Analysis of Sealing Performance of Shield Tail Brush Based on Compression and Grease Escape Test

In order to study the effect of the quality of shield tail brush on the working performance of shield tail sealing system, based on dynamic compression test and grease escape test, the influence mechanism of long-term extrusion, wear degree of shield tail brush and mortar penetration on sealing performance of shield tail brush are revealed. Firstly, the variation law of the adhesion force of shield tail brush under various influencing factors is discussed based on the dynamic compression test. Secondly, the grease escape volume of shield tail brush under different working conditions is obtained by grease escape test. Finally, taking the adhesion force as the medium, the factors affecting the quality of shield tail brush are connected with the volume of grease escape, and the sealing performance of shield tail brush is discussed. The results show that, long-term extrusion, wear degree of shield tail brush and mortar penetration ratio have significant effects on the elastic properties of shield tail brush, especially the mortar penetration ratio can cause the elastic property loss up to 90%. There is a critical pressure in the grease pressure, and the critical grease pressure with shield tail clearance of 50, 70, 90 mm is 0.4, 0.3, 0.2 MPa respectively. When grease pressure is lower than the critical pressure, the volume of grease escape is very small. When it exceeds the critical pressure, the volume of grease escape increases sharply. The grease pressure further increases by 0.1 MPa, the volume of grease escape increases by more than 4 times. Under the condition of average shield tail clearance (70 mm), the volume of grease escape exceeds the allowable upper limit when the wear of protective plate exceeds 1/2 and the mortar penetration ratio exceeds 10%.