Experimental Study On Vertical Bearing Mechanism Of Bored Pile With Post-Grouting To Bottom

The bored pile,due to the advantage of its simple construction,the ability to provide a large pile capacity and less reinforcement,has been an extremely wide range of applications in the current foundation engineering.Traditional bored pile,however,owing to the impact of the construction process,there exists a hole collapse,thick pile tip sediment,pile side mud cake,pile stress release and other issues.These caused a significant reduction in the tip resistance and pile side resistance.Pile post-grouting technology can effectively eliminate the adverse impact of the bottom sediment,and the lower section of pile side mud cake.It is an effective increase the bored pile bearing properties,saving the cost of the project advanced construction technology.In recent years,many domestic and foreign scholars and engineers put a large number of on-site and laboratory test work on bored piles post-grouting technology and invent many types of grouting process and device.However,due to the complexity of the grouting method,pile piling process and geotechnical properties,many problems,such as post-grouting construction technology and bearing mechanism for specific soil,have not yet been satisfactorily resolved.This article is based on the pile foundation project of Zhengzhou City tricyclic fast engineering,which adopts field static load and indoor test method,mainly studies from the following aspects:(1)Combining with the actual situation of Zhengzhou that the soil is mostly silt and silty clay,I study the construction process of large diameter bored pile and the construction method of post-grouting.(2)Through on-site static load test,I comparatively analysis the Q-s curve and s-lgt curve of post-grouting piles and not grouting pile,and analysis the axial force curve,pile side resistance curve and the pile tip,lateral load sharing ratio situation,I also study the effection of grouting pile tip resistance and pile side resistance.(3)I take the pile end soil and do indoor tests.By the test results,I comparatively analysis the soil characteristic indicators which include unconfined compressive strength,cohesion and internal friction angle between post-grouting pile and not grouting pile.(4)According to the results of this research,I make recommendations for future research work.