C-T快速连接件纵缝应用于盾构输水隧道时,隧道中的内水压使接缝处轴力减小,进而影响接缝的抗弯性能,但轴力变化对快速连接件纵缝抗弯性能的影响研究还不充分。因此,开展较小轴力正弯矩下C-T快速连接件接缝足尺压弯试验,并将试验结果与既有相同接缝的较大轴力工况试验对比,总结不同轴力下C-T件纵缝压弯力学特性。结果表明: 1)较小轴力下,C-T件纵缝的受弯过程可以分为混凝土单独承弯阶段和混凝土连接件共同承弯阶段。单独承弯阶段弯矩首先呈线性增长,之后接缝抗弯刚度不断减小。当C-T件搭接时接缝抗弯刚度增大,之后连接件快速屈服,抗弯刚度不断降低直至连接件断裂接缝破坏。2)较小轴力下,影响接缝抗弯能力的主要因素为C-T件的搭接、屈服及断裂,需要提高C-T件的抗拉性能以防止其过早屈服;较大轴力下,外侧混凝土的搭接和压溃是影响接缝抗弯能力的主要因素点。在不同轴力下连接件周围均出现裂缝。
When the longitudinal
joints with C-T quick connectors are used in
shield water conveyance tunnels, the internal water pressure in the tunnel
decreases the axial force at the joints, which in turn affects the flexural
performance of the joints. However, the axial force effect on the flexural
performance of the joints with C-T quick connectors has
not been adequately investigated. Therefore, a full-scale
compression-bending experiment of C-T quick connector joints under a smaller axial force was carried out
in this study. The experiment results were compared with those of the larger
axial force experiment with the same joint, and the flexural characteristics of
the joint with CT connectors under different axial
forces were summarized. The results show that: (1) Under smaller axial force,
the flexural process of CT connectors joints can be
divided into concrete bending stage and concrete and connectors bending stage.
In the concrete bending stage, the moment firstly increases linearly, and then
the flexural stiffness of the joint decreases continuously. The flexural
stiffness of the joint increases when the C-T
connectors are lapped, after which the connectors yields rapidly and the
flexural stiffness decreases until the joint failure. (2) Under smaller axial
forces, the factors affecting the flexural capacity of the joints are lap,
yield, and fracture of the C-T connectors; the tensile
properties of C-T connectors need to be improved to
prevent premature yielding; while under larger axial forces, the lap and crush
of the outer concrete are the critical nodes in the flexural process of the
joints. Cracks were observed around the connectors under different axial
forces.