Question

Question 6. An open pit is 50 m deep, bench height 10m, safety bench width 5 m, bench slope angle 60 degrees, haul road width 10m. Calculate the final slope angle if the road intersects with one bench on the final wall in the calculation section (15 marks).

Answer 1

Given the depth of pit, bench height, bench width, bench slope angle and haul road width, it is required to calculate the final slope angle.

The question is approached by first mentioning the diagram of the scenario. The final slope angle is then calculated by determining the total number of safety bench required, and the total width from road intersection to the pit base on a vertical plane. After determining the values, the angle is calculated as tan inverse based on the pythagoras theorem.

The diagram and detailed calculation are shown below:

Given Derte at Bit 5om Bench height 10m Safety hench ath S Bench Clat Angle: bo haul Paadwidth lom Bench wiAth Hat Road wdth Banch Height Now Coasidec the base triangle Cor fina Sape Angle Total depts of Pit Sa Tetal wid t from (xoad lateesection to(4)4 Pit base) Fiat Sta Ansle 1 30m tand So 30 30 teare, Fnal Stke Angle Sa