Buckling safety factor of the design for supporting structure of foundation pit engineering is unmeasurable in the process of construction; so the different types of monitoring projects for the different safe states of foundation pit engineering are stipulated by the JGJ120-99

which is Technical Specification for Retaining and Protection of Building Foundation Excavations (in Chinese)

and the GB50497-2009

which is Technical Code for Monitoring of Building Foundation Pit Engineering (in Chinese). At same time

the safety alarming value is suggested respectively. Because of the asynchronism of monitoring data and with a view to avoid the burstiness of unsafe state of working progress of pit and demand for coping behavior of different safe states

the classifying method of safe state is suggested. In light of observed data of the different monitoring projects

the generalized stability factor is defined using the theory of fuzzy mathematics by which the destination is to estimate the safe state of work progress

and safe toplimit of the generalized stability factor is given. As a real example

the developing process of generalized stability factors for different monitoring projects are analyzed based on fuzzy calculation of observed data and the priority monitoring project of security control is pointed out.