| The article based on the research achievements of predecessors, the pressure relif mechanism of high geostress soft rock tunnel have been analyzed, and proposed the scheme of add the foam concrete layer in the support structure to achieve the purpose of high geostress pressure relif. Based on the experimental research on the machanical properties of foam concrete, through numerical simulation research, the effects and impact factors of foam concrete pressure relief and the reasonable thickness of structure layer have been researched. The main achievements of dissertation are as follows:(1) According to the mechanical properties and deformation characteristics of high geostress soft rock tunnel. The pressure relif mechanism are proposed, which is to release the stress of surrounding rock by the allowable deformation, to make the surrounding areas stress reduced and let the tunnel achieved smoothly.(2) Based on the foam concrete has the characteristics of large deformation, applied it to the high geostress soft rock tunnel pressure relief is feasible. Through the foam concrete mechanics properties test analysis, obtained using the Crushable-Foam constitutive model for numerical simulation analysis conclusion.(3) The influence of position and machanical parameters of foam concrete support of high geostress soft rock tunnel pressure relif effect have been researched by numerical simulation test scheme. Obtained the pressure relif effect are optimum when the foam concrete layer are between surrounding rock and primary support, and it can reduce the lining thickness effectively.(4) Using the foam concrete for high geostress soft rock tunnel pressure relif sufficently, which can be reduce the lining stress and the tunnel excavation size. And obtained the optimal thickness of foam concrete and support structure layer of high geostress soft rock tunnel by numerical simulation. |
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