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 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 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.

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.

scholarly journals STABILITY OF RUBBLE MOUND BREAKWATERS WITH A BERM

2012 ◽  
Vol 1 (33) ◽  
pp. 10
Author(s):  
Marcel Van Gent ◽  
Gregory M. Smith ◽  
Ivo Van der Werf
Keyword(s):  
Rock Slope ◽  
Slope Angle ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Test Results ◽  
Physical Model Tests ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters ◽  
Rock Size

The stability of rock slopes with a horizontal berm has been studied by means of physical model tests. This paper is focussed on the rock slope stability of the slopes above and below the berm. By applying a berm the rock size can be reduced compared to the required rock size for a straight slope without a berm. This reduction can be significant for the slope above the berm. The influence of the slope angle (1:2 and 1:4), the width of the berm, the level of the berm, and the wave steepness have been investigated. Based on the test results prediction formulae have been derived to quantify the required rock size for rubble mound breakwaters with a berm.

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.

scholarly journals ENGINEERING GEOLOGICAL ASSESSMENT OF THE ROCK SLOPE STABILITY ALONG THE PROPOSED LERABIRE ROAD IN THE MERGASUR CITY, KURDISTAN, IRAQ

2020 ◽  
Vol 53 (2F) ◽  
pp. 65-82
Author(s):  
Rebaz Qader
Keyword(s):  
Slope Stability ◽  
Rock Slope ◽  
Slope Angle ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Stability Of Slopes ◽  
The Stability ◽  
High Degree ◽  
Marly Limestone ◽  
Failure Possibility

The study of slope stability along the proposed Lerabire road in the Mergasur town, in Erbil city, Kurdistan region of NE-Iraq is carried out. To evaluate the stability of slopes, twenty stations were selected along the mentioned road, two stations in the rock slopes of the Shiranish Formation, eleven stations in the Bekhme Formation, six stations in the Qamchuqa Formation, and one station in the Sarmord Formation. In this study, the stability of rock slopes has been evaluated by the Landslide Possibility Index system. The results of the Landslide Possibility Index category in the rock slopes along the proposed Lerabire road ranges from a very low to low for rock slopes in stations 1 and 2 (marl and marly limestone of the Shiranish Formation, Moderate for rock slopes in stations 3, 4 and 19 (limestone of the Bekhme Formation), High for rock slopes in the stations 5, 6, 7, 8, 9, 10, 11 (limestone of the Bekhme Formation), stations 12, 17 (limestone and marly limestone of the Qamchuqa Formation), station 20 (limestone of the Sarmord Formation and very high for rock slopes in the stations 13, 14, 15, 16 (limestone and marly limestone of the Qamchuqa Formation), station 18 (limestone of the Bekhme Formation). According to Landslide Possibility Index category, the hazard category is Low in station 1 in the Shiranish Formation, but in station 2, 3, 4 and 19 are Moderate, moreover, in the station 5, 11, 12, 17, 18 and 20 are high. The rock slope assessment indicated that the height of the slope face, slope angle, a high degree of weathering, and discontinuities spacing are the factors that increase the failure possibility. To prevent landslide the ditch method is used in the Shiranish Formation rock slopes, the reinforcement techniques are used in the Behkme Formation rock slopes and rock removal methods are used in Qamchuqa and Sarmord Formation rock slopes.

scholarly journals Stability Analysis of Jointed Rock Slope by Strength Reduction Technique considering Ubiquitous Joint Model

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Ruili Lu ◽  
Wei Wei ◽  
Kaiwei Shang ◽  
Xiangyang Jing
Keyword(s):  
Rock Slope ◽  
Reduction Method ◽  
Domain Size ◽  
Jointed Rock ◽  
Strength Reduction ◽  
Hydropower Station ◽  
Strength Reduction Method ◽  
Vertical Side ◽  
The Stability ◽  
Jointed Rock Slope

In order to study the failure mechanism and assess the stability of the inlet slope of the outlet structure of Lianghekou Hydropower station, the strength reduction method considering the ubiquitous joint model is proposed. Firstly, two-dimension numerical models are built to investigate the influence of the dilation angle of ubiquitous joints, mesh discretization, and solution domain size on the slope stability. It is found that the factor of safety is insensitive to the dilation angle of ubiquitous joints and the solution domain size but sensitive to the mesh discretization when the number of elements less than a certain threshold. Then, a complex three-dimension numerical model is built to assess the stability of the inlet slope of the outlet structure of Lianghekou Hydropower station. During the strength reduction procedure, the progressive failure process and the final failure surface of the slope are obtained. Furthermore, the comparison of factors of safety obtained from strength reduction method and analytical solutions indicates that the effect of vertical side boundaries plays an important role in the stability of jointed rock slope, and the cohesive force is the main contribution to the resistant force of vertical side boundaries.

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 Prediction of the Shear Failure of Opened Rock Fractures and Implications for Rock Slope Stability Evaluation

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Yingchun Li
Keyword(s):  
Shear Strength ◽  
Rock Slope ◽  
Shear Failure ◽  
Rock Slope Stability ◽  
Rock Fractures ◽  
Asperity Contact ◽  
Direct Shear Tests ◽  
Proposed Model ◽  
The Stability ◽  
New Criterion

Rock slope commonly fails due to the shear failure of rock fractures. Shear strength of rock fractures are reduced substantially once the fracture surfaces are mismatched or opened. We propose a new criterion to predict the shear strength of rock fractures in different opening states. The degree of interlocking representing the true asperity contact area is incorporated into the modified model of Saeb and Amadei. The effect of fracture opening on asperity dilation and degradation is separately considered. The transitional stress that is a critical parameter involved in the model is analytically determined based on energy consideration. The new model is validated with experimental results from direct shear tests on synthetic fractures with regular-shaped asperities. Good agreement between the analytical solution and the experimental data confirms the capacity of the proposed model. Therefore, the model has great potential for assessing the stability of rock slopes where fractures are often opened due to stress relief and engineering disturbances.

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