Study On Geotechnical Dynamic Experimental Techniques For Electromagnetic Shaking Table

Earthquake simulation shaking table is a widely used tool of important physical simulation research under seismic loads in structure failure mechanism;equipment and instruments safety test;aseismic theory evaluation and catastrophe prevention key technologies.To explore and develop new earthquake simulation shaking equipment and related technology plays an important rule in improve our scientific and technical capabilities and economic development speed.Electro-hydraulic drive system is the most widely used means of shaking table excitation currently,however,electromagnetic drive system shows a great ability in wide band response,long vibration hold ability and high level of test safety,etc.,when compared with the former one.With an enormous potential value and practical significance in solving various kinds of high-frequency vibration forms and complicated load problems under the high speed development of civil engineering in China,it is the most important development direction of new generation shaking table.Therefore,the electromagnetic shaking table and related technology development has been earned more and more concern from domestic and foreign scholars.This paper,based on a new type of electromagnetic shaking table,developed by the Institute of Engineering Mechanics,China Earthquake Administration and the ANCO Engineer,Inc.,the USA,andobjective development need of soil dynamic patternmaking and test technical,conducted in-depth research on the electromagnetic shaking table design and performance evaluation methods,system Modules and testing techniques.The main tasks and achievements of this paper are:1.Mastered the shaking table history and research status;compared the advantages and disadvantages of different excitation forms;analyzed and summarized the current research and development level of soil dynamics test technology,based on the full investigation of existing test techniques,pointed out research direction.2.Described three-part composed structure named control system,drive system,load system respectively and a servo motor-rocker-rod joint driven features;gived data collection,model boxes,auxiliary testing and other aspects of the design elements and ability characteristic3.Utilized the acceleration sweep and function curves sweep test methods,mastered and evaluated the basic properties of electromagnetic shaking table;conducted plurality of input seismic waves screening test under nominal operating frequency range and overrun operating frequency range,selected El-centro seismic wave as the optimal input seismic wave of this shaking table.4.Designed and developed a new pluviation modelling device,analyzed the basic performance of this device by calibration tests method;evaluated the influence on the relative density by the key elements;given the proper use of pluviation modelling device and the reliability control parameters,the sample preparation apparatus controllable minimum steady relative density of the dry sand sample is 50% and 35% for saturated sample.5.Conducted a dry sand and saturated sand model parallel test model,analyzed accelerometer deflection phenomenon which are commonly seen in the shaking table simulation test;established a geometric correction method based on the position and orientation of the state,compared with several common correction filtering methods to verify the rationality and reliability of the method.Did research on the boundary effect low of model box and evaluated the model box boundary effect.