One cross section in the reinforcement segment by CFG piles of Wu-Guang high-speed railway was chosen to fix 14 flexible displacement meters at intervals in the geogrid on the pile top and in the soil between piles to monitor the change of the geogrid as the horizontal reinforcement with load and time. Combined with the monitoring results, the internal mechanism of geogrid deformation was studied. The results indicate that, either on the pile top or in the soil between piles, the geogrid deformation along the cross section of the subgrade can be approximately divided into three areas: the central area of subgrade, the transition area under the shoulder and the slope toe area of subgrade. The soil arching effect is the important factor in geogrid deformation process. Local compression area exists either on the pile top or in the soil between piles under soil arching effect. When the reinforced cushion is composed of graded crushed stones, the most easily failure place of geogrid is located at pile-soil juncture, and the failure mode of geogrid is more similar to acetabuliform rather than parabola.%在武广高速铁路CFG桩加固段选取一横断面,分别在桩顶和桩间土位置的土工格栅上间隔安装14个柔性位移计,测试土工格栅作为水平加筋体随荷载、时间的变化情况,结合测试结果,研究土工格栅变形的内在机理.研究结果表明,无论是在桩顶还是在桩间土的位置,土工格栅的变形沿路基横断面在路基中心区、路肩下过渡区和路基坡脚区表现出3种不同的变化规律；土拱效应是影响土工格栅变形的重要因素,受土拱效应的作用,在桩顶和桩间土中心位置均存在局部受压区域；垫层为级配碎石时,土工格栅最易受破坏的地方位于桩土交界处,土工格栅的破坏形态更近似平底锅形而非抛物线形.
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