"A series of modal scale, two borehole splitting test blasts was geometrically designed both with concrete and with Plexiglas. The discontinuities were all symetrically located midway between split holes and were oriented perpendicular to the desired split plane. Sand and clay filled discontinuities of 1/16, 1/8 and 1/4 inch width, and closed discontinuities were used. Both discontinuity frequency and width generally reduced the maximum successful split-hole spacing. The regularity and integrity of the split profile became poorer as the discontinuities were closer to the boreholes and the discontinuity width became greater, due to the cratering effect which occurred from the borehole to the near discontinuity. The discontinuities with rough planes tended to direct the path of the split and affect the split profile.
High speed photo elastic Plexiglas model tests indicated that radial cracking around boreholes was initiated by the dynamic shock waves and then extended by the rapidly expanding explosion gases. Shock waves were delayed and attenuated across discontinuities. Long cracks were created preferentially towards but stopped at, the neighboring discontinuities. In order to avoid the cratering effect and ensure the regularity and integrity of the final rock face, split holes should be located a distance away from discontinuities located perpendicularly across the desired split plane"--Abstract p. ii
Paul Nicholas Worsey
Charles J. Haas
Peter G. Hansen
M.S. in Mining Engineering
University of Missouri--Rolla
xiii, 116 pages
© 1986 Shijie Qu, All rights reserved.
Thesis - Open Access
Print OCLC #
Qu, Shijie, "Experimental investigation of the effect of geological discontinuity conditions of rock splitting by blasting" (1986). Masters Theses. 415.