桩承式加筋路堤格栅应变计算及试验

Calculation and test of geogrid strain in pile-supported reinforced embankment

为了完善桩承式加筋路堤中土工格栅应变的计算方法,在德国规范EBGEO的基础上,考虑桩帽及土工格栅刚度对格栅应变计算的影响,提出考虑等效桩径系数的修正计算方法,同时依托桩承式路堤现场试验,监测记录了路堤沉降、桩土压力和格栅应变的变化规律,并将实测结果与计算结果进行了对比。研究结果表明:格栅类型对路堤填筑期沉降影响不显著;桩土间的荷载传递随着格栅模量的增大而得到进一步加强;路堤荷载传递形式因采用不同类型的格栅而存在差异;填筑期内钢塑格栅应变随路堤填筑高度的增大而增加,且观测到了徐变性;钢丝格栅在填筑期内的应变变化不明显,但在填筑期结束后观测到了应变突变现象。通过现场试验与理论计算结果的对比,验证了采用等效桩径系数法计算格栅应变的合理性,并建议当采用钢丝格栅等高强刚度格栅时,可采用考虑等效桩径系数的修正EBGEO法进行格栅应变与应力计算。

In order to improve the calculation method of geogrid strain in pile-supported reinforced embankment,this paper based on the German standard EBGEO,considered the effect of cap and the stiffness of geogrid on the calculation of geogrid strain and proposed the modified calculation method with consideration of equivalent pile diameter.Based on field experiment of pilesupported embankment,the embankment settlement,pile-soil stress and rules of the geogridstrain variation were monitored and recorded,and the measured results were compared with the calculated results. The results show that types of geogrid have no significant effect on embankment settlement.Pile-soil load transformation is further strengthened with the increase of modulus of geogrid.There are differences in the transformation mode of the embankmen load.Strain of steel-plastic geogrid increases with the increase of the height of embankment in thefilling period,what’s more,creep is observed.The strain changes of wire geogrid during the filling period are not obvious,but strain mutation appears after that.By comparing the field experiment results with the theoretical results,the rationalization of the equivalent pile diameter coefficient method used to calculate the geogrid strain is verified.It is suggested that the modified EBGEO method with consideration of the equivalent pile diameter coefficient can be adopted for geogrid strain and stress analysis when the high-strength stiff geogrids such as steel geogrids are used.2tabs,9figs,20 refs.