Triaxial Compressive Strength Tests Research Articles

A microstructure-based viscoplastic model for asphalt concrete

A microstructure-based viscoplastic continuum model is developed for the permanent deformation of asphalt concrete (AC). The model accounts for several phenomena that influence the permanent deformation of AC at high temperatures. These phenomena include strain rate dependency, confining pressure dependency, dilation, aggregate friction, anisotropy, and damage. The material anisotropy was included in the model by replacing the stress invariants in the yield function with invariants of both the stress and a microstructure tensor, which describes the aggregate orientation distribution. The components of the microstructure tensor were determined using image analysis techniques (IAT) conducted on digital images taken from two-dimensional cut sections of AC. Furthermore, damage was included in the model based on the effective stress theory to account for crack and air void growth that significantly reduces the load-carrying capacity of the material. Experimental data from triaxial compressive strength tests conducted at five strain rates and three confining pressures were used to develop a methodology to determine the material parameters that characterize AC permanent deformation. The model predictions were in a good agreement with the experimental measurements.

Geotechnical rock-mass evaluation of the Anamur dam site, Turkey

This paper describes a feasibility-level geotechnical evaluation carried out at Anamur dam site, in terms of stability analysis of dam foundation, excavation slopes and a diversion tunnel. The proposed Anamur dam will be built across the Anamur river on the Alanya metamorphic series which consists of phyllite, schist and slate units at the site. Geotechnical investigations included drilling for core, pumping tests, sampling for laboratory testing, and a detailed discontinuity survey. Uniaxial compressive strength, density, triaxial compressive strength and direct shear tests, have all been carried out in the laboratory. Discontinuity data are processed for the determination of dominant sets and for the rock mass characterization in terms of classification systems. Evaluation concentrated on kinematic analysis in slope stability, Goodman's bearing capacity approach in foundation stability and rock mass classification for diversion tunnel stability assessment. The geotechnical evaluation of the proposed dam and reservoir site established that there will be no stability problems. Detailed geotechnical investigations are required for the final design of this project.

Thermo‐Mechanical Behavior of Seafloor Sediments

A laboratory investigation of the thermo‐mechanical response of deep ocean sediments has been performed. The study encompasses the range of thermal loadings expected for the emplacement of a canister of radioactive waste approximately 30 m below the seafloor in deep ocean waters. The experimental program included mechanical and thermal consolidation, undrained triaxial compressive strength and constant stress level creep tests on seafloor sediments over a temperature range of 4–200 °C.