Question 1: Tunnel design - 35 marks Design a (from 1st principles) drilling, charging, and timing round for a square tunnel with the following dimensions: Height 4.0m, width 9.2m in competent Sandstone. Do not make use of any computer models to complete the design. The proposed hole diameter is 43mm. Final drill hole length is 3.7 on a mechanised drill. Bulk emulsion type explosives is recommended for the design (Final in-hole density 1.13g/cc ). You may select your own initiation system /s for the design. Determine the drilling, initiation and explosives cost per m3 and compare the theoretical design costs against the actual result's underground. Average overbreak is 17cm for the side walls and 22cm for the hanging wall. Assume a drilling cost of R57.50 per metre and the bulk explosives cost of R10.75 per kilogram