Laserfiche WebLink
Progress Report on Tatum House Subsidence issues Page 5 <br />April 12, 1995 <br />Allen Mine Model <br />The first step in the analysis process was to input the Woodward-Clyde -Allen Mine <br />data into the program. For comparison purposes the Profile function Method was <br />set up as a Room and Pillar model (Figure AM-1), and as a ]ongwall mode] (Figw~e <br />AM-2, then the Influence Function method was modeled transversely. (Figure AM- <br />3 ). <br /> The mine plan as calculated by the program is shown as figure AD4-4. Subsidence <br /> curves are superimposed as in Figure AM-5 and show a reasonable fit with the <br /> Profile Function room and pillar curve. <br /> Using the same parameters, a longitudinal model was calculated, Figure AM-G. <br /> Notice that it does not match the transverse model showing the different way the <br /> surface disturbance is calculated. <br />~ Next the parameters were adjusted so that the modified subsidence curve closely <br /> matches a curve drawn with actual field data, taking into account that it does not <br />~ reflect full subsidence. This was done by adjusting the angle of influence, and the <br /> edge effect, which in turn adjusts the subsidence factor. The new mine anode] is <br /> shown as Figure AM-8, and the subsidence curve is shown in Figure AM-9. The key <br /> parameter for matching was to develop a significant (measurable) amount of surface <br />~ movement 500 ft in front of the mining face, without making unrealistic changes in <br /> the angle of influence. The program does not show much sensitivity to changing <br /> subsidence factors, related to the over burden-% hardrock, changing the influence <br /> angle, or even to changing the width of the excavation. <br />~ For the model presented here, longitudinal prediction point #1 was estimated to be <br /> in the same location as Woodward Clyde surface survey line reference point 2-12 <br />~ and is located about 80 feet behind the final face location (at that date), prediction <br /> point # 6 is about 500 feet in front of the face and corresponds to Woodward Clyde <br />~ point 2-17. <br /> <br />~ Other models were constructed using the other mine panels, with generally the <br /> same results. Elevations and survey line points were measured from the report <br />~ Figures using a variable scale. The model is not sensitive to difference in <br /> measurements due to small drafting or scaling errors. The program does not <br />~ understand negative subsidence, but a close match of the curves can be made. One <br /> of the examples included with the users manual shows a negative subsidence <br /> situation. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />