A caisson shipping wharf system, construction method and design method

Abstract

The present application relates to the wharf construction technical field, especially to a caisson delivery wharf system, construction method and design method. The caisson delivery wharf system comprises: a wharf platform, which extends the coastline on the sea side; at least two foundation piles, the upper end of the foundation pile is embedded in the wharf platform, and the foundation pile is a steel pipe pile; a steel sheet pile, which is arranged on the land side of the wharf platform, the lower part of the steel sheet pile is embedded and arranged, and the upper part of the steel sheet pile is stacked with blocks away from the side of the wharf platform. The caisson delivery wharf system provided by the present application can be quickly built into shape and has a large carrying capacity. The steel pipe pile is used as the main vertical support component of the wharf platform, which can realize a large carrying capacity at a low cost, meet the carrying and delivery needs of large structures such as caisson, and the steel sheet pile is arranged on the land side of the wharf platform, which can realize a large lateral carrying capacity of the wharf platform at a low cost. The steel pipe pile and the steel sheet pile are convenient to remove, which can reduce the removal cost and thus reduce the caisson delivery cost.

Description

Technical Field

[0001] This invention relates to the field of wharf construction technology, and in particular to a caisson transport wharf system, construction method, and design method. Background Technology

[0002] The construction of gravity-type wharves typically includes the following steps: fabricating caissons in the prefabrication yard; moving the caissons to the designed location on the shore; and constructing the superstructure of the caissons. Among these steps, moving the caissons to the designed location on the shore often involves transporting them by work barges. The specific operations include: moving the caissons from the prefabrication yard to the shore departure wharf; loading the caissons from the departure wharf onto the work barges; and transporting and lowering the caissons by the work barges.

[0003] In actual construction, technicians found that in most construction plans, the shipping dock is a temporary facility that will be dismantled after the caisson is shipped. If it is built with cast-in-place piles to the standard of a permanent facility, the shipping cost will be greatly increased and the dismantling after shipping will be troublesome. If it is built to the standard of a temporary facility, the existing temporary dock is not able to support the huge weight of the caisson. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a caisson transport terminal system, construction method and design method, which has the advantages of low construction cost, large load-bearing capacity and convenient dismantling.

[0005] In a first aspect, the present invention provides a caisson shipping terminal system, comprising:

[0006] The dock platform has a land-facing side and a sea-facing side that are set opposite to each other, with the sea-facing side extending out of the coastline;

[0007] At least two foundation piles support the wharf platform, the upper ends of the foundation piles are embedded in the wharf platform, and the foundation piles are steel pipe piles;

[0008] Sheet piles are installed on the landward side of the wharf platform. The lower part of the sheet piles is embedded, and the upper part of the sheet piles is piled with boulders on the side away from the wharf platform.

[0009] This invention provides a caisson transport wharf system that can be quickly constructed and has a large load-bearing capacity, facilitating the transport of caissons. It employs steel pipe piles as the main vertical support components of the wharf platform. Steel pipe piles are characterized by convenient installation, fast construction speed, and high load-bearing capacity, achieving a large load-bearing capacity at a relatively low cost, meeting the load-bearing and transport needs of large structures such as caissons. Steel sheet piles are installed on the land-facing side of the wharf platform, with the sheet piles firmly embedded, and boulders are piled on the other side, enabling a large lateral load-bearing capacity of the wharf platform at a relatively low cost. The steel pipe piles and steel sheet piles are easy to dismantle, reducing dismantling costs and thus lowering the cost of transporting caissons.

[0010] As a preferred embodiment of the present invention, it further includes an outbound channel connecting the wharf platform, wherein a transitional boulders layer is provided at the connection between the outbound channel and the wharf platform, the surface layer of the outbound channel and the wharf platform are both attached to the transitional boulders layer, and the transitional boulders layer is filled with boulders.

[0011] The transition riprap layer is filled with riprap, which has high hardness and low settlement. The transition riprap layer can reduce the settlement at the connection between the wharf platform and the transport channel, so that large structures such as caissons can be transported smoothly to the wharf platform.

[0012] As a preferred embodiment of the present invention, the surface layer of the outbound channel is inclined, and the wharf platform is located at the lower end of the inclination; a crushed stone cushion layer is provided between the wharf platform and the transition boulders layer below it, and the crushed stone cushion layer is filled with crushed stone; the upper part of the steel sheet pile is embedded in the transition boulders layer.

[0013] As a preferred embodiment of the present invention, the foundation piles are arranged in rows along the offshore direction, and the row of foundation piles closest to the seaside side is densely arranged.

[0014] The row of foundation piles closest to the seaside is densely arranged. This dense arrangement can improve the vertical and lateral load-bearing capacity of the wharf platform on the seaside side. By improving the vertical load-bearing capacity, the wharf platform can meet the needs of semi-submersible barge connection, which is convenient for transporting caissons by semi-submersible barges. By improving the lateral load-bearing capacity, it can meet the needs of ship mooring and collision protection of the wharf platform.

[0015] As a preferred embodiment of the present invention, a sloping surface is provided below the wharf platform, and the surface of the sloping surface is provided with a riprap revetment; at least a portion of the foundation piles penetrate the riprap revetment.

[0016] As a preferred embodiment of the present invention, a semi-submersible barge connection platform is provided on the seaward side of the wharf platform, and the upper surface of the semi-submersible barge connection platform is lower than the upper surface of the wharf platform.

[0017] By setting up a semi-submersible barge connection platform, it is easy to connect and fix the semi-submersible barge, thus facilitating the transportation of large structures such as caissons onto the semi-submersible barge.

[0018] As a preferred embodiment of the present invention, the upper surface of the semi-submersible barge bridging platform is provided with a supporting steel plate; the side wall of the wharf platform facing the sea is provided with a rubber pad, which is located above the semi-submersible barge bridging platform; the wharf platform and the semi-submersible barge bridging platform are integrally formed.

[0019] As a preferred embodiment of the present invention, the dock platform is provided with mooring bollards; the dock platform is thickened at the position near the semi-submersible barge connecting platform.

[0020] In a second aspect, the present invention provides a construction method for a caisson transport terminal system as described above, comprising the following steps:

[0021] S1. Drive the foundation piles, which are steel pipe piles, into the designed location;

[0022] Excavate a transition trench, which is located on the landward side of the designed location of the wharf platform;

[0023] The steel sheet piles are driven into the transition groove, and rubble is laid on both sides of the steel sheet piles.

[0024] S2. The wharf platform is cast in place, with the top of the foundation piles embedded in the bottom of the wharf platform, and the land-facing side of the wharf platform abutting the steel sheet piles.

[0025] In a third aspect, the present invention provides a design method for a caisson shipping terminal system as described above, comprising the following steps:

[0026] A1. Determine the maximum load-bearing capacity of the wharf platform based on the caisson;

[0027] A2. Determine the structure of the wharf platform based on its maximum load-bearing capacity;

[0028] A3. Determine the self-weight of the wharf platform based on its structure;

[0029] A4. Based on the maximum load-bearing capacity of the wharf platform, the self-weight of the wharf platform, the overlapping load, the mooring force, the horizontal force of the caisson being pulled onto the barge, and the earth pressure exerted on the wharf platform by the riprap retaining wall of the caisson transport channel, load combinations are performed.

[0030] A5. Construct a design model for the caisson transport terminal system based on the aforementioned terminal platform structure and load combination structure;

[0031] A6. Based on the design model of the caisson shipping terminal system, calculate whether the strength and stiffness of the steel pipe piles meet the design requirements. If not, modify the terminal platform structure in step A2 and repeat steps A3-A6 until the strength and stiffness of the steel pipe piles meet the design requirements and obtain a terminal platform structure that meets the design requirements.

[0032] A7. Based on the wharf platform structure that meets the design requirements, calculate the punching shear capacity of the slab without stirrups or bent-up bars under local loads or concentrated reaction forces, and whether the overall stability of the embankment slope meets the design requirements. If not, modify the wharf platform structure in step A2 and repeat steps A3-A6 until the strength and stiffness of the steel pipe piles meet the design requirements, and obtain a wharf platform structure that meets the design requirements.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This invention provides a caisson transport wharf system that can be quickly constructed and has a large load-bearing capacity, facilitating the transport of caissons. It employs steel pipe piles as the main vertical support components of the wharf platform. Steel pipe piles are characterized by convenient installation, fast construction speed, and high load-bearing capacity, achieving a large load-bearing capacity at a relatively low cost, meeting the load-bearing and transport needs of large structures such as caissons. Steel sheet piles are installed on the land-facing side of the wharf platform, with the sheet piles firmly embedded, and boulders are piled on the other side, enabling a large lateral load-bearing capacity of the wharf platform at a relatively low cost. The steel pipe piles and steel sheet piles are easy to dismantle, reducing dismantling costs and thus lowering the cost of transporting caissons. Attached Figure Description

[0035] Figure 1 This is a structural schematic diagram (side view) of the caisson shipping terminal system described in this invention;

[0036] Figure 2 for Figure 1 Enlarged view of section A in the middle;

[0037] Figure 3 for Figure 1 Enlarged view of section B in the middle;

[0038] Figure 4 This is a diagram showing the pile layout of the caisson transport terminal system described in this invention.

[0039] Figure 5 This is a structural schematic diagram (top view) of the caisson transport terminal system described in this invention;

[0040] Figure 6 This is a schematic diagram of the airbag distribution;

[0041] Figure 7 This is a schematic diagram for calculating airbag pressure.

[0042] Figure 8 This is a schematic diagram of the pile bottom reaction force when the caisson is located at the rear edge of wharf platform 1.

[0043] Figure 9 This is a schematic diagram of the pile bottom reaction force when the caisson is located in the middle of wharf platform 1.

[0044] Figure 10 This is a schematic diagram of the pile bottom reaction force when the caisson is located at the front edge of the wharf platform 1.

[0045] Figure 11 This is a stress distribution diagram during the strength verification of steel pipe piles;

[0046] Figure 12 The results are from the slope stability analysis.

[0047] Marked in the image:

[0048] 1- Dock platform;

[0049] 11-Foundation pile; 12-Sheet pile; 13-Crushed stone cushion layer; 14-Slope surface; 15-Rock facing; 16-Mooring bollard; 17-Landward side; 18-Seaward side;

[0050] 2-Outbound shipping channel;

[0051] 21-Transitional boulders layer; 22-Transitional groove;

[0052] 3- Semi-submersible barge connection platform;

[0053] 31-Supporting steel plate; 32-Rubber pad;

[0054] 4-Airbag. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0056] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0057] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0058] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing between identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0059] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0060] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0061] Example 1

[0062] Please see Figures 1 to 5 This embodiment provides a caisson transport terminal system, including a terminal platform 1 and at least two foundation piles 11. The foundation piles 11 support the terminal platform 1, and the upper end of the foundation piles 11 is embedded in the terminal platform 1. The foundation piles 11 are steel pipe piles. Steel sheet piles 12 are provided on the land-facing side 17 of the terminal platform 1. The lower part of the steel sheet piles 12 is embedded, and the upper part of the steel sheet piles 12 is piled with boulders on the side away from the terminal platform 1.

[0063] The wharf platform 1 is the superstructure of the shipping wharf. One side of the wharf platform 1 is connected to the caisson prefabrication yard, and the other side extends a certain distance from the coastline to ensure that there is sufficient water depth below this side to meet the draft requirements of the working barge. This extended side can be defined as the seaside side 18. The caisson can be moved from the prefabrication yard to the wharf platform 1 by airbags, and then further moved on the wharf platform 1 to the seaside side 18, from which it is loaded onto the barge.

[0064] The foundation pile 11 is connected to the lower part of the wharf platform 1 to support the wharf platform 1. The lower part of the foundation pile 11 is embedded in the rock or soil, and the self-weight of the wharf platform 1 and the upper load can be transferred downwards through the foundation pile 11. Figure 1 and Figure 5 As shown, several piles 11 are arranged in the transverse and longitudinal directions along the wharf platform 1, and some piles 11 are located on the outer side of the coastline, with the upper part of these piles 11 exposed to seawater.

[0065] To meet load-bearing requirements and facilitate subsequent dismantling, the foundation pile 11 in this embodiment is a steel pipe pile. Steel pipe piles have the advantages of fast construction speed, convenient underwater construction, and convenient dismantling. Moreover, the overall construction cost is relatively low. In terms of load-bearing capacity, the load-bearing capacity of steel pipe piles is close to that of cast-in-place piles used in permanent wharves, making them suitable for temporary shipping wharves.

[0066] To meet the stability requirements during caisson transport, in this embodiment, the upper end of the foundation pile 11 is embedded in the wharf platform 1, and steel sheet piles 12 are installed on the landward side 17 opposite the seaward side 18 of the wharf platform 1. On the side of the steel sheet piles 12 away from the wharf platform 1, boulders are piled up. The upper side of the steel sheet piles 12 abuts against the wharf platform 1, and the lower part is embedded in the soil or rock. Through the compression of the steel sheet piles 12 and the boulders, a large lateral force can be applied to the wharf platform 1, thereby greatly improving the lateral bearing capacity of the transport wharf.

[0067] Therefore, the caisson transport wharf system provided in this embodiment can be quickly constructed and has a large load-bearing capacity, which can be used for caisson transport. Steel pipe piles are used as the main vertical support components of the wharf platform 1. Steel pipe piles have the characteristics of convenient installation, fast construction speed and large load-bearing capacity, which can achieve a large load-bearing capacity at a low cost and meet the load-bearing and transport needs of large structures such as caissons. Steel sheet piles 12 are set on the land-facing side 17 of the wharf platform 1. The steel sheet piles 12 are embedded and fixed, and the other side is piled with boulders, which can achieve a large lateral load-bearing capacity of the wharf platform 1 at a low cost. The steel pipe piles and steel sheet piles 12 are easy to dismantle, which can reduce dismantling costs and thus reduce the cost of caisson transport.

[0068] In some embodiments, the caisson shipping terminal system also includes a shipping channel 2, which connects the caisson prefabrication yard and the terminal platform 1. A transition boulders layer 21 is provided below the intersection of the terminal platform 1 and the shipping channel 2. The surface layer of the shipping channel 2 and the terminal platform 1 are both connected to the transition boulders layer 21, which is filled with boulders.

[0069] The boulders have high hardness and low settlement. By setting a transition boulder layer 21 at the intersection, the settlement at the connection between the wharf platform 1 and the outbound channel 2 can be reduced. This helps to reduce the height difference between the surface of the wharf platform 1 and the surface of the outbound channel 2 during the caisson's passage, allowing the caisson to move more smoothly from the outbound channel 2 to the wharf platform 1.

[0070] Preferably, the upper part of the sheet pile 12 is embedded in the transition boulders layer 21. The transition boulders layer 21 can reduce the deformation of the sheet pile 12, thereby improving the lateral stiffness and stability of the wharf platform 1.

[0071] Preferably, the surface of the transport channel 2 is inclined, and the wharf platform 1 is located at the lower end of the inclination; the inclination facilitates the movement of the caisson, and the inclination slope can be selected from 1:55 to 1:65, and more preferably 1:60.

[0072] A gravel cushion layer 13 is also provided between the dock platform 1 and the transition stone layer 21 below it, and the gravel cushion layer 13 is filled with gravel.

[0073] In some embodiments, the piles 11 are arranged in rows along the offshore direction, and the row of piles 11 closest to the seaside side 18 is densely arranged.

[0074] The row of foundation piles 11 closest to the seaside side 18 is densely arranged. This dense arrangement can improve the vertical and lateral bearing capacity of the seaside side 18 of the wharf platform 1. By improving the vertical bearing capacity, the wharf platform 1 can meet the requirements for semi-submersible barge connection, which is convenient for transporting caissons by semi-submersible barge. By improving the lateral bearing capacity, it can meet the requirements for ship berthing and collision protection of the wharf platform 1.

[0075] Taking this embodiment as an example: five rows of foundation piles 11 are set along the offshore direction. The row closest to the seaside 18 has 8 foundation piles 11, and the other four rows each have 4 foundation piles 11.

[0076] In some embodiments, a sloping surface 14 is provided below the wharf platform 1, and a riprap revetment 15 is provided on the surface of the sloping surface 14; at least some of the foundation piles 11 penetrate the riprap revetment 15.

[0077] In some embodiments, a semi-submersible barge connection platform 3 is provided on the seaward side 18, and the upper surface of the semi-submersible barge connection platform 3 is lower than the upper surface of the dock platform 1.

[0078] By setting up a semi-submersible barge connection platform 3, it is easy to connect and fix the semi-submersible barge, thus facilitating the transportation of large structures such as caissons onto the semi-submersible barge.

[0079] Preferably, the dock platform 1 and the semi-submersible barge connection platform 3 are integrated. The upper surface of the semi-submersible barge connection platform 3 is provided with a supporting steel plate 31, and the side wall of the seaside side 18 of the dock platform 1 is provided with a rubber pad 32, which is located above the semi-submersible barge connection platform 3.

[0080] Preferably, the dock platform 1 is provided with a mooring bollard 16; the dock platform 1 is thickened at the position near the semi-submersible barge connecting platform 3.

[0081] Example 2

[0082] This embodiment provides a construction method for a caisson transport terminal system as described in Embodiment 1, comprising the following steps:

[0083] S1. Drive foundation pile 11 into the designed location. Foundation pile 11 is a steel pipe pile.

[0084] Excavate transition trench 22, which is located on the land-facing side 17 of the designed location of wharf platform 1, and the two slopes of transition trench 22 are sloped.

[0085] Steel sheet piles 12 are driven into the transition trench 22, and rubble is laid on both sides of the steel sheet piles 12.

[0086] S2. Cast-in-place wharf platform 1, the top of the foundation pile 11 is embedded in the bottom of the wharf platform 1, and the land-facing side 17 of the wharf platform 1 abuts against the steel sheet pile 12.

[0087] Example 3

[0088] This embodiment provides a design method for a caisson shipping terminal system as described in any one of claims 1-8, characterized by comprising the following steps:

[0089] A1. Determine the maximum load-bearing capacity of the wharf platform 1 based on the caisson;

[0090] A2. Determine the structure of the wharf platform 1 based on its maximum load-bearing capacity;

[0091] A3. Determine the self-weight of the wharf platform 1 based on its structure;

[0092] A4. Based on the maximum load-bearing capacity of the wharf platform 1, the self-weight of the wharf platform 1, the overlapping load, the mooring force, the horizontal force of the caisson being pulled onto the barge, and the earth pressure exerted on the wharf platform by the rubble retaining wall of the caisson transport channel, load combinations are made.

[0093] A5. Based on the structure and load combination structure of the wharf platform 1, construct a design model for the caisson transport wharf system;

[0094] A6. Based on the design model of the caisson shipping terminal system, calculate whether the strength and stiffness of the steel pipe piles meet the design requirements. If not, modify the structure of the terminal platform 1 in step A2 and repeat steps A3-A6 until the strength and stiffness of the steel pipe piles meet the design requirements and obtain the terminal platform 1 structure that meets the design requirements.

[0095] A7. Based on the wharf platform 1 structure that meets the design requirements, calculate the punching shear capacity of the slab without stirrups or bent-up bars under local loads or concentrated reaction forces, and whether the overall stability of the embankment slope meets the design requirements. If not, modify the wharf platform 1 structure in step A2 and repeat steps A3-A6 until the strength and stiffness of the steel pipe piles meet the design requirements, and obtain the wharf platform 1 structure that meets the design requirements.

[0096] The design method of the caisson transport wharf system described in this embodiment is based on the maximum load-bearing capacity of the wharf platform 1 to determine the structure of the wharf platform 1. Then, through the design model of the load combination component caisson transport wharf system, the design model can systematically guide the design of the wharf platform 1 and the steel pipe piles, and can reasonably determine the structure of the wharf platform 1 and the steel pipe piles to meet the load-bearing requirements, and provide a theoretical basis for reducing costs.

[0097] Taking a specific caisson transport project as an example:

[0098] The maximum load-bearing capacity of wharf platform 1 is the load when the caisson is completely positioned on wharf platform 1. Taking a caisson with a length (longitudinal direction) of 18.75m as an example, its weight is Qmax = 27770kN. It is transported using nine 16.75m (effective length) long airbags 4. Figure 6 As shown, the airbags 4 are arranged vertically along the longitudinal axis of the caisson. The working height of the airbags 4 is 350mm. At this time, the width of the pressure-bearing surface of a single airbag 4 is 1.021m. When the airbags 4 are switched during the transport process, the force is considered based on the force of 9 airbags 4.

[0099] During the longitudinal movement of the caisson onto the barge, the entire weight of the caisson acts on the airbag 4. The effective length of a single airbag 4 is 16.75m, and the width of the pressure-bearing surface is 1.021m. Considering the force of 9 airbags 4, the pressure of the bottom of the airbag 4 on the wharf platform 1 is: 27770÷(16.75×1.021×9)=180.42kPa.

[0100] The design scheme for transport channel 2 is as follows: a 5cm crushed stone cushion layer 13 is laid at the bottom, and a 20t road roller is used to compact the foundation and the crushed stone cushion layer 13. A 20cm thick layer of C25 plain concrete is poured on top. The shear bearing capacity of its inclined section can be determined by the following formula:

[0101]

[0102] In the formula:

[0103] V u - Design value of shear capacity (N);

[0104] γ d -Structural coefficient, set to 1.1;

[0105] β h - Cross-section height influence coefficient;

[0106] f t -Design value of axial tensile strength of concrete (N / mm^2);

[0107] b - Width of the rectangular section;

[0108] h0 - Effective height of the cross section.

[0109] Calculations show that the design value of the shear bearing capacity per unit width of the 200mm thick C25 plain concrete surface layer is Vu=228.6kN>180.42×1=180.42kN, and the shear bearing capacity meets the requirements.

[0110] The characteristic value of the bearing capacity of the foundation after treatment is ≥150 kPa. The bearing capacity verification should be performed according to the above standard; please refer to [link / reference]. Figure 7 :

[0111] The stress diffusion angle of the concrete and crushed stone cushion layer is calculated as 45°. The pressure of the foundation below the cushion layer is:

[0112] P = 180.42 × 1.021 ÷ 1.478 + 25 × 0.2 + 18 × 0.05 = 130.53 kPa < 150 kPa, the bearing capacity of the foundation meets the requirements.

[0113] Based on local geological and hydrological conditions, and taking into account the size and weight of the caissons on site, a suitable structural type for the wharf platform 1 was selected, aiming to minimize investment while ensuring structural compliance. The overall stability of the wharf and the bearing capacity of the piles 11 under the transport load were verified to ensure they met the requirements for caisson transport.

[0114] This project has two proposed schemes. Scheme 1 involves a 24m long and 27m wide structure along the shoreline, using a high-pile pier structure with a pier thickness of 1.5m. Five rows of φ1200mm (δ=18mm) steel pipe piles are installed along the width, with the pile tips bearing strongly weathered granite. The area beneath the wharf is excavated using a slope of 1:3. A row of JU600*210*18 steel sheet piles is driven behind the wharf, with the pile bottoms penetrating the silty clay interlayer. A retaining wall of 2.5-3.5t riprap is used.

[0115] Option 2 is as follows: The outbound wharf is 24m long and 27m wide along the shoreline, with a high-pile pier structure and a pier thickness of 1.5m. Five rows of φ1200mm cast-in-place piles are installed along the width, with the bearing layer at the pile tip being strongly weathered granite. The area below the wharf is excavated using a slope method with an excavation gradient of 1:3. A row of JU600*210*18 steel sheet piles is driven behind the wharf, with the pile bottom penetrating the silty clay interlayer. The area behind the steel sheet piles is backfilled with rubble as a retaining wall.

[0116] The advantages of Option 1 are: 1. Fast construction speed; 2. Easy demolition; 3. Lower project cost than Option 2. The disadvantages are: 1. The steel pipe piles have low rigidity, and the overall deformation of the wharf is greater than that of Option 2.

[0117] The advantages of Option 2 are: 1. Better wharf durability; 2. Greater overall structural rigidity and less deformation. The disadvantages are: 1. Slower construction speed of cast-in-place piles; 2. Difficult demolition; 3. Higher project cost than Option 1.

[0118] Based on comprehensive comparison and analysis, Option 1 is recommended for the wharf structure.

[0119] The wharf structure calculation mainly includes the wharf platform structure calculation and the slope stability verification. The main calculation results of the recommended scheme are as follows:

[0120] The Midascivil was used to perform structural calculations for dock platform 1.

[0121] (1) The pier thickness is 1.5m, and the material is C35;

[0122] (2) Piles 11 are φ1200 steel pipe piles with a wall thickness of 18mm, and are calculated as hinged at the top and fixed at the bottom.

[0123] (3) Calculation using the m method

[0124] The soil spring of pile 11 is calculated according to the m-method given in the foundation code: K = ab1mz.

[0125] In the formula: a—thickness of each soil layer;

[0126] b1—Calculated width of the pile;

[0127] m—proportional coefficient of foundation soil;

[0128] z—the distance from the midpoint of each soil layer to the ground surface.

[0129] The calculated width of the pile can be calculated using the following formula: when d ≥ 1.0m, b1 = k × k f ×(d+1) When d, b1=k×k f ×(1.5*d+0.5);

[0130] For single-row piles or multi-row piles with L1≥0.6h1, k=1.0;

[0131] For multiple rows of piles where L1 < 0.6h1, k = b2 + (1 - b2) / 0.6 × L1 / h1;

[0132] In the formula, b1 is the calculated width of the pile (m), and b1 ≤ 2d;

[0133] d—Pile diameter or width of the pile perpendicular to the direction of the horizontal external force (m);

[0134] k f —The pile shape conversion factor depends on the surface of the horizontal force (perpendicular to the direction of the horizontal force), for circular or circular end faces k f =0.9; rectangular cross-section k f =1.0; for the combined circular and rectangular cross-section k f = (1 - 0.1 * a / d);

[0135] k—the coefficient of mutual influence between piles, parallel to the direction of the horizontal force;

[0136] L1—the net distance between piles parallel to the direction of the horizontal force; when the piles are arranged in a quincunx pattern, if the center distance c between two adjacent rows of piles is less than (d+1)m, it can be calculated based on the projected distance between each pile on the surface of the horizontal force.

[0137] h1—Calculated embedment depth of piles below the ground or local scour line, which can be taken as h1=3×(d+1), but shall not be greater than the embedment depth h of piles below the ground or local scour line;

[0138] b2—A coefficient related to the number of piles n in a row of piles parallel to the direction of the horizontal force. When n=1, b2=1.0; when n=2, b2=0.6; when n=3, b2=0.5; when n=4, b2=0.45.

[0139] The design loads include:

[0140] The self-weight of the dock platform 1 includes the weight of the internal steel reinforcement and concrete.

[0141] Caisson pressure: The wharf platform is a rigid platform. The maximum weight of the caisson to be transported is 2777t, and the caisson dimensions are 18.75m × 16.75m × 19m. The equivalent pressure exerted by the caisson's own weight on the wharf platform is:

[0142] p = 2777 × 10 ÷ 18.75 ÷ 16.75 = 88.42 kPa, and the design pressure is taken as 90 kPa;

[0143] Overlap load: 1200t; (1200t / 24m=500kN / m);

[0144] Mooring force: As required by the project department, two 350kN bollards are arranged at the front edge of wharf platform 1;

[0145] Horizontal force of caisson towing on barge: During the process of loading the caisson onto the barge, when the caisson is above the departure wharf, under the traction of the winch, the rolling friction force of the airbag (the rolling friction coefficient of the airbag is taken as an empirical value of 0.05): 2777t×0.05=1388.5kN;

[0146] The earth pressure of the two stones in the caisson transport channel on the wharf platform 1; the earth pressure is determined based on the density and height of the soil layer on site.

[0147] Load combination: The ultimate limit state of load capacity is calculated by combining the effects of sustained conditions.

[0148] Load combinations:

[0149] ① Self-weight × 1.2 + Uniform load × 1.4 + Overlap load × 1.2 + Horizontal force exerted by the ship × 1.0 + Earth pressure of 1.35;

[0150] ② Self-weight × 1.2 + Equal load × 1.4 + Mooring force × 1.4 + Overlap load × 1.2 + Horizontal pulling force of caisson onto barge × 1.4.

[0151] A finite element model was established, and the pile bottom reaction force of this project was obtained through the finite element model. Figure 8 , Figure 9 , Figure 10 As shown, where: Figure 8 This is a schematic diagram of the pile bottom reaction force when the caisson is located at the rear edge of wharf platform 1. Figure 9 This is a schematic diagram of the pile bottom reaction force when the caisson is located in the middle of wharf platform 1. Figure 10 This is a schematic diagram of the pile bottom reaction force when the caisson is located at the front edge of the wharf platform 1; as can be seen from the figure, the maximum value of the pile bottom reaction force is 3857.5kN.

[0152] The design values ​​for the vertical ultimate bearing capacity of a single steel pipe pile are as follows:

[0153]

[0154] Table 1 Design values ​​of vertical ultimate bearing capacity of single steel pipe pile

[0155] The bearing stratum of the steel pipe pile is strongly weathered granite, and the vertical ultimate bearing capacity of a single pile can reach 4183.52kN>3857.5kN. The design bearing capacity of pile 11 can meet the requirements.

[0156] Strength verification of steel pipe piles, finite element analysis, etc. Figure 11 As shown in the figure, calculations show that a φ1200mm steel pipe pile (wall thickness 18mm) can meet the usage requirements.

[0157] The buckling stability of the steel pipe piles was checked, and the table below shows that the slenderness ratio and stability of the steel pipe piles meet the requirements.

[0158]

[0159] Table 2. Verification of Slenderness Ratio of Steel Pipe Piles

[0160] According to the review formula: The stability verification table for steel pipe piles (Q345 steel) is as follows:

[0161]

[0162] Table 3. Stability Verification Table for Steel Pipe Piles

[0163] It can be concluded that the stability of the steel pipe piles meets the requirements.

[0164] Punching shear resistance calculation for wharf platforms: Under local loads or concentrated reactions, the punching shear capacity of slabs without stirrups or bent-up bars should meet the following requirements:

[0165] F1≤(0.7β h f t +0.25σ pc,m )ημ m h0

[0166] The coefficient η in the formula should be the smaller value among the following formulas:

[0167]

[0168] In the formula:

[0169] β h —The cross-sectional height influence coefficient is set to 1 when h is not greater than 800mm and to 0.9 when h is not less than 2000mm; in between, it is taken by linear interpolation.

[0170] f t —Design value of axial tensile strength of concrete;

[0171] σ pc,m —The effective prestress of concrete in two directions along the perimeter of the calculated section should be weighted by length and controlled within the range of 1.0 N / m² to 3.5 N / m².

[0172] μ m —Calculate the perimeter of the section by taking the most unfavorable perimeter of the vertical section of the plate at a distance of h0 / 2 from the perimeter of the local load or concentrated reaction force action surface;

[0173] h0—Effective height of the cross section;

[0174] β s—When the area of ​​action of local load or concentrated load reaction force is rectangular, the ratio of the length of the long side to the length of the short side should not be greater than 4; when it is less than 2, take 2; for circular punched surfaces, take 2.

[0175] α s —Column position influence coefficient: 40 for middle column; 30 for side column; 20 for corner column.

[0176] Calculations show that the punching shear bearing capacity of the wharf platform is 9415kN > 3857.5kN, which meets the requirements.

[0177] Perform overall stability calculations on the bank slope:

[0178] The average load for slope stability is calculated based on the standard value of 90 kPa, and the overall stability of the outbound terminal is calculated using the Ordinary analysis method of the "GeoStudioSlope" software.

[0179] Please see Figure 12 , Figure 12 The results are from the slope stability analysis.

[0180] No caissons may be stored on either side of the transport route; they should be treated as empty. A correction factor for the slope stability resistance can be considered.

[0181] Corrected partial factors for slope stability resistance considering lateral friction: Ls = 45.39m; Lt = 24m; A = 667.4m²; Corrected resistance partial factor: γ' R =0.991×(1+667.4 / (2×24×45.3))=1.29>1; Considering the correction, the slope stability can meet the specifications, and it is required that no caissons be stored on both sides of the transport channel and be treated as empty.

[0182] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A caisson transport terminal system, characterized in that, include: The dock platform (1) has a land-facing side (17) and a sea-facing side (18) arranged opposite to each other, the sea-facing side (18) extending out of the coastline; At least two foundation piles (11) support the wharf platform (1), the upper end of the foundation piles (11) is embedded in the wharf platform (1), and the foundation piles (11) are steel pipe piles; Sheet piles (12) are installed on the land-facing side (17) of the wharf platform (1). The lower part of the sheet piles (12) is embedded and fixed. On the upper part of the sheet piles (12) away from the wharf platform (1), there are piles of stones. It also includes an outbound channel (2) connecting the dock platform (1), a transition stone layer (21) is provided at the connection between the outbound channel (2) and the dock platform (1), the surface layer of the outbound channel (2) and the dock platform (1) are both connected to the transition stone layer (21), and the transition stone layer (21) is filled with stones; The surface of the outbound channel (2) is inclined, and the dock platform (1) is located at the lower end of the inclination; A crushed stone cushion layer (13) is provided between the dock platform (1) and the transition block stone layer (21) below it, and the crushed stone cushion layer (13) is filled with crushed stone; The upper part of the sheet pile (12) is embedded in the transition boulders layer (21).

2. The caisson shipping terminal system according to claim 1, characterized in that, The foundation piles (11) are arranged in rows along the offshore direction, and the row of foundation piles (11) closest to the seaside side (18) is densely arranged.

3. The caisson shipping terminal system according to claim 1, characterized in that, The pier platform (1) is provided with a slope surface (14) below it, and the surface of the slope surface (14) is provided with a riprap face (15); at least part of the foundation piles (11) pass through the riprap face (15).

4. The caisson transport terminal system according to claim 1, characterized in that, A semi-submersible barge connection platform (3) is provided on the seaward side (18) of the wharf platform (1), and the upper surface of the semi-submersible barge connection platform (3) is lower than the upper surface of the wharf platform (1).

5. The caisson transport terminal system according to claim 4, characterized in that: The upper surface of the semi-submersible barge lap platform (3) is provided with a supporting steel plate (31). A rubber pad (32) is provided on the seaside (18) of the dock platform (1), and the rubber pad (32) is located above the semi-submersible barge connecting platform (3); The wharf platform (1) and the semi-submersible barge connection platform (3) are set up as a whole.

6. The caisson transport terminal system according to claim 4, characterized in that, A mooring bollard (16) is provided on the seaward side (18) of the wharf platform (1); the wharf platform (1) is thickened near the semi-submersible barge connection platform (3).

7. A construction method for a caisson transport terminal system as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Drive the foundation pile (11) into the designed location, wherein the foundation pile (11) is a steel pipe pile; Excavate a transition trench (22), which is located on the landward side (17) of the designed location of the wharf platform (1). The sheet piles (12) are driven into the transition groove (22), and boulders are laid on both sides of the sheet piles (12); S2. Cast-in-place the wharf platform (1), with the top of the foundation pile (11) embedded in the bottom of the wharf platform (1), and the land-facing side (17) of the wharf platform (1) abutting the sheet pile (12).

8. A design method for a caisson transport terminal system as described in any one of claims 1-6, characterized in that, Includes the following steps: A1. Determine the maximum load-bearing capacity of the wharf platform (1) based on the caisson; A2. The structure of the wharf platform (1) is designed based on the maximum load-bearing capacity of the wharf platform (1); A3. Determine the self-weight of the wharf platform (1) based on its structure; A4. Based on the maximum load-bearing capacity of the wharf platform (1), the self-weight of the wharf platform (1), the overlapping load, the mooring force, the horizontal force of the caisson being pulled onto the barge, and the earth pressure exerted on the wharf platform by the caisson transport channel stone retaining wall, load combination is performed. A5. Based on the structure and load combination structure of the wharf platform (1), construct a design model for the caisson transport wharf system; A6. Based on the design model of the caisson shipping terminal system, calculate whether the strength and stiffness of the steel pipe piles meet the design requirements. If not, modify the structure of the terminal platform (1) in step A2 and repeat steps A3-A6 until the strength and stiffness of the steel pipe piles meet the design requirements and obtain the terminal platform (1) structure that meets the design requirements. A7. Based on the wharf platform (1) structure that meets the design requirements, calculate the punching shear bearing capacity of the slab without stirrups or bent-up bars under local loads or concentrated reaction forces, and whether the overall stability of the bank slope meets the design requirements. If not, modify the wharf platform (1) structure in step A2 and repeat steps A3-A6 until the strength and stiffness of the steel pipe piles meet the design requirements, and obtain the wharf platform (1) structure that meets the design requirements.

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