1、 2300 单词， 11860 英文字符 ,3290 汉字 原 文 ： Study on gob-side entry retaining technique with roadside packing in longwall top-coal caving technology Abstract： Pointed out some technical difficulties of gob-side entry retaining with roadside packing in longwall top-coal caving technology (LTCT), and analyzed
2、 the function mechanism of roadside filling body. Theory analysis shows the mechanical properties of highwater material fit for the feature of deformation of gob-side entry retaining in LTCT, and gob-side entry retaining in LTCT face is one of effective ways to increase the recovery ratio of mining
3、district. Key words ： gob-side entry retaining, roadside packing, longwall top-coal caving, support resistance Introduction Now the longwall top-coal caving technology (LTCT) in China has shown its advantages such as advanced technique, small investment, low cost, high efficiency in production and g
4、ood safety and the like. The LTCT will be adopted widely in view of the abundant reserves of thick seam in China. However,the mining district recovery ratio in LTCT is still very low because of some restricts from LTCT process. The statistics shows that the coal loss caused by coal pillar is about 9
5、.5% of that of the whole district and that a great number of gate-roads by LTCT are protected by wide chain pillars, resulting a plenty of coal lost and limiting seriously the further increase of the coal recovery ratio in LTCT. According to the features of the LTCT, lots of in-situ tests and theore
6、tical researches have been done, and conclusion is of momentous significance for increasing district recovery ratio, decreasing tunnel drivage rate and releasing exca-vations replacement to realize non-pillar mining. At the same time, the sustainable development of the LTCT can be promoted further.
7、Gob-side entry retaining with roadside filling is one of the ways to realize non-pillar mining in LTCT. 1 Several technical problems (1) With the great height of coal seam mined out once, the scope of ground behaviors increase accordingly. Because of the increase of the mining height and the superpo
8、sition of the abutment pressure caused by mining from face and neighbor mined areas, the surrounding rock stress of the roadway increases, and the maximum value of it is 5 to 6 times of in-situ rocks. In LTCT, the distance influenced by the front abutment pressure of working face gets longer, moreov
9、er, the mining roadways are fully extracted in coal seam, so the ground pressure behaviors is sharp. It is well known that the roof-to-floor convergence of the gob-side entry is in direct proportion to the shearing height. When thick seam is extracted out once, the roof-to-floor convergence of the r
10、oadway is several times of multi-slicing method, and the reduction of cross section area of roadway ahead of working face in LTCT is very large. If a proper support pattern and a advance trestle timbering arent adopted, the deformation of the gob-side entry will rapidly increase and even be out of c
11、ontrol, resulting the roadway not to be used normally in next sector. (2) What is on the top of the gob-side entry is coal seam. Being low strength, the top-coal is crushed easily to fall into goaf, which often leads to a unsupported roof appearing above the roadway. So, it is anessential and diffic
12、ult issue to keep the stability of the top-coal of roadway. (3) Long-term research on the ground pressure behavior rule of gob-side entry in LTCT indicates:top-coal, immediate roof and main roof all present as overhanging beams, the bearing point of which is the coal wall. With approaching working f
13、ace, the overhanging beam turns rapidly and its subsidence is in direct proportion to the height mined out at one time.The coal wall in LTCT not only bears high abutment pressure but also as the bearing point of the mined area. Thereby, a great bulging toward the space of roadway will occur in coal
14、wall. Which causes not only a great displacement of the coal wall to take place but also increase of the swing angle of the overhanging beam, the top-coal of the roadway will subside sharply. To prevent the obvious displacement of the coal wall is the key problem to control effectively the deformati
15、on of the gob-side entry. (4) Because of the large strength of mining, the big airflow quantity required and the large room that occupied by the conveyer in working face, the end transloader and the belt conveyer, a large section area of roadway must be required to meet the need for equip-ment trans
16、portation, ventilation and walking,which makes it very difficult to retain and maintainthe roadway. (5) Both ends of face in LTCT are supported by end supports. When the working face is pushed and end supports are removed forward, the top-coal will fall immediately after mining because of its low st
17、rength, which makes it difficult to retain in advance the space for gob-side supporting zone to some extent. (6) The height of the roof controlling by roadside support is in direct proportion to the thickness of coal mined out. For ensuring to have enough support strength to cut the roof of big heig
18、ht required in LTCT,the roadside supporting zone is required to have larger width. It increases the difficulty to establish the supporting zone beside roadway. (7) Air leakage from gob-side entry along goaf side provides continual oxygen for spontaneous burn of the remaining coal in gob. So, ensurin
19、g the quality of roadside filling body is very important. 2 Technical analysis (1) The surrounding rock control of gob-side entry retaining in LTCT mainly is how to control the interior rock of roadway before or after entry retaining and how to fill after entry retaining. The quality of surrounding
20、rock control of roadway before entry retaining is directly relate to whether the gob-side entry retaining can obtain success or not. The excessive deformation of roadway before filling should be controlled,which must not only depends on the passive bearing load capacity of the support, but also make
21、s full use of the self- supported capacity of surrounding rock of roadway. The bolt (cable anchor) gauze can change the passive support to the active support and improve the stress state of surrounding rock, exerting the self-supported capacity of surrounding rock. In addition, a large enough latera
22、l force toward surrounding rock can increase the friction force among the fracture coal body, keeping the coal body in a radial continual state and maintaining surrounding rock in a high triaxial state of stress. At the same time, it is beneficial to prevent roof from separating bed early and increa
23、se the net section area of roadway. To avoid a large deformation caused by advance and lag abutment pressure of working face before or after roadside supporting, support must be strengthened within a given area close to front or rear of working face. (2) To make the top-coal above the roadway and th
24、e supporting zone beside roadway not fall and keep a good integrality, polyure-thane should be injected into the coal body of both ends of the face to reinforce the coal body. (3) To keep the integrality of top-coal in the space to be filled and to improve the load distribution of support beside roadway, the following measures can be taken: decreasing a set of support at the end-face along the side of entry retaining, matting the steel gauze in advance during mining, adding a long inclined junction timbering
