Prediction of deformation safety and reliability of utility tunnel in creep stratum with spatial variability
Based on the statistical analysis of soft soil layer in Suqian,the truncated normal distribution function of the bottom elevation of soft soil layer along the axial of the utility tunnel is obtained.Considering the spatial variability of the bottom elevation and the heterogeneity of creep parameters of soft soil layer,Monte Carlo method is introduced to establish a stochastic finite element simulation method for safety prediction of utility tunnel during operation,and the influence of supporting structure on the safety of utility tunnel is analyzed.Combined with the allowable tensile stress design indexes of utility tunnel,the design method of deformation safety and reliability of utility tunnel in operation period is proposed.Finally,the influence of different widths of utility tunnel on the safety of utility tunnel is analyzed.The results show that the spatial variability of soft soil layer has a great influence on the maximum equivalent stress of utility tunnel during operation.The support structure can greatly improve the safety of utility tunnel.When the reliability is 0.9,the control value of the maximum tensile stress of the utility tunnel is 1.004 1 MPa under the condition of retaining the support structure,which is 36.53％ lower than that of 1.582 2 MPa when the support structure is removed;when the reliability is 0.9,the control value of the maximum differential settlement of the utility tunnel is 2.39 mm,it is 67.92％ smaller than 7.45 mm when the support structure is removed.The overall width of the utility tunnel has an effect on the maximum tensile stress of the structure.The larger the width,the gentler the cumulative probability curve of the maximum tensile stress of utility tunnel,and the greater the risk.
utility tunnelreliabilitystochastic finite elementcreepspatial variability of soft soil
NETL
NSTL
万方数据
