Failure Envelope of an Underground Rectangular Pipe Gallery in Clay under Pipe-Soil Interactions

Urban underground comprehensive pipe galleries (referred to as UCPGs) often have large rectangular cross sections and are now widely used as underground tunnel spaces for accommodating various engineering pipelines used for power, signal communication, gas, oil, heating, water supply, and drainage channels in China. The force-displacement relation for a pipe-soil interaction is very important since it can be used to evaluate the pipe behavior under various conditions. Conventional theoretical analysis methods are usually proposed for circular cross-sectional pipes, while few methods have been presented for UCPGs with large rectangular cross sections. This paper studies the two-dimensional rectangular pipe-soil interaction problem. The limit resistances of underground rectangular pipe galleries (URPGs) in undrained clay under purely horizontal and vertical loads are first investigated through two-dimensional finite-element limit analysis (FELA). Subsequently, the failure envelope of the URPGs under relative pipe-soil movement along various directions is investigated. Parametric analyses are carried out to derive the empirical equations of the limit resistance and failure envelope of the URPGs. The proposed empirical equations are verified by comparing the theoretical predictions with the FELA results and other researchers' studies, and they provide a basis for constructing the p-y relation of the pipe-soil interaction.