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/unr 1991 Cyprxc TCC • Pralirtwn ojSubtidcnn E/feru ~ 1 <br />Caved Zone: This zone is mechanically charatteriud as rubbiliud and extends from [he <br />coal seam a distance 4-6 times the mined coal thickness. <br />Fracture Zone: This zone is mechanically chantterized by signifiant fncturing and <br />extends approximately 30~i0 times the mined coal thickness. <br />Intermediate Zone: Referred to as the °aquiclude' zone by Rauch (1989) and the zone <br />of `composite beams' by Hasenfus (1988). This zone is mechanically characterized by~ <br />minor bed separation and the absence of vertical fracture dilation and extends from the <br />fracture zone to within 50 feet of the surface. <br />Surface Zone: This uppermost zone is mechanically charatterized by vertical fntturing J <br />(or existing fracture dilation) azsodated with tensile strains induced by mining. The enact <br />nature of the deformation is a funttion of the surface geology and the magnitude of <br />mining induced displacements (Whittaker and Breeds, 1977). <br />2.0 APPROACH TO PREDICTING SUBSIDENCE IN THE FISH CREEK AVF <br />STUDY AREA <br />Our approach to subsidence prediction for the Fish Creek AVF impacts study has involved: <br />1. A review of the original subsidence predittions for the initial mine permit. <br />• <br />2. Analysis of survey data collected for three monitoring lines representing panel <br />star[ and transverse profiles; <br />Line 12000E: This line extends from 900 feet north of Panel 1's tailgate <br />(Monument SM72) a distance of 2400 feet south to a point 100 feet beyond <br />Longwall Panel 2's headgate (Monument SM50). This line waz used to analyze <br />subsidence over Longwall Panels 1 and 2 due to Panel 1, Panel 2, and Panel 3 <br />undermining. <br />Line 6LCL: This line extends from 1200 feet west of Panel 1's start room <br />(Monument SM98) a distance of 2000 feet east along Panel 1's centerline (to <br />Monument SM78). <br />Line 4LCL: This line extends from 650 feet west of Panel 3's start room <br />(Monument P92) a distance of 2800 feet east along Panel 3's centerline (to <br />Monument P120) <br />3. Development of start and transverse subsidence, displacement and strain profiles <br />for the seletted survey lines. <br />4. Comparison of measured profiles with the Subsidence Engineer's Handbook <br />(NCB, 1975). <br /> <br />5. Prediction of star[ and [ransverse profiles for Panel 5, and Panels 5 and 6. <br />.1 CZ /nc. • P.O. Box 774018 ' Srmmlmt SPnngs, Colorado 80477 • (303J879~6160 <br />