温度骤降对混凝土内支撑结构体系的变形影响分析及建议

Analysis and Suggestion on the Influence of Temperature Plunge on the Deformation of Concrete Internal Support Structure System

以广州某深大基坑为例,通过监测数据的详细分析,总结温度骤降对混凝土支撑体系的变形影响,重点得出基坑顶水平位移、深层位移的变化规律,并通过对本工程的处理措施的介绍和梳理,提出解决类似工程问题的工程建议。结果表明:温度骤降会导致杆件收缩,增大基坑顶水平位移,且位移变化具有一定的滞后性、持续性和恢复性;在设计、施工、监测过程中应注意温度的影响,设计过程中可通过增大构件尺寸、控制跨度、提高混凝土强度、增加构造配筋、做好变截面过渡和节点连接等措施控制温度效应的不利影响;施工过程中要控制浇筑、浇捣、养护质量,做好保温保、保湿措施、控制坑边荷载,如出现温度裂缝应及时封填处理;监测方面应选择稳定、合理的监测时段,如出现异常应及时报告,并加强监测,必要时,可由设计单位根据实际情况动态调整监测要求。

A deep foundation pit in Guangzhou as an example,through the detailed analysis of monitoring data,summarizes the impact of temperature drop on the deformation of concrete support system,focusing on the change law of the horizontal displacement of the founda‐tion pit top and the deep displacement,and through the introduction and sorting of the treatment measures of this project,puts forward engi‐neering suggestions to solve similar engineering problems.The results show that:the temperature drop will cause the shrinkage of the bar,increase the horizontal displacement of the foundation pit top,and the displacement change has a certain lag,continuity and recovery;in the design,construction,monitoring process should pay attention to the impact of temperature,the design process can be through increasing the size of the member,control span,improve the strength of concrete,increase the structure reinforcement,do a good job in the change of section transition and node connection measures to control the adverse effects of temperature effect;in the construction process to control the quality of pouring,pouring,curing,do a good job in the thermal protection,wet monitoring measures,control the load of the pit edge,such as the occurrence of temperature cracks should be timely sealing treatment;in terms of monitoring should choose a stable and reasonable monitoring period,such as abnormal should be reported in a timely manner,and strengthen the monitoring,if necessary,can be adjusted by the design unit according to the actual situation of dynamic monitoring requirements.