SciTech Connect

Title: Mechanical characterization of densely welded Apache Leap tuff

Mechanical characterization of densely welded Apache Leap tuff An empirical criterion is formulated to describe the compressive strength of the densely welded Apache Leap tuff. The criterion incorporates the effects of size, L/D ratio, loading rate and density variations. The criterion improves the correlation between the test results and the failure envelope. Uniaxial and triaxial compressive strengths, Brazilian tensile strength and elastic properties of the densely welded brown unit of the Apache Leap tuff have been determined using the ASTM standard test methods. All tuff samples are tested dry at room temperature (22 {plus_minus} 2{degrees}C), and have the core axis normal to the flow layers. The uniaxial compressive strength is 73.2 {plus_minus} 16.5 MPa. The Brazilian tensile strength is 5.12 {plus_minus} 1.2 MPa. The Young`s modulus and Poisson`s ratio are 22.6 {plus_minus} 5.7 GPa and 0.20 {plus_minus} 0.03. Smoothness and perpendicularity do not fully meet the ASTM requirements for all samples, due to the presence of voids and inclusions on the sample surfaces and the sample preparation methods. The investigations of loading rate, L/D radio and cyclic loading effects on the compressive strength and of the size effect on the tensile strength are not conclusive. The Coulomb strength criterion adequately represents the failure envelope of the tuff under more » confining pressures from 0 to 62 MPa. Cohesion and internal friction angle are 16 MPa and 43 degrees. The brown unit of the Apache Leap tuff is highly heterogeneous as suggested by large variations of the test results. The high intrinsic variability of the tuff is probably caused by the presence of flow layers and by nonuniform distributions of inclusions, voids and degree of welding. Similar variability of the properties has been found in publications on the Topopah Spring tuff at Yucca Mountain. 57 refs., 32 figs., 29 tabs. « less
Authors: ;
Publication Date:
OSTI Identifier:138134
Report Number(s):NUREG/CR--5688
ON: TI91014847; TRN: 91:018451
Resource Type:Technical Report
Data Type:
Resource Relation:Other Information: PBD: Jun 1991
Research Org:Nuclear Regulatory Commission, Washington, DC (United States). Div. of Engineering; Arizona Univ., Tucson, AZ (United States). Dept. of Mining and Geological Engineering
Sponsoring Org:Nuclear Regulatory Commission, Washington, DC (USA)
Country of Publication:United States
Language:English
Subject: 36 MATERIALS SCIENCE; 58 GEOSCIENCES; TUFF; MECHANICAL PROPERTIES; MECHANICAL TESTS; YUCCA MOUNTAIN; SITE CHARACTERIZATION; MINERALOGY; CHEMICAL COMPOSITION; HYDROLOGY; HYDRAULIC CONDUCTIVITY; Yucca Mountain Project