Transient seepage and slope stability analysis for rainfall induced landslide: a case study

A transient seepage and slope stability analyses were carried out for a case of rainfall-induced landslide in Air Laya Indonesia . The landslide occurred in December 2002 on a dumping area of an open coal mining site. This study examined the mechanism causing the slope failure based on transient analysis between April 21, 2001 and December 1, 2002. The slope profile was simulated using a seepage analyzing tool, VADOSE/W and the soil properties were determined based on field and laboratory data. The saturation profile resulted from seepage analysis was exported to SLOPE/W for the slope stability evaluation. The results show that the main factor contributing to the landslide is the reduction of shear strength due to increase in soil moisture content impelled by the formation of tension cracks on the ground surface of the slope

Development of Landslide Warning System

Landslides cause approximately 25 to 50 deaths and US$1 - 2 billion worth of damage in the United States annually. They can be triggered by humans or by nature. It has been widely recognized that rainfall is one of the major causes of slope instability and failure. Slope remediation and stabilization efforts can be costly. An early warning system is a suitable alternative and can save human lives. In this project, an early warning system was developed for a 40-foot-high cut slope on the island of Hawaii. To achieve the objective, subsurface investigations were performed and undisturbed samples were collected. For the purpose of unsaturated soil testing, new testing apparatuses were developed by modifying the conventional oedometer and direct shear cells. The unsaturated soil was characterized using two separate approaches and, later, the results were discussed and compared. The slope site was instrumented for the measurement of suction, water content, displacement, and precipitation. The collected climatic data along with the calibrated hydraulic parameters were used to build an infiltration-evapotranspiration numerical model. The model estimations were compared with the field measurements and showed good agreement. The verified model was used to determine the pore-water pressure distribution during and after a 500-years return storm. Later, the pore-water pressure distribution was transferred to a slope stability software and used to study the slope stability during and after the storm. Based on a 2D slope stability analysis, the slope can survive the 500-year storm with a factor of safety of 1.20. Instrument threshold values were established for water content sensors and tensiometers using a traffic-light-based trigger criterion

Study on the weight coefficient influence of surface water on the stability of open-pit dump. Comparative analysis of 6 degree seismic simulation

Taking Baorixile open-pit coal mine as an example, the regional hydrogeological conditions and the mining area hydrogeological conditions are briefly introduced. Analyzing the factors influencing the stability of open pit dump, discussing the classification and proportion of influencing factors, the numerical simulation of the influence of surface water and seismic vibrations on the stability of open-pit dump is carried out. Results show: Surface water is an important factor affecting the stability of open-pit dump, extremely sensitive to the safety factor, the influence of slope instability is similar to that of intensity 6 earthquake. The weight coefficient of surface water to slope stability is in the range of 0.4 to 0.9

Susceptibility mapping of shallow landslides inducing debris flows: a comparison of physics-based approaches

The assessment of timing and potential locations of rainfallinduced shallow landslides through mathematical models represents a challenge for the assessment of landslide hazard, especially in cases with limited or not available data. In fact, modeling slope hydrological response and stability requires accurate estimates of unsaturated/saturated hydraulic and geotechnical properties of materials involved in landsliding, as well as climate and topography. Such aspect is relevant for the prediction of location and timing of landslide events, which is greatly needed to reduce their catastrophic effects in terms of economic losses and casualties. To such a scope, we present the comparison of results of two physics-based models applied to the assessment of susceptibility to shallow rainfall-induced landslides in Valtellina region (northern Italy). The analyses were carried out considering effects of availability, resolution and type of data concerning spatial distribution, thickness and properties of soils coverings. For such a scope, the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) and the Climatic Rainfall Hydrogeological Modeling Experiment (CHRyME) models were considered. The study emphasizes issues in performing distributed numerical slope stability modeling depending on the availability of spatially distributed soil properties which hamper the quality of physic-based models. Further analyses aimed at the probabilistic assessment of landslide spatial distribution, related to a specific value of rainfall threshold, can be considered as potentially applicable to multi-scale landslide hazard mapping and extendable to other similar mountainous frameworks

SUSCEPTIBILITY MAPPING OF SHALLOW LANDSLIDES INDUCING DEBRIS FLOWS: A COMPARISON OF PHYSICS-BASED APPROACHES

The assessment of timing and potential locations of rainfallinduced shallow landslides through mathematical models represents a challenge for the assessment of landslide hazard, especially in cases with limited or not available data. In fact, modeling slope hydrological response and stability requires accurate estimates of unsaturated/saturated hydraulic and geotechnical properties of materials involved in landsliding, as well as climate and topography. Such aspect is relevant for the prediction of location and timing of landslide events, which is greatly needed to reduce their catastrophic effects in terms of economic losses and casualties. To such a scope, we present the comparison of results of two physics-based models applied to the assessment of susceptibility to shallow rainfall-induced landslides in Valtellina region (northern Italy). The analyses were carried out considering effects of availability, resolution and type of data concerning spatial distribution, thickness and properties of soils coverings. For such a scope, the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) and the Climatic Rainfall Hydrogeological Modeling Experiment (CHRyME) models were considered. The study emphasizes issues in performing distributed numerical slope stability modeling depending on the availability of spatially distributed soil properties which hamper the quality of physic-based models. Further analyses aimed at the probabilistic assessment of landslide spatial distribution, related to a specific value of rainfall threshold, can be considered as potentially applicable to multi-scale landslide hazard mapping and extendable to other similar mountainous frameworks

Physically based estimation of rainfall thresholds triggering shallow landslides in volcanic slopes of Southern Italy

On the 4th and 5th of March 2005, about 100 rainfall-induced landslides occurred along volcanic slopes of Camaldoli Hill in Naples, Italy. These started as soil slips in the upper substratum of incoherent and welded volcaniclastic deposits, then evolved downslope according to debris avalanche and debris flow mechanisms. This specific case of slope instability on complex volcaniclastic deposits remains poorly characterized and understood, although similar shallow landsliding phenomena have largely been studied in other peri-volcanic areas of the Campania region underlain by carbonate bedrock. Considering the landslide hazard in this urbanized area, this study focused on quantitatively advancing the understanding of the predisposing factors and hydrological conditions contributing to the initial landslide triggering. Borehole drilling, trial pits, dynamic penetrometer tests, topographic surveys, and infiltration tests were conducted on a slope sector of Camaldoli Hill to develop a geological framework model. Undisturbed soil samples were collected for laboratory testing to further characterize hydraulic and geotechnical properties of the soil units identified. In situ soil pressure head monitoring probes were also installed. A numerical model of two-dimensional variably saturated subsurface water flow was parameterized for the monitored hillslope using field and laboratory data. Based on the observed soil pressure head dynamics, the model was calibrated by adjusting the evapotranspiration parameters. This physically based hydrologic model was combined with an infinite-slope stability analysis to reconstruct the critical unsaturated/saturated conditions leading to slope failure. This coupled hydromechanical numerical model was then used to determine intensity–duration (I-D) thresholds for landslide initiation over a range of plausible rainfall intensities and topographic slope angles for the region. The proposed approach can be conceived as a practicable method for defining a warning criterion in urbanized areas threatened by rainfall-induced shallow landslides, given the unavailability of a consistent inventory of past landslide events that prevents a rigorous empirical analysis

A first step towards a IoT-based local early warning system for an unsaturated slope in Norway

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DEVELOPMENT OF A DECISION-MAKING TOOL FOR PREDICTION OF RAINFALL-INDUCED LANDSLIDES

Landslides are frequently observed in mountainous places following prolonged periods of rain, frequently resulting in substantial topography changes. They pose a significant risk to human lives and the built environment globally, particularly in areas prone to excessive rainfall. While slope failures can occur because of human-caused factors such as slope loading or toe cutting for construction purposes, many failures occur because of rainfall penetrating an otherwise stable slope. A greater understanding of the characteristics and mechanics of landslides is consequently critical for geotechnical research, particularly in evaluating prospective mitigation strategies. The potential of slope failure is a primary consideration when assessing the risk associated with landslide movement. The current research seeks to develop a real-time decision-making tool for rainfall-induced landslides that enables users to compare governing parameters during intense rainfall, comprehend the in-situ stability condition, and therefore assure safety. The first section of the study employs a one-dimensional transient infiltration analytical solution (Yuan and Lu 2005) to evaluate seasonal variations in soil hydrologic behavior. The one-dimensional transient infiltration analytical solution enables better control and flexibility of the soil-water characteristic curve’s transient infiltration equations and fitting parameters. Due to the model\u27s ability to determine fitting parameters, it was possible to calibrate it using in-situ soil hydrologic behavior. The second section of the study will examine how a slope behaves under seasonal rainfall variation utilizing soil hydrologic and mechanical techniques. The case study is based on data collected from a true monitored slope. Two years of monitoring were conducted on the slope. Throughout this time, the place experienced seasonal drying and wetting. Field hydrologic and deformation sensors were installed during the monitoring period. A finite element program was used to generate the monitored slope utilizing in situ slope geometry and initial condition data. Following that, the hydrologic and deformation reactions of the soil were investigated. At two previously reported slope locations, behavioral analysis is conducted. The final section of the study proposes a model for projecting the sub-surface’s volumetric water content using observations of surface rainfall and evapotranspiration. Initially, the prediction model was created using the location of a previously reported site. The prediction model was validated and then tested in six distinct Kentucky locations. The six locations lacked in-situ measurements of soil hydrologic and geotechnical parameters. As a result, Soil Active and Passive Moisture (SMAP) and Web Soil Survey were used to collect soil hydrologic and geotechnical data for the test locations. Combining the data with SMAP\u27s soil hydrology data resulted in the establishment of a safety factor for the test sites. On increasing competitive advantage for member firms. Firm-level outcomes and inter-organizational relationship structures related to network involvement were investigated