包裹砂桩复合地基的承载力和沉降特性

Bearing Capacity and Settlement Characteristic of the Wrapped Sand Pile Composite Foundation

对包裹砂桩挤密复合地基与压密砂土地基进行静载荷对比试验,研究了桩长、桩径、桩间距和长径比的改变对包裹砂桩复合地基承载力与沉降的影响。试验结果表明:地基土中增加包裹砂桩可以有效限制地基土侧向变形,发挥包裹砂桩桩体的竖向承载力,使处理后的复合地基承载力明显提高,沉降显著减少;桩径、桩间距和长径比对包裹砂桩复合地基承载力和沉降影响较为显著,随桩径增大和桩间距减小,复合地基承载力提高且沉降降低,长径比明显变小时,桩土应力比更大,更有利于桩承载力的发挥,而桩长对其影响并不明显;包裹砂桩复合地基的桩间距不宜大于4D;桩侧土压力随深度递减,桩侧和桩端荷载分配比例与桩长关系不大。

Based on comparisons of the wrapped sand pile composite foundation with the crushed sand soil foundation,this paper analyzes the correlation control factors on the capacity and settlement of the wrapped sand pile composite foundation,which are the pile length,pile diameter,pile spacing and ratio length/diameter ratio(L/D).Test results show that the soil lateral deformation can be effectively limited to add wrapped sand pile into sand soil foundation,and the vertical bearing capacity of wrapped sand pile can be brought into full play.It can be seen that the bearing capacity of the composite foundation can be increased obviously but settlement of the foundation becomes smaller.The pile diameter,pile spacing and L/D have significant influence on the bearing capacity and settlement of wrapped sand pile composite foundation,with the increase of pile diameter and the decrease of pile spacing,the bearing capacity of the composite foundation is increased and the settlement is reduced,when L/D reduces obviously,pile-soil stress ratio is greater and it is more beneficial to the carrying capacity of pile,whereas the length of pile has no obvious influence on it.The pile spacing of wrapped sand pile composite foundation is not more than 4 times diameter of the pile.The earth pressure of pile side decreases with depth.The load distribution rate between pile-side and pile-end has little relation with pile length.