加筋形式对桩承式路堤工作性状影响的试验研究

对无加筋和采用不同加筋材料、加筋层数下桩承式路堤的工作性状进行了三维模型试验研究，侧重分析了桩土应力比、应力折减系数、填土中竖向应力分布、地基沉降等内容。结果表明加筋材料的设置有利于荷载向桩顶的转移，可有效减小沉降，但不同加筋形式下桩承式路堤的工作性状有所不同。使用单层或双层土工布时，路堤的荷载传递机理主要是填土的土拱效应和加筋材料的拉膜效应，但拉膜效应发挥相对较晚。使用双层格栅时，加筋材料与周围砂土形成半刚性平台。单层格栅的作用介于两者之间。试验结果与常规拉膜效应设计方法的对比表明，若假设荷载只由相邻桩间的加筋材料条带承担，计算的拉力将偏大，过于保守。

Experimental study on influence of reinforcing modes on behavior of piled embankment

In order to study the effect of the geosynthetic reinforcement on the behavior of the piled embankment, a series of three-dimensional model tests are carried out. In the tests, single and double layers of geotextiles or geogrids are used. The pile-soil stress ratio, stress reduction ratio, and vertical stress distribution in the embankment fill and differential settlement are compared with the data measured from the unreinforced embankment. It is found that the inclusion of geosynthetic reinforcements can enhance the efficiency of load transfer and reduce differential settlements, but the mechanisms of load transfer are different depending on the types and numbers of the geosynthetic reinforcement. When one or two layers of geotextiles are used, the load transfer from soil to piles is mainly caused by the combination of soil arching effect and tension membrane effect, and the latter acts later. In the case of piled embankment reinforced by two layers of geogrids, the mechanism of stiffened load transfer platform works due to the interaction of reinforcement and the surrounding fill. The piled embankment with a single layer of geogrid acts between the above two cases. Because only the geosynthetic strip between adjacent piles is assumed to be effective in the load transfer, the tensile force is overestimated in the conventional design methods.