Abstract Regarding the deep-hole grouting reinforcement measures for sand gushing and water inflow during con? struction of a Qingdao metro tunnel passing through a water-rich sand layer, the disturbance mechanism of deephole grouting reinforcement for construction of metro tunnels under these conditions is studied by FLAC3D numerical calculation and site measurement. Grouting depth and pressure should be determined properly since they have a significant effect on ground disturbance and deformation, and a grouting pressure of 1.4~1.5 MPa should be used for the water-rich sand layer in Qingdao. When the ground surface keeps heaving, the surface above the double-tube tunnel heaves in an "M" shape, the grouting pressure at the tunnel′s central line has an obvious effect on ground disturbance, and the maximum heaving occurs at the tunnel crown. The ground surface heaves rapidly at the early stage of grouting and subsides quickly when the working face is within a scope of -3D in front of the monitoring section, then the ground settlement slows down within a scope of -2D and gets faster within the scope of 1D after it passes through the monitoring section, finally it tends to be stable. The effects of grouting construction on a building is less compared to that of surface uplifting, and a building above the tunnel deforms in a positive curvature with the occurrence of ground deformation in an "M" shape; a reversed splayed crack occurs at the building wall when the building structure is damaged. Additionally, crown settlement and clearance convergence are fast when working face passes through the monitoring section and tend to decrease when it is within 2D scope away from the monitoring section,then stabilizes gradually within a scope of 3D.
Abstract：
Regarding the deep-hole grouting reinforcement measures for sand gushing and water inflow during con? struction of a Qingdao metro tunnel passing through a water-rich sand layer, the disturbance mechanism of deephole grouting reinforcement for construction of metro tunnels under these conditions is studied by FLAC3D numerical calculation and site measurement. Grouting depth and pressure should be determined properly since they have a significant effect on ground disturbance and deformation, and a grouting pressure of 1.4~1.5 MPa should be used for the water-rich sand layer in Qingdao. When the ground surface keeps heaving, the surface above the double-tube tunnel heaves in an "M" shape, the grouting pressure at the tunnel′s central line has an obvious effect on ground disturbance, and the maximum heaving occurs at the tunnel crown. The ground surface heaves rapidly at the early stage of grouting and subsides quickly when the working face is within a scope of -3D in front of the monitoring section, then the ground settlement slows down within a scope of -2D and gets faster within the scope of 1D after it passes through the monitoring section, finally it tends to be stable. The effects of grouting construction on a building is less compared to that of surface uplifting, and a building above the tunnel deforms in a positive curvature with the occurrence of ground deformation in an "M" shape; a reversed splayed crack occurs at the building wall when the building structure is damaged. Additionally, crown settlement and clearance convergence are fast when working face passes through the monitoring section and tend to decrease when it is within 2D scope away from the monitoring section,then stabilizes gradually within a scope of 3D.
2018, Vol. 55 