Abstract A shield-driven tunnel is a longitudinal flexible structure prone to such issues as dislocation and axis deviation, which are contrary to the requirements for high precision in prefabricated construction. In view of this, the common practice is to correct and eliminate shield tunnel deformation-induced deviations by means of cast-inplace strips and leveling layers in conjunction with the synchronous construction process in shield tunnelling. In other words, it is to form a monolithic prefabricated and assembled structure of "prefabricated main body + small amount of cast-in-place component". However, the space inside the shield-driven tunnel is so limited that excessive cast-in-place strips and over-thick leveling layers are not economical or time-efficient, and would also take up valuable internal space. Therefore, the cast-in-place strips and leveling layers should be set up in a reasonable manner so that they meet the need to eliminate longitudinal uneven deformations in shield-driven tunnels without taking up too much space. In light of this, this paper analyzes the characteristics of longitudinal uneven deformations in shield-driven tunnels based on the measured axis deviations in Shanghai Zhuguang Road tunnel and extant relevant literatures, and combined with the construction process it proposes a reasonable solution to eliminate longitudinal uneven deformations in shield tunnels with prefabricated and assembled lane structures, as well as a reasonable value for the thickness of the leveling layer. The results show that as for the upper prefabricated lane structure, the cast-in-place concrete base with bonded rebars could eliminate most of longitudinal uneven deformations in shielddriven tunnels, while leveling layers could eliminate a small amount of longitudinal uneven deformations and assembly deviations. For the lower prefabricated lane structure, longitudinal uneven deformations and assembly deviations in the shield-driven tunnel could be eliminated with leveling layers. The reasonable thickness of leveling layer for the upper and lower prefabricated lane structures is 100 mm and 130 mm respectively.
Abstract：
A shield-driven tunnel is a longitudinal flexible structure prone to such issues as dislocation and axis deviation, which are contrary to the requirements for high precision in prefabricated construction. In view of this, the common practice is to correct and eliminate shield tunnel deformation-induced deviations by means of cast-inplace strips and leveling layers in conjunction with the synchronous construction process in shield tunnelling. In other words, it is to form a monolithic prefabricated and assembled structure of "prefabricated main body + small amount of cast-in-place component". However, the space inside the shield-driven tunnel is so limited that excessive cast-in-place strips and over-thick leveling layers are not economical or time-efficient, and would also take up valuable internal space. Therefore, the cast-in-place strips and leveling layers should be set up in a reasonable manner so that they meet the need to eliminate longitudinal uneven deformations in shield-driven tunnels without taking up too much space. In light of this, this paper analyzes the characteristics of longitudinal uneven deformations in shield-driven tunnels based on the measured axis deviations in Shanghai Zhuguang Road tunnel and extant relevant literatures, and combined with the construction process it proposes a reasonable solution to eliminate longitudinal uneven deformations in shield tunnels with prefabricated and assembled lane structures, as well as a reasonable value for the thickness of the leveling layer. The results show that as for the upper prefabricated lane structure, the cast-in-place concrete base with bonded rebars could eliminate most of longitudinal uneven deformations in shielddriven tunnels, while leveling layers could eliminate a small amount of longitudinal uneven deformations and assembly deviations. For the lower prefabricated lane structure, longitudinal uneven deformations and assembly deviations in the shield-driven tunnel could be eliminated with leveling layers. The reasonable thickness of leveling layer for the upper and lower prefabricated lane structures is 100 mm and 130 mm respectively.
LIU Nian
.Analysis of and Countermeasures against the Assembly Deviations of Prefabricated and Assembled Lane Structure in Double-deck Shield-driven Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(4): 210-217
2021, Vol. 58 