RESEARCH FOR NONLINEAR DAMAGE CREEP CONSTITUTIVE MODEL OF SOFT ROCK

Based on the nonlinear damage creep characteristics of rock and damage variable, a new nonlinear damage creep constitutive model of soft rock is defined in series with the improved Burgers model, the traditional Hooke model, St.Venant plastic substance, and a nonlinear viscosity resistance introduced to improve the Burgers model. This new nonlinear damage creep constitutive model can suitably explain the soft rock mass deformation in engineering. A series of uniaxial compression creep tests were performed to study the creep damage characteristics of typical soft rock mining samples in NO.2 mining zone of Jinchuan Group Ltd. using the increment step loading and single-step loading. The results of creep experiments and nonlinear damage creep constitutive model results are very consistent in this study. The new model not only can reflect the whole process of rock creep, but also can reasonably describe the soft rock under different initial stress creep damage, stable state creep damage and accelerated creep damage. Therefore, the new nolinear creep damage model is a reasonable reference model for the research of soft rock creep.