Indoor Model Test And Numerical Simulation Analysis Of Load Transfer Law Of Self-anchored Test Pile

At present,the most reliable test method is to use traditional test pile to determine the bearing capacity of pile,but for the pile with higher bearing capacity,the traditional test pile method will increase the difficulty and cost of the test.If the self bearing capacity of pile body is used to provide mutual force,the above problems will be solved.This method is called self-anchored test pile.If a pile is divided into upper and lower sections.When the tensile load is applied at the top of the upper pile,the upper pile will be used as the anchor pile to apply the same compressive load to the top of the lower pile.This test method is called the self-anchored test pile method,from which the load-displacement curves of the upper and lower piles can be drawn.Then,the compressive bearing capacity of a complete single pile can be determined by transforming the load-displacement curve of the self-anchored test pile into the load-displacement curve of the traditional test pile.The design of self-anchored test pile method is reasonable and the theory is feasible,but as a new type of pile test method,there are still many problems to be studied.Therefore,based on the self-anchored test pile as the research background,through the indoor model test of self-anchored test pile as the main means,and combined with the numerical simulation analysis,this paper studies the single pile load transfer of self-anchored test pile,the interaction between upper and lower piles,and the conversion of self-anchored test pile results.This paper first introduces the indoor model test conditions,test materials and test process,the load-displacement curve of single pile,axial force distribution curve of pile body,friction distribution curve of pile side and additional stress distribution curve of soil around pile under different conditions can be drawn.Through the analysis,the paper explores the mutual influence between the upper and lower pile of self-anchored test pile and the conversion method of self-anchored test pile results,and simulates the indoor model test by using FLAC3 D software.Finally,the indoor model test results are compared with the numerical simulation results to verify each other.(1)Based on the physical model test platform,the single pile models under different working conditions are established,and the load displacement curves,the transfer law of pile body,the distribution form of pile side friction and the stress variation law of the soil around the pile are obtained.The differences of load transfer of single pile under different working conditions are explored,and the reasons for the differences are analyzed.It is found that the choice of loading point and direction has a great influence on the load transfer law.(2)The interaction between upper and lower piles is analyzed by comparing the load displacement curve,axial load transfer curve and side friction distribution curve of upper and lower piles.The results indicated that the upper or lower piles will cast pulling force on the other pile through the soil when they are loaded.In terms of the load transfer behavior and load level,however,the influence of the pull action can be ignored.Moreover,additional stress in the soil surrounding the pile increases with load while decrease with distance.In conclusion,the influence of the interaction between the upper and lower piles section on the bearing capacity can be ignored when converting the bearing capacity of the self-anchored pile to the bearing capacity of the conventional static loading test pile.(4)By comparing the indoor model test results of self-anchored test pile and traditional static load test pile,and by comparing the equivalent load method,equivalent displacement method,simple conversion method and other conversion methods,the optimal conversion method is determined as simple conversion method,The load displacement curves of the upper and lower sections of the self-anchored test pile are transformed into the corresponding load displacement curves of the whole pile.The converted results are close to the measured ones.(5)The model parameters of the numerical simulation are based on the experimental data.The load transfer law of each test pile obtained by the numerical simulation is consistent with the experimental data.The indoor model test and numerical simulation results are more accurate.Keywords are terms used in a dissertation for indexing,reflecting core information of the dissertation.An abstract may contain a maximum of 5 key words,with semi-colons used in between to separate one another.