关键词: nonuniform rational Bspline, meshfree method, elastoplasticity, tunnel structure

Abstract:

In this study, a fast and stable elastoplastic analysis method using nonuniform rational Bsplinebased meshfree (NURBSMF) method is proposed to address issues related to modeling and analyzing heterotypic tunnel structures and the limited accuracy and low robustness of various numerical simulation methods. The proposed method is then used to calculate the plastic zone of the horseshoeshaped tunnel structure. The NURBSMF method leverages the merits of NURBS parameterization to represent geometry, enabling fast modeling of heterotypic structures. Node mapping and structural discretization are automatically implemented through mapping rules from the canonical parametric domain, greatly streamlining the preprocessing and analysis in numerical modeling. Elastoplastic governing equations are derived in the framework of meshfree methods and NURBS mapping rules. Thus, an improved NURBSMF elastoplastic method is proposed for fast and efficient elastoplastic analysis of tunnels with heterotypic crosssections. The proposed method provides a new node/integral generation method that eliminates the need to cut integral elements near the boundary, resulting in no discarded invalid integral points. Compared with other meshfree methods, no extra numerical cost is incurred. An advanced algorithm is developed based on the NURBSMF elastoplastic formulations and the NewtonRaphson iterative method, optimizing the modeling and computation of heterotypic tunnel structures. Benchmark and engineering numerical tests illustrate the conciseness, robustness, and accuracy of the proposed method, which is also applicable to other engineering scenarios.