Evaluation and improvement on analysis of plastic zone in roadway surrounding rock under unequal compression in two directions
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Graphical Abstract
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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*
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