Pre-overcutting outside shield machines is required to remove the NOMST wall at the extra cross-section in case of existing the extra outer part of shields such as outer pipes for inserting mortar into the excavated void. New methods were developed to cut the NOMST wall certainly by rotating type cutting equipments. Two equipments were made, one is the vertical type, the other is the horizontal type. Experiments were conducted to investigate the performance of these cutting equipments. By conducting the experiments, we verified that the two equipments could cut the NOMST wall at a short time and discharge the muck fairly well. Furthermore, we found out the optimum operating conditions and knew some informations as to operating the equipments in the real shield job.
