scholarly journals Displacement Measurements and Numerical Analysis of Long-Term Rock Slope Deformation at Higashi-Shikagoe Limestone Quarry, Japan

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Clement A. Amagu ◽  
Cheng Zhang ◽  
Jun-ichi Kodama ◽  
Kazuyuki Shioya ◽  
Tomoyuki Yamaguchi ◽  
...  
Keyword(s):  
Slope Failure ◽  
Rock Slope ◽  
Shear Failure ◽  
Surface Displacement ◽  
Slope Deformation ◽  
Open Pit ◽  
Foot Wall ◽  
Limestone Quarry ◽  
Right Hand ◽  
Left And Right

The Higashi-Shikagoe limestone quarry is an open-pit mine situated in Hokkaido Prefecture, Japan, that has experienced four slope failure incidents since 1996. The rock slope behaviour has been monitored since the first failure event by measuring the rock slope surface displacement using an automated polar system. Recent measurements have revealed a gradual decrease of the distance between the beam generator and mirrors over time; however, the displacements and decrease rate differs between the centre and left- and right-hand sides of the quarry. This implies that the deformation characteristics of the rock slope and factors influencing the slope deformation differ at the centre and left- and right-hand sides of the quarry. In this study, the two-dimensional finite element method was used to identify the causes of slope deformation by investigating the effects of limestone excavation at the foot of the rock slope, the deterioration of a ∼70 m-thick clay layer at the rock slope foot wall, and shear failure owing to rainfall infiltration. The numerical results show that slope deformation on the left-hand side and centre of the quarry are induced by clay deterioration, whereas the right-hand side of the quarry is deformed owing to floor excavation and/or shear sliding. The rock slope is presently stable because the magnitude of the rate of displacement decrease is small and no acceleration is observed.

scholarly journals STABILITY ANALYSIS AND FAILURE MECHANISMS OF OPEN PIT ROCK SLOPE

2017 ◽  
Vol 2 (3) ◽  
pp. 255
Author(s):  
Yahdi Azzuhry
Keyword(s):  
Rock Mass ◽  
Class Number ◽  
Kinematic Analysis ◽  
Slope Failure ◽  
Rock Slope ◽  
Failure Mechanisms ◽  
Slope Angle ◽  
Open Pit ◽  
Wedge Failure ◽  
Planar Failure

Rock mass in nature tend to be unideal, for it is heterogeneous, anisotropic and has discontinuity. The discontinuity makes anisotropic strength and stress in the rock mass, and also controls the changing of the elastic properties of rock mass. This condition results to disruptions in the rock mass strength balance, and finally drives the slopes to collapse. This study aims to determine the slope failure mechanisms in the area of case study, as well as its variations based on the Rock Mass Rating (RMR), Geological Strength Index (GSI), Slope Mass Rating (SMR), kinematic analysis, numerical analysis and monitoring approach slope movement in a coal mine slope applications. The site investigations were implemented to obtain information about slope collapse. Prior to the collapse, the slope inclination was 38° with of 94 meters height, strike slope of N 245 E and direction of slope surface of 335°. After the collapse, the slope was became 25º; and after the collapse materials were cleared, it was 35º. The discontinuity mapping obtained 5 sets of discontinuities, and the data were developed to obtain the value of RMR. The result of piezometer measurements was that at occurrence of collapse, slope elevation was 44.40m. Displacement value from monitoring SSMR showed that when the slope was collapsing in two stages, the first stage value was 70.61cm (a more critical condition, the value was rounded down to 70cm to the implementation in modelling) and the second stage value was at 124.25cm. The value of RMR89 in this study was greater than the value of GSI and SMR. As for the average value, it was obtained 34.67 for RMR89 value and 29.67 for GSI value, these rocks then can be classified into Poor Rock class number IV. The result of kinematic analysis found that sliding planar failure at dips 36°, and wedge failure at dips 36°, 35° and 34°. Acquisition SMR value obtained at 25, 27, 28 and 29. The SMR values classified the rock mass quality into class number IV, the description of the rock mass was relatively poor, the slope stability was low or unstable and the collapse manifold was planar or wedge failure. The result from the analysis of the model with its criteria obtained was that un-collapse conditions at angle 29°. It is recommended to use 29° angle to repair the slopes, and also recommended for overall high wall slope angle. Type of collapse that occurred on the slope failure mechanisms in all of the analysis that has been done, it is known that the mechanisms involved are complex types (combine of wedge failure, planar failure, and step-path failure) or classified into large scale rock slope failure surface.

scholarly journals A temperature- and stress-controlled failure criterion for ice-filled permafrost rock joints

2018 ◽  
Author(s):  
Philipp Mamot ◽  
Samuel Weber ◽  
Tanja Schröder ◽  
Michael Krautblatter
Keyword(s):  
Failure Criterion ◽  
Slope Failure ◽  
Rock Slope ◽  
Shear Failure ◽  
Shear Resistance ◽  
Stress Conditions ◽  
Rock Joints ◽  
Normal Stresses ◽  
Permafrost Rock ◽  
Limestone Sample

Abstract. Instability and failure of permafrost-affected rock slopes have significantly increased coincident to warming in the last decades. Most of the observed failures in permafrost-affected rock walls are likely triggered by the mechanical destabilisation of warming bedrock permafrost including effects in ice-filled joints. The failure of ice-filled rock joints has only been observed in a small number of experiments, often using concrete as a rock analogue. Here, we present a systematic study of the brittle shear failure of ice and rock-ice interfaces, simulating the accelerating phase of rock slope failure. For this, we performed 141 shear experiments with rock-ice-rock sandwich samples at constant strain rates provoking ice fracturing (10−3 s−1), under relevant stress conditions ranging from 100 to 800 kPa, i.e. 4–30 m rock overburden, and at temperatures from −10 to −0.5 °C, typical for recent rock slope failures in alpine permafrost. To create close to natural but reproducible conditions, limestone sample surfaces were ground to international rock mechanical standard roughness. Acoustic emission (AE) was successfully applied to describe the fracturing behaviour, anticipating rock-ice failure as all failures are predated by an AE hit increase with peaks immediately prior to failure. We demonstrate that both, the warming and unloading (i.e. reduced overburden) of ice-filled rock joints lead to a significant drop in shear resistance. With a temperature increase from −10 °C to −0.5 °C, the shear stress at failure reduces by 64–78 % for normal stresses of 100–400 kPa. At a given temperature, the shear resistance of rock-ice interfaces decreases with decreasing normal stress. This can lead to a self-enforced rock slope failure propagation: as soon as a first slab has detached, further slabs become unstable through progressive thermal propagation and possibly even faster by unloading. Here, we introduce a new Mohr-Coulomb failure criterion for ice-filled rock joints that is valid for joint surfaces which we assume similar for all rock types, and which applies to temperatures from −8 to −0.5 °C and normal stresses from 100 to 400 kPa. It contains a temperature-dependent friction and cohesion which decrease by 12 %/°C and 10 %/°C respectively due to warming and it applies to temperature and stress conditions of more than 90 % of the recently documented accelerating failure phases in permafrost rock walls.

scholarly journals Rock slope discontinuity extraction from 3D point clouds: Application to an open pit limestone quarry

Warta Geologi ◽  
2020 ◽  
Vol 46 (2) ◽  
pp. 107-112
Author(s):  
Syaran Suri ◽  
◽  
Aisyah Shahirah Juhari ◽  
Solihin Yaacob ◽  
Nur Emilia Qistina Anua ◽  
...  
Keyword(s):  
Rock Slope ◽  
Point Clouds ◽  
Open Pit ◽  
Limestone Quarry ◽  
3D Point Clouds ◽  
Slope Discontinuity

Visual context differentially mediates left- and right-hand reaching movements

2009 ◽  
Author(s):  
Jos J. Adam ◽  
Susan Hoonhorst ◽  
Rick Muskens ◽  
Jay Pratt ◽  
Martin H. Fischer
Keyword(s):  
Reaching Movements ◽  
Visual Context ◽  
Right Hand ◽  
Left And Right
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