Study on a new inversion method for non-uniform distribution of rock material parameters

Combining the digital speckle correlation method (DSCM) with the finite element model updating (FEMU) method, a new inversion method of non-uniform distribution of rock material parameters is proposed to study the characteristics of non-uniform distribution of rock material parameters and its evolution with the loading process. The non-uniform displacement field of the specimen during experimental loading is calculated based on DSCM. Based on FEMU, the experimental loading process is simulated in finite element software ABAQUS. Under the initial conditions, different material parameters (elastic modulus and Poisson's ratio) are given for each element according to Weibull distribution to calculate the non-uniform displacement field. The objective function is constructed by the difference between the experimental displacement field and the finite element simulation displacement field. The objective function is optimized and iterated by the genetic algorithm (GA) and the particle swarm optimization (PSO) algorithm to calculate the elastic modulus and Poisson's ratio of the experimental specimen. The inversion method for non-uniform distribution of rock materials is applied to the uniaxial compression experiment of sandstone, and the non-uniform distribution of elastic modulus and Poisson's ratio under different loading states is obtained. The inversion method for non-uniform distribution of rock material parameters proposed in this paper provides a basis for complex experiments or structural system parameter inversion.