation environments is projected to increase more significantly than that of non-precipitation environments, and therefore, the precipitation will be more intensified in a future climate.

Modelling probability of rainfall-induced shallow landslides in a changing climate, Otta, Central Norway

We analyse slope stability conditions for shallow landslides under an extreme precipitation regime with regard to present and future scenarios, in order to first study the effect of changes in precipitation on stability conditions, considering uncertainty in the model parameters, and second to evaluate which factors contribute the most to model output and uncertainty. We used a coupled hydrological-stability model to study the hydrological control on shallow landslides in different precipitation regimes, with reference to the case study of Otta, located in central east Norway. We included a wide range of climatic settings, taking intensity, duration of the extreme events and two different antecedent precipitation conditions into account. Eleven future scenarios were determined using results of down-scaled meteorological models. Considering the uncertainty in the soil parameters, we used the Monte Carlo approach and probability of failure resulting from 5,000 trials was calculated for each precipitation scenario. In unstable areas the probabilities of failure at present and future conditions were compared using a bootstrapping method. Sensitivity analysis was carried out to understand how variations in input parameters influence the output of the selected model. The results show changes in the modelled stability conditions only if the effect of antecedent precipitation is not taken into account. The uncertainties in the predicted extreme precipitation events, soil parameters, and antecedent precipitation conditions do not allow any accurate estimation of changes in stability conditions for shallow landslides.

The effects of atmospheric stability on coastal wind climates

A theoretical model of flow over a change in surface roughness shows that given an average geostrophic wind of between 8 and 13 m s−1 and near-neutral conditions the difference in equilibrium wind speed at 50 m height over roughness of 0.1 m and over the sea surface is about 20% or 2 m s−1. However, in non-neutral conditions the difference between on- and off-shore wind speeds is affected by changes in stability conditions. Using data from an off-shore monitoring project it is shown that flow over sea is typically associated with smaller stability corrections to the logarithmic wind speed profile owing to an increase in the number of near-neutral and unstable observations compared to flow over land. The presence of land is still detectable after flow of 1–2 km off-shore but its effect on stability and therefore the wind speed profile is reduced. The differences between stability climates on- and off-shore are not simple to elucidate since a number of factors such as the orientation of the coastline with regard to the prevailing wind direction, water depth and latitude are probably also important. Copyright © 1999 Royal Meteorological Society

Slope instability and valley formation in Canadian soft clay deposits

The purposes of the paper are to examine the deepening of valleys in clay deposits of Eastern Canada and in particular to look at the changes in the groundwater regime and slope stability conditions during valley formation. Field observations and laboratory testing indicate that the rate of valley deepening in Champlain clay deposits is of the order of only a few millimetres a year, owing to the low erodibility of the intact clay. The clay banks are, however, more erodible, owing to alteration and fissuration.The stratigraphy of Eastern Canadian clay deposits can be simplified by considering it to be a stratum of low permeabilityconfined between two boundary layers of relatively high permeability, which are the till layer at the base and a weathered crust or coarse-grained layer at the top. As the valley bottom get closer to the bottom till layer, the groundwater regime, and consequently the stability conditions, are modified. During the process of valley formation, the groundwater regime passes through astage where the conditions are rather detrimental to slope stability as it evolves toward conditions that enhance bank stability. Those changes in stability conditions happen over geological time more rapidly or less, depending on clay erodibility. Key words: soft clay, valley formation, slope stability, groundwater, erosion, erodibility.