Monitoring strata behavior due to multi-slicing top coal caving longwall mining in steeply dipping extra thick coal seam

For studying the strata behavior due to multi-slicing top coal caving longwall mining along-the-strike direction in steeply dipping extra thick coal seams, the shield support pressures of the upper and lower slices of panel 37220 in Dongxia Coal Mine were monitored using the KJ513 dynamic monitoring system. The set up rooms adopted the “horizontal line-arc segment-inclined line” form and used different types of shield supports. The results show that the strata pressure of upper slice panel 37220-1 changed slightly along the strike direction, while along the dip direction it exhibited strong to weak pressure from bottom to top. The first weighting interval of lower slice panel 37220-2 was about 60.8 m, and the average periodic weighting interval were about 22.6 m. The strata behavior of panel 37220-2 exhibited a spatio-temporal characteristic in that periodic weighting occurred first in the middle-upper part, followed by the middle and upper parts, arc segment, and finally the lower part. During the periodic weighting, the weighting interval and intensity also exhibited strong space characteristics. The average dynamic load coefficient was 1.48 and the maximum lateral load of the side shield was 20-25 MPa.