目前对Cosserat扩展模型的有限元分析均是运用Mohr-Coulomb强度准则，但由于Mohr-Coulomb强度准则的六边形屈服面是不光滑且有尖角，这些尖角可能会导致其应用于Cosserat弹塑性分析时的计算困难，Drucker-Prager强度准则正可被看成Mohr-Coulomb强度准则为避免这些困难而做的光滑近似，因此很有必要对基于Drucker-Prager强度准则的Cosserat理论进行研究。利用MATLAB分别编写了基于Mohr-Coulomb和Drucker-Prager强度准则的Cosserat扩展模型的有限元程序，并对在互层岩体中开挖的洞室进行了变形分析。结果表明，两种强度准则均可用于Cosserat扩展等效模型，但基于Drucker-Prager强度准则的有限元程序收敛速度更快，稳定性更好，能得到更为理想的结果。

The FEM programs of Cosserat expanded constitutive model are written by all use of the Mohr-Coulomb criterion at present. However, the Mohr-Coulomb yield surface is not smooth because of the hexagonal corners. These corners of the hexagon can cause numerical difficulty in its application to plasticity theory. The Drucker-Prager criterion can be viewed as a smooth approximation to the Mohr-Coulomb criterion to avoid such difficulty, which may be made to match the Mohr-Coulomb criterion by adjusting the size of the cone. So, there is an urgent need for extending the Cosserat theory based on Drucker-Prager criterion. Based on the above two criteria, the elastoplastic FEM programs for Cosserat expanded constitutive model are written and applied to flexural deformation analysis of the underground cave in the interbedded rock mass by using MATLAB. The analytical results show that the program is effective in analyzing the flexural deformation of underground cave in the interbedded rock mass. Most importantly, the Drucker-Prager criterion-based FEM program is observed to have a higher convergence speed and stability.