Experimental investigation on the strength，deformation and failure characteristics of sandstone under true triaxial compression

It is of great significance to predict and evaluate the stability of underground rock engineering scientifically and accurately to study the strength, deformation and failure behavior of rock under the true triaxial stress condition. This experiment conducts a thorough and systematic study on the strength, deformation and failure characteristics of sandstone by using the self-developed true triaxial electro-hydraulic servo test system and CT scanning technique. Results have been drawn: With the intermediate principal stress increasing, the peak strength of sandstone firstly increases and then decreases. Owing to the increasing intermediate principal stress, the deformation along the direction of the intermediate principal stress is gradually suppressed, while the lateral expansion is mainly along the direction of minimum principal stress and it shows a decreasing trend of expanding and then increasing obviously. The intermediate principal stress gradually evolved into damage from protection on the rock. Under the true triaxial stress condition, there are two regular fracture surfaces which strike along the Direction of applied σ2 and dip towards σ3 in the rock specimen. The fracture surface area decreases firstly and then increases with the increase of the intermediate principal stress. The results are important to further understanding in the mechanical behavior and failure characteristics of sandstone under the true triaxial condition. © 2019, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.