Abstract: To determine the deformation safety limit of pipe joint of existing pipejacking tunnel disturbed by adjacent construction, the most commonlyused largediameter Fshaped pipejacking tunnel in pipejacking construction is analyzed. Based on several engineering cases, the failure types of water stop of pipejacking joint are presented, the geometric relation between the opening angle of the pipejacking joint and the detailed size is investigated, and the displacement control index is determined according to the existing specifications. The allowable tension angle and relative displacement (vertical displacement at both ends of pipe joints) corresponding to the waterstop failure of pipejacking joint are obtained by engineering calculations of typical pipejacking tunnel, then the deformation safety limit of largediameter Fshaped pipejacking tunnel at service stage is obtained. The following are the results: (1) The allowable opening angle of the pipejacking tunnel joint decreases with an increase in pipe diameter, and the minimum value is 0.84° and (2) The relative displacement has no obvious decreasing trend at a fixed pipe length, and the minimum value is 15 mm.

Key words: socket type pipe jacking, largediameter pipejacking tunnel, water stop failure, displacement model, deformation limit