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首先对应力路径的概念进行丰富和扩展,提出考虑主应力轴旋转的三维应力路径,然后采用数值方法,对基坑开挖过程中的应力路径进行了深入分析,研究了基坑内外各种应力路径及其规律,结果表明:开挖过程中无论横向还是竖向,应力路径都表现出卸荷特性,且坑内卸荷量大于坑外卸荷量,使得坑内应力变化及主应力轴旋转较坑外大;随着离基坑中心距离的增大,坑内应力变化减小,主应力轴旋转趋缓;开挖过程对坑外应力变化及主应力轴旋转的影响随离围护墙距离的增大而减小。坑内应力路径总体表现为平均压应力p减小,广义剪应力q减小,主应力轴偏转角增大;坑外应力路径总体表现为p减小,q增大,增大。最后归纳出基坑开挖过程中坑内与坑外的典型应力路径,以指导基坑工程实践设计分析和室内试验模拟。
Firstly, the concept of stress path is enriched and expanded. The three-dimensional stress path considering the rotation of the principal stress axis is proposed. Then the numerical method is used to analyze the stress path in the process of excavation. The results show that the stress paths exhibit unloading characteristics both in horizontal and vertical directions during excavation, and the unloading amount in pits is larger than unloading amount outside the pit, so that the stress changes in the pit and the rotation of the principal stress axis compare with the pit With the increase of the distance from the pit center, the change of stress in the pit decreases and the rotation of the principal stress axis slows down. The influence of the excavation process on the change of the stress outside the pit and the rotation of the principal stress axis increases with the distance from the retaining wall Big and small. The overall stress path in the pit shows the decrease of the average compressive stress p, the decrease of the generalized shear stress q and the increase of the deflection angle of the principal stress axis. The overall stress path outside the pit decreases as p increases and q increases and increases. Finally, the typical stress paths inside and outside the pit during the excavation of the foundation pit are summarized to guide the practical engineering design and laboratory simulation of the foundation pit.