Method for lifting subway shield tunnel by polymer grouting

A method for lifting a subway shield tunnel by polymer grouting, comprising steps of:

• S1, detecting settlement of the shield tunnel (1), and determining a settlement location, a settlement range and a settlement amount;
• S2, drilling a row of isolation barrier holes (3) on both sides of a settlement repair area, and injecting quick-setting slurry into the isolation barrier holes (3), in such a manner that two isolation barriers (4) are formed after the quick-setting slurry is cured, which are used to restrain a soil body within the settlement repair area;
• S3, drilling grouting channel holes (5) from ground with an inclined hole guided drilling rig (2), and then drilling horizontal grouting holes (6) below the settlement;
• S4, connecting grouting pipes (8) to geotextile bags (7), and feeding the geotextile bags (7) into each of the grouting holes (6) in turn;
• S5, using a polymer grouting system (10) to inject polymer slurry into the geotextile bags (7) through the grouting pipes (8) in an order from two sides to middle, wherein the polymer slurry then expands to lift up a soil layer above and jack up a tunnel structure;
• and
• S6, after lifting, filling and sealing the grouting channel holes (5).