scholarly journals A Mechanical Analysis of Support Instability Risk along the Strike of Coalface in Thick Coal Seam with Large Dip Angle: A Case Study

2021 ◽  
Vol 25 (1) ◽  
pp. 101-108
Author(s):  
Wei Zhang ◽  
Weisheng Zhang ◽  
Dongsheng Zhang ◽  
Dahong Qi ◽  
Ziming He
Keyword(s):  
High Efficiency ◽  
Mining Area ◽  
Mechanical Analysis ◽  
Thick Coal Seam ◽  
Technical Parameters ◽  
Geological Conditions ◽  
Mechanical Models ◽  
Large Mining Height ◽  
Dip Angle ◽  
Working Resistance

To ensure safe and high-efficiency mining in the coalface with large dip angle (LDA) and large mining height (LMH), it is important to study the support stability of the coalface under the corresponding conditions. This study is based on the #3up509 coalface of the Gaozhuang Coal Mine (GCM) affiliated with the Zaozhuang Mining Area (ZMA), for which the mechanical characteristics of support in the coalface with LDA and LMH are analyzed. On this basis, the mechanical models for support tilting and sliding in the coalface are developed. Then support stability along the strike of the coalface during the normal mining period (NMP) and special mining period (SMP) is analyzed. The results show that the critical support tilting resistance during the NMP is 52.2 kN, and the critical support sliding resistance is 183.75 kN, and for the SMP, the values are 2679 kN and 4425 kN, respectively. The use of a two-leg shield support, known as ZY6600-25.5/55 (its rated working resistance is 6600 kN), is investigated, which is proved reasonable for the coalface. The influencing factors of support stability along the strike include technical parameters of the support, mining geological conditions of the coalface and specific conditions during mining. Technical measures, such as installing interlock set to fasten support and adjustable lifting jack, increasing the setting load of the support, and optimizing the support displacement method, are taken to increase the overall support stability in the coalface. The initial aim for a safe and high-efficiency mining at the #3up509 coalface has been achieved through the aforementioned measures.

scholarly journals Research on the Influence of the Key Stratum Position on the Support Working Resistance during Large Mining Height Top-Coal Caving Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Baisheng Zhang ◽  
Zhiping Yang ◽  
Chunxu Ji ◽  
Zefeng Guo ◽  
Haoyang Li
Keyword(s):  
Mining Method ◽  
Thick Coal Seam ◽  
Key Stratum ◽  
Movement Characteristics ◽  
Geological Conditions ◽  
Large Mining Height ◽  
Working Resistance ◽  
Mining Height ◽  
Overlying Strata ◽  
Layer Position

In recent years, in order to increase the coal recovery rate, the large mining height fully mechanized top-coal caving mining has been widely used because it has the advantages of both fully mechanized mining method and large mining height mining method. When this mining technology is used to exploit thick coal seam under upper goaf, the movement characteristics of the overlying strata and the bearing structure formed by the broken rock are complicated, which results in the abnormal pressure during mining, such as severe coal slabs and hydraulic supports being crushed. The key to solve these problems is to study the movement law and the structural evolution characteristics of the overlying strata during large mining height fully mechanized top-coal caving mining, and the movement characteristics of the overlying strata are all determined by the layer-position of the key stratum. UDEC models with different layer-position of the key stratum are established to investigate the influence of the key stratum position on the support working resistance during large mining height top-coal caving mining. Through comprehensive research, the source of support resistance comes from under different geological conditions was analyzed, and the formula for estimating the maximum support working resistance was deduced. In addition, in order to release the severe pressure during large mining height fully mechanized top-coal caving mining, it is recommended to use hydraulic fracturing method to weaken the key stratum in situ.

scholarly journals Pressure-Arching Characteristics in Roof Blocks during Shallow Coal Mining

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yanhai Zhao ◽  
Shuren Wang ◽  
Paul Hagan ◽  
Lianwei Ren ◽  
Zhengsheng Zou
Keyword(s):  
Coal Mining ◽  
Mining Area ◽  
Horizontal Stress ◽  
Linear Distribution ◽  
Arch Models ◽  
Thick Coal Seam ◽  
Roof Structure ◽  
Large Mining Height ◽  
Mining Face ◽  
Nonlinear Distribution

To reveal the performance of the stepped subsidence and the strong roof weighting during shallow coal mining, taking the fully mechanized mining face with large mining height in the Shendong mining area in China as the engineering background, theoretical analysis and numerical simulation were used to analyze the pressure-arching effect of the hanging roof blocks. Three typical pressure-arch models of the roof structure were proposed, such as the symmetrical pressure-arch of two key blocks, the step pressure-arch of multiple key blocks, and the rotative pressure-arch of multiple key blocks. Results indicate that the horizontal stress displays a nonlinear distribution at the abutments of the symmetrical pressure-arch, and there is a linear distribution of horizontal stress with a higher peak value at the midspan of the pressure-arch. The high horizontal stress at the arch abutment is necessary to form the rotative pressure-arch of multiple key blocks. The horizontal stress is relatively less at the arch abutment of the step pressure-arch structure. The main key block is easier to slide in this structure as the boundary horizontal stresses display the nonlinear distribution. The results are of instructive significance for roof weighting forecast and strata control during shallow horizontal mining for a thick coal seam.

The Numerical Simulation of Overburden Strata Failure Law by Full-Mechanized Caving Mining in Extra Thick Coal Seams

2014 ◽  
Vol 962-965 ◽  
pp. 1179-1182 ◽  
Author(s):  
Shao Jie Feng ◽  
Xue Fang Zhao ◽  
Shi Guo Sun
Keyword(s):  
Numerical Simulation ◽  
Mining Area ◽  
Fracture Zones ◽  
Thick Coal Seam ◽  
Thick Seam ◽  
Fractured Zone ◽  
Working Face ◽  
Geological Conditions ◽  
Close Proximity ◽  
Superposition Effect

Given the irrationality and limitations in thick coal seam of the empirical formula of height of water flowing fractured zone , this article reveals the special thick seam fully mechanized mining damaging rules of overlying rock and determines the height of water flowing fractured zone with 3D finite element numerical simulation,according to the complex geological conditions and the special thick seam fully mechanized mining methods of Laohutai ore mining working face E5400 as an example. Results show that the destruction of repeated mining area of the overlying rock will have superposition effect and the superposition effect will increase with the development of mining; the fracture sharp of water fracture zones is in close proximity to the "arch". Simulation results and the actual detection height fitting is better, so it assesses the range of overburden water flowing fracture zones and rationality of the height.

Roadway Supporting Technology in Fully Mechanized Workface with Large Mining Height of Specially Thick Coal Seam in Datong Mining Area

2012 ◽  
Vol 204-208 ◽  
pp. 1611-1616 ◽  
Author(s):  
Guo Liang Lu ◽  
Chen Wang ◽  
Yao Dong Jiang ◽  
Hong Wei Wang
Keyword(s):  
Coal Seam ◽  
High Reliability ◽  
Soft Rock ◽  
High Strength ◽  
Mining Area ◽  
Thick Coal Seam ◽  
Roadway Safety ◽  
Large Mining Height ◽  
Soft Rock Roadway ◽  
Mining Height

Aimed at the supporting problems in the fully mechanized roadway with large mining height of the specially thick coal seam in workface 8105 in Tashan coal mine, the “three highs with one low” supporting technology of high strength, high stiffness, high reliability and low support density was adopted to solve the roadway supporting problems of specially high coal side and specially large section and effectively control the surrounding rock deformation and ensure the roadway safety. It also increased the roadway excavation speed which made good conditions for fast advance of the fully mechanized workface, and it made the soft-rock roadway supporting technology in Datong mine area develop into a new level.

scholarly journals Disastrous Mechanism of Water Discharge in Abandoned Gob above the Stope in Mining Extra-Thick Coal Seam

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Haixiao Lin ◽  
Feng Yang ◽  
Zhengzheng Cao ◽  
Yue Wang ◽  
Xiaojian Jiao
Keyword(s):  
Coal Seam ◽  
Water Discharge ◽  
Mining Area ◽  
Thick Coal Seam ◽  
Research Results ◽  
Key Stratum ◽  
Working Face ◽  
Geological Conditions ◽  
Induced Fractures ◽  
Seam Mining

The Datong mining area is a typical double system coal seam mining area in China, where the Jurassic and Carboniferous coal seams are mined simultaneously. The upper Jurassic coal seam has been largely mined, leaving a large amount of gob area. Besides, a large amount of harmful water is accumulated. With the exploitation of the 3-5# extra-thick coal seam in the Carboniferous system, the scope of overburden damage is greatly increasing, and the mining fracture field is further developed. Once the mining-induced fractures connect with the overlying gob, it is easy to induce the water discharge disaster. With the mining geological conditions of the 8202 working face in the Tongxin coal mine as references, the disastrous mechanism of water discharge in the abandoned gob above the stope in the mining extra-thick coal seam is researched by numerical simulation with the UDEC numerical software, and the research results are obtained. The water in the overlying gob percolates through the mining-induced fractures in the higher key layer forming a “shower” seepage pattern. The water in the above gob converges in the key fracture channel, flowing into the working face. The seepage in the fractures in the high key stratum experiences the process of increase, decrease, and stabilization, related with the stretching and extrusion deformation between the high key stratum blocks. Compared with other fractures, the flow rates in the No.2 and No.4 fractures in the far field key lay are larger, because the fractures are in the tension state, forming the “saddle-shaped” flow pattern. The influencing distance of mining-induced seepage is about 80 m in front of the working face. The research results provide a guided reference for the prediction and prevention of water discharge disaster in an abandoned gob above the stope in a mining extra-thick coal seam.

Design of Space Sliding Rails and Mechanical Analysis

2014 ◽  
Vol 624 ◽  
pp. 207-212
Author(s):  
Fu Pei Liu ◽  
Jian Zhong Shang ◽  
Zi Rong Luo ◽  
Tao Zhang ◽  
Nai Hui Yu
Keyword(s):  
Carrying Capacity ◽  
Simulation Analysis ◽  
Mechanical Analysis ◽  
The State ◽  
Mechanical Models ◽  
Design Requirements

Unlike commercial sliding rails, space sliding rails need to meet complex mechanical requirements in the state of ground tooling, launch and on-orbit. The former could slide smoothly while their carrying capacity is low. As a result, they cannot be applied directly to the space stations, manned spacecrafts and other space probes. Hence, it is necessary to design a kind of full-pulling sliding rails which can be suitable for three completely different mechanical conditions. In this paper, we firstly built the mechanical models of the ground tooling, launch and on-orbit state, then a kind of sliding rails is designed according to the mechanical models, finally, a simulation analysis was carried out on the designed sliding rail. The result shows that this kind of sliding rails meets all the design requirements, which verifies the validity of the models.

Equilibrium Temperature Calculation of the Sulfur Isotope in Dongzhongla Pb-Zn Deposit in Tibet

2015 ◽  
Vol 1092-1093 ◽  
pp. 1394-1397
Author(s):  
Guang Chun Fei ◽  
Yi Fan Yu ◽  
Ke Qiang Hua
Keyword(s):  
Sulfur Isotope ◽  
Equilibrium Temperature ◽  
Mining Area ◽  
Isotopic Equilibrium ◽  
The North ◽  
Geological Conditions ◽  
Typical Type ◽  
Lead Zinc ◽  
Block Based ◽  
Exploration Area

The Dongzhongla Pb-Zn deposit, a newly-discovered medium-sized deposit, is located in the north margin of the eastern Gangdese, central Lhasa block. Based on the analysis of the ore-forming geological conditions in this deposit, sulfur isotope of this deposit were analyzed, and S isotopic equilibrium temperature of mineral pairs (sphalerite and galena) were calculated. This study has shown that the sulfur isotopic equilibrium temperature of sphalerite and galena in Dongzhongla Pb-Zn deposit ranged from 185℃ to 296℃. It indicated that the equilibrium temperature decreased gradually from the skarn stage to sulfide stage. The equilibrium temperature can be used as the reference of metallogenic temperature for Dongzhongla Pb-Zn deposit. DongzhongLa deposit is the typical type of skarn Lead-zinc deposit. East of the Dongzhongla mining area is the priority exploration area.

scholarly journals Mechanism of Secondary Breakage in the Overlying Strata during Repetitious Mining of an Ultrathick Coal Seam in Design Stage

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Hui Li ◽  
Dongsheng Zhang ◽  
Shuyin Jiang ◽  
Gangwei Fan ◽  
Mengtang Xu
Keyword(s):  
Coal Seam ◽  
Mining Area ◽  
Design Stage ◽  
Mining Method ◽  
Joint Stability ◽  
Mechanical Models ◽  
Physical Simulations ◽  
Research Findings ◽  
New Feature ◽  
Overlying Strata

When designing the mining of an ultrathick coal seam, the laws governing movement in the overlying strata during mining are a fundamental issue based on which several problems are addressed, including determining the mining method and the roadway arrangement, controlling the surrounding strata, and selecting the devices. The present paper considers possible problems related to strata overlying a large mining space subjected to repeated disturbances during the mining of an ultrathick coal seam, including repeatedly broken strata and the existence or inexistence of the structure. The BM coal seam in the No. 2 coal mine of the Dajing mining area in the East Junggar coalfield is studied. Physical simulations are performed on the movements of the overlying strata during slicing mining of the ultrathick coal seam, revealing the new feature of “break-joint stability-instability-secondary breakage” in the overlying strata. Mechanical models are constructed of the secondary breakage of the overlying strata blocks under both static and impact loading, and mechanical criteria are proposed for such breakage. Based on the research findings, methods for controlling the surrounding strata during slicing mining of an ultrathick coal seam are proposed, including increasing the mining rate and designing reasonable heights for the slicing mining.

Modeling and Mechanical Analysis of Snake Robots on Cylinders

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Chaoquan Tang ◽  
Peng Li ◽  
Gongbo Zhou ◽  
Deyuan Meng ◽  
Xin Shu ◽  
...  
Keyword(s):  
Mechanical Analysis ◽  
Point Of View ◽  
The Body ◽  
Optimal Method ◽  
Tree Structures ◽  
Snake Robot ◽  
Mechanical Models ◽  
And Performance ◽  
The Relationship ◽  
Snake Robots

The narrow and redundant body of the snake robot makes it suitable for the inspection of complex bar structures, such as truss or tree structures. One of the key issues affecting the efficient motion of snake robots in complex bar structures is the development of mechanical models of snake robots on cylinders. In other words, the relationship between the payload and structural and performance parameters of the snake robot is still difficult to clarify. In this paper, the problem is approached with the Newton–Euler equations and the convex optimal method. Firstly, from the kinematic point of view, the optimal attitude of the snake robot wrapped around the cylinder is found. Next, the snake robot is modeled on the cylinder and transformed into a convex optimization problem. Then, the relationship between the payload of the snake robot on the cylinder and the geometric and attitude parameters of the body of snake robots is analyzed. Finally, the discussion for the optimal winding attitude and some advices for the design of the snake robot are proposed. This study is helpful toward the optimal design of snake robots, including geometry parameters and motor determination.

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