scholarly journals Stability Analysis of Surrounding Rock in Paste Backfill Recovery of Residual Room Pillars

2019 ◽  
Vol 11 (2) ◽  
pp. 478 ◽  
Author(s):  
Nan Zhou ◽  
Hao Yan ◽  
Shuyin Jiang ◽  
Qiang Sun ◽  
Shenyang Ouyang
Keyword(s):  
Surface Deformation ◽  
Surrounding Rock ◽  
Induced Earthquakes ◽  
Mining Areas ◽  
Rock Stability ◽  
Study Results ◽  
Deformation Properties ◽  
Paste Backfill ◽  
Northern Shaanxi ◽  
Coal Pillars

A method of paste backfill recovery for residual room coal pillars is hereby proposed. The principles and processes of this method are systemically explained to address issues such as mining-induced earthquakes from spontaneous destabilization, surface subsidence, and low recovery rates. These are caused by the instability of residual coal pillars due to their spontaneous combustion in room-and-pillar mining in medium-to-small coalmines in the northern Shaanxi area. This method is based on the local abundance of surface aeolian sand and solid wastes to be used as paste-backfilling materials in coalmines in the northern Shaanxi area. Uniaxial compressive strength, bleeding rate, and slump tests were performed on paste-backfilled samples constituted at different ratios based on the types of materials involved in paste backfilling in the northern Shaanxi region, thereby helping to confirm the optimal ratios for paste-backfilling materials for the Ershike coal mine. A simulation was conducted to investigate the failure, goaf vertical stress distribution, and surface deformation properties of paste-backfilled pillars and coal pillars, where paste backfilling was used with paste-backfilling materials constituted at different compressive strengths. This was to verify the experimental results that would be obtained with paste-backfilling materials constituted at different ratios, and reveal the mechanism by which paste backfilling of residual room pillars can maintain the mine’s surrounding rock stability. These study results are of great instructive significance to the safe recovery of residual room pillars in China’s western mining areas.

scholarly journals MONITORING SOIL MOISTURE IN A COAL MINING AREA WITH MULTI-PHASE LANDSAT IMAGES

2016 ◽  
Vol XLI-B7 ◽  
pp. 537-542
Author(s):  
J. L. Kong ◽  
T. Xian ◽  
J. Yang ◽  
L. Chen ◽  
X. T. Yang
Keyword(s):  
Soil Moisture ◽  
Coal Mining ◽  
Surface Deformation ◽  
Mean Squared Error ◽  
Ground Deformation ◽  
Quadratic Model ◽  
Fissure Zone ◽  
Water Losses ◽  
Study Results ◽  
Northern Shaanxi

The coal development zone of Northern Shaanxi, China is one of the eight largest coal mines in the world, also the national energy and chemical bases. However, the coal mining leads to ground surface deformation and previous studies show that in collapse fissure zone soil water losses almost 50% compared with non-fissure zone. The main objective of this study is to develop a retrieval model that is reliable and sensitive to soil moisture in the whole coal mining zone of Northern Shaanxi based upon the soil sample parameters collected from <i>in situ</i> site investigation, spectral data gathered simultaneously and the images of Landsat7 ETM. The model uses different phases of Landsat data to retrieve soil moisture and analyze the patterns of spatial and temporal variations of soil moisture caused by ground deformation in the coal mining areas. The study indicated that band4 of Landsat7 ETM is the most sensitive band for soil moisture retrieval using the spectrum method. The quadratic model developed by remote sensing reflectance (Rrs4) (corresponding to the band4) is the best pattern with the correlation coefficient of 0.858 between the observed and the estimated soil moisture. Two-phase Landsat7 ETM data of 2002 and 2009 and one phase Landsat8 OLI data of 2015 for the study area were selected to retrieve soil moisture information. The result showed that the mean relative error was 35.16% and the root-mean-squared error (RMSE) was 0.58%. The changes of the spatial distribution of inversed soil moisture revealed that the trend of soil moisture contents of the study area was in general being gradually reduced from 2002 to 2015. The study results can serve as the baseline for monitoring environmental impacts on soil moisture in the regions due to coal mining.

scholarly journals Measurement and Analysis of Roadway Deformation and Stress under Mining-Induced Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jianfeng Cui ◽  
Weijun Wang ◽  
Qian Jia ◽  
Gang Peng ◽  
Hai Wu
Keyword(s):  
Surface Deformation ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Mining Operations ◽  
Absolute Displacement ◽  
Induced Stress ◽  
High Side ◽  
Roadway Stability ◽  
The Absolute ◽  
Coal Pillars

Small coal pillars, which are used to protect roadways, have a significant influence on mining operations and roadway stability and safety. Consequently, the optimal width of coal pillars that provides suitable performance under mining-induced stress must be determined accurately. Based on the deformation data of the surrounding rock along the gob roadway of the 13318 working face in Xieqiao Coal Mine, we analyzed the surface deformation data of the roadway and the displacement of the deep surrounding rock of the roadway under the action of mining-induced stress herein. The separation fractures of the low side of the roadway can be divided into four zones: 0–2 m, 2–5 m, 5–9 m, and 9–11 m. The absolute displacement of the surrounding rock relative to the center of the roadway in the 0–2 m zone was large, and the displacement region in the side of the roadway extended from 0 m to 11 m. The separation fractures of the high side of the roadway can be divided into three zones: 0–3 m, 3–5 m, and 5–5.5 m. The absolute displacement of the surrounding rock relative to the center of the roadway in the 0–3 m zone was large, whereas the deformation separation of the coal pillar was small. The surrounding rock in the 5–5.5 m zone also exhibited absolute displacement relative to the center of the roadway. Furthermore, the stress increased faster on the low side of the roadway than the high side; the core stress region on the high side occurred at approximately 3 m, whereas that on the low side occurred at approximately 8 m. The findings obtained herein can help determine the optimal preset width of small pillars.

scholarly journals MONITORING SOIL MOISTURE IN A COAL MINING AREA WITH MULTI-PHASE LANDSAT IMAGES

2016 ◽  
Vol XLI-B7 ◽  
pp. 537-542 ◽  
Author(s):  
J. L. Kong ◽  
T. Xian ◽  
J. Yang ◽  
L. Chen ◽  
X. T. Yang
Keyword(s):  
Soil Moisture ◽  
Coal Mining ◽  
Surface Deformation ◽  
Mean Squared Error ◽  
Ground Deformation ◽  
Quadratic Model ◽  
Fissure Zone ◽  
Water Losses ◽  
Study Results ◽  
Northern Shaanxi

The coal development zone of Northern Shaanxi, China is one of the eight largest coal mines in the world, also the national energy and chemical bases. However, the coal mining leads to ground surface deformation and previous studies show that in collapse fissure zone soil water losses almost 50% compared with non-fissure zone. The main objective of this study is to develop a retrieval model that is reliable and sensitive to soil moisture in the whole coal mining zone of Northern Shaanxi based upon the soil sample parameters collected from &lt;i&gt;in situ&lt;/i&gt; site investigation, spectral data gathered simultaneously and the images of Landsat7 ETM. The model uses different phases of Landsat data to retrieve soil moisture and analyze the patterns of spatial and temporal variations of soil moisture caused by ground deformation in the coal mining areas. The study indicated that band4 of Landsat7 ETM is the most sensitive band for soil moisture retrieval using the spectrum method. The quadratic model developed by remote sensing reflectance (Rrs4) (corresponding to the band4) is the best pattern with the correlation coefficient of 0.858 between the observed and the estimated soil moisture. Two-phase Landsat7 ETM data of 2002 and 2009 and one phase Landsat8 OLI data of 2015 for the study area were selected to retrieve soil moisture information. The result showed that the mean relative error was 35.16% and the root-mean-squared error (RMSE) was 0.58%. The changes of the spatial distribution of inversed soil moisture revealed that the trend of soil moisture contents of the study area was in general being gradually reduced from 2002 to 2015. The study results can serve as the baseline for monitoring environmental impacts on soil moisture in the regions due to coal mining.

scholarly journals Multifunctional Activities of Gold Nanoparticles Biosynthesized Using Bacteria Isolated from Mining Areas

2021 ◽  
Vol 11 (8) ◽  
pp. 3670
Author(s):  
Chih-Yu Chen ◽  
Yung-Chu Chang ◽  
Teh-Hua Tsai ◽  
Man-Hai Liu ◽  
Ying-Chien Chung
Keyword(s):  
Gold Nanoparticles ◽  
Mining Area ◽  
Synthesis Process ◽  
Average Particle ◽  
Bifidobacterium Lactis ◽  
E Coli ◽  
Mining Areas ◽  
Skin Cells ◽  
Study Results ◽  
Antityrosinase Activity

Research on gold nanoparticles (AuNPs) has often focused on their physical, chemical, and crystalline characteristics. Commercial AuNPs have been applied in the diverse fields of biomedicine, catalysis, photovoltaics, and sensing. In this study, we explored the various activities of AuNPs to widen their applicability. This paper presents a simple and rapid synthesis process of AuNPs with bacteria isolated from a gold mining area. We also investigated the optimization of reaction parameters for AuNP synthesis. The study results revealed that among the isolated strains, Bifidobacterium lactis and Escherichia coli demonstrated the highest capabilities of AuNP synthesis. The optimal pH values for AuNP synthesis by B. lactis (BLAuNPs) and E. coli (ECAuNPs) were 5.0 for 72 h of incubation and 8.0 for 24 h of incubation. The average particle sizes of ECAuNPs and BLAuNPs were 4.2 and 5.6 nm, respectively. Furthermore, these biogenic AuNPs were found to be stable with no aggregation after 3 months of storage. BLAuNPs and ECAuNPs exhibited high levels of antimicrobial, antioxidant, photocatalytic, and antityrosinase activity. Moreover, they were noncytotoxic to skin cells even at 100% melanin inhibitory concentrations. Considering the demonstrated multifunctional activities of AuNPs, BLAuNPs and ECAuNPs have promising potential for commercialization.

scholarly journals Study on instability failure mode and monitoring early warning standard of surrounding rock in fully weathered argillaceous sandstone section of large section tunnel

2019 ◽  
Vol 136 ◽  
pp. 04023
Author(s):  
Ming Zhao ◽  
Ke Li ◽  
Hong Yan Guo ◽  
KaiCheng Hua
Keyword(s):  
Limit State ◽  
Stable State ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Large Section ◽  
Rock Stability ◽  
Geological Conditions ◽  
Construction Step ◽  
The Face ◽  
The Stability

Based on the special geological conditions of a tunnel in Qingyuan section of Huizhou-Zhanzhou Expressway, FLAC3d numerical simulation software is used to simulate the rheological properties and instability of surrounding rock in large-section fully weathered sandstone section, and the stability and loss of surrounding rock are analyzed. The deformation of the dome and the face at steady state is analyzed. It is found that: 1) when the surrounding rock is in a stable state, the deformation curve of the dome is smooth. When the surrounding rock of the face is unstable, the front of the face appears ahead. Deformation should be first strengthened on the surrounding rock in front of the face. 2) The arched foot is an important part of the instability of the surrounding rock. In order to prevent the expansion of the collapsed part, the arched part should be reinforced. 3) In order to obtain the limit state of surrounding rock stability, the strength of surrounding rock is reduced, and the strength reduction coefficient corresponding to the displacement sudden point is taken as the safety factor of rock stability around the hole, and the stability safety coefficients of surrounding rock of each construction step are greater than 1.2. 4) The dynamic standard values of deformation control in the whole construction stage are obtained by analyzing the deformation curves of each data monitoring point with time in the corresponding time period of each construction step.

Application of ABAQUS in Surrounding Rock Stability Analysis of Shallow Large Cross-Section Tunnel

2015 ◽  
Vol 777 ◽  
pp. 8-12 ◽  
Author(s):  
Lin Zhen Cai ◽  
Cheng Liang Zhang
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Strong Support ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Tunnel Excavation ◽  
Rock Stability ◽  
Rock Bolting ◽  
Excavation Support ◽  
The Stability

HuJiaDi tunnel construction of Dai Gong highway is troublesome, the surrounding-rock mass give priority to full to strong weathering basalt, surrounding rock integrity is poor, weak self-stability of surrounding rock, and tunnel is prone to collapse. In order to reduce disturbance, taking advantage of the ability of rock mass, excavation adopt the method of "more steps, short footage and strong support". The excavation method using three steps excavation, The excavation footage is about 1.2 ~ 1.5 m; The surrounding rock bolting system still produce a large deformation after completion of the first support construction, it shows that the adopted support intensity cannot guarantee the stability of the tunnel engineering. Using ABAQUS to simulate tunnel excavation support, optimizing the support parameters of the tunnel, conducting comparative analysis with Monitoring and Measuring and numerical simulation results, it shows that the displacement - time curves have a certain consistency in numerical simulation of ABAQUS and Monitoring and Measuring.

Application of Catastrophe Theory in Surrounding Rock Stability

2013 ◽  
Vol 712-715 ◽  
pp. 974-978
Author(s):  
Din Ge Kong ◽  
Kai Hu
Keyword(s):  
Catastrophe Theory ◽  
Surrounding Rock ◽  
Underground Engineering ◽  
Rock System ◽  
Instability Problem ◽  
Rock Stability ◽  
Highly Nonlinear ◽  
Practical Engineering ◽  
Simplified Mechanical Model ◽  
Catastrophic Model

Surrounding rock system of underground engineering is highly nonlinear, and there is no unified cognition for its stability criteria. Introduces the basic principle of catastrophe theory, focusing on the cusp catastrophic model, build a simplified mechanical model for the surrounding rock, and the instability of surrounding rock of the cusp catastrophic model is obtained. In practical engineering, it is show that catastrophe theory is an effective method to study the instability problem of the tunnel.

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