基于压缩和油脂逃逸试验的盾尾刷密封性分析

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

为研究盾尾刷质量问题对盾尾刷密封系统工作性能的影响,基于动态压缩试验与油脂逃逸试验,探讨了盾尾刷长期挤压、磨损程度、砂浆渗入对盾尾刷密封性能的影响机理.首先,通过动态压缩试验,获得各个影响因素下盾尾刷贴合力变化规律;其次,利用油脂逃逸试验获取不同工况下盾尾刷的油脂逃逸量;最后,以贴合力为媒介,将影响盾尾刷质量的因素与油脂逃逸量联系起来,探讨盾尾刷的密封性能.研究结果表明:长期挤压、盾尾刷磨损程度、砂浆渗入等因素对盾尾刷弹性性能的影响显著,尤其是砂浆渗入,盾尾刷弹性性能损失最大可达90%;油脂压力存在一临界压力,盾尾间隙为50、70、90 mm的临界油脂压力分别为0.4、0.3、0.2 MPa,低于临界压力时油脂逃逸量极少,超过临界压力时油脂逃逸量陡增,油脂压力增加0.1 MPa,油脂逃逸量增加4倍以上;在盾构平均盾尾间隙(70 mm)条件下,当保护板磨损超过1/2与砂浆渗入比超过10%时,油脂逃逸将超过工程容许上限.

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%.