Stressed-strained state of a rock mass around a working in the presence of elastic interaction between the coal seam and wall rocks

1972 ◽  
Vol 8 (3) ◽  
pp. 259-264 ◽  
Author(s):  
Yu. V. Nemirovskii ◽  
V. E. Mirenkov
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Elastic Interaction ◽  
Strained State

scholarly journals Stress and deformation analysis of gob-side pre-backfill driving procedure of longwall mining: a case study

2021 ◽  
Author(s):  
Rui Wu ◽  
Penghui Zhang ◽  
Pinnaduwa H. S. W. Kulatilake ◽  
Hao Luo ◽  
Qingyuan He
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Coal Seam ◽  
Abutment Pressure ◽  
Longwall Mining ◽  
Vertical Stress ◽  
Floor Level ◽  
Working Face ◽  
Floor Heave ◽  
Stress And Deformation

AbstractAt present, non-pillar entry protection in longwall mining is mainly achieved through either the gob-side entry retaining (GER) procedure or the gob-side entry driving (GED) procedure. The GER procedure leads to difficulties in maintaining the roadway in mining both the previous and current panels. A narrow coal pillar about 5–7 m must be left in the GED procedure; therefore, it causes permanent loss of some coal. The gob-side pre-backfill driving (GPD) procedure effectively removes the wasting of coal resources that exists in the GED procedure and finds an alternative way to handle the roadway maintenance problem that exists in the GER procedure. The FLAC3D software was used to numerically investigate the stress and deformation distributions and failure of the rock mass surrounding the previous and current panel roadways during each stage of the GPD procedure which requires "twice excavation and mining". The results show that the stress distribution is slightly asymmetric around the previous panel roadway after the “primary excavation”. The stronger and stiffer backfill compared to the coal turned out to be the main bearing body of the previous panel roadway during the "primary mining". The highest vertical stresses of 32.6 and 23.1 MPa, compared to the in-situ stress of 10.5 MPa, appeared in the backfill wall and coal seam, respectively. After the "primary mining", the peak vertical stress under the coal seam at the floor level was slightly higher (18.1 MPa) than that under the backfill (17.8 MPa). After the "secondary excavation", the peak vertical stress under the coal seam at the floor level was slightly lower (18.7 MPa) than that under the backfill (19.8 MPa); the maximum floor heave and maximum roof sag of the current panel roadway were 252.9 and 322.1 mm, respectively. During the "secondary mining", the stress distribution in the rock mass surrounding the current panel roadway was mainly affected by the superposition of the front abutment pressure from the current panel and the side abutment pressure from the previous panel. The floor heave of the current panel roadway reached a maximum of 321.8 mm at 5 m ahead of the working face; the roof sag increased to 828.4 mm at the working face. The peak abutment pressure appeared alternately in the backfill and the coal seam during the whole procedure of "twice excavation and mining" of the GPD procedure. The backfill provided strong bearing capacity during all stages of the GPD procedure and exhibited reliable support for the roadway. The results provide scientific insight for engineering practice of the GPD procedure.

scholarly journals The results of monitoring of hydroimpulsive disintegration of outburst-prone coal seams using ZUA-98 system

2020 ◽  
Vol 168 ◽  
pp. 00068
Author(s):  
Vasyl Zberovskyi ◽  
Kostiantyn Sofiiskyi ◽  
Rishard Stasevych ◽  
Artem Pazynych ◽  
Jan Pinka ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Rock Mass ◽  
Coal Seam ◽  
High Frequency ◽  
Strain State ◽  
Monitoring And Evaluation ◽  
Dynamic State ◽  
Coal Seams ◽  
Gas Dynamic ◽  
Mine Workings

The paper represents the results of monitoring and evaluation of the efficiency of hydroimpulsive disintegration of outburst-prone coal seams in the stopes of development mine workings using a system of sound detecting facilities. Methods of acoustic emission control have been considered as well as the monitoring tasks to evaluate rock mass conditions before the procedure and after it inclusive of the results of sound accompaniment of hydraulic disintegration of the coal seam. It has been determined that the higher concentration of stresses within the rock mass is, the more efficient action of high frequency self-oscillations of cavitation transmitter is on both the fissuring and changes in gas-dynamic state of the coal seam. It has been recommended to apply a mode of impulsive fluid pumping under the conditions where coal seam is in the stress-strain state.

Stressed-strained state of an artificial rock mass in the zone of a quarry near the face

1990 ◽  
Vol 26 (4) ◽  
pp. 338-343
Author(s):  
Kh. I. Aglyukov ◽  
L. M. Ivantsov
Keyword(s):  
Rock Mass ◽  
Strained State ◽  
Artificial Rock ◽  
The Face

scholarly journals STABILITY ASSESSMENT OF ADJACENT ROCK MASS IN THE DEVELOPMENT OF COALBED OUTLETS

2018 ◽  
pp. 51-59
Author(s):  
Olga G. Bessimbaeva ◽  
Elena N. Khmyrova ◽  
Farit K. Nizametdinov ◽  
Elena A. Oleinikova
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Active Phase ◽  
Geological Structure ◽  
Stability Assessment ◽  
South Side ◽  
Southern Side ◽  
The Stability ◽  
External Forces ◽  
Adjacent Rock

The problems of stability assessment of the quarry’s southern side during the development of the coal seam D6 are considered. To  assess the stability of the quarry’s southern side in the development  of coalbed outlets, modern research methods are applied: study of  the geological structure and analysis of the adjacent rock mass  state, the creation of an observation station and the production of observations, calculation of stability of adjacent rock mass of the  quarry’s south side and the research results analysis. Quarry’s south  side consists of clayey sediments up to 5 m, then siltstones and  mudstones up to 10-20 m and a coal seam with a capacity of up to  5 m. The substantiation of the calculated strength characteristics of  rocks composing the slopes of the quarry ledges, which determine the stress state of the slopes arising under the influence  of internal and external forces, is done. Instrumental observations of the laid station and the survey of cracks on the quarry’s side allowed  to determine the contours of the deformation zone and the  landslide prism size. A geomechanical model of adjacent rock mass  was created and the stability assessment was carried out for the  geological section along the line of the maximum development  depth. After additional loading on the quarry’s southern side slopes,  the safety factor of stability is nу = 1.69−173, which means active  phase termination of quarry’s side deformation and sustainable condition.

Elastic interaction of wall rocks with stowing material and the coal seam

1981 ◽  
Vol 17 (2) ◽  
pp. 156-159 ◽  
Author(s):  
V. A. Gogolin ◽  
Yu. A. Ryzhkov
Keyword(s):  
Coal Seam ◽  
Elastic Interaction ◽  
Stowing Material

scholarly journals An Influence Study of Face Length Effect on Floor Stability under Water-Rock Coupling Action

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Baojie Fu ◽  
Bo Wang
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Mine Pressure ◽  
Length Effect ◽  
Pressure Relief ◽  
Limestone Aquifer ◽  
Study Results ◽  
Face Length ◽  
The Face ◽  
Floor Stability

The Taiyuan Formation limestone aquifer and Ordovician limestone aquifer are widely distributed in the coal seam floor of coal measures in North China; the water hazard safety problem of the stope floor under the influence of mining is very prominent. The risk of the water inrush from the coal seam floor is closely related to the degree of full exploitation, so it is necessary to study the stability of the stope floor under aquifer conditions, especially the influence of the working face length effect on floor stability. Through numerical simulation of water-rock coupling action, the mine pressure behaviors of the water-resisting floor under different face lengths were analyzed based on the measured formation permeability coefficient. The Fish program was used to adjust rocks entering the plastic failure state into a strain softening model to investigate the influence of the face length effect, the damage degree of the water-resisting floor, and the morphology and deformation bearing capacity of the failure zone. The results show the following: (1) the face length effect is one of the main influence factors of the failure mode and failure degree of surrounding rocks in the stope; (2) as the face length increases, the obvious pressure relief zone of surrounding rocks presents a staged change, and the obvious pressure relief zone at the seam roof and floor is in an obvious “reverse saddle shape”; (3) the closer to the seam floor, the more remarkable the rock softening characteristic because of the compaction action of gangues caving from the roof; and (4) the rock mass close to the seam floor undergoes local tensile failure, and the water-resisting floor near the coal wall at two sides mainly bears compaction-shear action, leading to compression-shear failure of the rock mass at the floor and formation of water-conducting fractures. The study results can provide a reference for taking precautionary measures of safety mining above a confined aquifer.

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