Exploration and Grouting of Large-Scale Water Capsule in the Fault Fracture Zone of Yonglian Tunnel

A large-scale water capsule was formed after 8 times inrush of mud and water in Yonglian tunnel. The capsule seriously inhabited the construction of the tunnel. By combining with the geological conditions in tunnel site, the causes and characteristics of the water capsule were analyzed. Its spatial location and size were explorated by comprehensive exploration methods. In order to control the water capsule, the treatment scheme composed by full-face curtain grouting in left tunnel and decompression by drainage in right tunnel was made, and the composite and controlling grouting methods were proposed. The composite and controlling grouting technology was applied in the treatment. It was composed by grouting parameters selection, grouting material and technology optimization by means of numerical simulation, model experiment and SEM microscopic experiment. By means of the grouting effect examination methods including P-Q-t curve, examination holes, surrounding rock deformation monitoring and excavation, the water capsule was proved to be treated successfully. The engineering case provides a reference for the similar engineering to some extent.