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CN-115234245-B - Shallow buried tunnel supporting structure

CN115234245BCN 115234245 BCN115234245 BCN 115234245BCN-115234245-B

Abstract

The invention discloses an excavation supporting method and supporting structure for a shallow-buried tunnel to penetrate through a water-rich stratum, and relates to the field of tunnel engineering. The method has the technical scheme that the method comprises the steps of drilling holes on a working surface right above the tunnel, taking the drilled holes as drainage wells for drainage, excavating the tunnel after the groundwater level is reduced, drilling a drilling pull rod hole, placing a reinforcement cage and pull rod reinforcement in the drilled holes and the pull rod hole, and pouring concrete to form an integral support structure, wherein the support structures are arranged at intervals along the axis of the tunnel. The shallow-buried-depth tunnel supporting structure is obtained by construction through the shallow-buried-depth tunnel excavation supporting method. The invention uses the drilling holes as drainage wells to drain water, has high advanced drainage efficiency, does not occupy the straight construction period, and has good safety and stability when the supporting structure is buried in soil. The method is used for excavating and supporting the shallow-buried tunnel penetrating through the water-rich stratum.

Inventors

  • LI ZHENG

Assignees

  • 中国电建集团成都勘测设计研究院有限公司

Dates

Publication Date
20260505
Application Date
20220808

Claims (9)

  1. 1. A shallow-buried-depth tunnel supporting structure is characterized in that vertical pile holes are formed in the outer sides of two side walls of a tunnel respectively, the upper ends of the pile holes penetrate out of the ground surface, the lower ends of the pile holes are lower than the corresponding elevation of a bottom plate of the tunnel, at least two pull rod holes (4) are formed between the hole wall of the tunnel and the pile holes on the same side, the center lines of the pull rod holes (4) are located on vertical surfaces where the two pile holes are located, the pull rod holes (4) on the same section of the tunnel are symmetrically arranged along the vertical center axis of the tunnel, a reinforcement cage (3) is arranged in the pile holes, pull rod reinforcing steel bars (5) are arranged in the pull rod holes (4), the front ends of the pull rod reinforcing steel bars (5) are connected with the reinforcement cage (3), concrete is poured into the drill holes and the pull rod holes (4) to form an integral supporting structure, the center lines of the two pile holes of the same supporting structure are equal to the axial distance of the tunnel, the support structure is arranged at intervals along the axial lines of the tunnel, a mesh is hung on the inner wall of the tunnel, the back end of the reinforcement cage (5) is fixedly connected with the rear end of the reinforcement steel bar (5), the mesh is fixedly connected with the back end of the reinforcement (6), and the support structure is formed to be a concrete supporting structure.
  2. 2. The shallow-buried tunnel supporting structure of claim 1, wherein the vertical surfaces of the supporting structures are parallel to each other.
  3. 3. The shallow-buried tunnel supporting structure according to claim 2, wherein the planes of the central lines of the two pile holes of the same supporting structure are perpendicular to the axis of the tunnel.
  4. 4. The shallow-buried tunnel support structure of claim 2 wherein each support structure is equally spaced along the axis of the tunnel.
  5. 5. The shallow tunnel supporting structure according to any one of claims 1 to 4, wherein the reinforcement cage (3) in the pile hole comprises vertically arranged main reinforcements and stirrups arranged along a horizontal plane, the reinforcement cage (3) is rectangular in horizontal section, and the long side of the rectangle is parallel to the vertical plane where the central lines of the two pile holes are located.
  6. 6. The shallow tunnel supporting structure according to any one of claims 1 to 4, wherein hooks are arranged at the front ends of the pull rod steel bars (5) and are connected with the steel bar framework (3), and the rear ends of the pull rod steel bars (5) are welded with the steel bar meshes.
  7. 7. A shallow-buried tunnel supporting structure according to any one of claims 1 to 4, wherein the pull rod holes (4) of the supporting structure are symmetrically arranged along the vertical central axis of the tunnel, and the extension lines of the central lines of the pull rod holes (4) pass through the circle center of the arch crown of the tunnel.
  8. 8. The shallow-buried tunnel supporting structure according to claim 7, wherein the number of the pull rod holes (4) of the same supporting structure is 4-8 and even.
  9. 9. The shallow-buried tunnel support structure according to any one of claims 1 to 4, wherein the distance between the pile hole and the vertical surface of the adjacent tunnel side wall is 20 to 40cm, and the distance between the adjacent support structures is 50 to 150cm.

Description

Shallow buried tunnel supporting structure Technical Field The invention relates to the field of tunnel engineering, in particular to an excavation supporting method and a supporting structure for a shallow-buried-depth tunnel in penetrating through a water-rich stratum. Background The shallow-buried tunnel is difficult to excavate by penetrating through the water-rich stratum, the construction process is complex, and safety accidents such as tunnel collapse and the like are easy to occur. At present, a construction process of combining advanced drainage with advanced support is mainly adopted, advanced drainage holes are drilled in a tunnel face to pre-drain underground water, and after tunnel excavation, preliminary support is carried out by matching with steel supports, reinforcing steel meshes and sprayed concrete, so that the aim of smooth excavation is fulfilled. The construction process has the defects that the first and advanced drainage effects are limited, particularly for a hole section with abundant underground water, the advanced drainage time of the tunnel face is long, the underground water drainage time cannot be accurately judged, and the construction progress is delayed and the construction cost is increased. Secondly, the advanced support construction occupies a straight construction period, and the construction progress is retarded. Thirdly, the steel support needs to be prefabricated into the designed shape and size, and the steel support cannot be closely attached to the tunnel excavation outline, so that the supporting effect is poor. Fourth, the reinforcing bar net piece lays in the outside of steel support, exists great space between surrounding rock, is unfavorable for the long-term stability of hole top surrounding rock. And fifthly, when the tunnel is excavated by blasting, the steel support close to the tunnel face is easy to damage, so that the supporting structure is damaged, and potential safety hazards are caused. Sixth, the steel support is immersed in groundwater and the slag transport vehicle is rolled down, the bottom of the steel support is easily hollowed out, and accordingly larger potential safety hazards are caused. Disclosure of Invention The invention firstly provides a shallow-buried-depth tunnel excavation supporting method, which aims to improve advanced drainage efficiency and stability of a supporting structure. The technical scheme adopted for achieving the purpose is that the shallow-buried-depth tunnel excavation supporting method comprises the following steps of: S1, leveling the site, determining drilling points, namely clearing a working surface on the earth surface right above the tunnel, and arranging the drilling points outside the projection of the working surface along the side wall of the tunnel. The drilling points are arranged along the axial direction of the tunnel, the distance between each row of drilling points and the vertical plane where the adjacent side wall of the tunnel is located is 20-40 cm, and the horizontal distance between each row of drilling points is 50-150 cm. S2, respectively burying pile casings for all drilling points, and drilling by adopting a static mud wall-protecting drilling process, wherein the height of the bottom of the drilled holes is lower than that of the bottom plate of the tunnel. For example: inner diameter ratio of casing the diameter of the pile is 20-40 cm, the burial depth of the pile casing is 200-400 cm. S3, cleaning the drilled holes and dewatering, namely cleaning the drilled holes, and draining water as a drainage well after cleaning the drilled holes to reduce the water level. For example, after the drilling hole reaches the designed depth, the depth and position of the hole are checked and cleaned, the hole is cleaned by adopting a slurry pumping method, after the hole is cleaned, the well pipe is put into the drilling hole, and then the drain pipe is put into the well pipe and is externally connected with a water pump for draining. And S4, tunnel excavation construction, namely after the water level of the drilled holes in the single-cycle excavation length range of the tunnel is lower than the elevation of the bottom plate of the tunnel, performing single-cycle excavation of the tunnel, and excavating to the designed section size. S5, selecting one drilling hole on two sides of the axis of the tunnel respectively to form a group, selecting at least one group of drilling holes on a single-cycle excavated hole section of the tunnel, and placing a reinforcement cage in each group of drilling holes. Further, the center lines of the two drilling holes in the same group are equidistant from the tunnel axis. Further, the vertical plane where the central lines of the two drilling holes in the same group are positioned is perpendicular to the axis of the tunnel. Further, the sets of boreholes are equally spaced along the axis of the tunnel. For example, the steel reinforcement framework comprises main r