Crack coalescence in granite
Name
428976146-MIT.pdf
Description
Full printable version
Size
123.57 MB
Format
Adobe PDF
Checksum (MD5)
5791e6eecceff282614a7a0dcbf699d7
Author(s)
Miller, James Thomas, Ph. D. Massachusetts Institute of Technology
Advisor(s)
Herbert H. Einstein.
Date Issued
2008
Publisher
Massachusetts Institute of Technology
Abstract
This thesis experimentally investigates crack coalescence in prismatic Barre Granite specimens with two pre-cut, open flaws under uniaxial compression. Using a high-speed video system, crack initiation, propagation, and coalescence are observed. Flaw geometries are chosen to allow one to compare the results with those of studies in other materials as well as to better understand fracturing and coalescence processes. Specifically, the effect of ligament length (L), flaw inclination angle (p3), and bridging angle (a) on coalescence is investigated. The same crack types as in other materials are observed. Coalescence patterns observed fit into a previously developed framework (for molded gypsum and Carrara marble) with the exception of one new coalescence pattern. Crack processes and coalescence patterns suggest a more tensile behavior as grain size increases from gypsum to marble to granite. Similar to previous work in marble and granite, white patches are observed during compression tests. These white patches can be categorized as either diffuse or linear, with linear white patches further subdivided into two more types, namely boundary-following and through-going. The white patches are essentially process zones. The effect of water pressure on coalescence pattern is also investigated. Flaw water pressure is seen to affect coalescence in granite, although further work is needed.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.
Includes bibliographical references.
Subjects
Civil and Environmental Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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