深基坑钢筋混凝土支撑轴力监测值的非荷载影响因素

Non-load Influencing Factors of Force Monitoring Value of Reinforced Concrete Support Shaft in Deep Foundation Pit

支撑轴力是判断深基坑施工期间是否安全、围护结构设计是否合理的重要依据。在施工过程中,钢筋混凝土支撑轴力监测值通常大大超过设计值,而围护结构仍处于安全状态,使得施工监测失去指导意义。为保证基坑施工安全,使支撑轴力监测值处于有效控制状态,结合某工程实例,系统分析了各种非荷载因素。研究表明:1)初始值宜在混凝土浇筑后28 d后土方开挖前采集;2)监测数据应选在每日同一时段环境温度相近时采集;3)可通过局部设置钢支撑方式,校核分析钢筋混凝土支撑轴力监测值。支撑轴力应结合其他项目监测数据综合分析确定,使其精准,以保证施工安全。

During construction, the axial force and deformation of support are the important basis to judge whether the deep foundation pit is safe or not, and whether the design of the retaining structure is reasonable or not. The monitoring datum of support axial force always exceeds the design value in the process of construction while the retaining structure is still in a safe state, which makes no sense to do the construction monitoring. To ensure the safety of the foundation pit and make it in an effective control state, a variety of non-load factors ar9 systematically analyzed which combined with an project case, deducing that： 1） The initial value should be collected before excavation but after 28 clays of concrete curing; 2） The monitoring datum should be collected at the same time when the ambient temperature is close; 3） The monitoring value of support axial force can be checked and verified by the partial steel support which instead of the corresponding reinforced concrete support; Whether the foundation pit support structure is safe or not should be analyzed and determined in accordance with the monitoring datum of other projects.