Analytic Solutions to Increment of Ultimate Bearing Capacity of Soils Under Caps of Composite Pile Foundations

Based on the ultimate bearing capacity of soils under strip and circular foundations and the theoretical solution for the ultimate resistance to the soil sliding around a pile, the theoretical formula of the ultimate bearing capacity increment of soils strengthened by piles under the strip and circular caps of compsite pile foundations are deduced, and the relevant calculating charts are also given. The reasonableness of the formula is shown in some examples and cases. The applicable conditions of the formula is discussed briefly.