Notes on Stress, Strain, and Joints

Citations Over Time

Abstract

Patterns composed of two sets of slip joints are useful to the geologist as a record from which to interpret the state of stress or strain in the observed rock mass at the time of its failure. For such an interpretation it is necessary to decide whether the direction of greatest compressive stress, or of greatest shortening, be taken as the bisectrix of the acute, or that of the obtuse angle between the joints. Theoretical considerations of failure by slipping along two sets of planes at approximately 90° to one another bring out two general theories. One, called the "stress theory" in this paper, concludes that these planes form acute angles facing the direction of greatest compression; and the other, called the "strain theory," that these planes form obtuse angles facing the direction of greatest compression. An analysis of experimental data and field evidence in the light of the factors evaluated by these two theories suggests the following rule: that in incompetent beds the strain theory be used, i.e., that the direction of greatest shortening be interpreted as bisecting the obtuse angle between the slip joints, and that the joint patterns in competent rocks be used with caution in this connection. Some remarks on the nomenclature of joints are added, suggesting that joints be classified as "slip" or "rip joints" instead of as "shear" (compression) or "tension joints." Also the general relations of stress and strain are discussed, emphasizing the distinction between causal and internal stresses and the fact that some independent evidence is necessary in order to determine the causal stress from the internal stress or strain condition recorded by the rock structures.

Related Papers

• → Slip resistance testing of shoes — new developments(1983)139 cited
• → Electrokinetic flows over inhomogeneously slipping surfaces(2008)114 cited
• → Unconstrained slip mechanics and stepping reactions depend on slip onset timing(2021)24 cited
• → Development of a novel biomedical device for shoe traction safety characterization(2023)5 cited