scholarly journals Similar Material Simulation Study on Protection Effect of Steeply Inclined Upper Protective Layer Mining with Varying Interlayer Distances

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Zhigang Yuan ◽  
Yaohua Shao ◽  
Zhuohui Zhu
Keyword(s):  
Mechanical Properties ◽  
Coal Mine ◽  
Protective Layer ◽  
Interlayer Distance ◽  
Engineering Practice ◽  
Similar Material ◽  
Pressure Relief ◽  
Protection Effect ◽  
Swelling Strain ◽  
Similar Material Simulation

Protective layer mining, as a dominating regional prevention measure, is generally adopted to prevent and control gas disasters in highly gassy or outburst mines of China. Interlayer distance is one of the most important factors that influences protection effect. However, how does interlayer distance affect the protection effect of steeply inclined upper protective layer mining is not understood fully. According to the engineering practice in Nantong mining district, a new method for similar material simulation experiment of steeply inclined upper protective layer mining is proposed, in which an orthogonal test of similar materials comprising of sand, cement (containing gypsum and fly ash), and water mixture is conducted to obtain relations between proportioning parameters and mechanical properties using a multiple regression method. And then the method is applied to study the protection effect of steeply inclined upper protective layer mining with varying interlayer distances. The results show the following. (1) The proportioning parameters of similar material have strong linear relations with its mechanical properties, and mechanical behaviors of such similar material denote that it can simulate most coal-rock lithologies in coal mine. (2) Both pressure-relief curves and swelling strain curves for protected layer present convex shapes; protection angles at lower excavation boundary are greater than those of upper excavation boundary; with the increase of interlayer distance, the pressure-relief curve evolves from pattern “∩” to pattern “∧” and corresponding pressure-relief region becomes narrower, the center of pressure-relief region tends to transfer to the corresponding center of upper protective layer excavation region, the stress concentration coefficient decreases, the protection angles change little, and the length of the protection region reduces dramatically. (3) The protection region and protection angle calculated based on swelling strain of 3‰ are less than the empirical values based on the dip angle in Provisions, denoting that the method proposed in this study is safer than that in Provisions. The research results provide a useful guide for layouts of roadway and gas drainage boreholes to prevent gas disaster in Nantong coal mine district.

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

Research on the Height of Water-Flowing Fractured Zone under the Weak Roof Strata and Fully Mechanized Caving Condition

2015 ◽  
Vol 1092-1093 ◽  
pp. 1448-1454
Author(s):  
Yan Zhang
Keyword(s):  
Coal Mine ◽  
Drilling Fluid ◽  
Water Inrush ◽  
Test Results ◽  
Similar Material ◽  
Fractured Zone ◽  
Working Face ◽  
Observation Method ◽  
Roof Strata ◽  
Similar Material Simulation

The first working face production has suspend because of the great roof water inrush in Mindongyi coal mine, which has weak roof strata and mining use the fully mechanized caving method. In order to detect the height of water-flowing fractured zone, loses of drilling fluid observation method has carried on the flied test, the results showed that while the full-mechanized caving mining thickness is 7.7 m, the height of water-flowing fractured zone is 79.78 m, and the ratio of height to thickness is 10.36, meanwhile, the numerical simulation and similar material simulation have proved the test results are correct. The study enriched the domestic research fruits of the height of water flowing fractured zone, and provided technical references for Mindongyi coal mine mining.

scholarly journals Research on Deformation Mechanisms of a High Geostress Soft Rock Roadway and Double-Shell Grouting Technology

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fengnian Wang ◽  
Shizhuang Chen ◽  
Pan Gao ◽  
Zhibiao Guo ◽  
Zhigang Tao
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Large Deformation ◽  
Coal Mine ◽  
Soft Rock ◽  
In Situ Stress ◽  
Deformation Monitoring ◽  
Deformation And Failure ◽  
Working Face ◽  
High Geostress

In this study, the deformation characteristics and mechanical properties of coal and rock mass in the S2N5 working face of the Xiaokang coal mine are analyzed to address the problem of large deformation of soft rocks with high in situ stress surrounding roadways. Through a newly developed grouting pipe, a double-shell grouting technology, consisting of low-pressure grouting and high-pressure split grouting, is proposed for the Xiaokang coal mine. In addition, the effect of grouting is evaluated by borehole peeping and deformation monitoring. The results show that the double-shell grouting technology can effectively improve the overall mechanical properties of the surrounding coal and rock mass, preventing the large deformation and failure of the roadway. This technology can be useful when analyzing and preventing large deformation of soft rock roadways.

Research on Supporting Countermeasure of B103W01 Transport Roadway in Shajihai Coal Mine

2013 ◽  
Vol 401-403 ◽  
pp. 2221-2225
Author(s):  
Shu Jiang Zhao
Keyword(s):  
Coal Mine ◽  
Deformation Mechanism ◽  
Soft Rock ◽  
Single Type ◽  
Engineering Practice ◽  
Deformation And Failure ◽  
Constant Resistance ◽  
Supporting Effect ◽  
Deformation Mechanics ◽  
Coupling Support

For the soft rock roadwaysupporting problems, using the conventional methods cannot effectively controlthe deformation and failure. This paper took B103W01 transport gateway projectin Shajihai coal mine as example and analyzed its deformation failure reasonand deformation mechanism and determined the specific measures of transformingcompound mechanism of deformation mechanics into a single type. In the end, weput forward coupling support technology of constant resistance and largedeformation bolt + hollow grouting anchor + corner grouting steel pipe, whichhad been applied to engineering practice. The monitoring results showed thatthe supporting effect was good. So it can be used for reference for the similarconditions of roadway supporting.

Application of Lodrigues Matrix in Coordinate Transformation of Similar Material Simulation Experiment

2012 ◽  
Vol 455-456 ◽  
pp. 204-210
Author(s):  
Guo Wang ◽  
Xi Min Cui ◽  
De Bao Yuan ◽  
Ya Hui Qiu ◽  
Jin Lin Yang ◽  
...  
Keyword(s):  
Coordinate Transformation ◽  
Simulation Experiment ◽  
Similar Material ◽  
Similar Material Simulation

scholarly journals Evaluation of contact fatigue risk of a carburized gear considering gradients of mechanical properties

Friction ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 1039-1050
Author(s):  
Wei Wang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Jinyuan Tang ◽  
Chenxu Jiang
Keyword(s):  
Mechanical Properties ◽  
Fatigue Failure ◽  
Equivalent Stress ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Engineering Practice ◽  
Case Hardening ◽  
Failure Risk ◽  
Spalling Failure ◽  
Carburized Gear

AbstractCarburized gears are widely used in geared machines such as wind turbines. Contact fatigue problems occur in engineering practice, reducing reliabilities of machines. Contact fatigue failures are related to many factors, such as gradients of mechanical properties of the hardening layer. In this work, an elastic-plastic contact model of a carburized gear is developed based on the finite element method to evaluate contact fatigue failure risk, considering variations in hardness and strength. The Dang Van multiaxial equivalent stress is calculated via Python coding within the Abaqus framework. The gradient of yield strength along the depth from case to core is considered. The concept of local material fatigue failure risk is defined to evaluate the probability of pitting failure. The effects of design factors, such as the case hardening depth (CHD), surface hardness, and contact pressure on fatigue failure risk, are studied. As the CHD increases or the surface hardness decreases, the risk of deep spalling failure reduces. The increase in surface hardness leads to a decreased risk of pitting failure, while the variation in CHD hardly affects the pitting failure risk.

Analyze on the Mechanical Properties of Stitched Composites

2011 ◽  
Vol 217-218 ◽  
pp. 1758-1762
Author(s):  
Tao Chang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Low Cost ◽  
Element Model ◽  
Textile Composites ◽  
External Loading ◽  
Engineering Practice ◽  
Textile Composite ◽  
And Performance ◽  
Potential Member

As the most potential member in the textile composite material, stitched textile composites have already been paid a lot attention. By the simply technology form and relatively low cost, stitched composites had attracted many domestic and foreign researchers, and were gradually used in various engineering practice. This paper using 3D micro-finite element method researches the mechanical behavior and performance of stitched composites, establishing a 3D micro-finite element model for the stitched composites under the improved locking suture way. Through analysis, it shows that each material’s stress distribution characteristics under external loading and finds that the results of this paper’s finite element data results matching well with previous studies’ results, proving the feasibility of this study, so it can be used for forecasting the mechanical properties of a variety of practical stitched composites.

scholarly journals Failure Mechanism of a Coal-Rock Combined Body with Inclinations of Structural Planes and a Calculation Model for Impact Energy

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Yi-Chao Zhao ◽  
Ming-Shi Gao ◽  
Yong-Liang He ◽  
Dong Xu
Keyword(s):  
Mechanical Properties ◽  
Failure Mechanism ◽  
Impact Energy ◽  
Coal Mines ◽  
Calculation Model ◽  
Engineering Practice ◽  
Test Results ◽  
Failure Characteristics ◽  
Coal Rock ◽  
Rock Strata

A coal-rock (CR) combined body can be used to simulate structures of coal and rock strata, and its impact-induced failure characteristic conforms more close to engineering practice. Exploring the mechanical properties and impact energy in a CR combined body contributes to better predictions of rock bursts in coal mines. In the study, the mechanical properties of CR combined bodies with four different inclinations (0°, 15°, 30°, and 45°) of structural planes were measured, and also their failure mechanism was analysed. Based on the theory of particle mechanics, a calculation model for impact energy in a CR combined body with inclinations was established and then verified by using monitored acoustic emission (AE) data. The test results showed that inclination affected mechanical properties and failure characteristics of the CR combined body, i.e., the larger the inclination, the lower the strength and impact energy in the CR combined body and the lower the level of damage. The proposed calculation model for impact energy revealed the mechanical essence of energy accumulation and release of a CR combined body, providing a reference for investigating rock burst in coal mines.

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