Data for Fig 11.

Influenced by the complex geological conditions in mountainous region, micro-pile foundation for transmission line faces the risk of insufficient bearing performance. It is important to study the risk suppression measures of micro-pile foundation and its assessment method to promote the construction of transmission lines in mountainous regions. Firstly, the mechanical simulation model of pile-soil system for the micro-pile foundation is established in this paper, and the field test is carried out to verify the accuracy of the simulation model, thus the ultimate load of the micro-pile foundation is determined according to the current code requirement for maximum displacement in case of damage to the group pile foundation. Secondly, to address the subjectivity of traditional methods, an improved Likelihood-Exposure-Consequence (LEC) method is proposed. Its novelty lies in constructing a quantitative displacement-risk mathematical mapping, directly linking the physical limit state (maximum displacement) to the risk likelihood factor. Thirdly, structural risk reduction measures for the micro-pile foundation using micro-expanded pile foundation and micro-inclined pile foundation are proposed, and the ultimate load of the traditional micro straight pile foundation is used as an excitation to carry out the simulation of the bearing performance of the two improved micro-pile foundations, and the maximum displacements of the two improved micro-pile foundations are calculated. Finally, based on the proposed improved LEC method, the risk values-defined in the LEC framework as the quantitative product of Likelihood (L), Exposure (E), and Consequence (C)-and risk classes of the two improved micro-pile foundations are calculated and compared with the conventional micro straight pile. The results demonstrate that the proposed strategies significantly reduce the safety risk class, providing a robust, quantifiable basis for optimizing foundation designs in complex mountainous terrain.

受山区复杂地质条件影响，输电线路微桩基础（micro-pile foundation）面临承载性能不足的风险。研究微桩基础的风险抑制措施及其评估方法，对推动山区输电线路建设具有重要意义。本文首先建立了微桩基础桩-土体系的力学仿真模型，并通过现场试验验证了该仿真模型的准确性，进而根据现行规范中关于群桩（group pile foundation）破坏时最大位移的要求，确定了微桩基础的极限荷载。其次，针对传统方法存在的主观性问题，本文提出了一种改进的似然-暴露-后果（Likelihood-Exposure-Consequence, LEC）方法，其创新点在于构建了定量的位移-风险数学映射关系，将物理极限状态（即最大位移）与风险似然因子直接关联。再者，本文提出了采用微扩桩基础（micro-expanded pile foundation）与微斜桩基础（micro-inclined pile foundation）的微桩基础结构降险措施，并以传统微直桩基础的极限荷载作为激励，开展两种改进型微桩基础的承载性能仿真模拟，计算得到二者的最大位移。最后，基于本文提出的改进LEC方法，计算得到两种改进型微桩基础的风险值——在LEC框架中，风险值被定义为似然性（Likelihood, L）、暴露性（Exposure, E）与后果性（Consequence, C）三者的定量乘积——及其风险等级，并与传统微直桩基础进行对比。结果表明，所提出的优化策略可显著降低安全风险等级，为复杂山区地形的基础设计优化提供了稳健且可量化的依据。