双圆环形超深基坑支护结构的数值模拟与监测分析

结合某锚碇基础双圆环形超深基坑支护结构的工程实例,采用全三维有限元分析方法模拟整个基坑的施工开挖过程,考虑土和支护结构的相互作用,并结合现场的监测数据进行对比分析,得出了双圆环形超深基坑支护结构的变形特征和受力特性,以及周围土体的变形特征和塑性区分布.从结果看出双圆环形超深基坑具有明显的空间效应和拱效应特点,按照传统方法进行设计是偏于保守的;同时因双圆环形超深基坑支护结构本身变形较小,所以内衬由于地下连续墙位移而产生的内力并不占主导地位,而施工期间的温度变化等其他因素对其受力有很大影响,因而,内衬环向应力基本以受拉为主.

Numerical Simulation and Monitoring Analysis of Double ring Bracing System in Super Deep Foundation Pit

The deformation law and the mechanics characteristic of the double-ring bracing system in super deep foundation pit was studied through numerical simulation and monitoring analysis. Based on the example of double-ring bracing system in foundation pit for South Anchor of the Fourth Nanjing Yangtze River Bridge construction, the full three-dimensional finite element model was used to simulate the excavation of the whole foundation pit. Interaction between the bracing structure and the soil had also been taken into account in calculation. Compared with that of measurement, the results indicate that traditional design is conservative when applied in the design of double-ring bracing system in account of space effect and arching effect, and the stress of lining is affected mainly by temperature change during the construction rather than the deformation of concrete diaphragm wall due to the small deformation of bracing structure.