Comparison of Sandstone Damage Measurements Based on Non-Destructive Testing.

Duohao Yin,Qianjun Xu

doi:10.3390/ma13225154

Abstract

Non-destructive testing (NDT) methods are an important means to detect and assess rock damage. To better understand the accuracy of NDT methods for measuring damage in sandstone, this study compared three NDT methods, including ultrasonic testing, electrical impedance spectroscopy (EIS) testing, computed tomography (CT) scan testing, and a destructive test method, elastic modulus testing. Sandstone specimens were subjected to different levels of damage through cyclic loading and different damage variables derived from five different measured parameters—longitudinal wave (P-wave) velocity, first wave amplitude attenuation, resistivity, effective bearing area and the elastic modulus—were compared. The results show that the NDT methods all reflect the damage levels for sandstone accurately. The damage variable derived from the P-wave velocity is more consistent with the other damage variables, and the amplitude attenuation is more sensitive to damage. The damage variable derived from the effective bearing area is smaller than that derived from the other NDT measurement parameters. Resistivity provides a more stable measure of damage, and damage derived from the acoustic parameters is less stable. By developing P-wave velocity-to-resistivity models based on theoretical and empirical relationships, it was found that differences between these two damage parameters can be explained by differences between the mechanisms through which they respond to porosity, since the resistivity reflect pore structure, while the P-wave velocity reflects the extent of the continuous medium within the sandstone.

Highlights

Sandstone is a natural building material and a common lithology found in the rock surrounding underground engineering sites such as tunnels and underground powerhouses [1]
parameters—longitudinal wave (P-wave) velocity-to-resistivity models based on theoretical and empirical relationships, it was found that differences between these two damage parameters can be explained by differences between the mechanisms through which they respond to porosity, since the resistivity reflect pore structure, while the P-wave velocity reflects the extent of the continuous medium within the sandstone
Three sandstone specimens that were subjected to different degrees of damage were selected, and three values for the damage variable were calculated from the three repeated measurements for the P-wave velocity, wave amplitude attenuation and resistivity

Summary

Introduction

Sandstone is a natural building material and a common lithology found in the rock surrounding underground engineering sites such as tunnels and underground powerhouses [1]. In underground rock mass engineering, various disturbances will cause damage to the sandstone. Rock damage can be measured using a damage test, which provides parameters from which damage variables can be calculated that reflect the damage and can be used to study its evolution. Mechanical parameters such as the elastic modulus and plastic dissipation energy are commonly used for defining damage variables

Methods

Results

Discussion

Conclusion