大跨度下基坑支护结构体系受力及变形分析

Stress and Deformation Analysis of a Large-span Support Structure System

以中国科学院临床研究医院为工程背景,采用排桩与斜支撑相结合的支护体系,运用ABAQUS有限元软件建立本构模型,重点分析医院基坑施工过程中桩顶水平位移与斜支撑轴力的变化规律,并改变其斜支撑间距,分析对其造成的影响。首先模拟得到桩顶水平位移与斜支撑轴力,发现桩顶水平位移与斜支撑轴力均随着基坑开挖深度的增大而增大,最大值均发生在基坑开挖深度10 m处,桩顶水平位移的最大值为24.13 mm,斜支撑轴力最大值为600.85 kN,均未超过预警值;再对比现场监测数据,发现两者变化规律基本一致,验证了数值分析的有效性;最后改变其斜支撑间距,分别设置为6、8、10 m,并与原斜支撑间距进行对比,通过分析,发现原工程方案斜支撑间距设置最为合理。

Based on the engineering background of Clinical Research Hospital of Chinese Academy of Sciences,a support system combining row piles and diagonal bracing is adopted,and the ABAQUS finite element software is used to establish the constitutive model.The change law of the horizontal displacement of the pile top and the axial force of the diagonal bracing during the construction of foundation pit in hospital is analyzed,and its diagonal bracing spacing is changed to analyze the impact on it.Firstly,the horizontal displacement of the pile top and the axial force of the inclined support are simulated,and it is found that both the horizontal displacement of the pile top and the axial force of the inclined support increase with the increase of the excavation depth of the foundation pit.The maximum value occurs at the depth of 10 m,and the maximum horizontal displacement of the pile top is 24.13 mm.The maximum axial force of the inclined support is 600.85 kN,both of which do not exceed the warning value;Compared with the on-site monitoring data,it is found that the variation patterns of the two are basically consistent,which verifies the effectiveness of the numerical analysis.Finally,the diagonal support spacing is changed to 6 m,8 m,and 10 m,respectively,and compared with the original diagonal support spacing.Through analysis,it is found that the original engineering plan has the most reasonable diagonal support spacing.