Abstract：In order to study the evaluation method of influence of deep excavation on adjacent buried utilities the influence of excavation on adjacent pipelines with varied diameters is analyzed by FLAC3D. The results indicate that pipeline diameter is important to the interaction between pipeline and soil；When pipeline diameter is less than 400 mm，the pipelines have the same displacement as surrounding soil；when the pipeline diameter is larger than 400 mm，the interaction between pipelines and soil should be taken into account. Furthermore，the maximum value of curvature，angle of rotation，stress and moment of flexure of pipeline all appear at the corner of pit with 20% excavation length. Based on the numeral analysis，a simplified method for calculating deformation and internal force of pipelines with small diameter and the evaluation grade of pipeline safety are put forward.
