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June 1991 Cyprus TCC • Prrda<tian o~Subsdtrur EJferu ~ 6 <br />• 3.3 MULTIPLE POINT BOREHOLE EXTENSOMETER (MPBX) MONITORING <br />A Multiple Point Borehole Extensometer (MPBX) was installed over Panel 2's centerline, in <br />monitoring well 006-89-10, by the U.S. Bureau of Mines (USBM). Anchors were looted in the <br />'B' (anchor 1) and 'C' (anchor 2) sandstone, Tongue of Lewis Shale (anchor 3), Twentymile <br />Sandstone (anchor 4), and overlying Lewis Shale (anchor 5). The results of this monitoring <br />exerase were inconclusive (see Figure 14), however, the USBM wncluded that the overlying <br />strata sued together with no evidence of bed separation (Haramy, 1992). <br />4.0 PANEL 5 SUBSIDENCE PREDICTION <br />Panel 5's start room as shown on Map 1, Longwall Layout Plan, is located beneath the eastern <br />boundary of the Fish Creek AVF and will be the first longwall panel to influence [he study <br />area. As Panel 5's start room is located approximately 700 feet west of, and behind Ehe start ~ <br />room for Panel 4, it will not be influenced by the adjacent excavation in the area of the Fish <br />Creek AVF. <br />Our approach to predicting subsidence from this initial undermining therefore involves: <br />Calculating the transverse subsidence profile using data from Survey Line 12000E <br />corresponding to Panel 1 undermining, and a transverse draw angle of 17 degrees <br />• 2. Calculating the start rubsidence profile using a value for maximum rubsidence for <br />Survey Line 6LCL corresponding to Panel 1 undermining, and a start profile draw <br />angle of 15 degrees <br />3. Constructing rubsidence contours by interpolation between start and transverse <br />profile da[a <br />Baseline data for Panel 5 and data points for the predicted transverse subsidence and start profiles <br />are shown in Tables 10 and 11 respectively. Corresponding contours are plot[ed on Map 2, <br />Subsidence Associated with Panel 5. Subsidence associated with Panel 5 within the designated <br />Fish Creek AVF is negligible with a projected range of 0 to 6 incltes. <br />5.0 PANEL 5 AND 6 SUBSIDENCE PREDICTION <br />Pane16's start room is located direct] beneath the Fish Creek AVF (Map 1). As Panel 6's start <br />room is orated behind Panel 5's start room, it will not be in uence y the adjacent eaavation <br />Eor a distance of approximately 1000 feet of face retreat. However, once Panel 6 emerges from <br />behind Panel 5's start room, increased deformations will occur over bo[h Panel 5 and Panel 6. <br />Our approach to predicting subsidence from Panel 6 undermining therefore involves: <br />1. Prediction of the increase in Panel 5 star and transverse subsidence profiles using <br />data from Survey Line 12000E for Panel 1, corresponding to Panel 2 mining (e.g., <br />a maximum subsidence of 53 inches, start and transverse draw angles of 15 and <br />• 17 degrees respectively). <br />.1 CZ lnc. " P.O. Boz 774018 ` Strambasr Springy, Colorado 80477 • (303J879~6260 <br />