scholarly journals A Parametric Study of Blast Damage on Hard Rock Pillar Strength

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1901 ◽  
Author(s):  
Kashi Jessu ◽  
Anthony Spearing ◽  
Mostafa Sharifzadeh
Keyword(s):  
Parametric Study ◽  
Hard Rock ◽  
Numerical Models ◽  
Underground Mines ◽  
Pillar Stability ◽  
Pillar Strength ◽  
Blast Damage ◽  
Rock Pillars ◽  
Economic Standpoint ◽  
Safe Working

Pillar stability is an important factor for safe working and from an economic standpoint in underground mines. This paper discusses the effect of blast damage on the strength of hard rock pillars using numerical models through a parametric study. The results indicate that blast damage has a significant impact on the strength of pillars with larger width-to-height (W/H) ratios. The blast damage causes softening of the rock at the pillar boundaries leading to the yielding of the pillars in brittle fashion beyond the blast damage zones. The models show that the decrease in pillar strength as a consequence of blasting is inversely correlated with increasing pillar height at a constant W/H ratio. Inclined pillars are less susceptible to blast damage, and the damage on the inclined sides has a greater impact on pillar strength than on the normal sides. A methodology to analyze the blast damage on hard rock pillars using FLAC3D is presented herein.

scholarly journals Finite Element Modeling and Parametric Study on Floor Steel Beam Concrete Slab System in Non-Composite Action.

2018 ◽  
Vol 24 (7) ◽  
pp. 95
Author(s):  
Salah R. Al-Zaidee ◽  
Ehab Ghazi Al-Hasany
Keyword(s):  
Finite Element ◽  
Friction Force ◽  
Parametric Study ◽  
Numerical Models ◽  
Concrete Slab ◽  
Linear Regression Analysis ◽  
Element Model ◽  
Steel Beam ◽  
Composite Action ◽  
Shear Connectors

This study aims to show, the strength of steel beam-concrete slab system without using shear connectors (known as a non-composite action), where the effect of the friction force between the concrete slab and the steel beam has been investigated, by using finite element simulation. The proposed finite element model has been verified based on comparison with an experimental work. Then, the model was adopted to study the system strength with a different steel beam and concrete slab profile. ABAQUS has been adopted in the preparation of all numerical models for this study. After validation of the numerical models, a parametric study was conducted, with linear and non-linear Regression analysis. An equation regarding the concrete slab-steel beam system strength in non-composite action has been pointed out. Where the actual strength of the beam without using shear connectors has been located in between the full composite action and non-composite action. However, partial-composite action has been noted, due to the effectiveness of friction force which makes the beam behave as composite before the slip occurs.  

Material Property Effects on Critical Buckling Strains in Energy Pipelines

2002 ◽  
Author(s):  
Alfred B. Dorey ◽  
David W. Murray ◽  
J. J. Roger Cheng
Keyword(s):  
Material Property ◽  
Parametric Study ◽  
Numerical Models ◽  
Local Buckling ◽  
Analytical Models ◽  
Basic Material ◽  
Line Pipe ◽  
Moment Capacity ◽  
Yield Plateau ◽  
Critical Buckling Strain

Investigations in the development of a predictive critical buckling strain equation have shown that the grade of the material is one of five fundamental non-dimensional parameters in determining the critical local buckling strain for line pipe under combined loads. Further to this, the shape of the material curve also plays a significant role in the resulting critical buckling strain. Over 50 full-scale test specimens have been tested at the University of Alberta and effective numerical finite element analytical models have been developed. A parametric study consisting of 170 analyses was performed using the numerical models and critical buckling strain equations were derived. One of the essential variables in the new equations is a function of the specimen’s material properties. The results indicate that the higher the grade of the material the lower the value of the critical buckling strain. Furthermore, the level of agreement between the new equations and the experimental data was found to be dependent on the shape of the material curve for the specimen. Experimentally, two basic material curve shapes were observed, namely: specimens with a “rounded” material curve through the yield strength and specimens with a material property that exhibited a distinct “yield plateau” or yield point. Comparison of the experimental and numeric data showed that the specimens that were fabricated from material with a distinct yield plateau had different critical buckling strains when compared to specimens tested with rounded material curves. A subsequent parametric study was undertaken to examine the effect that the different shaped material curves had on the local and global behaviour. The results of this subsidiary parametric study showed that the global moment capacity was essentially independent of the shape of the material curve (the ratio of the peak moment from the yield plateau material to the peak moment for the rounded material was 1.018). However, the local critical buckling strain was significantly lower for the specimens analyzed with the material that had the yield plateau (the ratio of the critical strains for the two different material curves was 0.710).

scholarly journals Predicting Hard Rock Pillar Stability Using GBDT, XGBoost, and LightGBM Algorithms

Mathematics ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 765 ◽  
Author(s):  
Weizhang Liang ◽  
Suizhi Luo ◽  
Guoyan Zhao ◽  
Hao Wu
Keyword(s):  
Large Scale ◽  
Prediction Models ◽  
Hard Rock ◽  
Gradient Boosting ◽  
Pillar Stability ◽  
Rock Pillar ◽  
Light Gradient ◽  
Gradient Boosting Machine ◽  
Extreme Gradient Boosting ◽  
Hard Rock Mines

Predicting pillar stability is a vital task in hard rock mines as pillar instability can cause large-scale collapse hazards. However, it is challenging because the pillar stability is affected by many factors. With the accumulation of pillar stability cases, machine learning (ML) has shown great potential to predict pillar stability. This study aims to predict hard rock pillar stability using gradient boosting decision tree (GBDT), extreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM) algorithms. First, 236 cases with five indicators were collected from seven hard rock mines. Afterwards, the hyperparameters of each model were tuned using a five-fold cross validation (CV) approach. Based on the optimal hyperparameters configuration, prediction models were constructed using training set (70% of the data). Finally, the test set (30% of the data) was adopted to evaluate the performance of each model. The precision, recall, and F1 indexes were utilized to analyze prediction results of each level, and the accuracy and their macro average values were used to assess the overall prediction performance. Based on the sensitivity analysis of indicators, the relative importance of each indicator was obtained. In addition, the safety factor approach and other ML algorithms were adopted as comparisons. The results showed that GBDT, XGBoost, and LightGBM algorithms achieved a better comprehensive performance, and their prediction accuracies were 0.8310, 0.8310, and 0.8169, respectively. The average pillar stress and ratio of pillar width to pillar height had the most important influences on prediction results. The proposed methodology can provide a reliable reference for pillar design and stability risk management.

Parametric study of direct filling system of medium-head navigation locks

2021 ◽  
Author(s):  
Tomáš Kašpar ◽  
Pavel Fošumpaur ◽  
Martin Králík ◽  
Milan Zukal
Keyword(s):  
Numerical Modeling ◽  
Parametric Study ◽  
Numerical Models ◽  
Filling Process ◽  
Filling System ◽  
Basic Parameters ◽  
1D Model ◽  
Using Data ◽  
Navigation Lock ◽  
The Impact

AbstractAs part of the research focusing on the safety of vessels during the lockage in navigation locks, two different 1D numerical modeling approaches were tested. These approaches are used to determine the force effects on vessels during the direct filling process of the navigation lock. These numerical models were verified using data measured on a physical model. Using the selected 1D model, a parametric study focusing on the impact of the basic parameters of the navigation lock including the lifting velocity of the gates on the maximum hawser forces was performed. The research has shown that with a suitable design of the upper gate, the direct filling system may also be used for medium-head navigation locks with a normal lift of up to 5 m.

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