<p>With increasing underground engineering construction, the elastic‒plastic behavior of the surrounding rock and its rupture characteristics in tunneling projects are crucial for engineering safety. In this study, a semi-analytical method of hydraulic‒mechanical coupling is proposed to comprehensively investigate the stress, strain and damage characteristics of the surrounding rock and its seepage model during tunnel excavation. A closed set of coupled equations is established by considering the elastic‒plastic behavior of the surrounding rock, the damage evolution, and the change in permeability. By quantitatively analysing the distributions of the stress, strain, damage, and permeability coefficient of the surrounding rock, the influence mechanism of these parameters on the stability of the surrounding rock was explored. The results show that a decrease in residual strength <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="603_2025_4653_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">${\sigma }^{*}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow> <mi>σ</mi> </mrow> <mrow /> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation> leads to the expansion of the plastic zone, an increase in the internal friction angle <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="603_2025_4653_Article_IEq2.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">$\varphi $</EquationSource> <EquationSource Format="MATHML"><math> <mi>φ</mi> </math></EquationSource> </InlineEquation> can slow the rate of stress decrease in the plastic zone, an increase of in situ stress <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="603_2025_4653_Article_IEq3.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="18" /> </InlineMediaObject> <EquationSource Format="TEX">${\sigma }_{o}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mi>o</mi> </msub> </math></EquationSource> </InlineEquation> leads to a decrease in the permeability coefficient in the elastic zone and an increase in the plastic zone, and an increase in the brittleness index <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="603_2025_4653_Article_IEq4.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">$\beta $</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation> contributes to a decrease in the range of the softening zone. In addition, damage and dilatancy significantly influence the permeability coefficient and hydraulic pressure distribution of the surrounding rock.</p>

A Semianalytical Elastoplastic Hydraulic‒Mechanical Model for Tunnel Surrounding Rock in the Excavation Damaged Zone

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发表日期：

2025年6月16日

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Yu Zhao,
Tao Wei,
Chaolin Wang,
Jing Bi,
Shuang Dang,
Mingxuan Shen

摘要

With increasing underground engineering construction, the elastic‒plastic behavior of the surrounding rock and its rupture characteristics in tunneling projects are crucial for engineering safety. In this study, a semi-analytical method of hydraulic‒mechanical coupling is proposed to comprehensively investigate the stress, strain and damage characteristics of the surrounding rock and its seepage model during tunnel excavation. A closed set of coupled equations is established by considering the elastic‒plastic behavior of the surrounding rock, the damage evolution, and the change in permeability. By quantitatively analysing the distributions of the stress, strain, damage, and permeability coefficient of the surrounding rock, the influence mechanism of these parameters on the stability of the surrounding rock was explored. The results show that a decrease in residual strength ${\sigma }^{*}$ $σ^{*}$ leads to the expansion of the plastic zone, an increase in the internal friction angle $\varphi $ $φ$ can slow the rate of stress decrease in the plastic zone, an increase of in situ stress ${\sigma }_{o}$ $σ_{o}$ leads to a decrease in the permeability coefficient in the elastic zone and an increase in the plastic zone, and an increase in the brittleness index $\beta $ $β$ contributes to a decrease in the range of the softening zone. In addition, damage and dilatancy significantly influence the permeability coefficient and hydraulic pressure distribution of the surrounding rock.