Nonlinear mesoscale damage-plasticity coupled constitutive model for rocks and its numerical implementation
In order to reflect the compressive shear failure mode of rock in the process of compression,and to solve the problem that the original multi-scale rock damage mechanics constitutive model cannot describe the shear weakening,a new nonlinear mesoscopic damage-plastic coupling constitutive model is established in the framework of multi-scale rock damage mechanics by introducing local Mohr-Coulomb plastic yield function.The analytical solution of the constitutive model under conventional triaxial compression is derived,and the calibration method of all parameters of the constitutive model is given.The optimized semi-implicit decoupling algorithm is used to write the constitutive model into LS-DYNA material library,and the convergence and calculation speed of the algorithm are verified by unit test.The triaxial compressive mechanical properties of limestone are simulated by using the proposed meso-mechanical damage model.The numerical simulation results are in good agreement with the experimental data.The influences of the constitutive model parameters on the peak stress,peak strain and brittle-ductile transition of rock are obtained by the sensitivity analysis of constitutive model parameters.The established constitutive model does not need to introduce additional hardening/softening functions,significantly reduces the number of model parameters,and the parameters have a strict calibration method.The correlation flow law can be used to accurately describe the axial,transverse and shear nonlinear mechanical behavior.The convergence of the optimized semi-implicit decoupling algorithm is good,and the calculation process of the compiled LS DYNA solver is stable,and the calculation speed is significantly faster than that of the traditional phenomenological model of rock,which is of great significance for the practical application of the constitutive model.
rock mechanicsmicromechanicsdamage-friction coupling modellocal stress lode anglesemi-implicit decoupling algorithm
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