环面不平整条件下衬砌管片抗剪承载力的试验研究

Experimental Study on Shear Bearing Capacity of Tunnel Segmental Lining with Uneven Ring Surface

以福州地铁6号线工程为背景,以P2型标准块管片为试验对象,通过设置不同垫片脱空高度来模拟后端环面不平整程度,开展衬砌管片抗剪承载力的原型试验研究。试验结果表明:后端环面不平整(垫片局部脱空)是导致管片开裂的重要原因。脱空高度较小时,千斤顶推力使脱空快速闭合,管片内通常不会产生裂缝;随着脱空高度增加,管片局部(中螺栓与脱空侧螺栓之间的内弧面区域)出现较大拉应力区并开始萌生纵向裂缝。脱空高度6 mm和10 mm时,初始开裂的顶推力分别为1000 kN和600 kN;随着千斤顶推力增大,裂缝继续向前端环面与内弧面中部发展,其延展方向与最大主应变方向大致垂直。

Taking Fuzhou subway No.6 project as the background and P2-type standard segment as the object,the prototype test research on the shear bearing capacity of segmental lining was carried out by setting different gasket void heights to simulate the uneven degree of rear end ring surface.The test results show that the main reason for the segment cracking is that the rear ring surface is not smooth(the gasket is partially void).When the void height is small,the jacking force makes the void close quickly,and there is usually no crack in the segment.With the increase of the void height,a large tensile stress area appears in the local part of the segment(the inner arc area between the middle bolt and the bolt on the void side),and longitudinal cracks begin to sprout.When the void height is 6 mm and 10 mm,the jacking force of the initial crack is 1000 kN and 600 kN respectively.With the increase of jacking force,the crack continues to develop in the middle of the front end annular surface and inner arc surface,and its extension direction is approximately perpendicular to the direction of the maximum principal strain.