桩承式低填路堤土拱效应的数值模拟

Numerical simulation on soil arching effect of piled low embankment

利用数值模拟试验研究低填路堤下土拱效应的特性.通过建立三维土拱模型,研究影响土拱效应的主要参数——桩布置形式、桩间距、填土高度和扩大头直径间的相互关系.结果表明,无论是三角形还是正方形布置形式,钉形桩的应力分布具有显著的空间对称性;在布置形式、填土高度和桩间距等参数一定的条件下,随着钉形桩扩大头直径的增加,土拱效应发挥程度降低,当扩大头较大,相邻两桩桩边缘较近时,群桩的挤土作用较明显;在正方形桩体布置形式下,填土路堤中应力分布较均匀,挤土作用下的土拱形态对称性比三角形布置形态要好,但桩土应力比却并不一定比三角形的大.在设计中需要综合考虑填土高度、扩大头直径以及桩的布置形式等因素.

To study the characteristics of soil arching effect on piled low embankment, a three dimensional soil arch model is conducted to analyze the key parameters influencing soil arching. The results show that pile stress distribu-tion of T-shape column has the characteristics of significant spatial symmetry. For a given condition of pile configura-tion, soil filling depth and pile spacing, the soil arching effect becomes less moblized as the diameter of pile head of Nail-shape pile increases;whereas if the pile head diameter is large and the adjacent piles are close, the squeezing effect of pile group becomes more significant. Under the arrangement of the square piles, the distribution of stress in the embankment is uniform. The symmetry of soil arching form under soil compaction effect is better than the one of triangle layout, but the pile-soil stress ratio is not necessarily larger than that of the triangle layout. Therefore, it is necessary to comprehensively consider the filling height, the pile head diameter and layout form.