Field Study on the Law of Surface Subsidence in the High-Intensity Fully Mechanized Caving Mining Working Face with Shallow Thick Bedrock and Thin Epipedon in Hilly Areas

Shallow and thick coal seams occur extensively in hilly areas in Shanxi Province and Shaanxi Province, China. The surface damage and landslides caused by shallow fully mechanized caving mining have a very serious impact on the environment. To provide a theoretical and reference foundation for mine environmental protection in hilly settings, a research on surface movement of the high-intensity fully mechanized caving mining working face with shallow thick bedrock and thin epipedon (HIFMCMWFSTBTE) is urgently needed. In this study, using the P2 working face of a mine as the research object, three surface subsidence observation lines were arranged in this working face to analyze the dynamic change characteristics of surface subsidence. Besides, the law of surface movement, mining sufficiency, fracture development and distribution characteristics, subsidence speed, and surface movement duration of HIFMCMWFSTBTE in hilly areas were comparatively studied. The research results reveal that the upper part of the slope slides towards the downhill direction under the action of tensile stress or push stress. As a result, the range of the horizontal movement towards the downhill direction of the slope and the range of surface movement both increase, and the movement angle and boundary angle both decrease compared with the plain. HIFMCMWFSTBTE is prone to serious sudden discontinuous damage. Fractures on the gully region surface develop along the contour, forming a crisscross fracture network, and the fractures are not easy to close after being generated. HIFMCMWFSTBTE in hilly areas can achieve full mining more easily than those of other geological conditions. According to the field measurement, critical full mining can be achieved in P2 working face when the ratio of mining width to mining depth is 1.07. The surface movement duration of HIFMCMWFSTBTE in hilly areas is relatively short. Considerable subsidence will occur in the active stage, and the surface subsidence is sudden and violent. The measured surface stabilization time of the P2 working face is only 20% of the calculated value in the Specification for Coal Pillar Reservation and Coal Mining under Buildings, Water Bodies, Railways, and Main Shafts (hereinafter referred to as the Specification), indicating that the specification's empirical formula is inapplicable to the calculation of surface stabilization time of the P2 working face.

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Study on the Law of Earth’s Surface Movement on Ultra-Long Working Face

Geotechnical and Geological Engineering ◽

10.1007/s10706-021-01886-w ◽

2021 ◽

Author(s):

Peng Rui ◽

Fang Meiling ◽

Ren Ruile ◽

Zhu Jianming ◽

Zhao Qifeng ◽

...

Keyword(s):

Surface Movement ◽

Working Face ◽

The Law

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Analysis on Characteristics of Surface Subsidence with Han Jia Wan Coal Mine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.524-527.520 ◽

2012 ◽

Vol 524-527 ◽

pp. 520-524 ◽

Cited By ~ 1

Author(s):

Xue Yi Yu ◽

Peng Wang ◽

Xing Liang Li

Keyword(s):

Coal Mine ◽

Scientific Basis ◽

Surface Subsidence ◽

Surface Cracks ◽

Surface Movement ◽

Working Face ◽

Shallow Coal Seam ◽

Movement And Deformation ◽

Main Factors ◽

Movement Parameters

Surface subsidence has some peculiarities for the mining of the Han jia wan coal mine. Based on the surface movement observation of 2304 working face in Han jia wan coal mine, mining strata movement parameters are analyzed, the main factors which influence the formation of surface cracks in the gob are proposed and the failure mechanism of surface movement and deformation are studied for the mining of shallow coal seam and thick loose bed. Correlative parameters are presented and scientific basis is established for the coal mining under buildings, rail and water and the leaving of the safety pillar in the future.

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Study on the Law of Earth’s Surface Movement on Ultra-long Working Face

10.21203/rs.3.rs-424481/v1 ◽

2021 ◽

Author(s):

Rui Peng ◽

Fang Meiling ◽

Ren Ruile ◽

Zhu Jianming ◽

Qifeng Zhao ◽

...

Keyword(s):

Coal Mining ◽

Simulation Software ◽

Coal Bed ◽

Length Effect ◽

Surface Movement ◽

Working Face ◽

Face Length ◽

The Face ◽

The Law ◽

Rock Strata

Abstract The problem of stoping on ultra-long working face is one of challenges for making coal mining safe and efficient. The strong mining effect of surrounding rock induced by long working face mining causes a number of coal or rock dynamic disasters to safe and efficient coal mining. For the purpose of in-depth study of the law of earth’s surface movement on ultra-long working face, this paper, with FLAC3D (numerical simulation software) used to build a numerical model of ultra-long working face, analyzes the law of roof-to-floor strata behaviors in coal bed during mining, and studies the weakening of roof-to-floor parameters in coal bed, bearing pressure and the law of roof caving and rock strata movement; Analyzes the face length effect resulted from the difference in face lengths. It has been recognized that the sphere of influence of bearing pressure changes from small to large and then to small, and changes in distribution of arch bottom and arch height at the plastic failure zone are further intensified over advancing of the working face, moreover, the movement of rock strata is subject to the cumulative influence of the advancing direction of the working face and the face length effect. The above-mentioned research results can serve as a theoretical basis for practical engineering.

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Determining The Minimum Distance Between Centers of Two Parallel Tunnels to Apply The Law of Super Position in Order to Calculate Subsidence by Using The Software FLAC 3D

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v1i1.2139 ◽

2015 ◽

Vol 1 (1) ◽

pp. 13-20

Author(s):

Hamid Reza Samadi ◽

Mohammad Reza Samadi

Keyword(s):

Minimum Distance ◽

Surface Subsidence ◽

Urban Traffic ◽

Underground Structures ◽

Rapid Population Growth ◽

The North ◽

Flac 3D ◽

The Law ◽

3D Software ◽

Twin Tunnels

Due to the development of cities as well as rapid population growth, urban traffic is increasing nowadays. Hence, to improve traffic flow, underground structures such as metro, especially in metropolises, are inevitable. This paper is a research on the twin tunnels Of Isfahan's metro between Shariaty station and Azadi station from the North towards the South. In this study, simultaneous drilling of subway's twin tunnels is simulated by means of Finite Difference Method (FDM) and FLAC 3D software. Moreover, the lowest distance between two tunnels is determined in a way that the Law of Super Position could be utilized to manually calculate the amount of surface subsidence, resulted by drilling two tunnels, by employing the results of the analysis of single tunnels without using simultaneous examination and simulation. In this paper, this distance is called "effective distance". For this purpose, first, the optimum dimensions of the model is chosen and then, five models with optimum dimensions will be analyzed separately, each of which in three steps. The results of analyses shows that the proportions (L/D) greater than or equal 2.80, the Law of Super Position can be applied for prediction of surface subsidence, caused by twin tunnels' construction

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Control Technology of Surface Movement Scope with Directional Hydraulic Fracturing Technology in Longwall Mining: A Case Study

Energies ◽

10.3390/en12183480 ◽

2019 ◽

Vol 12 (18) ◽

pp. 3480 ◽

Cited By ~ 2

Author(s):

Zhanjie Feng ◽

Wenbing Guo ◽

Feiya Xu ◽

Daming Yang ◽

Weiqiang Yang

Keyword(s):

Numerical Simulation ◽

Hydraulic Fracturing ◽

Longwall Mining ◽

Numerical Models ◽

Surface Subsidence ◽

The Sustainable Development ◽

Surface Movement ◽

Directional Hydraulic Fracturing ◽

Simulation Results ◽

Overlying Strata

Mining-induced surface subsidence causes a series of environmental hazards and social problems, including farmland destruction, waterlogging and building damage in the subsidence area. To reduce mining damages, an innovative method of controlling the surface movement scope via artificial weak planes generated by hydraulic fracturing technology was proposed in this paper. Numerical models were built to analyze the influence of weak planes with different heights and dips on the overlying strata movement. The numerical simulation results showed that the weak planes structure cut off the development of the overlying strata displacement to the surface and affected the surface movement scope. When the weak planes’ dips were bigger than the angle of critical deformation, with the increase of the weak planes’ heights (0–120 m) the advance angle of influence changed from 53.61° to 59.15°, and the advance distance of influence changed from 173.31 m to 140.27 m which decreased by 30.04 m. In applications at Sihe coal mine in China, directional hydraulic fracturing technology was used in panel 5304 to form artificial weak planes in overlying strata. The measured surface subsidence and deformation value met the numerical simulation results and the mining-induced surface movement scope reduced. Moreover, no damage occurred to the surface buildings which were predicted to be in the affected area after extraction. This technology provided a new method to protect the surface structures from damages and had great benefits for the sustainable development of coal mines.

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Going Beyond the Western Pass: Chinese Folk Models of Danger and Abandonment in Songs of Separation

Modern China ◽

10.1177/0097700419874888 ◽

2019 ◽

Vol 46 (5) ◽

pp. 490-520

Author(s):

Levi S. Gibbs

Keyword(s):

Northern China ◽

Shaanxi Province ◽

Shanxi Province ◽

Public Language ◽

Left Behind ◽

Ethnographic Interviews ◽

Migrant Laborers ◽

Song Lyrics ◽

Folk Models ◽

Great Wall

From the early Qing dynasty (1644–1911) to the beginning of the People’s Republic, men in northern China from drought-prone regions of northwestern Shanxi province and northeastern Shaanxi province would travel beyond the Great Wall to find work in western Inner Mongolia, in a migration known as “going beyond the Western Pass” 走西口. This article analyzes anthologized song lyrics and ethnographic interviews about this migration to explore how songs of separation performed at temple fairs approached danger and abandonment using traditional metaphors and “folk models” similar to those of parents protecting children from life’s hazards and widows and widowers lamenting the loss of loved ones. I argue that these duets between singers embodying the roles of migrant laborers and the women they left behind provided a public language for audiences to reflect upon and contextualize private emotions in a broader social context, offering rhetorical resolutions to ambivalent anxieties.

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Movement Law and Discriminant Method of Key Strata Breakage Based on Microseismic Monitoring

Shock and Vibration ◽

10.1155/2019/8652894 ◽

2019 ◽

Vol 2019 ◽

pp. 1-19 ◽

Cited By ~ 1

Author(s):

Yang Li ◽

Tianhong Yang ◽

Weidong Song ◽

Ling Yu

Keyword(s):

High Intensity ◽

Microseismic Monitoring ◽

Geological Structure ◽

Western China ◽

Dynamic Monitoring ◽

Ecological Environment ◽

Environmental Damage ◽

Key Strata ◽

Key Stratum ◽

Working Face

Because of the unique natural geography, geological structure, and ecological environment, there are serious geological disasters and environmental damage caused by the high-intensity mining in Western China. It seriously restricts the development of coal resources and the protection of ecological environment. In order to fully capture the law of key stratum breakage with high-intensity mining, the IMS microseismic system was introduced into Xiaojihan coal mine which is a typical high-intensity mining mine in Western China, and the whole process dynamic monitoring was carried out. The process of key stratum breakage was analysed by MS data, which were in agreement with the pressure analysis results of the hydraulic support of the working face. The results showed that there were the obvious forewarning characteristics in microseismic event number, energy release, energy index, Schmidt number, coefficient of seismic response, and b value when the key stratum was breaking. Then, a method to discriminate the breakage of key stratum was proposed by using the forewarning characteristics, which could provide the guidance for prevention and control of geological hazards in the working face with high-intensity mining.

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Study On The Law Of Ground Strata Subsidence And Movement Induced By Caving Mining Of Slowly Inclined Large And Thick Ore Body

E3S Web of Conferences ◽

10.1051/e3sconf/20185303062 ◽

2018 ◽

Vol 53 ◽

pp. 03062

Author(s):

Li Teng ◽

Fu Jianxin ◽

Song Weidong

Keyword(s):

Underground Mining ◽

Ground Surface ◽

Beam Theory ◽

Tectonic Stress ◽

Collapse Mechanism ◽

Surface Movement ◽

Strata Movement ◽

Leading Role ◽

Metal Mine ◽

The Law

Taking the Western District of Chengchao Iron Mine as engineering background, based on the GPS monitoring data of nearly 8 years and the record of the ground surface movement, the law of ground strata subsidence and movement is studied. The studies have shown that the surface movement caused by underground mining has the characteristics of time delay and displacement angle development has the law of jumping. The strata movement caused by mining is divided into the stage of overlying strata collapse and the collapse stage of surrounding rock to goaf. In the first stage, the vertical stress plays a leading role and rock failure is shown as a regular barrel collapse. In the second stage, horizontal tectonic stress plays a leading role and the collapse mechanism of rock strata can be explained by the cantilever beam theory. According to the mechanism of strata movement analysis, strata movement of Chengchao Iron is divided into six regions, which respectively included vertical subsidence area, toppling sliding zone, dumping area, deformation zone, cumulative deformation area and undisturbed zone. The results of this paper can provide a theoretical basis for the surface movement prediction of caving mining in similar metal mine.

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The Stability of Gob-Side Entry Retaining in a High-Gas-Risk Mine

Advances in Civil Engineering ◽

10.1155/2019/7540749 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Junwen Zhang ◽

Yulin Li

Keyword(s):

Coal Mines ◽

Surrounding Rock ◽

Shanxi Province ◽

Engineering Practice ◽

Efficient Production ◽

Coal Recovery ◽

Working Face ◽

Geological Conditions ◽

The Stability ◽

Strengthening Technique

There are series of problems faced by most of the coal mines in China, ranging from low-coal recovery rate and strained replacement of working faces to gas accumulation in the upper corner of coalfaces. Based on the gob-side entry retaining at the No. 18205 working face in a coal mine in Shanxi Province, theoretical analysis, numerical simulation, and engineering practice were comprehensively used to study the mechanical characteristics of the influence of the width of the filling body beside the roadway and the stability of surrounding rock in a high-gas-risk mine. The rational width of the filling body beside the roadway was determined, and a concrete roadway-side support with a headed reinforcement-integrated strengthening technique was proposed, which have been applied in engineering practice. The stability of the filling body beside the roadway is mainly influenced by the movement of the overlying rock strata, and the stability of the surrounding rock can be improved effectively by rationally determining the width of the filling body beside the roadway. When the width of the roadway-side filling body is 2.5 m, the surrounding rock convergence of the gob-side entry retaining is relatively small at only 5% of the convergence ratio. It has been shown that the figure for roof separation is relatively low, and strata behaviors are relatively alleviated and gas density do not exceed the limit, which are the best results of gob-side entry retaining. The results of this research can provide theoretical guidance for excavation of coal mines with similar geological conditions and have some referential significance to safety and efficient production in coal mines.

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Numerical Simulation of Mining Overburden and Surface Deformation Law

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.962-965.1066 ◽

2014 ◽

Vol 962-965 ◽

pp. 1066-1069

Author(s):

De Shen Zhao ◽

Dong Liang Guo

Keyword(s):

Numerical Simulation ◽

Surface Deformation ◽

Zero Point ◽

Deformation Curve ◽

Two Dimensional ◽

Horizontal Deformation ◽

Horizontal Movement ◽

Surface Movement ◽

Working Face ◽

Deformation Law

In order to obtain overburden and surface deformation law, this paper takes S2S9 working face fully-mechanized mining of certain coal mine for example, uses the finite element ADINA software, and it establishes two-dimensional numerical model, analyzes overburden and surface deformation caused by the working face mining. The study shows the amount of each point movement in the top of the mined-out area gradually decreases from the bottom to up, and the range of surface movement is also increasing with advancement of the coal excavation. After the completion of the working face, it forms a subsidence curve which is symmetry for the maximum vertical point and an antisymmetric horizontal deformation curve. The zero point of horizontal movement is located above the center of mining sector, and the maximum tilt is 2.044mm·m.

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