Constant-pressure support system for immersed-tube section

Abstract

The present invention applies to the technical field of immersed tube tunnel construction. Provided is a constant-pressure support system for an immersed-tube section. The constant-pressure support system uses a method for preventing cracks in an immersed-tube section during lightering. The constant-pressure support system for use in the lightering of the immersed-tube section proposed in the present invention applies to the technical field of immersed tube tunnel construction, and has relatively high safety and wide applicability.

Description

A constant pressure support system for immersed tunnel sections Technical Field

[0001] This invention relates to a constant pressure support system for immersed tunnel sections, applicable to the field of immersed tunnel construction technology. Background Technology

[0002] Immersed tunnel construction technology is an engineering technique that uses specially designed immersed tubes (usually large precast concrete or steel segments) to build underwater tunnels. This technology is mainly used in the construction of tunnels crossing rivers, straits, ports, and other bodies of water, especially when bridge construction is inconvenient or technically infeasible. Immersed tunnel technology consists of multiple precast tunnel segments. These segments are manufactured on land, transported by ship to a designated location, and then immersed in pre-prepared trenches for connection and sealing, forming a continuous tunnel structure.

[0003] Currently, prefabricated immersed tunnel sections are generally transported to the project site from navigable waters near the production site using semi-submersible barges. During transportation, because the support system does not account for vibrations during navigation, the immersed tunnel support structure and the immersed tunnel itself experience relative displacement under the influence of water currents, waves, and strong winds. In particular, the impact of waves on the hull causes significant stress on the immersed tunnel and its support structure, leading to cracking of the immersed tunnel concrete and compromising the integrity of the immersed tunnel and the safety of the tunnel structure. Furthermore, the forced vibrations of the immersed tunnel during hull swaying also adversely affect the fatigue stability of the tunnel segment structure.

[0004] During the transport of immersed tunnel sections, steel cables, chains, wedges, and other equipment are generally used to provide lateral constraints parallel to the hull plane (hereinafter referred to as transverse constraints), limiting the relative lateral displacement between the immersed tunnel section and the supporting device. When the immersed tunnel section and the supporting device are relatively stationary, the lateral constraint is still provided by the static friction between the immersed tunnel section and the supporting device. Due to the poor tensile strength of concrete, static friction can cause the immersed tunnel section to tear.

[0005] Therefore, it is necessary to adopt a constant pressure support system that reduces the vibration of the immersed tube and prevents cracks from forming in the immersed tube.

[0006] Summary of the Invention

[0007] The purpose of this invention is to provide a constant pressure support system for immersed tunnel sections, which is applicable to the field of immersed tunnel construction technology, has strong safety, and wide applicability.

[0008] The objective of this invention can be achieved by the following methods:

[0009] S101, the immersed tube section is placed horizontally on the constant pressure support system. The constant pressure support system includes n constant pressure supports. Pressure sensors 1 are arranged in the constant pressure supports. Before the hull is launched, the pressure value p of the pressure sensor 1 in the constant pressure support corresponding to the upper plate of the support system is recorded. The constant pressure support with the largest pressure value p is selected.

[0010] S102, An inclination measuring instrument is arranged inside the immersed tube section. During the barge transportation process after the hull is launched, the inclination angle θ between the immersed tube section and the horizontal plane is recorded at intervals Δt.

[0011] S103, An acceleration measuring instrument is installed inside the immersed tunnel section. During the barge transportation process after the hull is launched, the acceleration a corresponding to the immersed tunnel section in the vertical direction is recorded at intervals Δt. z The vertically downward direction is considered positive.

[0012] S104, control the hydraulic lifting height and lubricant pump of the constant pressure support system during the transport of the immersed tube section, so that the tilt angle θ between the immersed tube section and the horizontal plane, and the static friction coefficient μ between the immersed tube section material and the support device material, satisfy control condition (1).

[0013] In the formula, η is the safety factor, with a value ranging from 0.5 to 0.8, and f tk This is the standard value for the tensile strength of concrete.

[0014] Furthermore, the constant pressure support system for transporting immersed tunnel sections is characterized in that it comprises n constant pressure supports, each constant pressure support including a support device, a control device, an overflow valve, a constant pressure valve, an oil pump, an oil tank, a lubricant pump, and a lubricant tank. The support device is frustum-shaped, with a steel outer shell. An annular rubber ring is installed inside the support device, and a pressure sensor 1 is installed on the annular rubber ring. A top plate is located above the annular rubber ring, and the top plate is evenly distributed... The lubricant pump has a groove on one end connected to the groove on the upper top plate and a lubricant tank on the other end. A rigid shaft is installed inside the annular rubber ring. The upper top plate of the support device is hinged to the rigid shaft. A middle plate is installed on the upper part of the annular rubber ring. The upper top plate and the middle plate can slide in the support device. The lower part of the middle plate is a liquid tank. A pressure sensor 2 is installed on the lower part of the middle plate. The liquid tank is connected to the overflow valve through an oil pipe. The overflow valve is connected to the oil pump and the constant pressure valve through an oil pipe. The constant pressure valve is connected to the oil tank through an oil pipe.

[0015] Furthermore, in S101 above, the immersed tube section is placed on the top plate of the support device using a static friction constraint method. Attached Figure Description

[0016] Figure 1: A flowchart of a method for preventing cracks in immersed tunnel sections during transport using a constant pressure support system for immersed tunnel sections according to the present invention.

[0017] Figure 2: A schematic diagram of the constant pressure support structure of a constant pressure support system for immersed tube sections according to the present invention. In the figure: 1. Liquid tank; 2. Steel outer shell; 3. Rigid shaft; 4. Top plate; 5. Pressure sensor 1; 6. Lubricant pump; 7. Lubricant tank; 8. Control system; 9. Pressure sensor 2; 10. Oil tank; 11. Constant pressure valve; 12. Oil pump; 13. Overflow valve; 14. Middle plate. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings; it should be understood that the specific embodiments given herein are only for illustration and explanation of the present invention and cannot be used to limit the present invention.

[0019] The following is a specific embodiment of a constant pressure support system for immersed tunnel sections.

[0020] Figure 1 shows a flowchart of a constant pressure support system for immersed tunnel sections according to the present invention.

[0021] Example 1:

[0022] This embodiment utilizes the main tunnel of a project on the Shenzhen Riverside Expressway. The immersed tunnel section is 2280m long, with eight lanes on both sides. Each standard section of the immersed tunnel segment is 80m long, 42.8m wide, and 10.9m high, with a total weight of approximately 6000 tons. The immersed tunnel segments are constructed using C50 concrete, with a concrete tensile strength standard value f. tk =2.64 N / mm 2 Under conditions without lubricant, the static friction coefficient between concrete and steel is μ = 0.6.

[0023] The immersed tunnel section is placed on the support system. When the immersed tunnel section is stationary relative to the support system, the static friction between the immersed tunnel section and the support system provides horizontal constraint. When the immersed tunnel section moves relative to the support system, the wedge-shaped device provides horizontal constraint.

[0024] S101, the immersed tunnel section is placed horizontally on the constant pressure support system, which includes 21 constant pressure supports. Pressure sensors 1 are installed inside the constant pressure supports. Before the hull is launched, the pressure value of the pressure sensor 1 inside the constant pressure support corresponding to the upper plate of the support system is recorded. The constant pressure support with the largest pressure value has a pressure value p = 2.15 N / mm. 2 ;

[0025] S102, an inclination measuring instrument is installed inside the immersed tunnel section. During the barge transportation process after the hull is launched, the inclination angle θ between the immersed tunnel section and the horizontal plane is recorded at intervals Δt = 5s. The data for one time period is as follows.

[0026] S103, An acceleration measuring instrument is installed inside the immersed tunnel section. During the barge transportation process after the hull is launched, the acceleration 'a' of the immersed tunnel section in the vertical direction is recorded at intervals Δt = 5s. z With vertical downwards as the positive direction, the data for one time period is as follows.

[0027] S104, control the hydraulic lifting height and lubricant pump of the constant pressure support system during the transport of the immersed tube section, so that the tilt angle θ between the immersed tube section and the horizontal plane, and the static friction coefficient μ between the immersed tube section material and the support device material, satisfy control condition (1).

[0028] In the formula, η is the safety factor, which is 0.5 in this embodiment.

[0029] At t = 20 s, the left side of the control condition inequality is 1.28 N / mm. 2 The elevation has already approached the limit specified on the right by less than 5%. Therefore, the lifting height of the hydraulic system on the side with the higher elevation of the immersed tunnel section is further increased by the control system, thereby increasing the tilt angle of the immersed tunnel section with the horizontal plane. This ensures that the maximum static friction between the immersed tunnel section and the support system remains less than 1.32 N / mm. 2 .

[0030] In this embodiment, the maximum pressure value of the constant pressure support is close to the standard value of the tensile strength of concrete. Therefore, by adjusting the inclination angle between the immersed tube section and the horizontal plane, the maximum static friction force between the immersed tube section and the support device can be finely adjusted, thereby preventing the generation of cracks.

[0031] Example 2:

[0032] This embodiment is based on the Shenzhen-Zhongshan Bridge project. The standard section of the immersed tunnel segment is 165m long, 46m wide, and 10.6m high, with a total weight of approximately 11,000 tons. The immersed tunnel segment uses C50 concrete, and the standard value of the concrete tensile strength f... t k =2.64 N / mm 2Without lubricant, the static friction coefficient between concrete and steel is μ1 = 0.6. With lubricant, the static friction coefficient between concrete and steel is μ2 = 0.1.

[0033] S101, the immersed tunnel section is placed horizontally on the constant pressure support system, which includes 32 constant pressure supports. Pressure sensors 1 are installed inside the constant pressure supports. Before the hull is launched, the pressure value of the pressure sensor 1 inside the constant pressure support corresponding to the upper plate of the support system is recorded. The constant pressure support with the largest pressure value has a pressure value p = 5.16 N / mm. 2 ;

[0034] S102, an inclination measuring instrument is installed inside the immersed tunnel section. During the barge transportation process after the hull is launched, the inclination angle θ between the immersed tunnel section and the horizontal plane is recorded at intervals Δt = 5s. The data for one time period is as follows.

[0035] S103, An acceleration measuring instrument is installed inside the immersed tunnel section. During the barge transportation process after the hull is launched, the acceleration 'a' of the immersed tunnel section in the vertical direction is recorded at intervals Δt = 5s. z With vertical downwards as the positive direction, the data for one time period is as follows.

[0036] S104, control the hydraulic lifting height and lubricant pump of the support device in the constant pressure support system during the transport of the immersed tube section, so that the tilt angle θ between the immersed tube section and the horizontal plane, and the static friction coefficient μ = μ2 = 0.1 between the immersed tube section material and the support device material, satisfy control condition (1).

[0037] In the formula, η is the safety factor, which is 0.5 in this embodiment.

[0038] In this embodiment, the maximum pressure value of the constant pressure support is much larger than the standard value of the tensile strength of concrete. Therefore, it is impossible to fine-tune the maximum static friction between the immersed tunnel section and the support device by adjusting the tilt angle of the immersed tunnel section to the horizontal plane. Injecting lubricant between the immersed tunnel section and the top plate of the support device using a lubricant pump significantly reduces the maximum static friction between the immersed tunnel section and the support device, thereby preventing crack formation.

[0039] In the above embodiments, the present invention discloses a constant pressure support system for transporting immersed tunnel sections, including a method for preventing cracks in the immersed tunnel sections during transport. The constant pressure support system for transporting immersed tunnel sections proposed in the present invention is applicable to the field of immersed tunnel construction technology, has strong safety, and wide applicability.

[0040] The above description is a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A constant pressure support system for transporting immersed tunnel sections, characterized in that, This includes a method for preventing cracks in immersed tunnel sections during transport, the method comprising the following steps: S101, select the constant pressure support with the highest pressure value; The specific content of selecting the constant pressure support with the largest pressure value p includes: placing the immersed tube section horizontally in the constant pressure support system, the constant pressure support system including n constant pressure supports, and arranging pressure sensor 1 in the constant pressure support. Before the hull is launched, the pressure value p of the pressure sensor 1 in the constant pressure support corresponding to the upper plate of the support system is recorded, and the constant pressure support with the largest pressure value p is selected. S102, record the inclination angle of the immersed tunnel section relative to the horizontal plane; The recording of the tilt angle between the immersed tunnel section and the horizontal plane specifically includes: arranging an tilt angle measuring instrument inside the immersed tunnel section; and recording the tilt angle θ between the immersed tunnel section and the horizontal plane at intervals Δt during the barge transportation process after the hull is launched. S103, record the vertical acceleration of the immersed tunnel segment; The recording of the vertical acceleration of the immersed tunnel segment specifically includes: installing an acceleration measuring instrument inside the immersed tunnel segment; and recording the corresponding vertical acceleration 'a' of the immersed tunnel segment at intervals Δt during the barge transport process after the hull is launched. z The vertically downward direction is considered positive. S104 controls the maximum static friction force; The control of maximum static friction specifically includes arranging a hydraulic system and a lubricant pump inside the constant pressure support, controlling the lifting height of the hydraulic system and the opening and closing of the lubricant pump during the transport of the immersed tube section, so that the tilt angle θ between the immersed tube section and the horizontal plane, and the static friction coefficient μ between the immersed tube section material and the support device material, satisfy control condition (1). In the formula, η is the safety factor, with a value ranging from 0.5 to 0.8, and f tk This is the standard value for the tensile strength of concrete.

2. The constant pressure support system for transporting immersed tunnel sections according to claim 1, characterized in that... The aforementioned constant pressure support system for transporting immersed tunnel sections includes n constant pressure supports. Each constant pressure support includes a support device, a control device, an overflow valve, a constant pressure valve, an oil pump, an oil tank, a lubricant pump, and a lubricant tank. The support device is frustum-shaped and has a steel outer shell. An annular rubber ring is installed inside the support device, and a pressure sensor 1 is installed on the annular rubber ring. A top plate is located above the annular rubber ring, and grooves are evenly distributed on the top plate. One end of the lubricant pump is connected to the grooves on the top plate, and the other end is connected to the lubricant tank. A rigid shaft is installed inside the annular rubber ring, and the top plate of the support device is hinged to the rigid shaft. A middle plate is installed below the annular rubber ring. The top plate and the middle plate can slide within the support device. The lower part of the middle plate is a liquid tank, and a pressure sensor 2 is installed below the middle plate. The liquid tank is connected to the overflow valve via an oil pipe. The overflow valve is connected to the oil pump and the constant pressure valve via an oil pipe. The constant pressure valve is connected to the oil tank via an oil pipe.

3. The constant pressure support system for transporting immersed tunnel sections according to claim 1, characterized in that, The immersed tube section is placed on the top plate of the support device using a static friction constraint method.

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