Damage evaluation and damage localization of rock

Abstract

Knowledge of damage accumulation and corresponding failure evolution are prerequisite for effective maintenance of civil engineering so as to avoid disaster. Based on statistical mesoscopic damage mechanics, it was revealed that there are three stages in the process of deformation, damage and failure of multiscale heterogeneous elastic-brittle medium. These are uniformly distributed damage, localized damage and catastrophic failure. In order to identify the transitions from scattering damage to macroscopically localized one, a condition for damage localization was given. The experiments of rock under uniaxial compression with the aid of observations of acoustic emission and speckle correlation do support the concept of localization. This provides a potential approach to properly evaluate damage accumulation in practice. In addition, it is found in the experiments that catastrophic failure displays critical sensitivity. This gives a helpful clue to the prediction of catastrophic failure.

An interacting micro-crack damage model for failure of brittle materials under compression

“…However, it is well known that under overall compression, the damage caused by micro-cracking tends to localize into various domains (see Xu et al, 2004, and the experimental observations of Paliwal et al (2006)). High-speed photographs of a damaged ceramic undergoing dynamic compressive loading (Paliwal et al, 2006) shows that the cracked zones contain an ensemble of cracks of various morphologies and sizes which might not be parallel to each other or aligned in a particular direction.…”

From imaging to material identification: A generalized concept of topological sensitivity

“…Mazars et al, 1991;Xu, 2004;Bonamy et al, 2005), the proposed developments be especially useful in breast cancer detection wherein the knowledge of the shear modulus of a lesion, (geometrically) identified via ultrasound or magnetic resonance imaging, may permit reliable differentiation between the malignant and benign growths (Sarvazyan et al, 1998;Fatemi and Greenleaf, 1998). For completeness, it is noted that the underlying idea of a nucleating inclusion, explored in this study, is similar in spirit to the recent work in Ammari and Kang (2004) dealing with Laplace, elastostatic and Helmholtz systems.…”

Relationship between load/unload response ratio and damage variable and its application

“…Hence, the relationship can instruct LURR to be used in earthquake prediction more precisely. In order to investigate the seismicity in the China mainland, the tempo-spatial scanning of LURR from November 1, 2002 to June 30, 2008 has been conducted with 12,15,18,24,30,36, 42 months as time window, 1 month as time step and the corresponding R = 70, 100, 200, 300, 400, 500, 600 km as scanning radius, respectively. Owing to the multi time windows and space windows, the tempo-spatial scanning needs plenty of computing power.…”

“…Suppose that the material follows a probability distribution function h(ε c ) in the mesoscopic level, such as the Weibull distribution [23,24]:…”