scholarly journals Physical Model Experimental Study on the Coalface Overburden Movement Law on the End-slope of an Open-pit Mine

2022 ◽  
Author(s):  
xinpin ding ◽  
Fengming Li ◽  
Zhenwei Wang ◽  
Sheng Sang ◽  
Mingming Cao
Keyword(s):  
Rock Mass ◽  
Coal Mining ◽  
Coal Pillar ◽  
Slope Deformation ◽  
Open Pit ◽  
Deep Part ◽  
Slope Surface ◽  
Deformation And Failure ◽  
Coal Pillars ◽  
Slope Rock

Abstract Due to technology and safety limitations, the amount of coal resources overlying slopes in open pit coal mines is immense. In recent years, this problem has gradually attracted the attention of researchers. How to realize the efficient recovery of the side overburden resources with the premise of ensuring the stability and safety of the slope has become an important topic for the development of opencast mining technology in China. To study the yield failure characteristics of coal pillars and the rock mass migration law of the end slope mining field under the mining condition of the end slope shearer, 2D/3D, integrated, simulation experimental equipment is developed based on similarity theory and efficient region theory. This equipment overcomes the technical problem that the internal failure of the rock mass is invisible and that deformation data are not easily obtained during the simulation of end slope coal mining on an existing experimental platform. Based on the engineering geological conditions of the Ordos mining area in China, a typical engineering geological model of the slope near the horizontal condition is constructed to simulate the process “formation of mining cave group -failure of support coal pillars - instability of slope rock mass”. Based on laser positioning technology and multiangle, oblique photography technology, a panoramic phase 3D laser scanner, high-resolution digital camera and deep space micromonitoring system are comprehensively employed to carry out the whole process tracking monitoring and analysis of the deformation and failure of the supporting coal pillars and slope rock mass. The experiment is verified by numerical simulation. The results show that under the experimental conditions, with an increase in mining cave depth, the vertical stress of the supporting coal pillar increases linearly. At a certain distance before reaching the end of the mining cave, the peak value is reached. At this time, the depth continues to increase, and the stress value decreases sharply. The vertical stress gradually decreases to the original rock stress after a certain distance beyond the end of the mining cave. A certain length of supporting coal pillar from the end of the mining cave will never collapse, which is approximately 2.5~3 times the width of the mining cave. The triggering condition of slope deformation and failure is under the combined action of dynamic and static loads. The actual stress of the supporting coal pillar in the deep part of the geometric centre along the slope of the mining cave group is greater than the ultimate stress, and then large discontinuous deformation of multiple adjacent coal pillars around the central coal pillar is caused by compressive shear failure. The boundary of the final collapse plane range of the roadway group is approximately a closed curve formed by two paraboloids, which are axisymmetric with the No. Ⅳ coal pillar and open opposite. The parabola opening in the shallow part of the slope area is small, and the parabola opening in the deep part of the slope area is large. There is a significant space-time correspondence between the failure of supporting coal pillars and the deformation of the slope surface. According to the failure process of the rock mass structure and the movement and deformation characteristics of the slope surface, the slope after failure can be divided into three areas, and the upper part of the slope is the key area of deformation and instability of the overlying rock mass in the end-slope mining field. The research results provide a theoretical basis for scientific monitoring and stability control of slope deformation coal mining conditions in open-pit mines.

scholarly journals Variable Weight Matter–Element Extension Model for the Stability Classification of Slope Rock Mass

Mathematics ◽  
2021 ◽  
Vol 9 (21) ◽  
pp. 2807
Author(s):  
Shan Yang ◽  
Zitong Xu ◽  
Kaijun Su
Keyword(s):  
Rock Mass ◽  
Classification Criteria ◽  
Evaluation Index ◽  
Open Pit ◽  
Constant Weight ◽  
Extension Model ◽  
Variable Weight ◽  
Slope Rock ◽  
The Stability ◽  
Index Value

The slope stability in an open-pit mine is closely related to the production safety and economic benefit of the mine. As a result of the increase in the number and scale of mine slopes, slope instability is frequently encountered in mines. Therefore, it is of scientific and social significance to strengthen the study of the stability of the slope rock mass. To accurately classify the stability of the slope rock mass in an open-pit mine, a new stability evaluation model of the slope rock mass was established based on variable weight and matter–element extension theory. First, based on the main evaluation indexes of geology, the environment, and engineering, the stability evaluation index system of the slope rock mass was constructed using the corresponding classification criteria of the evaluation index. Second, the constant weight of the evaluation index value was calculated using extremum entropy theory, and variable weight theory was used to optimize the constant weight to obtain the variable weight of the evaluation index value. Based on matter–element extension theory, the comprehensive correlation between the upper and lower limit indexes in the classification criteria and each classification was calculated, in addition to the comprehensive correlation between the rock mass indexes and the stability grade of each slope. Finally, the grade variable method was used to calculate the grade variable interval corresponding to the classification criteria of the evaluation index and the grade variable value of each slope rock mass, so as to determine the stability grade of the slope rock. The comparison results showed that the classification results of the proposed model are in line with engineering practice, and more accurate than those of the hierarchical-extension model and the multi-level unascertained measure-set pair analysis model.

scholarly journals Study on Protective Coal Pillar Size Design for Ultra High Voltage Line Tower Mining in Mountain Areas

Designs ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 20
Author(s):  
Feiya Xu ◽  
Wenbing Guo ◽  
Jianli Li
Keyword(s):  
Coal Mining ◽  
High Voltage ◽  
Coal Pillar ◽  
Vertical Line ◽  
Mountain Areas ◽  
Pillar Design ◽  
Critical Deformation ◽  
Line Method ◽  
Coal Pillars ◽  
Ultra High Voltage

High voltage line towers in mining areas are sensitive to surface deformation caused by mining. Protective coal pillar design for high voltage towers is one of the commonly-used technical measures. Aiming to solve the coal mining safety problem under the Ultra High Voltage transmission line in Sihe Coal Mine of Shanxi Province, the angle and size of protective coal pillars with the vertical line method were analyzed in this paper. The effect of additional displacement caused by landslide or slippage mining in mountain areas and repeated mining was considered. Based on the principle of the vertical line method, the protective coal pillar range and size were calculated. The amount of coal deposited in coal pillars for high voltage line towers was compared and analyzed between the vertical line method and the linear structure method. The results showed that the angle of critical deformation decreased by 2~10° caused by slippage due to mining in a mountainous area, and the angle in the uphill direction of building decreased more than that in the downhill direction; when multi-seams were mined repeatedly, the angle of critical deformation in the lower seam coal mining was reduced by 5~10° compared with that of the upper seam. The protective coal pillar design with the vertical line method can protect the high voltage line towers more effectively, and the amount of protective coal pillars with the vertical line method was 5.8 million tons less, which avoided the waste of coal resources.

Research of New Filling and Mining Technology Using Waste Rocks in Steep Coal Seams

2012 ◽  
Vol 204-208 ◽  
pp. 1395-1400
Author(s):  
Chuan Wei Zang ◽  
Chuan Le Ma ◽  
Xue An Zhuang
Keyword(s):  
Coal Mining ◽  
Coal Pillar ◽  
Recovery Ratio ◽  
Mining Method ◽  
Coal Seams ◽  
Coal Recovery ◽  
Waste Rocks ◽  
Filling Method ◽  
Gob Area ◽  
Coal Pillars

During the extraction of steeply inclined coal seams, the coal recovery ratio is low be-cause of the coal pillar loss and the production of waste rock is high due to lots of rock roadways which causes serious environmental pollution. This status is conflicted with the strategy of Clean Coal Mining and Green Coal Mining in China, so it is necessary to develop new coal mining method. In this paper, Downward Stratified Gangue Self-filling Method on the Flexible Shield (DSGSMFS) is put forward first. It means that the coal face is lain horizontally and advances along the dip; the flexible shield is used to separate the gob area; the waste rocks are self-filled downward to the top the shield; the coal is broken by drilling and blasting method under the shield, and the broken coal is transported by the electrical winch and the scraping mucker; the flexible shield moves downward automatically by the weight of itself and waste rocks. Field test shows that the strata displacement is effectively controlled by using DSGSMFS, so some coal pillars are recovered; as a result the problem of large quantity gangue and low coal recovery ratio in steep coal seam is solved. DSGSMFS is proved to be a new hopeful and effective coal green mining method.

scholarly journals A physical model study of surrounding rock failure near a fault under the influence of footwall coal mining

2020 ◽  
Author(s):  
Shukun Zhang ◽  
Lu Lu ◽  
Ziming Wang ◽  
Shuda Wang
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Hanging Wall ◽  
Coal Pillar ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Pillar Width ◽  
Model Study ◽  
Working Face ◽  
Coal Pillars

AbstractA study of the deformation of the surrounding rock and coal pillars near a fault under the influence of mining is conducted on a physical model for the design of coal pillars to support and maintain the roofs of adjacent fault roadways. This research is based on the 15101 mining face in the Baiyangling Coal Mine, Shanxi, China, and uses simulation tests similar to digital speckle test technology to analyse the displacement, strain and vertical stress fields of surrounding rocks near faults to determine the influence of the coal pillar width. The results are as follows. The surrounding rock of the roadway roof fails to form a balance hinge for the massive rock mass. The vertical displacement, vertical strain and other deformation of the surrounding rock near the fault increase steeply as the coal pillar width decreases. The steep increase in deformation corresponds to a coal pillar width of 10 m. When the coal pillar width is 7.5 m, the pressure on the surrounding rock near the footwall of the fault suddenly increases, while the pressure on the hanging wall near the fault increases by only 0.35 MPa. The stress of the rock mass of the hanging wall is not completely shielded by the fault, and part of the load disturbance is still transmitted to the hanging wall via friction. The width of the fault coal pillars at the 15101 working face is determined to be 7.5 m, and the monitoring data verify the rationality of the fault coal pillars.

Study on Optimization Method of the Slope Angle Design for Open-Pit Mine

2013 ◽  
Vol 734-737 ◽  
pp. 656-660 ◽  
Author(s):  
Shao Jie Feng ◽  
Shi Guo Sun ◽  
Ya Nan Yi
Keyword(s):  
Rock Mass ◽  
Optimization Design ◽  
Slope Angle ◽  
Optimization Method ◽  
Open Pit Mine ◽  
Mine Safety ◽  
Open Pit ◽  
Resource Exploitation ◽  
Original Design ◽  
Slope Rock

The critical slip field theory is applied to optimization design of the slope angle. An intelligent matching optimization of the slope angle design is carried out based on the strata distribution, mechanics parameters of rock mass and a given security reserve. That is the implementation of the maximum allowable slope angle of slope rock mass under the given conditions. Optimized by the final highwall of Buzhaoba Open-Pit Mine, the overall slope angle increased 3°compared to the original design. Which implement the optimum slope angle of final highwall, modified the shortcoming in the original design and ensure the maximization of mine safety and the resource exploitation.

scholarly journals Research on stress release for the gob-side roadway using the roof-cutting technology with a chainsaw arm

2020 ◽  
Vol 7 (3) ◽  
pp. 191663
Author(s):  
Yang Tai ◽  
Bin Yu ◽  
Binwei Xia ◽  
Zhao Li ◽  
Hongchu Xia
Keyword(s):  
Numerical Analysis ◽  
Coal Pillar ◽  
Deformation And Failure ◽  
Hard Roof ◽  
Working Face ◽  
Stress Relieving ◽  
Cutting Experiment ◽  
Pillar Mining ◽  
Coal Pillars ◽  
Cutting Height

The narrow pillar mining method is widely adopted for working faces in coal mines. However, in cases of an overlying hard roof, a suspended triangle roof plate or a cantilever will be formed near the goaf. At this point, the coal pillar extrusion and serious deformation will occur in the gob-side roadway. In order to mitigate the problem, the roof-cutting technology with a chainsaw arm and its equipment have been developed. In this paper, based on the analysis of deformation and failure characteristics of 2312 roadway, which is close to the goaf of 2311 working face in Tashan Coal, the roof-cutting technology with a chainsaw arm was chosen to be applied in 2311 roadway. Then, the roof-cutting process and the load acting on the coal pillar were discussed and analysed. A numerical model was established to analyse the stress releasing effects after roof cutting. Moreover, the roof-cutting height and the support parameters of the roadway were optimized through numerical analysis and the results manifested that the roof cutting was the most effective when the roof-cutting height was 6.4 m. After roof cutting, the vertical stresses within the coal pillars were lowered by about 25.0%. Finally, the roof-cutting experiment was carried out in the 2311 roadway in Tashan Coal Mine. The on-site roof-cutting depth was 6.4 m and the roof-cutting width was 42 mm guided by the numerical analysis. To verify the stress-relieving effects, the borehole stress meters were applied to monitor the peak advancing stresses of narrow pillars at various depths. The measured results indicated that the peak advancing stresses decreased by 22.8% on average, and therefore, roof cutting and stress releasing effects were achieved.

Study on Stability and Failure Characteristics of the Slope in Transition from Open-Pit to Underground Mining by Structural Geology

2012 ◽  
Vol 170-173 ◽  
pp. 932-936 ◽  
Author(s):  
Yun Fei Wang ◽  
Fang Cui
Keyword(s):  
Underground Mining ◽  
Structural Features ◽  
Open Pit ◽  
Slope Surface ◽  
Failure Characteristics ◽  
Structure Surface ◽  
Engineering Geological Zoning ◽  
Slope Rock ◽  
The Stability ◽  
The Impact

According to the impact on the slope characteristics, characteristics of underground ore occurrence, underground ore mining, the open pit slope can be separated by engineering geological zoning. After analyzed the factors that affect the stability of the slope rock, such as the combination relation between the slope surface and the structure surface, deposits of occurrence conditions, structural features and so on. The combination of cutting and under the action of the form may be made of the damage and determine the stability of the various partitions.

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