这是ABAQUS在岩土工程中应用一书的源代码，对于二次开发材料很有用-this is a book about the applicant of abaquse in geotechnical engineering.it is important in usage

Drucker-Prager准则是岩石力学中最为重要的强度理论之一，在岩土工程研究中，尤其是在岩土工程数值分析中应用极为广泛。(Drucker-Prager criterion is one of the most important strength theories in rock mechanics. It is widely used in geotechnical research, especially in numerical analysis of geotechnical en