Frictional Properties of Cedar City Quartz Diorite
Abstract
A field and laboratory program was conducted to determine the frictional and deformational properties of Cedar City quartz diorite. In-situ tests on joint surfaces ranging in area from 22 to 795 square inches indicate a decrease in initial and residual shear strengths with increasing area. Laboratory data should be scaled appropriately depending on joint size, wave length and amplitude as compared to in-situ joints. Strength and modulus of jointed and unjointed specimens are similar until shearing begins when the strength of joint samples decreases. Field tests on specimens with single and multiple joints oriented at different angles to the axial stress indicate a significant geometric effect and that unfavorably oriented joints determine the shear strength of the entire joint block until that joint interacts with adjacent blocks. Servo-controlled direct shear laboratory tests on natural and artificially prepared joints over a normal stress range of 60 to 1500 psi indicate that there is a geometric effect with roughness but that this may be overridden by a contact area and/or asperity strength effect present in natural joints. This gives rise to a lower friction angle than in smoother but perfectly mated artificial surfaces. Initial and residual coefficients of friction are a function of both normal stress and displacement.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1972
- Accession Number
- AD0907151
Entities
People
- A. D. Black
- F. J. Bonney
- H. R. Pratt