中文摘要：

围护结构的内力变形是基坑分析的主要内容，也是基坑工程安全控制的主要指标。目前基坑工程中对围护结构的监测侧重于位移测试，内力测试方法则不够准确。风险预警多以位移增量作控制指标，未能反映结构受力变形的真实状态。本文根据结构受弯时内力与变形的力学关系，提出了基于位移测试结果计算结构弯矩的方法——单元挠度法，并结合实例分析了单元长度的合理取值。结合基坑围护结构位移测试结果和由此计算得到的弯矩分析，考虑构件位移和内力两种控制参数，可对其风险状态进行综合判断。实例应用分析表明，所提出的围护结构综合风险判别方法计算简便，能动态得到即时弯矩和风险状态，并可弥补位移单参数风险预警的不足。

英文摘要：

Internal force and deformation of retaining structures is the main content of excavation analysis which is the main indicator of safety. The present monitoring focuses on retaining structures displacement. The stress test method is not accurate enough to reflect the actual internal force. According to the mechanical relationship between the internal force and bending deformation, a method to calculate structural moment based on the displacement test result named unit deflection method （UDM） is proposed, and the suitable value of the unit length is confirmed by an example. Combined with the displacement test results and calculated moments by UDM, the risk is judged by both displacement and internal force. A case analysis shows that the comprehensive risk criterion on lateral supporting structures is convenient in calculation, could get instant moment and risk status dynamically, and makes up the shortfall of one-parameter risk criterion.