Study on red sandstone mechanical property under different stress path by triaxial test
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Abstract
According to a large number of underground engineerings(tunnels and underground power houses e.g.) involved in geo-stress level controlling the stability of surrounding rock,through triaxial test of red sandstone in Jurassic,the paper analyses on the deformation and failure characteristics of red sandstone under different conditions by triaxial loading and unloading,and reveals the damage modes and mechanical properties difference by different stress conditions.It is showed that shearing failure is primary under loading condition and tension failure is primary under unloading condition;the strength parameter difference is obvious under loading and unloading condition.The value of cohesion C under unloading condition is less than that under loading condition,and friction angle φ under unloading condition is bigger than that under loading condition.For instance,the strength parameters under unloaded high pressure(20MPa) show that the value of cohesion C by unloading decreases 22.8 percent than loading condition;φ increases 57.2 percent.The above results obviously show differences of strength parameters by different geo-stress environment,and the weakness of strength parameters caused by unloading is very significant.
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