The Study On Problems Caused By Design Mistakes On Sinking Pipe Cast-in-Place Piles

Buildings' unacceptable settlement often occurs due to inappropriate consideration about the effect of soil layers on sinking pipe cast-in-place piles, which even causes cracks. To reinforce them therefore is an important topic for us. In this thesis such a practice is introduced and many problems are discussed, by analyzing a project of this sort.After inspection and computation of a one-story-factory structure with cracks according to the Code GBJ78-9 and GBJ94-94, it is found that main cause is negative friction effect which consequently causes deficient bearing capacity and differential settlement of piles.In this thesis many reinforcing approaches are discussed. With the view of technique, construction, duration and economics, statically pressed anchoring bar piles is selected. Particularly, calculating of negative fiction, which is significant in soft soil, is discussed specifically.Since this reinforcement procedure has been finished, velocity of the settlement is stable and not beyond the rule's limitation.The main conclusions of this thesis are summed up as follows:1. Effect of the negative friction on piles takes even 20% amount of piles bearing losses.2. For a constructed building, because soft soil has been loaded by foundation for a long time, soils' properties had changed indeed which has to be emphasized in this paper. Designer should be concerned about it, otherwise reinforcing approaches will be too conservative.3. One of he best options of reinforcing approaches to soft soils and foundation is statically pressed anchoring bar piles.