1. Department of Airfield and Building Engineering，Air Force Engineering University，Xi’an 710038，China；
2. COLLEGE of Mechanics and civil architecture，Northwest Polytechnic University，Xi’an 710072，China
Abstract：By using the hydraulic and servo-controlled pressure testing machine and the split Hopkinson pressure bar (SHPB) with a diameter of 100 mm, the splitting tensile tests of sandstone with different moisture contents and cycles of freeze-thaw were carried out to study the static and dynamic mechanical properties of the sandstone. Then the mesostructure of fracture was analysed base on microscale by pictures obtained through the scanning electron microscope(SEM), tensile failure rules of red sandstone was acquired by the quantitatively processing of fracture network. The results indicate that, the tensile strength of red sandstone decreases with the increase of moisture contents and cycles of freeze-thaw, and the dynamic tensile strength exhibit obvious strain rate hardening effect. The softening coefficient and the coefficient of frost resistance of red sandstone are defined with the dynamic tensile strength, the softening coefficient decreases with the increase of strain rate, while the coefficient of frost resistance increases with the increase of strain rate. Three main fracture microstructure characteristics, corresponding to different macromechanical properties. In the area of the fracture network as damage variable, the rock internal damage extension was analyzed by exploring water-strain rate effect and freeze-thaw-strain rate effect in the dynamic splitting tensile damage, and then analysis of the dynamic fracturing mechanism of red sandstone under different conditions. It is significative for engineering construction and maintenance in cold regions.
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