Dynamic Evolution of Microscopic Wet Cracking Noises

TL;DR

This paper investigates the microscopic processes of water-influenced cracking by analyzing emitted noises, revealing how secondary instabilities and pore water pressure contribute to crack evolution.

Contribution

It introduces a novel experimental approach to study microscopic water-crack interactions through noise analysis, uncovering the dynamics of secondary instabilities during microcracking.

Findings

Secondary hybrid events occur during microcrack healing.

Pore water pressure increases locally during secondary instabilities.

Fast-locking phases follow secondary instabilities on microscopic faults.

Abstract

Characterizing the interaction between water and microscopic defects is one of the long-standing challenges in understanding a broad range of cracking processes. Different physical aspects of microscopic events, driven or influenced by water, have been extensively discussed in atomistic calculations but have not been accessible in microscale experiments. Through the analysis of the emitted noises during the evolution of individual, dynamic microcracking events, we show that the onset of a secondary instability known as hybrid events occurs during the fast healing phase of microcracking, which leads to (local) sudden increase of pore water pressure in the process zone, inducing a secondary instability, which is followed by a fast-locking phase on the microscopic faults (pulse-like rupture).