桩网支承路基结构中土拱效应及网垫受力的模型试验研究

Model Study on Arch Effect and Bedding Force of Geosynthetics Reinforced and Pile Supported Embankment

基于相似理论,对桩网支承路基中心土拱效应进行8组模拟试验。测试桩顶轴力、桩土及路基不同高度处应力、格栅拉力和桩间土沉降随路基高度、外荷载变化特性,探讨格栅受力后变形。结果表明:加筋网垫上方竖向应力与以球形拱理论为基础的德国规范计算结果较为接近;加筋网垫下方桩间土承担竖向应力随路基高度、上覆荷载增加而增加;黏性土路基成拱效率略低于砂土路基;对于两层格栅组成的加筋网垫,下层格栅承担土拱效应竖向应力引起拉力大于上层格栅,位于桩帽之间并垂直于桩帽边格栅拉力大于平行于桩帽边格栅拉力;格栅初始松紧状态对土拱成拱效率有一定影响;格栅受力后平面变形形状近似呈悬索状。研究成果可为我国桩网支承路基结构加筋网垫相关规范提供参考。

On the basis of the theory of similarity,eight model experiments have been made to test the arch effect of the geosynthetics reinforced and pile supported embankment（GRPS）.The axial force of pile cap,stresses at different heights of the subgrade,tensile force of geosynthetics and inter-pile soil settlement and its variations with different heights of the subgrade and under different external loads have been measured in the course of filling and after filling.Deformations of geosynthetics have been studied.The results show as follows： Vertical stresses above the reinforced bedding are similar to the calculation results of the spherical shape arch method;vertical stresses below the reinforced bedding increase with upward-changing of the subgrade height and the superimposed load;arch forming efficiency of the clay filling material is a little lower than that of sand;for the reinforced bedding consisting of two layers geosynthetics,the tensile forces produced by the arch effect of the lower layer is greater than the upper layer;the tensile forces of the geosynthetics vertical to the pile cap is larger than those parallel to the cap;the initial status of geosynthetics influences the arch forming efficiency to some extent;plane deformations of the stressed geosynthetics are close to a suspension cable.Reference can be made to formulation of the Chinese GRPSE norms.