| Our country is located in the earthquake-prone zone, as the pile foundation has agood seismic performance, it has been widely used in bridge engineering construction,and there are lots of bridge pile foundation in liquefiable site. Seismic damageinvestigation and test results indicate that along with the pore water pressure of saturatedsands rising, the soil mechanics performance change under seismic action, while thesechanges will affect the seismic performance of bridge pile foundation. And these changeswill affect the bridge pile foundation seismic performance, however, at present ourcountry current specifications for bridge pile foundation in ground of liquefactionseismic problems only have some qualitative rules, study on the dynamic soil-pile groupinteraction problem is the basis to improve the seismic research, so study on the dynamicsoil-pile interaction in liquefiable site became the necessary work to improve the seismicresistance of pile foundation of bridge in ground of liquefaction. Therefore, this papercentering on the influence factor of dynamic soil-pile interaction of group pile foundationin liquefaction ground carry out the following works.First of all, summarize and reviewthe research status quo of soil-pile interaction at home and abroad, Secondly brieflyintroduced the finished shaking table test, and processed and analyzed the test results.Third according to the shaking table test data to build liquefied soil-pile interaction finiteelement numerical model, through comparison of the data to verify the model reliability,Finally through the transformation of some parameters,size of cap and pile rows, analysisthe change of effects on dynamic soil-pile interaction. The main understanding andresults abtained as follows:firstly, briefly introduced the finished shaking table test.The soil of the shaking tabletest is composed of two layered：clay layer and saturated sand layer,2×2reinforcedconcrete group-pile system is setted up on it. Basal inputs of different amplitude,different frequency sine wave excitation, recorded the site and the dynamic response ofpile foundation, analysis the test results. The test results show that the frequency ofsystem acceleration amplification coefficient effect than amplitude effect, pore pressurein the low frequency waves under pore pressure rise faster.Secondly, the third chapter discussed the numerical model of dynamic constitutive model, coupled equations of soil and water conservation, realization form of u-p controland commingling analysis theory, aimed directly at the shaking table test of liquefiablesite, established3D numerical model of dynamic soil-pile interaction. Through thecomparison between calculated value and experimental value, verified reliability of thenumerical model.Based on the established numerical model, aiming at basal input of0.05g1Hz sinewave carrying out numerical simulation, Study the factors of weight of superstructure,pile diameter, pile rows and the cap size (ma), pile rows and pile spacing (s a/m) on thepile-soil dynamic interaction effect. The numerical results show that the diameter of pilehas strong influence on the characteristics of group pile-soil dynamic interaction, whileweight of superstructure has relative small influence on pile-soil dynamic interaction,manumerical variation does not change the general trend of near field acceleration, onlychanges the amplitude, numerical reduce would amplificate amplificationcoefficient of near field acceleration, increase increase the peak soil reaction,andthe numerical change of has great effect on pore pressure.Through the analysis of factors change affecting acceleration, pore pressure and soilreaction etc., obtain several important understanding of pile-soil dynamic interaction, Inorder to improve the seismic resistance of pile foundation in liquefiable site bridgedesign to provide a reference. |
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