Effect of water pressure on mechanical behavior of concrete under dynamic compression state

This paper reports the experimental study of water pressure environment effects on the mechanical behavior of concrete under a dynamic compression state with strain rates ranging from 10(-5)/s to 10(-2)/s. The water content of concrete under different water pressure (0, 2, 5, and 10 MPa) was obtained, and the failure modes and the strength of concrete were proposed. Results show that strength and failure modes are remarkably affected by water content and strain rate. Under water pressure, the strength of concrete increases nonlinearly as strain rate rises, and the strain rate sensitivity of concrete increases with increasing water content. When the water content of concrete is higher than 1.27 times of w(s)(ac), (w(s)(ac) is water content of concrete which becomes a fully saturated state in atmospheric condition), and concrete under the fast loading results in cone-type failure (CTF). Moreover, the area of crack surface and the volume of debris shedding also decrease as both water content and strain rate increases; however, when the water content of concrete is lower than w(s)(ac) or the concrete under slow loading, slant shear failure (SSF) occurs. As explained through a basic poromechanics analysis, this dissimilarity is mainly attributed to the excess pore water pressure and the viscous stress inside the saturated concrete during fast (quasi-static or dynamic) experiments. (C) 2016 Elsevier Ltd. All rights reserved.