Abstract: In the design and construction of rock engineering, mechanical calculation is an important way to understand the properties of rock mass. In the rheological simulation of rockmass, mechanical parameters of constitutive model of rock mass become key factor to the accuracy of the calculation results. In this paper, on the basis of previous researches, sensitivity analysis of the mechanical parameters of viscoplastic rheological model is conducted. The parameter identification result under three confining pressures is regarded as the reference value, and each parameter of these reference values is increased by 20％, 40%, and decreased by 20％, 40% respectively. The other parameters remain unchanged. The strain value can be calculated by deduced rheological constitutive model and then the difference between calculated strain value and test strain value is obtained. According to the difference, the relative change of total error can be obtained and is used to measure the trend and degree of the deviation between calculated strain value and test strain value caused by parameter alteration. Among the 6 parameters in the sensitivity analysis, the sensitivity of E is the highest, the sensitivities of m and β are high in different regions, followed by γ,n, and g. Through the sensitivity analysis, the importance of mechanical parameters to the accuracy of calculation results are verified.

Key words: viscoplastic rheological model, mechanical parameters, sensitivity analysis, deformation modulus, strain error