scholarly journals Repeat Glacier Collapses and Surges in the Amney Machen Mountain Range, Tibet, Possibly Triggered by a Developing Rock-Slope Instability

2019 ◽  
Vol 11 (6) ◽  
pp. 708 ◽  
Author(s):  
Frank Paul
Keyword(s):  
Satellite Data ◽  
Temperature Increase ◽  
Rock Slope ◽  
Slope Instability ◽  
Mountain Range ◽  
Rock Slopes ◽  
Direct Response ◽  
Hill Slope ◽  
Eastern Tibet ◽  
Regional Temperature

Collapsing valley glaciers leaving their bed to rush down a flat hill slope at the speed of a racing car are so far rare events. They have only been reported for the Kolkaglacier (Caucasus) in 2002 and the two glaciers in the Aru mountain range (Tibet) that failed in 2016. Both events have been studied in detail using satellite data and modeling to learn more about the reasons for and processes related to such events. This study reports about a series of so far undocumented glacier collapses that occurred in the Amney Machen mountain range (eastern Tibet) in 2004, 2007, and 2016. All three collapses were associated with a glacier surge, but from 1987 to 1995, the glacier surged without collapsing. The later surges and collapses were likely triggered by a progressing slope instability that released large amounts of ice and rock to the lower glacier tongue, distorting its dynamic stability. The surges and collapses might continue in the future as more ice and rock is available to fall on the glacier. It has been speculated that the development is a direct response to regional temperature increase that destabilized the surrounding hanging glaciers. However, the specific properties of the steep rock slopes and the glacier bed might also have played a role.

scholarly journals Assessment of Slope Instability and Risk Analysis of Road Cut Slopes in Lashotor Pass, Iran

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Mohammad Hossein Taherynia ◽  
Mojtaba Mohammadi ◽  
Rasoul Ajalloeian
Keyword(s):  
Rock Mass ◽  
Risk Analysis ◽  
Rock Slope ◽  
Classification Systems ◽  
Slope Instability ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
The Stability ◽  
Cut Slopes ◽  
Road Cut Slopes

Assessment of the stability of natural and artificial rock slopes is an important topic in the rock mechanics sciences. One of the most widely used methods for this purpose is the classification of the slope rock mass. In the recent decades, several rock slope classification systems are presented by many researchers. Each one of these rock mass classification systems uses different parameters and rating systems. These differences are due to the diversity of affecting parameters and the degree of influence on the rock slope stability. Another important point in rock slope stability is appraisal hazard and risk analysis. In the risk analysis, the degree of danger of rock slope instability is determined. The Lashotor pass is located in the Shiraz-Isfahan highway in Iran. Field surveys indicate that there are high potentialities of instability in the road cut slopes of the Lashotor pass. In the current paper, the stability of the rock slopes in the Lashotor pass is studied comprehensively with different classification methods. For risk analyses, we estimated dangerous area by use of the RocFall software. Furthermore, the dangers of falling rocks for the vehicles passing the Lashotor pass are estimated according to rockfall hazard rating system.

scholarly journals Stability assessment of degrading permafrost rock slopes based on a coupled thermo-mechanical model

2020 ◽  
Author(s):  
Philipp Mamot ◽  
Samuel Weber ◽  
Saskia Eppinger, ◽  
Michael Krautblatter
Keyword(s):  
Slope Stability ◽  
Rock Slope ◽  
Fracture Network ◽  
Slope Instability ◽  
Rock Slope Stability ◽  
Permafrost Degradation ◽  
Rock Slopes ◽  
High Mountains ◽  
Permafrost Rock ◽  
Wide Range

Abstract. In the last two decades, permafrost degradation has been observed to be a major driver of enhanced rock slope instability and associated hazards in high mountains. While the thermal regime of permafrost degradation in high mountains has already been intensively investigated, the mechanical consequences on rock slope stability have so far not been reproduced in numerical models. Laboratory studies and conceptual models argue that warming and thawing decrease rock and discontinuity strength and promote deformation. This study presents the first general approach for a temperature-dependent numerical stability model that simulates the mechanical response of a warming and thawing permafrost rock slope. The proposed procedure is applied to a rockslide at the permafrost-affected Zugspitze summit crest. Laboratory tests on frozen and unfrozen rock joint and intact rock properties provide material parameters for the discontinuum model developed with the Universal Distinct Element Code (UDEC). Geophysical and geotechnical field surveys deliver information on the permafrost distribution and fracture network. The model demonstrates that warming decreases rock slope stability to a critical level, while thawing initiates failure. A sensitivity analysis of the model with a simplified geometry and warming trajectory below 0 °C shows that progressive warming close to the melting point initiates instability above a critical slope angle of 50–62°, depending on the orientation of the fracture network. The increase in displacements intensifies for warming steps closer to zero degree. The simplified and generalised model can be applied to permafrost rock slopes (i) which warm above −4 °C, (ii), with ice-filled joints, (iii) with fractured limestone or probably most of the rock types relevant for permafrost rock slope failure, (iv) with a wide range of slope angles (30–70°) and orientations of the fracture network (consisting of three joint sets). The presented model is the first one capable of assessing the future destabilisation of degrading permafrost rock slopes.

scholarly journals A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes

2021 ◽  
Vol 9 (5) ◽  
pp. 1125-1151
Author(s):  
Philipp Mamot ◽  
Samuel Weber ◽  
Saskia Eppinger ◽  
Michael Krautblatter
Keyword(s):  
Rock Slope ◽  
Slope Angle ◽  
Fracture Network ◽  
Slope Instability ◽  
Permafrost Degradation ◽  
Rock Slopes ◽  
High Mountains ◽  
Temperature Dependent ◽  
Permafrost Rock ◽  
Wide Range

Abstract. Over the last 2 decades, permafrost degradation has been observed to be a major driver of enhanced rock slope instability and associated hazards in high mountains. While the thermal regime of permafrost degradation in high mountains has been addressed in several modelling approaches, no mechanical models that thoroughly explain rock slope destabilisation controls in degrading permafrost have been developed. Meanwhile, recent laboratory studies have shown that degrading permafrost affects both, rock and ice mechanical strength parameters as well as the strength of rock–ice interfaces. This study presents a first general approach for a temperature-dependent numerical stability model that simulates the mechanical response of a warming and thawing permafrost rock slope. The proposed procedure is exemplified using a rockslide at the permafrost-affected Zugspitze summit crest. Laboratory tests on frozen and unfrozen rock joint and intact rock properties provide material parameters for discontinuum models developed with the Universal Distinct Element Code (UDEC). Geophysical and geotechnical field surveys reveal information on permafrost distribution and the fracture network. This model can demonstrate how warming decreases rock slope stability to a critical level and why thawing initiates failure. A generalised sensitivity analysis of the model with a simplified geometry and warming trajectory below 0 ∘C shows that progressive warming close to the melting point initiates instability above a critical slope angle of 50–62∘, depending on the orientation of the fracture network. The increase in displacements intensifies for warming steps closer to 0 ∘C. The simplified and generalised model can be applied to permafrost rock slopes (i) which warm above −4 ∘C, (ii) with ice-filled joints, (iii) with fractured limestone or probably most of the rock types relevant for permafrost rock slope failure, and (iv) with a wide range of slope angles (30–70∘) and orientations of the fracture network (consisting of three joint sets). Here, we present a benchmark model capable of assessing the future destabilisation of degrading permafrost rock slopes.

Influences of Joint Persistence and Groundwater on Wedge Failure Potential of Jointed Rock Slope

2020 ◽  
Author(s):  
Yu-Hsuan Chang ◽  
Cheng-Han Lin ◽  
Ming-Lang Lin
Keyword(s):  
Rock Slope ◽  
Water Pressure ◽  
Jointed Rock ◽  
Slope Instability ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Wedge Failure ◽  
Large Landslide ◽  
Potential Failure ◽  
The Stability

<p>Joint persistence and groundwater are critical factors that influence the stability of rock slope. Persistence dominates the extent of pre-existing potential failure surfaces. Under certain conditions, slope instability may vary with time, as the propagation of existing joints leads to the development of fully persistence failure surfaces. At the same time, groundwater may travel through the fracture network and provides an external force to unstable rock masses, resulting in the damage of rock slope failure hard to predict. In general, when a rock slope consists of two or more sets of joints, the wedge failure often becomes the initial structurally controlled failure of a progressive large landslide. A classic case, which was occurred at a steep cut rock slope on 32.5k, Provincial Highway 7, Taiwan, had been completely recorded with UAV-surveys, field investigations and witness. The landslide first occurred on 13th May 2019 as a wedge failure with the magnitude of the volume of 892 m<sup>3</sup> and resulted in a large landslide on 29th July 2019 with the magnitude of the volume of 37234 m<sup>3</sup>, destroyed the protection measures and roads. According to the field investigation, groundwater was discovered flowing out from the line of intersection of persistence joints, which could be the main reason leads to the wedge failure and the progressive large rockslide. Hence, the couple mechanics-hydraulic behavior in a rock slope should be studied in more detail to mitigate such hazards.</p><p>In this study, sandbox model was applied to clarify the effects of the groundwater and joint friction on failures of single rock wedge. In addition, the software 3DEC, which is based on Distinct Element method, was carried out to extent the analysis conditions. The results of sandbox simulations were used to calibrate the performance of the numerical model, especially the coupled hydro-mechanical analysis. The stability of jointed rock slopes under different persistence and various water pressure conditions has been studied. It is believed that the study can enhance the way for stability analysis and monitoring of the potential failure of jointed rock slopes.</p><p>Keywords: Wedge failure; Joint persistence; Groundwater; Rock slope stability.</p><p> </p>

scholarly journals Rock Slope Stability Assessment Along Rawanduz Main Road, Kurdistan Region

2021 ◽  
Vol 54 (1B) ◽  
pp. 79-93
Author(s):  
Rebaz Qader
Keyword(s):  
Rock Slope ◽  
Slope Instability ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Kurdistan Region ◽  
Main Road ◽  
The Road ◽  
Wedge Sliding ◽  
Major Factors ◽  
Type Of Failure

The rock slope instability along the Khalifan-Bekhal-Rawanduz main road has been studied in the southwestern limb of the Bradost anticline (Mountain) and both northeastern and southwestern limb of the Korek anticline (Mountain) in the northeast of the Erbil city, Kurdistan Region, Iraq. The major factors of the instability of the rock slopes in the study area are types of discontinuous and the degree of erosion. Ten stations have been chosen for fieldwork. The expected failure types that may occur along the road are plane sliding and wedge sliding. This research is mainly focused on the type of failure along the rock slope and the factor that affect the instability of the studied slopes and have found that they are slope orientation and geometry of the discontinuity. Different remediation methods are proposed for the studied rock slopes base on rock slope analysis. The rock slopes along the road require continuous monitoring because of their hazard conditions.

An algorithm for the 3D ROck Slope Kinematic Analysis (ROKA) based on RPAS digital photogrammetry data.

2021 ◽  
Author(s):  
Niccolò Menegoni ◽  
Daniele Giordan ◽  
Cesare Perotti
Keyword(s):  
Kinematic Analysis ◽  
Rock Slope ◽  
Traditional Approach ◽  
Rock Slopes ◽  
Digital Photogrammetry ◽  
Modes Of Failure ◽  
Wedge Sliding ◽  
Flexural Toppling ◽  
The Stability ◽  
Digital Outcrop

<p>Among the several adopted methods for the kinematic analysis of the possible modes of failure that could affect a rock slope, the Markland test is the most used. Whereas, it has the advantage of being simple and fast, it has some limits, as the impossibility to manually consider the several different slope orientations and their interaction with the discontinuity dimensions and positions.</p><p>Recently, the improvements in the Remote Piloted Aerial System (RPAS) digital photogrammetry techniques for the development and mapping of Digital Outcrop Models (DOMs) have given the possibility of developing new automatized digital approaches. In this study, ROKA (ROck slope Kinematic Analysis) algorithm is presented. It is an open-source algorithm, written in MATLAB language, which aims to perform the kinematic analysis of the stability of a rock slope using the discontinuity measurements collected onto 3D DOMs. Its main advantage is the possibility to identify the possible critical combination between the 3D georeferenced discontinuities and the local surface of the slope. In particular, the critical combinations that can activate the planar sliding, flexural toppling, wedge sliding and direct toppling modes of failures can be detected and highlighted directly on the DOM. Hence, the ROKA algorithm can make the traditional approach for the kinematic analysis of a rock slope more effective, allowing not only to simplify the analysis, but also to increase its detail. This can be very important, in particular, for the analysis of large and complex rock slopes.</p>

scholarly journals Identification of active release planes using ground-based differential InSAR at the Randa rock slope instability, Switzerland

2009 ◽  
Vol 9 (6) ◽  
pp. 2027-2038 ◽  
Author(s):  
V. Gischig ◽  
S. Loew ◽  
A. Kos ◽  
J. R. Moore ◽  
H. Raetzo ◽  
...  
Keyword(s):  
Rock Slope ◽  
Hazard Analysis ◽  
Failure Surface ◽  
Accurate Estimate ◽  
Slope Instability ◽  
Lateral Release ◽  
Rupture Plane ◽  
Local Movement ◽  
Active Release ◽  
Displacement Patterns

Abstract. Five ground-based differential interferometric synthetic aperture radar (GB-DInSAR) surveys were conducted between 2005 and 2007 at the rock slope instability at Randa, Switzerland. Resultant displacement maps revealed, for the first time, the presence of an active basal rupture zone and a lateral release surface daylighting on the exposed 1991 failure scarp. Structures correlated with the boundaries of interferometric displacement domains were confirmed using a helicopter-based LiDAR DTM and oblique aerial photography. Former investigations at the site failed to conclusively detect these active release surfaces essential for kinematic and hazard analysis of the instability, although their existence had been hypothesized. The determination of the basal and lateral release planes also allowed a more accurate estimate of the currently unstable volume of 5.7±1.5 million m3. The displacement patterns reveal that two different kinematic behaviors dominate the instability, i.e. toppling above 2200 m and translational failure below. In the toppling part of the instability the areas with the highest GB-DInSAR displacements correspond to areas of enhanced micro-seismic activity. The observation of only few strongly active discontinuities daylighting on the 1991 failure surface points to a rather uniform movement in the lower portion of the instability, while most of the slip occurs along the basal rupture plane. Comparison of GB-DInSAR displacements with mapped discontinuities revealed correlations between displacement patterns and active structures, although spatial offsets occur as a result of the effective resolution of GB-DInSAR. Similarly, comparisons with measurements from total station surveys generally showed good agreement. Discrepancies arose in several cases due to local movement of blocks, the size of which could not be resolved using GB-DInSAR.

scholarly journals An integrated approach to investigate climate-driven rockfall occurrence in high alpine slopes: the Bessanese glacial basin, Western Italian Alps

2020 ◽  
Vol 17 (11) ◽  
pp. 2591-2610
Author(s):  
Cristina Viani ◽  
Marta Chiarle ◽  
Roberta Paranunzio ◽  
Andrea Merlone ◽  
Chiara Musacchio ◽  
...  
Keyword(s):  
Climate Change ◽  
Active Layer ◽  
Integrated Approach ◽  
Slope Instability ◽  
High Mountain ◽  
Positive Temperature ◽  
Rock Slopes ◽  
Italian Alps ◽  
Near Surface ◽  
Basin Scale

Abstract Rockfalls are one of the most common instability processes in high mountains. They represent a relevant issue, both for the risks they represent for (infra) structures and frequentation, and for their potential role as terrestrial indicators of climate change. This study aims to contribute to the growing topic of the relationship between climate change and slope instability at the basin scale. The selected study area is the Bessanese glacial basin (Western Italian Alps) which, since 2016, has been specifically equipped, monitored and investigated for this purpose. In order to provide a broader context for the interpretation of the recent rockfall events and associated climate conditions, a cross-temporal and integrated approach has been adopted. For this purpose, geomorphological investigations (last 100 years), local climate (last 30 years) and near-surface rock/air temperatures analyses, have been carried out. First research outcomes show that rockfalls occurred in two different geomorphological positions: on rock slopes in permafrost condition, facing from NW to NE and/or along the glacier margins, on rock slopes uncovered by the ice in the last decades. Seasonal thaw of the active layer and/or glacier debutressing can be deemed responsible for slope failure preparation. With regard to timing, almost all dated rock falls occurred in summer. For the July events, initiation may have been caused by a combination of rapid snow melt and enhanced seasonal thaw of the active layer due to anomalous high temperatures, and rainfall. August events are, instead, associated with a significant positive temperature anomaly on the quarterly scale, and they can be ascribed to the rapid and/or in depth thaw of the permafrost active layer. According to our findings, we can expect that in the Bessanese glacierized basin, as in similar high mountain areas, climate change will cause an increase of slope instability in the future. To fasten knowledge deepening, we highlight the need for a growth of a network of high elevation experimental sites at the basin scale, and the definition of shared methodological and measurement standards, that would allow a more rapid and effective comparison of data.

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