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<p>In response to the challenges of controlling deformation in pile–anchor support systems during the rapid excavation of foundation pits in strongly weathered rock slopes, this study is based on the Huangshan’ao project in Yinzhou District, Ningbo, China. Through systematic field monitoring and comparison with theoretical predictions, the effectiveness of the prestressed anchor anti-slide pile support system in controlling slope deformation is demonstrated. The results show that during the rapid excavation phase, both horizontal and vertical displacement growth rates at the pit top were high, with maximum cumulative displacements reaching approximately 5.7 and 5.9&#xa0;mm, respectively. After the installation of prestressed anchors, the displacement growth rates at all monitoring points decreased from 0.27 ~ 0.33&#xa0;mm/d during rapid excavation to 0.01 ~ 0.02&#xa0;mm/d, representing a reduction of 93 ~ 95%; confirming the significant effect of active support in controlling slope deformation. Furthermore, the deformation of the anti-slide piles was mainly concentrated in the shallow layer (with a maximum displacement of about 3.86&#xa0;mm), while the deep-layer displacements were nearly zero, which verifies the rationality of the pile design. The peak axial force of the deep anchors reached 297.4 kN, which exceeded that of the shallow anchors by 23 ~ 48%, reflecting the dominant influence of deep soil thrust. Based on displacement prediction models established by the m-method and the p–y curve method and anchor load-transfer theory, the theoretical values of pile displacement and anchor axial force show a deviation of only 5 to 15% from the measured values. In addition, during the initial tensioning stage, the prestressed anchors rapidly developed axial force and then maintained values around 200 ~ 280 kN in the stabilization stage, in good agreement with the theoretical predictions (180 ~ 260 kN); thereby the load-transfer model was validated. This study fills the gap in field-monitored deformation data under rapid excavation conditions in strongly weathered rock slopes. It also evaluates the applicability of theoretical methods (m-method and p–y curve) for deformation prediction under such geological conditions.</p>

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Field Monitoring and Analysis of Rapid Excavation-Induced Deformation in a Supported Foundation Pit within Strongly Weathered Rock

  • 期刊论文

  • 发表日期：

    2025年9月3日

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  • Lijin Dong,
  • Huajun Wang,
  • Guangyi Ku,
  • Cuigui Qing,
  • Changguang Qi,
  • Wenjie Yao,
  • Zhenyu Wu

摘要

In response to the challenges of controlling deformation in pile–anchor support systems during the rapid excavation of foundation pits in strongly weathered rock slopes, this study is based on the Huangshan’ao project in Yinzhou District, Ningbo, China. Through systematic field monitoring and comparison with theoretical predictions, the effectiveness of the prestressed anchor anti-slide pile support system in controlling slope deformation is demonstrated. The results show that during the rapid excavation phase, both horizontal and vertical displacement growth rates at the pit top were high, with maximum cumulative displacements reaching approximately 5.7 and 5.9 mm, respectively. After the installation of prestressed anchors, the displacement growth rates at all monitoring points decreased from 0.27 ~ 0.33 mm/d during rapid excavation to 0.01 ~ 0.02 mm/d, representing a reduction of 93 ~ 95%; confirming the significant effect of active support in controlling slope deformation. Furthermore, the deformation of the anti-slide piles was mainly concentrated in the shallow layer (with a maximum displacement of about 3.86 mm), while the deep-layer displacements were nearly zero, which verifies the rationality of the pile design. The peak axial force of the deep anchors reached 297.4 kN, which exceeded that of the shallow anchors by 23 ~ 48%, reflecting the dominant influence of deep soil thrust. Based on displacement prediction models established by the m-method and the p–y curve method and anchor load-transfer theory, the theoretical values of pile displacement and anchor axial force show a deviation of only 5 to 15% from the measured values. In addition, during the initial tensioning stage, the prestressed anchors rapidly developed axial force and then maintained values around 200 ~ 280 kN in the stabilization stage, in good agreement with the theoretical predictions (180 ~ 260 kN); thereby the load-transfer model was validated. This study fills the gap in field-monitored deformation data under rapid excavation conditions in strongly weathered rock slopes. It also evaluates the applicability of theoretical methods (m-method and p–y curve) for deformation prediction under such geological conditions.