Analysis Of The Settlement Of The Improved Operating Expressway Using High Pressure Jet-Grouting Pile

Due to the increase of traffic flow and vehicle load,the post-construction diversity settlement of soft foundation expressway are more and more prominent,thus,settlement controlling of soft foundation for existing expressway is recognized to be of particular importance.High pressure jet grouting technique is one of the effective methods on soft foundation treatment.However,its application on existing expressway soft foundation treatment is relatively rare Based on the Jiangsu Yanhai expressway soft foundation project,Based on elastic-perfectly plastic analytic solution for cylindrical cavity expansion considering the rate-dependent effect and strength degradation of clay.A new method to calculate the diameter of the high pressure jet grouting pile was proposed.According to the finite analysis by ABAQUS.The improved finite analysis model using high pressure jet-grouting pile under static or dynamic load were set up.The factors,which contain diversity load,the parameter of pile and the distribution of pile,are selected for investigating the influence of these factors on the improvement.The main research work and achievements are as follows:(1)The method of the diameter of the high pressure jet grouting pile is verified by test data.According to the parameter analysis,the result shows that the larger stiffness coefficient will cause the larger diameter of plastic zone,in addition,when the cavity expansion ratio is same,the larger rate dependent effect will cause the smaller diameter of plastic zone,when the diameter of cavity expansion is same,the bigger strength degradation coefficients?95 will cause smaller diameter of plastic zone;when the velocity of cavity expansion is same the large cavity expansion ratio will cause the larger diameter of plastic zone.At the same time,the diameter of the high pressure jet grouting pile are more influence by the stiffness coefficient and rate dependent coefficient than the strength degradation coefficients?95 and the velocity of cavity expansion.(2)the static model shows that the large length and the elastic modulus of pile will cause the smaller settlement of the improved operating expressway,meanwhile,the greater diameter of pile and the smaller pile spacing,the bigger ratio of the area replacement,which will cause the smaller settlement of the improved operating expressway.(3)Under dynamic traffic load,the improved by pile model shows that the subgrade settlement will decreased 10 times than without improved.Analyzing the amount of lane load show the bigger lane load will cause greater subgrade settlement under traffic load.Meanwhile,the factors,which contain the diameter of pile and pile spacing,were selected of investigating the influence of these factors on the improvement.The results show that the bigger diameter of pile or the smaller pile spacing will cause smaller subgrade settlement under traffic load.So some advices were proposed to improved design by pile,it's wise that pile were near the wheel load and the distributed of pile use the bigger diameter and the smaller spacing of high pressure jet grouting pile.