Characteristics of Transmission Radio Waves in Undulating Coal Seams and a Topographic Correction Method For Its Tomography

2021 ◽  
Author(s):  
Rongxin WU ◽  
Huanqi GU ◽  
zean hu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Radio Wave ◽  
Three Dimensional ◽  
Correction Method ◽  
Radio Waves ◽  
Validity And Reliability ◽  
Coal Seams ◽  
Simulation Experiments ◽  
Wave Tomography

Abstract The transparency of coal seam working face is an important assurance for safe and accurate mining of coal mines. Mine geophysical prospecting is an important means for geological exploration of coal seam working faces, among which the mine radio wave tomography is one of the most common and effective methods. However, the undulating feature of the coal seam will greatly interfere the high-precision attenuation electromagnetic wave imaging. Through two-dimensional numerical simulation experiments, we identified that in a horizontal coal seam, the energy of penetrated radio wave showed an approximate linear attenuation law, while in an inclined coal seam, it showed a very different parabolic attenuation trend. To eliminate the influence of coal seam inclination on the accuracy of radio wave tomography, in this paper, we proposed a correction method for imaging undulating coal seams using radio wave tomography. Further, through three-dimensional numerical simulation experiments, we verified the validity and reliability of the correction method. Overall, both theoretical and numerical simulation experiments indicated that the method could basically eliminate the influence of coal seam inclination and improve the imaging accuracy.

scholarly journals Surrounding Rock Movement of Steeply Dipping Coal Seam Using Backfill Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wenyu Lv ◽  
Kai Guo ◽  
Jianhao Yu ◽  
Xufeng Du ◽  
Kun Feng
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Surrounding Rock ◽  
Maximum Deflection ◽  
Coal Seams ◽  
Physical Similarity ◽  
Working Face ◽  
Rock Structure ◽  
Backfill Mining ◽  
The Stability

The movement of the overlying strata in steeply dipping coal seams is complex, and the deformation of roof rock beam is obvious. In general, the backfill mining method can improve the stability of the surrounding rock effectively. In this study, the 645 working face of the tested mine is used as a prototype to establish the mechanical model of the inclined roof beam using the sloping flexible shield support backfilling method in a steeply dipping coal seam, and the deflection equation is derived to obtain the roof damage structure and the maximum deflection position of the roof beam. Finally, numerical simulation and physical similarity simulation experiments are carried out to study the stability of the surrounding rock structure under backfilling mining in steeply dipping coal seams. The results show the following: (1) With the support of the gangue filling body, the inclined roof beam has smaller roof subsidence, and the maximum deflection position moves to the upper part of working face. (2) With the increase of the stope height, the stress and displacement field of the surrounding rock using the backfilling method show an asymmetrical distribution, the movement, deformation, and failure increase slowly, and the increase of the strain is relatively stable. Compared with the caving method, the range and degree of the surrounding rock disturbed by the mining stress are lower. The results of numerical simulation and physical similarity simulation experiment are generally consistent with the theoretically derived results. Overall, this study can provide theoretical basis for the safe and efficient production of steeply dipping coal seams.

GIS Based Coal Seam Floor DEM Construction According to Floor Contours and Considering Faults Distribution

2014 ◽  
Vol 1046 ◽  
pp. 516-520
Author(s):  
He Yu Zhang ◽  
Fan Lei ◽  
Fei Huang
Keyword(s):  
Spatial Distribution ◽  
Coal Seam ◽  
Three Dimensional ◽  
Coal Production ◽  
Mine Design ◽  
Coal Seams ◽  
Inverse Distance Weighted ◽  
Coal Deposits ◽  
Distance Weighted ◽  
Inverse Distance

Coal seam floor contours are one of the most important 8 mine maps, and was usually used for coal mine decision-making. However, the graph, which was expressed as lines, has many disadvantages, including inadequate intuitive, poor visibility, and weak in expression of three-dimensional morphology formation. Thus, the readers have to spend more time to reveal the spatial distribution of coal deposits. According to the coal seam floors contours, and considering the constraints of faults in coal seams, the following steps were implemented to acquire coal seam floor DEM, which are: 1) contours discrete; and 2) interpolation using Inverse Distance Weighted method (IDW). The process was easy-manipulated, and the results could reflect the spatial distribution of coal seams in an objective, intuitively, and strong visibility manner. The method could facilitate and guide the analysis of mine design and coal production.

scholarly journals Failure Mechanism and Control Technology of Thick and Soft Coal Fully Mechanized Caving Roadway under Double Gobs in Close Coal Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Shengrong Xie ◽  
Xiaoyu Wu ◽  
Dongdong Chen ◽  
Yaohui Sun ◽  
En Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Field Distribution ◽  
Control Technology ◽  
Coal Seams ◽  
Anchor Bolt ◽  
Anchor Cable ◽  
Coal Pillars ◽  
Seam Mining ◽  
And Control

The surrounding rock of the roadway under double gobs in the lower coal seams is partially damaged by the mining of the upper coal seam and the stress superimposition of the stepped coal pillars. What is worse, the upper layer of the roof is collapse gangue in double gobs, which makes the anchor cable unable to anchor the reliable bearing layer, so the anchoring performance is weakened. The actual drawing forces of the anchor bolt and anchor cable are only approximately 50 kN and 80 kN, respectively. The roadway develops cracks and large deformations with increasing difficulty in achieving safe ventilation. In view of the above problems, taking the close coal seam mining in the Zhengwen Coal Mine as the engineering background, a theoretical calculation is used to obtain the loading of the step coal pillars and the slip line field distribution of the floor depth. The numerical simulation monitors the stress superimposition of stepped coal pillars and the distribution of elastoplastic areas to effectively evaluate the layout of mining roadways. The numerical simulation also analyzes the effective prestress field distribution of the broken roof and grouting roof anchor cable. A laboratory test was used to monitor the strength of the grouting test block of the broken coal body. Then, we proposed that grouting anchor cable be used to strengthen the weak surface of the roof and block the roof cracks. From on-site measurement, the roadway was seen to be arranged in the lateral stress stabilization area of the stepped coal pillars, the combined support technology of the grouting anchor cable (bolt) + U type steel + a single prop was adopted, the roadway deformation was small, the gas influx was reduced, and the drawing force of the anchor bolt and the anchor cable was increased to approximately 160 kN and 350 kN, respectively. The overall design and control technology of the roadway can meet the site safety and efficient production requirements.

Numerical Simulation of Seepage Field in Aquifer under the Coal Seam

2014 ◽  
Vol 955-959 ◽  
pp. 3120-3124
Author(s):  
Kai Bian ◽  
Shi Lei Chen ◽  
Xue Yuan Li ◽  
Ying Wang Zhao
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Coal Seam ◽  
Three Dimensional ◽  
Seepage Field ◽  
Limestone Aquifer ◽  
Flow Models ◽  
Hydrogeological Parameters ◽  
Simulation Results ◽  
Technical Basis

In order to figure out seepage field in aquifer under the coal seam, the geology and hydrogeology conditions systematically of study area were analyzed, hydrogeological conceptual model was generalized, mathematical model was built, seepage field of the Taiyuan limestone aquifer was simulated with software Feflow. Simulation results show that hydrogeological parameters of Taiyuan limestone aquifer change greatly in different partitions. The model also indicates the heterogeneity of karst fissure of Taiyuan limestone aquifer. The drainage quantity is from the Ordovician limestone aquifer besides supplying from runoff of upstream and capture excretion of downstream. The research is an attempt to simulate the seepage field in aquifer under coal seam, to some extent, it also provides a technical basis for safe coal mining and as a reference for simulation constructions of three-dimensional groundwater flow models in similar coal mines.

The Study on Roadway Layout in Coordination of Mining Coal Seams Base on Failure of Floor Strata

2014 ◽  
Vol 889-890 ◽  
pp. 1362-1374 ◽  
Author(s):  
Yong Zhang ◽  
Chun Lei Zhang ◽  
Chun Chen Wei ◽  
Ya Dong Liu ◽  
Shi Qing Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Simulation Software ◽  
Coal Seams ◽  
Group Coordination ◽  
Mining Coal ◽  
Two Sides

In order to make sure the reasonable roadway layout in lower seam of close coal mining group coordination in Lijiahao coal mine, firstly, applying the theoretical analysis and geological radar detection to get the influence depth of mining from the up coal seam 2-2 to the floor is about 20m, the results show that the thickness of complete strata is about 15m, then determining to use the outward alternate entries in lower seam roadway by using theoretical analysis. At last, determining the distance of outward alternate entries is 12-14m by using FLAC3D numerical simulation software to simulate the change of stress and displacement in roof floor and two sides of roadway.

Three-Dimensional Numerical Simulation of the Mass Exchange Between Longwall Headings and Goafs, in the Presence of Methane Drainage in A U-Type Ventilated Longwall / Symulacja Numeryczna 3D Procesów Wymiany Masy W Układzie Wyrobiska Ścianowe Zroby, W Aspekcie Prowadzenia Odmetanowania Ściany Przewietrzanej Systemem Na „U”

2013 ◽  
Vol 58 (3) ◽  
pp. 705-718
Author(s):  
Przemysław Skotniczny
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Coal Seam ◽  
Mass Exchange ◽  
Experimental Analysis ◽  
Three Dimensional ◽  
Underground Mines ◽  
Test Cases ◽  
Methane Drainage ◽  
Invaluable Tool

Abstract The phenomena related to the occurrence of methane in underground mines pose a considerable danger in the process of coal seam exploitation. Quite often, experimental analysis falls short of investigating their areas of origin (goafs area, affected rock mass, the tail gate area with abandoned excavation). Therefore, an invaluable tool for evaluating the risk involved in the exploitation process might be the numerical simulation of the phenomenon in question, carried out with the use of the latest CFD methods. Due to its application, we are able to recreate and predict the mechanism of the studied phenomenon, with certain assumptions and simplifications made. The present paper discusses the results of the numerical simulation of the process of mass exchange occurring between affected rock mass and longwall headings. The calculations were performed for two test cases - 100 meter long walls.

Research on Verification Method of OpenGL Simulated Image Based on Camera Calibration

2014 ◽  
Vol 602-605 ◽  
pp. 3859-3862 ◽  
Author(s):  
Teng Fei Gao ◽  
Zhao Yang Zeng
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Validity And Reliability ◽  
Simulated Image ◽  
Charge Coupled Device ◽  
Verification Method ◽  
Point Pair ◽  
Dimensional Object ◽  
Simulated Images

OpenGL can correctly simulate real photogrammetric imaging by setting reasonable parameters. It’s an important tool to achieve the simulation of real three-dimensional object or scene imaging to two-dimensional CCD (Charge-coupled Device) plane. However, the images are lack of reliability verify. To solve this problem, we propose a method that can verify OpenGL simulated images on the basis of analyzing OpenGL image-forming principle. Firstly, the checkerboard images of different positions are taken by real camera and intrinsic and external parameters are calibrated. Subsequently, we use OpenGL to produce the same intrinsic and external parameters of checkerboard image by setting correct parameters. Finally, the simulated and real images’ matching point pair RMSE value is calculated based on Harris operator. By comparison, the validity and reliability of OpenGL simulated images are verified by some numerical simulation.

scholarly journals Radio-Wave Tomography of Inhomogeneities in Biological Media with Multi-Frequency Sounding in the Range 2-8 GHZ

2018 ◽  
Vol 155 ◽  
pp. 01025 ◽  
Author(s):  
Sergey Shipilov ◽  
Aleksandr Eremeev ◽  
Evgeny Balzovsky ◽  
Elena Yurchenko
Keyword(s):  
Radio Wave ◽  
Three Dimensional ◽  
Biological Tissues ◽  
Biological Media ◽  
X Ray ◽  
Non Invasive ◽  
Dynamic Observation ◽  
Dimensional Distribution ◽  
Wave Tomography ◽  
Ray Methods

In this paper, a method for detecting and mapping inhomogeneities in biological tissues using the radio-wave tomosynthesis method is presented. The proposed method of radio-wave tomosynthesis allows us to calculate the three-dimensional distribution of the permittivity of the space under study and, thereby, to detect tissue inhomogeneities and to determine their location and size. Due to their harmlessness for humans, these methods are suitable for dynamic observation of changes in the size of formation, in contrast to x-ray methods, for which regular doses of ionizing radiation are contraindicated. Therefore, the development of non-invasive methods for the search for inhomogeneities in biological media based on radio-wave sounding, which makes it possible to identify pathological formations, is now very relevant.

Safety Analysis of Tunnel in Gob of High Steep Thick Coal Seam (II) - 3-D Numerical Simulation for Mechanics of Initial and Secondary Support Structure

2011 ◽  
Vol 71-78 ◽  
pp. 1539-1545
Author(s):  
Wen Bin Lu ◽  
Yi Min Wu ◽  
Jie Chen ◽  
He Lin Fu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Treatment Plan ◽  
Three Dimensional ◽  
Axial Direction ◽  
Tunnel Structure ◽  
Support Structure ◽  
Thick Coal Seam ◽  
Highway Tunnel ◽  
Secondary Support

Taking Wusongshan Tunnel in Tongling City as an example, three-dimensional numerical simulation of new large span highway tunnel built directly through gob of steep coal seam is carried out to study the response of tunnel structure induced by mining. The results showed that, (1) Though immediately backfilling after extraction can prevent the tunnel structure from impact of mining below the tunnel, it is still necessary to forbid extraction below the tunnel consildering the duration time of the extraciton and backfilling activity. (2) Considering the long-term settlement of gob of steep coal seam, net height of the tunnel should be enlarged 50cm to ensure enough space for operation. (3) The tensile and pressive stress of the support structure in the bottom and roof section of the gob are obviously high than other, so comperihencive measures should be taken to reinforce the structure, especially to increase the tensile strength in axial direction. (4) Fortification intensity can be reduced but the fortification should be enlarged if the continuous reinforcement by steel bar is used at the radial construction joints. Based on these results, treatment plan were developed for Wusongshan Tunnel, which can also be refered for other similar projects.

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.

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