scholarly journals Study on Pressure Relief Technology of High-Pressure Water Jet of Residual Coal Pillar in Overlying Goaf in Close Seam Mining

2022 ◽  
Vol 2022 ◽  
pp. 1-19
Author(s):  
Shang Yang ◽  
Xuehui Li ◽  
Jun Wang ◽  
Shuhao Yang ◽  
Zhen Shen ◽  
...  

To solve the problem of strong ground pressure behaviour under a residual coal pillar in the overlying goaf of a close-distance coal seam, this paper proposes the technology of weakening and relieving the residual coal pillar in the overlying goaf by a high-pressure water jet. Based on the geological occurrence of the No. 3 coal seam and mountain No. 4 coal seam in the Yanzishan coal mine, the high-pressure water jet pressure relief technology of residual coal pillars in the overlying goaf of close-distance coal seams was studied by theoretical analysis and field industrial tests. First, the elastic-plastic zone of the residual coal pillar and the stress distribution law of the floor are obtained by theoretical analysis, and the influence degree of the residual coal pillar on the support of the lower coal seam working face is revealed. Then, a high-pressure water jet combined with mine pressure is proposed to weaken the residual coal pillar. Finally, through the residual coal pillar hydraulic cutting mechanical model and “double-drilling double-slot” model, the high-pressure water jet drilling layout parameters are determined, and an industrial field test is carried out. The single knife cutting coal output and 38216 working face hydraulic support monitoring data show that high-pressure hydraulic slotting can weaken the strength of the coal body to a certain extent, destroy the integrity of the residual coal pillar, cut off the load transmission path of the overlying strata, and reduce the working resistance of the hydraulic support under the residual coal pillar to a certain extent, which is beneficial to the safe mining of the working face.

2013 ◽  
Vol 868 ◽  
pp. 356-360
Author(s):  
Jun Liu

Apply high pressure water jet drilling and reaming integrated technique to research the technique of dip cross-cut uncovering serious outburst coal seam group; numerical simulation by FLAC3D concludes that how much the diameters be after being reamed can get relief pressure well at different hole spacing; it shows that the technique expands pressure relief range, increases the permeability of coal and improves the drainage efficient at uncovering coal area in the experiment. Improve the craft and equipment of high pressure water jet drilling and reaming integrated technique, solve the problem of coal dust extraction difficultly at the dip hole, prolong high pressure and rotating joints life; the research indicates that high pressure water jet drilling and reaming integrated technique gets well effect on uncovering coals speed and outburst prevention effect, its of promotion application value to uncovering coal safely and efficiently in mine.


2012 ◽  
Vol 577 ◽  
pp. 147-150 ◽  
Author(s):  
Yong Jiang Zhang ◽  
Xian Zheng Meng ◽  
Jian Jun Cao

Test mine is a large modern mine, the 13-1 coal-seam original permeability coefficient was low, gas pressure and content were higher, coal seam outburst danger of serious, directly extracting coal gas is difficult. Using a new type of high pressure water jet reaming technology, can achieve the expansion of borehole diameter, increase coal seam exposed area and pressure relief range, thereby improving the coal seam permeability, increased coal seam drainage radius. Investigated on the basis of determination of the original coal seam gas pressure and content of the coal extraction radius after the hydraulic reaming. Provide the basis for the seam of the test area borehole design


Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 60
Author(s):  
Lihuan Chen ◽  
Muzheng Cheng ◽  
Yi Cai ◽  
Liwen Guo ◽  
Dianrong Gao

The technology of increasing coal seam permeability by high-pressure water jet has significant advantages in preventing and controlling gas disasters in low-permeability coal seam. The structural parameters of a nozzle are the key to its jet performance. The majority of the current studies take strike velocity as the evaluation index, and the influence of the interaction between the nozzle’s structural parameters on its jet performance is not fully considered. In practice, strike velocity and strike area will affect gas release in the process of coal breaking and punching. To further optimize the structural parameters of coal breaking and punching nozzle, and improve water jet performance, some crucial parameters such as the contraction angle, outlet divergence angle, and length-to-diameter ratio are selected. Meanwhile, the maximum X-axis velocity and effective Y-axis extension distance are used as evaluation indexes. The effect of each key factor on the water jet performance is analyzed by numerical simulation using the single factor method. The significance and importance effect of each factor and their interaction on the water jet performance are quantitatively analyzed using the orthogonal experiment method. Moreover, three optimal combinations are selected for experimental verification. Results show that with an increase in contraction angle, outlet divergence angle, and length-to-diameter ratio, the maximum X-axis velocity increases initially and decreases thereafter. The Y-direction expansion distance of the jet will be improved significantly with an increase in the outlet divergence angle. Through field experiments, the jet performance of the improved nozzle 3 is the best. After optimization, the coal breaking and punching diameter of the nozzle is increased by 118%, and the punching depth is increased by 17.46%.


2021 ◽  
Vol 14 (13) ◽  
Author(s):  
Zeng-qiang Yang ◽  
Chang Liu ◽  
Feng-shuo Li ◽  
Lin-ming Dou ◽  
Gang-wei Li ◽  
...  

1988 ◽  
Vol 4 (4) ◽  
pp. 340-343 ◽  
Author(s):  
John H. Posselius ◽  
Jr.. Glenn T. Conklin

Sign in / Sign up

Export Citation Format

Share Document