The Study Of Centrifugal Modeling Test On Bearing Capacity Of Single Pile Under Horizontal Load

With the rapid development of economy, the rising up of high-rise buildings in the city and the rapidly increasing of bridges, ports and offshore drilling platform, the pile foundations is widely used. Pile foundation has high bearing capacity and small settlement. Since pile foundation can bear the vertical force, lateral force and bending moment at the same time, it can meet the harsh requirements on bearing capacity and settlement deformation in the civil engineering and ocean engineering. Many experts and scholars have made a lot of research on pile long time ago, but most of the research is aimed at the vertical ultimate bearing capacity of pile, and the research on the characteristics of horizontal bearing capacity of pile foundation study is smaller relatively. Many piles under vertical load bear horizontal load even to be main load in construction engineering and ocean engineering, so the research on the lateral bearing capacity behavior of pile foundation is of great significance. In this paper, the author does a series of comparative tests through the drum geotechnical centrifuge in Dalian University of Technology to study the characteristics of lateral bearing of pile foundation. Lots of research work carried out as follows:Specimen preparation is one of the most important steps in geotechnical model experiment, especially for sand. In order to obtain the sand sample of good uniformity and high repeatability, a set of automatic sanding equipment is developed. A series of tests are conducted to study the relative density on the influence of sand flow rate and drop height with Fujian standard sand. And the relative position tests and CPT penetration tests are carried out to check the validity of this new device. The results show that the relative density of the sample increases gradually with the increasing of drop height, while decreases with the increasing of the sand flow rate, and this device is able to prepare sand sample of relative density range0.47to0.94, with high uniformity and high repetition. This device is used to prepare sample for centrifuge model test.Through domestic first drum geotechnical centrifuge, a series of experiments are developed by changing the relative density of foundation soil and loading mode to study the mechanism of pile-soil interaction. The result show that:under unidirectional loading, pile horizontal load increases gradually with displacement; pile bending moment is controlled by the horizontal load and moment is linear with load; the maximum moment appears in the0.3of burying depth. Under cyclic loading, the displacement of pile and horizontal secant modulus increase with the cyclic number, and tends to be stable after some cycles. Under horizontal cyclic displacement, the pile horizontal load changes periodically with the displacement, developing into hysteresis loops; the maximum horizontal load and bending moment increase with the cycles. In all tests, horizontal load, pile bending moment, pile horizontal secant modulus and the horizontal displacement of pile are affected by the relative density of foundation soil.