Dynamic Mechanical Behavior of Dry and Water Saturated Igneous Rock with Acoustic Emission Monitoring

Jun Guo,Xianjie Du,Jian Yang,Ting-Ye Qi,Guo-Rui Feng,Jinwen Bai,Pengfei Wang,Zhen Li,Zehua Wang

doi:10.1155/2018/2348394

Jun Guo, Xianjie Du + Show 7 more

Open Access

https://doi.org/10.1155/2018/2348394

Copy DOI

Abstract

The uniaxial cyclic loading tests have been conducted to study the mechanical behavior of dry and water saturated igneous rock with acoustic emission (AE) monitoring. The igneous rock samples are dried, naturally immersed, and boiled to get specimens with different water contents for the testing. The mineral compositions and the microstructures of the dry and water saturated igneous rock are also presented. The dry specimens present higher strength, fewer strains, and rapid increase of AE count subjected to the cyclic loading, which reflects the hard and brittle behavior and strong burst proneness of igneous rock. The water saturated specimens have lower peak strength, more accumulated strains, and increase of AE count during the cyclic loading. The damage of the igneous rocks with different water contents has been identified by the Felicity Ratio Analysis. The cyclic loading and unloading increase the dislocation between the mineral aggregates and the water-rock interactions further break the adhesion of the clay minerals, which jointly promote the inner damage of the igneous rock. The results suggest that the groundwater can reduce the burst proneness of the igneous rock but increase the potential support failure of the surrounding rock in igneous invading area. In addition, the results inspire the fact that the water injection method is feasible for softening the igneous rock and for preventing the dynamic disasters within the roadways and working faces located in the igneous intrusion area.

Highlights

Igneous intrusions that penetrate rock and coal strata are a common geologic phenomenon [1,2,3]
This paper presents the microstructures and mineral compositions of the igneous rock firstly and shows the results of uniaxial compressive tests with incremental cyclic loading and acoustic emission (AE) monitoring of the dry and different water saturated igneous rock specimens
The evolution of the accumulated AE count is shown to be strongly dependent on the cycle number and water saturation level, which is explained by the evolution of the damage accumulation caused by coupled effect of water-rock interaction and the incremental cyclic loading in the igneous rock

Summary

Introduction

Igneous intrusions that penetrate rock and coal strata are a common geologic phenomenon [1,2,3]. Cyclic loading and unloading tests with acoustic emission monitoring are an effective approach to quantitatively measuring deformation and damage characteristics of various materials [11,12,13,14,15,16,17,18,19,20]. They proved that that AE technique is very effective for assessing the damage of RC columns subjected to earth quake-type loadings He et al [21] conducted a true-triaxial unloading test on limestone with acoustic emission monitoring and researched the relationship between the characteristics of rock burst and AE parameters. The evolution of the accumulated AE count is shown to be strongly dependent on the cycle number and water saturation level, which is explained by the evolution of the damage accumulation caused by coupled effect of water-rock interaction and the incremental cyclic loading in the igneous rock. Felicity Ratio is discussed to reveal the plastic deformation and stability of the igneous specimens with different water content

Experimental Conditions and Methodology

Results and Discussion

Conclusions