1、英文原文 Study on destressing technology for a roadway driven alonggoaf in a fully mechanized top-coal caving face QU Qun-di (Schoolof Energy Science&Engineering,ChinaUniversity of Mining and Technology ,Xuzhou 221008,China) AbstractBased on the deformation characteristics of the roadways driven along g
2、oaf in fully mechanized top-coal caving faces,the author considers that it is the key to ensure the stability ofsurrounding rocks of roadway driven along goaf to control the deformation during the period affected by mining.Considering the characteristics of the roadway layout in fully mechanized top
3、-coalcaving faces,a technical scheme of destressing is put forward and the destressing effect is analyzed by using the software of Universal Distinct Element Code 3.0 (UDEC- 3.0). Keywordsfully mechanized top-coal caving,gob-side entry driving, roadwaylayout 1 Deformation characteristicsof the gob-s
4、ide entry in a fully mechanized top-coal cavingface In the light of key stratum theory and the law of overlying strata movement , we know that along the dip direction themain roof broke in coal wall of the lower district sublevel andformed a rock beam structure called big structure of surroundingroc
5、ks after the upper district sublevel is extracted forward. At thesame time , the peak of side abutment pressure is transferred to thedepth away from the periphery along the dip direction and the coalbody under the big structure lies in stress-relaxed area where thegob-side entry is laid out , as sho
6、wn in Fig.1. The stability analysisof the big structure of surrounding rocks and field surveys all showthat the deformation law of the roadway driven along goaf in fullymechanized top-coal caving faces obviously differs from other kinds of entries. The main characteristics are listed as follows1,2.
7、Fig.1 The structure relationship between gob-side entry and overlying strata in a fully mechanizedtop-coal caving face (1)During the period of roadway excavation, the deformation law of the gob-side entry in a fully mechanized top-coal caving face is similar to that of general soft rock roadway.The
8、roadway excavation plays a little effect on the stabilityof the big structure.The gob-side entry occurscertain value ofdeformationbecause the stress around the roadway changesand comes out stress concentration by roadway excavation. (2)During the period after roadway excavation and before mining eff
9、ect , the big structure of surrounding rocks is stable and the deformation around the roadway is small. (3)When the gob-side entry is affected by the mining of the current fully mechanized top-coal caving face , themain roof broke again and the original equilibrium of overlying strata is badly destr
10、oyed. The rock block A and B are inthe state of movement and instability. Especially , serious deformation of the surrounding rocks happens in the gob-sideentry due to the rotation and subsidence of the key block B and the quantity of deformation during the period affected bymining is 5-6 times as l
11、arge as that in the period of roadway excavation. 2.Destressingmechanism foragob-side entry in a fully mechanized top-coal caving face Arranging destressing entry in surrounding rocks of a roadway is an effective technical method to forwardly reduce thestress around the roadway and prevent the roadw
12、ay fromoccurring severe deformation and damage3 . In China , arranginga destressing entry above a roadway has mostly been adopted to protect some important chambers which serve the mine fora long period. The service period of an entry is relatively shorter and a great deal of capital should be input
13、 for the additional excavation of one or two destressing entries which also affects the normal production , so a technical scheme is putforward through reforming the roadway layout in a fully mechanized top-coal caving face to achieve the purpose of destressing. In a fully mechanized top-coal caving
14、 face , one or two entries for gas drainage are driven along the roof in themiddle part of the mining face (sometimes near the end of the face) . Based on the conditions of thick coal seams in fullymechanized top-coal caving faces , the destressing scheme is put forward as follows. One of the gas dr
15、ains is laid out.above the gob-side entry (here this gas drain can also be called as destressing entry).Therefore , this entry can bothachieve the purpose of gas drainage and destressing. The side abutment pressure induced by the upper face is transferredto the deeper coal body along the dip directi
16、on and the stress status of the gob-side entry s surrounding rocks is well improved Standing shot in coal body of both sides of the destressing entry is adopted ahead of the current mining face to createa destressing zone in enough width above the gob-side entry. This destressing zone can act as a c
17、ushion to absorb andlessen the action of high stress induced by the rotation and subsidence of the key block B , so the extent of stress transferto the gob-side entry decreases and the destressing effect has been achieved for the second time. As a result , the largedeformation of the rocks around th
18、e gob-side entry during the period affected by fully mechanized top-coal caving facemining is markedly reduced and the purpose to effectively control the deformation of the gob-side entry in a fully mechanized top-coal caving face is accomplished. 3.Numerical analysis of the destressing effect4 Base
19、d on the field test conditions of the destressing technology , the software of UDEC 3.0 is used to analyze themain factors which affect the destressing effect . The test conditions of Xinji Coal Mine are as follows. The average thickness and dip angle of the coal seam are respectively 7.5 m and 12 a
20、nd the Protodyakonov coefficient of the coal seam is0.7. The immediate roof and floor of the coal seam are both sandy mudstone in lower strength and the thickness of theimmediate roof is 2.0 m. The thickness of quartz sandstone main roof is 8.0 m. The buried depth of the tailentry is 371 453 m and a
21、 narrow coal pillar which is 2 3 m wide is reserved between the tailentry and the neighboring gob area.Trapezium-shaped supports are used to support the tailentry and the crossbars , legs , set spacing of the supports are 3.2 ,2.8 , 0.5 m respectively. 3.1 Influence of destressing entry location on
22、the destressing effect Because the gob-side tailentry and destressing entry are respectively laid out along the roof and floor of the coalseam, the change of vertical interval between two entries is not considered here. The gob-side tailentry and distressingentry are laid out as shown in Fig.2 to en
23、sure the integrality of the coal roof of the gob-side tailentry and avoid the trans fixion between the destressing zone and the neighboring gob area. Fig.2 Sectional view of roadway layout of the test site 1 Headentry； 2 Gob - side tailentry ； 3 Destressing entry ；4 Gas drain ； 5 Standing shot zone
