Abstract:The shale deformation of a given dam is the main issue of the study on underground openings and high slope,so it is important to discuss the viscoelastical constitutive model of the shale. Three drill cores of the shale are selected to make simple beams for rheological test. Ten measuring points are chosen and strain gage is fixed on each point. Concentrated load acts on the center of the beam,and corresponding time-dependent strains of the ten strain gages are measured by using strain gauge. According to the mensurated strains,the viscoelastical constitutive model of the shale is obtained by inversion and analysis shows that the model accords well with the real viscoelastical behavior of the shale.