超高无面板式土工格栅加筋路堤现场试验研究

Field tests on super-high geogrid-reinforced soil embankment without concrete panel

结合在建宜巴高速公路50 m高的加筋填土断面进行现场试验,对超高无面板式土工格栅加筋路堤的格栅变形、垂直土压力、水平土压力、分层沉降以及深层水平位移等内容进行了近2 a的测试,研究超高无面板式土工格栅加筋土路堤的受力、变形规律,分析了其作用机理。结果表明:不同层位土工格栅的最大拉应变出现在离返包面约4~6 m处,格栅应变沿筋长呈双峰值分布,施工期土工格栅应变具有明显的滞后性,且工后1.5 a格栅出现明显的收缩回弹;土工格栅的存在对土压力分布具有明显的调整作用,格栅末端附近实测垂直土压力值略超过理论值,中间和近坡面部位实测土压力值小于理论值;水平土压力沿路堤高度呈非线性形式分布,路堤中部的水平土压力值略大于顶部,其值小于主动土压力;分层沉降量在施工期存在较大波动,在垂直高度上,上部和底部偏小,中下部偏大;深层水平位移随着深度的增加逐渐减小,填土结束后深层水平位移仍有一定程度增大。

Field tests on a 50 m-high geogrid-reinforced soil embankment without concrete panel of Yichang-Badong Highway in Hubei Province are conducted.The tests include the measurements of tensile strain of geogrids,vertical earth pressure,horizontal earth pressure,layered settlement and deep horizontal displacement.The stress and deformation laws are revealed and the mechanism is analyzed.The results show that the maximum tensile strain of geogrids at different layers appears to be about 4-6 m away from the wrapped face,and the tensile strain along reinforcement has two peak values.The strain of geogrids has obvious lag in the construction period,it shrinks and rebounds after construction.The geogrids adjust the distribution of earth pressure.The measured value of the vertical earth pressure at the end of geogrids is slightly larger than the theoretical value,and it is less than the theoretical value in the middle and outside part of the slope.The horizontal earth pressure is nonlinear along the filled earth height.In the middle of the embankment,the horizontal earth pressure is larger than that at the top,and it is less than the active lateral earth pressure.There are a lot of volatilities in the layered settlement,and the value in the middle of the embankment is greater than that in other areas.The horizontal displacement decreases with depth,and it develops to a certain extent after construction.