Squeezing Effect And Bearing Capacity Of PHC Pile In Expressway Extension Project At Soft Soil Area

With the development of our country’s economy, prestessed high strength concrete pipepile (PHC pipe pile) is widely used to highway construction in recent years. In general, PHCpile was just used in the emergence of engineering to save security or special part ofengineering because of its higher cost than other improving method of soft soil. As manyspecial advantages exist for PHC pile, made in manufactory displaying the whole produceprocess to customers, impossible to rest too much of pile body causing of installing machinefounction, all of people related to the construction of PHC pile hope it was to be done well. So,this type of pile was welcome and widely applied recently. Prestressed pipe program used inExpressway Extension Project of soft soil section is too expensive, which is usually solvedthrough increasing the pile spacing and improving the structure of cushion. The calculationmethod for extruding soil effect of driving in larger space and bearing capacity of PHC pileare issues that designer should consider. Rely on the Guangzhou-Qingyuan ExpresswayExtension Project, through field tests, many tests were conducted deeply for PHC pile ofextruding effect and bearing capacity of single pile.The extruding soil effect of PHC pile was researched based on field test. PHC piledriving process belongs to soil compaction pile-sinking mode. Excess pore water pressurecaused by pile-driving in the project presented approximately linearly with the depthincreasing and reduced with the distance increasing in the horizontal direction. Soil horizontaldisplacement of soil compaction effects decreasing as the distance increasing; it also has thesignificantly of hysteresis which can lead to pile body tilt. Piling on the widened foundationinfluences the original foundation slightly, while the site conditions have remarkableimpaction on Pile Driving effect.The old embankment restraints horizontal displacementperpendicular to the roadbed direction.The PHC pile of pile capacity characteristics was studied by Cone Penetration Test (CPT)and single pile bearing capacity test. The bearing capacity of single pile from calculatingbased on CPT indicators and the field bearing capacity test has higher consistent.The changeand distribution law of the stress and strain of the PHC pipe pile in the loading and unloadingprocess was founded by embedded optical fiber and steel bar meter in the pile.The stress andstrain of the pile with decreases as the depth increases; the mode of load distribution of PHCpile reflects that it has the attribute of friction piles.