Influence of grouting on rehabilitation of an over-deformed shield tunnel lining in spatially variable soil

Numerical analysis of ground surface settlement induced by shield tunnelling considering the soil parameter spatial variability in loess strata

“…Table 3 lists the geotechnical parameters for each soil layer. These soils were considered elastic-plastic media to adopt the widely used Mohr-Coulomb failure criterion and follow the nonassociated flow rule employed in numerical simulations with the random field analysis (Huang et al 2015;Cheng et al 2019b;Zhang et al 2022a). The tunnel lining was modelled as an elastic continuous ring structure.…”

“…Various theoretical autocorrelation functions typically discussed in the literature (Phoon et al 2003;Kim and Sitar 2013) have been employed to describe the spatial autocorrelation of soil parameters. Owing to its simplicity and ease of implementation in random fields, a single exponential function has been extensively utilised to investigate the effect of spatial variability on tunnelling mechanics and deformation (Huang et al 2017;Zhang et al 2022a;Zhao et al 2018). The correlation matrix can be expressed using Eq.…”

New indices of the recovery effect of the large deformation shield tunnel based on a light-disturbance grouting model test

“…Figure 2 presents the fundamental information regarding the soil box. The tunnel prototype employed in the test represented a typical metro shield tunnel in Shanghai [5], which is positioned at a burial depth equivalent to two times the outer diameter of the tunnel (denoted as D). Fifteen lining rings were utilized in the test, with only the five rings in the middle (i.e., rings 6-10) featuring longitudinal joints due to assembly from segments, while the remaining rings were homogeneous.…”

“…Unlike traditional structural reinforcement methods such as steel plate bonding [4], which solely enhance the structural stiffness and bearing capacity without addressing deformation, the grouting technique exerts additional stresses on both sides of the tunnel, effectively mitigating deformation and achieving the intended rehabilitation objectives. However, solely relying on transverse convergence as the primary evaluation index for assessing the grouting effect, which is a common practice for its simplicity and convenience, is not entirely reasonable IOP Publishing doi:10.1088/1755-1315/1333/1/012001 2 [5]. Previous studies have revealed that the grouting process may increase the segment dislocation while reducing the transverse convergence [6].…”

“…Ideally, the injection of a certain volume of slurry can induce a change in the corresponding volume in the tunnel cross-section. In practiccal applications, due to the spatial variability of the soil and the uncertainty generated by the grouting process [5], the injected slurry only partially serves to the change in volume of the tunnel cross-section. Therefore, additional indexes must be established to evaluate the grouting effect, including considerations of joint behavior and transfer action of the slurry.…”