scholarly journals Improving the Numerical Modelling of In-Situ Rock Bolts Using Axial and Bending Strain Data from Instrumented Bolts

2022 ◽  
Author(s):  
Prasoon Singh ◽  
Hyongdoo Jang ◽  
A. J. S. Sam Spearing
Keyword(s):  
Numerical Modelling ◽  
Rock Bolt ◽  
Sensitivity Analyses ◽  
Rock Bolts ◽  
In Situ Data ◽  
Bending Strain ◽  
Data Source ◽  
Bolt Reinforcement ◽  
Reinforcement Design

AbstractNumerical modelling has become an important tool in the underground rock bolt reinforcement designing process. Numerical modelling provides the advantage of easily and quickly simulating complex underground geometries and mechanisms with sensitivity analyses. However, a numerical model needs to be calibrated using mathematical solutions, lab testing or with actual in-situ observations and measurements (which is the preferred method) before its results can be quantitatively applied to reinforcement design. Instrumented rock bolts provide a useful data source for calibrating in-situ rock bolt models. In this work, procedures have been presented to identify and determine the orientation of structures in the rock mass based on the strains on the instrumented rock bolts. A method to calibrate the rock bolt model with in-situ data is also presented. The results of the presented procedures have been validated with laboratory tests and numerical modelling. The procedures have been applied to create and calibrate an in-situ rock bolt model in FLAC3D and the results are validated using in-situ data.

scholarly journals NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL

2017 ◽  
Vol 57 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Jan Veselý
Keyword(s):  
Numerical Modelling ◽  
Plastic Material ◽  
Material Model ◽  
Small Strain ◽  
Theoretical Background ◽  
Linear Elastic ◽  
In Situ Data ◽  
Modified Cam Clay ◽  
Soil Behaviour

This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

scholarly journals Marine plastic debris in Indonesia: Baseline estimates (2010-2019) and monitoring strategies (2021-2025)

2020 ◽  
Vol 45 (2) ◽  
pp. 97-102
Author(s):  
Intan Suci Nurhati ◽  
Muhammad Reza Cordova
Keyword(s):  
Marine Debris ◽  
Plastic Debris ◽  
Debris Accumulation ◽  
In Situ Data ◽  
Monitoring Strategies ◽  
Level Model ◽  
Data Source ◽  
Baseline Values ◽  
Marine Plastic Debris

Indonesia set the mission to reduce marine plastic debris by 70% between 2018-2025 with a global significance to support the UN Sustainable Development Goal 14.1. This short communication assesses marine debris baseline estimates in Indonesia before 2020 from available contributions and provides recommendations for monitoring marine debris mitigation between 2021-2025. Widely ranging model estimates of plastic debris released into seas highlight the roles of data source, the spatial resolution of models, and in situ data to provide representative baseline values. Recognizing the strengths and uncertainties of available contributions, model outputs converge on a baseline value of 0.52 ± 0.36 million tons (Mt) per year prior to 2020 in Indonesia, therefore setting a targeted reduced number of 0.16 Mt of marine debris releases in 2025. The Indonesian Institute of Sciences showed a preliminary value of plastic debris accumulation in beaches at 113.58 ± 83.88 g/m2 monthly or equivalent to 0.40 Mt/year by assuming plastic debris is most pervasive within 3 meters from Indonesia’s 99,093 km-long coastlines. It is important to distinguish that while river monitoring data informs land-based plastic debris releases, stranded beach debris represents a fraction of debris that is not present in the water column and bottom sediments. Moving forward, monitoring initiatives to mitigate marine debris should leverage on nationwide municipality-level model estimates (e.g., the source to leakage route framework of the National Plastic Action Partnership) as well as in situ river and coastal particularly but not limited to sites co-identified in previous monitoring studies (i.e., Medan, Batam-Bintan, Padang, Jakarta-Seribu Islands, Semarang, Pontianak, Bali, Lombok, Makassar, Manado, Bitung). The latter should be conducted at least seasonally, considering evidence of monsoonal variations of marine debris release and accumulation in Indonesia. Indonesia's vastness and regional diversity require coordination among stakeholders (government agencies, research institutions, universities, NGOs, citizen scientists) to monitor progress in the environments.

scholarly journals Length Effect on Load Bearing Capacities of Friction Rock Bolts

2019 ◽  
Author(s):  
Eren Komurlu ◽  
Serhat Demir
Keyword(s):  
Numerical Modelling ◽  
Bearing Capacity ◽  
Experimental Studies ◽  
Rock Bolt ◽  
Rock Bolts ◽  
Length Effect ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Pull Out ◽  
Modelling Study

Change in the load bearing capacity of the split set type friction rock bolts with variations of bolt lengths was investigated within this study. To determine a relation between the load bearing capacity and bolt length parameters, different friction bolt models with various lengths were analyzed with a numerical modelling study. In addition, a series of pull-out tests was carried out to evaluate the load bearing capacities of the split set type friction rock bolts with different lengths. The load bearing capacity of the bolts was found to decreasingly increase with the increase in the bolt length. As an outcome of this study, a relation between the load bearing capacity and rock bolt length parameters is suggested in accordance with the results obtained from both numerical and experimental studies.

scholarly journals MODELLING ROCK MASS IMPROVEMENT USING ROCK BOLTS

2017 ◽  
Vol 10 ◽  
pp. 43 ◽  
Author(s):  
Jan Pruška
Keyword(s):  
Rock Mass ◽  
Rock Bolt ◽  
Numerical Calculations ◽  
Underground Excavation ◽  
Rock Bolts ◽  
Fem Modelling ◽  
Excavation Stability ◽  
Bolt Reinforcement ◽  
Grouted Bolts ◽  
Underground Constructions

Anchor support currently represents a significant reinforcing technique in underground constructions. The principles of rock bolt reinforcement action are derived from various concepts of the underground excavation stability. In recent times, rock bolt design techniques have been complemented by numerical calculations procedures. The paper describes FEM modelling of a rock bolt system for mechanical and grouted bolts.

STORM ICE OIL WIND WAVE WATCH SYSTEM (SIOWS): WEB GIS APPLICATION FOR MONITORING THE ARCTIC

2017 ◽  
Author(s):  
Alexander Myasoedov ◽  
Alexander Myasoedov ◽  
Sergey Azarov ◽  
Sergey Azarov ◽  
Ekaterina Balashova ◽  
...  
Keyword(s):  
Satellite Data ◽  
Wind Wave ◽  
Arctic Region ◽  
Web Gis ◽  
The Arctic ◽  
Flexible Tool ◽  
In Situ Data ◽  
Current State ◽  
Watch System

Working with satellite data, has long been an issue for users which has often prevented from a wider use of these data because of Volume, Access, Format and Data Combination. The purpose of the Storm Ice Oil Wind Wave Watch System (SIOWS) developed at Satellite Oceanography Laboratory (SOLab) is to solve the main issues encountered with satellite data and to provide users with a fast and flexible tool to select and extract data within massive archives that match exactly its needs or interest improving the efficiency of the monitoring system of geophysical conditions in the Arctic. SIOWS - is a Web GIS, designed to display various satellite, model and in situ data, it uses developed at SOLab storing, processing and visualization technologies for operational and archived data. It allows synergistic analysis of both historical data and monitoring of the current state and dynamics of the "ocean-atmosphere-cryosphere" system in the Arctic region, as well as Arctic system forecasting based on thermodynamic models with satellite data assimilation.

scholarly journals Critical Dynamics of Defects and Mechanisms of Damage-Failure Transitions in Fatigue

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2554
Author(s):  
Oleg Naimark ◽  
Vladimir Oborin ◽  
Mikhail Bannikov ◽  
Dmitry Ledon
Keyword(s):  
Fatigue Damage ◽  
Kinetic Equations ◽  
Experimental Methodology ◽  
Preliminary Deformation ◽  
Scaling Properties ◽  
In Situ Data ◽  
Number Of Cycles ◽  
Fish Eye ◽  
Very High

An experimental methodology was developed for estimating a very high cycle fatigue (VHCF) life of the aluminum alloy AMG-6 subjected to preliminary deformation. The analysis of fatigue damage staging is based on the measurement of elastic modulus decrement according to “in situ” data of nonlinear dynamics of free-end specimen vibrations at the VHCF test. The correlation of fatigue damage staging and fracture surface morphology was studied to establish the scaling properties and kinetic equations for damage localization, “fish-eye” nucleation, and transition to the Paris crack kinetics. These equations, based on empirical parameters related to the structure of the material, allows us to estimate the number of cycles for the nucleation and advance of fatigue crack.

scholarly journals Measuring and inferring the ice thickness distribution of four glaciers in the Tien Shan, Kyrgyzstan

2020 ◽  
pp. 1-18
Author(s):  
Lander Van Tricht ◽  
Philippe Huybrechts ◽  
Jonas Van Breedam ◽  
Johannes J. Fürst ◽  
Oleg Rybak ◽  
...  
Keyword(s):  
Cross Validation ◽  
Thickness Distribution ◽  
Tien Shan ◽  
Ice Thickness ◽  
Ice Volume ◽  
In Situ Data ◽  
Radio Echo Sounding ◽  
Thickness Measurements ◽  
Tien Shan Mountains

Abstract Glaciers in the Tien Shan mountains contribute considerably to the fresh water used for irrigation, households and energy supply in the dry lowland areas of Kyrgyzstan and its neighbouring countries. To date, reconstructions of the current ice volume and ice thickness distribution remain scarce, and accurate data are largely lacking at the local scale. Here, we present a detailed ice thickness distribution of Ashu-Tor, Bordu, Golubin and Kara-Batkak glaciers derived from radio-echo sounding measurements and modelling. All the ice thickness measurements are used to calibrate three individual models to estimate the ice thickness in inaccessible areas. A cross-validation between modelled and measured ice thickness for a subset of the data is performed to attribute a weight to every model and to assemble a final composite ice thickness distribution for every glacier. Results reveal the thickest ice on Ashu-Tor glacier with values up to 201 ± 12 m. The ice thickness measurements and distributions are also compared with estimates composed without the use of in situ data. These estimates approach the total ice volume well, but local ice thicknesses vary substantially.

scholarly journals Studying the performance of fully encapsulated rock bolts with modified structural elements

2021 ◽  
Author(s):  
Jianhang Chen ◽  
Hongbao Zhao ◽  
Fulian He ◽  
Junwen Zhang ◽  
Kangming Tao
Keyword(s):  
Shear Stress ◽  
Load Transfer ◽  
Maximum Shear Stress ◽  
Coupling Model ◽  
Numerical Approach ◽  
Rock Bolt ◽  
Structural Elements ◽  
Rock Bolts ◽  
Two Stage ◽  
Bolt Diameter

AbstractNumerical simulation is a useful tool in investigating the loading performance of rock bolts. The cable structural elements (cableSELs) in FLAC3D are commonly adopted to simulate rock bolts to solve geotechnical issues. In this study, the bonding performance of the interface between the rock bolt and the grout material was simulated with a two-stage shearing coupling model. Furthermore, the FISH language was used to incorporate this two-stage shear coupling model into FLAC3D to modify the current cableSELs. Comparison was performed between numerical and experimental results to confirm that the numerical approach can properly simulate the loading performance of rock bolts. Based on the modified cableSELs, the influence of the bolt diameter on the performance of rock bolts and the shear stress propagation along the interface between the bolt and the grout were studied. The simulation results indicated that the load transfer capacity of rock bolts rose with the rock bolt diameter apparently. With the bolt diameter increasing, the performance of the rock bolting system was likely to change from the ductile behaviour to the brittle behaviour. Moreover, after the rock bolt was loaded, the position where the maximum shear stress occurred was variable. Specifically, with the continuous loading, it shifted from the rock bolt loaded end to the other end.

scholarly journals Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

2016 ◽  
Vol 16 (14) ◽  
pp. 9435-9455 ◽  
Author(s):  
Matthew J. Alvarado ◽  
Chantelle R. Lonsdale ◽  
Helen L. Macintyre ◽  
Huisheng Bian ◽  
Mian Chin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Size Distribution ◽  
Visible Radiation ◽  
Submicron Aerosol ◽  
In Situ Data ◽  
Aerosol Absorption ◽  
Aerosol Scattering ◽  
The Impact

Abstract. Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10–23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction throughout the aerosol size distribution. Using a core-shell mixing rule in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for modeling the time-varying mixing states of aerosols in future versions of ASP.

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