Shuichi YAZAWA

Study on Reduction of Grease Flow Resistance by Element Tests

Mitsutaka SUGIMOTO

Recently, shield tunnels have been constructed in deeper underground with sharp curve, as underground structures in urban area become congested. Furthermore, segments become thinner and wider for saving its cost. Consequently, stress in segment during construction tends to be increased and then segment damage during construction is increased.
One of the predominant components of construction loads is tail force. In previous studies, to make clear the flow resistance characteristics of grease, which is filled up in-between wire brushes, and the frictional characteristics between grease and steel segment quantitatively, the element tests on grease and wire brush were carried out. As a result, it was found that high grease flow resistance appears in small tail clearance and big volume change of grease.
In this study, to reduce high grease flow resistance, the release valve is developed. To make clear the reduction of grease flow resistance characteristics by the release valve and grasp the appropriate interval between the release valves, the experiments were conducted with a test equipment. The obtained results are as follows.
1) All grease extruded was discharged from the release valve.
2) The release valve can make the grease pressure less than one third.
3) The more loading rate and the less number of the release valve make the maximum grease pressure increase.
4) The effect of pressure reduction by the release valve and the influence of the release valve size become apparent, when grease emissions per one release valve is high
5) The maximum grease pressure has a linear relationship with the grease this charging flow per one release valve. The relationship was formalized.