1、翻译部分 第18页外文原文JOURNAL OF COAL SCIENCE&ENGINEERING(CHINA) ISSN 1006-9097pp 28-31 Vo1 .13 No.1 Mar. 2007Study on the characteristics of ground pressure behaviors in working face with great mining height at different advance speeds by similarity model experimentHUA Xin-zhu(华心祝)1，ZHANG Jin-long(张金龙)2，XIE
2、 Guang-xiang(谢广祥)1(1. Dept. of Resource Exploitation and Management, Anhui University of Science and Technology, Huainan 232001, China;2. College of Civil Engineering, Hohai University, Nanjing 210098, China)Abstract Presently most of research results on strata behaviors were concluded under the nor
3、mal (moderate) advance rate conditions. Comparing with normal advance rate, fast advance rate and slow advance rate may cause some new changes of strata behaviors. The characteristics of ground pressure behaviors in working face with great mining height at different forward speeds were studied by si
4、milarity model experiment in laboratory. Its conclusion provides a theoretic basis for ground pressure controlling.Keywords similarity simulation, advance rate, working face with great mining height, ground pressure IntroductionThe advance rate of the high-yield and high-efficiency and high-power fu
5、lly mechanized coal face is as much more several times as that of orthodox face. But the advance rate gets slow when working face encounters abnormity or its machines and electric devices failure. Comparing with normal advance rate, fast advance rate and slow advance rate may cause some new changes
6、of strata behaviors. By similarity model experiment in laboratory, the characteristics of ground pressure behaviors in working face with great mining height at different forward speeds are studied in this paper. Its conclusion may provide a theoretic support for ground pressure controlling. 1 The pr
7、ototype geologyThe prototype is the working face No.1215(3) in Zhangji coal mine, Huainan. This working face locates -600 m level in the mine. The elevation of the working face is from -410 m to -570 m and the face length is 200 m. The C 13-1 coal seam is excavated in this working face and its thick
8、ness is from 3.6 m to 4.2 m, the average is 3.9 m. the dip angle of the coal seam is from 6 to 10, the average is 8. The value of Protodyakonv coefficient of coal strength is from 0.7 to 1.2. The coal seam occurs steady and its texture is simple. The fully mechanized coal mining method with great mi
9、ning height is adopted in this working face. 2 Experiment design2.1 Selection of the rig for model test The experiment was conducted on the plane stress rig. The height of prototype is 100 m, including 10 m bottom bed, 3.9 m coal seam and 86.1 m top cover. The size of model is: lengthwidth height=3m
10、0.3mlm.2.2 Metering equipments and measuring points arrangement (1) Measuring points arrangement Stress measuring points and displacement measuring points are laid in the model. There are 36 stress measuring points which were set in the coal seam, the immediate roof and the main roof respectively fo
11、r observing the characteristics of stress change at different forward speeds. There are 9 displacement measuring lines, including 18 measuring points which were set in the immediate roof and the main roof respectively for observing the characteristics of the displacement and falling rate of overlyin
12、g strata at different forward speeds. (2) Metering equipmentsThe BW-15 tinsel micro-dynamom are used for observing the characteristics of stress change in coal petrographic mass. It is a disk. Its diameter is 28 mm and its thickness is 7 mm. The YHD-50 electric- resistance deform are used for observ
13、ing the characteristics of the displacement of overlying strata. The data are collected by the YJD-27 strain gauge, the YE2532 data-collection system and computer in the experiment. 2.3 Excavation simulationThe 30 m coal pillar is retained respectively at the left and right excavation boundary in or
14、der to reduce the boundary effect. Three different advance rates are simulated in the model. They are slow advance rate (2.4 m/d), normal advance rate (4.8 m/d) and fast advance rate (9.0 m/d). Working face advances in 80 m at each forward speed, so working face advances in 240 m together.2.4 Observ
15、ation contentIn this experiment, the weighting length of main roof, roof subsidence, falling rate, influence area and the location of peak value of the front abutment pressure and the factor of stress concentration are observed at different forward speeds.3 Test results and analysis 3.1 The characte
16、ristics of roof caving at different forward speeds (1) Normal advance rate With the advancement of working face, the main roof span increases continuously. The main roof ruptures and falls after working face advances in 26 m. Then, the main roof falls periodically and the periodic weighting length of mai
