Construction Method for River Interception of the Bracket Foundation of a Cast-in-Place Bridge across a River

Abstract

The present invention discloses a construction method for river interception of a cast-in-situ bridge support foundation across a river, which includes: determining the designed flow rate for river interception and the river interception conditions according to the average flow rate of the river per unit time; arranging a construction access road and carrying out river dredging and a rockfill dike; carrying out rockfill advancement after the dike; during the advancement construction, burying diversion pipes by means of excavation after filling; carrying out closure of the river mouth with dressed stones; after the closure of the river interception is completed, backfilling and compaction are carried out to form a cushion layer, and the river interception construction is completed. According to the solution of the present invention, the construction cost of the project can be saved; it has the advantages of wide applicability of the construction scope, short construction period, safety and reliability, and convenient operation. At the same time, after the support is demolished, the filled slag can be used as backfill material for the abutment and recycled, saving materials and being environmentally friendly, which conforms to the current industrial policy. The social benefits are remarkable, and it has broad application value and popularization prospects.

Description

Technical Field

[0001] The invention relates to the technical field of riverbed interception in the construction of a superstructure of a cross-river cast-in-place bridge in transportation and municipal engineering, and in particular to a river channel interception construction method for a cross-river cast-in-place bridge support foundation. Background Art

[0002] As my country's economic and social development continues to accelerate, public infrastructure has been comprehensively built, roads and bridges have been widely built, and many high, large and special bridges have gradually emerged. However, in the field of rural road construction, the bridge form is still mainly cast-in-place beam-slab bridges and arch bridges, which cross rivers, streams, or gullies to improve residents' travel and traffic safety.

[0003] The design of this type of bridges is mainly small and medium-sized bridges, crossing rivers, streams, or gullies. The construction sites are relatively remote with poor transportation, which cannot meet the needs of large-scale construction machinery entering the site. Therefore, construction techniques such as cast-in-place scaffolding and earth-cow fetal membrane are selected.

[0004] For the construction of the superstructure of cast-in-place small and medium-sized bridges across rivers, the most mechanized construction method is the steel pipe column + Bailey beam support method. In this method, the foundation construction of the steel pipe column requires cofferdam construction or mechanical pipe sinking operation, which is difficult to organize mechanically. The traditional method requires the organization of more machinery to enter the site for operation, which is difficult to implement in remote areas with inconvenient transportation at the construction site of rural roads and bridges, or the construction cost is high. Summary of the invention

[0005] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a river diversion construction method for a cross-river cast-in-place bridge support foundation.

[0006] To achieve the above object, the present invention provides a river channel interception construction method for a cross-river cast-in-place bridge support foundation, comprising:

[0007] Determine the design flow rate of diversion and the diversion conditions based on the average flow rate per unit time of the river;

[0008] Arrange construction access roads and carry out river dredging and slag embankment;

[0009] After the embankment is built, rubble is introduced;

[0010] During the occupation construction period, the diversion pipe is buried by excavation after filling;

[0011] Carry out stone interception and closure at the river mouth;

[0012] After the diversion and closure are completed, backfill and compaction are carried out to form a cushion layer to complete the river diversion construction.

[0013] According to one aspect of the present invention, it further includes: detecting the compactness of the cushion layer and erecting a bracket on the cushion layer.

[0014] According to one aspect of the present invention, the determination of the river closure conditions includes: determining the river closure materials and quantities, arranging the river closure site and equipment, predicting the river closure parameters such as the width of the river mouth of the river course, and selecting the river closure materials and volumes according to the throttling parameters.

[0015] According to one aspect of the present invention, the construction access road is formed by backfilling with stone slag and laying a crushed stone surface layer and compacting it.

[0016] According to one aspect of the present invention, the stone slag cofferdam is to build a dam into the river bed on one or both sides of the river bed, and after filling with stone slag, equipment is used for the cofferdam.

[0017] According to one aspect of the present invention, the stone slag advance includes:

[0018] Advance in the non-river mouth section;

[0019] Construction of the wrap-around head;

[0020] Determine the elevation position of the top of the temporary cross-section of the river closure cofferdam.

[0021] According to one aspect of the present invention, the advance in the non-river mouth section is as follows:

[0022] The non-river mouth sections on the left and right banks of the river closure are simultaneously pre-advanced, and the waste slag generated is transported to the end of the cofferdam. The unloading is carried out according to the end-advance method throughout the process, and the embankment head is fully filled.

[0023] According to one aspect of the present invention, the construction of the wrap-around head is as follows:

[0024] During the construction of the advance in the non-river mouth section, if there is a loss of the materials thrown at the embankment head, the upstream of the front of the embankment head advance is preferentially treated, and throwing treatment measures are taken at this place to form a protective pick angle. Under this condition, an appropriate amount of stone slag is filled and thrown on the downstream side of the cofferdam axis, and anti-scour wrap-around head protection measures are taken.

[0025] According to one aspect of the present invention, the elevation position of the top of the temporary cross-section of the river closure cofferdam is within the range of 1 to 1.5 m above the water surface elevation.

[0026] According to one aspect of the present invention, the closure of the stone block river closure includes: construction of the wrap-around head at the river mouth and construction of the river mouth section.

[0027] According to one aspect of the present invention, the construction of the wrap-around head at the river mouth is to protect the embankment head in all directions through a reinforced stone cage.

[0028] According to one aspect of the present invention, the construction of the river mouth section is carried out by gradually advancing from both banks of the river course towards the middle.

[0029] According to one aspect of the present invention, the backfill compaction is carried out in layers with a thickness of 300 - 500 mm and compacted by a roller.

[0030] According to one aspect of the present invention, the concrete cushion is a C20 concrete cushion with a thickness of 150 mm.

[0031] According to the solution of the present invention, it is convenient to operate: adapting to local conditions, the technology of river closure construction is simple to operate and low in cost. Safe and reliable: The backfill of the support foundation adopts the river closure construction method and the river closure construction technology, which can ensure the construction safety. Flexible in application: It is applicable to the construction of all small and medium-sized bridge cast-in-place support foundations across rivers, especially the rural road construction where large machinery cannot reach, and generally there is no navigation requirement for the rivers crossed by small and medium-sized bridges. It has remarkable social benefits. The construction is simple and fast, which can shorten the construction period. Save materials and reduce consumption: During the construction period, the water flow of the river passes through the diversion pipe, and there is no need to separately build a cofferdam and conduct construction diversion. After the support is demolished, the river channel filling slag is cleaned up, and the filling slag can be used as the backfill of the abutment, which can truly save materials and be environmentally friendly.

[0032] According to the solution of the present invention, the present invention uses the river closure technology of water conservancy and hydropower to solve the construction of small and medium-sized bridges in the municipal and highway fields, and uses the river closure technology to solve the backfill problem of the support foundation of the cast-in-place cross-river bridge. The method of the present invention can be used for the support foundation construction of the support method for small and medium-sized cross-river cast-in-place bridges, especially applicable to the bridge projects of rural road construction and the construction of cross-river cast-in-place bridges in places with inconvenient transportation.

[0033] In summary, the method of the present invention can save the construction cost of the project; it has the advantages of flexible application scope, short construction period, safe and reliable, and convenient operation. At the same time, after the support is demolished, the filling slag can be used as the backfill material of the abutment, recycled and reused, saving materials and being environmentally friendly, which conforms to the current industrial policy. It has remarkable social benefits and broad application value and popularization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematically shows a flowchart of a river closure construction method for the support foundation of a cross-river cast-in-place bridge according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] Now the content of the present invention will be described with reference to exemplary embodiments. It should be understood that the described embodiments are only for enabling those of ordinary skill in the art to better understand and thus implement the content of the present invention, rather than implying any limitation to the scope of the present invention.

[0036] As used herein, the term "comprising" and its variants are to be construed as open-ended terms meaning "including but not limited to". The term "based on" is to be construed as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be construed as "at least one embodiment".

[0037] Figure 1 Schematic representation of a flow chart of a river-crossing cast-in-situ bridge support foundation river interception construction method according to an embodiment of the present invention, as Figure 1 shown. In this embodiment, the river-crossing cast-in-situ bridge support foundation river interception construction method includes the following steps:

[0038] a. Determine the interception design flow rate and the interception conditions according to the average flow rate of the river channel per unit time;

[0039] b. Arrange the construction access road and carry out river channel dredging and rockfill dike;

[0040] c. After the dike is formed, carry out rockfill advance;

[0041] d. During the advance construction, bury the diversion pipe by the method of excavation after filling;

[0042] e. Carry out stone interception and closure at the river mouth of the river channel;

[0043] f. After the interception and closure are completed, carry out backfilling and compaction to form a cushion layer to complete the river channel interception construction.

[0044] According to an embodiment of the present invention, in the above step a, the water balance method is used to calculate the interception hydraulic power: during the interception process, the upstream incoming water volume (i.e., the interception design flow rate) will be divided through the river mouth, seepage through the dike, and the water diversion structure, and a part of it will be stored in the reservoir. If the reservoir capacity is not large, the water volume stored in the reservoir can be ignored. For end dumping, as a safety factor, the seepage flow rate through the dike can also be ignored. Generally, during the closure process, the interception design flow rate consists of four parts:

[0045] Q = Q + Q d + Q s + Q ac

[0046] In the formula: Q is the flow rate at the river mouth, Q d is the diversion flow rate (the flow rate passing through the diversion), Qs is the regulated flow rate in the upstream river channel; Qac is the seepage flow rate through the dike;

[0047] The flow rate at the river mouth is calculated according to the broad-crested weir formula:

[0048]

[0049] In the formula: is the average water-crossing width at the river mouth; H0 is the water head upstream of the river mouth, and m is the discharge coefficient;

[0050] Among them, When Z / H0 is less than 0.3, for submerged flow, m = 0.385;

[0051] Z / H0 is greater than or equal to 0.3, which is non-submerged flow.

[0052] In this embodiment, the flow rate calculation formula of the dragon mouth can be obtained from the continuity equation:

[0053]

[0054] Wherein, V is the average flow velocity of the Longkou calculation section; h is the water depth of the Longkou calculation section (measured from the top of the bottom protection).

[0055] Furthermore, in this embodiment, determining the interception conditions includes: determining the interception materials and quantity, arranging the interception site and interception equipment, estimating the interception parameters of the river mouth width, and selecting the interception materials and volume according to the throttling parameters. In this embodiment, before interception, interception materials of various sizes or weights and their quantities can be prepared in a planned and purposeful manner, the site layout of the interception site can be planned, and lifting and transportation equipment can be selected; when intercepting, interception parameters of different mouth widths can be estimated in advance, and what size or weight of interception materials and their volume should be thrown when and where.

[0056] In this embodiment, the interception material is selected: slag material or slag mixture is selected, and the selection can be made according to the calculation and reference to the following Table 1.

[0057] River closure materials Applicable flow velocity (m / s) Earth material 0.5～0.7 20 - 30 kg heavy stone 0.8～1.0 50 - 70 kg heavy stone 1.2～1.3 Burlap bag filled with soil (0.7m×0.4m×0.2m) 1.5

[0058] Table 1

[0059] Furthermore, in this embodiment, in the above step a, pre-occupation work is also included: the effect of the dike occupation construction is greatly affected by the on-site hydrological conditions, and it is necessary to organize the pre-occupation work 15 to 20 days in advance based on the water situation forecast information. On this basis, the dike head is protected by reinforced gabions to create good conditions for the dragon mouth closure.

[0060] Furthermore, according to an embodiment of the present invention, in the above step b, the construction access road is formed by backfilling with slag, and is generally used after laying a crushed stone surface layer and compacting it. The construction length is determined according to the actual situation on site.

[0061] Two lanes are adopted to provide sufficient space for vehicles to pass, and the heavy lane is mainly used for the transportation of large-scale materials, such as large stones, special interception materials, etc. In order to ensure the safety of vehicles on the dike, the distance between the wheel rim of the car and the edge of the dike must be strictly controlled. The value should be at least 2.5m, and it must be well marked.

[0062] The silt and soft soil on the riverbed bank should be removed. Use a backhoe excavator to directly dig out the riverbed silt and debris, and then use a dump truck to transport the debris to the unloading point.

[0063] After the dredging within the construction scope is completed, build dikes into the riverbed on one or both sides of the riverbed first, and use dump trucks to fill with stone slag, and loaders or bulldozers to build the dikes.

[0064] Further, according to an embodiment of the present invention, in the above step c, on one side or both sides of the riverbed, throw and fill the river closure material into the riverbed to form a dike and narrow the riverbed. Specifically, in this embodiment, the stone slag advancing includes:

[0065] Advancing in the non-dragon mouth section;

[0066] Construction of the wrap-around head;

[0067] Determine the elevation position of the temporary cross-section dike crest of the river closure dike.

[0068] In this embodiment, the advancing in the non-dragon mouth section is the simultaneous pre-advancing of the left and right banks of the river closure. The equipment used is excavators and loaders. The waste slag generated is transported by dump trucks and uniformly stacked at the end of the dike. The whole process is unloaded according to the end-advancing method, and the dike head is fully thrown.

[0069] Generally, the drop of the dragon mouth of the river crossed by small and medium-sized bridges is relatively small, and it is uniformly thrown along the whole front of the dike. In addition, reasonably increase the width of the dike head according to the actual situation, aiming to create good conditions for the large-scale construction of the river closure at the dragon mouth later.

[0070] In this embodiment, the construction of the wrap-around head is as follows: During the construction of the advancing in the non-dragon mouth section, the on-site situation should be strengthened for observation. If there is a loss of the thrown materials at the dike head, the upstream of the advancing front of the dike head should be preferentially treated, and throwing treatment measures should be taken at this place to form a pick angle and play the protective role of this part. Under this condition, throw an appropriate amount of stone slag to the downstream side of the dike axis. If the situation is special, anti-scour wrap-around head protection measures are also required.

[0071] In this embodiment, during the advancing construction, crushed stones are laid trailing on the top of the dike, and special personnel are arranged to do a good job in on-site supervision and maintenance. Pay close attention to the elevation of the temporary cross-section dike crest of the river closure dike, and take corresponding prevention and control measures, requiring it to always be stable within the range of 1 - 1.5 m above the water surface elevation.

[0072] Further, according to an embodiment of the present invention, in the above step d, during the construction of the non-dragon mouth advancing section, the diversion pipe is buried by the method of excavation after filling. Generally, cement pipes are used for burial, and the top of the pipe should be backfilled with sandy gravel soil to prevent the pipe fittings from being crushed.

[0073] Further, according to an embodiment of the present invention, in the above step e, the stone interception and closure includes: dragon mouth wrapping construction and dragon mouth section construction. In this embodiment, during the dragon mouth wrapping construction, after the interception dike pre-occupation operations are in place, the dike head needs to be effectively protected by reinforced gabions, but under the condition of the dragon mouth narrowing, the flow rate will be significantly increased, so the actual scouring situation needs to be considered, and the number of thrown reinforced gabions can be increased to achieve all-round protection of the dike head.

[0074] In this embodiment, during the construction of the Longkou section, the single-walled dike is used for bidirectional blocking to achieve effective interception, following the basic principle of occupying the left and right banks at the same time; during the construction of the Longkou section, it is divided into multiple specific areas, all of which are gradually advanced from the left and right banks to the middle.

[0075] Each material convoy drove in an orderly manner, each with a flag of a specific color, and was reasonably dispatched by the on-site commander at the dike head to complete the unloading operation efficiently. It is appropriate to throw large stones by car. Considering the requirements of the project construction for the throwing strength, it is necessary to take the stability of the dike head as the main basis and reasonably optimize the throwing method of the dike head aggregate. Bulldozers can be used to rush and throw materials in some sections.

[0076] The dike dumping construction integrates multiple methods. In addition to the conventional direct dumping, centralized pushing dumping and unloading impact dumping are also used.

[0077] Furthermore, according to one embodiment of the present invention, the above method also includes slope treatment and testing the compaction of the cushion layer, and setting up a bracket on the cushion layer. In this embodiment, the natural slope requirement is considered when throwing materials, and two standards of 1:1.5 and 1:2.0 are specifically adopted. The slope is built with bagged sand, and the water-facing surface is covered with woven cloth (color strip cloth) for anti-seepage and covered with bagged sand. When the bagged sand is built, it must be arranged densely and neatly.

[0078] After the interception and closure are completed, backfill with slag or gravel soil according to the designed elevation of the support, in layers of 300-500mm thickness, and compacted with a roller.

[0079] After backfilling to the designed height, pour a 150mm thick C20 concrete cushion as the foundation of the support. The backfill height is generally more than 1.5m above the water surface, and it can be appropriately increased according to the water flow during construction in the rainy season.

[0080] The compaction degree of the foundation is tested, and the acceptance of the support foundation is organized. After passing the acceptance, it can be used as a support foundation.

[0081] It should be noted that the river closure in the present invention is not equivalent to that in water conservancy projects. The purpose of the river closure in the present invention is to obtain a support foundation, and the support foundation has special requirements for the backfilling quality and technology of the soil (slag) backfill above the water surface, especially in the range of 800 - 1000 mm below the surface layer. At the same time, diversion pipes need to be buried.

[0082] According to the above solution of the present invention, it is convenient to operate: adapting to local conditions, the technology of river closure construction is simple to operate and low in cost. Safe and reliable: The backfilling of the support foundation adopts the river closure construction method, and the river closure construction technology can ensure the construction safety. Flexible in application: It is applicable to the construction of all cast-in-place support foundations for medium and small bridges crossing rivers, especially for the construction of rural roads where large machinery cannot reach. Generally, the rivers crossed by medium and small bridges have no navigation requirements. It has remarkable social benefits. The construction is simple and fast, which can shorten the construction period. Saving materials and reducing consumption: During the construction period, the water flow in the river passes through the diversion pipes, so there is no need to build a separate cofferdam and conduct construction diversion. After the support is removed, the riverbed fill is cleared, and the fill can be used for backfilling behind the abutment, which can truly save materials and be environmentally friendly.

[0083] According to the solution of the present invention, the present invention applies the river closure technology in water conservancy and hydropower to solve the construction of medium and small bridges in the municipal and highway fields, and uses the river closure technology to solve the backfilling problem of the support foundation of cast-in-place cross-river bridges. The method of the present invention can be used for the construction of the support foundation of the support method for cast-in-place medium and small cross-river bridges, and is especially suitable for the construction of bridge projects on rural roads and the construction of cast-in-place cross-river bridges in places with inconvenient transportation.

[0084] In summary, the method of the present invention can save the construction cost of the project; it has the advantages of wide application range, short construction period, safety and reliability, and convenient operation. At the same time, after the support is removed, the fill can be used as backfill material behind the abutment, recycled, save materials and be environmentally friendly, which conforms to the current industrial policy. It has remarkable social benefits and broad application value and promotion prospects.

[0085] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of the present invention and are not restrictive. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. Construction method for river interception of the support foundation of a cast-in-situ bridge across a river, characterized in that, include: Determine the design flow rate of diversion and the diversion conditions based on the average flow rate per unit time of the river; Arrange construction access roads and carry out river dredging and slag embankment; After the embankment is built, rubble is introduced; During the occupation construction period, the diversion pipe is buried by excavation after filling; Carry out stone interception and closure at the river mouth; After the closure is completed, backfill and compaction are carried out to form a cushion layer to complete the river closure construction; The slag occupation includes: The non-Longkou section is occupied; Wrap-around construction; Determine the top elevation of the temporary cross-section of the dike; The non-Longkou section is occupied as follows: The non-Longkou sections on the left and right banks of the closure are pre-occupied at the same time, and the waste slag generated is transferred to the end of the dike. The whole process is unloaded according to the end-in method, and the dike head is fully thrown; The wrapping construction is as follows: During the occupation of the non-Longkou section, if there is loss of material thrown from the dike head, priority should be given to the upstream of the dike head occupation front, where throwing measures should be taken to form a protective angle. Under this condition, a proper amount of slag should be thrown to the downstream side of the axis of the dike head, and anti-impact head protection measures should be taken.

2. The river-crossing in-situ bridge support foundation river interception construction method according to claim 1, wherein, Also includes: The compaction degree of the cushion layer is detected, and a support is set up on the cushion layer.

3. The river-crossing cast-in-situ bridge support foundation river interception construction method according to claim 1, characterized in that, The determination of the interception conditions includes: determining the interception materials and quantity, arranging the interception site and interception equipment, estimating the interception parameters of the river mouth width, and selecting the interception materials and volume according to the throttling parameters.

4. The river-crossing cast-in-situ bridge support foundation river interception construction method according to claim 1, wherein, The construction access road is formed by backfilling with slag and laying a crushed stone surface layer and compacting it.

5. The river-crossing cast-in-situ bridge support foundation river interception construction method according to claim 1, characterized in that, The slag embankment is to build an embankment on one side or both sides of the riverbed into the riverbed, and the embankment is built after filling with slag.

6. The river-crossing cast-in-situ bridge support foundation river interception construction method according to claim 1, characterized in that, The temporary cross-section top elevation of the dike is within the range of 1 to 1.5 m above the water surface elevation.

7. The river-crossing in-situ bridge support foundation river interception construction method according to claim 1, characterized in that, The material stone interception and closure includes: Longkou head wrapping construction and Longkou section construction.

8. The construction method for river interception of the cast-in-situ bridge support foundation across the river according to claim 7, characterized in that, The Longkou head wrapping construction is to protect the embankment head in all directions through reinforced gabions.

9. The river-crossing in-situ bridge support foundation river interception construction method according to claim 7, characterized in that, The construction of the Longkou section is carried out gradually from both sides of the river to the middle.

10. The river-crossing cast-in-situ bridge support foundation river interception construction method according to claim 1, wherein, The backfill is compacted in layers of 300-500 mm thickness using a roller.

11. The river-crossing cast-in-situ bridge support foundation river interception construction method according to claim 1, characterized in that, The cushion layer is a 150 mm thick C20 concrete cushion layer.

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