Rock improved CWFS model based on cyclic loading quantitative damage control experiment
The simplicity form and clear physical meaning of parameters are possessed by the cohesion weakening and friction strengthening(CWFS)model.However,the accuracy and applicability of the traditional CWFS model are not satisfactory.In this study,triaxial graded cyclic loading and unloading damage control tests of granite(tight crystalline hard rock)and siltstone(porous weak cemented rock)were performed.The traditional CWFS model was improved in three aspects:cohesion and friction angle equation,dilation angle equation,lateral to axial strain ratio equation.Firstly,the quantitative characterization points of the model stress level were optimized and the plastic parameters were unified to accurately obtain the quantitative results of the model parameters.Secondly,in response to the characteristic results of weakening cohesion and strengthening and then weakening friction,the strengthening and weakening control coefficients were introduced to construct nonlinear cohesion and friction angle equations.Finally,nonlinear dilation angle equations were established to account for the nonlinear dilation during the yield stage,and nonlinear lateral to axial strain ratio equations were developed to capture the significant nonlinear lateral deformation during the elastic stage before yield.Applicability verification shows that the improved CWFS model can be accurately applied to granite and siltstone,as well as Beishan granite and sandstone.The improved CWFS model reasonably describes the evolution phenomena of strain softening,dilatancy,elastic strain and plastic strain during the complete stress-strain process of rocks.Importantly,the improved CWFS model has significantly improved accuracy and applicability compared to traditional CWFS models.
rock mechanicsCWFS modelcohesion strengthfriction strengthnonlinear dilatationlateral to axial strain ratio
万方数据
维普
