CC BY
9ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
Original article / Оригинальная статья УДК 574:631.4:631.504
DOI: http://dx.doi.org/10.21285/2500-1582-2018-2-44-51
STUDY ON SAFETY OF COMBINED MINING OF EXTREMELY-NEAR LOCATED COAL BEDS IN DAANSHAN COAL MINE
© Wang Junguang1, Wang Pengjin2, Liang Bing3, Li Cunzhou4
'' Liaoning University of Engineering and Technology Institution of Mechanics and Engineering, Xihe District, Fuxin city, Liaoning Province, People's Republic of China, 123000 4Liaoning University of Engineering and Technology Institute of mining technology, Xihe District, Fuxin city, Liaoning Province, People's Republic of China, 123000
ABSTRACT. The upper and lower coal beds located at +400 m level of Daanshan Coal Mine were selected to study extremely near located coal beds which are mined using a combined method under a composite roof. The results show that under the stratified mining the aim can be achieved when the upper layer is mined after "extrusion - extrusion unloading support and moving frame in a double unloading process". A large number of cracks will be generated in the gangue, and the degree of fragmentation will increase. Moreover, the smaller the malposition between the upper and lower working faces is, the more serious the damage is. The reasonable malposition of the upper and lower seams of the shaft 10 at +400 m level is 20 m. Selecting the DW14-300 / 100X type single prop to support the composite roof will improve the support effect which can ensure safe production of the working surface. The research results provide experimental and theoretical basis for the stability of the working surfaces in mining at a close distance from the coal seam. Keywords: compound roof, close distance, malposition, strata pressure
Information about the article. Received in March 11, 2018; accepted for publication in April 20, 2018; available online on June 21, 2018.
For citation. Wang Junguang, Wang Pengjin, Liang Bing, Li Cunzhou. Study on safety of combined mining of extremely-near located coal beds in Daanshan coal mine. XXI vek. Tekhnosfernaya bezopasnost' = XXI century. Technosphere Safety. 2018, vol. 3, no. 2 (10), pp. 44-51. DOI: 10.21285/2500-1582-2018-2-44-51
ИССЛЕДОВАНИЕ ПО БЕЗОПАСНОЙ КОМБИНИРОВАННОЙ ДОБЫЧЕ
ЭКСТРЕМАЛЬНО БЛИЗКО РАСПОЛОЖЕННЫХ ПЛАСТОВ НА УГОЛЬНОЙ ШАХТЕ «ДААНШАНЬ» Ван Жунгуань, Ван Пенджин, Лянь Бинь, Ли Сунджу
Ляонинский университет машиностроительного и технологического института механики и машиностроения, Фусинь, провинция Ляонин, Китайская Народная Республика, 123000 Ляонинский институт горной техники,
Фусинь, провинция Ляонин, Китайская Народная Республика, 123000
РЕЗЮМЕ. Стремясь к безопасному использованию крайне близкого угольного пласта при комбинированной добыче в условиях составной кровли угольной шахты Дааншань, для исследования были выбраны верхний и нижний угольные пласты шахтных щелей 10, расположенных на уровне +400 м. Результаты показывают: эффект
1
Wang Junguang, Doctor, Senior Lecturer, e-mail: shenliu_303@163.com
Ван Жунгуань, доктор технических наук, старший преподаватель, e-mail: shenliu_303@163.com
2Wang Pengjin, Doctor, Senior Lecturer, e-mail: shenliu_303@163.com
Ван Пенджин, доктор технических наук, старший преподаватель, e-mail: shenliu_303@163.com
3Liang Bing, Lecturer, e-mail: shenliu_303@163.com
Лянь Бинь, преподаватель, e-mail: shenliu_303@163.com
4Li Cunzhou, Doctor, Senior Lecturer, e-mail: shenliu_303@163.com
Ли Сунджу, доктор технических наук, старший преподаватель, e-mail: shenliu_303@163.com
Том 3, № 2 2018 XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ Vol. 3, no. 2 2018 XXI CENTURY. TECHNOSPHERE SAFETY
ISNN 2500-1582
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
достигается при условии стратифицированной добычи, когда верхний слой разрабатывается после прохождения процесса экструзии - экструзионно-разгрузочной поддержки экструзии и движущейся рамы при двойной разгрузке. Большое количество трещин будет генерироваться в жилах, а степень фрагментации возрастет. Более того, чем меньше неправильное расположение верхней и нижней рабочих поверхностей, тем серьезнее ущерб. Разумное расположение верхнего и нижнего шва вала 10 на уровне +400 м составляет 20 м. Выбор одиночной опоры DW14-300 / 100Х для поддержки композитной кровли сделает эффект поддержки хорошим, что может обеспечить безопасное производство рабочей поверхности. Результаты исследований обеспечивают экспериментальную и теоретическую основу для устойчивости рабочих поверхностей при комбинированной добыче на крайне близком расстоянии от угольного пласта.
Ключевые слова: сложная кровля, близкое расстояние, неправильное расположение, давление пластов.
Информация о статье. Дата поступления 11 марта 2018 г.; дата принятия к печати 20 апреля 2018 г.; дата он-лайн-размещения 21 июня 2018 г.
Формат цитирования: Ван Жунгуань, Ван Пенджин, Лянь Бинь, Ли Сунджу. Исследование по безопасной комбинированной добыче экстремально близко расположенных пластов на угольной шахте «Дааншань» // XXI век. Техносферная безопасность. 2018. Т. 3. № 2 (10). С. 44-51. РО!: 10.21285/2500-1582-2018-2-44-51
Introduction
The upper and lower two coal seam faces influence each other when close distance seams mines simultaneously. In the process of upper coal seam mining, the mining stress is transferred to the deep through the inter layer rock, which affects the stress distribution of the lower coal seam [1, 2]. Under the condition that close distance seams mines simultaneously, if the malposition between the upper and lower two coal seams is too large, it will lead to difficulty in production connection and difficult to guarantee the production in the late stage of the coal mine. When the malposition is too small, the interaction between the upper and lower coal seams is serious, and the surrounding rock of the working face is difficult to control, especially under the weak broken roof [2, 3]. Therefore, it is of great theoretical and practical significance to study the issue of reasonable malposition and the rule of underground pressure under the conditions of combined mining with short distance coal seam. Experts and scholars at home and abroad carried out in-depth research on combined mining of close distance coal seams, and achieved a lot of results. Kang Jian and so on take the Zhengyang coal mine of Jixi mining branch of long coal group as the research object, analyzing the overlying strata movement law of the extremely close thin coal seam mines simultaneously, obtaining the
reasonable malposition of the simultaneous mining face. Sun Chundong et al. studied the pressure law of combined mining in 1m extremely close seams. Zha Wenhua carried the research aiming at the combined mining of extremely close distance coal seam under the condition of hard roof. Yan Guochao et al. analyzed the law of coal seam pressure and the reasonable malposition of combined mining of very close seams by a combination of theoretical analysis and physical simulation
methods [4 - 7]. The distance between upper and lower seams located in Daanshan Mine +400 horizontal axis 10 slots is close. The geological condition of the coal seam is complex, the roof joints and fissures are developed, and the mining face has great potential safety hazard. This paper mainly studies the reasonable malposition and mine pressure law of the close distance coal seam when combined mining under the condition of upper and lower coal seam compound roof 400 horizontal shafts and 10 troughs of Da'an coal mine in Beijing. By means of theoretical analysis, numerical simulation and field measurement, the reasonable malposition of simultaneous mining of coal seams is comprehensively determined so as to realize the safe and efficient mining of very close distance coal seams when combined mining.
Том 3, № 2 2018 Vol. 3, no. 2 2018
XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ XXI CENTURY. TECHNOSPHERE SAFETY
ISNN 2500-1582
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
Project profile
The seam of +400 levels axis 10 slots of Da Anshan coal mine which belongs to Beijing Haohua Energy Co., Ltd develops extremely unstably. It is obviously influenced by structure. The area is located in the axis of the tectonic site. The rock strata generally go from 70-110°, with a tendency of 20-340°, dip 1128° and average dip 19°. Affected by the structure, the occurrence of coal rock and the thickness of coal seam vary greatly near two axes of Baicao inverted reversing. Regional coal seam roof joints, cracks are more developed. The fault whose fault throw is below 2 m develops wavily. It is a typical soft broken roof. The average thickness of the shaft 10 seam coal seam is 2.40 m. The most part of the coal seam contains a stone with average thickness of 1.0 m. The average thickness of coal seam under the stone is 1.10 m. During the process of axis 10 slot coal seam mining, because the
coal seam is sandwiched with nearly 1.0 m clip stone and the geological structure is complex and the roof of coal seam is soft and broken. It makes the mine pressure appears obviously during the mining process, which makes it difficult to support the roadway. Comprehensively considering the mine production conditions and on-site geological conditions, we can take malposition combined mining scheme to mine extremely close distance coal seam. For this reason, under the condition of soft roof, the determination of the malposition when combined mining and the characteristics of strata pressure are the main problems to solve. It can not only ensure safe mining, but also maximize the recovery of coal resources and improve the economic benefits of coal mines which is of great significance to the long-term development strategy of the mine.
Simultaneous Numerical of Extremely Close Distance Coal Seam When Mining Simultaneously in Daanshan Coal Mine
Numerical simulation model. Because the similar material consumes a lot of time and it is difficult to realize the law of occurrence of underground pressure under a variety of malposition, the numerical method is
adopted [8, 10 -12]. Numerical simulations mainly simulate the features of ground pressure and malposition when very close up and down working face in Shaft 10 slots mines simultaneously. The model establishes a plane model along the strike, and the length is 200 m x 110 m. Daanshan coal mine shaft 10 seam is buried in depth of 500 m. According to the actual situation of 500 m overburden thickness, the vertical stress 12.5 MPa is applied to the horizontal boundary of the upper model. The horizontal constraint is applied to the left and right vertical boundaries of the
model, and the vertical constraint is applied at the bottom boundary of the model. The whole constraint considers the distribution of stress, deformation and failure under the condition of weight. The Mohr Kulun model is chosen for the constitutive model. The mechanical parameters of coal seam and rock are based on the experimental results, as shown in Table. The numerical calculation is mainly aimed at the analysis of the malposition when combined slice-mining for upper and lower face of 10 slots of this mine. The stress, displacement and damage of overlying strata and the deformation of the roof after the hydraulic support moves are simulated respectively under the condition that malposition of upper and lower working face is 10 m, 20 m, 30 m.
f4f
vOy
Том 3, № 2 2018 Vol. 3, no. 2 2018
XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ XXI CENTURY. TECHNOSPHERE SAFETY
4 А/
ISNN 2500-1582 V
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
Mechanical parameters of coal seam and rock based on experimental results
Rock Name Specimen size Compressio n strength, MPa Tensile strength,M Pa Bulk weight, t/m3 Elastic Modulus,MP a Poisson' s ratio Cohesion C, MPa Internal friction angle, °
length Width
main roof of shaft 10up 5.11 5.09 149 8.2132 3.1387 6438.6864 0.4221 17.7687 41.2343
direct top of shaft 10up 4.98 5.08 94 7.9645 3.0701 5986.0432 0.3981 14.6156 40.1432
coal seam of shaft 10up 4.95 5.13 22 1,2821 1.8322 1478.3423 0.1632 2.9878 33.9856
stone folder of shaft 10 5.21 5.06 60 6.5467 2.6821 5757.7675 0.2785 7.5883 42.0967
coal seam of shaft 10dowm 5.21 5.13 27 1.3446 1.7829 1321.8097 0.1709 3.1377 33.0768
direct floor of shaft 10dowm 5.00 4.96 125 6.4533 2.6432 6214.3091 0.2733 16.3298 33.8021
old floor of shaft 10dowm 5.03 4.89 147 6.9876 2.7945 6534.9877 0.4467 18.3278 44.0979
Simulation results and analysis.
When the malposition of upper and lower coal seam range from 0 to 10 m, with the upper and lower working face advances, the coal wall, floor (folder gangue) of upper coal seam destroyed seriously, and have a serious floor heave. For the lower working face, the roof crushed. The roof falling of the upper layer will cause serious impact damage to the lower working face. There will exist roof fall in front of the hydraulic support under the work surface. The vertical stress in the coal seam and gangue in front of the upper working face is compressive stress, which is more concentrated, and part of it reaches 33 MPa. It will lead to further crushing of the gangue. The upward displacement of the gangue near the coal wall in the upper working face is large which shows that the gangue rises up to the working face; the downward displacement of the gangue near the coal wall in the lower working face shows that there is a large amount of roof fall in the roof (fig. 1).
When the malposition between the upper and lower coal seams is 15-20 m (fig. 2), the vertical stress in front of the coal face and gangue in the working face is compressive stress. The stress concentration factor is obviously reduced, and the damage degree of the
gangue is also reduced. The maximum of vertical stress decreases to 29 MPa in the surrounding rock of the lower working face. The upward displacement of the gangue near the coal wall in the upper working face is obviously reduced, which indicates that the amount of the upper working face of the gangue is obviously reduced. When the malposition reaches 20 m, the roof fall phenomenon disappears basically. When the malposition reaches 30 m, the roof falling phenomenon continues to appear, which shows that the stagger distance 20m is the best malposition.
Under the condition of slicing mining (fig. 3, 4), when the upper layer is mined, after experiencing the process of "extrusion-unloading-stent support squeezing-moving frame secondary unloading". A large number of cracks will be generated in the gangue, and the degree of fragmentation will increase. Moreover, the damage degree of the upper and lower working face decreases first and then increases with the increase of malposition. Under the condition of slicing mining, when the upper layer has been mined and the lower coal seam is mining, the roof collapse is easy to occur because of the roof broken, which brings difficulties to support.
Том 3, № 2 2018 Vol. 3, no. 2 2018
XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ XXI CENTURY. TECHNOSPHERE SAFETY
ISNN 2500-1582
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
(a) malposition is 10 m (b) malposition is 20 m (c) malposition is 30 m
Fig. 1. Distribution diagram of rock failure area
(a) malposition is 10 m (b) malposition is 20 m (c) malposition is 30 m
Fig. 2. Rock displacement vector diagram
ШЖС (Vmrwtoa 4ЛО) ■ fc M M ■ i 11
Май |M âfsfrj вщцл мт Mta 1 1 Г L ibth-f 1 Ici- 1
1 г г г 11 1II
л ■ л ■ .ji ■ л ■ -
(a) Gangue roof condition before advancing support
(b) Caving condition of gangue roof when advancing support
Fig. 3. Roof failure of clip gangway roof before and after face support advances
for axis 10 working face
т. ti iwni
(a) malposition is 10 m
(b) malposition is 20 m Fig. 4. Vertical stress monitoring curve
(c) malposition is 30 m
kÖM
Том 3, № 2 2018 XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ Vol. 3, no. 2 2018 XXI CENTURY. TECHNOSPHERE SAFETY
ч А/
ISNN 2500-1582 V
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
Field measurement and analysis
The west side of the 400 horizontal shaft 10 channel seam of Daanshan the coal mine is selected as the field test section. Adopting 20 m as field test malposition to observe the pillar pressure of Working face and upper and lower groove during mining. According to the numerical results and combing the related theory, the DW14-300/100X type single prop was selected for support scheme. The basic parameters of the pillar are as follows: maximum height 1.4 m, minimum height 0.81 m. Working stroke 0.59 m, rated working resistance 300 KN, rated working pressure 41.5 MPa, initial support force 114 Kn, base area 113 cm2. 3-4 rows of pillar was selected to control top. And row spacing is 0.8 m, column spacing is 0.9 m. Add a cut-top intensive column was set between the two pillars of the end row.
Rock pressure observation equipment and measuring point arrangement. Observation equipment. The lower coal seam roof of the shaft 10 is a compound roof, and the thickness of the coal seam is unstable, which brings some difficulties to the supporting quality of the working face and the safety of the working face. Therefore, the working face of lower coal seam of shaft 10 is observed on the spot. Due to the large geological conditions of coal seams and the inaccuracy of the monitoring data, the mine pressure curve of the working face is slightly different from the actual situation. The distance change between roof, floor and two
sides of roadway was measured with 5 m steel tape. The YHY-60 digital pressure gauge is used to measure the working resistance of single hydraulic prop. The QLDC-1 roof abscission layer distance measuring instrument is adopted to measure the roof abscission layer. The MCZ-300 type bolt (cable) dynamometer was used to determine anchor (cable) anchoring force.
Observation methods and measuring point arrangement. After setting up the instrument on the observation base point located in the top of the roadway, the floor and the two sides of roadway, we must write down the initial value, liste, number. Dentification management was required for each station. Each station is required to observe once every two days. Every 4.8 meters from the recovery lane to the goaf direction, the pressure measuring point of the single hydraulic prop is arranged. A total of 13 sets of measuring points are arranged, and 13 single hydraulic prop pressure detectors are installed. The layout effect of the measuring point of the single hydraulic prop pressure detector is shown in Figure 5 pressure measuring points are installed on the upper groove and the lower trough respectively for the measurement of supporting load on upper and lower channels, and the distance between the measuring points is 5 m. Observation results and analysis. We know from the observation curve (fig. 6, 7).
Ш/
Fig. 5. Pressure detector layout diagram of single hydraulic prop
Том 3, № 2 2018 XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ Vol. 3, no. 2 2018 XXI CENTURY. TECHNOSPHERE SAFETY
ISNN 2500-1582
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
4O 35 3O S 25 ~ 2O 2 15 1O 5 O
y y y y Н1Ю
-ШЯ1
ЯЯ2 ЯЯ3 ЯЯ4 ЯЯ5 ЯЯ6 ЯЯ7 ЯЯ8 ЯЯ9 ^Я10
ЯЯ11
ЯЯ12 ЖЯ13
Fig. б. Measurement curve for single pillar pressure
TISfttiäB
35 3O 25
S 2O f- 15
m
Fig. 7. Monitoring data curve for upper and down groove
From the observation data and curves, the roof pressure of most of the measuring points is larger and the biggest is the 11 measuring point of the working face. The maximum pressure is 35 MPa. And the pressure of the measuring point varies greatly, from 35 MPa to 21 MPa. Through the pressure observation, the roof pressure is larger but more stable and the pressure fluctuation is not large, which indicates that the roof and the upper and lower cistern under the basic static pressure state. The roof of the working face and the upper and lower groove are basically in static state.
According to the field observations, the initial caving step of roof is 42 m, the period of caving cycle is 12 m. At the malposition of 20 m, it is exactly 1.8 times of the cycle weighting of roof, which accords with the previous research conclusions.
From the mining process of working face, the pressure on the working face is not violent. Firstly, the pressure increases from the middle part of the working face, and then the upper pressure increases. Under the effective support of the working face, although sometimes the single pillar discharge phenomenon occurs, but it has little effect on the safety of the whole work face. From the collapse of the rock, the roof is layered structure, and its movement is stratified. That is, the false roof falls following the mining, the next is the direct roof falling, and the old roof falls again. The quality and strength of the support of the working face meet the requirements of the engineering quality, and the expected goal is achieved. The roof management effect is better, and the safe production of the working face is ensured.
Conclusion
Under the condition of stratified mining, when the upper layer is mined, after undergoing the process of "extrusion-unloading-support support extrusion and moving frame two times unloading". A large number of
cracks will be generated in the gangue, and the degree of fragmentation will increase. Moreover, the smaller the malposition between the upper and lower working faces is, the more serious the damage is.
Том 3, № 2 2018 Vol. 3, no. 2 2018
XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ XXI CENTURY. TECHNOSPHERE SAFETY
4 А/
ISNN 2500-1582 V
25
1O
1O
ЭКОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ И ЗАЩИТА ОКРУЖАЮЩЕЙ СРЕДЫ ENVIRONMENTAL SAFETY AND ENVIRONMENT PROTECTION
From the results of numerical calculation with 10 m, 20 m and 30 m malposition, we can know that the reasonable malposition of shaft 10 in Daanshan coal mine is 20 m.
DW14-300/100X type single prop is selected to support the composite roof. Through the field observation data and curves, it can be seen that the roof pressure is larger but more stable and the pressure fluctuation is not large, which indicates that the working face and the roof of the upper and lower groove are
basically in static state. It is technically feasible to adopt mining method with malposition of 20 m. And it can well meet the needs of safety production.
Fund Project: Youth Foundation Project of the National Natural Science Foundation of China (51404130), Doctoral foundation of the Ministry of Education (20122121120004).
References
1. SI Rong-junion WANG Chun-qiu, TAN Yun-liang. Numerical simulation of abutment pressure distribution laws of working faces [J]. Rock and Soil Mechanics, 2007, 28 (2): 351-353.
2. Han Lei. Study on Key technologies of reasonable mining in the condition of soft coal, think-hard roof and contigious ceams [D]. Hua-inan: Anhui University of Science & Technology, 2008: 36-38.
3. KANG Jian, Sun Guang-yi, DONG Chang-ji. Overlying Strata Movement Law of Ultra-Close Thin Coal Seam Adopting Simultaneous Mining Face [J]. Journal of Mining & Safety Engineering, 2010, 27 (1): 00510056.
4. SUN Chun-lin, YANG Ben-sheng, LIU Chao. 1.0 m Strata behavior regularity of 1.0 m very contiguous seams combined mining [J]. Journal of China Coal Society, 2011, 36 (9): 1423-1427.
5. CHA Wen-hua, SONG Xin-long, JI Ping. Determination on security malposition of combined mining in ultraclose coal seams under hard roof [J]. Journal of Safety and Environment, 2013, 13 (5): 0187-0190.
6. LI Jianpu, YANG Xiaobin, LIU Wen. Research on the strata pressure behaviors of full seam mined coal seam with rigid roof [J]. Journal of Safety Science and Technology, 2013, 9 (2): 18-22.
7. YAN Guo-chao, HU Yao-qing, SONG Xuan-min [etc].
Contribution
Wang Junguang, Wang Pengjin, Liang Bing, Li Cun-zhou have equal author's rights. Wang Junguang bears the responsibility for plagiarism.
Conflict of interests
The authors declare no conflict of interests regarding the publication of this article.
Theory and Physical Simulation of Conventional Staggered Distance During Combined Mining of Ultra-Close Thin Coal Seam Group [J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28 (3): 591 -597.
8. Hu Wei, Cui Dao-ping. Application of research on distributing discipline of abutment Pressure at combined mining among short distance coal seams [J]. Coal Technology, 2007, 26 (11): 41-42.
9.Zhang B.S., Kang L.X., Zhai Y.D. Definition of ultraclose multiple-seams and its ground pressure behavior [A]. Morgantown W.V. The 24th International Conference on Ground Control in Mining [C].[s.l.]:[s.n.], 2005: 110-113.
10. ZHAO Jian-ming. Study on supporting pressure of drift in short spacing extraction [J]. Ming Research & Design, 2003, 23 (2): 10-12.
11. Du Bo, CHEN Han-qiu. Similar simulation study on abatement pressure distribution at close-distance seams [J]. Journal of Henan Polytechnic University, 2006, 25 (5): 359-363.
12. Lin Yan, Tan Xue-shu, Hu Yao-hua. Exploration and discussion on the optimum handing distance of the simultaneous mining in the gently inclined contagious multi-seams [J]. Journal of Guizhou Institute of Technology, 1994, 23 (2): 33-38.
Критерий авторства
Ван Жунгуань, Ван Пенджин, Лянь Бинь, Ли Сунджу имеют равные авторские права. Ван Жунгуань несет ответственность за плагиат.
Конфликт интересов
Авторы заявляют об отсутствии конфликта интересов в этой работе.
Том 3, № 2 2018 XXI ВЕК. ТЕХНОСФЕРНАЯ БЕЗОПАСНОСТЬ Vol. 3, no. 2 2018 XXI CENTURY. TECHNOSPHERE SAFETY
ISNN 2500-1582
