桩网结构路基格栅加筋作用及其拉力特性研究

为了研究柱网结构路基中土工格栅的加筋作用以及路基在动静荷载下土工格栅拉力的变化特性，建立了高速铁路柱网结构路基足尺物理模型试验装置，用激振器对路基施加动静荷载，利用土压力盒以及布拉格光栅分别监测路基内部土压力以及格栅拉力的变化特征.试验结果分析表明:路基上部荷载对路基内部土拱的稳定性存在影响，随着荷载的增大，土拱出现先强化后弱化的现象；桩土荷载分担比存在上限值，随着桩土差异沉降先增大后减小；当路基上部受到静荷载作用时，土工格栅能够使得桩顶上方承担的静荷载增加约12%，且路基中心处的格栅拉力增长最大；路基在长期动荷载作用下，格栅拉力产生了明显的变化，桩帽中心处的格栅拉力约增长了8%，路基筋材的设计需要考虑路基上方动荷载的影响. 

Reinforcing Mechanism and Tension Behaviors of Geogrid in Pile-Supported Reinforced Embankment

In order to study the reinforcing mechanism and tension behaviors of the geogrid in pile-supported reinforced embankment under dynamic and static loads, a full-scale model test setup for high-speed railway pile-supported reinforced embankment was built. Eight actors were used to impose loads on the embankment to simulate static loads and trains moving loads on the embankment. Meanwhile, stress cells and fiber Bragg grating (FBG) sensors were used to measure the soil pressure and tensile force of the geogrid. The experiment results show that the loads on the embankment could affect the stability of the soil arching. The soil arching experiences a process from strengthening to weakening during the increment of static loads. There exists an upper limit for the percent of loads undertaken by the pile cap. The geogrid could transfer about 12% static loads to the pile cap and the biggest tensile force of geogrid occurs at the center of embankment when the embankment is subjected to static loads. The tensile force of geogrid changes evidently; for example, the tensile force of the geogrid on the center of pile cap increases about 8% when the embankment is subjected to long-term train moving loads. Hence the design of embankment reinforcement should take the influence of moving loads into account.