Study of red-sandstone post-peak creep test in different loading rates

XIN Ya-jun; AN Ding-chao; LI Meng-yuan; HAO Hai-chun

doi:10.13225/j.cnki.jccs.2016.1455

Abstract：Due to the complex creep properties on low-strength post-peak rock,a uniaxial incremental loading creep test was conducted on two groups of nine red-sand rock specimens in two loading rates by RLW-2000 rock triaxial rheology test system.The characteristics of post-peak instantaneous and creep strain were analyzed in different stresses,the relationship between instantaneous strength and long-term one was determined,and the basic rock failure morphology was discussed in different stress stages.The results showed that in same loading,the higher the rate was,the smaller instantaneous strain change was;the more the attenuation creep-strain increment was,the smaller the isokinetic one was.With the stress increasing,the instantaneous strain reduced through reducing rapidly,slowly,and then increasing slowly,rapidly,while the post-peak creep strain increased linearly through slowly,average,and then rapidly,which had obviously three stages.The creep failure strength of post-peak rock specimens was similar,the discreteness was small,which was averagely 89.73％ of instantaneous one;Instantaneous compress specimen failed in compressing and shearing,and failure rock block was larger.Main post-peak creep failure surfaces were complex:the lower the loading rate was,the more obviously partial specimen was weaken in post-peak creep,and the instability type was mainly compressshear failurc along main fracture surface.