Research On Load Transfer Mechanism Of DX Pile

DX pile is a three-pronged squeezed cast-in-situ pile.It is based on a rotary excavation pile and uses a special squeeze-expansion device to squeeze the soil at an appropriate position on the pile to form a cavity.The variable cross-section pile type of a bifurcation is based on the static load test report of a DX pile in a plot in Chenggong District of Kunming City.The load transfer method is used to study and analyze the bearing characteristics and load transfer characteristics of the DX pile.Three parts:1.The bearing characteristics and load transfer laws of DX piles are studied.The test pile is discrete into multiple pile segments.The load transfer method is used to establish the analysis model.The displacement coordination and force coordination between the pile segments are used as the calculation and control conditions.,Iteratively calculates and analyzes the entire test pile from the bottom of the pile,and at the same time,for the current geological survey report,the soil information parameters are incomplete,the types of moduli provided are few,and the conversion between moduli is uncertain and depends on The empirical formulas and correction coefficients are difficult to apply to the load transfer method.The parameter correction method and the uniform experiment method are introduced to improve.The bearing behavior and load transfer law of DX piles are discussed.The research shows that the optimized calculation method after introducing parameter correction and uniform experiment improvement can more accurately reflect the load characteristics of DX piles when pulling up,and can also solve the problem of incomplete soil layer information parameters in the geological survey report during calculation,and can also improve Accuracy of test pile analysis.2.The load correction method optimized by the parameter correction method and the uniform experiment method is used to calculate and analyze the on-site compressive DX test piles.The DX compressive test piles in this project have high bearing capacity and a small overall settlement,especially those that control the initial settlement.The ability is very outstanding.The settlement value does not exceed 1mm when the first-level load is 1400 k N,and the settlement does not exceed 4mm when the 1/2 limit load is 3500 k N.The reason for the calculation and analysis is that there is a large initial critical side friction resistance around the pile,which leads to the pile The amount of displacement required to produce a certain amount of lateral friction resistance on the side is small.On this basis,the applicability of the traditional hyperbolic model to the calculation of test piles with initial critical lateral friction resistance is discussed.The optimization method of load transfer parameters can fully reflect the difference of critical lateral friction resistance and load performance of different test piles,making the calculation results closer to the actual working conditions,and can more accurately reflect the load transfer mechanism of compressive DX piles.3.Based on the engineering pile static load test data,ten DX test piles that did not reach the design limit bearing capacity appeared,and the two methods of eccentric load and bearing plate failure of the DX pile were discussed using the numerical analysis method and the load transfer method.The causes of failure are briefly discussed.The two methods of judging the failure modes are discussed.The possible failure positions of DX piles under eccentric load and the development law of load-settlement curve after bearing plate failure are studied.Some related projects are also given.