scholarly journals On-Site Monitoring for the Stability Evaluation of a Highway Tunnel above Goaves of Multi-Layer Coal Seams

2021 ◽  
Vol 11 (16) ◽  
pp. 7383
Author(s):  
Guangtao Cai ◽  
Wanghua Sui ◽  
Shenglin Wu ◽  
Jilin Wang ◽  
Jiaxing Chen
Keyword(s):  
Coal Seam ◽  
Evaluation Method ◽  
Safety Evaluation ◽  
Shanxi Province ◽  
Stability Evaluation ◽  
Coal Seams ◽  
Highway Tunnel ◽  
Site Monitoring ◽  
The Stability ◽  
The Individual

This paper presents the on-site monitoring of a medium–long highway tunnel constructed above a goaf of a multi-layer coal seam, in order to evaluate and maintain safety during operation. The case study of the Tianzimiao medium–long highway tunnel in Shanxi province was conducted above a goaf of a multi-layer coal seam with typical geological and engineering conditions in China, where a total of four coal seams (seam no. 3, 8, 12, and 15) were mined out with a total thickness of up to 11 m. Methods including data collection, engineering geological survey, drilling, geophysical prospecting, testing, and on-site monitoring were adopted, and a geo-mechanical model was established to conduct the research. Stratified monitoring was applied to investigate the individual settlement and deformation of the four layers of the goaf below, and a prediction of the possible deformation in tunnel floor ground was made based on the stratified measurements. The settlement of the tunnel sidewall, the internal stress in the fractured zone of the surrounding rock, and the deformation above the tunnel entrance were also monitored, and the monitoring data were compared with the numerical simulation results for the safety evaluation of the tunnel. The results show that the current tunnel deformation values and trend are both within the safety scope of the evaluation and prediction. The stability evaluation method for the multi-layer goaf used in this paper and the long-term on-site monitoring and timely feedback during operation is helpful to ensure the safe use of the tunnels above the goaves of multi-layer thick coal seams.

scholarly journals Stability Evaluation Method of Hole Wall for Bored Pile under Blasting Impact

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 79
Author(s):  
Qiuwei Yang ◽  
Zhikun Ba ◽  
Zhuo Zhao ◽  
Xi Peng ◽  
Yun Sun
Keyword(s):  
Pile Foundation ◽  
Evaluation Method ◽  
Impact Load ◽  
Stability Evaluation ◽  
Foundation Construction ◽  
Concentration Problem ◽  
Hole Wall ◽  
Failure Theory ◽  
Collapse Failure ◽  
The Stability

Blasting impact load may be encountered during the construction of some pile foundation projects. Due to the effect of blasting impact, hole collapse can easily occur in the hole-forming stage of pile foundation construction. In order to prevent hole collapse, it is very necessary to evaluate the stability of a pile hole wall before pile foundation construction. The calculation of hole collapse can usually be attributed to an axisymmetric circular hole stress concentration problem. However, the existing collapse failure theory of pile hole hardly considers the effect of blasting impact load. In view of this, this paper proposes the stability evaluation method of a pile hole wall under blasting impact. Compared with the existing collapse failure theory, the proposed method fully considers the effect of blasting impact stress. Using Mohr–Coulomb strength theory and symmetry analysis, the strength condition of collapse failure is established in this work for accurate evaluation of the stability of a hole wall. The proposed stability evaluation method is demonstrated by a pile foundation construction project of a bridge. Moreover, a shaking table test on the pile hole model was performed to verify the proposed method by experimental data. The results indicate the effectiveness and usability of the proposed method. The proposed method provides a feasible way for the stability analysis of a pile hole wall under blasting impact.

scholarly journals Surrounding Rock Movement of Steeply Dipping Coal Seam Using Backfill Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wenyu Lv ◽  
Kai Guo ◽  
Jianhao Yu ◽  
Xufeng Du ◽  
Kun Feng
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Surrounding Rock ◽  
Maximum Deflection ◽  
Coal Seams ◽  
Physical Similarity ◽  
Working Face ◽  
Rock Structure ◽  
Backfill Mining ◽  
The Stability

The movement of the overlying strata in steeply dipping coal seams is complex, and the deformation of roof rock beam is obvious. In general, the backfill mining method can improve the stability of the surrounding rock effectively. In this study, the 645 working face of the tested mine is used as a prototype to establish the mechanical model of the inclined roof beam using the sloping flexible shield support backfilling method in a steeply dipping coal seam, and the deflection equation is derived to obtain the roof damage structure and the maximum deflection position of the roof beam. Finally, numerical simulation and physical similarity simulation experiments are carried out to study the stability of the surrounding rock structure under backfilling mining in steeply dipping coal seams. The results show the following: (1) With the support of the gangue filling body, the inclined roof beam has smaller roof subsidence, and the maximum deflection position moves to the upper part of working face. (2) With the increase of the stope height, the stress and displacement field of the surrounding rock using the backfilling method show an asymmetrical distribution, the movement, deformation, and failure increase slowly, and the increase of the strain is relatively stable. Compared with the caving method, the range and degree of the surrounding rock disturbed by the mining stress are lower. The results of numerical simulation and physical similarity simulation experiment are generally consistent with the theoretically derived results. Overall, this study can provide theoretical basis for the safe and efficient production of steeply dipping coal seams.

scholarly journals Stability Analysis and Derived Control Measures for Rock Surrounding a Roadway in a Lower Coal Seam under Concentrated Stress of a Coal Pillar

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhuoyue Sun ◽  
Yongzheng Wu ◽  
Zhiguo Lu ◽  
Youliang Feng ◽  
Xiaowei Chu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Numerical Simulations ◽  
Principal Stress ◽  
Coal Pillar ◽  
Control Measures ◽  
Stress Difference ◽  
Coal Seams ◽  
The Stability ◽  
Close Distance ◽  
Close Distance Coal Seams

Numerical simulations have often been used in close-distance coal seam studies. However, numerical simulations can contain certain subjective and objective limitations, such as high randomness and excessively simplified models. In this study, close-distance coal seams were mechanically modeled based on the half-plane theory. An analytical solution of the floor stress distribution was derived and visualized using Mathematica software. The principal stress difference was regarded as a stability criterion for the rock surrounding the roadway. Then, the evolution laws of the floor principal stress difference under different factors that influence stability were further examined. Finally, stability control measures for the rock surrounding the roadway in the lower coal seam were proposed. The results indicated the following: (1) The principal stress difference of the floor considers the centerline of the upper coal pillar as a symmetry axis and transmits radially downward. The principal stress difference in the rock surrounding the roadway gradually decreases as the distance from the upper coal pillar increases and can be ranked in the following order: left rib > roof > right rib. (2) The minimum principal stress difference zones are located at the center of the left and right “spirals,” which are obliquely below the edge of the upper coal pillar. This is an ideal position for the lower coal seam roadway. (3) The shallowness of the roadway, a small stress concentration coefficient, high level of coal cohesion, large coal internal friction angle, and appropriate lengthening of the working face of the upper coal seam are conducive to the stability of the lower coal seam roadway. (4) Through bolt (cable) support, borehole pressure relief, and pregrouting measures, the roof-to-floor and rib-to-rib convergence of the 13313 return airway is significantly reduced, and the stability of the rock surrounding the roadway is substantially improved. This research provides a theoretical basis and field experience for stabilizing the lower coal seam roadways in close-distance coal seams.

scholarly journals Stability Assessment of Deep Three-Soft Outburst Coal Seam Roof Based on Fuzzy Analytic Hierarchy Process

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qingling Meng ◽  
Yanling Wu ◽  
Minbo Zhang ◽  
Zichao Wang ◽  
Kejiang Lei
Keyword(s):  
Coal Seam ◽  
Analytic Hierarchy Process ◽  
Evaluation Method ◽  
Stability Assessment ◽  
Analytic Hierarchy ◽  
Soft Coal ◽  
Outburst Coal Seam ◽  
The Stability ◽  
Soft Coal Seam ◽  
Hierarchy Process

The stability of deep “three-soft” coal seam roof has always been a key issue in coal mining. There are a lot of factors affecting the stability of deep three-soft coal seam outburst roof. However, there is currently no definite method able to draw an accurate assessment conclusion on roof stability. In order to accurately determine the main influencing factors of the stability of deep three-soft coal seam outburst roof and reduce the loss of coal production, this paper performed three-soft coal seam risk identification on Lugou Mine based on the introduction of the fuzzy analytic hierarchy process theory. 23 main risk factors were identified. Then, it established a hierarchical structure model of coal seam roof stability in accordance with experts’ opinions. The analytic hierarchy process was used to calculate the weights of indicators at all levels. Next, the paper used the fuzzy comprehensive evaluation method and expert scoring to evaluate various risk factors in the indicator system, as well as the overall safety level. The results showed that the deep three-soft coal seam stability of Lugou Mine ranks the third hazard level. The main risk and harmful factors include safety awareness, safety monitoring system, roof weakness, ventilation system, fire-fighting system, and rock bolt quality. In response to the evaluation results, this paper formulated corresponding control measure in terms of ventilation risk, safety monitoring risks, construction personnel risks, and fire protection risk to reduce losses in the mining process, providing a new evaluation method for the stability assessment of deep outburst coal seam roof.

Fesibility Study on Mining Two-Confined-Water Coal Seam in North-China-Type Coalfield - Taking Shuangliu Coal Mine as the Example

2013 ◽  
Vol 807-809 ◽  
pp. 2378-2388 ◽  
Author(s):  
Hua Wang ◽  
Zhi Qiang Liu ◽  
Hong Guang Ji ◽  
Jin An Wang ◽  
Guo Dong Zhao ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Water Inrush ◽  
Damage Zone ◽  
Physical And Mechanical Properties ◽  
Shanxi Province ◽  
Confined Water ◽  
Coal Seams ◽  
Zone Water ◽  
Lower Group

Shuangliu mine is located in the middle of Hedong coalfield, Lvliang City , Shanxi Province. It is one of the typical NorthChinaType coalfields. The upper strata of the lower-group coal seams (8#, 9# seam) have several thin-layer limestones of the Taiyuan Formation, and the underlying strata of the lower-group coal seams have thick Ordovician limestone. Water inrush accident has ever happened in other mine in its vicinity. Therefore, whether the lower-group coal seams could be mined safely is related to the medium-and long-term program and sustainable development of Shuangliu Mine. Based on experimental study of physical and mechanical properties of main rocks of the roof and floor of the under-group coal seams, and the application of "Up Three Zone" Theory of coal seam roof (the caving zone, water flowing fractured zone and bending sinking zone), "Down Three Zone" Theory of coal seam floor (mining damage zone, water-resisting zone, water-conductive zone) and Water inrush coefficient Theory, we analyzed the water inrush risk and divided potential dangerous subareas of water inrush from coal seam floor while mining lower-group coal seams. The research findings can provide scientific basis for mining design and safe mining of lower-group coal seams in Shuangliu Coal Mine.

The Quantitative Evaluation of Coal Seam Stability Based on Component GIS

2012 ◽  
Vol 500 ◽  
pp. 168-174
Author(s):  
Long Quan Chen ◽  
Run Yuan Kuang
Keyword(s):  
Coal Seam ◽  
Quantitative Evaluation ◽  
Spatial Data ◽  
Theoretical Basis ◽  
Assessment System ◽  
Current Status ◽  
Stability Assessment ◽  
Stability Evaluation ◽  
Component Gis ◽  
The Stability

The stability of the mining is important for coal, and stability of the current status of coal was analyzed, selecting appropriate indicators that evaluate the importance of stability of the coal seam is so significant. Using GIS Spatial database to achieve a unified data management for spatial data and attributes, and analyze of coefficient of variation of coal thickness and correlation dimension of coal thickness, and use of these two indicators of a coal mine in the coal seam to analyze stability evaluation. Finally, developed stability assessment system of coal based on component-based GIS MapX. The results show that quantitative evaluation of the stability of the coal is reliable, can provide a theoretical basis for coal mining.

scholarly journals Stability of "Support-Surrounding Rock" System for Fully Mechanized Longwall Mining in Steeply Dipping Coal Seams

2021 ◽  
Author(s):  
Luo Shenghu ◽  
tong wang ◽  
Wu Yongping ◽  
Huangfu Jingyu ◽  
Zhao Huatao
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Stability Control ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Physical Test ◽  
Rock System ◽  
Working Face ◽  
The Stability ◽  
Mining Height

Abstract The key to the safe and efficient longwall mining of steeply dipping seams lies in the stability control of the "support-surrounding rock" system. This paper analyzes the difficulty of controlling the stability of the support during the longwall mining process of steeply dipping coal seams in terms of the characteristics of the non-uniform filled-in gob using a combination of physical test, theoretical analysis and field measurements. Considering the floor as an elastic foundation, we built a "support-surrounding rock" mechanical model based on data obtained on "support-surrounding rock" systems in different regions and the laws of support motion under different load conditions. Our findings are summarized as follows. First, depending on the angle of the coal seam, the caving gangue will roll (slide) downward along the incline, resulting in the formation of a non-uniform filling zone in the deep gob in which the lower, middle, and upper sections are filled, half-filled, and empty, respectively. In addition, an inverted triangular hollow surface is formed on the floor of the gob in the middle and upper sections behind the support. Furthermore, as the angle of the coal seam, length of the working face, and mining height increase, the characteristics of the non-uniform filled-in gob are enhanced. Second, we found that, as a result of support by the gangue, the "support-surrounding rock" system is relatively stable in the lower part of the working face while, in the middle and upper sections of the working face, the contact method and loading characteristics of the support are more complicated, making stability control difficult. Third, the magnitude and direction of the load, action point, and mining height all affect the stability of the support to varying degrees, with the tangential load and action position of the roof load having the most significant impacts on the stability of the support. Under loading by the roof, rotation and subsidence of the support inevitably occur, with gradually increasing amplitude and effects on the inter-support and sliding forces. Finally, we found that it is advisable in the process of moving the support to adopt "sliding advance of support" measures and to apply a "down-up" removal order to ensure overall stability. These research results provide reference and guidance of significance to field practice production.

Quantitative analysis of parameters' influence on the stability of coal roadway clamped by upper and lower soft rock with extra thickness

2014 ◽  
Vol 05 (02) ◽  
pp. 1350023
Author(s):  
Zenghui Zhao ◽  
Weiming Wang ◽  
Jixing Yan
Keyword(s):  
Quantitative Analysis ◽  
Coal Seam ◽  
Significant Influence ◽  
Evaluation Method ◽  
Soft Rock ◽  
Mining Area ◽  
Remarkable Effect ◽  
Coal Roadway ◽  
The Stability ◽  
Rock Strata

In this paper, a physical model of coal roadway which is clamped by upper and lower soft rock with extra thickness was built according to the characteristics of soft rock strata in china's western mining area. Then, a series of orthogonal numerical experiments were carried out by selecting the strength and stiffness parameters of soft rock and coal seam as well as the in situ stress of soft rock strata as experimental factors and roadway displacements (convergence displacements of sides, displacement of roof to floor) as experimental indexes. By constructing the F statistics with different inspection levels, evaluation method for influence of the experimental factors on stability indexes were defined. Thus, influence degrees of specified parameters on the stability of roadway were divided into five classes as follows: highly significant influence, significant influence, relatively significant influence, little significant influence, and no influence respectively which realize the quantitative analysis of the influence degrees of experimental factors. The finite element calculation results showed that main failure mode of coal roadway that usually showed as tension failure of coal seam in roof and deformation factors of coal seam had the most remarkable effect on roadway displacements. The conclusions provide theoretical basis for further analysis of the mechanism of "roof burst" in roadway maintenance.

scholarly journals Research on safety evaluation of bolt support based on analytic hierarchy process-entropy weight method

2020 ◽  
Vol 213 ◽  
pp. 03019
Author(s):  
Junqing Wang ◽  
Qinggui Cao ◽  
Xin Mi ◽  
Dan Li
Keyword(s):  
Evaluation System ◽  
Evaluation Method ◽  
Safety Evaluation ◽  
Evaluation Index System ◽  
Shanxi Province ◽  
Entropy Weight ◽  
Application Program ◽  
Entropy Weight Method ◽  
Weight Method ◽  
Bolt Support

To evaluate the safety performance of bolt support scientifically, the factors affecting bolt support are systematically analyzed, the comprehensive evaluation index system is established from four aspects: support parameters, quality of bolt and fittings, construction management and monitoring level, and the safety evaluation model of bolt support is constructed; the AHP and entropy weight method are combined to determine the weight of each index, and the safety evaluation system of bolt support based on AHPentropy weight method is established and its application program is developed. The safety evaluation method and application program proposed in this paper are applied to the safety evaluation of bolt support in a coal mine in Shanxi Province, and the results are in agreement with the actual situation. This article studies the correlation.

scholarly journals A Method for Quantitative Evaluation of Seismic Stability of Loess Slope Based on the Shaking Table Model Test

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Pu Xiaowu ◽  
Wang Lanmin ◽  
Wang Ping ◽  
Chai Shaofeng ◽  
Xu Shiyang
Keyword(s):  
Model Test ◽  
Evaluation Method ◽  
Shaking Table ◽  
Seismic Stability ◽  
Stability Evaluation ◽  
Loess Slope ◽  
Critical Instability ◽  
Table Model ◽  
The Stability ◽  
Shaking Table Model Test

The large-scale shaking table model test, which can directly reproduce the process of slope instability and failure, is an important technical means for the prediction and evaluation of slope seismic stability. However, up to now, the systematic slope stability evaluation method based on the shaking table slope model test has not been established, which limits the application of the expensive shaking table model test in slope seismic design. Therefore, the slope stability evaluation method based on the model test needs to be developed and innovated. In this research, through three loess slope model tests with different rainfall, according to the change law of the peak value of transfer function spectrum, combined with the macrodestructive characteristics of the slope model, an accurate calculation method of the critical instability acceleration of the slope is proposed. Based on the behavior similarity theory, for the shaking table model test of slope whose soil cohesion cannot meet the similarity ratio, the reduction method of applying the critical instability acceleration obtained from the model test to prototype slope is proposed. Based on first-order natural frequency and damping ratio extracted from the TF spectrum curve, a calculation method for the stability factor Fs of loess slope based on the shaking table model test is proposed, and the stability factors of loess slope under the action of different seismic ground motion would be quantitatively calculated. The above methods provide another effective way for qualitative prediction and evaluation of seismic stability of loess slope.

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