scholarly journals Slope mass rating-based analysis to assess rockfall hazard on Yogyakarta Southern Mountain, Indonesia

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Karlina Triana ◽  
Koko Hermawan
2020 ◽  
Author(s):  
Karlina Triana ◽  
Koko Hermawan

Abstract The main road to the Parangtritis Beach tourism site in the southern Yogyakarta Province, Indonesia, has full of local and economic activities. The road was made mainly by karst mountains cutting and resulting in almost vertical long and high slopes by its side. Rockfall is being the most potential hazards occurred in this area. The purpose of this study is to determine the rockfalls hazard assessment along the main road using Slope Mass Rating (SMR) analysis. Parameters used in rockfall hazard assessment are SMR with additional valuation from the slope height and the block size. The necessary data of each parameter obtained by direct measurement and the uniaxial compressive strength test in the laboratory. Geomechanics analysis, stereographic projection analysis, and hazard parameters weighting are needed to produce research results in form Rockfall Hazard Zonation Map in the research location. The results showed that the largest percentage of rockfalls hazard class is very low class, with 83,83% of the total hazard classes, associated with normal SMR score (51,66 – 51,75), slope height between 2,85 – 4,57 m, and block size 0,2 – 0,3 m. Followed by intermediate class with 7,16% of the total hazard classes with very bad to bad SMR score (5,82 – 38,15), slope height between 4,26 – 8,96 m, and block size 0,3 – 1,0 m. In the third position followed by a low class with 4,28% of the total hazard classes with bad to normal SMR score (31,17 – 53,03), slope height between 3,52 – 5,28 m, and block size 0,2 – 0,7 m. The last position was taken by high class with 4,19% of the total hazard classes with very bad to bad SMR score (18,31 – 36,50), slope height between 3,62 – 7,82 m, and block size 0,7 – 1,3 m. The SMR analysis also identified the influence of rock types with the rockfall occurrence. Hazard zonation map verification showed a congeniality with the results of rockfalls quantity inventory in the research area.


2020 ◽  
Author(s):  
Karlina Triana ◽  
Koko Hermawan

Abstract In the Parangtritis Beach tourism area located in the Southern Mountain of Yogyakarta, karst hills were excavated to build the main accessing road and produce some of long and very steep slopes along the sides of the road. But still, there was none of the slope reinforcement installed along the road. Meanwhile, at several nearby locations within Southern Mountain, rockfall incidents have occurred many times even caused casualties. The potential of rockfall hazard could also occur in the main road of Parangtritis Beach as the study area. The purpose of this study is to determine the rockfall hazard assessment along the main road using Slope Mass Rating (SMR) analysis with the additional parameter of the slope height and the rock block size. The necessary data obtained by direct measurement and laboratory test. Geomechanics analysis, stereographic projection analysis, and hazard parameters weighting were carried out to produce the Rockfall Hazard Zonation Map of the study area. Based on 17 measurement stations, there are 4 (four) rockfall hazard classes in the study area, i.e. very low, low, intermediate, and high. The very low class, which also included road segments without slope, has the largest percentage of 83.83%, followed by the classes of intermediate, low, and high with the percentage of 7.16%, 4.28%, and 4,19%, respectively. SMR was assumed as the most significant parameter that influences the rockfall hazard zonation. To validate the predicted hazard zones, historical rockfall points were overlaid over the Rockfall Hazard Zonation Map. Since 91.23% of the rockfall occurred in the intermediate and high hazard classes, the zonation can be considered reliable to predict future rockfall. This study also identified several landslide potential zones and provides the recommendation of slope reinforcement to be installed in the study area.


2020 ◽  
Author(s):  
Karlina Triana ◽  
Koko Hermawan

Abstract In the Parangtritis Beach tourism area located in the Southern Mountain of Yogyakarta, karst hills were excavated to build the main accessing road and produce some of long and very steep slopes along the sides of the road. But still, there was none of the slope reinforcement installed along the road. Meanwhile, at several nearby locations within Southern Mountain, rockfall incidents have occurred many times even caused casualties. The potential of rockfall hazard also could be found in the main road of Parangtritis Beach as the study area. The purpose of this study is to determine the rockfall hazard assessment along the main road using Slope Mass Rating (SMR) analysis with the additional parameter of the slope height and the rock block size. The necessary data obtained by direct measurement and laboratory test. Geomechanics analysis, stereographic projection analysis, and hazard parameters weighting were carried out to produce the Rockfall Hazard Zonation Map of the study area. Based on 17 measurement stations, there are 4 (four) rockfall hazard classes in the study area, i.e., very low, low, moderate, and high. The class of very low, which also included road segments without slope, has the largest percentages of 83.83%, followed by the classes of moderate, low, and high with the percentage of 7.16%, 4.28%, and 4,19%, respectively. SMR was assumed as the most significant parameter that influences the rockfall hazard zonation. Historical rockfall points were overlaid over the Rockfall Hazard Zonation Map to validate the predicted hazard zones. Since 91.23% of the rockfall occurred in the moderate and high hazard classes, the zonation map considered reliable to predict future rockfall. This study also identified several landslide potential zones and provides the recommendation of slope reinforcement to be installed in the study area. Keywords: Rockfall, Slope Mass Rating, Hazard zonation, Slope reinforcement, Hills.


2016 ◽  
Vol 12 (4) ◽  
Author(s):  
Ari Sandyavitri

This paper objectives are to; (i) identification of risky slopes (within 4 Provinces in Sumatra including Provinces of Riau, West Sumatra, Jambi and South Sumatra encompassing 840 kms of the “Jalan Lintas Sumatra” highway) based on Rockfall Hazard Rating Systems (RHRS) method; (ii) developing alternatives to stabilize slope hazards, and (iii) selecting appropriate slopes stabilization techniques based on both proactive approach and value engineering one. Based on the Rockfall Hazard Rating Systems (RHRS) method, it was identified 109 steep slopes prone to failure within this highway section. Approximately, 15 slopes were identified as potential high-risk slopes (RHRS scores were calculated >200 points). Based on the proactive approach, seven riskiest slopes ware identified. The preferred stabilization alternatives to remedy most of these slopes are suggested as follow; either (i) a combination of retaining wall and drainage, or (ii) gabion structure and drainage. However, different approaches may yield different results, there are at least 2 main consideration in prioritizing slope stabilization; (i) based on the riskiest slopes, and(ii) the least expensive stabilization alternatives.


Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 158
Author(s):  
Didier Hantz ◽  
Jordi Corominas ◽  
Giovanni B. Crosta ◽  
Michel Jaboyedoff

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit as possible and describes methods to derive some of the main hazards and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized and diffuse hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed, and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the reach probability, and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (passage frequency) can be derived. This frequency is relevant for risk assessment when the element at risk can be damaged several times. If it is not replaced, the probability that it is impacted by at least one rockfall is more relevant.


2021 ◽  
Author(s):  
Vincent Acary ◽  
Franck Bourrier ◽  
David Toe ◽  
Francois Kneib

<p><br>Block propagation models are routinely used for the quantitative assessment of rockfall hazard. In these models, one of the major difficulties is the development of physically consistent and field applicable approaches to model the interaction between the block and the natural terrain. For most of propagation models, a thorough calibration of the input parameters is not available over the wide range of configurations encountered in practice. Consequently, the parameters choice is strongly depending on expert knowledge. In addition, most of models exhibit substantial sensitivity to some parameters, i.e. small changes of these parameters entail large differences in the simulation results.</p><p>The trajectory analysis platform Platrock, freely available upon request (contact: [email protected]), allows performing 2D and 3D simulations using both material point rebound models and models, based on non-smooth mechanics, that explicitly account for block shape. This platform provides several simulation tools for detailed analyses of block propagation on study sites.</p><p>The possibilities of the predictive capabilities of different block propagation modelling approaches integrated into the Platrock platform have been assessed on a well-documented study site, where a benchmark of propagation models has been done in the context of C2ROP research project. This analysis emphasized the capacities of trajectory analyses to traduce block propagation but also demonstrated their substantial sensitivity to model parameters. The results from these simulations cannot be relevantly interpreted if they are not accompanied with calibration proofs, sensitivity analysis, and detailed interpretation of the results from the expert in charge of the study.</p>


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