A construction method for a large circular caisson with a hyperbolic top entrance

Abstract

This invention provides a construction method for the top inlet of a large circular caisson with a hyperboloidal surface, comprising the following steps: S1, laying out and embedding reinforcing bars on a flat concrete surface according to an elliptical model, and then welding the reinforcing bars into a ring according to the elliptical model to form a circumferential reinforcing bar at the top inlet; S2, hoisting and placing the circumferential reinforcing bar at the top inlet and temporarily welding it together with the inner and outer reinforcing bars of the caisson wall; S3, installing axial reinforcing bars at the top inlet on the circumferential reinforcing bars at the top inlet; S4, installing cross-shaped horizontal and vertical H-beam back walls on the inner side of the circumferential reinforcing bars at the top inlet; S5, arranging spacers on the outer side of the circumferential reinforcing bars; S6, temporarily fixing timber with wire on the outer side of the spacers; S7, after completing the installation of tie bolts, installing the circumferential back reinforcement bars, which connect the timber into a ring; this method solves the problems of high construction cost and inconvenience of existing caisson pre-reserved top inlet construction.

Description

Technical Field

[0001] This invention relates to the field of caisson construction technology, and in particular to a construction method for the hyperboloid top inlet of a large circular caisson. Background Technology

[0002] In recent years, caisson construction technology has been widely used in bridge foundations, underground engineering, deep foundations of adjacent buildings, water conservancy projects, municipal engineering and other fields.

[0003] With the continuous development and expansion of urban underground space, large-scale caisson and pipe jacking construction technologies are becoming increasingly widespread. Not only are large and medium-sized coastal cities using caisson and pipe jacking, but even some smaller cities in the western and northern inland regions are employing this method. During caisson wall construction, steel sleeves need to be pre-embedded at the reserved top inlet position for pipe jacking, and then cast into the caisson wall. Before the caisson sinks, a brick-built reinforcement wall is constructed at the reserved top inlet, with H-beams welded to the inner side of the reinforcement wall as steel supports. The large diameter of the steel sleeves makes hoisting and installation difficult, and the fabrication and installation costs are high. When constructing the H-beam back beam after the steel sleeve installation, there is no open surface above, making it impossible to hoist the H-beams as a whole; installation must be done from the top inlet, leading to numerous potential problems such as weak overhead welding at the top. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a construction method for the hyperboloid top inlet of a large circular caisson, which solves the problem that existing caisson pre-reserved top inlets are inconvenient to construct.

[0005] According to an embodiment of the present invention, a construction method for the top inlet of a large circular caisson with a hyperboloidal surface includes the following steps: S1, laying out and embedding reinforcing bars on a flat concrete surface according to an elliptical model, using an arc-adjusting machine for preliminary bending of the reinforcing bars, and then welding the reinforcing bars into elliptical rings according to the elliptical model to form circumferential reinforcing bars at the top inlet; S2, hoisting and placing the circumferential reinforcing bars at the top inlet and temporarily welding them together with the inner and outer reinforcing bars of the caisson wall; S3, installing axial reinforcing bars at the top inlet on the circumferential reinforcing bars at the top inlet; S4, installing axial reinforcing bars at the top inlet on the circumferential reinforcing bars at the top inlet. The inner side is fitted with cross-shaped horizontal and vertical I-beam back walls, with each horizontal and vertical I-beam back wall end anchored 30cm into the concrete; S5, spacers are placed on the outside of the circumferential reinforcement; S6, the outside of the spacers is temporarily fixed with wire to the timber, and after the timber is fixed, holes are drilled in the timber to install tie bolts, which are welded to the well wall reinforcement; S7, after the tie bolts are installed, the circumferential back reinforcement is installed, which connects the timber into a ring; S8, steel pipe scaffolding is used to reinforce the formwork system.

[0006] Compared with existing technologies, this invention has the following advantages: Specifically, the horizontal and vertical H-beam back walls mainly provide the reaction force of the soil pressure at the top inlet of the hyperboloid, and the H-beams are easy and quick to install; the H-beams are directly anchored into the concrete without the need for pre-embedded steel bars, avoiding weak points in the welding of pre-embedded steel bars to the H-beams, thus improving the stability of the H-beams; and by splicing ellipses with wooden blocks, the use of steel sleeves is eliminated, ensuring the curvature of the two curved surfaces at the top inlet and meeting the requirements of the jacking equipment; the construction method of this large circular caisson hyperboloid top inlet is simple, has low construction costs, and reduces the safety risks of steel structure hoisting.

[0007] Furthermore, in step S1, after the elliptical steel bars are welded into a ring, support rods are set at the minor axis and major axis of the elliptical steel bar ring to serve as internal supports.

[0008] Preferably, in step S2, when hoisting the circumferential reinforcing rib at the top inlet, the angle between the circumferential reinforcing rib and the hole axis is 115.61°.

[0009] Preferably, in step S7, gaps are left between the wooden blocks forming the ring.

[0010] Preferably, in step S6, the timber square has a size of 5cm*8cm.

[0011] Preferably, in step S6, the circumferential spacing and axial spacing between the tie bolts are both 50cm. Detailed Implementation

[0012] The technical solutions of the present invention will be further described below with reference to the embodiments.

[0013] This invention proposes a construction method for the top inlet of a large circular caisson with a hyperboloidal surface, comprising the following steps: S1, laying out and embedding reinforcing bars on a flat concrete surface according to an elliptical model, using an arc-adjusting machine for initial bending of the reinforcing bars, and then welding the reinforcing bars into elliptical rings according to the elliptical model to form circumferential reinforcing bars at the top inlet; S2, hoisting and placing the circumferential reinforcing bars at the top inlet and temporarily welding them together with the inner and outer reinforcing bars of the caisson wall; S3, installing axial reinforcing bars at the top inlet on the circumferential reinforcing bars at the top inlet; S4, installing axial reinforcing bars at the top inlet on the inner side of the circumferential reinforcing bars at the top inlet. S5. Install cross-shaped horizontal and vertical I-beam back walls on the sides, with each horizontal and vertical I-beam back wall end anchored 30cm into the concrete; S6. Place spacers on the outside of the circumferential reinforcement; S7. Temporarily fix the timber with wire on the outside of the spacers. After the timber is fixed, drill holes in the timber with an electric drill to install tie bolts. Weld the tie bolts to the well wall reinforcement; S8. After the tie bolts are installed, install the circumferential back reinforcement, which connects the timber into a ring; S9. Reinforce the formwork system with steel pipe scaffolding.

[0014] Specifically, the horizontal and vertical H-beam back walls primarily provide the reaction force for the soil pressure at the hyperboloid top inlet, and the H-beams are easy and quick to install; the H-beams are directly anchored into the concrete without the need for pre-embedded reinforcing bars, avoiding weak points in the welding of pre-embedded reinforcing bars to the H-beams, thus improving the stability of the H-beams. Furthermore, the elliptical structure is constructed by splicing timber, eliminating the need for steel sleeves, ensuring the curvature of the two curved surfaces at the top inlet and meeting the requirements of the jacking equipment; the construction method for the hyperboloid top inlet of this large circular caisson is simple, with low construction costs, reducing the safety risks of steel structure hoisting.

[0015] Furthermore, in step S1, after the elliptical steel bars are welded into a ring, support rods are installed at the minor axis and major axis of the elliptical steel bar ring to provide internal support and prevent deformation of the elliptical steel bar ring.

[0016] Preferably, in step S2, when hoisting the circumferential reinforcing rib at the top inlet, the angle between the circumferential reinforcing rib and the hole axis is 115.61°.

[0017] Preferably, in step S7, gaps are left between the wooden blocks forming the ring, allowing gas to escape freely during concrete pouring, thus preventing the wooden blocks from floating.

[0018] Preferably, in step S6, the timber square has a size of 5cm*8cm.

[0019] Preferably, in step S6, the circumferential spacing and axial spacing between the tie bolts are both 50cm.

[0020] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A construction method for the hyperboloid top inlet of a large circular caisson, characterized in that, The steps include: S1. Lay out and embed steel bars on a flat concrete surface according to the elliptical model. Use an arc-adjusting machine to preliminarily adjust the steel bars, and then weld the steel bars into elliptical rings according to the elliptical model to form the top inlet circumferential reinforcing bars. S2. Hoist and install the top inlet circumferential reinforcing bar and temporarily weld it to the inner and outer steel bars of the well wall; S3. Install the top inlet axial reinforcing rib on the top inlet circumferential reinforcing rib; S4. Install cross-shaped horizontal and vertical I-beam back walls on the inner side of the top inlet circumferential reinforcing ribs. The ends of each horizontal and vertical I-beam back wall are anchored into the concrete for 30cm. S5. Place spacers on the outside of the circumferential reinforcement bars; S6. The outer side of the pad block is temporarily fixed with iron wire. After the wooden block is fixed, holes are drilled in the wooden block with an electric drill to install tie bolts. The tie bolts are welded to the well wall steel bars. S7. After completing the installation of the tie bolts, install the circumferential back reinforcement, which connects the timber into a ring. S8. Steel pipe scaffolding is used to reinforce the formwork system.

2. The construction method for the hyperboloid top inlet of a large circular caisson as described in claim 1, characterized in that, In step S1, after the elliptical steel bars are welded into a ring, support rods are installed at the minor axis and major axis of the elliptical steel bar ring to provide internal support.

3. The construction method for the hyperboloid top inlet of a large circular caisson as described in claim 1, characterized in that, In step S2, when hoisting the circumferential reinforcing rib at the top inlet, the angle between the circumferential reinforcing rib and the hole axis is 115.61°.

4. The construction method for the hyperboloid top inlet of a large circular caisson as described in claim 1, characterized in that, In step S7, gaps are left between the wooden blocks forming the ring.

5. The construction method for the hyperboloid top inlet of a large circular caisson as described in claim 1, characterized in that, In step S6, the dimensions of the timber are 5cm*8cm.

6. The construction method for the hyperboloid top inlet of a large circular caisson as described in claim 1, characterized in that, In step S6, the circumferential and axial spacing between the tie bolts are both 50cm.