Caisson foundation structure and construction method for a deep-water sea-crossing bridge exceeding 100 meters

Abstract

The present invention discloses a caisson foundation structure and construction method for a deep-water sea-crossing bridge exceeding 100 meters. The caisson foundation structure is arranged in a stepped pattern, with its area gradually decreasing from bottom to top. The bottom area of the caisson foundation structure is determined based on the load of the bridge superstructure, and the top area of the caisson foundation structure is set to be larger than the bridge pier area. This invention utilizes the rotation of the caisson foundation, combined with the requirement for water injection before the caisson foundation is planted, to achieve a transition from a light draft to a heavy draft foundation structure, thereby avoiding the problems of building ultra-deep docks and dredging overly deep waterways.

Description

Technical Field

[0001] The present invention relates to the field of deep-water bridge foundations, and more specifically, to a caisson foundation structure and construction method for a super-100-meter deep-water sea-crossing bridge. Background Art

[0002] As China's infrastructure continues to improve, more and more world-class bridges are emerging. These bridges are gradually expanding from inland waterways to the ocean, such as the Hong Kong-Zhuhai-Macao Bridge, the Hangzhou Bay Bridge, and the China-Malaysia Friendship Bridge. A prominent feature of cross-sea bridge construction is excessive water depth, making traditional pile foundation designs difficult to construct. Excessive water depth results in excessively long pile foundation cantilevers, making it difficult to meet construction precision requirements and posing safety risks. Furthermore, the main spans of cross-sea bridges are typically located far from land, making it difficult to transport cast-in-place concrete over long distances. Caisson foundations are widely used in overseas bridge foundation construction. They can be prefabricated in a factory, transported to the bridge site by tugboat, and lowered, enabling rapid foundation construction. However, these caisson structures are heavy and require deep docks and waterways to ensure smooth floating. This often makes them unsuitable for structures with maximum water depths of approximately 100 meters in the Qiongzhou Strait and 300 meters in the Strait of Gibraltar. In summary, it is necessary to study a deep-water foundation structure and construction method for bridges that can adapt to water depths exceeding 100 meters. Summary of the Invention

[0003] The purpose of the present invention is to provide a caisson foundation structure and construction method for a super-100-meter deep-water cross-sea bridge. By utilizing the rotation of the caisson foundation and combining it with the characteristic that the caisson foundation needs to be injected with water before being implanted, the foundation structure form can be transformed from a light draft to a heavy draft, thereby avoiding the problems of building ultra-deep docks and dredging over-deep channels.

[0004] In order to achieve these purposes and other advantages according to the present invention, a caisson foundation structure for a deep-water cross-sea bridge exceeding 100 meters is provided. The area of the caisson foundation structure gradually decreases from bottom to top and is arranged in a stepped manner. The bottom area of the caisson foundation structure is determined according to the load of the bridge superstructure, and the top area of the caisson foundation structure is set to be larger than the area of the bridge pier.

[0005] Preferably, the caisson foundation structure is a steel-concrete structure.

[0006] Preferably, the caisson foundation structure is an axisymmetric structure.

[0007] Preferably, the caisson foundation structure needs to be divided into compartments in the height direction, and each compartment must be ensured to be watertight.

[0008] Preferably, each step of the caisson foundation structure is round-end shaped or cylindrical.

[0009] Preferably, the caisson foundation structure is provided with a water injection hole.

[0010] The present invention also provides a construction method for a caisson foundation structure of a super-100-meter deep-water sea-crossing bridge, comprising the following steps:

[0011] Step 1: The caisson foundation structure is prefabricated in the dock, with the surface with the largest projected surface area among the six surfaces of the caisson foundation structure being prefabricated as the contact surface with the ground;

[0012] Step 2: Fill the dock with water, and after filling, the caisson foundation structure will be floated up by the buoyancy of the water;

[0013] Step 3: Use a tugboat to tow the caisson foundation structure from the shallow water area to the deep water area;

[0014] Step 4: Secure the caisson foundation structure at the deep-water foundation bridge site by anchoring it so that the caisson foundation structure can sway with the waves at the deep-water foundation bridge site, but will not deviate from the construction range under the operation of wind, water flow and second-order wave forces;

[0015] Step 5: Fill the caisson foundation structure with water, compartment by compartment, from the bottom of the caisson foundation structure to the designed compartment. During the water filling process, the caisson foundation structure will tilt under the eccentric effect of the water weight. When the water filling volume is sufficient, the caisson foundation structure will change from horizontal to vertical.

[0016] Step 6: After the caisson foundation structure is vertical, the caisson foundation structure has a large draft but has not yet been planted. Tighten the anchor system of the caisson foundation structure to strengthen the constraint on the movement of the caisson foundation structure, continue to add water or sand to the caisson foundation structure, and carry out positioning and final sinking.

[0017] Preferably, in step one, the caisson foundation structure is prefabricated in the dock. When the designed water depth of the dock is too small or the water depth of the channel is too small, a part of the caisson foundation structure is prefabricated in the dock, and the remaining part is prefabricated in deep water at sea with certain wave protection.

[0018] Preferably, when there is no dock near the bridge site, a suitable site can be selected, slope excavation can be carried out, foundation reinforcement can be carried out, precipitation can be carried out, a temporary dock can be formed, and the caisson foundation structure can be prefabricated.

[0019] Preferably, the anchor system is a gravity anchor.

[0020] The present invention has at least the following beneficial effects:

[0021] 1. It avoids the construction of ultra-deep docks, avoids excessive dredging of waterways, and reduces project costs.

[0022] 2. The larger waterline area during floating increases the stability of the large caisson during floating and ensures construction safety.

[0023] 3. The use of stepped round-end caissons reduces the force of water flow and waves, reduces seabed scouring, and makes engineering design and construction easier.

[0024] Fourth, the caisson is divided into compartments in the height direction, which better draws on the characteristics of ship engineering, innovates the structural form and construction method, and makes the construction of cross-sea bridges with a water depth of over 100 meters feasible.

[0025] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the caisson foundation structure design for a super-100-meter deep-water sea-crossing bridge according to the present invention;

[0027] Figure 2 It is a schematic diagram of the caisson foundation structure of the present invention after prefabrication and floating;

[0028] Figure 3 This is a schematic diagram of the caisson's posture during the water injection and rotation process of the present invention;

[0029] Figure 4 It is a schematic diagram of the posture of the caisson foundation structure after implantation of the present invention.

[0030] Explanation of reference numerals: 1 implantation water inlet, 2 subdivision watertight plate, 3 swivel water inlet, 4 waterline surface, 5 seabed surface. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0032] In the description of the present invention, the terms "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0033] The caisson foundation structure of the present application is particularly suitable for large caissons, and can also be applied to small caissons. A large caisson refers to a caisson with a maximum side length greater than 50m.

[0034] like Figure 1As shown, a caisson foundation structure for a deep-water sea-crossing bridge exceeding 100 meters is provided. The area of the caisson foundation structure gradually decreases from bottom to top, and is arranged in a stepped manner. The bottom area of the caisson foundation structure is determined according to the load of the bridge superstructure, and the top area of the caisson foundation structure is set to be larger than the area of the bridge pier body. More preferably, the top area of the caisson foundation structure is slightly larger than the area of the bridge pier body, thereby reducing the water flow force and wave force borne by the caisson foundation structure, reducing the local scouring caused by the giant caisson foundation structure, and alleviating the positioning error of the caisson foundation structure.

[0035] In another embodiment of the caisson foundation structure of the over-100-meter deep-water cross-sea bridge, the caisson foundation structure is a steel-concrete structure, thereby reducing material costs, ensuring better anti-corrosion performance, and providing good structural strength.

[0036] In another embodiment of the caisson foundation structure for a super-100-meter deep-water cross-sea bridge, the caisson foundation structure is an axisymmetric structure, thereby reducing the difficulty of rotation during construction.

[0037] In another embodiment of the caisson foundation structure of a super-100-meter deep-water cross-sea bridge, the caisson foundation structure is divided into compartments in the height direction by watertight panels, and each compartment is ensured to be watertight, thereby achieving the center of gravity adjustment in the height direction of the caisson, thereby achieving the smooth rotation of the caisson structure.

[0038] In another embodiment of the caisson foundation structure for a super-100-meter deep-water cross-sea bridge, each step of the caisson foundation structure is rounded or cylindrical, with the rounded ends being semicircular at both ends and rectangular in the middle. This is because the water flow force of the caisson foundation structure with rounded or cylindrical steps is about 1 / 4 of that of a rectangular caisson, thereby reducing the difficulty of positioning the caisson foundation structure. Figure 1 As shown, the top compartment of the caisson foundation structure is set as a cylindrical structure, and the remaining compartments are set as round-end structures.

[0039] In another embodiment of the caisson foundation structure of the super 100-meter deep-water cross-sea bridge, the caisson foundation structure is provided with water injection holes, and the water injection holes include a bed water inlet and a rotation water inlet. Figure 1 As shown, a bed water inlet is provided on the top of the top compartment of the caisson foundation structure, and a rotation water inlet is provided on the sides of the remaining compartments of the caisson foundation structure.

[0040] like Figures 2-4 As shown, a construction method for a caisson foundation structure of a super-100-meter deep-water cross-sea bridge comprises the following steps:

[0041] Step 1: The caisson foundation structure is prefabricated within the dock. The surface with the largest projected surface area among the six surfaces of the caisson foundation structure serves as the contact surface with the ground. If the dock's design water depth is too shallow or the channel depth is too shallow, a portion of the caisson foundation structure is prefabricated within the dock, and the remaining portion is prefabricated in deeper water at sea with adequate wave protection. If there is no dock near the bridge site, a suitable site can be selected, sloped, excavated, and foundation reinforced to reduce water levels. This creates a temporary dock, where the caisson foundation structure can be prefabricated.

[0042] Step 2: Fill the dock with water. After filling, the caisson foundation structure will be floated up by the buoyancy of the water. The caisson foundation structure on this side has a large area and a small draft, which can generally be controlled within 15m. Figure 2 Shown is the floating of the caisson foundation structure after prefabrication and a schematic diagram of the waterline.

[0043] Step 3: Use a tugboat to float the caisson foundation structure from the shallow water area to the deep water area.

[0044] Step 4: Secure the caisson foundation structure at the deepwater foundation bridge site by anchoring it. This allows the caisson foundation structure to sway with the waves at the deepwater foundation bridge site, but will not deviate from the construction range under wind, current, and second-order wave forces. The anchor system is a concrete gravity anchor, but large-tonnage, high-holding force anchors or other structural forms are also possible.

[0045] Step 5: Fill the caisson foundation structure with water, compartment by compartment, from the bottom of the caisson foundation structure to the designed compartment. During the water filling process, the caisson foundation structure will tilt under the eccentric effect of the water weight. When the water filling volume is sufficient, the caisson foundation structure will change from horizontal to vertical. It should be noted that during the rotation process, the caisson structure is subject to a certain eccentric load. The rigidity of the caisson foundation structure must be guaranteed based on the specific force. If the rigidity of the structure cannot be guaranteed, a certain support structure must be installed on the caisson foundation structure to ensure the rigidity of the structure. The support structure can be a rigid structure such as vertical reinforcing steel ribs, steel plates, and profiles.

[0046] Step 6. After the caisson foundation structure is vertical, the caisson foundation structure has a large draft but has not yet been planted. Tighten the anchor system of the caisson foundation structure to strengthen the constraint on the movement of the caisson foundation structure. Continue to add water or sand to the caisson foundation structure to perform positioning and final sinking, so that the bottom of the caisson foundation structure is planted and lands on the seabed. At this time, the planting water inlet at the top of the caisson foundation is still above the waterline.

[0047] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A construction method for a caisson foundation structure of a super-100-meter deep-water cross-sea bridge, characterized in that: The caisson foundation structure is arranged in a stepped manner from bottom to top, with its bottom area determined according to the load of the bridge superstructure and its top area being larger than the bridge pier area; The caisson foundation structure is a steel-concrete structure; it is axially symmetrical, its height direction is divided into compartments and each compartment is watertight, and the steps are round-end or cylindrical and are provided with water injection holes; The construction steps include: Step 1: prefabricate the surface with the largest projected surface area among the six surfaces of the caisson foundation structure in the dock as the contact surface; Step 2: After the dock is filled with water, the caisson foundation structure is floated by buoyancy; Step 3: Float the vessel to a deep-water area; Step 4: Anchor the caisson foundation structure, allowing it to sway with the waves but limiting its deviation from the construction area; Step 5: Fill the caisson compartments one by one with water from the bottom of the foundation structure to the designed compartments, and use the eccentric weight of the water to turn the caisson from a horizontal tilt to a vertical state; Step 6: When the caisson foundation structure is not planted after being vertical, tighten the anchor system of the caisson foundation structure and continue to add water or sand to the caisson foundation structure to complete the final positioning and sinking.

2. The construction method of the caisson foundation structure of the super-100-meter deep-water cross-sea bridge according to claim 1 is characterized in that: In the step 1, the caisson foundation structure is prefabricated in the dock. When the dock design water depth is too small or the channel water depth is too small, a part of the caisson foundation structure is prefabricated in the dock, and the remaining part is prefabricated in deep water at sea with certain wave protection.

3. The construction method of the caisson foundation structure of the super-100-meter deep-water cross-sea bridge according to claim 1 is characterized in that: When there is no dock near the bridge site, a suitable site can be selected, slope excavation can be carried out, foundation reinforcement can be carried out, precipitation can be carried out, a temporary dock can be formed, and the caisson foundation structure can be prefabricated.

4. The construction method of the caisson foundation structure of the super-100-meter deep-water cross-sea bridge according to claim 1 is characterized in that: The anchor system is a gravity anchor.

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