scholarly journals Three-dimensional Numerical Modeling Encompassing the Stability of a Vertical Gas Well Subjected to Longwall Mining Operation - A Case Study

2018 ◽  
Author(s):  
Bonaventura Alves Mangu Bali
Keyword(s):  
Numerical Modeling ◽  
Longwall Mining ◽  
Three Dimensional ◽  
Mining Operation ◽  
Gas Well ◽  
The Stability

scholarly journals Calibration of a Three-dimensional slope stability evaluation in Brazilian iron open pit mine

2021 ◽  
Author(s):  
Vidal Félix Navarro Torres ◽  
Rodrigo Dockendorff ◽  
Juan Manuel Girao Sotomayor ◽  
Cristian Castro ◽  
Aristotelina Ferreira da Silva
Keyword(s):  
Three Dimensional ◽  
Structural Features ◽  
Open Pit ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Strength Parameters ◽  
Dimensional Section ◽  
The Stability ◽  
Evaluation Techniques

Abstract It has historically been frequent among geotechnical practitioners, that the stability analysis of the slopes of an open pit is performed using a two dimensional section representing the highest and steepest walls within a certain geological setting. However, the literature shows that to predict rupture events in an open pit, a three-dimensional analysis would better represent the actual conditions, as the spatial distribution of the lithology and the structural features play an important role when defining the stability of the slopes. This paper presents the case study of an open it located in Brazil, which experienced instabilities between the years 2001-2019. An evaluation of the behavior of the open pit was performed by calibrating the strength parameters to represent the best documented rupture events. The three-dimensional model was made using the FLAC3D software. The results show that there is a good correlation between the results of the model and the reports of past instabilities. Finally, recommendations are presented for the inter-ramp angles for each lithology based on the calibrated stability analyzes performed. This work seeks to contribute to the knowledge in evaluation techniques for the three-dimensional behavior of open pits.

scholarly journals Numerical Analysis of the Width Design of a Protective Pillar in High-Stress Roadway: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
FuZhou Qi ◽  
ZhanGuo Ma ◽  
Ning Li ◽  
Bin Li ◽  
Zhiliu Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Energy Density ◽  
Large Deformation ◽  
High Stress ◽  
Vertical Stress ◽  
Pillar Width ◽  
Modeling Approach ◽  
Roadway Stability ◽  
The Stability

The width design of protective pillars is an important factor affecting the stability of high-stress roadways. In this study, a novel numerical modeling approach was developed to investigate the relationship between protective pillar width and roadway stability. With the 20 m protective pillar width adopted in the field test, large deformation of roadways and serious damage to surrounding rocks occurred. According to the case study at the Wangzhuang coal mine in China, the stress changes and energy density distribution characteristics in protective pillars with various widths were analysed by numerical simulation. The modeling results indicate that, with a 20 m wide protective pillar, the peak vertical stress and energy density in the pillar are 18.5 MPa and 563.7 kJ/m3, respectively. The phenomena of stress concentration and energy accumulation were clearly observed in the simulation results, and the roadway is in a state of high stress. Under the condition of a 10 m wide protective pillar, the peak vertical stress and energy density are shifted from the pillar to roadway virgin coal region, with peak values of 9.5 MPa and 208.3 kJ/m3, respectively. The decrease in vertical stress and energy density improves the stability of the protective pillar, resulting in the roadway being in a state of low stress. Field monitoring suggested that the proposed 10 m protective pillar width can effectively control the large deformation of the surrounding rock and reduce coal bump risk. The novel numerical modeling approach and design principle of protective pillars presented in this paper can provide useful references for application in similar coal mines.

scholarly journals Three Dimensional Epidemic Model with Non-monotonic Incidence and Saturated Treatment: A Case Study of SARS Infection of Hong Kong 2003 Scenario

2021 ◽  
Author(s):  
Uttam Ghosh ◽  
Susmita Sarkar ◽  
Jayanta Kumar Ghosh
Keyword(s):  
Hong Kong ◽  
Three Dimensional ◽  
Threshold Value ◽  
Effective Parameters ◽  
Cure Rate ◽  
The Stability ◽  
Necessary And Sufficient ◽  
Saturated Treatment ◽  
Disease Free

Abstract In this paper, we have proposed a mathematical compartmental model with non-monotonic incidence and saturated treatment and we have validated the model with SARS infection in Hong Kong, 2003. We have analysed the stability of disease free and endemic equilibria as well as different bifurcations. We have shown that the epidemic disappears if the cure rate of treatment crosses a threshold value. We have obtained a necessary and sufficient condition for backward bifurcation, which shows the basic reproduction number less than unity is not sufficient to eradicate the disease completely. Saddle-node and Hopf bifurcation with respect to awareness factor have been investigated, which shows that the awareness factor is effective to change the disease dynamics. The model has been fitted to SARS cases in Hong Kong. The most effective parameters for controlling infections have been identified through sensitivity analysis. Moreover, we have investigated how the number of infected cases reduces if there was some vaccination polices in SARS infection. Finally, the model has been also used as an optimal control problem as vaccination and treatment controls are time dependent functions.

Numerical Modeling of Soil-Pipeline Interaction Mechanism Caused by Surface Subsidence due to Longwall Mining

2013 ◽  
Vol 838-841 ◽  
pp. 2202-2207
Author(s):  
Guo Ming Cheng ◽  
Wen Jie Xu ◽  
Hong Bin Chu
Keyword(s):  
Numerical Modeling ◽  
Cross Sections ◽  
Longwall Mining ◽  
Measurement Data ◽  
Interaction Mechanism ◽  
Surface Subsidence ◽  
Face Advance ◽  
Subsidence Basin ◽  
The Face

In China, Surface subsidence caused by underground coal mining has affected the safe operation of pipelines in recent years. Take the coal mine in Shanxi section of the west-east gas pipeline as case study, numerical modeling was adopted to study the interaction mechanism of the soil-pipeline caused by longwall mining, and the numerical model was calibrated with the measurement data. The results reveal that the soil-pipeline interaction undergoes an evolution process from synchronization to separation during the subsidence process. The peak stresses on the pipeline at cross-sections occur generally above the centre of the corresponding subsidence basins at different stages of face advance, and the maximum stress on the pipeline appeared at about 150m above the centre of the subsidence basin as the face advances 300m.

Buckling Analysis of Pile during Hammer Placement

2012 ◽  
Vol 256-259 ◽  
pp. 467-470
Author(s):  
Shao Zeng Guo ◽  
Run Liu
Keyword(s):  
Finite Element ◽  
Geometric Nonlinearity ◽  
Large Diameter ◽  
Three Dimensional ◽  
Element Model ◽  
Offshore Engineering ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Three Dimensional Finite Element

Large diameter and thin thickness are the main characteristics of the steel pipe piles in offshore engineering. Before piling a pile, heavy hammer will be placed on the top of it, which may emerge a serious risk in pile buckling. A three dimensional finite element model of pile and soil was established for a case study. The modified Riks method which can automatically search a suitable increment factor of loads is adopted to assess the stability of the pile, and the geometric nonlinearity and pile-soil interaction were both considered. The practical example shows that the critical load considering pile-soil interaction is much smaller than that in a fixed constraint.

scholarly journals A Study on the Impact of Longwall-Mining Operation on the Stability of a Slope-Pillar Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wenyong Bai ◽  
Jie Zhang ◽  
Bin Wang ◽  
Jianchen Zhang ◽  
Hongru Li ◽  
...  
Keyword(s):  
Structural Model ◽  
Longwall Mining ◽  
Movement Pattern ◽  
Mining Operation ◽  
Mining Operations ◽  
Working Face ◽  
The Stability ◽  
Pillar Structure ◽  
Boundary Width ◽  
The Impact

The slope-pillar structure is defined as an artificial construction shaped by a surface highwall mining and an underground longwall mining. In order to study the impact of stress variations (induced by the longwall-mining operations) on the stability of a slope-pillar structure, No. 30101-1 working face of Nanliang Coal Mine was selected as the study subject. A series of analysis including physical similar simulation test and the theoretical analysis were conducted to study the movement pattern of the overlying strata in the working face of the slope and the loading and the stability of the pillar column revealing the mechanism of dynamic load instability of nonuniformly distributed load “slope pillar.” A “slope-pillar” reverse sliding structural model was proposed along with a newly established “slope-pillar” structural mechanical model and a formula to calculate the boundary width of the protection for the pillar under the extreme balance conditions. According to the study, the width of the protective pillar is designed at 20 m, and the roadway deformation during the working face and the stability of the pillar can satisfy the safety requirement concerning the working face, which further validates the theoretic deduction formula.

scholarly journals Three-Dimensional Analysis of Gate-Entry Stability in Multiple Seams Longwall Coal Mine Under Weak Rock Conditions

2020 ◽  
Vol 9 (1) ◽  
pp. 72
Author(s):  
Pisith Mao ◽  
Hideki Shimada ◽  
Akihiro Hamanaka ◽  
Sugeng Wahyudi ◽  
Jiro Oya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Coal Mine ◽  
Longwall Mining ◽  
Three Dimensional ◽  
Weak Rock ◽  
Failure Zone ◽  
East Kalimantan ◽  
The Stability ◽  
Coal Reserves

A study of multiple seams longwall mining is proposed to investigate its applicability in Indonesia coal mine. The study area of this research is PT Gerbang Daya Mandiri (GDM) coal mine located in East Kalimantan Island. The study of seam interaction is crucial for developing multiple seams longwall mining especially when it comes to weak rock conditions which are usually found in most of the coal reserves in Indonesia. This paper will use numerical simulation to investigate the effect of the first mined-out seam on the development of the second coal seam gate-entry by considering a couple of key parameters including depth of the coal seam and interburden length. The simulation model consists of two main indicators for instability which include failure zone, the contour of safety factor. The results show that the effect of seam interaction on gate-entry has different intensity based on the thickness of the interburden and coal seam depth. This work also provided appropriate support configuration for maintaining the stability of gate-entry.

scholarly journals Analysis of support system for a conveyance tunnel in the higher Himalayan zone: A case study on Upper Tamakoshi HEP, Nepal

2021 ◽  
Vol 4 (1) ◽  
pp. 90-97
Author(s):  
Kalyan Paudyal
Keyword(s):  
Numerical Modeling ◽  
Stress Concentration ◽  
Support System ◽  
Empirical Method ◽  
Vital Role ◽  
Site Specific ◽  
Specific Data ◽  
Overburden Thickness ◽  
The Stability

After excavation, insitu stress conditions are changed which lead deformation due to the stress concentration. For the stability in the excavated tunnel profile, appropriate support system is essential. To recommend the support system, site specific data are used from Higher Himalayan Region of Nepal. Study is focused on 3 m and 6 m size inverted D Shaped tunnel with three different overburden thickness. For the analysis of support system: Empirical method, Analytical method and Numerical Modeling are performed. Result obtained from the different approaches for three different overburden heights as well as for both size tunnels are compared and finally required support system is recommended. It was found significant change in deformations while increase in size of tunnel. Overburden thickness is also playing the vital role in this parameter but size effect is more prominent.

A Physical and Numerical Modeling for Launching of Jackets (Case Study on Balal PLQ Platform)

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
M. R. Honarvar ◽  
Moharam D. Pirooz ◽  
Mohammad R. Bahaari
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Oil Field ◽  
Physical Models ◽  
Lower Viscosity ◽  
The Difference ◽  
The Stability ◽  
Stability Of Structures ◽  
Similarity Laws

Platform structures are commonly utilized for various purposes including offshore drilling, processing, and support of offshore operations. A jacket is a supporting structure for deck facilities, stabilized by piles driven through it to the seabed. In a jacket design, operational and environmental loads are very important and must be intensively investigated to secure the stability of structures during their service life, as well as installation phase. The main purpose of this research is to evaluate the results of physical modeling for the launch operation of jackets from barge into the sea, as the most hazardous stage in the installation of a platform, and compare them to those of numerical modeling. Both physical and numerical modeling parameters are described and they are examined on a prototype platform, i.e., Balal oil field production and living quarter platform that is a 1700 tone, eight-legged jacket located in the center of Persian Gulf, some 100km distance from Iranian Lavan Island. It is found that both numerical and physical methods can describe the motion of the barge similarly well, but some differences are traced in the motion of jacket. The inequalities are, then, appeared to be due to the Froude-type parameters applied for modeling purpose. One notable fact investigated in this research is the necessity for choosing Reynolds–Froude type in the physical modeling of the launch, instead of Froude type. This is because, in addition to the importance of gravitational and inertial forces, the viscosity affects the drag hydrodynamic force, as well. It should be noted that viscosity and consequently drag coefficient in Froude type modeling cannot be quite applicable and this causes the difference observed between the results of physical and numerical modeling. Although there have been so many jacket launching designed and probably their physical models have been tested, but to the best of our knowledge from the literature, there was found no study on Reynolds–Froude physical modeling of jacket launch phenomenon. If one is interested in practicing a Reynolds-Froude physical modeling, it could be done either in a centrifuge test or by using a fluid with lower viscosity dependent on the scale of model, or even by finding a fluid (with new viscosity and new density) and a new gravity to have simultaneously the Froude and the Reynolds similarity laws satisfied.

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