Model Test Study On Pile Foundation Of PHC Piles

PHC pipe piles have been widely used due to their various advantages,but most of the current researches are based on soft soil layers,the change of geological environment is not considered for the differences of bearing characteristics of PHC pipe piles,and the influence of group pile effect.Therefore,the theoretical study on the pile foundation of PHC piles in special geological environment has a strong practical significance.In this paper,the research status of PHC pipe piles at domestic and abroad is sorted out,and the problems remaining in the theoretical and practical research are summarized.Based on the project with pipe pile foundation applied in Paleo-clay area,designed the model test to study the difference of bearing performance of the pile by to changed the conditions such as pile spacing,pile number and cap form.The ANSYS software was used to supplement the analysis of the single pile group,the four pile group and the nine pile group test,and the calculated data were compared with the test.Concluded as follow:(1)The model test results show that the settlement deformation of the PHC pipe pile foundation is stable after loaded,the pile axial force increases proportionally to the applied load,and the pile side friction resistance curve shows "double peak type".(2)When studying the influence of pile distance variation,it is found that the settlement deformation of foundation is more stable when the pile distance is farer.The axial force value of the 6D pile distance is largest at the same load,the 3D pile distance is smallest,and the value of the pile side friction resistance is also increase with the pile distance is farer.The proportion of piles under the three pile distance conditions is also different,and is inversely proportional to the pile distance.The group effect coefficient increases in proportion to the pile distance,and the value is greater than 1.(3)When studying the influence of cap form variation,it is found that under the low cap form,the ultimate bearing capacity of foundation has been significantly improved,but the axial force of the single pile is smaller than that of the high cap form.At the same time,the frictional resistance in the range of 0?16.5cm on the pile side is smaller than that in the high cap form,and there is a phenomenon that the peak point moves downward.The stress of the soil under the slab is“M”type at the working load stage,and tends to " V " type distribution after reaching the ultimate load.(4)When studying the influence of pile number variation,it is found that the increase of pile number makes the foundation have better resistance to vertical deformation,and the settlement curve is more gradual.The ratio of load of each pile in nine pile foundations is different,showing the law of angle pile>side pile>center pile;and the accumulation of test load makes the proportion of the load of the center pile larger,and the angle pile,side pile begins to decrease.Figure 38 Table 5 References 65...