CN112252367A - Negative buoyancy immersed tube and prefabricating method thereof - Google Patents
Negative buoyancy immersed tube and prefabricating method thereof Download PDFInfo
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- CN112252367A CN112252367A CN202011287920.8A CN202011287920A CN112252367A CN 112252367 A CN112252367 A CN 112252367A CN 202011287920 A CN202011287920 A CN 202011287920A CN 112252367 A CN112252367 A CN 112252367A
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- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000007667 floating Methods 0.000 claims abstract description 55
- 238000013461 design Methods 0.000 claims abstract description 43
- 238000009417 prefabrication Methods 0.000 claims abstract description 35
- 238000007789 sealing Methods 0.000 claims description 5
- 238000005266 casting Methods 0.000 claims 1
- 238000010276 construction Methods 0.000 abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 26
- 210000001503 joint Anatomy 0.000 description 19
- 238000009434 installation Methods 0.000 description 10
- 230000008878 coupling Effects 0.000 description 6
- 238000010168 coupling process Methods 0.000 description 6
- 238000005859 coupling reaction Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000013535 sea water Substances 0.000 description 5
- 239000002699 waste material Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 3
- 239000003643 water by type Substances 0.000 description 3
- 230000005484 gravity Effects 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/063—Tunnels submerged into, or built in, open water
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Abstract
The invention relates to the technical field of immersed tube tunnel construction, in particular to a negative buoyancy immersed tube and a prefabricating method thereof. The pipe joints do not need to be designed to be self-floating in corresponding water areas, so that the section height of the immersed pipe does not need to be increased for ensuring the minimum freeboard value during floating transportation, the design contradiction between freeboard value and anti-floating in the operation period in the design link is avoided, the freeboard value is not needed to be detected by a dry dock, and the method is particularly suitable for field-limited engineering projects. The design concept that self-floating immersed tube is adopted in the prior art is broken through, the structural height can be reduced to the maximum extent, the engineering quantities such as a main structure and foundation trench backfill are saved, a freeboard adjusting layer is not required to be arranged, the prefabrication cost and the construction cost are effectively saved, the design difficulty and the prefabrication difficulty are favorably reduced, the fussy operation that the freeboard value is adjusted in water in a floating transportation link is avoided, the transportation time is favorably shortened, and the method has important popularization significance and good application prospect.
Description
Technical Field
The invention relates to the technical field of immersed tube tunnel construction, in particular to a negative buoyancy immersed tube and a prefabricating method thereof.
Background
Buoyancy design must be considered in the design of the immersed tube structure, including the selection of a freeboard and the verification of an anti-floating safety coefficient. The immersed tube prefabrication in the prior art mainly comprises a dry dock method and a factory method, the factory method is high in prefabrication efficiency and is often suitable for projects with tight construction periods, and prefabricated pipe sections reach designed construction positions through floating transportation to be immersed. At present, no matter what prefabrication method is adopted, a main board pipe joint is adopted, namely the pipe joint can float in water when floating, and the top surface of the pipe joint needs to be exposed out of the water. In order to ensure the safety and stability of the pipe joints in the floating transportation process, the pipe joints are adjusted to a designed freeboard value (the exposed height) which is usually about 10-30cm through a ballast water tank system arranged in the pipe joints before floating transportation, and then the immersed pipes are floated and transported to an installation site from a prefabrication field by using a tug unit by utilizing the self-floating characteristic of the immersed pipes.
Therefore, in order to meet the minimum normal freeboard value, the section height of the pipe joint is often larger, so that the engineering quantity of a main body structure, foundation trench backfill and the like is increased, and the prefabrication cost and the construction cost are increased; and after the pipe joint rises, the freeboard value is tested, the negative buoyancy of the pipe joint is regulated in water through a ballast water tank system in order to meet the requirement of the corresponding anti-floating coefficient in the existing specification in the floating transportation and sinking processes, the precision control is complex, and the construction difficulty is known.
Disclosure of Invention
The invention aims to overcome the defects that the section height of a pipe joint is larger, the engineering quantity of a main body structure, foundation trench backfill and the like is increased, the prefabrication cost and the construction cost are increased, and the construction difficulty is large due to the fact that the design of immersed pipes in the prior art needs to meet the minimum freeboard value, and provides a negative buoyancy immersed pipe and a prefabrication method thereof.
In order to achieve the above purpose, the invention provides the following technical scheme:
a negative buoyancy immersed tube comprises a body, wherein the designed freeboard value of the body is less than 0.
By adopting the negative buoyancy immersed tube, the existing tube joints are designed by adopting the positive freeboard value, the design freeboard value is less than 0, namely, the tube joints are negative freeboard tube joints relative to the positive freeboard tube joints in the prior art, namely, the tube joints are not required to be designed to be capable of floating in a corresponding water area, but a negative buoyancy state of the immersed tube in the prior art in the sinking and butting links is formed, so that the cross section height of the immersed tube is not required to be increased for ensuring the minimum positive freeboard value during floating transportation, the design contradiction between the freeboard value and anti-floating in the operation period in the design link is avoided, a dry dock is not required to be arranged for detecting the freeboard value, and the negative buoyancy immersed tube is particularly suitable for engineering projects with limited fields. The design concept that self-floating immersed tube is adopted in the prior art is broken through, the structural height can be reduced to the maximum extent, the engineering quantities such as a main structure and foundation trench backfill are saved, a freeboard adjusting layer is not required to be arranged, the prefabrication cost and the construction cost are effectively saved, the design difficulty and the prefabrication difficulty are favorably reduced, the fussy operation that the freeboard value is adjusted in water in a floating transportation link is avoided, the transportation time is favorably shortened, and the method has important popularization significance and good application prospect.
Preferably, the self-weight of the body includes the design structure self-weight G of the body0And the design dead weight of the ballast concrete in the body, wherein the design dead weight of the ballast concrete comprises the design dead weight G of the first ballast concrete1And the design dead weight G of the second ballast concrete2，G0And G1The sum is greater than the design buoyancy F of the body, and the first ballast concrete is poured when the body is prefabricated.
Wherein the design structure of the body has a dead weight G0The self weight is calculated according to the section size.
It is further preferred that the first and second liquid crystal compositions,
is 1.02-1.05.
In order to save the cost to the maximum extent and ensure that the requirement of the anti-floating coefficient in the sinking and butting construction stage is met, the anti-floating coefficient from 1.02 in the sinking and butting process to 1.05 in the sinking and in-place state or the anti-floating coefficient of the stable ballast section can be used as a control index according to the existing design specification.
In the prior art, after the pipe joints are completely sunk, ballast concrete needs to be poured to replace a ballast water tank, due to underwater operation, the construction difficulty is high, certain floating risk exists, the test and rechecking are difficult to perform after pouring, if the pouring amount is increased, the cost is increased, the material is wasted, and even in order to ensure the clearance, the clearance of the sinking pipes is additionally increased in the design stage, so that the structure size is increased. This application is along pouring the ballast concrete after current sinking, pours first ballast concrete in advance as partial pressure heavy layer at the prefabrication stage, makes the tube coupling can't be from floating in the construction waters, does benefit to and reduces the design degree of difficulty, satisfies the anti coefficient of floating requirement when sinking the replacement ballast water tank after the butt joint simultaneously, need not to introduce extra equipment or structure, can cancel ballast water tank system again, reduces construction cost, appears floating when avoiding replacing the water tank, the installation risk is little, pour the link and go on in the mill, the operation degree of difficulty is low, the risk is little, the accurate control of being convenient for pours the weight of back tube coupling, avoid the waste of extra material.
It is further preferred that the first and second liquid crystal compositions,
the requirement of the anti-floating coefficient of the body in the operation period is met.
Further preferably, the second ballast concrete is poured after the body is sunk.
The weight of the pipe joints in the transportation stage is reduced, and the transportation cost is saved.
Preferably, the ballast concrete is arranged on the top surface of the traffic lane, and the ballast concrete is plain concrete.
Further preferably, the concrete strength of the ballast concrete is smaller than the concrete strength of the body.
The prefabricated cost is favorably reduced, and the concrete strength of the ballast concrete needs to meet the driving requirements of the road surface.
A prefabrication method of a negative buoyancy immersed tube adopts the negative buoyancy immersed tube, and comprises the following steps:
a. prefabricating a body;
b. pouring first ballast concrete in the body, and measuring whether the weight of the body meets a first anti-floating coefficient;
c. after the requirements are met, installing primary outfitting parts and embedded parts;
d. and (5) installing an end sealing wall to finish the prefabrication of the negative buoyancy immersed tube.
By adopting the prefabrication method of the negative buoyancy immersed tube, the ballast concrete poured after the existing tube section is immersed is used, the first ballast concrete is poured in advance as a partial ballast layer in a factory prefabrication stage, the tube section cannot float in a construction water area, the operation difficulty is low, the risk is small, the weight of the tube section after pouring is convenient to accurately control, the waste of extra materials is avoided, the construction cost is favorably reduced, the prefabrication period cannot be obviously increased, technical guidance and operation processes are provided for the construction of the novel negative buoyancy immersed tube, and the method is worthy of wide popularization and application.
Preferably, before the step b, the method further comprises the steps of determining the dry volume weight of the concrete used for the body and calculating the theoretical weight of the body.
The pouring amount of the ballast concrete can be accurately controlled.
Further preferably, the step b comprises the following steps:
b1, after the preset strength is achieved, moving the body to an outfitting area through a trolley, and measuring the weight of the body before the first ballast concrete is poured through a pressure sensor of the trolley;
b2, determining the pouring amount of the first ballast concrete according to the theoretical weight of the body in combination with the step b1, pouring the first ballast concrete, and then measuring whether the weight of the body meets a first anti-floating coefficient and whether the weight distribution is uniform or not through a pressure sensor of the trolley;
wherein, every the platform truck all is equipped with pressure sensor.
By adopting the mode, the pouring area can be vacated as soon as possible, so that the pouring of the next pipe joint can be carried out as soon as possible, the construction period is shortened, meanwhile, the trolley for transferring the pipe joints is used as weighing equipment, the measuring process is simple and convenient, the pouring amount of the first ballast concrete can be adjusted conveniently according to actual conditions, and the trolley is widely and uniformly distributed, so that the uniformity of the weight of the pipe joints can be detected, the transportation safety is ensured, and the construction risk of the process in water is reduced.
Further preferably, the first ballast concrete is poured at least three times, and the weight distribution is measured after each pouring is finished.
Preferably, the first anti-floating coefficient is 1.02 to 1.05.
Preferably, the order of steps b and c can be interchanged or performed simultaneously.
Compared with the prior art, the invention has the beneficial effects that:
1. the design concept that self-floating immersed tubes are adopted in the prior art is broken, the structural height can be reduced to the maximum extent, the engineering quantities of a main structure, foundation trench backfill and the like are saved, a freeboard adjusting layer is not required to be arranged, the prefabricating cost and the construction cost are effectively saved, the design difficulty and the prefabricating difficulty are favorably reduced, the fussy operation that the freeboard value is adjusted in water in a floating transportation link is avoided, the transportation time is favorably shortened, and the method has important popularization significance and good application prospect.
2. Follow the ballast concrete who pours after current sinking, pour first ballast concrete in advance as partial pressure heavy layer at the prefabrication stage, make the tube coupling can't be from floating in the construction waters, do benefit to and reduce the design degree of difficulty, satisfy the anti coefficient of floating requirement after the sinking butt joint simultaneously, need not to introduce extra equipment or structure, can cancel ballast water tank system again, reduce construction cost, appear floating when avoiding replacing the water tank, the operation stage floats the risk little, the link of pouring is gone on at the mill, the operation degree of difficulty is low, the risk is little, the accurate control of being convenient for pours the weight of back tube coupling, avoid the waste of extra material.
3. The pouring area can be vacated as soon as possible, so that pouring of the next pipe joint can be carried out as soon as possible, the construction period is shortened, meanwhile, a trolley for transferring the pipe joints is used as bearing equipment, the measuring process is simple and convenient, the pouring amount of the first ballast concrete can be adjusted conveniently according to actual conditions, and the trolley is widely and uniformly distributed, so that the uniformity of the weight of the pipe joints can be detected, the transportation safety is guaranteed, and the construction risk of the underwater process is reduced.
Description of the drawings:
FIG. 1 is a schematic view of a negatively buoyant immersed tube according to the present invention;
fig. 2 is a schematic sectional view of a negatively buoyant immersed tube according to the embodiment.
The labels in the figure are: 1-bulk, 21-first ballast concrete.
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.
Examples
As shown in fig. 1, the negative buoyancy immersed tube of the present invention comprises a body 1, wherein the designed freeboard value of the body 1 is less than 0. The negative freeboard pipe joint is a negative freeboard pipe joint, namely, the design of a positive freeboard is not considered, the pipe joint is not required to be designed to be capable of floating in a corresponding water area, but a negative buoyancy state of the existing immersed pipe in the links of sinking and butting is formed, the design concept that the existing immersed pipe needs to be adopted in the prior art is broken through, the structural height can be reduced to the maximum extent, the engineering quantities of a main body structure, foundation trench backfilling and the like are saved, and a freeboard adjusting layer is not required to be arranged.
Specifically, the self-weight of the body 1 includes the design structure self-weight G of the body 10And the design dead weight of the ballast concrete inside the body 1, wherein the design structure dead weight G of the body 10Can be calculated according to the section size, and the design dead weight of the ballast concrete comprises the design dead weight G of the first ballast concrete 211And the design dead weight G of the second ballast concrete2，G0And G1The sum of the buoyancy values is larger than the designed buoyancy force F of the body 1, the first ballast concrete 21 is poured when the body 1 is prefabricated, if the body 1 is poured in a pouring area, the pouring is carried out on the first ballast concrete 21 after the body 1 is moved to an outfitting area, and the pouring area is vacated as soon as possible so as to pour the body 1 of the next section. The ballast concrete is arranged on the top surface of the traffic lane, the ballast concrete is plain concrete, and preferably, the concrete strength of the ballast concrete is less than that of the body 1. The thickness of the ballast concrete needs to meet the minimum thickness requirement controlled by the waste water pump house and the arrangement of the transverse ditch together, and the slope adjustment of the ballast concrete is carried out when the second ballast concrete is poured.
According to the current specifications, the sinking stage of the immersed tube needs to meet the anti-floating coefficient of 1.01-1.02, so G0And G1The sum of the buoyancy values is at least 1.01 times of the designed buoyancy F, and the freeboard value of the body 1 after actually entering a corresponding water area can be effectively ensured to be less than 0. If 1.02 times is selected, the body 1 realizes the negative buoyancy of 1.02 by means of self weight during installation, and realizes the negative buoyancy of 1.05 by means of a simple ballast water bag after installation, so that the cost and the construction difficulty can be properly reduced.
Meets the requirement of the anti-floating coefficient of the body 1 in the operation period according to the prior artThe specification, i.e. the anti-floating coefficient during the operation period, needs to be more than 1.06. The second ballast concrete is poured after the body 1 is sunk, so that the weight of the pipe joint in the transportation stage is reduced, and the transportation cost is saved.
Of course, it is preferred that
According to the existing design specifications, the anti-floating coefficient 1.05 of the ballast section after being sunk in place or stabilized is used as a control index, so that the cost can be saved to the maximum extent, the anti-floating coefficient requirement in the sinking and butting construction stage is met, a ballast water tank system is completely cancelled, an additional ballast device is not needed, and if the index is regulated in the specifications, the index is correspondingly regulated along with the specifications. Follow the existing ballast concrete who pours after sinking, pour first ballast concrete 21 in advance as partial pressure heavy layer in the prefabrication stage, as shown in fig. 2, make the tube coupling can't be from floating in the construction waters, do benefit to and reduce the design degree of difficulty, satisfy the anti coefficient of floating requirement after sinking the butt joint simultaneously, need not to introduce extra equipment or structure, can cancel ballast water tank system again, reduce construction cost, appear floating when avoiding replacing the water tank, the operation stage floats the risk little, the link of pouring is gone on at the mill, the operation degree of difficulty is low, the risk is little, the accurate control of being convenient for pours the weight of back tube coupling, avoid the waste of extra material.
As an example of the former bay, the construction environment in the former bay is mainly attributed as follows:
the wave heights in the foundation grooves are all less than 0.2m, the number of wave-free days is large, the number of wave-free days accounts for 29% of the whole year, and the wave heights less than 0.5m account for more than 90% of the waves; the sand content is gradually reduced from the opening to the inside; density of seawater: the density of the seawater from the outside to the inside of the bay is gradually reduced and is between 1.00 and 1.015; designing a high tide level of +1.62m and a low tide level of-0.83 m in the front bay; the average annual big wind days above grade 6 is 20 days, and the guarantee rate of the operation days below grade 6 is 94%. The rising and falling tide of the front bay is influenced by the excavation of the base groove, the maximum flow velocity of the rising and falling tide of the base groove is about 0.1m/s, and the flow velocity of a part of confluence areas is larger and is about 0.4 m/s.
The design dimensions and other parameters of the prior art immersed tube (positive topsides immersed tube) and the negative buoyancy immersed tube (negative topsides immersed tube) of the present application are as shown in table 1 below:
TABLE 1 parameter comparison Table
According to the table, the negative freeboard immersed tube is adopted, namely, the design freeboard value does not need to be considered, the design freeboard value can be negative, the section height of the immersed tube can be effectively reduced, and the engineering quantity of the structure and the foundation trench is further reduced.
The prefabrication method of the negative buoyancy immersed tube comprises the following steps:
a. prefabricating a body 1;
b. pouring first ballast concrete 21 in the body 1, and measuring whether the weight of the body 1 meets a first anti-floating coefficient;
c. after the requirements are met, installing primary outfitting parts and embedded parts;
d. and (3) installing an end sealing wall, and completing prefabrication of the negative buoyancy immersed tube as shown in figure 2 (outfitting parts, embedded parts and the end sealing wall are not shown).
The method comprises the steps of prefabricating the body 1, wherein the processes of steel bar binding, template installation and concrete pouring are the same as those of a normal-freeboard pipe joint prefabricating process in the prior art, and the method can be carried out according to the existing immersed tube prefabricating process. To ensure accuracy, the dry bulk weight of the concrete used for the body 1 can be determined in advance, and the theoretical weight of the body 1 can be calculated. In order to avoid larger errors, the weight of the immersed tube is increased or reduced, and the immersed tube cannot realize the anti-floating coefficient of 1.05, the slump of the concrete before pouring into the mould, the gravity of the fresh concrete (a test value before pouring into the mould) and the gravity of the hardened concrete (a test value of 28d after hardening) need to be strictly tested.
If the seawater density in the former bay is influenced by rivers and changes between 1.00 and 1.015g/cm3, when the immersed tube is prefabricated, the seawater density should be an upper limit value to ensure that the immersed tube meets the requirement of a preset anti-floating coefficient after hydraulic pressure welding in the construction stage, for example, the anti-floating coefficient of 1.05 is adopted, and the prefabricated theoretical weight of a tube joint is the drainage volume V multiplied by the seawater density of 1.015 multiplied by 1.05 (anti-floating coefficient).
Then, the first ballast concrete 21 is poured, the body 1 can be moved to a fitting-out area through a trolley, the pouring area can be vacated as soon as possible, so that the pouring of the next pipe joint can be carried out as soon as possible, the construction period is shortened, then the weight of the body 1 before the first ballast concrete 21 is poured is measured through a pressure sensor of the trolley, the trolley is pipe joint transfer equipment commonly used in the prior art, the distribution of the trolley is wide and uniform below the pipe joints, and each trolley is provided with a pressure sensor so as to be convenient for weighing.
Checking the pouring amount of the first ballast concrete 21 according to the theoretical weight of the body 1 in combination with the weight weighed for the first time to ensure 1.05 times of negative buoyancy, and measuring whether the weight of the body 1 meets a first anti-floating coefficient and whether the weight distribution is uniform or not through the pressure sensor of the trolley again after the first ballast concrete 21 is poured.
When the first ballast concrete 21 is poured, layered pouring is preferably adopted, pouring is carried out at least three times, the thickness of each pouring is approximately the same, the weight distribution condition of the pipe joints is measured after each pouring is finished, the hydraulic jacks of the trolley can be simultaneously used for weighing, the weight is measured by matching with the pressure sensors on the trolley, and then filtering, calibration and checking are carried out, so that the weighing accuracy is ensured.
After the requirements are met, installing primary outfitting parts and embedded parts; this step may be performed simultaneously with pouring the first ballast concrete 21, or may be performed after installation, and since the weights of the first outfitting and the embedded part may be measured in advance and basically have no change after installation, it is sufficient if the weights of the first outfitting and the embedded part are subtracted from the measured weights after installation to determine whether the anti-floating coefficient is up to standard.
And finally, installing an end sealing wall to finish the prefabrication of the negative buoyancy immersed tube.
After the body 1 is transported to the corresponding installation position and the sinking is finished, namely when the link of ballast concrete pouring and replacing the ballast water tank is carried out in the prior art, the second ballast concrete is poured, the requirement of the anti-floating coefficient in the operation period of the immersed tube is met, the corresponding negative buoyancy degree is reached, and the equipment requirement and the transportation and installation difficulty of the transportation equipment are favorably reduced.
The process of the prefabrication method of the invention and the prefabrication method of the normal freeboard pipe joint in the prior art is as shown in the following table 2:
TABLE 2 comparison table of the prefabrication process
According to the upper table, the prefabrication method can be known, the existing pipe section is used for sinking and then pouring the ballast concrete, the first ballast concrete 21 is poured in advance in the factory prefabrication stage to serve as a partial pressure heavy layer, the pipe section cannot float automatically in a construction water area, the operation difficulty is low, the risk is small, the weight of the pipe section after pouring is convenient to accurately control, the waste of extra materials is avoided, the construction cost is favorably reduced, the prefabrication period cannot be obviously increased, technical guidance and operation processes are provided for the construction of the novel negative buoyancy immersed pipe, and the method is worthy of wide popularization and application.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the present invention shall be covered thereby. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (13)
1. A negative buoyancy immersed tube is characterized by comprising a body (1), wherein the designed freeboard value of the body (1) is less than 0.
2. The sinking pipe of claim 1, wherein the dead weight of the body (1) comprises the design structure dead weight G of the body (1)0And in the body (1)The design dead weight of the ballast concrete of the section including the design dead weight G of the first ballast concrete (21)1And the design dead weight G of the second ballast concrete2，G0And G1The sum is greater than the design buoyancy F of the body (1), and the first ballast concrete (21) is cast during prefabrication of the body (1).
3. The caisson of claim 2,
is 1.02-1.05.
4. The caisson of claim 2,
the requirement of the anti-floating coefficient of the body (1) in the operation period is met.
5. Immersed tube according to claim 4, characterised in that said second ballast concrete is poured after the sinking of said body (1).
6. The sinking pipe of any one of claims 1-5, wherein the ballast concrete is provided on the top surface of the roadway, and the ballast concrete is plain concrete.
7. Sinking pipe according to claim 6, wherein the concrete strength of the ballasted concrete is less than the concrete strength of the body (1).
8. The prefabricating method of the negative buoyancy immersed tube is characterized by comprising the following steps of:
a. a prefabricated body (1);
b. pouring first ballast concrete (21) in the body (1), and measuring whether the weight of the body (1) meets a first anti-floating coefficient;
c. after the requirements are met, installing primary outfitting parts and embedded parts;
d. and (5) installing an end sealing wall to finish the prefabrication of the negative buoyancy immersed tube.
9. Prefabrication method according to claim 8, characterised in that it further comprises, before step b, determining the dry bulk weight of the concrete used for said body (1) and calculating the theoretical weight of said body (1).
10. Prefabrication method according to claim 9, characterised in that said step b comprises the following steps:
b1, after the preset strength is achieved, moving the body (1) to an outfitting area through a trolley, and measuring the weight of the body (1) before the first ballast concrete (21) is poured through a pressure sensor of the trolley;
b2, determining the pouring amount of the first ballast concrete (21) according to the theoretical weight of the body (1) in combination with the step b1, pouring the first ballast concrete (21), and then measuring whether the weight of the body (1) meets a first anti-floating coefficient and whether the weight distribution is uniform or not through a pressure sensor of the trolley;
wherein, every the platform truck all is equipped with pressure sensor.
11. Prefabrication method according to claim 10, characterised in that the first ballast concrete (21) is cast in at least three portions, the weight distribution being measured after each casting.
12. Prefabrication method as claimed in any one of claims 8 to 11, characterised in that the first anti-floating factor is between 1.02 and 1.05.
13. Prefabrication method according to any one of claims 8-11, characterised in that the order of steps b and c can be interchanged or carried out simultaneously.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113235657A (en) * | 2021-04-30 | 2021-08-10 | 四川水建建设工程有限公司 | Heavy-caliber immersed tube assembly and immersed tube method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990015223A1 (en) * | 1989-05-31 | 1990-12-13 | Transfield Construction Pty Limited | Submerged bridge tunnel |
| CN111648406A (en) * | 2020-07-03 | 2020-09-11 | 中交第四航务工程局有限公司 | Construction method for dismantling immersed tube ballast system and replacing concrete |
| CN214574130U (en) * | 2020-11-17 | 2021-11-02 | 中交第四航务工程局有限公司 | Negative buoyancy immersed tube |
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2020
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| CN113235657A (en) * | 2021-04-30 | 2021-08-10 | 四川水建建设工程有限公司 | Heavy-caliber immersed tube assembly and immersed tube method |
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