分级循环荷载下土工格室加筋路堤模型试验研究

目前对土工格室加筋路堤研究主要集中在静载条件下，动载条件下研究的比较少。为研究分级循环荷载下土工格室加筋路堤的力学性能，采用USTX-2000的动力加载装置进行加载，对土工格室加筋路堤在不同加筋层数、格室高度、格室焊距等工况下进行一系列模型试验。对分级循环荷载下路堤的竖向变形和坡面法向变形进行研究，并与固定振幅循环荷载及静载作用下的路堤进行对比分析，研究不同加载方案路堤力学性能的差异性。试验结果表明，土工格室加筋能显著提高路堤承受分级循环荷载的能力和减小竖向累积沉降量，在加筋间距一定的情况下，两层及以上加筋效果比单层加筋效果更显著，格室高度增大和格室焊距减小均可不同程度提高路堤承受分级循环荷载能力并减小竖向累积沉降量；加筋可减小路堤分级循环荷载下的坡面法向变形，格室高度增大和格室焊距减小在分级循环荷载幅值相同时均能减小坡顶和坡中处的法向累积变形；分级循环荷载作用下，当振次≥8 000或幅值≥80 kPa时，路堤竖向累积沉降量超过固定振幅循环荷载，当振次≥9 000或振幅≥90 kPa时，路堤坡顶法向累积变形超过固定振幅循环荷载；分级循环荷载作用下，路堤竖向和坡面法向累积变形均大于静载，加筋可有效减小分级循环荷载和静载作用下坡面法向累积变形差。

Model experimental study of embankment reinforced with geocells under stepped cyclic loading

Current research on geocell-reinforced embankments is mainly concerned with the static load condition, and little attention is paid to dynamic loading conditions. To investigate the mechanical property of geocell-reinforced embankment under stepped cyclic loading, a series of model tests is performed, using the loading device of USTX-2000, on geocell reinforced embankment with different reinforced layers, different heights of geocell and different welding distances. The vertical and normal deformations at the slope of embankment are monitored under stepped cyclic loading, and compared with those of the embankment under fixed amplitude cyclic loading and static loading, by which the difference of mechanical properties under different loading schemes are analyzed. It is shown that geocell can significantly increase the capacity of the embankment under stepped cyclic loading condition, and reduce the vertical cumulative settlement. At fixed reinforcement spacings, the reinforcement effect of two or more layers is more significant than that of single layer. Both the increase of the height and the decrease of the welding space of geocell can improve the capacity of the embankment under stepped cyclic loading conditions and reduce the vertical cumulative settlement. Reinforcement can reduce the normal deformation of slope of embankment under stepped cyclic loading. Both the increase of the height and the decrease of the weld space of geocell can reduce the normal accumulated deformation of the top and the middle of slope in the same amplitude of stepped cyclic loading. Under the effect of stepped cyclic loading, when the number of vibration is greater than or equal to 8 000 or the amplitude is greater than or equal to 80 kPa, the vertical cumulative settlement of embankment exceeds the fixed amplitude cyclic loading. When the number of vibration is greater than or equal to 9 000 or the amplitude is greater than or equal to 90 kPa, the normal accumulated deformation of the top of slope exceeds the fixed amplitude cyclic loading. Under stepped cyclic loading, both the vertical cumulative settlement of embankment and the normal accumulated deformation of slope are larger than those under static loading, and the reinforcement can effectively reduce the difference between stepped cyclic loading with static loading in the normal accumulated deformation of slope.