Bridge preloading system and method

Abstract

The invention discloses a bridge preloading system and method, and relates to the technical field of bridge construction.The bridge preloading system is used for a bridge, the bridge is provided with a preloading area, the bridge preloading system comprises water loading units, the water loading units are arranged in the preloading area, each water loading unit comprises a plurality of water bags, and the water bags are arranged in the preloading area. The multiple water bags are stacked in the width direction and / or the height direction of the bridge. According to the technical scheme provided by the invention, the water bag is modularized, so that the loading and unloading weight is convenient to adjust, the accurate control on the prepressing load is realized, the operation is convenient, and the bridge deformation and the settlement value overrun caused by the overrun and sudden change of the load are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge construction, and in particular to a bridge load preloading system and method. Background Art

[0002] Bridge preloading is a construction process commonly used in bridge construction. By applying a certain weight of load on the bridge structure, the actual load that the bridge will bear during use is simulated to test the bearing capacity and stability of the bridge. At the same time, it can also eliminate the inelastic deformation of some structures and make the bridge structure more stable and reliable. The traditional method is to pile iron cans or solid weights on the bridge for actual pressure testing. However, the objects are dense, difficult to transport and move, and have high testing costs, and are not suitable for transportation. The specific load standards for bridge preloading will vary depending on factors such as the type of bridge, design requirements, and construction conditions. After the prefabricated box girder is erected, if the traditional preloading method is used, it is difficult to control the loading and unloading rates, and it is difficult for operators to control the total load, making it difficult to ensure that the deformation and settlement of the bridge are within the allowable range. Summary of the invention

[0003] The main purpose of the present invention is to provide a bridge preloading system, which is designed to facilitate the control of loading and unloading.

[0004] To achieve the above-mentioned purpose, the bridge loading preloading system proposed in the present invention is used for a bridge, wherein the bridge is provided with a loading area, and the bridge loading preloading system includes a water-loading unit, which is arranged in the loading area. Each of the water-loading units includes a plurality of water bags, and the plurality of water bags are stacked in the width direction and / or height direction of the bridge.

[0005] In one embodiment, the bridge has a plurality of box girders arranged along its length direction, the top two sides of the box girders are respectively provided with a first ballast bed and a second ballast bed, and the loading area is provided in at least one between the first ballast bed and the second ballast bed and inside the box girder.

[0006] In one embodiment, the bridge preloading system further includes a support member, and the support member is disposed in the loading area to limit the water load unit.

[0007] In one embodiment, the support members are provided in plurality, and at least one water bag is provided in each support member.

[0008] In one embodiment, the bridge preloading system further comprises an observation device, which is disposed on the top of the box girder and is used to observe deformation data after preloading.

[0009] In one embodiment, a first observation point is respectively provided at the mid-span and 1 / 4 span of the side span and middle span of the bridge, and a group of the observation devices is provided at each first observation point.

[0010] In one embodiment, at least one second observation point is provided between any two adjacent first observation points, and a group of the observation devices is provided at each of the second observation points.

[0011] In one embodiment, each of the first observation point and the second observation point includes two observation sub-points, and the two observation sub-points are symmetrically arranged in the width direction of the bridge.

[0012] The present invention also provides a bridge load preloading method, comprising the following steps:

[0013] Erecting box girders: The box girders are set along the length of the bridge. The two sides of the top of the box girder are the first and second ballasts respectively. The area between the first and second ballasts and inside the box girder are used as the loading area.

[0014] Preloading: The preloading load value is calculated based on the second-phase dead load and construction load of the bridge, and the number and size of the required water bags are calculated based on the preloading load value. The water bags filled with water are placed in the loading area;

[0015] Observation: First observation points are set at the side span, middle span and 1 / 4 span of the bridge respectively, at least one second observation point is set between adjacent first observation points, and observation devices are set at each first observation point and second observation point to observe the deformation and settlement value of the bridge;

[0016] Pouring: Pour the first and second track beds, and unload the water bags with equal load weight in the loading area according to the weight of the pouring until the water bags are completely unloaded.

[0017] In one embodiment, the preloading includes multiple levels of loading, and the settlement of the bridge is observed after each level of loading is completed. When the settlement per 24 hours is less than or equal to 1 mm, the next level of loading is performed until all loading is completed.

[0018] In the technical solution of the present invention, a plurality of loading areas are arranged on the bridge, and the loading areas are used to place water load units, and the water load units are used to simulate the constant load, that is, some additional loads permanently attached to the bridge. The water load units include a plurality of water bags, and the size and quantity of the water bags are determined according to the calculated value of the preload and the structural size of the bridge, and the weight of the water added to each water bag is controlled so that the weight of each water bag is consistent, and the water bags are placed in the loading area, and the bridge is poured after being stabilized, and the water bags of corresponding weight are removed according to the weight of the poured concrete, so that the bridge is The load remains stable. By setting up multiple water bags to simulate constant load loading, uniform load distribution can be provided. Exerting balanced pressure on the bridge can avoid local overload. When not filled with water, the water bag occupies a small space and is light in weight, which is convenient for transportation. The water bag can be reused, which reduces the cost of materials and the damage to the environment by solid waste. In addition, multiple water bags filled with the same weight of water are set up and modularized to facilitate the adjustment of loading and unloading weights, thereby achieving precise control of the preload and easy operation, avoiding deformation and settlement of the bridge caused by excessive loads and sudden changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 A structural schematic diagram of an embodiment of a bridge load preloading system provided by the present invention;

[0021] Figure 2 A schematic structural diagram of another embodiment of the bridge load preloading system provided by the present invention.

[0022] Description of Figure Numbers:

[0023] 100. Loading area;

[0024] 200, water bag;

[0025] 300, box girder; 310, first track bed; 320, second track bed;

[0026] 400, support member;

[0027] 500. Observation device.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0031] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] Bridge preloading is a construction process commonly used in bridge construction. By applying a certain weight of load on the bridge structure, the actual load that the bridge will bear during use is simulated to test the bearing capacity and stability of the bridge. At the same time, it can also eliminate the inelastic deformation of some structures and make the bridge structure more stable and reliable. The traditional method is to pile iron cans or solid weights on the bridge for actual pressure testing. However, the objects are dense, difficult to transport and move, and have high testing costs, and are not suitable for transportation. The specific load standards for bridge preloading will vary depending on factors such as the type of bridge, design requirements, and construction conditions. After the prefabricated box girder is erected, if the traditional preloading method is used, it is difficult to control the loading and unloading rates, and it is difficult for operators to control the total load, making it difficult to ensure that the deformation and settlement of the bridge are within the allowable range.

[0033] The invention provides a bridge load preloading system and method.

[0034] See also Figure 1 and Figure 2In one embodiment of the present invention, the bridge preloading system is used for a bridge. The bridge is provided with a loading area 100. The bridge preloading system includes a water-carrying unit. The water-carrying unit is provided in the loading area 100. Each water-carrying unit includes a plurality of water bags 200. The plurality of water bags 200 are stacked in the width direction and / or height direction of the bridge.

[0035] In the technical solution of the present invention, a plurality of loading areas 100 are arranged on the bridge, and the loading areas 100 are used to place water load units, which are used to simulate constant load loading, that is, some additional loads permanently attached to the bridge. The water load units include a plurality of water bags 200, and the size and quantity of the water bags 200 are determined according to the preload and the structural size of the bridge, and the weight of the water added to each water bag 200 is controlled so that the weight of each water bag 200 is consistent, and the water bag 200 is placed in the loading area 100, and the bridge is poured after being stabilized, and the water bag 200 of corresponding weight is removed according to the weight of the poured concrete. The load on the bridge is kept stable. By setting up multiple water bags 200 to simulate constant load loading, uniform load distribution can be provided, and balanced pressure can be applied on the bridge to avoid local overload. The water bag 200 occupies a small space when not filled with water, is light in weight, and is easy to transport. The water bag 200 can be reused, which reduces the cost of materials and the damage to the environment by solid waste. In addition, multiple water bags 200 filled with the same weight of water are set up and the water bags 200 are modularized to facilitate the adjustment of the loading and unloading weights, thereby achieving precise control of the preload and easy operation, thereby avoiding deformation and settlement of the bridge caused by excessive loads and sudden changes.

[0036] Specifically, this technical solution is used to carry out a second-phase prestressing of the bridge, that is, a persistent load in addition to the first-phase constant load during the operation phase of the bridge. The prestressing load is the constant load on the box girder and the construction load. The constant load includes but is not limited to the weight of the base plate, ballast plate, rails, steel bars, sleepers, fasteners and bridge deck systems. Various permanent loads added to the bridge later are also considered, including but not limited to additional loads such as railings, crash barriers, lights and traffic signs. The weight of the constant load is the weight of the ballastless track, that is, the total weight of the structures such as the ballast plate, rails, steel bars, sleepers, fasteners and bridge deck systems. The total weight is calculated through the total length and bulk density of the bridge. For example, the ballast plate is calculated by multiplying its length per meter by its required width and height combined with its density. The weight per meter of its length is obtained, and then combined with the total length of the bridge to obtain the weight of the required roadbed plate. The total weight of the rails is obtained by multiplying the weight of each meter of the rails by the total length of the bridge. The calculation of steel bars, sleepers, fasteners and bridge decks is the same as above. The required constant load value is calculated by multiplying the load weight per meter by the total length of the bridge. The construction load is a dynamic load, including but not limited to the dynamic load generated by construction personnel walking on the working surface, operating tools and small construction equipment (such as vibrators), or when pumping concrete, the pressure generated during the pumping process is transmitted to the support system through the delivery pipe. Therefore, its weight calculation is also divided into multiple parts, such as the construction personnel load and equipment load. The construction personnel load is usually calculated at 2.5kN / m per person. 2 Calculation: If the construction area is A square meters, the construction personnel load is 2.5A Newtons. The equipment load needs to be calculated based on the type and weight of the equipment used. For example, small equipment such as vibrators can generally be considered at 1kN per unit, while larger equipment is calculated based on its actual weight and area of ​​action. The impact load of concrete pouring also needs to be considered, because concrete pouring will generate an impact load, which can generally be taken as 2kN / m 2 If the dumping area is B square meters, the impact load is 2B Newtons. Then there is the concrete pumping pressure load. The pumping pressure load is more complicated and is usually determined by factors such as the parameters of the concrete pumping equipment and the pipeline layout. It is generally calculated based on experience or consulting the manufacturer of the equipment according to a certain pressure value acting on the contact area between the pipeline and the formwork. Finally, the above loads are superimposed to obtain the total construction load, and then the total construction load is added to the constant load to obtain the preload.

[0037] The water load unit simulates the dead load and construction load on the bridge, that is, the weight of the water load unit is the preload value. According to the preload value and the structural size of the bridge, the size of the water bag 200 and the weight of each water bag 200 are determined, which are used as standardized water bags 200 to determine the number of water bags 200 required, and the water bags 200 are modularized to facilitate accurate control of loading and unloading. Among them, each water bag 200 must be filled with water in advance to determine the amount of water filled, which generally shall not be greater than 80% of the full load of the water bag 200, that is, a margin is left in the water bag 200 as a buffer to prevent the water volume from expanding and causing rupture. In addition, it can also protect the structure of the water bag 200 and extend the service life of the water bag 200.

[0038] In an embodiment of the present invention, the bridge has a plurality of box girders 300 arranged along its length direction, the top two sides of the box girder 300 are respectively provided with a first ballast 310 and a second ballast 320, and at least one between the first ballast 310 and the second ballast 320 and inside the box girder 300 is provided with a loading area 100.

[0039] Specifically, the main structure of the bridge is a box girder 300, and multiple box girders 300 are arranged along the length direction of the bridge. The figure shows the cross section of the box girder 300. The box girder 300 has a storage space inside. The two sides of the top of the box girder 300 serve as the first roadbed 310 and the second roadbed 320. After the preloading on the box girder 300 is stable, concrete is poured on the first roadbed 310 and the second roadbed 320, and the water bag 200 is unloaded at the same time to keep the load on the box girder 300 stable. The storage space between the first roadbed 310 and the second roadbed 320 and inside the box girder 300 is The space between the first and second ballast beds 310 and 320 is used as a loading area 100 for placing water-bearing units. Since the interior of the box girder 300 is more inconvenient to take out and put in than the top of the box girder 300, the water-bearing units are preferentially placed in the loading area 100 between the first ballast bed 310 and the second ballast bed 320, so as to facilitate the placement of the water-bearing units and the removal of water bags 200 of corresponding weight during pouring, and facilitate operation. When the weight of the water-bearing units that can be placed in the loading area 100 between the first ballast bed 310 and the second ballast bed 320 cannot meet the preload value, the water-bearing units are placed in the loading area 100 inside the box girder 300.

[0040] In detail, a plurality of water bags 200 are horizontally arranged in the accommodation space inside the box girder 300, and the water bags 200 are fully arranged in the longitudinal height of the box girder 300 and in the length direction of the bridge, so that the pressure on the box girder 300 is balanced, and by stacking the water bags 200 in the longitudinal direction, not only the expected pre-compression effect can be achieved, but also the contact area of ​​the water bags 200 on the box girder 300 can be effectively reduced, thereby facilitating other operations.

[0041] In an embodiment of the present invention, the bridge loading preloading system further includes a support member 400 , and the support member 400 is disposed in the loading area 100 to limit the water load unit.

[0042] Specifically, the support member 400 adopts an angle steel bracket, the support member 400 is set in the loading area 100, and the water load unit is placed in the support member 400, so as to fix the water load unit through the support member 400, which can ensure that the load can be pre-designed in loading order, position, and precise positioning, so that the simulated loading and unloading effects are closer to the calculated values.

[0043] In the embodiment of the present invention, a plurality of support members 400 are provided, and at least one water bag 200 is disposed in each support member 400 .

[0044] Specifically, inside the box beam 300, a support member 400 is placed horizontally, and multiple water bags 200 are placed in each support member 400. The multiple water bags 200 are not only placed in sequence in the horizontal direction, but also stacked vertically, so that the water bags 200 can be accurately positioned. Partitions are provided between the multiple water bags 200 placed horizontally on each support member 400 to separate adjacent water bags 200.

[0045] In an embodiment of the present invention, the bridge preloading system further includes an observation device 500, which is disposed on the top of the box girder 300 and is used to observe deformation data after preloading.

[0046] Specifically, the observation device 500 is set at the top of the box girder 300. During the preloading process and when the box girder 300 is preloaded, the height before and after the preloading is observed by the observation device 500 to obtain the deformation data of the box girder 300 after the preloading, which generally refers to the settlement in the vertical direction. When the deformation data is less than 1 mm within a certain period of time, it is regarded as a stable state, and the next step of operation is carried out. Generally, data within 24 hours are selected. In detail, the preloading includes multiple levels of preloading, and the preloading value of each level is determined according to the percentage of the preloading load value. After each level of preloading is completed, the deformation data is observed by the observation device 500. When it is stable, the next level of preloading is carried out.

[0047] The observation device 500 uses a GNSS displacement detector.

[0048] In the embodiment of the present invention, a first observation point is respectively set at the middle of the side span and the middle span and at 1 / 4 of the span of the bridge, and each first observation point is provided with a group of observation devices 500.

[0049] Specifically, first observation points are set at key stress and deformation areas of the bridge, generally at the side span, middle span and quarter points. A group of observation devices 500 are set at each first observation point to observe the settlement, i.e., deformation data. Specifically, an observation rod or settlement plate is fixed at each first observation point, and the observation device 500 is installed through the observation rod or settlement plate to measure the settlement in the vertical direction.

[0050] In the embodiment of the present invention, at least one second observation point is provided between any two adjacent first observation points, and a group of observation devices 500 is provided at each second observation point.

[0051] Specifically, at least one second observation point is set between any two adjacent first observation points, so that the distance between any first observation point and the adjacent second observation point or between any second observation point and its adjacent second observation point is less than 20m, which is convenient for comprehensively evaluating the deformation data of the box girder 300 and accurately monitoring the settlement.

[0052] In an embodiment of the present invention, the first observation point and the second observation point respectively include two observation sub-points, and the two observation sub-points are symmetrically arranged in the width direction of the bridge.

[0053] Specifically, the first observation point and the second observation point are arranged along the length direction of the bridge. On the cross section of the box girder 300, the first observation point and the second observation point respectively include two observation sub-points. The two observation sub-points are symmetrically arranged on the left and right sides of the cross section of the box girder 300 to comprehensively observe the deformation characteristics of the box girder 300 and the foundation.

[0054] The present invention also provides a bridge load preloading method, comprising the following steps:

[0055] S10, erecting the box girder 300: the box girder 300 is arranged along the length of the bridge, the two sides of the top of the box girder 300 are respectively the first track bed 310 and the second track bed 320, and the area between the first track bed 310 and the second track bed 320 and the inside of the box girder 300 are used as the loading area 100;

[0056] S20, preloading: the preloading load value is calculated according to the second-phase constant load and the construction load of the bridge, and the number and size of the required water bags 200 are calculated according to the preloading load value, and the water bags 200 filled with water are placed in the loading area 100;

[0057] S30, observation: first observation points are respectively set at the side span, middle span and 1 / 4 span of the bridge, at least one second observation point is set between adjacent first observation points, and an observation device 500 is set at each first observation point and second observation point to observe the deformation and settlement value of the bridge;

[0058] S40, pouring: pouring is performed on the first track bed 310 and the second track bed 320, and the water bags 200 with equal load weight in the loading area 100 are unloaded according to the weight of the pouring until the water bags 200 are completely unloaded.

[0059] In the technical solution of the present invention, during the erection of the box beam 300, a plurality of box beams 300 are arranged along the length direction of the bridge, and the first ballast bed 310 and the second ballast bed 320 on both sides of the top of the box beam 300 are used as the casting area. After the box beam 300 is erected, the weight of the required ballastless track is calculated according to the length of the bridge, that is, the weight of the structures such as the ballast plate, rails, steel bars, sleepers, fasteners and bridge deck system. For example, the weight of the ballast plate per meter is obtained by multiplying its required width and height per meter of length and combining its density, and then combining the total length of the bridge to obtain the weight of the required ballast plate, and the weight of the rail is calculated by multiplying the weight of the rail per meter by The total weight of the required rails is obtained from the total length of the bridge. The calculation of steel bars, sleepers, fasteners and bridge decks is the same as above. The required second-phase constant load is calculated by multiplying the load weight per meter by the total length of the bridge, and then the construction load is calculated. Specifically, the construction load includes but is not limited to the dynamic load generated by construction personnel walking on the working surface, operating tools and small construction equipment (such as vibrators), or when pumping concrete, the pressure generated during the pumping process is transmitted to the support system through the delivery pipe. Therefore, its weight calculation is also divided into multiple parts, such as construction personnel load and equipment load. The construction personnel load is usually calculated at 2.5kN / m per person. 2 Calculation: If the construction area is A square meters, the construction personnel load is 2.5A Newtons. The equipment load needs to be calculated based on the type and weight of the equipment used. For example, small equipment such as vibrators can generally be considered at 1kN per unit, while larger equipment is calculated based on its actual weight and area of ​​action. The impact load of concrete pouring also needs to be considered, because concrete pouring will generate an impact load, which can generally be taken as 2kN / m 2If the dumping area is B square meters, the impact load is 2B Newtons. Then there is the concrete pumping pressure load. The pumping pressure load is more complicated and is usually determined by factors such as the parameters of the concrete pumping equipment and the pipeline layout. It is generally calculated based on experience or consulting the manufacturer of the equipment according to a certain pressure value acting on the contact area between the pipeline and the formwork. Finally, the above loads are superimposed to obtain the total construction load. The second-phase constant load is added to the construction load to obtain the preload. According to the preload, the size of the box girder 300 and the size of the water bag 200 to be used, the number of water bags 200 is determined, and the water bags 200 are placed in the loading area 100 as the preload. By setting an observation device 500 on the bridge, the changes of the box girder 300 during the preload process are observed. Shape data, after the preload is stable, the box girder 300 is poured. Specifically, when the first roadbed 310 and the second roadbed 320 are poured, the water bag 200 with equal load weight is removed according to the weight of the poured concrete, so that the load on the box girder 300 remains stable until the water bag 200 is completely unloaded. Among them, the water bag 200 occupies a small space when not filled with water, is light in weight, and is easy to transport. The water bag 200 can be reused, which reduces the cost of materials and the damage to the environment by solid waste. In addition, a plurality of water bags 200 filled with the same weight of water are provided, and the water bags 200 are modularized to facilitate the adjustment of the loading and unloading weights, thereby achieving precise control of the preload and convenient operation, and avoiding deformation and settlement of the bridge caused by excessive loads and sudden changes.

[0060] In an embodiment of the present invention, the preloading includes multi-stage loading, and the settlement of the bridge is observed after each stage of loading is completed. When the settlement per 24 hours is less than or equal to 1 mm, the next stage of loading is performed until all loading is completed.

[0061] Specifically, the preloading of the box girder 300 includes multi-level loading, generally using five-level preloading or four-level preloading, for example, the four-level preloading is 0→20%→50%→80%→100%. At this time, the specific graded preloading value is selected according to the actual preloading coefficient according to the actual needs, and the order of preloading is generally from the middle span to the side span. After each stage of preloading is completed, the box girder 300 needs to be observed, and the observation time for each stage is not less than 24 hours. When the daily settlement of each stage is less than 1 mm, the box girder 300 is stable and the next stage of preloading can be carried out. When the bridge is loaded to the weight of the preloading load value, it is observed for at least two consecutive days until it is stable.

[0062] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A bridge load preloading system, It is characterized in that Used for a bridge, the bridge is provided with a loading area, the bridge loading preloading system includes a water-loading unit, the water-loading unit is arranged in the loading area, each of the water-loading units includes a plurality of water bags, and the plurality of water bags are stacked in the width direction and / or height direction of the bridge.

2. The bridge preloading system according to claim 1, It is characterized in that The bridge has a plurality of box girders arranged along its length direction, the top two sides of the box girders are respectively provided with a first ballast and a second ballast, and the loading area is provided at least one between the first ballast and the second ballast and inside the box girders.

3. The bridge preloading system according to claim 1, It is characterized in that The bridge loading preloading system also includes a support member, which is arranged in the loading area to limit the water load unit.

4. The bridge preloading system according to claim 3, It is characterized in that There are a plurality of support members, and at least one water bag is disposed in each support member.

5. The bridge load preloading system according to claim 2, It is characterized in that The bridge preloading system also includes an observation device, which is arranged on the top of the box girder and is used to observe deformation data after preloading.

6. The bridge preloading system according to claim 5, It is characterized in that A first observation point is respectively provided at the middle of the side span and the middle span and at 1 / 4 of the span of the bridge, and each first observation point is provided with a group of the observation devices.

7. The bridge preloading system according to claim 6, It is characterized in that At least one second observation point is provided between any two adjacent first observation points, and a group of the observation devices is provided at each of the second observation points.

8. The bridge load preloading system according to claim 6, It is characterized in that The first observation point and the second observation point each include two observation sub-points, and the two observation sub-points are symmetrically arranged in the width direction of the bridge.

9. A bridge preloading method, It is characterized in that The following steps are involved: Erecting box girders: The box girders are set along the length of the bridge. The two sides of the top of the box girder are the first and second ballasts respectively. The area between the first and second ballasts and inside the box girder are used as the loading area. Preloading: The preloading load value is calculated based on the second-phase dead load and construction load of the bridge, and the number and size of the required water bags are calculated based on the preloading load value. The water bags filled with water are placed in the loading area; Observation: First observation points are set at the side span, middle span and 1 / 4 span of the bridge respectively, at least one second observation point is set between adjacent first observation points, and observation devices are set at each first observation point and second observation point to observe the deformation and settlement value of the bridge; Pouring: Pour the first and second track beds, and unload the water bags with equal load weight in the loading area according to the weight of the pouring until the water bags are completely unloaded.

10. The bridge preloading method according to claim 9, It is characterized in that The preloading includes multiple levels of loading, and the settlement of the bridge is observed after each level of loading is completed. When the settlement every 24 hours is less than or equal to 1 mm, the next level of loading is carried out until all loading is completed.

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