Abstract:Up to now,there is no finite element software including nonlinear large deformation theory based on S-R decomposition theorem,in which the deformation gradient F is decomposed into the addition of the deformation and the rotation by a co-moving coordinate system method. In this work,such a software system waw developed,which is named as A Software on Large Deformation Analysis of Soft Rock Engineering at Great Depth. Two work groups,worked together on the software by using finite element program generator(FEPG) developed by FEGEN Software Company. The software has the following features:(1) it includes large deformation theory based on S-R decomposition theorem first time as well as one based on polar decomposition theorem for comparison,the latter is included by most commercial finite element software;(2) three design methods for nonlinear mechanical problem,i.e. countermeasure design,procedure design and parameter design,are fulfilled here for large deformation analyses;(3) it includes generally used elastoplastic constitutive models for geomaterials and element types for supports,and therefore is fit for large deformation mechanical analyses for slope,foundation and underground engineering;and (4) it has a copyright of our own country. At present,the interface of the software has accomplished and programs of elastic and elastoplastic constitutive models based on two large deformation theories in two-dimension have been fulfilled,tested and implemented into the interface. Representative numerical examples confirm the rationality of the programs. The software will be a useful numerical tool for large deformation analyses and nonlinear mechanical design for soft rock engineering at great depth.