降雨条件下三级桥基岸坡-BFRP锚杆体系的协同变形机制研究

Coordinated deformation mechanism of three-tier bridge abutment slope-BFRP anchor system under rainfall conditions

为探讨降雨条件下三级桥基岸坡-玄武岩纤维增强复合材料(basalt fiber reinforced polymer,简称BFRP)杆体系的水文响应和协同变形机制,以实际工程案例为依托开展室内物理模型试验,测试得到了坡体含水率、土压力、锚杆轴力及应变响应数据。分析了边坡降雨-入渗-变形的阶段性演化规律及过程响应,提出了坡体“分级加固,兼顾整体与局部”原则的强度-渗流-变形综合防控措施。基于多属性响应数据系统,阐明了桥基岸坡-BFRP锚杆体系的协同变形机制。结果表明:降雨条件下桥基岸坡表现出由3级→2级→1级的变形演化趋势,1级边坡底部在积水软化、卸荷回弹和应力集中效应影响下更易发生累积性破坏。边坡张拉裂缝初步形成或扩展时,BFRP锚杆轴力呈受拉突增趋势,即边坡的阶段性变形特征与BFRP锚杆轴力的变化趋势较为吻合,该指标有望为降雨条件下边坡的变形监测提供可靠依据。BFRP锚杆的柔性加固性能可有效遏制降雨诱发的坡体变形,在此基础上应采取坡体排水和绿化护坡等措施对其进行补强加固。

To investigate the hydrological response and coordinated deformation mechanism of the three-tier bridge abutment slope reinforced with basalt fiber reinforced polymer(BFRP)anchor system under rainfall conditions,indoor physical model experiments were conducted based on actual engineering cases.The experiments collected data on slope moisture content,earth pressure,anchor axial force,and strain responses.The phased evolution patterns and response process of slope rainfall-infiltration-deformation were analyzed.A comprehensive control strategy for the strength,permeability,and deformation of the slope was proposed,following the principle of“graded reinforcement,balancing overall and local considerations”.By utilizing a multi-attribute response data system,the coordinated deformation mechanism of the bridge abutment slope-BFRP anchor system was elucidated.The results indicate that under rainfall conditions,the bridge abutment slope undergoes a deformation evolution trend from three-tier to two-tier and then to one-tier.The bottom of the first-bench slope is more susceptible to cumulative damage due to water softening,unloading rebound,and stress concentration effects.When tensile cracks initially formed or expanded in the slope,the axial force of the BFRP anchors exhibited a sudden increase trend,aligning the stage deformation characteristics of the slope with the axial force trend of BFRP anchors more effectively.This index is anticipated to offer a dependable foundation for monitoring slope deformation during rainfall.The flexible reinforcement capability of BFRP anchors can efficiently mitigate slope deformation caused by rainfall.Subsequently,actions like slope drainage and implementing green slope protection should be implemented to strengthen the slope.