Construction method for comprehensive tunnel entering structure of large-span tunnel penetrating shallow-buried bias-pressure loose accumulation body

Construction method for comprehensive tunnel entering structure of large-span tunnel penetrating shallow-buried bias-pressure loose accumulation body

  • CN 105,840,207 B
  • Filed: 03/24/2016
  • Issued: 04/28/2020
  • Est. Priority Date: 03/24/2016
  • Status: Active Grant
First Claim
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1. A construction method for a comprehensive tunnel entering structure of a large-span tunnel penetrating through a shallow-buried bias loose accumulation body is characterized by comprising the following construction steps:

  • 1) construction of a bearing pile at the bottom of the tunnel;

    according to the position and the trend of a tunnel opening, pile foundations are arranged to be punched, high-pressure rotary spraying piles are punched downwards from the top surface of a loose accumulation body (16), high-pressure rotary spraying pressure is increased at the position of a grout layer on the outer side of the tunnel during construction, bottom bearing piles (11) are formed by downward construction from the elevation of the top surface of a bottom grout layer (4), and the plane punching range of the bearing piles (11) comprises the inner side and the outer side of the tunnel opening and the bottom of a back-pressure retaining wall (12);

    2) and (3) slurry-solidified layer construction;

    after the construction of the bottom bearing pile (11) is completed, grouting holes (10) are punched downwards from the top surface of the loose accumulation body (16), and grouting is performed on the outer side of the tunnel supporting structure in sections to form a top grout-fixing layer (3), a bottom grout-fixing layer (4) and a side grout-fixing layer (5);

    3) constructing an inner slurry-solidified retaining wall (1) and an outer slurry-solidified retaining wall (2);

    1-2 rows of high-pressure jet grouting piles are arranged downwards from the top surface of a loose accumulation body (16) to a lower stable soil layer outside a slurry-solid layer (5) on the side surface of the tunnel, the longitudinal direction of the high-pressure jet grouting piles is parallel to the direction of the tunnel, an inner slurry-solid retaining wall (1) and an outer slurry-solid retaining wall (2) are formed, and the thickness of the loose accumulation body (16) at the position of the outer slurry-solid retaining wall (2) is smaller than that of the loose accumulation body (16) at the position of the inner slurry-solid retaining wall (1); and

    the top parts of the inner grout-fixed retaining wall (1) and the outer grout-fixed retaining wall (2) are respectively provided with a crown beam (8);

    4) construction of the back pressure retaining wall (12);

    after the strength of the inner side slurry-fixed retaining wall (1) and the outer side slurry-fixed retaining wall (2) meets the design requirement, a back pressure retaining wall foundation (15) is dug outside the outer side slurry-fixed retaining wall (2) at the tunnel entrance part, and construction of the back pressure retaining wall (12) is carried out according to the type of the back pressure retaining wall;

    5) and (3) drainage body construction;

    a drain hole is drilled from the wall surface of the back pressure retaining wall (12) to the loose accumulation body (16), a drain hose is inserted to form an oblique drain body (14), the oblique drain body (14) adopts a plastic drain pipe, and the extending end of the plastic drain pipe is positioned outside the wall surface of the back pressure retaining wall (12);

    6) and (3) construction of oblique anchoring ribs;

    an inclined anchoring rib body (13) is arranged in the soil body behind the wall along the wall surface of the back pressure retaining wall (12);

    7) constructing a pipe shed advanced conduit (7);

    after the construction of a slurry-solid layer on the outer side of the tunnel supporting structure is finished, laying an advanced guide pipe (7);

    8) construction of the oblique reinforcement body (9);

    arranging an oblique reinforcement body (9) in a supporting structure in the tunnel, wherein the oblique reinforcement body (9) is arranged in a loose accumulation body (16) from the inner side of the tunnel supporting structure, the oblique reinforcement body (9) is inserted into the loose accumulation body (16) at the outer side through a top grout layer (3), and the oblique reinforcement body (9) adopts a steel pipe with an opening on the side wall or a fully-bonded anchor rod;

    9) construction of the pipe shed (6);

    selecting steel according to design size requirements and strength requirements, enabling the self temperatures of the pipes and the pipe fittings to be consistent with the ambient temperature of a construction site, performing a water pressing test before pouring of the pipe shed concrete, checking whether mechanical equipment is normal, and simultaneously adopting 3-5 grouting pipes to synchronously perform grouting in the pipe shed formwork.

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