The Safety Of Underground Pipelines Subjected To Disturbance Of Shield Tunnel Excavation

ABSTRACT: Underground pipelines play an important role in modern society. Tunnel excavation will disturb the surrounding soil, and displacement and deformation occur there. Since the pipe stiffness is 1000 to3000 times of the soil stiffness, pipe will restraint ground movement. The load applied and constraints existing on pipeline will change, and then internal forces within pipeline structures are subjected to change and redistribute. Therefore, the safety of pipelines adjacent to the tunnel will alter. So it is necessary to establish a model to judge the safety of pipeline.In this paper, by employing the principle of Winkler assumption, we consider the pipeline as a beam on elastic foundation, and analyze the interaction between pipeline and soil. The relationship between the deformation of pipelines, parallel and vertical to the tunnel, and the maximum ground settlement is studied. The corresponding computation formulae are also given. According to the control criterion of rigid pipelines and flexible pipelines; we judge the safety of pipeline with allowable deformation of the ground settlement. Since the corresponding parameters are random variables, a reliability analysis of the safety is developed in this paper. At last, some practical examples are introduced to demonstrate the applicability of mis method.This paper improves the traditional judgment and establishes the relationship between the reliability index and the allowable maximum ground settlement. So we can reckon a reliability index according the practical construction condition and the importance of different pipelines, and judge the safety of pipeline with the corresponding allowable ground settlement.