The Effect of Surface Loading on Wastewater Pipes in Different Implementation Methods

Because water and wastewater networks in urban areas passed in residential، commercial and densely populated places، estimation of the ground subsidence and knowledge of applied load on the pipeline are of prime importance. In this research، amount of the subsidence and the induced applied stresses on the pipelines due to surface loading in different methods- mechanized (pipejacking، Microtunnelling) and classical (Open Trench، Pitman) were investigated. UDEC software was used for the simulation of these methods. Type A of Tehran Conglomerate of HZARDARE was investigated. The results of the simulation show that the most subsidence and plastic area near the pipe is in open trench method. This is due to the infilling process of the trench with soil that has low cohesion. Maximum axial stress applied to the pipe is in pipejacking method and this is due to the complete contact of the pipe to the medium and the friction between pipe and soil. Besides that، applied displacement and stress variation on the pipe in microtunneling and pitman due to the similar geometry section in these two methods have good accommodation with each other.