Maki@TAKISE ANALYSES ON INFLUENCE OF CUSHION RING ON PIPE BY PROTOTYPE TEST OF PIPE JOINT Mitsutaka SUGIMOTO Development of technology on long distance jacking and jacking at sharp curve is expected recently, in pipe jacking method. To solve these problems, it is necessary to carry out the theoretical approach to jacking mechanism taking account of the whole of pipes and TBM, since all of the pipes are advanced with the TBM in case of pipe jacking method. Furthermore, acting load on pipe should be studied, based on the above approach. Therefore, the stack pipe model which can express theoretically the thrust mechanism has been developed, taking the interaction between foundation and pipes into consideration for the whole pipe system. To make clear the influence of cushion ring on pipe during jacking validate the developed model, the prototype test on pipe joint was carried out. Based on the above test, this paper reports the pipe joint behavior and the generating axial strain in the pipes due to jacking along straight and curved alignments. Furthermore, the test results were simulated by the developed model. As a result, it were found that the stack pipe model can simulate the pipe joint behavior and the strain in pipes due to jacking reasonably well.