scholarly journals Dynamic Evolution Law of Roof Deformation in Continuous Mining and Continuous Backfilling Method

2021 ◽  
Author(s):  
Bin Xu ◽  
Renshu Yang ◽  
Yongliang Li ◽  
Bin Lu
Keyword(s):  
Coal Mine ◽  
Dynamic Change ◽  
Coal Pillar ◽  
Beam Theory ◽  
Dynamic Evolution ◽  
Main Bearing ◽  
Evolution Law ◽  
Continuous Mining ◽  
Bearing Structure ◽  
Roof Deformation

Abstract To investigate the dynamic evolution law of roof deformation in the continuous mining and continuous backfilling (CMCB) method, the alternating bearing characteristics of coal and the backfilling body were obtained through statistical analysis. On the basis of two-step mining and the elastic foundation beam theory, the mechanical model of the entire stage roof deformation was established, and the dynamic change law of roof settlement was obtained. On the basis of the working face of CMCB in Haoyuan Coal Mine, the deformation rule of the two-step mining roof was analyzed. In the first stage of mining, the coal pillar is the main bearing structure, the deformation of the roof is small, and the distribution is wavy. In the second stage, the backfilling body gradually becomes the main bearing structure, and the deformation of the roof significantly increases and exhibits a U-shaped distribution. The results obtained by numerical simulations reveal that four-step mining increases the width of the coal pillars and the roof deformation is effectively controlled during the filling process. After the filling is completed, the roof remains stable under the support of the filling body under different filling modes; therefore, its final settlement remains consistent. Through field measurement, it was found that the CMCB method can effectively control the roof subsidence in Haoyuan Coal Mine.

scholarly journals Study on the Pressure-Bearing Law of Backfilling Material Based on Three-Stage Strip Backfilling Mining

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 211 ◽  
Author(s):  
Xiaoping Shao ◽  
Xin Li ◽  
Long Wang ◽  
Zhiyu Fang ◽  
Bingchao Zhao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Thin Plate ◽  
Coal Mine ◽  
Physical Simulation ◽  
Plate Theory ◽  
Coal Pillar ◽  
Smooth Transition ◽  
Main Bearing ◽  
Working Face ◽  
Rock Load

During strip backfilling mining in coal mines, the backfilling material is the main support structure. Therefore, studying the pressure law of the backfilling material is essential for the safe and efficient mining of coal resources. Based on research into strip backfilling mining at working face number 3216 of the Shanghe Coal Mine, and to smooth transition of overlying strata loads to the backfilling material, this study proposes a three-stage strip backfilling mining method. Based on thin-plate theory, an elastic thin-plate model, a reasonable spacing of strip mining is constructed, and the reasonable mining parameters of “mining 7 m to retain 8 m” at working face number 3216 of the Shanghe Coal Mine are determined. The law of backfilling pressure in three-stage strip backfilling mining is studied through numerical simulation and physical simulation experiments. The results show that field measurement results are basically consistent with the experimental results and numerical simulation results. When three-stage strip backfilling mining is adopted, the stage-one backfilling material is the main bearing body to which the overlying rock load transfers smoothly and gradually, and the structure of the “overburden-coal pillar (or backfilling strip)” in the stope remains stable. In three-stage strip backfilling mining, the overlying rock load is ultimately transferred to the stage-one backfilling material, the stage-two backfilling material is the auxiliary bearing body, and the stage-three backfilling material mainly provides long-term stable lateral support for the stage-one backfilling material.

Similarity simulation study on displacement and stress changes response to coal mining in Longdong coal mine, China

2020 ◽  
pp. qjegh2020-111
Author(s):  
Kai Huang ◽  
Long Xu ◽  
Fusheng Zha ◽  
Zhitang Lu ◽  
Jiwen Wu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Water Inrush ◽  
Coal Pillar ◽  
Working Face ◽  
Field Investigations ◽  
Geological Conditions ◽  
Stress Changes ◽  
Continuous Mining ◽  
The Stability

The complicated geological conditions, including the Fault Sun, in East No. 2 mining sub-area of the Longdong coal mine will influence the stability of strata during mining, leading to serious geological hazards. To circumvent this issue, a similarity simulation experiment was designed and performed in this study, in which the failure characteristics and evolution of displacement and stress within the strata were investigated, and the optimum width of a waterproof coal pillar was determined. The results showed that, as the working face progressed, the coal seam roof gradually deformed, from initial caving of the immediate roof to complete movement and curved subsidence of the entire roof. Significant changes in displacement and stress within the coal seam roof were recorded, and these increased during continuous mining activity. Displacement and stress difference on either side of the fault gradually increased and reached remarkable values with increase in mining distance. On the basis of the experiment results, water inrush is believed to be caused by the interaction between mining and the fault, and, as calculated from parameters collected in field investigations, a waterproof coal pillar of 50 m width should be established to prevent Fault Sun activation, thereby reducing the risk of water inrush from neighbouring aquifers.

Principle of Well-Net Design for Coalbed Methane Exploitation in Coal Mine Area

2014 ◽  
Vol 543-547 ◽  
pp. 3967-3973
Author(s):  
Bao Shan Han
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Design Theory ◽  
Surface Condition ◽  
Coal Pillar ◽  
Negative Influence ◽  
In Situ Stress ◽  
Well Location

There are abundant CBM (Coalbed Methane) in China. These CBM has caused a remarkable problem to the coal-mining in China. In order to improve the structure of Chinese energy and eliminate the risk of coal mine gas, the relevant industries and sections have implemented many explorations in CBM enriched areas. With great achievements, there are many important problems in the actions of CBM exploitation. The disadvantageous interaction of the surface CBM well and the later coal mining has been ignored at all. There are many disadvantages and defects. To solve these problems and eliminate or weaken the disadvantageous, the scientific and reasonable design of surface CBM well location is an important step. With the thinking of surface condition, coal mining plan, the arrangement of coal mine laneway, the direction and scale of the in-situ stress, and thinking more about the negative influence to and of surface CBM well, according to the theories of mining dynamics, mining engineering, mining geomechanics, and the CBM engineering, the design theory of the surface CBM well net can be studied. Finally, the arrangement principle of CBM product well in coal field is presented. The existing or future coal pillar will be a critical location for the surface CBM well location.

scholarly journals Research on Evaluation Index and Application of Rockburst Risk in Deep Strip Mining

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bangyou Jiang ◽  
Hongguang Ji ◽  
Long Fu ◽  
Shitan Gu ◽  
Tong Zou ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Coal Mine ◽  
Coal Pillar ◽  
Width Ratio ◽  
Strip Mining ◽  
Index Method ◽  
Research On Evaluation ◽  
Mechanics Model ◽  
Evolution Characteristics ◽  
Comprehensive Index Method

The practice shows that deep strip mining induces rockburst disaster easily. Accurately evaluating rockburst risk of the strip coal pillar is of great significance for ensuring the safety of deep strip mining. In this paper, the catastrophe mechanics model was used to analyze the abrupt instability condition of strip coal pillar. And the three indicators that are the medium stiffness ratio (k) of the elastic and plastic zone in the coal pillar, the plastic zone width ratio (aY), and the elastic deformation index (Uq) of core zone were put forward with considering the geometry size of coal pillar. Based on the 3202 panel of Gucheng Coal Mine, the evolution characteristics of rockburst risk of coal pillar under different mining widths and coal pillar widths were studied by numerical simulation. The evaluation result shows that the strip coal pillar of the 3202 panel is in danger of strong rockburst, which is more in line with the actual situation than the results of the traditional rockburst tendency identification test and comprehensive index method. These three indicators can be regarded as important indicators to evaluate the rockburst risk in the strip mining engineering field. Based on that, the design principle of strip mining in Gucheng Coal Mine was put forward, which is considered an important reference for similar cases.

scholarly journals Deflection Mechanism and Safety Analysis of Coal Mine Shaft in Deep Soil Strata

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jihuan Han ◽  
Jiuqun Zou ◽  
Chenchen Hu ◽  
Weihao Yang
Keyword(s):  
Coal Mine ◽  
Rational Design ◽  
Coal Pillar ◽  
Design Parameters ◽  
Deep Soil ◽  
Mine Shaft ◽  
Dynamic Prediction ◽  
Probability Integral Method ◽  
Mining Conditions ◽  
Shaft Deflection

The main shaft and auxiliary shaft in the Guotun Coal Mine underwent large deflections, with deflection values of 359 mm and 322 mm, respectively. These two deflections represent the first occurrence of such large vertical shaft deviations in the soil strata in China. The deflection problem has seriously affected the hoisting safety and lining safety and has become a serious impediment to the sustainable production of mines. Therefore, the deflection mechanism must be determined. For this purpose, based on mining subsidence theory, the spatial probability integral method and a more accurate time function were used to establish a model, called 3D dynamic prediction model, for predicting the shaft movement. The formulas for calculating the lining stress caused by coal mining were based on established models. With measured shaft deflection data, the prediction parameters for deep soil strata were calculated on the basis of an inversion analysis. A comparative analysis of measured and calculated deflection values revealed that the reason for shaft deflection in Guotun Coal Mine is the insufficient size of the protection coal pillar (PCP); namely, the design parameters of the PCP in current codes are not applicable to the deep soil strata. As a result, under the asymmetric mining conditions, mining causes the shaft to deflect without damage and under the symmetric mining conditions, mining causes the lining to fracture. The results have an extremely important significance for the prevention and control of shaft deflection, for the rational design of PCP, and for the sustainability of mine production.

scholarly journals The Porosity Dynamic Model of the Compacted Broken Coal

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xuefeng Han ◽  
Tingxiang Chu ◽  
Minggao Yu ◽  
Jiangkun Chao ◽  
Zhihui Ma ◽  
...  
Keyword(s):  
Spontaneous Combustion ◽  
Axial Stress ◽  
Fractal Theory ◽  
Dynamic Change ◽  
Strain Curve ◽  
Fractal Model ◽  
Evolution Model ◽  
Dynamic Evolution ◽  
Permeability Evolution ◽  
Loading Test

In order to study the dynamic change law of the porosity of the compacted broken coal under different axial stress loading, based on the environment of the broken and compacted coal in the gob, aiming at the influence of the porosity on the spontaneous combustion of the coal, combined with the fractal theory, the fractal model of the porosity of the broken coal is established. A self-designed “testing device for permeability evolution and spontaneous combustion characteristics of crushed coal under pressure” is used to carry out axial loading test on selected coal samples in the gob. By comparing and analyzing the calculated results of void dynamic evolution model and experimental data, it is found that the relative error of void dynamic evolution model is between 2.8% and 6.2%, which meets the engineering needs. According to the stress-strain curve, initial accumulation state parameters, fractal dimension of initial crushing, and particle size distribution, the change of porosity under different compacted conditions can be predicted by the model, which has certain significance for identifying the change of compacted broken coal porosity and analyzing the process of coal spontaneous combustion and oxidation.

scholarly journals Stability of Split-Level Gob-Side Entry in Ultra-Thick Coal Seams: A Case Study at Xiegou Mine

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 628 ◽  
Author(s):  
Junwen Zhang
Keyword(s):  
Coal Mine ◽  
Coal Pillar ◽  
Peak Stress ◽  
Coal Seams ◽  
Solid Coal ◽  
Stress Fluctuation ◽  
Pillar Mining ◽  
The Stability ◽  
Rock Specimens

Split-level longwall gob-side entry (SLGE) has been applied as a special form of small gate pillar mining (or non-coal pillar mining) in thick coal seams. The stability of the coal pillar directly affects the rationality of the layout of the SLGE. Starting from the mining-induced influence around the SLGE, this paper compares the mechanical properties of coal under different mining effects, and studies the rationality of “zero pillar” location against the Xiegou coal mine. The study shows that the key to success of the application of the SLGE is the existence of an intact zone within the triangular coal pillar in spite of double disturbances due to tunneling and coal mining extraction. Laboratory testing shows that the density and uniaxial compressive strength of rock specimens obtained from the triangular coal pillar are smaller than that from the other part of the panel which is concluded to be due to the varied degree of mining-induced influence. The numerical modeling results show that most of the triangular coal pillar is intact after extraction of the panel, and that the peak stress is located in the solid coal beyond the triangular coal pillar. The plastic zone of the triangular coal pillar is only about 1 m after the excavation of the tail gate of the next split-level panel. The physical modeling shows that the tail gate of the next panel is in the destressed zone with only a very small stress fluctuation during the extraction of the next panel. The study shows that the location of the SLGE at Xiegou coal mine is reasonable. SLGE is preferable for ultra-thick coal seams.

Detonating Gas Simulation Experiment System Based on the Dynamic ESD Model on Human Body

2011 ◽  
Vol 704-705 ◽  
pp. 407-411
Author(s):  
Xiu Jie Dong ◽  
Xu Chen ◽  
Jing Chang Zhang ◽  
Liang Zhang
Keyword(s):  
Software Design ◽  
Human Body ◽  
Coal Mine ◽  
Simulation Experiment ◽  
Dynamic Change ◽  
Mixed Gas ◽  
Gas Detonation ◽  
Experiment System ◽  
Gas Concentration ◽  
Mine Environment

Variation of dynamic electrostatic discharge (ESD) on human body that miners’ voltage,capacitance and resistance varies with the body’s dynamic change in coal mine environment is studied. A circuit model of the body’s dynamic ESD in coal mine environment is constructed. The simulation experiment system of the gas detonation by the human body ESD in coal mine is developed successfully. System principle, system hardware design and system software design is expounded. Simulation experiments with different body’s ESD model and the discharge gap has been done. Experimental results show that the system can be carried out series of experiments of the human body ESD model detonating mixed gas, it is concluded that the gas concentration that is the easiest to be detonated is about 8.7%. but not the higher gas concentration is , the more explosive is. The results provide an theoretical and experimental evidence for the safe electrostatic production and management in coal mine Keywords:simulation experiment system; dynamic ESD model ; hardware and software design ; human body capacitance

The Green Design of Bracket of Scraper Part of Coal Mine Underground Horizontal Extension Transfer Machine

2012 ◽  
Vol 591-593 ◽  
pp. 44-47 ◽  
Author(s):  
Ping Huai Mao ◽  
Li Ding ◽  
Jing Xi Li
Keyword(s):  
Coal Mine ◽  
Working Environment ◽  
Green Design ◽  
Main Bearing

Recently, transporting coal in the coal mine is poor efficiency and too costly. Coal mine underground horizontal extension transfer machine is used to transport coal faster and better. To resolve the problem how to connect the scraper conveyer with tramcar in this system, the design of the bracket has been brought up. The bracket of scraper part is the main bearing of coal mine underground horizontal extension transfer machine, and all the scraper conveyer must be fixed in the bracket. In addition, the design of the bracket of scraper part not only considers the rationality in the structure, but also considers the effect of the environment. The system works in extreme circumstances, but the green design can resolve it. It can effectively combine the choice of material, the structure of the bracket, the methods of technology with exterior styling, reflecting the human, machine of harmony with the working environment.

Sign in / Sign up

Export Citation Format

Share Document