桩承式加筋路堤受力机理及沉降分析

作为一种经济、有效的软土地基处理方法,桩承式加筋路堤在国内外已开始使用。把单桩处理区域及上部路堤等效为圆桩体,采用弹塑性有限元法分析了瞬时加载后地基中超静孔隙水压力的分布特征及消散过程,研究了加筋格栅的受力和路堤的沉降特性等,分析了桩长、桩间距及桩托板大小对桩体荷载分担比和路堤沉降的影响。研究结果表明,打桩后桩体所受荷载向下传递,地基中的初始最大孔隙水压力出现在桩端以下土层。打穿软土层情况下,路堤的沉降量决定于浅部桩间土的压缩,而未打穿情况下,路堤的沉降量决定于桩端以下软土层的压缩。桩长是控制路堤沉降的最主要因素,其次是桩间距和桩托板尺寸。最后对一个工程实例进行了分析。

MECHANISM AND SETTLEMENT ANALYSIS OF PILE-SUPPORTED AND GEOGRID-REINFORCED EMBANKMENTS

As an effective and economical treatment for soft soil,pile-supported and geogrid-reinforced embankment has been used widely in the world.In the numerical analysis,subsoil and embankment treated by one pile are simplified as a circular column;distribution characteristics and dissipation process of the initial excess pore water pressure under instantaneous loading are analyzed using elastoplastic FEM considering consolidation process of the subsoil.Mechanical properties of geogrid and settlement of embankment are also studied.The influences of pile length,pile space and pile cap dimension on load sharing ratio of pile and embankment settlement are also investigated.It can be seen that the initial maximum pore water pressure takes place in the lower soil due to the load transformation from pile cap to soil.When the pile penetrates the soft soil,the settlement of embankment is dependent on the compression of upper soil between the piles.Otherwise,embankment settlement lies on the compression of soil beneath pile.Pile length is the main factor that effects the settlement of embankment;pile space and dimension of pile cap are followed.A case study is performed at last.