Reference no: EM132155037

Civil Engineering problems -

Problem 1) The project is in a low-silica marble formation. Company drilling experience in this area indicates that compressed-air rotary-percussion drills with 3-in. button bits can average 2.2 ft of penetration per minute. Assume that it takes 3 min to change a bit. Drilling efficiency is typically a 45-min hour. These drills use 10-ft drill steel. The best blasting pattern is 8 ft x 9 ft with 1.5 ft of sub-drilling. The average excavation depth is 12 ft. How many drills will you recommend for use on the job?

Problem 2) The project is in a high-silica rhyolite formation. Company drilling experience in this area indicates that compressed-air rotary-percussion drills with -in. button bits can average 0.6 ft of penetration per minute. Assume that it takes 5 min to change a bit. Drilling efficiency is typically a 40-min hour. These drills use 10-ft drill steel. The best blasting pattern is 6 8 ft with 2 ft of sub-drilling. The average excavation depth is 8 ft. How many drills will you recommend for use on the job?

Problem 3) A project in shale will have an average bench height of 21 ft. ANFO, specific gravity 0.90, will be the explosive used on the project. Dynamite, specific gravity 1.3, will be the primer explosive used. The dynamite comes in 10-in.-long, -in.-diameter sticks. The contractor's equipment can easily drill -in.-diameter holes. It is assumed that single rows of no more than 10 holes will be detonated instantaneously. The holes will be lined. The thickness of the lining material is in. To ease the fieldwork, all design dimensions should be in integer numbers (ft). Calculate an appropriate burden distance for the blast design.