Physical and elastic properties of NX-size rock core from 27 localities were Investigated in order to develop an engineering classification system for intact rock, and also to develop index proertiec related to important physical and engincerino charocteristics.Thirteen rick types are represented.Lnlcrawury tests were conducted on these rocks as follows: urni, weight, Shore scleroscope hardness, Schmidt hammer hardness, abrasion hardness, absorption, sonic-velocity stress-strain under cyclic loading to 5,000 psi. uniaxial stress-strain t-) failure, and point-load tensile strength. A total of 257 specimens with L/D ratios of 2:1 wee tetcd. Statistical studies were conducted with the Il 7094 computer to determine correlation and regression relationships for selected pairs of variables. A system of engineering classification is proposed in which rocks are classified on the basis of their strength and modulus properties either obtained directly from laboratory tests, or approximately from index properties recommended herein. Application of the proposed engineering classification system to data obtained by others is shown by individual charts for each of several different rock types.Five charts are presented for estimating the strength or modulus properties for intact rock from toe numerical indices obtained by either the Schmidt hamneri Lie Shore sclerosccpe, or the sonic pulse velocity, all used in conjunction with the unit weight of the rock.
The Rock Quality Designation (RQD) index was introduced 20 years ago at a time when rock quality information was usually available only from geologists' descriptions and the percent of core recovery. The RQD is a modified core recovery percentage in which unrecovered core, fragments and small pieces of rock, and altered rock are not counted so as to downgrade the quality designation of rock containing these features. Although originally developed for predicting tunneling conditions and support requirements, its application was extended to correlation with in situ rock mechanical properties and, in the 1970s, to forming a basic element of several classification systems. Its greatest value, however, remains as an exploratory tool where it serves as a red flag to identify low-RQD zones which deserve greater scrutiny and which may require additional borings or other exploratory work. Case history experience shows that the RQD red flag and subsequent investigations often have resulted in the deepening of foundation levels and the reorientation or complete relocation of proposed engineering structures, including dam foundations, tunnel portals, underground caverns, and power facilities.
Synopsis The frictional characteristics of minerals commonly found in rock and soil have been investigated experimentally. The test results reveal that the presence of fluids on sliding surfaces of minerals greatly increases the frictional coefficients of minerals having massive crystal structures, such as quartz and feldspar, but decreases the frictional coefficients of minerals having layer-lattice structures, such as mica and chlorite. The antilubricating action of fluids on massive-structured minerals was found to be the most pronounced when the fluids were highly polar. The anti-lubricating effect diminishes rapidly, however, as surface roughness increases. No consistent relationship was found between the polarity of a fluid and its effectiveness as a lubricant of layer-lattice minerals. The rate of sliding did not affect the frictional coefficients of quartz surfaces. However, the coefficients of friction of mica increased as the rate of sliding increased. Direct shear tests performed on Ottawa sand indicate that, apart from their possible effect on capillary forces, variations in particle surface moisture have no appreciable influence on the drained shearing resistance of soils composed of massive-structured minerals. However, the drained shearing resistance of powdered mica decreased as the surface moisture of the particles was increased. On a fait des recherches expérimentales sur les caractéristiques de friction des minéraux rencontrés dans le rot et le sol. Le résultat des essais montre que la présence de fluides sur les surfaces de glissement des minéraux augmente fortement les coefficients de friction des minéraux de structure cristallifére agglomérée tels que le quartz et le feldspath, mais diminue les coefficients des minéraux de structures à réseau à plans atomiques, tels que le mica et le chlorite. L'action anti-lubrifiante des fluides sur les minéraux à structure agglomérée s'est révélée la plus forte lorsque les fluides étaient fortement polarisés. Cependant l'effet anti-lubrifiant diminue rapidement lorsque la rugosité augmente. On n'a trouvé aucune relation conséquente entre la polarité d'un fluide et son efficacité en tant que lubrifiant de minéraux à réseau à plans atomiques. Le dégré de glissement n'affectait pas les coefficients de friction des surfaces de quartz. Pourtant les coefficients de friction du mica augmentent lorsque le degré de glissement augmente. Des essais de cisaillement direct faits avec des sables d'Ottawa montrent qu'à part leur effect possible sur les forces capillaires, les variations de teneur en eau superficielle des grains n'ont pas d’effet appréciable sur la résistance au cisaillement à l'état drainé des sols composés de minéraux à structure agglomérée. Cependant la résistance au cisaillement à l'etat drainé du mica en poudre diminue lorsque la teneur en eau superficielle des grains augmente.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.