Multiaxial Creep Testing of Rock and Concrete

Abstract

<p>The finite element method of simulating tunnel excavations in squeezing ground requires experimental data on multiaxial creep relationships and related characteristics of rock and concrete as input. A servo-controlled test frame, for applying multiaxial stress states to cubical specimens through three independent actuators, was developed. This test system allows the simulation of typical stress levels and stress paths involved during rock excavation, with continuous monitoring of loads and displacements through a data acquisition system. The overall equipment development required considerable design and assembly effort. A testing programme for concrete specimens was completed to evaluate the equipment. Finally, conclusion and recommendations were made which provide the necessary information and guidance for future testing to develop multiaxial creep relationships for rocks known to have significant time-dependent behaviour.</p>