Influence of Grouting Sequence on the Correction Effect of Horizontal Tunnel Displacement by Grouting in Granite Residual Soil

Abstract

Shield tunnels are vulnerable to large displacements induced by surrounding environmental changes. Grouting is an effective way to correct excessive shield tunnel displacement, while the grouting scheme design, especially the grouting sequence, is the key factor affecting the correction efficiency. A finite element simulation method considering the construction of multiple grouting zones is verified by the engineering case of Shenzhen Metro Line 1, and the influence of the grouting sequence on the correction effect on the horizontal tunnel displacement is further studied. The results show that the proper grouting efficiency of sandy clay, completely decomposed granite, and strongly decomposed granite is 5.5%, 2.8%, and 1.1%, respectively. The adjacent newly-built grouting zones are significantly constrained by the reinforcement created during the preceding grouting process. It is more efficient to correct excessive tunnel displacement in the “from far to near” sequence and excessive tunnel convergence in the “from near to far” sequence with increasing reinforcement stiffness. The correction effect improves greatly as the elastic modulus of the reinforcement increases up to 100 MPa.