Centrifuge Experiment Analysis Of Bearing Characteristics And Pile-Soil Interaction Of High Strength Pile

As the construction of large-scale and significant projects thrives nowadays, High-Strength-Pile Composite Foudation, Piling Foundation as well as Composite Piling Foundation become more and more widely used in the treatment of foundations. Researches on the interaction between pile and soil thus can not only enrich the theory about foundation treatment, but also bear important meaningfulness towards the optimized design of projects. Based on the technique of centrifuge experiments, this paper initiatively designed a set of loading devices and then applied them to the single-pile loading experiments respectively on different modeling piles equipped with loading mini-sensors at different sections, which were operated after the centrifuge ran steadily. According to the analysis on the influence that pile strength and strength variation of the soil under piles have on the laws of load transfer via pile shaft as well as the characteristics of pile-soil interaction, this paper finally reaches such conclusions:(1) When the load above pile is fixed, pile shaft force gradually decreases along the depth of pile. While the load above pile increases, the pile shaft force, lateral resistance of pile and the resistance below pile consequently also increase. Meanwhile, as the load above pile increases, the proportion of resistence below pile to the total load increases, and the proportion of lateral resistance of pile to total load however decreases.(2) When the ratio of modulus of soil below pile to that of soil aside pile Eb/Es augments, the ultimate bearing capacity of single pile as well as that of soil below pile both enlarge. And fundamentally, the lateral resistance of pile nearby its lower end becomes greater when the soil strength of substratum tends to be larger. Moreover, if pile length increases, the ultimate bearing capacity of single pile thereby will be improved.(3) While the load above pile increasing, the stress variation of soil around pile caused by the lateral resistance of pile gets greater. And under the influence of lateral resistance of pile, the stress variation of soil around pile declines along the radial direction of pile shaft. The influence that lateral resistance of pile has on the stress of soil around pile is well in accord with its distributing manner: at the section where the lateral resistance of pile is comparatively larger, the relevant stress variation of soil around pile thus is greater; and at the section where the lateral resistance of pile diminishes, the relevant stress variation of soil around pile declines.(4) The vertically distributing manner of stress variation of soil around pile is in shape of "S" along the pile shaft:at the upper body of pile, the stress variation of soil around pile is minus. While at the lower body of pile, it becomes plus. And its absolute value firstly decreases, then increases and finally decreases again till almost the lower end of pile. Such a distributing manner is well in accord with that of soil stress caused by the resistance below pile and the triangular-distributing lateral resistance of pile which are determined by Mindlin Formula.(5) As the pile shaft force augments, settlement of the soil around pile which is under control of the lateral resistance of pile consequently enlarges. The influence that lateral resistance of pile has on the settlement of soil around pile declines along the radial direction of pile. The circular scope within which the soil around pile can be remarkably impacted by the lateral resistance of pile is of a diameter that is 3.9 times as large as the pile diameter. Even within an enlarged circular scope whose diameter is 8.5 times as large as that of the pile, can the soil around pile still be influenced by the lateral resistance of pile.