中文摘要：

通过cfg桩复合地基的大型室内模型试验,研究褥垫层厚度、桩长、桩间距对cfg桩复合地基沉降和桩土应力比的影响规律.结果表明:复合地基的cfg桩存在扩径现象,且从下至上扩径现象越明j显；褥垫层越薄,桩分担荷载越大,桩间土荷载分担比越小；随着褥垫层厚度的增加,桩承担荷载增长趋势变缓,故为充分发挥桩的承载作用,建议合理褥垫层的厚度为20～30 cm;在外荷载一定的情况下,桩土应力比随桩长和桩间距的增加而增加,因此在进行复合地基桩间距的设计时,不仅要保证复合地基承载力满足设计要求,而且还要保证加固后地基土的工后沉降量满足规范要求,同时还应充分考虑打桩带来的不利影响.

英文摘要：

The effects of cushion thickness, pile length and pile spacing on the settlement and pile-soil stress ratio were studied by large indoor model test of CFG pile composite foundation. The results show that, various degrees of expanding diameter exist in CFG pile composite foundation, and the diameter expanded decreases in order from top down. The smaller is the thickness of cushion, the bigger is the sharing load of piles and the smaller load sharing ratio of soil among piles. The growth trend of the load borne by piles becomes very slow along with the increase of the cushion thickness. So it is advised to set the reasonable thickness of cushion to 20~30 cm in order to give full play to the load bearing role of piles. Pile-soil stress ratio increases with the increase of pile length and pile spacing under the circumstance of constant external load. Accordingly, in the pile spacing design of composite foundation, not only the bearing capacity of composite foundation must be ensured to meet the design requirements, but also the post-construction settlement of foundation soil must be ensured to satisfy the code requirements. Meanwhile, the negative influence of piling should also be taken into full consideration.