Experimental study on shear creep properties of mudstone of badong formation

The mudstone of Badong formation (T2b) is taken as the research object about its shear creep properties with shear creep test. Relation between shear creep, shear creep rate and different normal stresses are firstly concerned. Besides, the fast-shear and shear creep tests determine its long-term strength and shear strength indicators C, φ. Moreover, linear fit relationship τ=A+Bσ (A,B are constants) is obtained which subjects to Mohr-Coulomb criterion. Function v=Mτ+N represents relation between average creep rate and different shear stresses while v=PeQτ does for steady creep rate (M,N,P,Q are rock material parameters). In addition, instantaneous intensity which is determined by fast-shear tests is greater than the long-term strength by the shear creep tests; meanwhile, the calculations show that shear stress make more difference on cohesion than internal friction angle.