Elastic-Plastic Theoretical And Finite Element Analysis Of The Compaction Pile Stress

As the fast development of architectural industry, the foundation quality has been called more and more higher. There are much limp foundation in our country, it distributing widely. So how to improve the foundation bearing capability and reduce the sedimentation becomes important problem of foundation treatment. The foundation treated by compaction pile is one of the normal soil improvement methods in loess area, especially in collapsible loess ones. It belongs to the vertical enhanced composite foundation, this method with the characteristic of good treating effectiveness, economy, and easy technique. Presently, studies on the foundation treated by compaction pile most concentrates on the improvement of construction technology and election of pile material, or soil parameter variation from compaction to end. There is few theoretical analysis and study about the soil stress variation and the soil compacted effect between piles when making holes. Mohr-Coulomb strength theory and Drucker-Prager yield criterion is always used as soil yield criterion. They have not considered the intermediate stress effect or the distinguishing of tensile and compression meridian, so they can not reflect the soil actual stress state.This paper studies the soil stress between compaction piles based on the Unified Strength Theory. Obtains the unified expression of elastic-plastic limit load. Considers the effect of parameters towards the development of plastic zone, then makes comparison with other results in order to illustrate that the analysis of soil stress between compaction piles based on the Unified Strength Theory is more agree with the actual soil stress and the result is reasonable. Then makes three-dimensional finite element simulating about the hole making of compaction pile based on the finite element analysis software-ANSYS 8.0. The finite element method considers about the soil's stress-strain nature and avoids some artificial assumption. Through calculation gets the limit load in every case that compared with the theoretical ones. The main conclusions are: 1. Leads-in the Unified Strength Theory, introduces its mechanical model, expression and its development and application. Mohr-Coulomb strength theory often been used as the soil yield criterion in soil plastic mechanics. This paper...