An experimental study of infrared radiation characteristics of sandstone in dilatancy process

Abstract

The rock failure process is always accompanied by dilatancy. This study investigated the average infrared radiation temperature (AIRT) characteristics in the rock dilatancy process. An Infrared Radiation (IR) dilatancy precursor point was found prior to the failure of the rocks under load. During the uniaxial loading process, the stress levels of upward-AIRT and downward-AIRT rock samples at the initial point of rock dilatancy were 0.74 σmax and 0.80 σmax, respectively. After rock dilatancy, the AIRT change rate of upward-AIRT sample increased by 1.48 × 10−4°C⋅s−1, and AIRT change rate of downward AIRT sample dropped by 1.29 × 10−4°C⋅s−1. From the initial point to the process reached rock failure, the AIRT change was almost linearly correlated with volumetric strain increment. Based on the IR thermogram, the IR hot spot was defined, and a new index—high temperature point scaling factor (HTPSF)—was proposed for qualitative analysis. The calculated HTPSF values of upward-AIRT and downward-AIRT rock samples at the IR dilatancy precursor point were 0.4 and 0.6, respectively. This study provides a new thought to determine the initial point of rock dilatancy.