This study built the 3D finite difference simulation model to study the relationship of cavity parameter and underground pipeline's deformation and tensile stress on the basis of the actual principle of underground cavity evolution. The results show that with the cavity size increasing, the value of the settlement displacement, horizontal displacement and tensile stress of the pipeline is increasing. Compared with the single influence of cavity size, the coupling condition of cavity size and occupying pressure has more obvious influence on the pipeline's deformation and tensile stress. In recent years, with the development of cities, the underground space is more complex. The underground pipeline accidents and road collapses sometimes occur because of the environmental problems caused by the soil, which threat the stable operation of urban underground pipelines and road traffic safety. According to the cause of the accidents, underground cavities due to uncompacted foundation, leakage of nearby drain or soil loosing are play an important role in the damage of underground pipelines. With the growing public concern about the pipeline accidents, guaranteeing the safety of the pipeline is an important work in today's urban management. Many scholars researched the excavation and tunneling effect on pipeline[1,2], but the analysis of the underground cavities impact on the pipeline is rare[3]. This study built the 3D finite difference simulation model to study the relationship of cavity parameter and underground pipeline's deformation and stress on the basis of the actual principle of underground cavity evolution nearby underground pipeline. In addition, combined the occupying load and cavity size, researched the influential relationship of the parameter of occupying load and cavity and underground pipeline, in order to provide important reference for the prevention of hazard caused by the cavity.
