Study On Soft Foundation Treatment And Post-Construction Settlement Prediction Of Highway Cement Mixing Pile

In the current expressway construction,some soft soil areas which the natural geological conditions do not meet the requirements are often passed along the road.In China’s hubei and hunan provinces,where the terrain is flat,rivers such as nets and lakes abound,there are a large number of fluvial soft soil areas,which make the construction of expressway face problems such as quality and engineering cost,among which the fluvial soft soil in wuxue area of hubei province is more obvious.Based on the construction of the north bank connection project of mayang expressway wuxue Yangtze river bridge,this paper studies the method of treating soft foundation by cement mixing pile and the law of post-construction settlement of pavement after treatment.The thesis mainly carries out the following work:(1)based on the geological exploration data of the project,the physical and mechanical index test data of the soft soil of the river and lake facies in the wuxue section were collected,and the engineering characteristics of the soft soil of the river and lake facies in the wuxue section were well reflected through statistical analysis,so as to provide reference for the study of the soft soil foundation in the multi-river and lake area.(2)taking K150+465 ~ K150+495 sections of cement mixing pile to treat soft soil foundation as an example,this paper studied the factors affecting pile strength,such as optimal cement mixing ratio,shaft speed of mixing pile machine,drilling machine and hoisting speed.The results show that the larger cement incorporation ratio and the larger stirring shaft speed can effectively increase the strength of cement mixing pile.(3)analyze the effect after the treatment of cement mixing pile test section,track and observe the settlement of sections K150+480,K150+576 and K150+671.The observation period is mainly after the treatment of cement mixing pile,the embankment filling and the completion of a period of time.By analyzing the settlement observation data of three sections with cement incorporation ratio of 15%,18% and 20%respectively,it is concluded that the higher the cement incorporation ratio is in the cement mixing pile under the same embankment load,the better the effect of controlling the settlement of foundation is,and the settlement is smaller in the same period after construction.(4)based on the settlement observation data of K156+875 sections,the measured data were compared with the prediction data of each prediction model.It is considered that the predicted results of hyperbolic method and star field method are closer to the actual settlement results and the error of exponential curve law is larger.