Engineering practices indicate that narrow braced excavation exhibits a clear size effect. However, the slip circle method in the design codes fails to consider the effect of excavation width on basal heave stability, causing waste for narrow excavation. In this paper, numerical simulation for basal heave failure of excavation with different widths was performed by FEM with SSRT (shear strength reduction technique). The results revealed that the failure mechanism of narrow excavation is different from the complete slip circle mode. In addition, the safety factor decreases increasingly slowly as the excavation widens and stabilizes when approaching the critical width. Subsequently, the corresponding computation model was presented, and an improved SCM (slip circle method) was further developed. Finally, the engineering case illustrated that it can effectively optimize the design, which exhibits clear superiority.

中文翻译：

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估计窄支撑开挖的基础升沉稳定性

工程实践表明，窄支撑开挖表现出明显的尺寸效应。但设计规范中的滑移圆法没有考虑开挖宽度对基隆稳定性的影响，造成窄基坑开挖浪费。在本文中，采用有限元法和 SSRT（抗剪强度降低技术）对不同宽度基坑的隆起破坏进行了数值模拟。结果表明，窄基坑开挖的破坏机制不同于完全滑移圈模式。此外，当接近临界宽度时，随着开挖变宽和稳定，安全系数下降越来越慢。随后，提出了相应的计算模型，并进一步开发了改进的 SCM（滑环法）。最后，