A construction method for bridge foundation and a deep-water precast structure

Abstract

The present application relates to a construction method for a bridge foundation and a deep-water prefabricated structure, including a caisson and a bearing platform. A first passage is provided at the top of the caisson; the bearing platform is connected to the top of the caisson and covers the first passage, and a second passage penetrating through it is provided on the bearing platform; and the first passage, the second passage and the inner cavity of the caisson are communicated to jointly form a working passage for construction, and the cutting edge at the bottom of the caisson is adapted to the foundation. During use, it is not necessary to drive bored piles, and the foundation without overburden will not be damaged; construction can be carried out on the top of the bearing platform, and construction workers do not need to be located in the caisson. In the early stage of construction, the deep-water prefabricated structure serves as a construction platform to provide an installation position for the cleaning device; when pouring the bridge foundation after cleaning, the deep-water prefabricated structure serves as a pouring formwork for pouring. In the later stage of construction, the deep-water prefabricated structure and the concrete poured into it form the bridge foundation, serving as a part of the bridge foundation, avoiding material waste and reducing construction steps.

Description

Technical Field

[0001] This application relates to the field of bridge foundation construction, and particularly relates to a construction method for a bridge foundation and a deep-water precast structure. Background Art

[0002] At present, cross-sea bridges are generally deep-water bridges, mostly adopting long-span structures and deep-water foundations; compared with inland bridges, the lower structures and foundations of deep-water bridges are not only subjected to self-weight loads and traffic loads, but also invaded by ocean dynamic loads such as breaking waves and water currents; among them, bridge foundations are generally set by means of pile foundations and foundation setting construction methods.

[0003] In some related technologies, the construction process of the pile foundation is as follows: first, a drilling platform is set up, and the drilling platform is used for constructing and driving the drilled piles; then, a cofferdam is set up and sunk to the seabed. After landing, the drilled piles are used to form a construction platform for soil extraction and slag suction operations until the design depth is reached; then, underwater blinding concrete is gradually poured, and finally the bridge foundation is formed. However, there are the following problems:

[0004] (1) In some cases without overburden, when the foundation is a rock stratum with good bearing capacity, drilling the foundation to set the drilled piles will damage the originally stable structure of the foundation during the drilling process, and it is also difficult to drive the drilled piles, resulting in high construction costs.

[0005] (2) Due to the setting of the drilled piles and the drilling platform, the number of temporary structures increases, resulting in increased construction costs and complex construction steps, thereby reducing the efficiency; in addition, the temporary structures cause an increase in volume, making them more affected by wave forces.

[0006] In some other related technologies, when using the foundation setting construction method, an air pressure caisson is often used for construction. Specifically: the caisson is transported to the sinking position. When the caisson is sunk underwater, compressed air is sent into the air lock and the caisson working chamber through the air storage cylinder and the oil separator by an air compressor outside the caisson, and the water pressure in the working chamber is pumped out of the chamber; the staff can enter the working chamber through the personnel air lock, the central air lock and the escalator in the air cylinder to work, and clean the foundation, so that the caisson sinks to the design position, and finally concrete is filled and grouted. However, there are the following problems:

[0007] (3) The foundation setting has relatively high requirements for the flatness of the foundation. Before the caisson sinks, the entire foundation needs to be leveled. If the foundation is uneven, it will increase the difficulty of underwater leak stoppage and is not convenient for operation.

[0008] (4) Since the air pressure in the working chamber is gradually changed to enable the staff to adapt to the air pressure difference between the inside and outside of the chamber, but the air pressure is still relatively high compared to the ground, long-term operation in the working space will cause certain harm to the physical health of the construction personnel. Summary of the Invention

[0009] An embodiment of the present application provides a construction method for a bridge foundation and a deep - water prefabricated structure to solve the influence brought by the construction form of pile foundation in the related art.

[0010] In a first aspect, a deep - water prefabricated structure is provided, which includes:

[0011] A caisson, having a first passage at its top;

[0012] A bearing platform, connected to the top of the caisson and covering the first passage, and a second passage penetrating through the bearing platform is provided; and,

[0013] The first passage, the second passage and the inner cavity of the caisson are communicated with each other and jointly form a working passage for construction.

[0014] In some embodiments, the bearing platform is a box body, the inside of the box body is hollow, and a second opening is provided at the bottom;

[0015] Partition walls are provided on the top of the box body, arranged vertically and horizontally, and a first opening is formed between the partition walls. The first opening, the second opening and the inner cavity of the box body form the second passage;

[0016] The top of the box body is a working platform part for installing a cleaning device.

[0017] In some embodiments, the bearing platform is a box body, and both the bottom and the top of the box body are open;

[0018] The inside of the box body is hollow and is provided with a plurality of uniformly distributed partition boards; the partition boards extend from the top of the box body to the bottom, dividing the internal space of the box body into a plurality of compartments; the compartments and the openings at the bottom and the top of the box body form the second passage;

[0019] The top of the box body and the top of the partition boards form a working platform part for installing a cleaning device.

[0020] In some embodiments, the cross - sectional area of the bearing platform gradually decreases upward from the connection with the caisson.

[0021] In some embodiments, chamfers are provided on both the left and right sides of the top of the caisson;

[0022] The chamfer on one side is not greater than the chamfer on the other side.

[0023] In some embodiments, for the cutting edges at both sides of the bottom of the caisson, the length of the cutting edge extending downward on one side is not less than the length of the cutting edge extending downward on the other side.

[0024] In some embodiments, the caisson may be a double-wall steel shell structure, and the bearing platform may be a concrete structure.

[0025] Second, a construction method for a bridge foundation is provided, including the following steps:

[0026] Manufacture the deep-water precast structure as claimed in the claims and float it to the first design position;

[0027] Sink and land it from the first design position to the second design position;

[0028] Perform underwater leak stoppage, drainage, and slag cleaning operations on the deep-water precast structure;

[0029] Pour concrete into the caisson for bottom sealing;

[0030] Lift and install the steel formwork on the top of the bearing platform to form a pouring mold with the deep-water precast structure;

[0031] Continue to pour concrete into the pouring mold to form a bridge foundation.

[0032] In some embodiments, performing underwater leak stoppage, drainage, and slag cleaning operations on the deep-water precast structure includes the following steps:

[0033] Perform the first leak stoppage at the periphery where the bottom of the deep-water precast structure contacts the foundation;

[0034] Pump out the water in the deep-water precast structure, and during the pumping process, the gravity of the deep-water precast structure is greater than the buoyancy it receives after pumping;

[0035] Perform the second leak stoppage at the inner side where the bottom of the deep-water precast structure contacts the foundation;

[0036] Perform slag cleaning operation on the foundation.

[0037] In some embodiments, before manufacturing the deep-water precast structure as a whole, it includes the following steps:

[0038] Perform local blasting on the foundation and clean the surface gravel soil and strongly weathered rock;

[0039] Determine the position of the second design position and install concrete support blocks at the second design position;

[0040] Set the extension lengths of the two side cutting edges at the bottom of the caisson according to the undulation of the foundation after cleaning and the installation position of the concrete support blocks.

[0041] The beneficial effects brought by the technical solution provided in this application include:

[0042] The embodiments of the present application provide a construction method for bridge foundations and a deep-water precast structure. A first passage is provided at the top of the caisson, and a bearing platform is provided on the top of the caisson. A working platform part is provided on the top of the bearing platform and covers the first passage for installing a cleaning device. The bearing platform is provided with a second passage penetrating through it. The first passage, the second passage and the inner cavity of the caisson are connected to form a working passage for construction. During use, after the deep-water precast structure lands and drains water, during the process of cleaning the foundation, the cleaning device is installed on the top of the bearing platform, and the operations of soil extraction and slag suction are carried out through the working passage. On the one hand, this structure does not require bored piles to be set on the foundation to form a soil extraction platform, and will not damage the firm and stable foundation. Similarly, construction workers do not need to be located in the caisson for a long time and can carry out construction on the top of the bearing platform. Therefore, it is possible to avoid the damage of the pile foundation to the hard foundation and the impact of foundation construction on the operators.

[0043] On the other hand, in the early stage of construction, the deep-water precast structure participates in the foundation cleaning construction and pouring as a construction platform and a casting formwork; in the later stage of construction, it serves as a part of the bridge foundation, thus avoiding material waste and reducing construction steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 It is a schematic diagram of the deep-water precast structure provided by the embodiments of the present application;

[0046] Figure 2 It is a schematic diagram of the structure of the bridge foundation provided by the embodiments of the present application.

[0047] In the figure: 1. Caisson; 2. Bearing platform; 20. Working platform part; 3. Partition board; 4. Compartment; 5. Chamfer; 6. Foundation; 7. Concrete; 8. Concrete support block; 9. Tower column. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0049] An embodiment of the present application provides a deep - water prefabricated structure to solve the impacts brought by the construction form of pile foundation in the related art.

[0050] Please refer to Figure 1 and Figure 2 , a deep - water prefabricated structure, including a caisson 1 and a bearing platform 2. A first channel is provided at the top of the caisson 1, that is, the caisson 1 has no upper cover compared with a general caisson;

[0051] The bearing platform 2 is connected to the top of the caisson 1 and covers the first channel. A second channel is provided through the bearing platform 2; and the first channel, the second channel and the inner cavity of the caisson 1 are communicated to jointly form a working channel for construction.

[0052] During use, after the caisson 1 of the deep - water prefabricated structure is landed, during the process of draining water and cleaning the foundation, the cleaning device can be installed on the top of the bearing platform 2. Through the working channel, the working part of the cleaning device performs operations of draining water, taking soil and sucking slag; on the one hand, this kind of structure does not require the setting of bored piles on the foundation 6 to form a soil - taking platform, and will not damage the firm and stable foundation without overburden, making use of the structural stability of the foundation itself; also, construction workers do not need to be located in the caisson for a long time, and the cleaning device can be set on the top of the bearing platform for construction. Therefore, it realizes the avoidance of the damage of the pile foundation to the hard foundation 6 and the impact of foundation construction on the operators.

[0053] On the other hand, in the early stage of construction, the deep - water prefabricated structure serves as a construction platform to provide an installation position for the cleaning device;

[0054] When pouring the bridge foundation after cleaning, the deep - water prefabricated structure serves as a pouring formwork for pouring.

[0055] In the later stage of construction, the deep - water prefabricated structure and the concrete poured therein form the bridge foundation. The deep - water prefabricated structure serves as a part of the bridge foundation, thus avoiding material waste and reducing construction steps. This structure enables the setting of the bridge foundation without the need to float the whole bridge foundation. By dividing the bridge foundation into a deep - water prefabricated structure and a part of poured concrete, compared with the original prefabricated integral bridge foundation which is difficult to float and position due to its large weight, the problem is improved.

[0056] In addition, compared with the form of pile foundation, there is no need to set up additional temporary structures, reducing the construction cost, construction period, and also reducing the impact of wave force on it.

[0057] In some preferred embodiments, the following settings are made for the structural form of the bearing platform 2:

[0058] First, the bearing platform 2 is a box body with a hollow interior and a second opening at the bottom; there are partition walls arranged vertically and horizontally on the top of the box body, and a first opening is formed by the intersection between the partition walls. The first opening, the second opening, and the inner cavity of the box body form a second channel.

[0059] Second, the bearing platform 2 is a box body with openings at both the bottom and the top; the interior of the box body is hollow, and there are multiple evenly distributed partition plates 3 inside. The partition plates 3 extend from the top of the box body to the bottom, dividing the interior space of the box body into multiple compartments 4. The compartments 4 and the openings at the bottom and the top of the box body form a second channel. The use of the partition plates 3 is for the stability of the overall structure of the bearing platform 2.

[0060] Both of the above two structures can be adopted, aiming to expand the space inside the bearing platform 2 and reduce the overall weight of the bearing platform 2.

[0061] In some preferred embodiments, the shape of the bearing platform 2 can also be other forms, that is, it can be designed according to the form of the upper structure of the bridge. For example Figure 2 As shown, the upper part of the bridge is a tower column 9. To match the form of the tower column 9, the cross-sectional area of the bearing platform 2 gradually decreases upward from the connection with the caisson 1. Such a form can make the bridge foundation a part of the tower column 9.

[0062] In some preferred embodiments, considering the influence of water flow, chamfers 5 are provided on both the left and right sides of the top of the caisson 1. The chamfers 5 can be arc-shaped or other shapes to reduce the influence of water flow.

[0063] At the same time, considering that the water flow velocities on both sides of the caisson 1 are inconsistent, the chamfer 5 on one side is not greater than the chamfer 5 on the other side, that is, there are the following two situations:

[0064] The angle of the chamfer 5 on one side is equal to the angle of the chamfer 5 on the other side; the angle of the chamfer 5 on one side is greater than the angle of the chamfer 5 on the other side.

[0065] Furthermore, due to the inconsistent undulating shapes of the hard foundation and the inconsistent height differences of its two ends relative to the horizontal plane, in order not to damage the foundation, the cutting edges at both sides of the bottom of the caisson 1 are set as follows:

[0066] The length of the cutting edge extending downward on one side is not less than the length of the cutting edge extending downward on the other side, and the specific situation is set according to the foundation conditions to make the best use of the foundation.

[0067] This setting also avoids the requirement for the flatness of the foundation in the traditional setting of the foundation. When the foundation is uneven, it is not necessary to level it. Just make the cutting edges at both sides of the bottom of the caisson 1 match, which makes the leakage prevention relatively easy.

[0068] In the above structure, the caisson 1 can be a double-wall steel shell structure, and the bearing platform 2 can be a concrete structure. As a part of the bridge foundation, the caisson 1 reduces the self-weight of the deep-water precast structure, facilitating floating transportation. Additionally, the concrete structure of the bearing platform 2 ensures that during the construction dewatering process, buoyancy will not cause the position of the deep-water precast structure to shift, even if the gravity of the deep-water precast structure is greater than the buoyancy it receives after dewatering.

[0069] A construction method for a bridge foundation is proposed, which uses the above deep-water precast structure for construction and includes the following steps:

[0070] Manufacture the deep-water precast structure in a factory or dock and float it to the first design position; the first design position is at the horizontal plane directly above the foundation where it is to be seated; the foundation is the installation location of the bridge foundation.

[0071] Then sink the precast structure and pour concrete between its double-wall steel shells to increase the gravity and make it descend to the second design position; the second design position is the position where it is seated on the foundation.

[0072] Install a cleaning device on the top of the bearing platform 2 to perform plugging, drainage, and slag cleaning operations on the deep-water precast structure.

[0073] Pour concrete 7 into the caisson 1 of the deep-water precast structure for bottom sealing operation.

[0074] Lift and install the steel formwork on the top of the bearing platform 2 to form a pouring mold with the deep-water precast structure.

[0075] Continue to pour concrete 7 into the pouring mold to form the bridge foundation.

[0076] Through the above steps, using the deep-water precast structure, in the early stage of construction, the deep-water precast structure serves as a construction platform, providing an installation position for the cleaning device; when pouring the bridge foundation after cleaning, the deep-water precast structure serves as a pouring mold for pouring. There is no need to set up another formwork separately, reducing waste of materials and costs.

[0077] In the later stage of construction, the deep-water precast structure and the concrete poured into it form the bridge foundation, and the deep-water precast structure serves as a part of the bridge foundation, thus avoiding waste of materials and reducing construction steps.

[0078] In some preferred embodiments, the underwater plugging, drainage, and slag cleaning operations on the deep-water precast structure include the following steps:

[0079] At the periphery where the bottom of the deep-water precast structure contacts the foundation 6, perform circumferential dumping of ton bags (filled with crushed stones or pebbles) and block stones, and then lay a part of the cushion to complete the first plugging.

[0080] After the pumping is completed, the staff can enter the inner cavity of the caisson 1. On the inner side where the bottom of the deep-water precast structure contacts the foundation 6, a part of the cushion is laid for the second leak stoppage; this operation does not take long inside the caisson 1 and can be completed after the leak stoppage; the two leak stoppages ensure that there is no water flow inside during the bottom sealing, ensuring the bottom sealing effect. During the pumping process, the gravity of the deep-water precast structure is always greater than the buoyancy it receives after pumping.

[0081] Use the cleaning device to carry out the slag cleaning operation on the foundation 6. The cleaning device has the functions of draining water, sucking soil, and discharging slag, and can refer to the device used in the open caisson construction.

[0082] In some preferred embodiments, before the overall manufacture of the deep-water precast structure, the following steps are included:

[0083] Carry out local blasting on the foundation 6, and only clean the surface gravel soil and strongly weathered rock part, and clean down to 2 - 5 m until the foundation meets the applicable requirements; for the above drainage and cleaning operations, this cleaning step is to clean the remaining gravel soil and strongly weathered rock.

[0084] Determine the second design position on the foundation 6, and install the concrete support blocks 8 at the second design position. The setting of the concrete support blocks 8 can be referred to in the appendix Figure 1 Carry out the setting. The concrete support blocks 8 are at least divided into two groups, and two concrete support blocks 8 in each group are set at the designed spacing. The space between the two concrete support blocks 8 is used to contact the corresponding side of the caisson 1 for strengthening the accurate positioning of the caisson 1. The distance between the two groups of concrete support blocks 8 is approximately equal to the distance between the two sides of the caisson 1.

[0085] According to the undulation situation of the foundation 6 after cleaning, the setting situation and installation position of the concrete support blocks 8, set the extension lengths of the two side blades at the bottom of the caisson 1.

[0086] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0087] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0088] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A construction method for a bridge foundation, characterized in that, it includes the following construction steps: Manufacture a deep - water precast structure and float it to the first design position; Sink the precast structure, pour concrete between the double - wall steel shells of the precast structure to increase the gravity, so that it sinks from the first design position and lands on the second design position; Conduct underwater leak - plugging, drainage and slag - cleaning operations on the deep - water precast structure; Pour concrete (7) into the caisson (1) for bottom sealing; Lift and install the steel formwork on the top of the bearing platform (2) to form a pouring mold with the deep - water precast structure; Continue to pour concrete (7) into the pouring mold to form a bridge foundation; The underwater leak - plugging and drainage operations on the deep - water precast structure include the following steps: Conduct the first leak - plugging at the periphery where the bottom of the deep - water precast structure contacts the foundation (6); Pump out the water inside the deep - water precast structure, and during the pumping process, the gravity of the deep - water precast structure is greater than the buoyancy it receives after pumping; Conduct the second leak - plugging at the inner side where the bottom of the deep - water precast structure contacts the foundation (6); The deep - water precast structure includes: A caisson (1) with a first passage at its top; A bearing platform (2) connected to the top of the caisson (1) and covering the first passage, and a second passage penetrating through it is provided on the bearing platform (2); and, The first passage, the second passage and the inner cavity of the caisson (1) are connected and jointly form a working passage for construction. The top of the bearing platform (2) is used for installing a cleaning device, Through the working passage, the working part of the cleaning device conducts operations of draining water, taking soil and sucking slag; The caisson (1) is of a double - wall steel shell structure; The bearing platform (2) is a box body, the inside of the box body is hollow, and a second opening is provided at the bottom; The top of the box body is provided with partition walls arranged in a vertical and horizontal cross - pattern, a first opening is formed between the partition walls, and the first opening, the second opening and the inner cavity of the box body form the second passage; The top of the box body is a working platform part (20) for installing a cleaning device; Or, The bearing platform (2) is a box body with both the bottom and the top open; The inside of the box body is hollow and is provided with a plurality of uniformly distributed partition boards (3); the partition boards (3) extend from the top of the box body to the bottom, dividing the internal space of the box body into a plurality of compartments (4); the compartments (4) and the openings at the bottom and top of the box body form the second passage; The top of the box body and the top of the partition boards (3) form a working platform part (20) for installing a cleaning device; Both the left and right sides of the top of the caisson (1) are provided with chamfers (5); One of the chamfers (5) is larger than the other chamfer (5); For the cutting edges at both sides of the bottom of the caisson (1), the length of the cutting edge extending downward on one side is less than the length of the cutting edge extending downward on the other side.

2. The construction method for a bridge foundation according to claim 1, characterized in that: The cross - sectional area of the bearing platform (2) gradually decreases upward from the connection with the caisson (1).

3. The construction method for a bridge foundation according to claim 1, characterized in that: The bearing platform (2) is of a concrete structure.

4. The construction method of the bridge foundation according to claim 1, characterized in that, before the overall fabrication of the deep-water precast structure, the following steps are included: conduct local cleaning of the foundation (6); determine the position of the second design position and install a concrete support block (8) at the second design position; set the extension lengths of the two side cutting edges at the bottom of the caisson (1) according to the undulation of the foundation (6) after cleaning and the installation position of the concrete support block (8).

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