Bibliographic Citation
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Title | Formation and interpretation of dilatant echelon cracks |
Creator/Author | Pollard, D.D. ; Segall, P. ; Delaney, P.T. |
Publication Date | 1982 Dec 01 |
OSTI Identifier | OSTI ID: 6151146 |
Other Number(s) | CODEN: BUGMA |
Resource Type | Journal Article |
Resource Relation | Geol. Soc. Am., Bull. ; Vol/Issue: 93:12 |
Subject | 580300 -- Mineralogy, Petrology, & Rock Mechanics-- (-1989); CRACK PROPAGATION-- STRESS ANALYSIS;ROCKS-- CRACK PROPAGATION; COMPRESSION STRENGTH;DATA ANALYSIS;GEOLOGIC FISSURES;GEOMETRY;ORIENTATION;ROCK MECHANICS;TENSILE PROPERTIES |
Related Subject | GEOLOGIC STRUCTURES;MATHEMATICS;MECHANICAL PROPERTIES;MECHANICS |
Description/Abstract | The relative displacements of the walls of many veins, joints, and dikes demonstrate that these structures are dilatant cracks.^It is inferred that dilatant cracks propagate in a principal stress plane, normal to the maximum tensile or least compressive stress.^Arrays of echelon crack segments appear to emerge from the peripheries of some dilatant cracks.^Breakdown of a parent crack into an echelon array may be initiated by a spatial or temporal rotation of the remote principal stresses about an axis parallel to the crack propagation direction.^Near the parent-crack tip, a rotation of the local principal stresses is induced in the same sense.^Incipient echelon cracks form at the parent-crack tip normal to the local maximum tensile stress.^Further longitudinal growth along surfaces that twist about axes parallel to the propagation direction realigns each echelon crack into a remote principal stress plane.^Thus, many echelon cracks grow from a single parent because the work done in creating the array, as measured by its surface area, decreases as the number of cracks increases.^The geometry of dilatant echelon cracks may be used to infer spatial or temporal changes in the orientation of principal stresses in the earth.^43 references. |
Country of Publication | United States |
Language | English |
Format | Pages: 1291-1303 |
System Entry Date | 2001 May 13 |
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