Application of Longitudinal Vibration Theory in Manhole Settlement Study

The traffic load was simulated by stable simple harmonic load. Taking the most dangerous condition, the advantageous effect of the pipeline connected to the manhole was neglected. With the effect of soil on the manhole simulated by Voigt model, the longitudinal vibration equation of the manhole in viscoelastic soil was established considering its gravity. The semi-analytical solution in time-domain and the curve of manhole settlement were obtained with Laplace transform and inverse Fourier transform. A three-dimensional finite element model, considering the nonlinear mechanics behavior of the manhole under traffic load, was set up to validate the reliability of the theoretical method using the software of ANSYS. The finite element model result showed that the curves of manhole settlement gained from these two methods were nearly consistent, which shows that the proposed theoretical method is feasible to analyze the manhole settlement under traffic load.