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| 岩溶区高速公路桥梁下伏溶洞特征对其桩基承载力的影响 |
| Influence of Underlying Karst Cave Characteristics on the Bearing Capacity of Bridge Pile Foundations in Karst Highway Zones |
| 投稿时间：2025-01-10 修订日期：2025-04-23 |
| DOI： |
| 中文关键词: 数值模拟 溶洞埋深 跨径比 桩基承载性能 |
| 英文关键词:Numerical Simulation Karst Cave Burial Depth Span-to-Depth Ratio Bearing Performance of Pile Foundations |
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| 中文摘要: |
| 为揭示岩溶区高速公路桥梁桩基下伏溶洞几何特征对其承载性能的影响机制，本文以湖南某实际工程为依托，文章采用FLAC3D数值模拟平台构建了多组桩基–溶洞耦合模型，系统地开展关于跨径比与埋深两个关键参数的敏感性数值模拟。模拟结果与实测数据对比验证表明，所建模型具有良好的精度与适用性。研究发现：溶洞埋深增加可有效增强桩端围岩约束作用，抑制桩底变形，进而提升桩基整体承载能力，但溶洞顶板的沉降幅度有所上升；而跨径比的增大则引发顶板与桩底位移的协同增长，塑性区由局部发展至贯通状态，结构稳定性下降，桩端承载效率削弱。将时间因素引入围岩应力应变响应分析，揭示了桩底应力与位移的“响应延迟、峰值增强”特征，反映出在大跨径与深埋组合条件下，溶洞顶板面临更高破坏风险。上述结论可为岩溶区桥梁桩基的优化布设、溶洞结构处治及顶板支护参数选取提供理论依据与工程参考。 |
| 英文摘要: |
| To investigate the influence mechanism of karst cave geometry on the bearing behavior of bridge pile foundations in karst highway zones, this study, based on a practical engineering case in Hunan Province, establishes a series of coupled pile–cavity numerical models using the FLAC3D simulation platform. A parametric sensitivity analysis was conducted focusing on two key variables: span-to-height ratio and burial depth. Comparative validation with field monitoring data confirms the high accuracy and applicability of the established models.
The results indicate that increasing the burial depth of the karst cavity significantly enhances the lateral confinement provided by the surrounding rock to the pile end, thereby restraining pile tip deformation and improving the overall bearing performance of the foundation system. However, this improvement is accompanied by a greater settlement magnitude of the cave roof. Conversely, an increase in the span-to-height ratio leads to a concurrent rise in both roof and pile base displacements. This is further associated with a transition of the plastic zone from localized development to a fully connected failure mode, reflecting a decline in structural stability and a reduction in pile-end load transfer efficiency.
By introducing temporal factors into the analysis of stress–strain responses in the surrounding rock, it is observed that both stress and displacement at the pile base exhibit characteristics of delayed response and intensified peak values. This highlights a higher potential failure risk of the cave roof under the combined effects of large span and deep burial. The findings offer theoretical guidance and practical reference for the optimal layout of pile foundations, karst cave treatment strategies, and support parameter selection in complex karst geological settings. |
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