To investigate the mechanical properties of sandy mudstone under the high temperature, the uniaxial compressive testing of sandy mudstone with the cylindrical shape of 25 mm in diameter and 50 mm in length at different temperatures (20°C to 700°C) was conducted by multifunctional rock mechanics testing machine. The stress and strain behaviors were analyzed along with failure mode. According to the results, the mechanical characteristics of sandy mudstone largely depended on the temperature, and compressive strength and peak strain of sandy mudstone grew when temperature increased from 20°C to 700°C, and compressive strength grew gradually with the increase of temperature when the temperature was not less than 300°C, and it dramatically increased to the maximum value of 252.15 MPa at 700°C from 102.83 MPa at 300°C; The elastic modulus E remained stable from 20°C to 100°C, and then it nearly increased linearly as the temperature rised when the temperature was not greater than 500°C, and it maintained a stable tendency from 500°C to 700°C; Besides, the failure mode of sandy mudstone gradually changed from tensile failure to shear-tensile failure with the increase of temperature; Lastly, thermal damage showed ‘negative’ mechanical damage of sandy mudstone, and the damage variable decreased with the rise of temperature for the temperature not greater than 500°C, and then it nearly tended to remain stable from 500°C to 700°C.

1. INTRODUCTION

The temperature is one of the main factors affecting rock deformation and strength characteristics (Chen et al., 2012; Ozguven et al., 2014; Shao et al., 2015; Tiskatine et al., 2016; Sun et al., 2016; Liu et al., 2016). The study of rock engineering under high temperature is a significant subject of rock mechanics, which plays a key role in solving engineering problems, such as underground coal gasification, deep-buried disposal of nuclear waste, geothermal resources development, in-situ heating of oil shale (Yang et al., 2014) and so on. The related mechanical parameters of rock at different temperatures are the foundation for studying the stability and security of rock engineering.

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