基于安全预警分级的基坑安全模糊评价研究

Study of fuzzy evaluation of foundation pit safety based on classification of safety early warning

在基坑施工过程中,基坑围护结构设计的稳定安全系数是不可测的,因此,《建筑基坑支护技术规程》(JGJ120-99)和《建筑基坑工程监测技术规范》(GB50497-2009)要求不同安全等级基坑的施工过程中有不同类型的监测项目,并给予相应的安全预警值。由于施工监测项目数据的不同步性,为避免对施工过程安全状态的"突发性"以及应对不同安全状态措施的需要,提出了安全预警分级方法。根据监测项目的实测数据,采用模糊数学方法定义了广义稳定系数评估施工过程的安全状态,并给出了广义稳定系数的安全下限。基于实际工程的监测数据,分析了不同监测项目广义稳定系数的变化过程,指出了安全控制的重点监测内容。

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.