盾构隧道管片接头破坏特征及损伤特性试验研究

破坏特征和损伤特性是管片接头失效分析和承载性能研究的重要内容,对于确保其受力安全具有重要意义.文章开展了正负弯矩下管片接头抗弯破坏试验,对接头混凝土裂纹和压溃、螺栓受力和变形及接头位移等宏观破坏特征进行了总结,采用声发射技术对接头混凝土损伤演化过程和分布范围等细观损伤特性进行定量分析.研究结果表明:高轴压下管片接头破坏...

Experimental study on failure behaviors and damage characteristics of #br#segmental joints of shield tunnels

The failure phenomenon and damage characteristics are research focuses of failure analysis and load-carrying performance of segmental joints, which is of great significance to ensure the force safety of the joints. In this work, the compression-bending failure tests of segmental joint under positive and negative bending actions were carried out, and the macroscopic failure behaviors such as concrete cracks, collapse, bolt stress and deformation, and joint displacement were analyzed. The acoustic emission technique was adopted to quantitatively analyze the microscopic damage characteristics such as damage evolution process and damage distribution of joint concrete. The results show that: the failure of segmental joints under high axial compression are characterized by four main cracks, micro-cracks and crushed zone in the joint surface followed by crushed concrete in the compression zone. The bending dominated bolt deformation mode can be seen, and the bolt deformation under negative bending is more obvious. A significant peak in the acoustic emission count and energy during the failure process of joint can be observed, which corresponds to the joint failure phenomenon that the micro cracks on the joint surface develop to visible cracks, indicating that the load-carrying state of joint changes significantly. The damage range of joint along the direction vertical to the joint surface is 0.855h (h as the joint thickness) in positive bending side and 0.584h in negative bending side, respectively. The damage range of joint along the direction of segment width is 0.2b (b as the average segment width occupied by a single bolt equal to the segment width divided by the number of bolts) on either side of the bolt.