Deformation and Failure Behavior of Rock-Filled Concrete under Uniaxial and Triaxial Compression at Seismic Strain Rates

This study investigates the dynamic behavior of rock-filled concrete (RFC) through a series of compression tests, including both uniaxial and triaxial tests conducted under varying confining pressures and strain rates ranging from 10−5/s to 10−3/s. The analysis encompasses a comprehensive evaluation of test measurements, including the complete stress–strain curves, elastic modulus, dynamic peak strength, and failure modes. The results indicate that the strength of RFC is significantly enhanced by confining pressure, and the size of coarse aggregates within the RFC notably affects its deformation and strength characteristics. RFC specimens incorporating larger aggregates demonstrate relatively lower uniaxial strength but exhibit higher triaxial compression strength under the same confining pressure. Furthermore, the study establishes strength criteria adapted for RFC under triaxial compression. Columnar failure was predominantly observed in uniaxial tests, with penetrating cracks and increased damage at elevated strain rates, while no primary tensile cracks were detected on the specimen surfaces under confinement in this study. A preliminary mesoscopic investigation is also given regarding the role of self-sustaining skeletal characteristics of rock aggregates in RFC when subjected to compression under various confinement in contrast to ordinary concrete.