Local Buckling Of Corrugated Steel Plate Pipe-arch In Utility Tunnel

The pitch and depth of cross-section of corrugated steel plate(CSP)increase as the span increase for the CSP utility tunnel,and local buckling may occur in the straight portion of the deep wave section before the ultimate capacity is reached.This paper investigated the local buckling behavior of the straight portion of CSP in utility tunnel,and the theoretical formulas of local buckling load are derived.Then,considering the actual rotational restraint of corrugated portion for the straight portion and the curvature of invert for the pipe-arch,the theoretical formulas are modified.The finite element model of the global pipe-arch utility tunnel is established,and the corresponding analysis matched well with the revised formula,which validates the modified derivation.Finally,according to the yield criterion and stability criterion,the limit value of width-tothickness ratio for the straight portion of CSP are suggested to prevent local buckling of CSP tunnel,which can provide reference for the practical applications.The main contents can be illustrated as follows:(1)The simplified mechanical model is proposed for analyzing the local buckling of the straight portion of CSP,which simplified the rotational restraints of corrugated portion for the straight portion and the support of soil.The theoretical formulas of buckling load are derived for both the even and odd numbers of the half buckling wave,and the influences of parameters on local buckling load are investigated.(2)The local buckling of straight portion of CSP is furtherly studied.Considering the actual rotational restraints of corrugated portion and the curvature of invert for the pipe-arch,the theoretical formulas are modified.Results show that the actual rotational restraints of the straight portion are negative,and the influence of curvature on local buckling load cannot be ignored.(3)The finite element model of the global pipe-arch utility tunnel is established,and the corresponding analysis matched well with the revised formula,which validates the modified derivation.(4)According to the yield criterion,the formulas of width-to-thickness ratio for the straight portion of CSP are suggested,which consider the different grades of steel and the initial imperfection.According to the stability criterion,the parameters of the buckling stress of the pipe wall in the Canadian Highway Bridge Design Code are discussed.Results show that the design value of buckling stress of the pipe wall remains unchanged as the increase of filling height and increases as the increase of elastic modulus of soil for the invert of the pipe-arch.The formulas of width-to-thickness ratio for the straight portion of CSP are furtherly simplified,which can provide a reference for the select of the size of CSP in practice.