Development of combined loading apparatus for centrifuge test

This paper presents the design, mechanism and performance of a combined loading apparatus that has been jointly developed at The Tokyo Institute of Technology and the Railway Technical Research Institute of Japan for centrifuge tests. The unique feature of the test system developed is that any combination of load and displacement path of combined vertical (V), horizontal (H) and moment (M) load can be generated and directly applied to model footing. The combined load, displacement and rotation can be accurately achieved by a feedback system that controls three loading jacks and three servo motors. The Cambridge-high performance contact stress transducer was customarily designed and placed into the system in order to evaluate the loads acting on the model footings. A set of LVDTs is also positioned to measure the movement of footings. The primary aim of the development of this system was to observe the footing behavior in V-H-M load and displacement space. The apparatus was first used to evaluate the performance and effectiveness of the new composite structure of shallow foundation and sheet pile called “sheet pile foundation”. The test results confirmed the expected performance of the newly developed loading apparatus.