Structural design of oval-shaped sewer linings

This article describes a design method for oval-shaped sewer linings subject to external groundwater pressure. The beneficial interaction between the lining and the host structure is taken into account. The method is based on an approximate analytical solution of a clamped beam undergoing large deflection subjected to a uniformly distributed loading and in close contact with a rigid body. The method gives formulas for bending moment, axial force and maximal deflection. Thus the engineer is able to calculate a safety factor for strength and limit deflection. Comparisons with finite element analysis with large deflection and contact nonlinearities are presented for three different oval shapes. A calculation example is also treated.