The design of shallow tunnels in an urban environmentrequires the prediction of ground movements, settlements,and lining pressures. The behaviour of two adjacentD-shaped tunnels is not yet well understood. This thesisfocuses on the effect of different factors on the behaviourof two shallow adjacent D-shaped tunnels. These factorsincluded shape effect, lining effect, excavation sequences,soil type, and spacing between the two tunnels. Finiteelement technique was used in these analyses. The soil wasmodeled by linear and bilinear models. This research wasbased on a two dimension finite element analysis utilizinga FORTRAN computer program .An individual D-Shaped tunnel is studied. Theobtained results were compared with the results of circulartunnel under the same conditions. Thus, the shape effectwas determined. The spacing between the two tunnels, whereeach tunnel had an independent behaviour, was determined.The soil stresses, deformations, and failure zones aroundtunnels due to the excavation of two tunnels were analyzedwith multiple published experimental data of different compressors.Moreover, the results are also compared with multiple theoretical modelsproposed by other authors. The models are used to simulate theperformance of multi-stage centrifugal compressors. In real operatingconditions, the fertilizer sector was selected where multi-stage centrifugalcompressors are used.o.11