Importance of sidewall friction on manhole uplift during soil liquefaction

The friction at the interface of a manhole’s sidewall and soil is often ignored with the assumption of a fully liquefied state of granular soil. A detailed analysis of the component forces acting on a conventional manhole was carried out using centrifuge modeling. From the analysis, the sidewall friction at the interface of manhole sidewall and soil was determined and found to represent a substantial portion of residual resistance inhibiting manhole uplift despite its low magnitude relative to other component forces such as buoyancy, seepage force and self-weight of the manhole at static condition. In order to validate the importance of sidewall friction, further centrifuge tests with differing sidewall friction using sandpaper were conducted to demonstrate its contribution to the role of manhole uplift following soil liquefaction.