The invention discloses a method for laying a large-
diameter drainage
pipe parallel to the upper part of an existing subway tunnel structure, which comprises the following steps: step 1, using a mixture of
cement and water glass to reinforce the bottom of the trench through a layered grouting process
Processing; step 2, construction and support of Larsen steel sheet piles; using Larsen steel sheet piles as
enclosure piles; step 3, excavating and setting steel supports and steel purlins, steel supports are fixedly connected with Larsen steel sheet piles through section steel; steps 4. Dig to the bottom of the foundation pit and tamp the pipeline foundation; step 5. Lay
glass fiber reinforced plastic sand-filled large-
diameter pipelines on the pipeline foundation, and construct the main structure. After the main structure reaches the design strength, it will be backfilled from bottom to top until Backfill to the design
ground level; step 6, pull out the Larsen steel
sheet pile, and fill the gap after the Larsen steel
sheet pile or steel
purlin is pulled out. The invention has fast construction speed and can ensure that the displacement of the top of the surrounding protection
pile and the settlement of the surrounding ground are within an acceptable range during the excavation of the foundation pit.