Research On The Influence Of High Pressure Rotary Jet Pile Construction On Existing Pile

With the acceleration of the urbanization process in China in recent years,the urban area of major and medium-sized cities in our country is also increasing rapidly,and the municipal roads as urban blood vessels are also developing along with urbanization.The eastern coastal areas are economically developed,urbanization is fast,and the transportation system is very developed.Therefore,in the coastal urban road projects,foundation reinforcement technology should be used to improve the engineering geological conditions of the soil layer.High-pressure rotary jet pile is a foundation treatment technology developed in recent years.It has the characteristics of good reinforcement effect,wide application range,high controllability of pile diameter and low construction noise.Therefore,it has been widely used in the treatment of urban road soft foundation.However,the construction of high-pressure rotary jet grouting piles will squeeze the soil around the piles,which may adversely affect the existing structures and engineering pipelines around it.This problem has been seldom studied,so the research on this problem appears Very necessary.This paper first summarizes the research on the squeezing effect of the existing highpressure rotary jet grouting pile,and then based on the engineering case,the large-scale finite element software ABAQUS is used to numerically analyze the squeezing effect of the highpressure rotary jet grouting pile during the actual project.According to the engineering geological conditions Three typical sections were selected for research,and the changes of stress,displacement and bending moment of the bridge pile foundation under the action of high-pressure rotary jet piles were clarified;three construction methods were proposed,and the calculation results of the same section under the three construction methods were proposed After a comparative analysis,the best construction plan is finally given.Further analyze the related factors affecting the squeezing effect of high-pressure rotary jet pile The method of controlling variables was used to study the variation law of stress,displacement and bending moment of the existing pile foundation under the action of high-pressure rotary jetting pile under different silt layer thickness,silt layer position,pile length and pile type.When there is a thick silt layer nearby,the pile foundation with short length and simple structure is easy to produce displacement under the action of high-pressure rotary jet pile.Based on the pile forming mechanism of the high-pressure rotary jet grouting pile,the numerical simulation method of the high-pressure rotary jet grouting pile squeezing effect is improved,and the upper limit method of the high-pressure rotary grouting pile squeezing effect calculation method is proposed and verified by engineering cases;The drop model and the theory of round hole expansion give the calculation method of high-pressure rotary jet pile based on soil damage and verify it.