Experimental Study On Pile-soil Load Sharing Of Rigid Pile Composite Foundation Under Different Side Load Conditions

In the design of rigid pile composite foundation,the deformation calculation is an important content.When designing a composite foundation,its displacement calculation is a key element The project “Research on the calculation method of rigid pile composite foundation deformation” proposed a new idea of calculating the deformation of the rigid pile composite foundation by the stress superposition method.This method needs to determine when the load reaches Pile-soil load sharing when the characteristic value of bearing capacity of composite foundation.The research on pile-soil load sharing under the condition of buried depth(side load)is not sufficient.Therefore,the purpose of this study is to determine the pilesoil load sharing law of the rigid pile composite foundation under different burial depths(side loads)and the coefficient of single pile bearing capacity when the load reaches the characteristic value of the bearing capacity of the composite foundation.The research content of this paper is mainly divided into two parts: model test and engineering example calculation comparison.Model test:The scheme design,implementation and result analysis of the comprehensive test,combined with the previous model test results,put forward the concept of pile-soil load sharing of the rigid pile composite foundation considering the influence of buried depth.Starting from this,the measured data of the following model tests are analyzed and summarized respectively: loads borne by piles and soil in rigid pile composite foundation,the foundation soil,and the free single pile under different side load conditions is compared;The bearing properties of free single pile and foundation soil were compared;the axial force and lateral resistance distribution of the pile foundation of the composite foundation were analyzed;the deformation behavior of the deep soil between the piles of the composite foundation under different side loading conditions was compared;The relationship between the average reaction force of the soil and the load level;finally,by comparing,summarizing and summarizing the model test results and the previous model test data,a qualitative conclusion is given about the lateral load level and the coefficient of the single pile bearing capacity.1.The concept of load sharing of rigid pile composite foundation pile and soil considering the influence of the buried depth of the foundation is proposed.The side load can increase the carrying capacity of a rigid pile composite foundation,and the higher the side load,the greater the carrying capacity of the composite foundation.2.With the increase of the side load level,when the load level reaches the characteristic value of the bearing capacity of the composite foundation,the bearing factor of the bearing capacity of the composite foundation gradually decreases ?.3.Although the load sharing of the pile decreases when the characteristic value of the bearing capacity of the composite foundation is reached under the side load conditions,as the load level further increases,the pile load sharing increases faster,and the corresponding design should be considered in the design of the bearing capacity of the pile and the strength of the pile body.Safety reserve.Engineering example calculation comparison:The relevant results obtained from the test analysis were applied to the basic research project of the Institute,The calculation program of the project was used to calculate the deformation of the composite foundation using the stress superposition method for the model test and engineering examples with different burial depths.By comparison,the deformation calculation result of the stress superposition method is very close to the composite modulus method,which verifies the applicability of the stress superposition method for the calculation of composite foundation deformation,and also verifies the rationality of the model test conclusions.By adjusting different calculation parameters and working conditions(such as pile length,end resistance,lateral resistance,with or without depth correction,etc.)to calculate the engineering example,analyze and summarize the influence of different calculation parameters on the stress superposition method,the results show that the stress superposition method is close to the calculation result of the composite modulus method,but the caltulating theory of the stress superposition method is more reasonable.It is recommended to add more engineering examples to calculate and collect measured data,further analyze the relationship between the foundation depth and the bearing capacity of piles and soil,and verify the reliability of the deformation calculation by the stress superposition method.