The design of shallow tunnels in an urban environment requires the prediction of ground movements, settlements, and lining pressures. The behaviour of two adjacent D-shaped tunnels is not yet well understood. This paper focuses on the effect of different factors on the behaviour of two shallow adjacent D-shaped tunnels. Theses factors include shape effect, lining effect excavation sequences, soil type, and spacing between the two tunnels.

Finite element technique is used in this analysis. The soil is modeled by linear and bilinear models.

The spacing between the two tunnels, where each tunnel has independent behaviour, is determined. The soil stresses, deformations, and failure zones around tunnels due to the excavation of two tunnels are analyzed and compared with the corresponding values obtained from the case of one tunnel only. Three types of soil were considered under drained conditions.