Mining Engineering Commons^™

Penetration In Granite By Jets From Shaped-Charge Liners Of Six Materials, Ronald R. Rollins, George Bromley Clark, H. N. Kalia

Mining Engineering Faculty Research & Creative Works

A new application of theory for three-dimensional collapse of conical liners shows why the two-dimensional analysis may offer a good approximation. Shaped-charge design parameters and rock target properties were investigated to determine their effects on penetration and breakage. Several metals, liner thicknesses, cone angles and standoff ranges for each were investigated. Effective standoff is greater for aluminum than more dense metals. Jets from the 60° monel, brass and steel liners gave the deepest penetration in granite. Jets from copper and brass liners gave equal penetration for 42° apex angles. Liners containing zinc produced small slugs or none at all. The …

An Investigation Of Combined Thermal Weakening And Mechanical Disintegration Of Hard Rock, George Bromley Clark, T. F. Lehnhoff, Vernon Dale Allen, Mahendrakumar Ramkrishna Patel

Mining Engineering Faculty Research & Creative Works

"The research under modified Contract No. H0220068 has been devoted to experimental thermal-mechanical fragmentation of Missouri red granite in place, and to supporting theoretical analyses. The results of the previous year's experimental work showed that thermal stresses are several times more effective in fragmenting hard rock when they are created within the rock rather than upon the surface. Also, large blocks {4-foot cubes) are not adequate to simulate the response of in situ rock.

Based upon laboratory tests an experimental round was designed analogous to an explosive blasting round with coiled wire heating elements placed in drill holes. Three displacement …

Combined Thermal Weakening And Mechanical Disintegration Of Hard Rock, George Bromley Clark, T. F. Lehnhoff, Gary F. Fenton, M. R. Patel, Jaw K. Wang, Vernon Dale Allen

Mining Engineering Faculty Research & Creative Works

This investigation of the combined effects of thermal weakening and mechanical disintegration (thermomechanical fragmentation) was initiated with a view toward better understanding of the processes required for more rapidly and economically fragmenting or excavating hard rock. Boring machines for utility tunnels, transportation tunnels or mining operations may be able to utilize the advantages of processes such as thermomechanical fragmentation. Secondary fragmentation or rock crushing processes also can conceivably employ the data obtained from this study.