Caisson type cofferdam for open sea deepwater island building foundation construction

Abstract

The invention discloses a caisson type cofferdam for open sea deepwater island building foundation construction. The caisson type cofferdam comprises a plurality of caisson modules used for defining the cofferdam and blocking steel plates used for blocking gaps between the adjacent caisson modules. Each caisson module comprises a plurality of concrete caissons which are sequentially implanted on the seabed foundation and a plurality of cast-in-situ bored piles for connecting the plurality of concrete caissons into a whole in the water depth direction; the four corners of a bottom plate of each concrete caisson are each provided with a shear groove, the four corners of a top plate of each concrete caisson are each provided with a shear key, and the concrete caissons are stacked in the mode that the shear keys and the shear grooves are mutually embedded. A plurality of pile holes penetrating from the top plate to the bottom plate are uniformly distributed in each concrete caisson; the blocking steel plates are fixed between the inner side faces and the outer side faces of every two adjacent caisson modules through bolts. The supporting and limiting strength of the whole cofferdam structure can be improved, the deformation phenomenon of the independent section of the cofferdam is avoided, and meanwhile the water seepage phenomenon is avoided when the cofferdam is used.

Description

Technical Field

[0001] This invention relates to a caisson cofferdam for foundation construction of deep-water islands in the open sea. Background Technology

[0002] With the increasing number of offshore artificial island reclamation projects, deep-water foundations bear the weight of the superstructure, control the shape of the artificial island, and withstand enormous lateral loads. Deep-water foundation construction typically employs cofferdam construction to obtain a dry construction environment. Common types of cofferdams include: Sheet pile cofferdams: They are quick to construct and reusable, and are economical when the water depth is not great. They are only suitable for sites with a water depth of 3-10m and require a construction environment with small waves, low flow velocity, and small water level fluctuations. They are more suitable for soil layers with low permeability, such as clay, silty clay, and sand. Double-walled steel cofferdam: mostly used for large deep-water foundations, it consists of a box-shaped structure made of double-layered steel plates, with concrete or water poured inside. It has high stability and can withstand large water pressure. Locked steel pipe pile cofferdam: Locked steel pipe piles can also serve as a foundation pit system, reducing the size of the cofferdam and simplifying the excavation process; the backfill sand between the front and rear pipes forms a water-stopping system, which is reliable; it is suitable for open sea areas with a water depth of 5-40m, and the pile diameter and pile wall thickness can be increased when encountering deep water. Steel cylindrical cofferdams: The water depth range of steel cylindrical cofferdams is generally 5-20m. The flow velocity and waves should not be too large. They are suitable for easily penetrable strata such as sand, clay, and silt. When encountering deep silt layers, the driving depth needs to be increased or foundation reinforcement needs to be adopted. The bearing layer of the foundation must have sufficient bearing capacity to prevent the cylinder from sinking or tilting. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a caisson cofferdam for the foundation construction of deep-water islands in the open sea. It can improve the support and limiting strength of the entire cofferdam structure, avoid deformation of individual sections of the cofferdam, and prevent water seepage during the use of the cofferdam.

[0004] The objective of this invention is achieved as follows: a caisson cofferdam for foundation construction of deep-water islands in the open sea, comprising multiple caisson modules for forming the cofferdam and sealing steel plates for sealing the gaps between adjacent caisson modules; Each caisson module comprises several concrete caissons stacked sequentially on a seabed foundation and several bored piles connecting the concrete caissons into a single unit across the water depth; among which, The concrete caisson is a rectangular box. Each of the four corners of the bottom plate of the concrete caisson is provided with a shear groove, and each of the four corners of the top plate of the concrete caisson is provided with a shear key corresponding to the four shear grooves. Several pile holes are evenly distributed inside the concrete caisson, extending from the top plate to the bottom plate. Several concrete caissons are stacked in a manner in which the shear keys and shear grooves are interlocked. Several bored piles are installed in several pile holes in a one-to-one correspondence; each bored pile is composed of a subsea pile segment, several upper pile segments, and a top pile segment; the subsea pile segment is formed by pouring concrete into the pile hole at a set depth in the concrete caisson at the bottom of the seabed foundation to the middle of the pile hole height; each upper pile segment is formed by pouring concrete into the pile hole at the middle of the pile hole height in the next concrete caisson segment to the middle of the pile hole height in the previous concrete caisson segment; the top pile segment is formed by pouring concrete into the pile hole at the middle of the pile hole height in the next top concrete caisson segment to the top of the pile hole in the previous concrete caisson segment. The sealing steel plate is fixed between the inner sides of two adjacent caisson modules and between the outer sides of two adjacent caisson modules by multiple pairs of bolts.

[0005] The aforementioned caisson cofferdam used for deep-water island construction foundations in the open sea includes a water injection hole on the top plate of each concrete caisson, and each concrete caisson is divided into several compartments by longitudinal and transverse partitions, with water passage holes on each longitudinal and transverse partition.

[0006] In the aforementioned caisson cofferdam used for deep-water island construction foundations in the open sea, the seabed foundation on which the caisson module is placed is reinforced with sand piles.

[0007] The aforementioned caisson cofferdam used for deep-water island construction foundations in the open sea has a crushed stone leveling layer on the surface of the seabed foundation after sand pile reinforcement.

[0008] The features of the caisson cofferdam for deep-water island construction foundations in the open sea of ​​the present invention are: 1. The concrete caissons used in this invention are connected vertically (in the water depth direction) into caisson modules via shear keys and shear grooves. The caisson modules are then connected to the reinforced seabed foundation via bored concrete piles to form a whole. The gaps between adjacent caisson modules are sealed with sealing steel plates. Force can be transferred between the concrete caissons, resulting in uniform stress distribution. This improves the support and limiting strength of the entire cofferdam structure, prevents deformation of individual sections of the cofferdam, and avoids water seepage during the use of the cofferdam.

[0009] 2. The shear key and shear groove fitting connection used in this invention can realize the positioning of the upper and lower concrete caissons during the installation of the caisson module, effectively avoiding the problem of difficult control of underwater construction accuracy, reducing the amount of underwater on-site construction, and ensuring the vertical connection effect of the cofferdam structure.

[0010] 3. The concrete bored piles used in this invention can effectively connect the caisson module to the seabed foundation, avoiding the deformation of the cofferdam caused by the huge lateral force generated by the internal and external pressure difference. This makes the entire cofferdam construction operation simple and convenient, and allows for flexible installation of the concrete caisson, resulting in high construction efficiency.

[0011] 4. The present invention employs sand pile reinforcement and seabed gravel leveling layer treatment for the seabed foundation, which can effectively ensure the connection between the concrete caisson and the seabed foundation, increase the vertical and lateral bearing capacity of the cofferdam, and effectively transfer the load to the seabed foundation. Attached Figure Description

[0012] Figure 1 This is a plan view of the caisson cofferdam used for foundation construction of deep-water islands in the open sea according to the present invention; Figure 2 This is a partial plan view of the caisson cofferdam used for foundation construction of deep-water islands in the open sea according to the present invention; Figure 3 yes Figure 2 AA direction view; Figure 4 This is a plan view of the concrete caisson constituting the caisson module in the caisson-type cofferdam for the foundation construction of deep-sea islands in the offshore area according to the present invention. Figure 5 yes Figure 4 BB view in the middle. Detailed Implementation

[0013] The invention will now be further described with reference to the accompanying drawings.

[0014] Please see Figures 1 to 5 The caisson cofferdam for deep-water island construction foundation construction in the open sea of ​​the present invention includes multiple caisson modules 1 for forming a cofferdam and sealing steel plates 3 for sealing the gaps between adjacent caisson modules 1.

[0015] Each caisson module 1 includes several concrete caissons 10 stacked sequentially on the seabed foundation and several bored piles 2 connecting the concrete caissons 10 into a whole in the water depth direction; wherein, The seabed foundation of the caisson module 1 is reinforced with sand piles 4, and a gravel leveling layer 5 is provided on the surface of the seabed foundation after reinforcement. The concrete caisson 10 is a rectangular box. Each of the four corners of the top plate of the concrete caisson 10 is provided with a shear key 11a, and each of the four corners of the bottom plate of the concrete caisson 10 is provided with a shear groove 11b corresponding to the four shear keys 11a. Four pile holes 12 are evenly distributed inside the concrete caisson 10, extending from the top plate to the bottom plate. Each concrete caisson 10 is also provided with a water injection hole 13 in the top plate. Each concrete caisson 10 is divided into several compartments by longitudinal and transverse partitions 14, and each longitudinal and transverse partition 14 is provided with a water passage hole 15. Several concrete caissons 10 are stacked in a manner in which the shear keys 11a and the shear grooves 11b are interlocked. Four bored piles 2 are installed in four pile holes 12 in a one-to-one correspondence; the number of bored piles 2 is calculated based on the actual stress conditions of the caisson module 1. Each bored pile 2 is spliced ​​together from a seabed pile section, several upper pile sections, and a top pile section; the seabed pile section is formed by pouring concrete into the pile hole 12 at the bottom of the concrete caisson 10 at a set depth on the seabed foundation; each upper pile section is formed by pouring concrete into the pile hole 12 at the middle of the height of the next concrete caisson 10 to the middle of the height of the pile hole 12 in the previous concrete caisson 10; the top pile section is formed by pouring concrete into the pile hole 12 at the middle of the height of the next uppermost concrete caisson 10 to the top of the pile hole 12 in the topmost concrete caisson 10.

[0016] The sealing steel plate 3 is fixed between the inner sides of two adjacent caisson modules 1 and between the outer sides of two adjacent caisson modules 1 by multiple pairs of bolts 30.

[0017] The caisson-type cofferdam for deep-water island construction foundation construction of the present invention can realize the overall stress of the cofferdam and the seabed foundation reinforced by sand piles, and can resist the lateral force of the caisson-type cofferdam through concrete cast-in-place piles 2, which is beneficial to sand dredging and reclamation operations and improves construction efficiency.

[0018] The caisson cofferdam for deep-water island construction foundations of the present invention includes the following steps during construction: S1. First, the seabed foundation where the cofferdam is placed is reinforced with sand piles 4. The width of the treated seabed foundation is greater than the width of the caisson module 1. Then, a gravel leveling layer 5 is laid on the surface of the reinforced seabed foundation. S2. First, the bottom section of the concrete caisson 10 is sank by injecting water through the water injection hole 13 until the bottom section of the concrete caisson 10 lands on the crushed stone leveling layer 5. Then, the bottom section of the concrete caisson 10 is drilled into the seabed foundation through the pile hole 12 to the set depth to form a seabed pile hole. Concrete is then poured into the seabed pile hole until the concrete is poured to the middle of the height of the pile hole 12 of the bottom section of the concrete caisson 10, forming a seabed pile segment. S3. The next concrete caisson 10 is lowered to the top of the previous concrete caisson 10 by injecting water through the water injection hole 13. It is then stacked on the top plate of the previous concrete caisson 10 by cooperating with the shear groove 11b on the next concrete caisson 10 and the shear key 11a on the previous concrete caisson 10, so that the four pile holes 12 in the next concrete caisson 10 are aligned with the four pile holes 12 in the previous concrete caisson 10. Concrete is then poured into each pile hole 12 until the concrete reaches the middle of the height of each pile hole 12 in the next concrete caisson 10, forming the upper pile segment. S4. The top section of concrete caisson 10 is sunk to the top of the previous section of concrete caisson 10 by injecting water through the water injection hole 13. The top section of concrete caisson 10 is then placed on the top plate of the previous section of concrete caisson 10 by fitting the shear groove 11b on the top section of concrete caisson 10 and the shear key 11a on the previous section of concrete caisson 10. This aligns the four pile holes 12 in the top section of concrete caisson 10 with the four pile holes 12 in the previous section of concrete caisson 10. Concrete is then poured into each pile hole 12 until the concrete reaches the top of each pile hole 12 in the top section of concrete caisson 10, forming the top pile segment and four bored piles 2. S6. Repeat steps S2 to S5 until all caisson modules 1 are constructed. Then, use sealing steel plates 3 to fix the inner sides of two adjacent caisson modules 1 and the outer sides of two adjacent caisson modules 1 with multiple pairs of bolts to form a waterproof structure between two adjacent caisson modules 1, thereby achieving leak sealing and forming a relatively fixed overall structure in the longitudinal direction of multiple caisson modules 1.

[0019] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A caisson cofferdam for foundation construction of deep-water islands in the open sea, comprising multiple caisson modules for forming the cofferdam and sealing steel plates for sealing the gaps between adjacent caisson modules, characterized in that, Each caisson module comprises several concrete caissons stacked sequentially on a seabed foundation and several bored piles connecting the concrete caissons into a single unit across the water depth; among which, The concrete caisson is a rectangular box. Each of the four corners of the bottom plate of the concrete caisson is provided with a shear groove, and each of the four corners of the top plate of the concrete caisson is provided with a shear key corresponding to the four shear grooves. Several pile holes are evenly distributed inside the concrete caisson, extending from the top plate to the bottom plate. Several concrete caissons are stacked in a manner in which the shear keys and shear grooves are interlocked. Several bored piles are installed in several pile holes in a one-to-one correspondence; each bored pile is composed of a subsea pile segment, several upper pile segments, and a top pile segment; the subsea pile segment is formed by pouring concrete into the pile hole at a set depth in the concrete caisson at the bottom of the seabed foundation to the middle of the pile hole height; each upper pile segment is formed by pouring concrete into the pile hole at the middle of the pile hole height in the next concrete caisson segment to the middle of the pile hole height in the previous concrete caisson segment; the top pile segment is formed by pouring concrete into the pile hole at the middle of the pile hole height in the next top concrete caisson segment to the top of the pile hole in the previous concrete caisson segment. The sealing steel plate is fixed between the inner sides of two adjacent caisson modules and between the outer sides of two adjacent caisson modules by multiple pairs of bolts.

2. The caisson cofferdam for foundation construction of deep-water islands in offshore areas according to claim 1, characterized in that, Each concrete caisson has a water injection hole on its top slab. Each concrete caisson is divided into several compartments by longitudinal and transverse partitions, and each longitudinal and transverse partition has a water passage hole.

3. The caisson cofferdam for foundation construction of deep-water islands in offshore areas according to claim 1, characterized in that, The seabed foundation upon which the caisson module lands is reinforced using sand piles.

4. The caisson cofferdam for deep-water island construction foundations in offshore areas according to claim 3, characterized in that, The surface of the seabed foundation, after being reinforced by sand piles, is provided with a gravel leveling layer.

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