ISRM 2023 - PUBLICATIONS

T17: Rock slope engineeringArmin RODUNER, Helene LANTER, Manuel EICHERGeobrugg AG, SwitzerlandLatest developments to increase the quality of flexible rockfall protection barriersTo ensure that flexible rockfall barriers are able to effectively stop the dynamic impact of rockfall, several guidelines have been introduced worldwide since 2001. However, long-term experience shows that other, “natural”, load cases happen which are not covered by guidelines or certification tests. Proposed substitute scenarios, for these natural load cases, are now treated by means of 1:1 field tests to increase the quality of rockfall protection systems and to offer more safety through additional test procedures. At the same time, the more stringent requirements are intended to meet all the guidelines and practical instructions applicable in Europe. In this paper, the different guidelines are discussed, the load case scenarios and their requirements are described in detail and the adaptations to the rockfall protection systems are presented. | Rockfall, 1:1 field tests, Flexible protection barrier, Multiple Loading
T17: Rock slope engineeringBattista TABONI (1), Gessica UMILI (1), Anna Maria FERRERO (1), Simone BLANC (2), Filippo BRUN (2), Stefano BRUZZESE (2), Luca M. ALBERTELLI (3), Iuri D. TAGLIAFERRI (3)1: University of Turin, Department of Earth Sciences; 2: University of Turin, Department of Agricultural, Forest and Food Sciences; 3: Land&CogeoThe influence of a heavy storm on a slope subject to rockfall phenomena: the Bazena case studyThe evolution of rockfall phenomena depends on both rock mass and slope characteristics: variations in cover, morphology or vegetation induced by intense weather events can have huge consequences. Investigating these effects is required to assess the effectiveness of existing protection structures. This study focuses on the Bazena case (Brescia, Italy), a slope subject to rockfall phenomena, crossed by a provincial road connecting two valleys. Originally the slope was covered by a coniferous forest, which was almost completely destroyed by an extremely intense storm in 2018. In this context, the ASFORESEE model was applied to understand the value of the protection provided by the forest, over a period of 25 years. The output of ASFORESEE and other evaluations here proposed show that the forest played an active role in protecting the provincial road against rockfall phenomena. This work aims to highlight the potentiality of combining nature-based solutions and flexible barriers. | Rockfall, flexible barrier, nature-based solution, forest, ecosystem service, economic evaluation
T17: Rock slope engineeringDragana SLAVKOVIĆ (1), Aljoša MITIĆ (2), Miloš MARJANOVIĆ (3)1: Institute of transportation CIP, Nemanjina6/IV, Belgrade, Serbia; 2: Central road laboratory LLC, Zivorada Petrovica 13, Novi Sad, Serbia; 3: University of Belgrade, Faculty of Mining and Geology, Djusina 7, Belgrade, SerbiaComparing different rock mass classifications using field and point cloud data on a rock cutClassifying rock masses implies a systematic quantification of various field data, lately including point clouds acquired using LiDAR or photogrammetric techniques. They have been proven useful for extraction of additional information and more confident rock mass classification in inaccessible parts of the slope. In this work, a rock cut along the railway Knjaževac – Zaječar in Serbia was analyzed using conventional field mapping and data extracted from point clouds. Basic RMR, SMR and Q-slope classifications were used for rock mass characterization. Extraction from the point cloud was applied beyond the accessibility line (>2 m), and included determination of RQD, joint spacing and orientation. The rock mass is split into three zones, wherein RMR score equaled 64, 57, and 56 for Zone 1, 2 and 3, respectively, whereas SMR score equaled 49, 42, and 41, respectively. A better distinction between the zones was achieved using Q-slope score, totaling 1.75, 0.66 and 0.31, respectively. | Rock Mass Classifications, RMR, SMR, Q-slope, LiDAR
T17: Rock slope engineeringHiroyuki HONDA (1), Yasuhiro MITANI (1), Hisatoshi TANIGUCHI (1), Ibrahim DJAMALUDDIN (2), Yurino KAWAURA (1)1: Kyushu University, Japan; 2: Hasanuddin University, IndonesiaRock slope stability management along the road by machine learning through databasing disaster prevention recordsIn the maintenance of roads through mountainous terrain, inspections for rockfall and rock collapse are not conducted on all the targeted roads, thus resulting in disasters outside the scope of the inspections. In this study, 0.5 m Laser Profiler (LP) along National route 210, Oita, Japan, with a total length of 100 km is applied to generate Digital Elevation Model, and the division of slope units is created based on the inclination angles and their distribution. Secondly, the database is prepared by the inspection records (2006-2021) that machine learning will use as training data to create a risk evaluation model. Finally, we were able to extract potentially dangerous slopes that have not been inspected so far in the study area and clarified the inspection priority. | steep cliff, rockfall, rock collapse, road disaster prevention record, supervised learning
T17: Rock slope engineeringMarco BARLA (1), Santina AIASSA (2), Francesco ANTOLINI (2), Alessandra INSANA (1), Andrea PERINO (2)1: Dept. Of Structural, Geotechnical and Building Engineering, Politecnico di Torino, Italy; 2: Geosolving srl, Torino, ItalyDiscontinuum modelling of slope instability as a support tool for risk managementThe definition of threshold values within an early warning system for monitoring of an instability phenomenon in nearly real time represents a key step. Several approaches exist in literature, among which numerical modelling for the simulation of instability scenarios is the least common. The present paper illustrates how discontinuum numerical modelling can be used as a support tool for risk management with reference to a slope instability case study. The aim is to investigate the displacement rate that can anticipate the instability phenomena. To highlight the reliability of the models, back-analysis of a past instability event is carried out and a time-scaling coefficient is defined, and eventually validated, to match numerical results and monitored data. Based on such results, that reproduce the slope displacement trends from triggering to collapse, thresholds and related timespans to be adopted within the existing monitoring system are suggested. | Slope Stability, Discontinuum Modelling, Risk Management, Thresholds
T17: Rock slope engineeringRyan Alexander ZIEBARTH (1), Andrew G. CORKUM (1), Ian R. STILWELL (2), Derek KINAKIN (2)1: Dalhousie University, Canada; 2: BGC Engineering IncA Parametric Study Illustrating the Effects of Moderately Anisotropic Rock Strength on the Stability of Large Slopes using Limit Equilibrium AnalysisAccounting for moderately anisotropic conditions where one or more dominant structure sets affect slope stability analysis is challenging. Most analysis methods and software assume isotropic behaviour that better suits randomly jointed rock masses. Some methods for assessing anisotropic formations (bedding, schistosity, etc.) exist, but the computationally expensive Synthetic Rock Mass approach is the only method to capture moderately anisotropic behaviour. Therefore, guidance is needed to identify when a rock mass is moderately anisotropic. The limit equilibrium method software Slide2 was used to perform a parametric study on the Generalized Anisotropic strength model for a hypothetical rock slope. The key contributors to determining if a rock mass is moderately anisotropic were the shear strength (cohesion only) of the weak plane was a quarter or less of the intact strength, the angular distance between two joint sets was approximately 30°, and the angle of anisotropy was within 15° of the slope face. | Rock mass strength, Anisotropy, Slope Stability, Slide2
T17: Rock slope engineeringZhibo JIA (1), Yan BAO (1), Lianjin TAO (1), Jin BIAN (2), Hu WEN (3), Haixiang ZHANG (3)1: The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing, China; 2: College of Engineering, Guangdong Ocean University, Zhanjiang, China; 3: Beijing University of Technology, Beijing, ChinaSlope safety assessment based on dynamic anchor forceAnchor cable is widely used in rock slope reinforcement. In the design, the force of the anchor cable is often simplified as a constant load, which cannot reflect the deformation. To accurately evaluate the stability of the slope reinforced with anchor cables under earthquake load, the nonlinear mechanical model is introduced. Based on the Newmark method, the displacement formula is derived. The differences between the two models are compared under the framework of vulnerability. The results show that: 1) Deformation of anchor cables due to slope sliding. The anchor force is showing an increasing trend. 2) The stability of the slope is related to the ground motions. Vulnerability analysis can be used for quantitative analysis of slope safety. 3) The slope considering the change of anchor cable force has a greater probability of instability. Simplifying the anchor cable to constant loads may lead to an underestimation of the danger. | Anchor cable, Slope, displacement, Newmark, Earthquake
T17: Rock slope engineeringJavier GONZÁLEZ-GALLEGO, José ESTAIRE, María SANTANACEDEX, SpainUse of representative values of geometrical properties of discontinuities in rock slope verifications according to EC7This work aims to obtain representative values for the geometrical properties of families of discontinuities, within the criteria set out in the final draft of Eurocode 7 (EC7), by a conservative estimation of the mean value and not as a purely average value, as it is done for the rest of the geotechnical properties. This paper describes how to use the EC7 methodology to obtain representative values for the geometrical properties of discontinuities. Moreover, an example is included to compare the safety factor of a wedge using this EC7 methodology and the derived from normal practice. This example deals with a typical issue where the data collection is done manually and the number of values is small. With the results obtained, some questions arise as to what should be the correct way to obtain a representative value for the case of wedges in rock. | Geometrical properties, Eurocode, rock slope stability
T17: Rock slope engineeringClarence BUTCHER (1), Olivier BUZZI (1), Anna GIACOMINI (1), Robert BERTUZZI (2), Vaughan GRIFFITHS (3)1: The University of Newcastle, Australia; 2: PSM, Engineering Consultants; 3: Colorado School of Mines, U.S.A.Capturing the roughness of discontinuity traces in the field with high accuracy: the effect of photograph resolutionThe recently developed stochastic approach to discontinuity shear strength (StADSS) avoids scale effects by predicting peak and residual shear strength using full scale discontinuity data. StADSS has been applied to mortar replicas of perfectly matched specimens in the laboratory, but application to large in situ discontinuities is yet to be undertaken. Paramount to the in-situ application of StADSS is the adequate collection of discontinuity roughness information. This paper presents an approach to digitize the seed trace of in-situ discontinuities. Several identical images of a seed trace with varying pixel densities were analyzed to determine what pixel to millimeter ratio was sufficient to enable a Gaussian distribution of gradients to develop. It was found that a pixel density of 6-7 pixels per millimeter of seed trace length was sufficient to develop the parameters of a suitable Gaussian distribution of gradients, which could then be used for further statistical analysis. | Discontinuity, Roughness, Scale Effect, Shear Strength
T17: Rock slope engineeringMariella ILLEDITSCH (1,2), Alexander PREH (1,2), Johann Thomas SAUSGRUBER (3)1: pi Geotechnik ZT GmbH, Austria; 2: Vienna University of Technology, Austria; 3: Federal Ministry Republic of Austria - Agriculture, Forestry, Regions and Water Management, AustriaThe Correct Way to use the Hoek-Brown Strength Criterion for Slope Stability Analysis on the Example of Vals (Tyrol/Austria)The Hoek-Brown (HB) strength criterion is increasingly used to investigate the stability of slopes. However, it is still partly unclear how this should be implemented for slopes in a correct way. There are two ways to use the HB strength criterion. On the one hand, the HB parameters can be converted into equivalent Mohr-Coulomb (MC) parameters by estimating a suitable range of minor principal stresses. The result is a linear failure envelope. On the other hand, the nonlinear HB failure envelope can be applied directly by calculating apparent MC parameters for each point of the HB failure envelope. The result is a nonlinear failure envelope. Equivalent MC model parameters are usually used in numerical model calculations. However, this approach has some disadvantages. On the example of Vals, where a rock fall of about 117,000 m³ occurred in December 2017, a new method for using apparent MC parameters is presented. | Rock Slope, Hoek-Brown Criterion, Stability Analysis, Strength Reduction Method, Continuum Mechanics, Equivalent Mohr-Coulomb Parameters
T17: Rock slope engineeringMiosoty BAUTISTA (1), Juan Carlos COBIAN SALAS (1), Jessica LOPEZ (1), Neil BAR (2), Niccolò COLI (3), Francesco COPPI (3), Andreas GAICH (4), Markus PÖTSCH (4), Miriam BAUMGARTNER (4), Alison MCQUILLAN (5)1: Barrick Gold Corporation; 2: Gecko Geotechnics LLC; 3: IDS GeoRadar SRL; 4: 3GSM GmbH; 5: Rocscience IncDeveloping a Digital Twin: A Semi-Brittle Slope Failure Case Study from Pueblo Viejo Gold MineTechnological improvements in geotechnical mapping, modelling and monitoring now allow a digital twin to be developed and maintained in parallel with mining operations. That is, the routine use of aerial photogrammetry, semi-automatic rock mass characterization, three-dimensional slope stability modelling and ground-based interferometric synthetic aperture radar monitoring allow near real-time comparison of modelled and realized ground conditions. This is critical for reconciling the effectiveness of geotechnical models for predicting future slope stability (or instability). This paper presents a semi-brittle slope failure case study from Pueblo Viejo gold mine which was managed using a digital twin approach. The near real-time comparison of the three-dimensional model with observed slope conditions allowed critical structures to be added to the geotechnical model as mining progressed. This led to the identification of a high risk area that would not have been identified if the digital twin was not implemented & maintained during mining. | Slope stability analysis, photogrammetry, radar monitoring, digital twin
T17: Rock slope engineeringNurkhair TELEU, Neil BAR, Herman ZLOBIN, Philipp MOHRKAZ MInerals, KazakhstanRock slope design and residual risk management for Aktogay Copper Mine, KazakhstanAktogay is a large open pit copper mine in Kazakhstan. Several geotechnical investigations have been completed from initial scoping and feasibility studies to continuous improvement studies during mining. Rock slope design has involved several phases of stability analyses for various stages and the life-of-mine open pit. With the progression of mining in the pit, ground conditions at the mine are becoming more apparent and uncertainty is progressively reduced. This paper briefly describes the slope stability modelling approaches used to understand and communicate geotechnical risks and opportunities for integration with a complex mine plan and sequence. A combination of 3D limit equilibrium and finite element analysis was incorporated into slope stability assessments for future slope excavation stages. The models have been developed with the intention of being digital twins to actual mine progression, with routine updating as engineering geological features are validated and updated with new exposures and additional site investigations. | 3D slope stability analysis, risk management, digital twin, mining
T17: Rock slope engineeringMiguel CANO (1), José Luis PASTOR (1), Roberto TOMÁS (1), Adrián RIQUELME (1), Luis JORDÁ (2), José SERÓN (3)1: University of Alicante, Spain; 2: Universidad Politécnica de Madrid, Spain; 3: Universitat Politècnica de València, SpainA critical look to the practical use of Rock Mass Rating (RMR) and Slope Mass Rating (SMR)RMR and SMR are two of the most applied classifications for tunnels and slopes, respectively, excavated in rock masses. Five parameters are used to compute the basic RMR classification for each discontinuity set. However, it is not clarified the whole Rock Mass RMR value. Here, the rock engineering community interprets the possibilities of calculating RMR in different ways. In addition, given that SMR is calculated from RMR by adding four correction factors, different interpretations arise. In this work, different cases of rock masses were analysed and both indexes, RMR and SMR, were assessed using different interpretations of RMR calculations. From this analysis, it can be concluded that, occasionally, there is a significant difference in the RMR and SMR values obtained depending on the followed procedure. | RMR, SMR, rock engineering, interpretation criteria, critical look
T17: Rock slope engineeringKripamoy SARKAR, Avishek DUTTAIndian Institute of Technology (Indian School of Mines) Dhanbad, Jharkhand, IndiaComparative study of finite and distinct element methods for stability assessment of a jointed rock slopeEvery year the Himalayan regions of India experience several devastating landslides, which not only claim the lives of people, but also disrupt transportation facilities and the environment in general. The present study deals with assessing the instability conditions of a road-cut slope, under saturated conditions, using kinematic analysis with the help of Dips software, and two numerical simulation techniques, viz., the finite and the distinct element methods using the software packages RS2 and UDEC respectively. Probable mode of failure represented by the distinct element modeling agrees well with that predicted by the kinematic analysis of the slope. The results of the analyses suggest that the distinct element approach is a better suited technique for stability analysis of heavily jointed rock slopes compared to the finite element approach. The studied slope has been found to be unstable, hence few remedial measures have been suggested to improve its strength. | Road-cut slope, Numerical simulation, Finite Element Method, Distinct Element Method, Stability analysis, Himalayas
T17: Rock slope engineeringTao XU (1), Zhiguo LI (1), Tianhong YANG (1), Xiaobing ZHENG (1), Wancheng ZHU (1), Tengfei FU (2)1: Northeastern University, People's Republic of China; 2: CSCEC-TAISEI Construction Ltd., Beijing, ChinaSub-critical crack growth based time-dependent deformation model and its application to open-pit slope stabilityA subcritical crack growth based deformation model was established to describe the time-dependent deformation and fracturing of rock. In conjunction with the uniaxial compression test of rock, the microscopic parameters of the model were calibrated, and the accuracy of the creep model and parameter calibration were verified using uniaxial compressive creep tests. Finally, the established time-dependent deformation model of rock was applied to the time-dependent deformation analysis of a slope in the Fushun West open-pit mine. This study shows that the time-dependent deformation model of rock established in this study can effectively describe the accelerated stage of rock creep, and the simulation results agree well with the experimental results. After the continuous deformation, cracks are formed by the stress concentration at the bottom of the slope under the influence of unfavorable factors, which continuously extend to the top of the slope and form a sliding surface, resulting in unstable sliding. | rock slope, creep deformation, subcritical crack growth, slope stability, numerical simulations
T17: Rock slope engineeringKrishna Kanta PANTHI (1), Chhatra Bahadur BASNET (2)1: Norwegian University of Science and Technology (NTNU), Trondheim, Norway; 2: Clean Energy Consultant Pvt Ltd, Kathmandu, NepalRock cut slope excavated for Settling basins of Seti Khola Hydropower ProjectStability of a cut-slope at the headworks area of the hydropower projects is very important for smooth operation of hydropower plant. Underestimation during construction period may bring a catastrophic consequence. This manuscript presents overall assessment results of the rock cut slope excavated to accommodate two settling basins of Seti Khola Hydropower Project (22 MW) located at Lekhnath, Kaski, Nepal. The height of the cut slope is about 50 m and is among the most challenging part of the construction work. The cut slope is excavated in a highly schistose and deformed phyllite with interbedding of metasandstone layers. The evaluations are made on the overall rock mass and discontinuity characteristics. The results of detailed stability assessment using software program SLIDE in consideration with both normal and seismic loading conditions are presented. Final rock support measures are proposed to ascertain long-term stability of the cut-slope. | Settling basin, diversion dam, groundwater, earthquake, stability assessment
T17: Rock slope engineeringYago Machado Pereira de MATOS (1), Silvrano Adonias DANTAS NETO (2), Guilherme de Alencar BARRETO (2)1: University of Brasilia, Brazil; 2: Federal University of Ceará, BrazilModelling the shear behavior of clean rock joints using Adaptive Neuro-Fuzzy Inference SystemsCurrently, the development of accurate and reliable models for predicting the behavior of rock mass joints is one of the most common interests among researchers, engineers and geologists. An alternative to address this type of problem more efficiently can be neuro-fuzzy systems, which combine the advantages of Fuzzy Controllers and Artificial Neural Networks (ANN). Therefore, the objective of this paper is to use Adaptive Neuro-Fuzzy Inference Systems (ANFIS) to predict the shear strength and corresponding dilation of unfilled discontinuities of rock masses, incorporating the uncertainties of the variables that govern their shear behavior. It was found that the proposed ANFIS models can be considered a useful tool to predict the shear behavior of clean discontinuities, as they require only some information about the joints characteristics, the intact rock that constitutes their walls, and the boundary conditions imposed on them, without the need for costly and complex laboratory tests. | Clean rock joints, Shear behavior, Neuro-fuzzy, ANFIS, Modelling
T17: Rock slope engineeringÖmer AYDAN (1), Reşat ULUSAY (2), Jose PAVON (3), Nazli Tunar OZCAN (2)1: University of the Ryukyus, Okinawa, Japan; 2: Hacettepe University, Ankara, Turkey; 3: Jose Pavon & Asociados, Asuncion, ParaguayRock Mechanics Characterization of Columnar Sandstone of Cerro Koi (Paraguay) and Some Slope Stability Issues of the Associated Open PitsUnique columnar jointing in sandstone is observed in Cerro Koi site nearby Asuncion (Paraguay). The authors collected some sandstone columns and carried out on some physico-mechanical experiments on rock pieces for the rock mechanics characterization of this unique columns. The outcomes of experiments carried out rock mechanics characteristics of the columnar sandstone as well as frictional properties of natural column surface together with their base-friction angles are presented. Furthermore, the stability of the open pits is investigated and their short and long-term stability are discussed. | Cerro Koi, columnar jointing, sandstone, open pit, mechanical properties, stability, frictional properties
T17: Rock slope engineeringMuhammad JUNAID (1), Rini Asnida ABDULLAH (2), Radzuan SA'ARI (2)1: National University of Science and Technology; 2: Universiti Teknologi malaysiaEvaluation of Rock Mass Quality using Unmanned Aerial Vehicle Survey for Slope instability AssessmentRock mass quality (RQD) is the fundamental way of evaluation of rock mass quality in mining and geotechnical investigation. However, the estimation of RQD in morphological complex areas is difficult to obtain. In this research work, an unmanned aerial vehicle (UAV) survey was adopted to estimate the RQD at various locations along the slope using volumetric joint counts (Jv). At the centre of the slope, 72% of the data points represent fair rock, while 28% shows poor rock. In contrast, the 20 data point obtained towards the west included 90% of data points for fair rock while 10 % for good rock. Thus, based on his study it is concluded that UAV survey is an efficient way of characterization of rock mass quality. | Slope stability, UAV, RQD, characterization, rock mass evaluation
T17: Rock slope engineeringSuryajyoti NANDA, Satyam CHOUDHURY, Shantanu PATELIndian Institute of Technology Kharagpur, West Bengal, IndiaAssessment of structurally-controlled slope failure in a steeply dipping Iron ore mineExcavating an open pit mine with a steep angle considering both productivity and safety is a major challenge. The current work proposes a framework for slope design for a large open-pit iron ore mine with complex geological conditions. The joint properties of the steeply deposited mine are collected through face mapping and laboratory tests are done to obtain the intact rock and joint properties. The kinematic analysis of the initial slope design showed wedges forming in the benches. As a remedial measure, the wedge failure analysis is done for the bench scale and the most suitable pit design is selected by changing the slope angle and pit orientation. It was found that the optimized slope design in terms of both safety and productivity can be achieved at an overall slope angle of around 350 with a stripping ratio of approximately 3.5. | Pit slope design, Face mapping, Kinematic analysis, Wedge failure, Stripping ratio
T17: Rock slope engineeringCarlos Luis GARRIDO GARRIDO, Sergio SÁNCHEZ RODRÍGUEZ, Paula DEL POZO GARCÍAAECOM. Enterprise Capabilities EuropeInteraction between tunnels and slopes. Analysis of weak rock masses considering the Hoek-Brown failure criterionPrimary support design for tunnels close to a slope should consider the existing asymmetric stress state. Tunnel excavation imposes deconfinement around the cavity, which may affect the available margin of safety of the slope. For fair to good rock masses, the impact on the existing slope is mostly conditioned by the rock mass structure, even for shallow tunnels. This research is focused on analyzing the impact on the primary support needs for openings in weak rock masses, as well as the potential changes in the stability conditions of the slopes caused by shallow tunnels excavated near them. The Hoek-Brown failure criterion has been used for the parametric study carried out by means of numerical analysis. With these numerical simulations, the construction process of the tunnel is studied to analyze its influence on the existing slope stability, along with the corresponding effects on the support needs for different rock mass conditions. | Tunnel-slope interaction, slope stability, factor of safety, weak rock masses, Hoek-Brown failure criterion, numerical models
T17: Rock slope engineeringAmoussou ADOKO, Hayes ANYASODORSchool of Mining and Geosciences, Nazarbayev University, KazakhstanA reliability-based design approach for geotechnical domain modelling in pit slope designThe inherent variability of rock mass properties unavoidably leads to imprecisions in open pit geotechnical models, which can increase the likelihood of failures in pit slopes. To overcome this, a reliability-based design approach is advocated to allow for adequate consideration of the design’s uncertainties. In this study, the First Order Reliability Method (FORM) was used to determine the reliability of a pit slope design through a probability of failure. Data from the Bozshakol copper mine located in north Kazakhstan was used in this study. The input data for the FORM analysis were the rock mass properties and the slope design parameters corresponding to selected sectors of the pit. The reliability indices evaluated for each geotechnical domain show good agreement with the slope displacement observations. The results of this study illustrate the importance of a reliability-based design and its capability to be used as basis for improvement of pit slope design. | Reliability analysis, reliability index, probability of failure, open pit slope, geotechnical domain modelling, factor of safety
T17: Rock slope engineeringSom NATH (1,2), Ashok Kumar SINGH (3), Harsh Kumar VERMA (2), Nachiketa RAI (1)1: Indian Institute of Technology Roorkee, India; 2: CSIR-Central Institute of Mining and Fuel Research, Regional Research Centre Roorkee (UK) India; 3: CSIR-Central Institute of Mining and Fuel Research, Regional Research Centre Bilaspur (CG) IndiaEffect of blast damage zones on the stability of a Himalayan highway cut-slope ₋ continuum modelling approachHoek & Brown introduced the disturbance factor, "D," to their failure criteria in order to account for the critical effect of blast-induced damage zone in the assessment of the rock mass parameters. Considering the vital effect of blast damage extent on the surficial stability of jointed cut slopes, the present study examines the stability behavior of a jointed cut slope that had been excavated through rough blasting practice along NH-5 in dynamic Himalayan conditions in Himachal Pradesh, India. The effect of the blast damage zone on the stability behavior has been investigated through continuum-based Finite Element modeling. A parametric study has been done by assigning different damage factor ‘D’ to the damage zone of the rock slope. The results demonstrate the variability in safety factors of jointed cut-slopes in relation to the extent and degree of blast-induced rock mass damage of the disturbance zones. | Blast-induced damage zone, Highway slopes, Safety factor, Continuum modelling, Himalaya
T17: Rock slope engineeringCheng-Han LIN, Ming-Lang LINDepartment of Civil Engineering, National Taiwan University, TaiwanActivity and kinematic behaviors of gravitational slope deformation in the slate belt of TaiwanIn the slate belt of Taiwan, there have been numerous studies exploring landslide activity or gravitational slope deformation (GSD) since the 2009 Typhoon Morakot. However, studies evaluating the relationship between present-day activity and long-term deformation have been infrequent due to a lack of multi-temporal monitoring data and analysis tools. The Chingjing region, which contains many GSDs and famous rockslides, is one such region that requires further investigation in this context. This study aims to interpret the evolution of slate slope deformation from long-term kinematics to short-term activity. We first observe the surficial displacement rate during the period of 2018-2020 using multi-temporal InSAR analysis. The radar satellite-based surface observation was then supplemented with numerical analysis based on the distinct element method to characterize the sub-surface gravity-driven slope movement. Our results help explain the evolution of gravitational slope deformation in slate slopes and better assess rockslide hazards transferred from GSD. | Gravitational slope deformation, slate slope, multi-temporal InSAR analysis, distinct element modeling
T17: Rock slope engineeringMaria Teresa CARRIERO (1), Cesare COMINA (2), Anna Maria FERRERO (2), Maria Rita MIGLIAZZA (1), Battista TABONI (2), Gessica UMILI (2), Federico VAGNON (1), Sergio Carmelo VINCIGUERRA (2)1: Polytechnic of Turin, Turin, Italy; 2: University of Turin, Turin, ItalyGeotechnical and geophysical investigation of a rock mass for the design check of an ornamental stone quarryThe design of an open-pit quarry must continuously adapt to the real conditions of the excavation faces, to meet safety requirements and maximize the effectiveness of the operational process. The case study of an ornamental stone quarry characterized by great value and challenging excavation geometry is analyzed in this study. The exploited rock mass is characterized by a non-ubiquitous discontinuity distribution due to the presence of highly fractured bands, mainly parallel to the excavation faces. The discontinuity network needs to be analyzed to forecast the rock mass mechanical behavior during excavation. In this regard, the integration of geotechnical and geophysical surveys allows the rock mass to be studied from the surface to a considerable depth. Trace mapping on scaled digital images was combined with traditional geomechanical methods and GPR surveys, executed on the excavation faces, to assess the variability of discontinuity spacing and to characterize the fractured bands. | open-pit quarry, spacing, digital images, GPR, fracture band
T17: Rock slope engineeringMazlina RAZALI (1,2), Mohd Ashraf MOHAMAD ISMAIL (1), Sharan Kumar NAGENDRAN (3), Zuraini ZAINAL (3), Hayato TOBE (4), Kensuke DATE (5), Yasuhiro YOKOTA (5), Hamzah HUSSIN (6)1: School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Penang, Malaysia; 2: Centre for Civil Engineering, Universiti Teknologi MARA, Cawangan Pulau Pinang, Permatang Pauh Campus, Pulau Pinang, Malaysia; 3: Centre of Excellence for Engineering and Technology (CREaTE), Public Works Department (JKR), Alor Gajah, Melaka, Malaysia; 4: Rock Mechanics and Hydro-geology Group, Kajima Technical Research Institute, Kajima Corporation, Japan; 5: Kajima Technical Research Institute Singapore, Kajima Corporation, Singapore; 6: Department of Geoscience, Faculty of Earth Science, Universiti Malaysia Kelantan, Jeli, KelantanEvaluation of weathering effects by CIELAB color space and image analysis technique for interbedded metasedimentary rock in the northern region of Peninsular MalaysiaWeathering process affect the engineering behavior of rock masses, reduced strength, and structural stability. In addition to the prior technology, rapid weathering evaluation by CIELAB to characterize the rock surface color. The various colors appearing on the surface of the rock slope indicated the differential weathering grades of the rock mass. UCS-Schmidt obtained by the Schmidt hammer strongly validates the color changes and can be classified into different grades. A high value in redness (a*) and yellowness (b*) indicates the rock is weathered. The results were further revealed using image analysis to confirm the analysis. The weathering zoning processed by image analysis clearly interpreted different weathering grades. This study revealed the enhanced technique as an effective tool in the preliminary evaluation of weathering effect. | Image analysis, weathering, metasedimentary rock, CIELAB, Schmidt hammer
T17: Rock slope engineeringLal HRUAIKIMA (1), Mahendra SINGH (1), Sarada Prasad PRADHAN (1), Jaspreet SINGH (2)1: Indian Institute of Technology Roorkee, Roorkee, India; 2: Simon Fraser University, Burnaby, BC, CanadaSite specific joint spacing distribution of roadcut slopes in a selected stretch of national highway in Indian Garhwal HimalayasDue to extensive road widening project in the Himalayas, the roads experience huge instability problems especially during monsoon season. For the present study, 50 rock slope sites were considered over a stretch of 35 km on a national highway. The various attributes of discontinuities governing the slope failure were observed and the joint spacing in the stretch of the national highway is studied in detail. Detailed scanline survey was carried out and a database comprising more than about 6000 datapoints was generated. It is observed that the joints are spaced between 1 cm to 60 cm for the stretch of road. Statistical analysis of the joint spacing shows that most of the joint sets follow Exponential distribution, Weibull distribution, and lognormal distribution. Slope stability analysis was performed using the joint spacing data for all the slopes. It was observed that 50% of the slopes were susceptible to failure. | Discontinuities, Joint Spacing, Probability Distribution, Slope Stability