Development Of A New Geotechnical Dynamic Triaxial Test Instrument

Earthwork building and its foundation sometimes will be affected by dynamic loading except by static loading, such as vibration load caused by earthquake, vehicles, machinery and explosion. For researching and evaluating of stability and deformation for earthwork building and its foundation under the dynamic loading, interrelated soil dynamic characteristics need be analyzed and grasped, such as the deformation and strength characteristics. Dynamic triaxial test is one of the main approaches for researching the soil dynamic characteristics indoor, and geotechnical dynamic triaxial test instruments are specially used for dynamic triaxial test, so the development of those instruments is critical for the research of soil dynamic characteristics. Although geotechnical dynamic triaxial test instruments have been developed more than50years in our country, but which still have a large gap with the well-known foreign companies’products, so R&D of geotechnical dynamic triaxial test instruments with independent intellectual property rights has become an important work of geotechnical test instruments’R&D in China.In view of the questions of domestic and overseas dynamic triaxial instrument, such as lowly loading precision of dynamic load caused by bidirectional exciting coupling, sample disturbance caused by contact measurement, development of a higher accuracy and more easily precise measurement dynamic triaxial has great ignificance. The new type of geotechnical dynamic triaxial test instruments in this paper use the the existing dynamic triaxial instruments of other countries for reference, the researcher input the whole surface digital image measurement system and bidirectional exciting control technology with proprietary intellectual property rights to improve the instrument’s performance to the advanced level both at home and abroad. The selection of the accumulator group and constant pressure variable pump in hydraulic servo loading system makes sure the pressure fluctuation is small when the dynamic loading and the oil source system’s energy saving when the static loading. Relying on the whole surface digital image measurement technology, non-contact measurement is realized and which can record the changes in position of the sample calibration points on the surface, and calculate the volumetric strain of the sample by back-office software; during the test, the camera will shoot change process of the sample uninterruptedly, which has great significance for the study of soil dynamic characteristics. The new geotechnical dynamic triaxial test instrument have some other characteristics, such as bidirectional exciting precise control, small load’s precise measure, aiding lifting device and so on. Combined with the dynamic triaxial test instrument and the functional requirements of the instrument, the author completed all the mechanical design, such as the dynamic triaxial test instrument’s pressure chamber, servo loading system, test operation platform and so on. input the whole surface digital image measurement system, installed and debugged the test instrument, analysed the test date.