APPCOR11673

• Permit No: C1981032
• IBM Index Class Name: Application Correspondence
• Doc Name: ROOF CONTROL DESIGN FOR 2ND EAST SECTION UNDER CURTIS CREEK VALLEY
• Media Type: D
• Archive: No

GROUND CONTROL SYSTEM
• FOR RIENAU 112 MINE - 2nd EAST SECTION
The purpose of this study is to determine to what
extent, if any, disturbance will occur to the surface and
overlying strata as the 2nd East Section of Rienau 112 Mine
advances under Curtis Creek.
A conservative, or worse case, approach is taken
in that maximum pressures and minimum strengths are used in
the calculations.
The pillars under the area to be protected are 130
feet by 60 feet solid coal on 150 feet by 80 feet centers.
This is 63% larger than the standard pillars used in the
Rienau 112 Mine. The mining heighth averages between 8 to
10 feet.
The width of the possible AVF (alluvial valley floor)
is estimated at 30 feet with Curtis Creek establishing the
approximate center line of the possible AVF. An additional
safety strip of 50 feet is added to each side of the possible
AVF. Therefore, the total width of surface to be protected is
130 feet. (Figure A) The lateral north-south width is not
• considered due to the virgin coal to the north and the barrier
pillar to the south which will be addressed later in this report.
Due to the protection of the solid coal to the North and South,
if subsidence were to occur, it would be in the center of the
2nd East Entry System. Therefore, the thickness of our burden
at the east-west edges of the protected surface area in the
center of the 2nd East Entries is used to calculate the angle
of draw width. This thickness is found to be 480 feet.
(Figure B) Using a conservative angle of draw of 30° the
width (W) of the draw area is calculated:
W = 480 ft. X tan 300 = 277 ft.
W = 280 ft.
Therefore, 280 feet are added to east-west sides of the pro-
tected surface area. Thus, the total width of the protected
area at the G seam elevation is = 280 ft. + 50 ft. + 30 ft. +
50 ft. + 280 ft. = 690 feet.
The maximum overburden to be supported within the
protected length is found to be on the east and west side of
the 690 feet length at points A and A~. (Figure B) This
depth is 550 feet. Using the standard of l.lpsi per foot of
overburdenl and correcting for difference in pillar area and
•
1SME Mining Engineering Handbook, Vol. 1, Pg. 13-37