Experimental Study on the Influence of Water on Infrared Radiation Characteristics During Rock Failure
Authors: Chang Longfei , Chen Lu , Meng LingFeng , Li Yingjun , Li Dejian , Feng Jili 
Published: January 2025

ABSTRACT:
To monitor and predict the failure of water-bearing rock effectively, it is necessary to understand the influence of water on infrared radiation. Infrared monitoring experiments were conducted under uniaxial compression on sandstones with varying water contents. The infrared precursor information of water-bearing rocks was quantitatively analyzed, with a focus on the spatiotemporal variations in infrared radiation, temperature distribution, and energy changes during rock failure. The results indicate that water-bearing rock has significantly lower peak stress, total strain energy, and failure intensity than dry rock does, which is one reason for the reduced infrared radiation temperature (IRT). On the basis of the maximum and minimum changes in the IRT, the "ΔMax-ΔMin change characteristic" is proposed as an infrared precursor of rock failure. For dry sandstones, the precursor typically exhibits a sudden increase-sudden increase, whereas for water-bearing sandstones, it consistently shows a sudden increase-sharp decrease. Additionally, statistical analysis revealed a gradual increase in the frequency of high-temperature intervals during the failure process of dry sandstones, whereas low-temperature intervals increased for water-bearing rocks. This indicates that water reduces the infrared radiation intensity during rock loading. Elucidating the impact of water on infrared radiation is crucial for guiding the use of infrared technology in monitoring the failure of water-bearing rocks.

1. INTRODUCTION
Both the development of urban underground spaces and the continuous shift in resource extraction to deeper levels face complex geological conditions involving the coupling of ground stress and groundwater[1]. The physical and chemical properties of rocks are significantly affected by groundwater, which weakens their strength[2], and the safety of underground engineering construction is threatened. Fu et al.[3] used nuclear magnetic resonance (NMR) technology to visualize and quantify the dynamics of water infiltration and distribution initially. Combined with uniaxial compression tests and numerical simulation methods, an increase in rock water content leads to a decrease in rock strength, and the uneven distribution of water within rocks directly results in uneven rock strength. Through experimental analysis[4], it has been found that water alters the internal mineral cementation capacity, pore quantity, and pore size of rock, thereby weakening the macroscopic mechanical properties of sandstone. Impact tests on sandstones with different water contents at varying loading rates have been conducted to study the sensitivity of fracture toughness and crack propagation speed to loading rates and water content[5]. Chen et al.[6] studied the weakening effect of water on the brittleness of rocks from an energy perspective. Their research indicated that the presence of water reduces the energy storage capacity of hard rocks. Zhou et al.[7] analyzed the weakening effect of water on rocks from the perspective of energy, and the research revealed that an increase in water content reduces the energy storage capacity of sandstone. Research by Noël et al.[8] has shown that the weakening of sandstones by water is due to the reduction in fracture toughness and the static friction coefficient of the materials. Furthermore, two micromechanical models were used to better predict the weakening effect of water.