Thermomechanical forcing of deep rock slope deformation: 2. The Randa rock slope instability

2011 ◽  
Vol 116 (F4) ◽  
Author(s):  
Valentin S. Gischig ◽  
Jeffrey R. Moore ◽  
Keith F. Evans ◽  
Florian Amann ◽  
Simon Loew
Keyword(s):  
Rock Slope ◽  
Slope Deformation ◽  
Slope Instability ◽  
Deep Rock

scholarly journals Thermomechanical forcing of deep rock slope deformation: 1. Conceptual study of a simplified slope

2011 ◽  
Vol 116 (F4) ◽  
Author(s):  
Valentin S. Gischig ◽  
Jeffrey R. Moore ◽  
Keith F. Evans ◽  
Florian Amann ◽  
Simon Loew
Keyword(s):  
Rock Slope ◽  
Slope Deformation ◽  
Deep Rock ◽  
Conceptual Study

scholarly journals Unraveling spatial and temporal heterogeneities of very slow rock-slope deformations with targeted DInSAR analyses

2021 ◽  
Author(s):  
Federico Franzosi ◽  
Chiara Crippa ◽  
Mattia Zonca ◽  
Andrea Manconi ◽  
Giovanni B. Crosta ◽  
...  
Keyword(s):  
Rock Slope ◽  
Regional Scale ◽  
Temporal Trends ◽  
Structural Data ◽  
Local Scale ◽  
Slope Deformation ◽  
Slope Instability ◽  
Gps Data ◽  
Multi Temporal

<p>Spaceborne radar interferometry is a powerful tool to characterize landslide activity. However, its application to very slow rock slope deformations (displacement rates < 5 cm/yr) in alpine environments remains challenging due to low signal-to-noise ratio, severe atmospheric and snow cover effects, and heterogeneous deformation patterns related to complex landslide mechanisms in space and time.</p><p>In this study we combine available SqueeSAR<sup>TM</sup> data (Sentinel 1A/B ascending and descending, 2015-2017), ad hoc multi-temporal baseline DInSAR processing (2016-2019), GPS data (2015 to 2019) and detailed field mapping to unravel the kinematics, internal segmentation and style of activity of the Mt. Mater deep-seated gravitational slope deformation (DSGSD) in Valle Spluga (Italy). The high relief slope (1500-3000 m.a.s.l.) is made of dominant micaschist and paragneiss of the Stella-Timun complex (Suretta nappe) and ranges in inclination between 33° (< 2500 m a.s.l.) and 25° (> 2500 m a.s.l.). At 2900 m a.s.l. the slope is cut by a sharp triangular headscarp with a vertical downthrow of about 40 m, moving downslope, shallower arcuate scarps mark the transition to two nested large landslides, affecting the slope between 2400 m a.s.l. and 1550 m a.s.l; with highly deformed toes.</p><p>Through 2DInSAR decomposition, we highlight the global translational kinematics of the DSGSD. However, regional scale processed PSI data result unsuitable to capture the spatial complexity of the phenomenon at the local scale. To obtain a spatially-distributed characterization of the DSGSD displacement patterns, we process several multi-temporal interferograms and retrieve unwrapped phase and displacement maps according to a process-oriented, targeted approach based on variable temporal baselines (from 24-days to 1-year). In this context: a) 1-year interferograms provide a picture of long-term background DSGSD displacement signals; b) seasonal interferograms highlight displacement trends suggesting a complex response of different slope sectors to hydrological input; c) 24 days interferograms outline a triangular shaped active sector extending between 2500 m a.s.l. and the main DSGSD headscarp, corresponding to the movement of extensive debris cover and overlying periglacial features.</p><p>Our analyses clearly outline a composite slope instability and a strong spatial heterogeneity with different nested sectors possibly undergoing different evolutionary trends towards failure. The combined analysis of seasonal interferograms and GPS data further confirm a sensitivity of the different slope sectors to hydrological forcing modulated by snowmelt and rainfalls. The herein results outline the potential of a targeted use of DInSAR, carefully constrained by field geological and morpho-structural data, for the detailed investigation of a complex very slow rock slope deformation successfully unravelling its mechanisms, temporal trends of activity and forcing factors. Ground-truthing by means of GPS data further prove that, in the context of very slow rock deformations, PSI data are useful for a first-order characterization of slope activity and kinematics, but often fail to capture local scale spatial segmentation, temporal trends and associated mechanisms.</p><p>Our approach prove to be effective in providing key information for the definition of possible evolutive scenarios for risk analysis and mitigation of a widespread, yet challenging class of slope instabilities.</p>

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 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.

Numerical Simulation on Failure Mechanism of Rock Slope Using RFPA

2011 ◽  
Vol 50-51 ◽  
pp. 568-572 ◽  
Author(s):  
Nu Wen Xu ◽  
Chu Nan Tang ◽  
Chun Sha ◽  
Ru Lin Zhang
Keyword(s):  
Rock Slope ◽  
Slip Surface ◽  
Process Analysis ◽  
Failure Process ◽  
Numerical Code ◽  
Natural State ◽  
Left Bank ◽  
Good Tool ◽  
Deep Rock ◽  
The Stability

This research applied a numerical code, RFPA2D (Realistic Failure Process Analysis) to evaluate the stability and investigate the failure mode of the high rock slope during excavations based on Strength Reduction Method (SRM). The corresponding shapes and positions of the potential slip surfaces are rationally simulated in different stages, and the related safety coefficients are obtained, which agrees well with the allowable minimum safety factors of the slope. The numerical results show that the safety coefficient drops from 1.25 at the natural state to 1.09 after excavation, and then increases to 1.35 after slope reinforcement. Moreover, the potential slip surface of the left bank moves into deep rock mass after taking support measures, which demonstrates the reinforcement is reasonable and efficient. The study shows that cracks and faults will cause crucial influences on the slope stability, and RFPA2D is a good tool to directly display the potential slip surface of the slope, which will offer valuable guidance for bolt support.

Rock slope deformation mechanism in the Cihaxia Hydropower Station, Northwest China

2014 ◽  
Vol 74 (3) ◽  
pp. 943-958 ◽  
Author(s):  
Zelin Zhang ◽  
Gao Liu ◽  
Shuren Wu ◽  
Huiming Tang ◽  
Tao Wang ◽  
...  
Keyword(s):  
Deformation Mechanism ◽  
Rock Slope ◽  
Northwest China ◽  
Slope Deformation ◽  
Hydropower Station

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 Multiple rock-slope failures from Mannen in Romsdal Valley, western Norway, revealed from Quaternary geological mapping and 10Be exposure dating

The Holocene ◽  
2018 ◽  
Vol 28 (12) ◽  
pp. 1841-1854 ◽  
Author(s):  
Paula Hilger ◽  
Reginald L Hermanns ◽  
John C Gosse ◽  
Benjamin Jacobs ◽  
Bernd Etzelmüller ◽  
...  
Keyword(s):  
Slope Failure ◽  
Rock Slope ◽  
Significant Risk ◽  
Geological Mapping ◽  
Slope Instability ◽  
Permafrost Degradation ◽  
Geomorphological Mapping ◽  
Exposure Dating ◽  
Western Norway ◽  
Air Temperatures

Oversteepened valley walls in western Norway have high recurrences of Holocene rock-slope failure activity causing significant risk to communities and infrastructure. Deposits from six to nine catastrophic rock-slope failure (CRSF) events are preserved at the base of the Mannen rock-slope instability in the Romsdal Valley, western Norway. The timing of these CRSF events was determined by terrestrial cosmogenic nuclide dating and relative chronology due to mapping Quaternary deposits. The stratigraphical chronology indicates that three of the CRSF events occurred between 12 and 10 ka, during regional deglaciation. Congruent with previous investigations, these events are attributed to the debuttressing effect experienced by steep slopes following deglaciation, during a period of paraglacial relaxation. The remaining three to six CRSF events cluster at 4.9 ± 0.6 ka (based on 10 cosmogenic 10Be samples from boulders). CRSF events during this later period are ascribed to climatic changes at the end of the Holocene thermal optimum, including increased precipitation rates, high air temperatures and the associated degradation of permafrost in rock-slope faces. Geomorphological mapping and sedimentological analyses further permit the contextualisation of these deposits within the overall sequence of post-glacial fjord-valley infilling. In the light of contemporary climate change, the relationship between CRSF frequency, precipitation, air temperature and permafrost degradation may be of interest to others working or operating in comparable settings.

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