中文摘要：

长板-短桩组合型复合地基是由长塑料排水板与短水泥土搅拌桩组成的新型复合地基,该工法不仅利用短桩提高浅部地基承载力,而且通过长塑料排水板加快深部饱和软土的排水固结过程.针对长板-短桩工法处理上海A15I级公路深厚软基的固结特性,开展了现场试验研究,通过试验段不同位置和深度的超孔隙水压力、沉降变形以及桩土压力等参数随时间变化的观测与分析总结发现：排水板的存在,可以有效提高深厚软粘土的固结速率;长板-短桩组合型复合地基通过排水固结快速地提高桩间土强度,发挥桩间土承载作用;长板-短桩工法利用施工期的预压完成了80%以上的固结沉降,从而实现减小工后沉降的目的.

英文摘要：

Short cement-soil piles and long plastic drainage plates are used to form a new composite foundation,which is called as D-M method.It not only improves the bearing capacity of the upper soft soil through the short soil-cement piles,but also accelerates the consolidation process of the deep soft soil through the action of long plastic drainage plates.Field tests were carried out to research the consolidation characteristic of this composite foundation at A15 high way in Shanghai,and the test results such as the pore water pressure curves,settlement curves and pile-soil stress ratio curves were analyzed and some conclusions were drawn.The rate of the consolidation of the deep soft clay is greatly accelerated due to the drainage of the prefabricated vertical drain.The D-M method improves the bearing capacity of the soft soil;and more than 80% consolidation settlement is finished during the construction period,which effectively reduces the residual settlement.