scholarly journals Control Technology of Surface Movement Scope with Directional Hydraulic Fracturing Technology in Longwall Mining: A Case Study

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3480 ◽  
Author(s):  
Zhanjie Feng ◽  
Wenbing Guo ◽  
Feiya Xu ◽  
Daming Yang ◽  
Weiqiang Yang
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Longwall Mining ◽  
Numerical Models ◽  
Surface Subsidence ◽  
The Sustainable Development ◽  
Surface Movement ◽  
Directional Hydraulic Fracturing ◽  
Simulation Results ◽  
Overlying Strata

Mining-induced surface subsidence causes a series of environmental hazards and social problems, including farmland destruction, waterlogging and building damage in the subsidence area. To reduce mining damages, an innovative method of controlling the surface movement scope via artificial weak planes generated by hydraulic fracturing technology was proposed in this paper. Numerical models were built to analyze the influence of weak planes with different heights and dips on the overlying strata movement. The numerical simulation results showed that the weak planes structure cut off the development of the overlying strata displacement to the surface and affected the surface movement scope. When the weak planes’ dips were bigger than the angle of critical deformation, with the increase of the weak planes’ heights (0–120 m) the advance angle of influence changed from 53.61° to 59.15°, and the advance distance of influence changed from 173.31 m to 140.27 m which decreased by 30.04 m. In applications at Sihe coal mine in China, directional hydraulic fracturing technology was used in panel 5304 to form artificial weak planes in overlying strata. The measured surface subsidence and deformation value met the numerical simulation results and the mining-induced surface movement scope reduced. Moreover, no damage occurred to the surface buildings which were predicted to be in the affected area after extraction. This technology provided a new method to protect the surface structures from damages and had great benefits for the sustainable development of coal mines.

scholarly journals Fracture Mechanism in Overlying Strata during Longwall Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zhengyi Ti ◽  
Jiazhen Li ◽  
Meng Wang ◽  
Kang Wang ◽  
Zhupeng Jin ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fracture Mechanism ◽  
Longwall Mining ◽  
Flexural Rigidity ◽  
Central Area ◽  
Short Side ◽  
Wall Area ◽  
Key Stratum ◽  
Coal Wall ◽  
Overlying Strata

We used the key stratum theory to establish a more realistic thin-plate mechanical model of elastic foundation clamped boundary and study the fracture mechanism of overlying strata during longwall mining. We analyzed the fracture characteristics and factors affecting fracture of the key stratum combined with the Mohr–Coulomb yield criterion. Besides, we used numerical simulation methods to verify the evolution pattern of the overlying strata fracture. The results show that the fracture mechanisms of the elastic foundation clamped structure’s key stratum varied depending on the position under longwall mining. The advanced coal wall area of the upper surface is a compressive-shear fracture. The center area of the lower surface is a tensile fracture. With the increase of the excavation length and the load of the key stratum, the central area and the advanced coal wall area of the long side are fractured before the advanced coal wall area of the short side. With the increase of flexural rigidity of the key stratum, the advanced coal wall area of the long side fractures before the central area and the advanced coal wall area of the short side. With the increase of the foundation modulus and the advanced load of the key stratum, the central area fractures before the surrounding advanced coal wall area. The advanced influence distance was positively correlated with the key stratum’s flexural rigidity and advanced load and negatively correlated with the foundation modulus and excavation length. The advanced influence distance was not affected by the load of the key stratum. The numerical simulation results show that, with the increase of the mining area, the fracture trace of overlying strata in goaf extended to the coal wall’s interior. The fracture range of overlying strata is larger than that of the miningd: area. This study has a practical value for water disasters, gas outbursts, and rock strata control.

scholarly journals A Comprehensive Method for Subsidence Prediction on Two-Seam Longwall Mining

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3139 ◽  
Author(s):  
Bin Zhang ◽  
Jiacheng Ye ◽  
Zhongjian Zhang ◽  
Liang Xu ◽  
Nengxiong Xu
Keyword(s):  
Longwall Mining ◽  
Underground Mining ◽  
Surface Subsidence ◽  
Orthogonal Experimental Design ◽  
Parameter Inversion ◽  
Subsidence Prediction ◽  
Reliable Assessment ◽  
Seam Mining ◽  
Subsidence Monitoring ◽  
Overlying Strata

The purpose of mining subsidence prediction is to establish a reliable assessment for surface subsidence resulting from underground mining. In this study, a new method for predicting subsidence in two-seam mining is proposed. First, the surface subsidence due to mining the upper seam is monitored. Then, taking the subsidence data as indicators, the optimal mechanical parameters of overlying strata can be obtained by orthogonal experimental design and inverse analysis of numerical simulation. Finally, further subsidence is calculated and predicted by the numerical model. A case of two-seam underground mining is studied using this methodology. This coal mine is located in the Dongsheng coal field in Inner Mongolia, China. Based on GPS surface subsidence monitoring and parameter inversion, the subsidence induced by two-seam mining is estimated and predicted. This study shows that the ratio of the height of overlying strata to mining thickness (H/M), mining configuration and adjacent mining have a significant effect on the surface subsidence caused by two-seam mining. By parameter inversion, the proposed optimal parameters can be applied to predict the subsidence of a nearby mine with similar stratigraphic conditions. Furthermore, this methodology can also be used to predict the subsidence caused by mining of more than two seams.

Development of Design Technologies for Optimum Moonpool Shapes of Drill Ship

2007 ◽  
Author(s):  
Jong Jin Park ◽  
Mun Sung Kim ◽  
Hee Sung Lee ◽  
Young Kyu Ahn ◽  
Young Bok Kim ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Input Data ◽  
Three Dimensional ◽  
Ship Motions ◽  
Surface Movement ◽  
Seakeeping Analysis ◽  
Simulation Results ◽  
Six Degree Of Freedom ◽  
Rough Sea

The present study is concerned with the numerical and experimental analysis of a moonpool in rough sea. From hydrodynamic viewpoint, a moonpool of drill ships can cause various problems. Among them, two major problems arise such as an increased resistance and overflow on the deck due to pumping up phenomena. To overcome these inherit problems, we have carried out various numerical analysis to find optimum moonpool shapes. The three-dimensional numerical model adopting SOLA-VOF scheme is used to predict violent free surface movement inside of a moonpool due to irregular ship motions with six degree of freedom. For accurate input data of ship motions, a three dimensional panel method program is applied for seakeeping analysis. The resistance and seakeeping model test have been carried out at MARINE to validate the proposed moonpool shapes, which have been designed based on numerical simulation results.

Research on Numerical Simulation of Mining Subsidence

2011 ◽  
Vol 148-149 ◽  
pp. 384-387 ◽  
Author(s):  
Hong Ji ◽  
Xue Yi Yu
Keyword(s):  
Numerical Simulation ◽  
Mining Subsidence ◽  
Strip Mining ◽  
Mining Method ◽  
Surface Movement ◽  
Mining Conditions ◽  
The Law ◽  
Project Data ◽  
Mechanical Dynamics ◽  
Overlying Strata

The strip mining method is proposed to prohibit overlying strata and surface moving. The law of displacement and deformation damage of overlying strata and surface which is a sophisticated process of physical and mechanical dynamics is analyzed in theory. Based on the actual project data, the law is obtained by the numerical simulation with FLAC3D. Moreover, the strip reasonable mining method and interrelated parameters is presented according to the specific geology and mining conditions of coal. It is proved that the strip mining method can avoid geological damage effectively for overlying strata and surface movement in practice.

scholarly journals Numerical Study on Crack Propagation by Using Softening Model under Blasting

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Rong Hu ◽  
Zheming Zhu ◽  
Jun Xie ◽  
Dingjun Xiao
Keyword(s):  
Numerical Simulation ◽  
Crack Propagation ◽  
Numerical Study ◽  
Numerical Models ◽  
Incident Angle ◽  
Damage Model ◽  
Maximum Principal Stress ◽  
Stress Criterion ◽  
Proposed Model ◽  
Simulation Results

A mixed failure criterion, which combined the modified maximum principal stress criterion with the damage model of tensile crack softening, was developed to simulate crack propagation of rock under blasting loads. In order to validate the proposed model, a set of blasting models with a crack and a borehole with different incident angles with the crack were established. By using this model, the property of crack propagation was investigated. The linear equation of state (EOS) was used for rock, and the JWL EOS was applied to the explosive. In order to validate the numerical simulation results, experiments by using PMMA (polymethyl methacrylate) with a crack and a borehole were carried out. The charge structure and incident angle of the blasting experimental model were the same as those in the numerical models. The experiment results agree with the numerical simulation results.

scholarly journals Dynamic Finite Element Analysis of a New Type Flexible Rock Shed under the Impact of Rock Block and Improving the Design

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Lianming Cui ◽  
Min Wang ◽  
Tangrong Yu
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Impact Analysis ◽  
Numerical Models ◽  
Element Model ◽  
Functional Evaluation ◽  
Element Analysis ◽  
Simulation Results ◽  
Improved Design ◽  
The Impact

A 1:1 flexible rock shed made of flexible nets and steel-vaulted structure is manufactured and tested for functional evaluation with impact experiment previously. To further discuss the performance of this structure under the impact of rockfalls and to improve the design, numerical simulation for this structure is carried out in this paper. Firstly, the simplified numerical models for characterizing the mechanical behavior of the ring nets and wire meshes are deduced. Then, a detailed finite element model for the flexible rock shed is developed for impact analysis. By comparing the experimental data, the numerical model for the flexible rock shed is shown to be reliable in predicting the dynamic behavior of the flexible rock shed. Finally, combined with the numerical simulation results and experimental results, an improved design is presented, and the numerical simulation results show that the energy dispersion in the improved design of the rock shed is more equalized, and damages on the steel-vaulted structure are much improved.

scholarly journals Study of Characteristics of Surface Subsidence in Longwall Coal Mine under Poor Ground Conditions in Indonesia

2017 ◽  
Vol 6 (1) ◽  
pp. 129
Author(s):  
Phanthoudeth Pongpanya ◽  
Takashi Sasaoka ◽  
Hideki Shimada ◽  
Sugeng Wahyudi
Keyword(s):  
Numerical Simulation ◽  
Finite Difference ◽  
Coal Mine ◽  
Longwall Mining ◽  
Surface Subsidence ◽  
Maximum Surface ◽  
Mining Depth ◽  
Simulation Techniques ◽  
Ground Conditions ◽  
The Impact

This paper aims to study the characteristics of surface subsidence induced by longwall mining under poor ground conditions in Indonesia by means of numerical simulation techniques using finite difference code “FLAC3D”. The effect of mining depth in cases of single panel and multi-panel longwall mining, the influence of panel and pillar widths, and the impact of backfilling material, were incorporated into the FLAC3D software. The simulated results indicated that the angle of draw and maximum surface subsidence were significantly associated with the depth of mining, the number of extracted panels, the width of panel and pillar, and the type of backfill. In single panel mining, the largest maximum surface subsidence is observed in case of the shallowest mining depth, and it gradually decreases as the depth increases. In contrast, the angle of draw increases with increasing the mining depth. In multi-panel mining, the angle of draw and maximum surface subsidence increase as the mining depth increases. Moreover, the angle of draw and maximum surface subsidence decrease when the narrow panel and large pillar widths are adopted, and the backfilling materials are applied.

Avalanche Features in Silicon Schottky-FETs in Accordance with Numerical Simulation Results

2006 ◽  
Vol 65 (16) ◽  
pp. 1533-1546
Author(s):  
Yu. Ye. Gordienko ◽  
S. A. Zuev ◽  
V. V. Starostenko ◽  
V. Yu. Tereshchenko ◽  
A. A. Shadrin
Keyword(s):  
Numerical Simulation ◽  
Simulation Results

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

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