scholarly journals Investigation of the Optimization of Unloading Mining Scheme in Large Deep Deposit Based on Vague Set Theory and Its Application

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jia Sheng ◽  
Wen Wan ◽  
Dongrui Liu ◽  
Feifei Jiang ◽  
Xiangdong Li ◽  
...  
Keyword(s):  
Set Theory ◽  
Large Scale ◽  
High Stress ◽  
Mining Area ◽  
Technical Problems ◽  
Deep Mining ◽  
Vague Set ◽  
Mining Depth ◽  
Metal Mines ◽  
Selection Of

With the development of shallow surface mineral resources in metal mines, it is gradually turning to the stage of deep mining. According to the current mining depth and the average annual depth, during the period of “14th Five-Year Plan,” one-third of the underground metal mines will reach or exceed the mining depth of 1,000 m, with the deepest being 2,000 m. In the stage of deep mining, mines will face the conditions of high stress, high temperature, high well depth, and strong mining disturbance, which will greatly increase the difficulty of large-scale deep mining. Among them, the high ground stress environment is the principal problem of many technical problems in deep mining. The selection of mining method has become a prerequisite for solving the problem of efficient and safe mining of deep deposits. In this paper, the vague set theory was introduced into the selection of mining methods and a vague set model for deep unloading mining schemes was established. Taking the Jinchuan No. 2 mining area as the engineering background, four unloading schemes for deep mining were proposed, and the Vague set model was used for optimization. It is concluded that the mining approach with large-section unloading is the optimal unloading mining plan. The application shows that it has the advantages of high unloading efficiency, large production capacity, and low loss index. It has been fully promoted in the deep mining of the mining area. It is feasible and effective to use the vague set theory in the selection of deep unloading mining schemes, which provides a proper approach in the selection of deep unloading mining schemes.

scholarly journals Case Study of the Characteristics and Mechanism of Rock Burst near Fault in Yima Coalfield, China

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhenhua Jiao ◽  
Qiupeng Yuan ◽  
Peng Zou ◽  
Benjun Shi
Keyword(s):  
Rock Burst ◽  
Impact Damage ◽  
High Stress ◽  
Mining Area ◽  
Deep Mining ◽  
High Stress Concentration ◽  
Near Fault ◽  
Mining Depth ◽  
Time Space ◽  
Deep Rock

Deep mining near faults may easily cause rock bursts, which seriously threaten mining safety. Based on the engineering background of deep mining near fault in Yima coalfield, by collecting the rock burst events that happened near fault during deep mining, the correlation between fault structure and time-space features of rock burst was analyzed. The results show that the deep rock burst accounts for 84% in Yima coalfield at 600 m and 93% in the mining area within 1000 m from F16 fault. The risk of rock burst is positively correlated with mining depth and negatively correlated with the distance between mining area and F16 fault, and the frequency and intensity of rock burst near F16 fault increase significantly. Rock burst occurs in high stress concentration area, mainly in roadway, releasing energy level of 1.1 × 104 J–3.5 × 108 J, with impact damage range of 60–500 m. The mechanism of rock burst was explained from the view of the distribution of mining stress in surrounding rock. The stress of coal seam in deep mining near fault increases, and the disturbance effect of fault is obvious. Rock burst is easy to be induced under static and dynamic loads. The occurrence and mechanical characteristics of fault have different effects on rock burst and should be considered when evaluating the risk of rock burst.

Matching area selection of an underwater terrain navigation database with fuzzy multi-attribute decision making method

2018 ◽  
Vol 233 (4) ◽  
pp. 1133-1140 ◽  
Author(s):  
Lihui Wang ◽  
Desheng Sun ◽  
Qingya Liu ◽  
Le Yu
Keyword(s):  
Set Theory ◽  
Membership Functions ◽  
Vague Set ◽  
Topographic Factor ◽  
Vague Sets ◽  
Multi Attribute Decision Making ◽  
Matching Performance ◽  
Simulation Results ◽  
Terrain Matching ◽  
Selection Of

Selecting suitable underwater terrain navigation matching areas is a prerequisite for building an underwater terrain navigation database, which is important for vehicles operating underwater. By using information features to evaluate underwater terrain matching areas, vague sets are proposed to evaluate matching performance. Mathematical models of matching area features are built and topographic factor eigenvalues are obtained. With the topographic factor eigenvalues, fuzzy relationships between factor sets and judge sets are calculated. Vague set uses membership functions and non-membership functions to define the influence of topographic factor eigenvalues on matching suitability. Simulation results demonstrate that vague set theory can overcome the deficiency of single value in fuzzy sets and define the effect of geographic characteristics for matching performance. Based on vague set method, selection rules for terrain navigation matching areas in underwater terrain database are put forward.

scholarly journals Rational size and stability analysis of horizontal isolated pillars in deep mining from caving to filling method

2021 ◽  
Vol 303 ◽  
pp. 01040
Author(s):  
Fan Feng ◽  
Xibing Li ◽  
Shaojie Chen ◽  
Dingxiao Peng ◽  
Zhuang Bian
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Mining Area ◽  
Middle Section ◽  
Deep Mining ◽  
Metal Mines ◽  
Lead Zinc ◽  
Filling Method ◽  
Zinc Mine ◽  
Cut And Fill

For mining using the caving and filling methods in metal mines, determining a suitable size for the isolated pillars—the connecting part of the extension from shallow to deep—is crucial for ensuring safety and efficiency. Considering actual cases involving deep caving and cut-and-fill mining in the Chifeng Hongling lead-zinc mine in Inner Mongolia, China, the reserved thickness range of the horizontal isolation layer is obtained via theoretical analysis. On this basis, the pre-processing software HyperMesh is used to build a high-precision hexahedral grid model of the mining area, and the three-dimensional geological model of the mining area is imported into the finite-difference software FLAC3D. The stress field, displacement field, and plastic area evolution law of pillars (horizontally isolated pillars and adjacent rib pillars) in the stope of the ninth middle section after excavation are analyzed via numerical simulation inversion of the selected scheme of horizontal isolated pillars. The numerical simulation results show that the scheme employed to retain the upper horizontal isolated pillars in the ninth middle section involves reserving thicknesses of 8 m and 32 m at average ore body thicknesses of 15 m and 35 m, respectively. These results can provide theoretical guidance and a basis for safe and efficient mining of deep metal mines.

scholarly journals Properties and Application of Backfill Materials in Coal Mines in China

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Jixiong Zhang ◽  
Meng Li ◽  
Abbas Taheri ◽  
Weiqing Zhang ◽  
Zhongya Wu ◽  
...  
Keyword(s):  
Large Scale ◽  
Coal Mines ◽  
High Stress ◽  
High Water ◽  
High Water Content ◽  
Environmental Aspects ◽  
Coal Resources ◽  
Mining Areas ◽  
Mining Depth ◽  
Backfill Materials

Coal is the basic resource underpinning energy generation in China, however, constant, large-scale mining of coal results in many problems such as ecological destruction of mining areas. As a result, backfilling of solid waste underground is proposed to control strata and surface subsidence and to protect the environment. At present, these materials, such as granular material, cemented material and high-water-content materials are mainly used for backfilling. This study summarised the types of backfill materials that are used in coal mines in China along with the backfilling process. Moreover, distribution and characteristics of mines backfilled with these backfill materials were obtained and analysed. Considering the socio-environmental aspects that affect backfilling, this research proposed a guideline for the selection of backfill materials and then analysed specific engineering cases of three backfill materials. In addition, the future development of backfill materials was discussed. With extensive extraction of shallow coal resources in China and, therefore, rapid depletion of coal resources in eastern regions of China, coal mining depth is increasing significantly. As a result, it is required to investigate new backfill materials suited for the deep high-stress environment.

Research on Surface Deformation with Increasing Mine Depth

2011 ◽  
Vol 243-249 ◽  
pp. 5890-5893
Author(s):  
Gang Chen ◽  
Qiong Wang
Keyword(s):  
Surface Deformation ◽  
Large Range ◽  
Reference Value ◽  
Mining Area ◽  
Deep Mining ◽  
Mining Depth ◽  
Practical Engineering ◽  
Original Rock ◽  
Mine Depth ◽  
The Relationship

After ore mined, the equilibrium state of original rock stress around mining area is damaged, causing surface deforming at large range. With the increasing resource needing and mining intensity, the mines all over the world are gradually in a stage of deep mining, so it is important to study the principle of surface deformation under the condition of deep mining. Finite element method is used to simulate mine process with increasing depth, and the relationship between mining depth and surface deformation is achieved. The result has important reference value to practical engineering.

Impact analysis of pressure-relief blasting on roadway stability in a deep mining area under high stress

2021 ◽  
Vol 110 ◽  
pp. 103781
Author(s):  
Yi Luo ◽  
Kun Xu ◽  
Junhong Huang ◽  
Xinping Li ◽  
Tingting Liu ◽  
...  
Keyword(s):  
Impact Analysis ◽  
High Stress ◽  
Mining Area ◽  
Pressure Relief ◽  
Deep Mining ◽  
Roadway Stability

scholarly journals Ground Subsidence Evolution from 1000 m Deep Mining: A Case Study in Fengfeng Mining Area

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yueguan Yan ◽  
Ming Li ◽  
Jibo Liu ◽  
Weitao Yan ◽  
Jinman Zhang ◽  
...  
Keyword(s):  
Eastern China ◽  
Mining Area ◽  
Ground Subsidence ◽  
Small Displacement ◽  
Deep Mining ◽  
Deep Mine ◽  
Surface Movement ◽  
Mining Depth ◽  
Movement And Deformation ◽  
Influence Radius

The mining of coal resources in eastern China has entered the stage of deep mining, and many mines have reached the depth of 1000 meters. Different from shallow and moderate depth mining, the temporal and spatial evolution regulation of surface movement and deformation under deep mining has its particularity. Combining with the geological and mining conditions of Fengfeng mining area, this paper systematically studies the characteristics of surface movement under the condition of shallow, moderate, and near kilometer mining depth. By means of field measurement, InSAR monitoring, we get the subsidence data under different mining depth and get the relevant subsidence parameters by inversion. Through comparative analysis, the special law of subsidence under the mining depth of 1000 meters is obtained. The results show that under the condition of nearly 1000 meters mining depth, the surface movement and deformation have the characteristics of large displacement angle, small displacement deformation value, and large main influence radius. The regulation of small proportion of active period of maximum subsidence point, gentle shape of surface movement basin, and low mining adequacy are obtained. The research results provide technical references for deep mining under buildings, railways, and water bodies and provide basis and reference for scientific mining and safe recovery of coal pillars in kilometer deep mine.

Numerical Simulation of Factors on Zonal Disintegration in Surrounding Rocks of Deep Roadways

2012 ◽  
Vol 518-523 ◽  
pp. 5935-5938
Author(s):  
Jian Guo Ning ◽  
Xue Sheng Liu ◽  
Hai Tao Li
Keyword(s):  
Numerical Simulation ◽  
Rock Strength ◽  
High Stress ◽  
Mining Area ◽  
Simulation Software ◽  
Zonal Disintegration ◽  
Mining Depth ◽  
Damage Degree ◽  
Mining Conditions ◽  
Weak Structure

At the background of geological and mining conditions of typical roadways in Xinwen mining area, using numerical simulation software FLAC-3D, the effects of mining depth, weak structure and rock strength on the characteristics of zonal disintegration in Deep Roadway was studied. Results show that high stress is the premise to form the phenomenon of zonal disintegration; weak structure in surrounding rocks is the key and surrounding rock strength is the determinants of damage degree and scope of rupture zone in deep surrounding rocks. There are important theoretical and practical significances to explore the formation mechanism of zonal disintegration in surrounding rocks of deep roadways, and to ensure safe mining of deep resources.

Platelet Anti-Aggregating Activity and Tolerance of Clopidogrel in Atherosclerotic Patients

1996 ◽  
Vol 76 (06) ◽  
pp. 0939-0943 ◽  
Author(s):  
B Boneu ◽  
G Destelle ◽  
Keyword(s):  
Platelet Aggregation ◽  
Large Scale ◽  
Bleeding Time ◽  
Antithrombotic Activity ◽  
Ambulatory Patients ◽  
Patients At Risk ◽  
Set Up ◽  
Ischemic Events ◽  
Large Scale Clinical Trial ◽  
Selection Of

SummaryThe anti-aggregating activity of five rising doses of clopidogrel has been compared to that of ticlopidine in atherosclerotic patients. The aim of this study was to determine the dose of clopidogrel which should be tested in a large scale clinical trial of secondary prevention of ischemic events in patients suffering from vascular manifestations of atherosclerosis [CAPRIE (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events) trial]. A multicenter study involving 9 haematological laboratories and 29 clinical centers was set up. One hundred and fifty ambulatory patients were randomized into one of the seven following groups: clopidogrel at doses of 10, 25, 50,75 or 100 mg OD, ticlopidine 250 mg BID or placebo. ADP and collagen-induced platelet aggregation tests were performed before starting treatment and after 7 and 28 days. Bleeding time was performed on days 0 and 28. Patients were seen on days 0, 7 and 28 to check the clinical and biological tolerability of the treatment. Clopidogrel exerted a dose-related inhibition of ADP-induced platelet aggregation and bleeding time prolongation. In the presence of ADP (5 \lM) this inhibition ranged between 29% and 44% in comparison to pretreatment values. The bleeding times were prolonged by 1.5 to 1.7 times. These effects were non significantly different from those produced by ticlopidine. The clinical tolerability was good or fair in 97.5% of the patients. No haematological adverse events were recorded. These results allowed the selection of 75 mg once a day to evaluate and compare the antithrombotic activity of clopidogrel to that of aspirin in the CAPRIE trial.

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