桶形基础下沉的条件分析

从桶形基础下沉时的基本方程入手，讨论了影响基础下沉的条件．保证基础下沉可通过增大插入力或减小阻力实现，增加基础重力可增大插入力，但仅靠重力有时并不能达到预定插深．使用负压可同时增大插入力和减小阻力，插入力是由作用在顶板上的桶内外压差产生的，其大小与顶板有效承压面积及压差有关．为产生负压，首先应保证在自重插深时桶与土壤之间有足够的密封，理论最大负压与工作水深有关，但实际可利用的最大负压受排水泵能力、土壤性质及结构强度等因素的限制．使用喷冲和电渗也可以减小下沉阻力．工程应用可将上述各种方法组合使用．

Analysis on Penetration of Bucket Foundation

Suction effect is emphasized according to the basic equations of equilibrium and some practical cases. To ensure the penetration of bucket foundation, increasing penetration force or decreasing penetration resistance is adopted. Adding foundation weight can increase the penetrate force, how ever , the weight only is not enough to reach the aimed penetration depth sometimes. Suction can not only increase the penetration force, but also reduce the penetration resistance. Theoretically, the maximum suction is dependent on water depth, but it is restricted by pump, soil property and structure strength in fact. The penetration resistance includes skirt tip resistance and skirt friction resistance, which is reduced through seepage of water in the soil induced by suction. Other methods such as jetting and electroosmosis are also available. The combining methods are used in practice.