**A longwall mine is planned in Illinois. The following data are given to you.**

**Mining depth- 1000 feet**

**Thickness of near surface weak overburden- 85 feet**

**Seam thickness- 6.5 feet**

**Panel width- 1250 feet**

**Unit weight of weak rock overburden- 135 pcf**

**Unit weight of competent overburden — 155 pcf**

**Average angle of draw for weak overburden- 43 degrees**

**Average angle of draw for competent overburden- 21 degrees**

**Size of the shaft- 26 feet diameter**

**Estimated area to be protected around the shaft on the surface- 270 ft x 130 ft**

**Seam is assumed to be relatively flat.**

**You have been asked to develop the following longwall mining related and subsidence related information for permitting.**

**Longwall Mining:**

**Size of equal size pillars for development entries.****Pillar sizes for bleeder entries assuming that the first pillar adjacent to the set-up rooms is 1.25 times larger than the 2**^{nd}pillar adjacent to the first pillar. The second and third pillars are of equal size.**Assume abutment angle of 21 degrees.****Average 4-inch coal cubes strength- 3,000 psi.****USE ALPS software model for this design.****Make appropriate assumptions and justify them.**

**Subsidence Related**

**Size of protective pillar to protect the shaft and surrounding areas. Show all calculations and the shape of the protective pillar.****Width of the critical area.****Develop vertical subsidence, across the longwall panel using the NCB method.****Develop slope and curvature and horizontal strain profiles and comment on where the damage is most likely to occur.**