Experimental Research On Lateral Dynamic Response Characteristics And P-y Curves Of Pile-groups

Due to its unique advantages of high stability, durability and others, pile is widely usedin various fields of civil engineering. Currently, the research on vertical bearing capacity ofpile has a lot, while the research of horizontal bearing capacity of pile remains to beelucidated, especially the lateral dynamic interaction mechanism of liquefiedsoil-pile-groups-slab structures.The small-scale shaking table tests of single pile and pile-groups will be done in avariety of conditions in this paper, and the FBG test system is used in pile-groups test inliquefied soil for the first time. On this basis, a detailed analysis and treatment about the testdata is done, and draw the difference of time-history curves of acceleration anddisplacement of pile-groups; Then, it analyzes and studies the test results of single pile andpile-groups; At last, by post-processing test data, reaching the p-y hysteresis curve and themain trunk of pile-groups, and with the corresponding pile testing and API specificationmethods are comparative studied.Firstly, in the design of the small-scale shaking table test, a new type of FBG dataacquisition system is applied to ensure the accuracy of the test data. In addition, the test ofsingle pile and pile-groups in dry sand and liquefied soil with the sine-wave and seismicwave inputting is designed, and the lateral dynamic response tests are done. By settinganother non-contact laser displacement gauge, it further validates FBG measurementsystem in shaking table test the feasibility of applying.Secondly, it analyzes the pile lateral dynamic characteristics by comparing theacceleration, displacement and pore pressure ratio schedule in variety of conditions,through processing the test data. Analysis found: In the dry sand, the forms of accelerationand displacement of slabs are similar to the form of shaking table input, the amplificationeffect of slabs is not obvious; However the acceleration and displacement grow rapidly withsoil liquefied in liquefied soil, and the amplification effect is obvious in the liquefied soil.The dynamic response of single pile tests is significantly higher than it of pile-groups tests.Finally, the p-y hysteresis curve of pile foundation and its main trunks are analyzed indifferent conditions. The results show that: The p-y curves are approximately lineardevelopment in dry sand, their slope and reaction force of soil round the pile are greaterthan those in liquefied soil， and the weaken speed of lateral stiffness is slower than it inliquefied soil. The tilt of the main trunk in dry sand test are in good agreement with thespecification, the API specification is required for proper reduction method, whether it issingle pile or pile-groups in liquefied soil, the soil is not only a simple reduction reactionforce sometimes.