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.

scholarly journals Determination of cyclic filling length in gob-side entry retained with roadside filling and its application

2020 ◽  
Author(s):  
Zizheng Zhang ◽  
Jianbiao Bai ◽  
Xianyang Yu ◽  
Weijian Yu ◽  
Min Deng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Difference Method ◽  
Suggested Method ◽  
Stress Difference ◽  
Thick Coal Seam ◽  
Mechanics Model ◽  
Working Face ◽  
Geological Conditions ◽  
The Relationship

Abstract Gob-side entry retained with roadside filling (GER-RF) plays a key role in achieving coal mining without pillar and improving the coal resource recovery rate. Since there are few reports on the cyclic filling length of GER-RF, a method based on the stress difference method is proposed to determine the cyclic filling length of GER-RF. Firstly, a stability analysis mechanics model of the immediate roof above roadside filling area in GER was established, then the relationship between the roof stress distribution and the unsupported roof length was obtained by the stress difference method. According to the roof stability above roadside filling area based on the relationship between the roof stress and its tensile strength, the maximum unsupported roof length and rational cyclic filling length of GER-RF. Combined with the geological conditions of the 1103 thin coal seam working face of Heilong Coal Mine and the geological conditions of the 1301 thick coal seam working face of Licun Coal Mine, this suggested method was applied to determine that the rational cyclic filling lengths of GER-RF were 2.4 m and 3.2 m, respectively. Field trial tests show that the suggested method can effectively control the surrounding rock deformation along with rational road-in support and roadside support, and improve the filling and construction speed.

Relationship between Methane Emission and Strata Behavior at Island Coal Face

2012 ◽  
Vol 524-527 ◽  
pp. 662-667
Author(s):  
Xin Xian Zhai ◽  
Fu Lin Wang
Keyword(s):  
Coal Mine ◽  
Methane Emission ◽  
Emission Rate ◽  
Main Roof ◽  
Control Measures ◽  
Emission Rates ◽  
Coal Face ◽  
Coal Wall ◽  
Strata Behavior ◽  
Methane Emission Rate

According to the practical conditions of the island coal face in No.2 Coal Mine of Pingdingshan Coal Company Ltd., China, the strata behaviors and methane emission were monitored and their two relationships were analyzed. The results indicate that strata behavior at coal face affects its methane emission rates at coal wall and goaf，which the quantity of methane emission rate at coal face is largely increasing after main roof weighting. So through the monitor of periodic roof weighting time, larger methane emission rate at coal face can be predicted. Then the related methane control measures can be taken timely.

scholarly journals Determination of Cyclic Filling Length in Gob-Side Entry Retained with Roadside Filling and Its Application

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Zizheng Zhang ◽  
Jinlin Xin ◽  
Jianbiao Bai ◽  
Xianyang Yu ◽  
Weijian Yu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Difference Method ◽  
Suggested Method ◽  
Stress Difference ◽  
Thick Coal Seam ◽  
Mechanics Model ◽  
Working Face ◽  
Geological Conditions ◽  
The Relationship

Gob-side entry retained with roadside filling (GER-RF) plays a key role in achieving coal mining without pillar and improving the coal resource recovery rate. Since there are few reports on the cyclic filling length of GER-RF, a method based on the stress difference method is proposed to determine the cyclic filling length of GER-RF. Firstly, a stability analysis mechanics model of the immediate roof above the roadside filling area was established, and then, the relationship between the roof stress distribution and the unsupported roof length was obtained by the stress difference method. According to the roof stability above the roadside filling area based on the relationship between the roof stress and its tensile strength, the maximum unsupported roof length and rational cyclic filling length were determined. Combined with the geological conditions of the 1103 thin coal seam working face of Heilong Coal Mine and the 1301 thick coal seam working face of Licun Coal Mine, the suggested method was applied to determine that the rational cyclic filling lengths were 2.4 m and 3.2 m, respectively. Field trial tests show that the suggested method can effectively control the surrounding rock deformation along with rational road-in support and roadside support and improve the filling and construction speed.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

scholarly journals Substantiation of Safe Conditions During Undermining of Hydraulic Waste Disposal

2018 ◽  
Vol 41 ◽  
pp. 01007
Author(s):  
Yuriy Kutepov ◽  
Aleksandr Mironov ◽  
Maksim Sablin ◽  
Elena Borger
Keyword(s):  
Rock Mass ◽  
Waste Disposal ◽  
Coal Mine ◽  
Water Body ◽  
Water Inflow ◽  
Open Pit ◽  
Coal Seams ◽  
Geological Conditions ◽  
Mine Workings ◽  
Mine Dump

This article considers mining and geological conditions of the site “Blagodatny” of the mine named after A.D. Ruban located underneaththe old open pit coal mine and the hydraulic-mine dump. The potentially dangerous zones in the undermined rock mass have been identified based onthe conditions of formation of water inflow into mine workings. Safe depthof coal seams mining has been calculated depending on the type of water body – the hydraulic-mine dump.

scholarly journals Failure Mechanisms and the Control of a Longwall Face with a Large Mining Height within a Shallow-Buried Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Haijun Wang ◽  
Yingjie Liu ◽  
Yuesong Tang ◽  
Hao Gong ◽  
Guoliang Xu
Keyword(s):  
Tensile Stress ◽  
Coal Mine ◽  
Horizontal Displacement ◽  
Longwall Face ◽  
Mining Equipment ◽  
Coal Seams ◽  
Increasing Trend ◽  
Support Force ◽  
Coal Wall ◽  
Mining Height

The capabilities of mining equipment and technology in China have been improving rapidly in recent years. Correspondingly, in the western part of the country, the mining heights of longwall faces in shallow-buried coal seams have shown an increasing trend, resulting in enhanced mining efficiency. However, the problems associated with the possible failure of the coal wall then increase and remain a serious difficulty, restricting safe and efficient mining operations. In the present study, the 12401 longwall face of the Shangwan Coal Mine, Inner Mongolia, China, with a mining height of 8.8 m, is taken as an example to study the mechanisms underlying failure phenomena of coal walls and their control methods. Our results show that the failure region inward of the longwall face is small in shallow-buried coal seams, and the damage degree of the exposed coal wall is low. The medium and higher sections of the coal wall display a dynamic failure mode, while the broken coal blocks, given their initial speed, threaten the safety of coal miners. A mechanical model was developed, from which the conditions for tensile failure and structural instability are deduced. Horizontal displacement in the lower part of the coal wall is small, where no tensile stress emerges. On the other hand, in the intermediate and higher parts of the coal wall, horizontal displacement is relatively large. In addition, tensile stress increases first with increasing distance from the floor and then decreases to zero. Experiments using physical models representing different mining heights have been carried out and showed that the horizontal displacement increases from 6 to 12 mm and load-bearing capacity decreases from 20 to 7.9 kN when the coal wall increases in height from 3 to 9 m. Furthermore, failure depth and failure height show an increasing trend. It is therefore proposed that a large initial support force, large maximum support force, large support stiffness, and large support height of a coal wall-protecting guard are required for the improved stability of high coal walls, which operate well in the Shangwan coal mine.

Study on Stability for Intersection of Deep Soft Rock Roadway

2011 ◽  
Vol 243-249 ◽  
pp. 2666-2669
Author(s):  
Zhan Jin Li ◽  
Yang Zhang ◽  
Xue Li Zhao
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Intersection Problem ◽  
The Third ◽  
Geological Conditions ◽  
Control Stability ◽  
Soft Rock Roadway ◽  
Crossing Point ◽  
Coupling Support ◽  
Rock Roadway

With the depth increasing continuously, more complicated of geological conditions, will make intersection in deep soft rock roadway is very difficult to support. In order to solve the intersection problem of difficult to support, combined with the third levels of the Fifth Coal Mine of Hemei, the coupling supporting design—anchor-mesh-cable + truss to control stability of crossing point—is proposed. Based software of FLAC3D, simulate the program applicable in deep soft rock roadway intersection. Application results show that the coupling support technology of anchor-mesh-cable + truss can effectively control the deformation of intersection in deep soft rock roadway.

Coal Mine Hydraulic Fracturing Underground Drainage Research and Engineering Application

2017 ◽  
Vol 863 ◽  
pp. 334-341
Author(s):  
Jun Hui Fu ◽  
Guang Cai Wen ◽  
Fu Jin Lin ◽  
Hai Tao Sun ◽  
Ri Fu Li ◽  
...  
Keyword(s):  
Stress State ◽  
Hydraulic Fracturing ◽  
Coal Mine ◽  
Engineering Application ◽  
Fracture Morphology ◽  
Plane Stress State ◽  
Theoretical Formula ◽  
Test Results ◽  
Breakdown Pressure ◽  
Elastic Mechanics

Using elastic mechanics and fracture mechanics, analyzing the coal seam hydraulic fracturing breakdown pressure, given its theoretical formula. According to hydraulic fracturing stress status, given the form of two typical hydraulic fracture morphology. Analyzing hydraulic fracturing highly elliptical shape. The displacement field in plane stress state is given, and the theoretical formula of fracturing radius of hydraulic fracturing is deduced. The fracturing technology of underground fracturing is presented, and the fracturing location and fracturing parameters are determined. In Sihe Coal Mine conducted fracturing test, the test results showed that: the average of drainage volume of fracturing hole improved 4.4 times compared with non-pressed-hole. The extraction compliance time is reduced by 38%. Roadway tunneling speed was improved by 15%. It can solve the problem of gas overrun in roadway excavation well, and has a good application and popularization value.

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 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.

Sign in / Sign up

Export Citation Format

Share Document