Coupling analysis method of grouting construction with deformation response of adjacent existing tunnel

In the new tunnel under close distance through the existing tunnel risk source, the grouting scheme developed to compensate for stratum losses is still based on empirical methods, relying on the overburden thickness of existing tunnels. This can potentially lead to an excessively high or low probability of uplift of existing tunnels. Proposing a coupled deformation analysis method between the grouting construction and adjacent existing tunnels is of great theoretical significance for developing grouting schemes. In order to reasonably limit the design parameters of grouting construction, based on the theory of fluid–solid coupling elastic pore-column expansion and the theory of random media, the calculation method of stratum displacement which simultaneously considers the coexistence of grout compaction expansion and permeability diffusion mode is derived, and the accuracy of the calculation method is verified by engineering examples. The accuracy of this calculation method was verified through engineering examples. Combined with the deformation coordination condition, the existing tunnel is regarded as an elastic Euler-Bernoulli continuous beam, and the finite element coupling balance equation of the interaction between the existing tunnel and the surrounding soil is obtained. Based on this, a coupling calculation model of the grouting construction and the deformation response of the adjacent existing tunnel is established. Combined with three times of grouting construction examples in the shield tunneling project of Beijing Metro Line 12 under the existing airport line, the reliability of the coupling calculation model to determine the grouting construction parameters is verified. The calculation parameters in the coupling calculation model have clear physical meanings, which can provide a theoretical basis for the grouting design of similar risk source projects