Polymer bag grouting method for repairing settlement of underground pipelines

A polymer bag grouting method for repairing a settlement of an underground pipeline, wherein in order to repair the settlement of the underground pipeline, a settled pipeline section is uplifted, and a polymer material is injected into soil below the pipeline to fill a cavity caused by uplifting the settled pipeline section and to reinforce a soft soil layer surrounding the settled pipeline section;

• the polymer bag grouting method comprises steps of:
• (1) completely detecting the underground pipeline with a ground penetrating radar or a closed circuit television, and determining a location of the settled pipeline section and a settlement value of the settled pipeline section;
• (2) drilling a plurality of holes for containing bags, at a bottom part of the settled pipeline section which needs to be uplifted, along a radial direction of a settling end of the settled pipeline section;
• (3) placing first grouting pipes respectively at an opening of each of the bags;
• fixing the opening of each bag on the respective first grouting pipe by a circular hoop;
• and placing each of the bags which is tied up into each of the holes;
• (4) injecting the polymer material, which is a two-component expansive polymer material, successively into each of the bags by the respective first grouting pipes;
• (5) rapidly expanding and solidifying in the bags, by the polymer material, so as to generate a huge expansive force to uplift the settled pipeline section;
• (6) drilling a plurality of grouting holes at middle positions between each two holes, wherein each grouting hole has a diameter of 1.6 cm and is so deep as to penetrate a wall of the settled pipeline section;
• and inserting second grouting pipes respectively into the grouting holes;
• and
• (7) injecting the polymer material to the cavity outside the pipeline by the second grouting pipes;
• rapidly expanding and solidifying after reacting, by the polymer material, so as to fill the cavity caused by uplifting the settled pipeline section and effectively reinforce the soft soil layer surrounding the settled pipeline section.