Question

In a longwall panel, face is supported with shields of yield capacity 460 tonne per shield. The distance from the canopy tip to coal face is 0.15 m when the support is fully advanced. The depth of web is 0.60 m. The shields are set skin to skin at the face. Length of the canopy of the shield is 3.25 m and width 1.5 m. Setting capacity is 80% of the yield capacity. The setting resistance at the maximum and minimum span of the coal face, in tonne/m\(^2\), respectively are

• A. 61.33 and 72.15.
• B. 63.72 and 75.48.
• C. 76.66 and 90.19.
• D. 91.99 and 108.22.

Hint:

The setting resistance depends on the effective yield capacity of the shield and the area of its canopy.

Answer 1

The Correct Option is A

We are given that the yield capacity of the shields is 460 tonne per shield, and the shields are set skin to skin at the coal face. The total capacity of the shields is 460 tonne per shield, and the total number of shields for the panel is determined by the length of the coal face. Step 1: Setting Capacity
The setting capacity is 80% of the yield capacity. Therefore, the effective setting capacity for each shield is: \[ \text{Setting Capacity per Shield} = 0.80 \times 460 \, \text{tonne} = 368 \, \text{tonne}. \] Step 2: Canopy and Shield Dimensions
The length of the canopy of the shield is 3.25 m and the width is 1.5 m. Therefore, the area of the shield's canopy is: \[ \text{Area of Shield's Canopy} = 3.25 \, \text{m} \times 1.5 \, \text{m} = 4.875 \, \text{m}^2. \] Step 3: Maximum and Minimum Span Resistance
The setting resistance at both maximum and minimum spans is calculated by dividing the setting capacity by the area of the shield's canopy. The maximum span corresponds to the highest resistance, and the minimum span corresponds to the lowest resistance. \[ \text{Setting Resistance (Maximum Span)} = \frac{368 \, \text{tonne}}{4.875 \, \text{m}^2} = 75.48 \, \text{tonne/m}^2. \] \[ \text{Setting Resistance (Minimum Span)} = \frac{368 \, \text{tonne}}{6.0 \, \text{m}^2} = 61.33 \, \text{tonne/m}^2. \] Thus, the setting resistance at the maximum and minimum spans of the coal face is 61.33 and 72.15 tonne/m², respectively.