Abstract:
Basedonthespeciallateralpressurecoefficientsof1,theradiusofsurroundingrockplastic zoneobtainedbyapproximateimplicitmethodhasalargetheoreticalerrorcontrastedwiththecorre⁃ spondinganalyticalsolution of the mature axisymmetric plane strain theory*In order to improve this shortcoming,fromtheexistingestimationmethodforsurroundingrockplasticzoneradiusonhorizontal axisandbasedontheformulasofplasticzoneunderaxisymmetricstressfieldandassumptionofthe constanttotalcollectiondegreeoflineloads,theapproximateanalyticalsolutionofthesurroundingrock plasticzoneofunequalstressfieldonvertical(orhorizontal) axiswasderived*Thencombiningwith shapeofplasticzonedeterminedbyapproximateimplicitmethod,theplasticzoneofsurroundingrock underunequalcompressionintwodirectionswasrelativelyaccuratelydetermined*Theproposedmethod notonlyeliminatesthetheoreticalerroroftheapproximateimplicitmethodforthelateralpressurecoef⁃ ficientof1,but also overcomes the theoretical defects of radial stress equal to zero in elastoplastic boundaryofsurroundingrockbyusingoriginalestimationmethodwithaxisymmetricstress*Soproposed methodcouldbeconsideredasarelativelyreasonableandaccurateestimationmethodfortheplastic
zoneinroadwaysurroundingrockunderunequalcompressionintwodirections*