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.

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.

APPLICATION OF BLOCK THEORY MODELING ON SPATIAL BLOCK TOPOLOGICAL IDENTIFICATION TO ROCK SLOPE STABILITY ANALYSIS

2013 ◽  
Vol 11 (01) ◽  
pp. 1350044 ◽  
Author(s):  
SHUHONG WANG ◽  
PENGPENG NI
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Rock Slope ◽  
Limit Equilibrium ◽  
Slope Stability Analysis ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Block Theory ◽  
Joint Plane ◽  
Identification Techniques

Rock slopes stability has been one of the fundamental issues facing geotechnical engineering researchers. Due to the pre-existing joints, the intactness of the rock is weakened. The mechanical characteristics are changed correspondingly along with joint-induced stress redistribution within the rock mass if the sliding limit at the joint or part of it is exceeded. In this study, spatial block topological identification techniques are applied to distinguish all blocks cut by 3D finite random or fixed discontinuities. Based on the available photographic information of rock slopes, the sliding forces and the corresponding factor of safety are evaluated through limit equilibrium conditions by the classic block theory. The rock slope stability analysis software, GeoSMA-3D (Geotechnical Structure and Model Analysis), satisfying the requirements of spatial block modeling, joint plane simulation, key block identification and analysis and sliding process display, was developed. The application of such a software on the analysis of a rock slope, which is located near the inlet of Daiyuling No. 1 tunnel on the Zhuanghe–Gaizhou highway networks, was performed. The assessed results were compared with the monitored data to validate the effectiveness of such software.

scholarly journals AN EVALUATION OF ROCK SLOPE STABILITY USING LIMIT EQUILIBRIUM ANALYSES

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Faridha Aprilia ◽  
I Gde Budi Indrawan
Keyword(s):  
Slope Stability ◽  
Rock Slope ◽  
Limit Equilibrium ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Plane Failure ◽  
General Limit ◽  
The Stability ◽  
Equilibrium Analyses ◽  
Limit Equilibrium Analyses

The stability of rock slopes is controlled by several factors, such as the intact rock strength, discontinuity characteristics, groundwater condition, and slope geometry. Limit equilibrium (LE) analyses have been commonly used in geotechnical practice to evaluate the stability of rock slopes. A number of methods of LE analyses, ranging from simple to sophisticated methods, have been developed. This paper presents stability analyses of rock slopes at the Batu Hijau open mine in Sumbawa Barat using various methods of LE analyses. The LE analyses were conducted at three cross sections of the northern wall of the open mine using the Bishop Simplified, Janbu Simplified, Janbu Generalised, and General Limit Equilibrium (GLE) methods in Slide slope stability package. In addition, a Plane Failure (PF) analysis was performed manually. Shear strength data of the discontinuity planes used in the LE analyses were obtained from back analyses of previous rock slope failures. The LE analysis results showed that the rock slopes were likely to have shallow non-circular critical failure surfaces. The factor of safety (Fs) values obtained from the Bishop Simplified, Janbu Simplified, Janbu Generalised, and GLE methods were found to be similar, while the Fs values obtained from the PF method were higher than those obtained from the more rigorous methods. Keywords: Batu Hijau mine, Bishop Simplified, Janbu Simplified, Janbu Generalised, limit equilibrium analyses, general limit equilibrium, rock slope stability, plane failure.

Rock Slope Stability Analysis Based on FLAC3D Numerical Simulation

2012 ◽  
Vol 170-173 ◽  
pp. 375-379
Author(s):  
Hao Wang ◽  
Zi Xiong Chen ◽  
Dong Ming Zhang
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Rock Slope ◽  
Static Stability ◽  
Slope Stability Analysis ◽  
Slope Instability ◽  
Rock Slope Stability ◽  
Economic Losses ◽  
Geological Conditions ◽  
Geological Factors

The rocky slope instability has brought great danger to human activity, and often causes economic losses, property damage and casualties, also can cause huge overhead expenses. Rock slope stability analysis must understand the geological conditions as the foundation, be under the analysis to effects of geological factors of rock slope stability, be under the premise of analysis to the engineering geological factors and then make evaluation, this is the best method of analysis and evaluation of stability of rock slope effective. This paper utilizes quick Lagrange difference analysis (FLAC3D) to Zhu Jiadeng landslide in Chongqing, the numerical simulations are to determine the landslide static stability, and provide the basis for management.

scholarly journals Assessment of a Modified Rock Mass Classification System for Rock Slope Stability Analysis in the Q-system

2015 ◽  
Vol 19 (2) ◽  
pp. 147-152 ◽  
Author(s):  
Davood Fereidooni ◽  
Gholam Reza Khanlari ◽  
Mojtaba Heidari
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
Classification System ◽  
Rock Slope ◽  
Rock Mass Classification ◽  
Classification Systems ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
El Sistema ◽  
Mass Classification

<p>This paper explores the applicability of a modified Q classification system and its component parameters for analysis and conclusion of site investigation data to estimate rock slope stability. Based on the literature, Q classification system has high applicable potential for evaluation of rock mass quality. Therefore, in this study, it was used with RMR and SMR rock mass classification systems to assess stability or instability of different rock slopes along the Hamedan-Ganjnameh-Tuyserkan road, Hamedan province west of Iran. Furthermore, a modified rock mass classification system namely Slope Quality Rating (SQR) was proposed based on the correction of the Q classification parameters and calculating some new parameters such as dip and strike of discontinuities and the method of rock excavation or blasting. For this purpose, the SMR and RMR rock mass classifications were also needed. By measuring SQR for different rock slopes, it will be possible to measure Slope Mass Rating (SMR).</p><p> </p><p><strong>Evaluación del sistema Q modificado de clasificación del macizo rocoso para el análisis de estabilidad de pendiente de roca</strong></p><p> </p><p><strong>Resumen</strong></p>Este artículo explora la aplicabilidad del sistema de clasificación Q modificado y sus parámetros para analizar y determinar la información estimada de estabilidad de pendiente de roca en el sitio determinado de estudio. Según la literatura, el sistema de clasificación Q tiene un alto potencial de aplicabilidad paral a evaluación de la calidad del macizo rocoso. En este estudio además se utilizó el sistema Q junto con los sistemas Índice de Masa de Pendiente (SMR) y Clasificación Geomecánica de Bienawski (RMR) para evaluar la estabilidad e inestabilidad de diferentes pendientes rocosas en la carretera Hamedan-Ganjnameh-Tuyserkan, de la provincia de Hamedan, en el Oeste de Irán. Además, se propone el Índice de Calidad de Pendiente (SQR), un sistema de clasificación de macizo rocoso modificado, a partir de la corrección de los parámetros de clasificación Q y el cálculo de nuevos parámetros como pendiente y caída de las discontinuidades y el método de excavación o explosión de la roca. Para esta propuesta también se utilizaron las clasificaciones SMR y RMR. La medición SQR en diferentes pendientes hizo posible el cálculo del sistema SMR.</p>

scholarly journals Stability Assessment of High and Steep Cutting Rock Slopes with the SSPC Method

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Hongliang Tao ◽  
Guangli Xu ◽  
Jingwen Meng ◽  
Ronghe Ma ◽  
Jiaxing Dong
Keyword(s):  
Slope Stability ◽  
Rock Slope ◽  
Equilibrium Analysis ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Evaluation Indexes ◽  
Weathering Degree ◽  
Slope Rock ◽  
The Stability

The stability of high rock slopes has become a key engineering geological problem in the construction of important projects in mountainous areas. The original slope stability probability classification (SSPC) system, presented by Hack, has made obvious progress and been widely used in rock slope stability analysis. However, the selection and determination of some evaluation indexes in the original SSPC method are usually subjective, such as intact rock strength and weathering degree. In this study, the SSPC method based on geological data obtained in the prospecting tunnels was presented and applied. According to the field survey and exploration of the prospecting tunnels, the weathering degree of the slope rock mass was evaluated. The empirical equation for the maximum stable height of the slope was applied to the slope stability evaluation in the presented SSPC method. Then, the slope stability probability of numerous cutting slopes in the sandstone unit was evaluated using the presented system. Results of the Geostudio software based on the limited equilibrium analysis of the investigated slopes were compared with the results obtained by the SSPC method. The results indicate that the SSPC method is a useful tool for the stability prediction of high and steep 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

&lt;p&gt;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&lt;sup&gt;3&lt;/sup&gt; and resulted in a large landslide on 29th July 2019 with the magnitude of the volume of 37234 m&lt;sup&gt;3&lt;/sup&gt;, 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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;Keywords: Wedge failure; Joint persistence; Groundwater; Rock slope stability.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Soil-Rock Slope Stability Analysis by Considering the Nonuniformity of Rocks

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Shunqing Liu ◽  
Xianwen Huang ◽  
Aizhao Zhou ◽  
Jun Hu ◽  
Wei Wang
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Relative Position ◽  
Rock Slope ◽  
Slope Stability Analysis ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Analysis Method ◽  
Slope Surface ◽  
The World

Soil-rock slopes are widely distributed around the world, while the commonly adopted method by simplifying it as a uniform media tends to be excessively conservative. In this study, a slope stability analysis method considering the nonuniform characteristics of rocks was proposed. It was found that the distribution, relative position, and shape of rock have significant effect on slope stability. For the influence of distribution, large rocks at the foot of slope have the most significant effect on slope stability while the effect is insignificant when the rocks are on the slope surface. In terms of the relative position of rocks, four plastic expansion modes of bypass, diversion, inclusion, and penetration were put forward through the analysis on the expansion mode of the plastic zone. Moreover, rock shape also has influence on slope stability.

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