路基填挖交界处路面裂缝的三维有限元分析

为了合理铺设土工格栅,防止路基填挖交界处路面开裂,分别建立不加格栅和加入不同层数、不同长度格栅的路基有限元计算模型,分析了路面顶面的竖向位移和沿路线纵向水平应力应变以及格栅的应力应变。格栅的布设减小了路面顶面竖向位移,分散了集中在填挖交界处的拉应力和拉应变,各模型中格栅的最大拉应力均小于1 MPa,最大拉应变均小于0.3%,布设一层时的格栅或多层布设时的底层格栅,拉应力和拉应变从路堑一侧到路堤一侧逐渐减小,其余层格栅的拉应力和拉应变,以靠近交界处路堑一侧最大。对计算结果的分析表明,土工格栅消除或延缓了路面横向裂缝的发生,布设一层时的格栅或多层布设时的底层格栅,路堑一侧应长于路堤一侧,其余层宜以交界处为轴对称布设。

3-D FEM analysis of pavement crack at cut to fill location of subgrade

In order to prevent pavement cracking at cut to fill location of subgrade,the treatment mechanism and proper layout of geogrid were studied by 3-D finite element method(FEM),subgrade FEM models with various lengths of geogrid and various number of geogrid layers were built,a model without geogrid was also built for comparison,the vertical displacement,longitudinal stain and stress of pavement surface and geogrid stain and stress were analyzed.Geogrid in subgrade reduces the vertical displacement of pavement surface,scatters the concentrated tensile strain and stress at cut to fill location.The maximum geogrid stress and strain of all models are below 1 MPa and 0.3% respectively.For one layer case and the bottom geogrid for multilayer cases,geogrid stress and strain are decreased gradually from cut to fill side.In the other layers,geogrid stress and strain at cut side near cut to fill location are maximum.It is discovered that geogrid eliminate or postpone the pavement transverse cracking,for one layer case,geogrid should be longer in cut side than in the fill side,the bottom geogrid should be longer in cut side than in fill side,and the others should be laid symmetrically for multilayer cases.4 tabs,12 figs,8 refs.