Study On Vertical Bearing Mechanism Of Bored Pile With Post-Grouting To Soil Around And Bottom

Bored pile is the most common basis form used in the bridges, ports and high-rise buildings foundation. Because of construction technology, traditional bored pile may have the problme of hole collapse、thick bottom sediment、mud pile skin、hole stress release and so on. Based on a great deal of practices, post-grouting technologies of bored piles is an advanced construction technique developed to slove these defects. Therefore, the research on the bearing mechanism of post-grouting bored piles has very important engineering significance and practical value.Based on the bearing mechanism and influencing factors of bored pile, considering the effects of grouting, through the full size pile load test and ABAQUS finite element simulation, this thesis analysised the effect of post-grouting technique on adverse factors such as mud pile skin and bottom sediment, and then, studied the improve mechanise of bored pile’s bearing capacity, reached the following conclusions.It’s difficult to avoid shortcomings of cleaning the hole and the thick mud pile skin, which make the pile damage by steep drop type. After grouting, the destruction form of pile become by the steep drop type into the slow variant, and the pile’s baring mechanism is improved significantly.Post-grouting to soil around pile sides improve the mechanical properties of the pile-soil interface, which makes the pile shaft resistance substatially increase. The load test shows that, in cohesive soil the pile side friction resistance load sharing is always large, and the force charactistic of pile foundation is "friction piles". So, conducting the pile side grouting to increase the pile shaft resistance play value is the most effective way to increase the pile bearing capacity.The base post-grouting makes the strengh of the pile-bottom soil improve and its’compressibility reduce, which increases the pile tip resistance and the pile-bottom load sharing ratio. The tip resistance play in advance, which can further improve the tip resistance’s contribution of pile’s vetical bearing capacity.Post-grouting technique reduces the role of plastic displacement of the pile-soil interface, increases the integrity of the pile and soil around, make pile displacement and load transfer to a greater range of soil, which significantly reduce the pile settlement and substantially increase the pile’s ultimate bearing capacity. The technology shows its’good technical and economic benefits.