川西南公路顺层边坡桩锚组合结构加固分析——以乐西高速ZK9+352 ~ ZK9+526边坡为例

四川盆地周边地形地质条件复杂，公路建设中顺层边坡的工程病害频现。通过工程地质分析和数值计算，基于滑面损伤本构模型，研究顺层边坡支护前后滑面应力、位移和边坡稳定性系数等特征量的变化规律，验证桩锚组合结构加固顺层边坡的适用性；通过施工全周期现场监测，获取边坡深部位移、抗滑桩桩身弯矩和锚索应力的时效特征。结果表明：开挖扰动下顺层边坡具渐进性失稳破坏特征；自坡脚沿滑面向后缘，位移呈指数型平滑递减，剪应力先增大后降低，滑面损伤变量自剪应力峰值位置开始同频衰减；采用桩锚组合结构加固顺层边坡后，滑面位移最大值降低88.62%，最大损伤变量降低84.75%，稳定系数提高25.20%；坡体深部位移、抗滑桩桩身弯矩、锚索应力等监测验证了桩锚组合结构加固的有效作用。

Reinforcement Analysis of Pile-anchor Composite Structure in Bedding Slope of an Expressway in Southwest Sichuan: Taking Leshan-Xichang Highway ZK9+352 ~ ZK9+526 as an Example

The terrain and geological conditions around Sichuan Basin are complex, and the engineering diseases of bedding slope in highway construction are frequent. Through engineering geological analysis and numerical calculation, based on the damage constitutive model of the sliding surface, the variation law of the characteristic quantities such as the stress, displacement, and slope stability coefficient of the sliding surface before and after the bedding slope support were studied, and the applicability of the pile-anchor composite structure to reinforce the bedding slope was verified. Then, through the on-site monitoring of the whole construction period, the time-effect characteristics of the deep displacement of the slope, the bending moment of the anti-slide pile and the stress of the anchor cable were obtained. The results show that the bedding slope has progressive failure characteristics under excavation disturbance. From the slope toe along the sliding surface to the trailing edge, the displacement decreases exponentially and smoothly, the shear stress increases first and then decreases, and the damage variable of the sliding surface begins to attenuate at the same frequency from the peak position of the shear stress. After the pile-anchor composite structure is used to reinforce the bedding slope, the maximum displacement of the sliding surface is reduced by 88.62 %, the maximum damage variable is reduced by 84.75 %, and the stability coefficient is increased by 25.20 %. The monitoring of deep displacement of slope, bending moment of anti-slide pile and anchor cable stress verifies the effective effect of pile-anchor composite structure reinforcement.