Distributed Optical Fiber Inspection Technology For Foundation Piles And The Analysis Of Pile-Soil Interaction

The stability of pile foundation is the key to ensure the overall structural safety of large construction projects.The study of the interaction mechanism of pile and soil is helpful to clarify the bearing mechanism and the law of load settlement of pile,providing important evidences for the design of engineering piles and the safety assessment of pile foundation.The internal force distribution and deformation of the pile could be obtained by appropriate internal force detection methods,and a suitable load transfer model could be established by further analyses of the law of pile-soil interaction.Compared to traditional internal inspection methods,the distributed optical fiber detection technology has many advantages,which has been proved as an effective method by a large number of engineering applications.As we all know,many nonlinear load transfer laws of pile-soil are summarized by theoretical research results of pile-soil interaction domestically and abroad.Based on the distributed optical fiber measurement data,a new hyperbolic model(DHHM)is used to fit the load transfer function,and the pile of the test pile is simulated numerically by ABAQUS accurately.The main work and results of the paper could be summarized as follows:(1)The load transfer laws of pile-soil system was summarized by different theoretical research methods,and several typical load transfer models are introduced,and a hyperbolic load transfer model(DHHM)which could describe the characteristics of soil's elastic-plastic shearing deformation accurately is introduced.(2)The advantages and disadvantages of traditional pile internal force inspection technology were summarized,and several distributed optical fiber detection techniques(BOTDR,BOFDA and ROTDR)were introduced.The working principle of distributed optical fiber inspection technology was introduced emphatically,and the optical fiber site layout method of the multi cage concrete pile was introduced by an example.(3)The problems and processing methods of the measured data of optical fiber were discussed deeply.The operation method of the distributed optical fiber detection data processing system(DPDS)was introduced in detail,and the distribution of axial force and side friction resistance of the pile was analyzed based on the measured data of a test pile.(4)An accurate fitting algorithm(R2>0.98)for multi-parameters nonlinear model was proposed by Matlab algorithms,the parameters of the DHHM model of each soil layer were determined,and a new constitutive model of the contact surface between the pile and soil was obtained.(5)The DHHM model was embedded in the finite element analysis system by FRIC subprogram in ABAQUS,and the finite element modeling analysis of a site test pile was carried out.The simulation results and the calculated values were similar to the distributed optical fiber detection data.The finite element simulation of the custom load transfer model in ABAQUS was realized,and the accuracy of the constitutive model was verified;...