scholarly journals A Novel Mining Method for Longwall Panel Face Passing through Parallel Abandoned Roadways

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yang Li ◽  
Yuqi Ren ◽  
Nan Wang ◽  
Junbo Luo ◽  
Na Li ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Main Roof ◽  
Mine Pressure ◽  
Horizontal Distance ◽  
Mining Method ◽  
Long Span ◽  
Longwall Panel ◽  
Coal Wall ◽  
Mining Pressure ◽  
Roof Falling

Mining pressure behavior in the process of longwall panel face passing through the parallel abandoned roadways (PARs) is different from the ordinary longwall panel face. It is easy to induce the accident of roof falling, coal wall spalling, and crush accident of shield. In order to reduce the occurrence of mine pressure accidents and ensure safe mining, a new mining method named “swing-inclined” mining method was proposed and was employed in the E13103 of Cuijiazhai coal mine. Based on the process of the longwall panel face passing through the PARs, a long-span and multisupport mass-structure model of the roof was established. The maximum support capacity of shield was calculated combined with stability relation between “roof-shield-PAR-‘similar pillar (SP)’-coal wall.” It provided the basis for determining the reasonable support capacity of shield. Moreover, the sensitivity analysis of influenced factors to the maximum support capacity of shield was carried out by using Matlab software. The sensitivity analysis results indicated that different factors had a different effect on the support capacity of shield. And, the process of passing through the PARs can be divided into 3 stages, depending on the relation between support capacity of shield and width of SP. In different stages, the change degree of support capacity of shield was different. The support capacity of shield is mainly influenced by the hanging distance of the main roof and the horizontal distance between the support point of the coal wall and the breaking position of the main roof. By on-site measurement, the sensitivity analysis results were verified.

scholarly journals Comparative analysis of the mine pressure at non-pillar longwall mining by roof cutting and traditional longwall mining

2019 ◽  
Vol 16 (2) ◽  
pp. 423-438 ◽  
Author(s):  
Peng Zhou ◽  
Yajun Wang ◽  
Guolong Zhu ◽  
Yubing Gao
Keyword(s):  
Pressure Distribution ◽  
Coal Mining ◽  
Longwall Mining ◽  
Mining Industry ◽  
Mine Pressure ◽  
Mining Method ◽  
Working Face ◽  
Distribution Features ◽  
Mining Pressure ◽  
The Stability

Abstract Non-pillar coal mining has been developed and implemented in the recent decades in China's coal mining industry. The non-pillar longwall mining by roof cutting without pre-excavated entry (N00 mining method) is one of the latest non-pillar mining methods and this method has the advantages of reduced roadway drivage ratio and increased resource recovery ratio. Previous studies show that the mining pressure during the working face advancing is one of the main factors that affect the stability of underground structures and the safety production. However, there is no evaluation or analysis of the mining pressure at the mining face using entry retaining with roof pre-cutting and an absence of pre-excavated tail entry. In this paper, both field monitoring and numerical simulation approaches are employed in the analysis of the mining pressure distribution characteristics within a range of the whole working face during the face advancing. The results are compared with the field data and simulation results from the traditional mining method performed in the same coal mine. Results supported the idea that the N00 mining method can generate a low-stress area for the retained entry. The stability of the working face and retained entry can be well maintained due to the mine pressure optimization. This paper can aid in the understanding of structural mechanic modeling and mine pressure distribution features, structural mechanic analysis and mine pressure distribution features of the N00 mining method.

Effective Filling Rate in Filling Mining’s Influence on Overlying Strata’s Movement

2013 ◽  
Vol 734-737 ◽  
pp. 741-745
Author(s):  
Jian Hao ◽  
Yong Kui Shi ◽  
Min Hua Qi ◽  
Lei Zhang
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Pressure Control ◽  
Mine Pressure ◽  
Pressure Curve ◽  
Filling Rate ◽  
A Value ◽  
Admissible Condition ◽  
Coal Wall ◽  
Supporting Degree

Similarities and differences of overlying strata movement rule and abutment pressure distribution between filling stope and traditional strope was analysied guided by “practical mine pressure control theory ”. The admissible condition of strata’s depending from bending failure to caving was put forward, and caving zone’s height was analysied on the basis of this. Results showed that caving zone’s height and resistant force required by hydraulic pillar would decrease leapingly ,until the lowest strata transfer into the main roof, and when pressure was stable main roof’s maximum subsidence would become smaller. With the increase of the effective filling rate, filling body’s supporting degree to overlying would increase, when the filling rate reaches to a value, Coal wall’s edge would not appear the plastic zone, the abutment pressure curve is monotone decline with the peak near coal wall edge .

scholarly journals The influence of advance speed on overburden movement characteristics in longwall coal mining: insight from theoretical analysis and physical simulation

2021 ◽  
Vol 18 (1) ◽  
pp. 163-176
Author(s):  
Penghua Han ◽  
Cun Zhang ◽  
Zhaopeng Ren ◽  
Xiang He ◽  
Sheng Jia
Keyword(s):  
Physical Simulation ◽  
Impact Load ◽  
Main Roof ◽  
Longwall Face ◽  
Mine Safety ◽  
Efficient Production ◽  
Time Space ◽  
Mining Pressure ◽  
The Impact ◽  
Advance Speed

Abstract The advance speed of a longwall face is an essential factor affecting the mining pressure and overburden movement, and an effective approach for choosing a reasonable advance speed to realise coal mine safety and efficient production is needed. To clarify the influence of advance speed on the overburden movement law of a fully mechanised longwall face, a time-space subsidence model of overburden movement is established by the continuous medium analysis method. The movement law of overburden in terms of the advance speed is obtained, and mining stress characteristics at different advance speeds are reasonably explained. The theoretical results of this model are further verified by a physical simulation experiment. The results support the following conclusions. (i) With increasing advance speed of the longwall face, the first (periodic) rupture interval of the main roof and the key stratum increase, while the subsidence of the roof, the fracture angle and the rotation angle of the roof decrease. (ii) With increasing advance speed, the roof displacement range decreases gradually, and the influence range of the advance speed on the roof subsidence is 75 m behind the longwall face. (iii) An increase in the advance speed of the longwall face from 4.89 to 15.23 m/d (daily advancing of the longwall face) results in a 3.28% increase in the impact load caused by the sliding instability of the fractured rock of the main roof and a 5.79% decrease in the additional load caused by the rotation of the main roof, ultimately resulting in a 9.63% increase in the average dynamic load coefficient of the support. The roof subsidence model based on advance speed is proposed to provide theoretical support for rational mining design and mining-pressure-control early warning for a fully mechanised longwall face.

scholarly journals Research and Application of an Innovative 110 Mining Method in Gob-Side Half Coal Rock Entry Retaining

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Eryu Wang ◽  
Xiangdong Chen ◽  
Xiaojie Yang
Keyword(s):  
Recovery Rate ◽  
Mine Pressure ◽  
Mining Method ◽  
Time Consumption ◽  
Coal Recovery ◽  
Working Face ◽  
Constant Resistance ◽  
Movement Characteristic ◽  
Coal Rock ◽  
Maximum Subsidence

In order to solve the problems of the high cost and time consumption of half coal rock entry driving, low coal recovery rate, and stress concentration on filling support body of retained entry along gob, the innovative 110 mining method based on pressure relief by roof cutting was adopted in 6302 thin coal seam working face of Baoshan Coal Mine. First the technical principle and key technology of this mining method was presented. Then, through theoretical analysis and calculation, engineering experience, and field test, the key parameters such as the length of constant resistance anchor cable, the cutting angle and height of presplitting blasting, the charge structure, and the blocking-gangue support structure were determined and conducted in the retained entry. The broken expanded coefficient varying law of caved gangue with time and space was obtained, which revealed roof movement characteristic. The displacement monitoring curve of the roof and floor indicated that the maximum subsidence of the roof was about 150 mm and the maximum amount of floor heaving was 100 mm, which were quite small. The field monitoring data indicated that the entry retaining effect is good, which indicated that the innovative 110 mining method can be an effective way for reducing the high cost and time consumption of half coal rock entry driving, enhancing the coal recovery rate and preventing the dynamic mine pressure disasters.

scholarly journals Mechanical Model of the Initial Leg Pressure Increment of the Shield and Its Application to Monitor Roof Load in Longwall Panels

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Like Wei
Keyword(s):  
Coal Mine ◽  
Pressure Difference ◽  
Mechanical Model ◽  
Main Roof ◽  
Mine Pressure ◽  
Initial Stage ◽  
Proposed Model ◽  
Pressure Increment ◽  
The Relationship ◽  
Leg Pressure

The shield pressure cannot always be used to represent the upper load of longwall panels, since its value is steady or even decreases by the yielding action. However, the leg pressure increment of the shield (LPIS) at the initial stage is not influenced by yielding and could therefore be an important factor to judge the state of overlying loads. In this study, a mechanical model is established to analyze the relationship between the overlying loads of the main roof and LPIS after cutting. There is a linear positive correlation between leg pressure increment and overlying loads and a second-order relationship between leg pressure increment and length of main roof cantilever in the proposed model. Therefore, it can be used to determine the magnitude of roof weighting strength in different periods as well as the length of the main roof cantilever in a period. Finally, the mine pressure difference between the period of fully mechanized mining and the period of fully mechanized caving mining in the MinDong-1 coal mine serves to verify the rationality of the proposed model.

Cutting Roof Roadway Parameter Optimization Simulation Analysis

2015 ◽  
Vol 741 ◽  
pp. 179-182
Author(s):  
Yan Min Shu ◽  
Yong Li Liu
Keyword(s):  
Shear Stress ◽  
Stress State ◽  
Rock Strength ◽  
Simulation Analysis ◽  
Main Roof ◽  
High Impact ◽  
Mine Pressure ◽  
Working Face ◽  
Optimization Simulation ◽  
Concentration Degree

Contrast simulation analysis under different cutting distance between top lane, cut the top lane area stress state, according to different stress state analysis of the optimal cutting top lane spacing, so as to realize the optimization of cutting top lane setting parameters.Results show that due to the inhomogeneity of rock strength, the main roof breaking are mainly shear stress play a role, as a result, the vertical stress of roof fracture need conditions may be much smaller than mine pressure strength limit.Considering cutting top lane for the larger spacing, cutting the top coal lane area of stress concentration degree is higher, easy to cause impact danger, from this aspect to consider cutting the top lane spacing should be small as far as possible, but the spacing is too small and cut the top lane roadway of quantities will increase, at the same time has the potential to cut two top lane of the superposition of stress, high impact and increase the working face danger.

Parametric Sensitivity Analysis of Long-Span Arch-Truss String Structure

2014 ◽  
Vol 919-921 ◽  
pp. 193-198
Author(s):  
Zheng Xian Bai ◽  
Xi Ming Hou ◽  
Shuai Tian ◽  
Jin Zhi Wu
Keyword(s):  
Sensitivity Analysis ◽  
Natural Frequencies ◽  
Simulation Method ◽  
Effective Area ◽  
Monte Carlo Simulation Method ◽  
Sectional Area ◽  
Static Behavior ◽  
Parametric Sensitivity ◽  
Long Span ◽  
String Structure

Parametric sensitivity to static behavior and dynamic characteristics of Long-span Arch-truss String Structures (ATSS), which is based on statistical distribution of parameter errors including elastic modulus of the material, effective area and pre-stress of cable, and thickness of steel pipe, etc., was studied by Monte Carlo simulation method of ANSYS. The error of sectional area of cable is found to be the most sensitive parameter and the natural frequencies are greatly sensitive to the errors of modulus of members. The results help to determine suitable updating parameters of ATSS, and provide valuable advices to guide the construction control.

scholarly journals The Stability Factors’ Sensitivity Analysis of Key Rock B and Its Engineering Application of Gob-Side Entry Driving in Fully-Mechanized Caving Faces

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hong-Sheng Wang ◽  
Hai-Qing Shuang ◽  
Lei Li ◽  
Shuang-Shuang Xiao
Keyword(s):  
Coal Mine ◽  
Orthogonal Experiment ◽  
Engineering Application ◽  
Main Roof ◽  
Fracture Line ◽  
Rock Block ◽  
Fracture Location ◽  
Mechanics Model ◽  
Geological Conditions ◽  
Coal Wall

To reveal the critical factors of the main roof influencing stability of surrounding rocks of roadways driven along goaf in fully-mechanized top-coal caving faces, this paper builds a structural mechanics model for the surrounding rocks based on geological conditions of the 8105 fully-mechanized caving face of Yanjiahe Coal Mine, and the stress and equilibrium conditions of the key rock block B are analyzed, and focus is on analyzing rules of the key rock block B influencing stability of roadways driven along goaf. Then, the orthogonal experiment and the range method are used to confirm the sensitivity influencing factors in numerical simulation, which are the basic main roof height and the fracture location, the length of the key rock block B, and the main roof hardness in turn. It is revealed that the basic main roof height and its fracture location have a greater influence on stability of god-side entry driving. On the one hand, the coal wall and the roof of roadways driven along goaf are damaged, and the deformation of surrounding rocks of roadways and the vertical stress of narrow coal pillars tend to stabilize along with the increase of the basic main roof height. On the other hand, when the gob-side entry is located below the fracture line of the main roof, the damage caused by gob-side entry is the most serious. Therefore, on-site gob-side entry driving should avoid being below the fracture line of the main roof. At last, industrial tests are successfully conducted in the fully-mechanized top-coal caving faces, 8105 and 8215, of Yanjiahe Coal Mine.

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