NEW ELASTOPLASTIC SOLUTION OF ROCK CIRCULAR TUNNEL SURROUNDING ROCKMASS STRESS FIELD

Presently,in tunnel surrounding rockmass stress field, elastoplasticanalysis often uses the Mohr-Coulomb criterion,which doesnt consider the principal stress.The paper selects the II kind of rock materialin Miller,R.Ps experiment.Taking the circular tunnel as the research object which has integrity formationin rockmass.Then inferred circular tunnel newelastoplastic solution,such as the stress of surrounding rockmass,plastic area radius by using the unification theory of strength. and ,the introduction parameter,get their expression in two strength indexessystem ,fc and c,.Then,author has analyzed the relationship among strength indexs by curves.The solutions based onmodifiedFenner formulaand Kastner formulais the reduced forms of new elastoplastic solusions in b=0 situation.Finally,some new conclusions has obtained,which doesthe good guiding sense to the project practice.