Double-row PLC construction method pile cofferdam and steel trestle combined construction method for over-deep pit pond

Abstract

The invention relates to the technical field of trestle construction, in particular to a double-row PLC construction method pile cofferdam and steel trestle combined construction method for an over-deep pit pond. Comprising the steps of construction preparation; positioning and hitting are carried out according to construction requirements; construction method piles are applied; parallelly connecting the piles; pulling an anchor; filling soil by a water driving method; mounting a bearing cross beam and a bailey beam; paving a bridge floor; and the steps are repeated until the construction of the pile cofferdam is completed. After construction is completed, the steel trestle is dismantled; a drainage well is further arranged, and the distance between the next dewatering well and the current dewatering well is determined according to the function f (T) and the function f (h). Compared with the prior art, the method has the beneficial effects that the dewatering well is arranged in the cofferdam, and the layout of the dewatering well is determined according to the actual condition of construction, so that the soil moisture content is effectively reduced, the effective stress of soil is increased, the stability of a soil body in the cofferdam is ensured, and the safety of subsequent construction is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of trestle construction, and in particular to a combined construction method of a double-row PLC method pile cofferdam and a steel trestle for a deep pond. Background Art

[0002] When a new urban road passes through a fish pond, a temporary retaining structure such as a cofferdam is needed to separate the road construction area to prevent water and soil from entering the construction site so that drainage and foundation pit excavation can be carried out in the cofferdam. At present, double-row steel sheet piles or PLC method pile cofferdams are often used in the construction of roads passing through fish ponds in my country. However, if the pond is deep, the pile driver model required will be higher, and the corresponding pile driver will occupy a larger area. The driving of double-row PLC method piles needs to be carried out on a steel trestle.

[0003] China Rights Publication No. CN 110847169 A discloses a construction method for a steel pipe pile steel trestle, including: step one, making steel pipe piles; step two, installing an assembled cantilever guide frame positioning device; step three, putting steel pipe piles in place; step four, vibrating pile sinking; step five, installing pile-to-pile flat joints; step six, pillow beam construction; step seven, circumferential ear plate construction; step eight, Bailey main beam construction; step nine, I-beam distribution beam and bridge deck construction; step ten, upper system preloading construction. It can be seen that the construction method of the steel pipe pile steel trestle has the following problems: during the construction process, it is necessary to install equipment such as an assembled cantilever guide frame positioning device, and the period required for changing direction in the later stage is relatively long, and the two rows of steel pipe piles in the middle of the trestle need to be held by a floating crane, which can easily cause unnecessary shaking of the steel sheet piles, affecting the firmness of the piles and the safety of subsequent construction. Summary of the invention

[0004] The purpose of the present invention is to provide a combined construction method of double-row PLC method pile cofferdams and steel trestle bridges for deep ponds, so as to solve the problems in the related art that the construction period is long and the construction safety cannot be guaranteed.

[0005] To this end, the present invention provides a combined construction method of a double-row PLC method pile cofferdam and a steel trestle for a deep pond, comprising:

[0006] Conduct construction preparations;

[0007] Locate the steel pipe pile construction site according to construction requirements and drive the first pair of steel pipe piles;

[0008] The construction piles are driven in the order of steel pipe piles-Larsen steel sheet piles-steel pipe piles;

[0009] After the construction method piles are sunk to the designed elevation, the piles are leveled;

[0010] Use steel bars to tie both sides together for anchoring;

[0011] Use the water-driving method to fill the pond, with the filling sequence moving from the shore to the pond;

[0012] Install load-bearing beams and Bailey beams;

[0013] Laying the bridge deck;

[0014] The next construction method pile is driven, and the steps of anchoring, water-driving construction, installation of load-bearing beams, and Bailey beams for laying the bridge deck are continued until the construction of the construction method pile cofferdam is completed;

[0015] After the construction is completed, the steel trestle will be removed;

[0016] Among them, after the construction of the water-driving method, a drainage well is set in the middle position of the parallel connection z on both sides. The distance between the next drainage well and the current drainage well is determined according to the depth function f(T) with the ordinate being the distance A from the shore and the abscissa being the underwater fill depth T and the function f(h) with the distance d from the previous drainage well. The first drainage well is set at 3m from the shore.

[0017] Furthermore, the interval of the drainage wells is determined according to the underwater filling depth and the permeability coefficient, and further includes:

[0018] Detect the relationship between the distance to the shore and the water depth on the current construction route;

[0019] Establish a depth function with the ordinate being the distance A from the shore and the abscissa being the depth T of the underwater fill: A = f(T);

[0020] Test the permeability coefficient k of the filled soil;

[0021] According to the permeability coefficient K, the parallel connection distance L, and the diameter R of the drainage well, a function f(H) including the unknown variables: the current underwater fill depth T and the distance d from the previous drainage well is established;

[0022] The function f(T) and the function f(H) are combined to obtain the actual distance d0 between the next precipitation well and the current precipitation well.

[0023] Furthermore, the calculation method of the distance d between the next precipitation well and the current precipitation well is:

[0024] Obtain various parameters during the construction process: permeability coefficient K, parallel connection spacing L, dewatering well diameter R, current underwater fill depth T;

[0025] Substitute the various parameters obtained during the construction process into the formula in numerical form: Among them: d is the distance between the next precipitation well and the current precipitation well, the permeability coefficient K, the parallel connection distance L, the precipitation well diameter R, and the current underwater fill depth H.

[0026] Furthermore, the installation of the load-bearing beam further comprises the following steps:

[0027] Mark the positions of steel pipe piles on the load-bearing beams;

[0028] Lift the load-bearing beams and ensure that the marks coincide with the steel pipe piles during the lifting process;

[0029] Arc-shaped limiting steel plates are welded between the pile body and the load-bearing beam to fix the load-bearing beam.

[0030] Furthermore, the installation of the Bailey beam further comprises the following steps:

[0031] The Bailey beam is tested before entering the construction site, and after the test assembly is correct, it is assembled on site;

[0032] Before installing the Bailey beam, measurement and layout are first performed on the load-bearing beam to determine the exact position of the Bailey frame;

[0033] The Bailey beam is lifted by a crawler crane and placed at one end of the pond where the Bailey beam has been installed and in a straight line with the same;

[0034] After aligning the pin hole of the lower chord of the Bailey beam and inserting the pin bolt, lift the rear end of the Bailey beam, insert the upper chord pin body and set the safety pin.

[0035] Furthermore, after the Bailey beam is accurately positioned, it is first firmly tied to the load-bearing crossbeam, then the limiter is welded, and then another set of Bailey beams is installed, and the two sets of Bailey sheet scissors struts are connected.

[0036] Furthermore, the bridge deck used for paving the bridge deck includes two specifications, one is a 16mm thick patterned steel plate, and the other is an assembled bridge deck with a specification of 6m×2m and 3m×2m. Among them: the assembled bridge deck adopts a 138mm thick customized steel panel, the transverse rib spacing is 750mm, the longitudinal rib spacing is 250mm, and the two ends are fixed to the secondary beam with screws. At the same time, 5*50 flat steel is welded at the joint. The bridge deck steel plate adopts a patterned anti-slip steel plate and is coated with a polymer anti-slip and anti-corrosion material. The anti-corrosion material adopts polyurethane oil-resistant, and the coating thickness is 1 to 2mm.

[0037] Furthermore, the steel trestle also includes a trestle abutment, and rubber pads are arranged between the abutment and the trestle plank.

[0038] Furthermore, the load-bearing crossbeam is composed of two I45a I-beams, and the Bailey beam adopts a 321 type Bailey beam.

[0039] Furthermore, the construction preparation process specifically includes the processing and storage of steel cofferdams, wherein the steel cofferdams include: steel pipe piles, steel sheet piles, tension steel bars, and an operating platform.

[0040] Compared with the prior art, the beneficial effects of the present invention are that, on the one hand, the present invention can shorten the distance for sheet pile injection, improve the safety during construction and the success rate of sheet pile lock connection by injecting sheet pile cofferdam in water on the steel trestle erected on the double-row sheet pile cofferdam, and at the same time, the system acts as a temporary access road during road construction in the cofferdam, which can shorten the construction period of the road in the cofferdam; on the other hand, by arranging drainage wells in the cofferdam and determining the layout of the drainage wells according to the actual construction situation, the soil moisture content is effectively reduced, the effective stress of the soil is increased, the stability of the soil in the cofferdam is ensured, and the safety of subsequent construction is ensured.

[0041] Furthermore, by replacing the previous empirical coefficients with the traditional empirical calculation method through soil-related performance parameters and function constraints, the unstable drainage effect caused by personal reasons can be eliminated, and the influence of individual differences can be avoided, thereby ensuring the stability of the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flowchart of the steps of the combined construction method of double-row PLC method pile cofferdam and steel trestle for deep ponds according to an embodiment of the present invention;

[0043] Figure 2 It is a structural diagram of a combination of a double-row PLC method pile cofferdam and a steel trestle for a deep pond according to an embodiment of the present invention;

[0044] Figure 3 A flow chart of the steps for determining the interval of drainage wells according to the underwater filling depth and permeability coefficient in an embodiment of the present invention;

[0045] Figure 4 This is a flow chart of the installation steps of the load-bearing beam described in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0047] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0050] See also Figure 1 As shown, it is a flowchart of a method for combining a double-row PLC method pile cofferdam and a steel trestle for a deep pond according to an embodiment of the present invention, comprising the following steps:

[0051] Step S1, preparing for construction;

[0052] Step S2, locating the steel pipe pile construction site according to the construction requirements and driving the first pair of steel pipe piles;

[0053] Step S3, driving the construction piles in the order of steel pipe piles, Larsen steel sheet piles, and steel pipe piles;

[0054] Step S4, after the construction piles are sunk to the designed elevation, the piles are leveled;

[0055] I16a channel steel is used for the parallel connection, and the parallel connection construction is carried out at normal water level;

[0056] Step S5, using steel bars to connect the two sides and anchor them;

[0057] The anchors are anchored by steel bars with a diameter of 25 mm, connecting both sides, with an anchor spacing of 3000 mm.

[0058] Step S6, using the water-driving method to fill the soil, the filling sequence is from the shore to the pond;

[0059] Step S7, installing the load-bearing beam and Bailey beam;

[0060] Step S8, laying the bridge deck;

[0061] Step S9, driving the next construction method pile, and continuing the steps of anchoring, water-driving construction, installing the load-bearing beam, and laying the bridge deck with Bailey beams, until the construction of the construction method pile cofferdam is completed;

[0062] Step S10, after the construction is completed, the steel trestle is dismantled;

[0063] In the process of the water-driving method, the distance between the next dewatering well and the current dewatering well is determined according to the depth function f(T) whose ordinate is the distance A from the shore and whose abscissa is the depth T of the underwater fill and the function f(h) whose distance d from the previous dewatering well is determined;

[0064] The construction method piles are driven in the order of steel pipe piles-Larsen steel sheet piles-steel pipe piles in a cyclic alternating manner. Since the guide groove connecting the steel pipe piles and the Larsen steel sheet piles has limited lateral size adjustment and the guide groove is consistent with the center line of the pile row, the positioning and verticality control of the first pile are particularly critical. The pile top elevation should be strictly controlled during the construction process, and the verticality of the steel pipe piles should meet the requirement of <1%. Check the position in time, and correct or pull out and re-drive if a large tilt occurs in the initial stage of pile sinking (1m~2m); the overlap between the piles is guaranteed by the small tongue and groove construction of the Larsen steel sheet piles, so as to achieve a water-stopping effect.

[0065] See also Figure 2 As shown, it is a structural diagram of the combination of a double-row PLC method pile cofferdam and a steel trestle for a deep pond according to an embodiment of the present invention, including: steel pipe piles 1, reinforced vertical rods 2, 125A distribution beams 3, support frames 4, 3-meter Bailey beams 5, bridge decks 6, reinforced support rods 7, flat joints 8, water level lines 9, and load-bearing beams (not shown in the figure, the load-bearing beams are arranged below the 3-meter Bailey beams).

[0066] See also Figure 3 As shown, it is a flow chart of the steps of determining the interval of the drainage wells according to the present invention according to the underwater filling depth and the permeability coefficient, wherein:

[0067] Detect the relationship between the distance to the shore and the water depth on the current construction route;

[0068] Establish a depth function f(T) with the ordinate being the distance A from the shore and the abscissa being the depth T of the underwater fill, that is, A=f(T);

[0069] Test the permeability coefficient k of the filled soil;

[0070] According to the permeability coefficient K, the parallel connection distance L, and the diameter R of the drainage well, a function f(H) is established, which includes two unknowns: the current underwater fill depth T and the distance d from the previous drainage well;

[0071] Among them: The purpose of the present invention is to reduce the water content in the soil after the water-driving method is used to increase the stability of the trestle during the subsequent construction process, so the underwater filling depth is consistent with the depth of the precipitation well;

[0072] According to the above relationship, the distance from the next precipitation well to the shore = the distance from the current precipitation well to the shore + the distance d between the next precipitation well and the current precipitation well. By combining the function f(T) and the function f(H), the actual distance d0 between the next precipitation well and the current precipitation well can be obtained.

[0073] Specifically, the calculation method of the distance d between the next precipitation well and the current precipitation well is:

[0074] Obtain various parameters during the construction process: permeability coefficient K, parallel connection spacing L, dewatering well diameter R, current underwater fill depth T;

[0075] Substitute the various parameters obtained during the construction process into the formula in numerical form: Among them: d is the distance between the next precipitation well and the current precipitation well, the unit is m, the permeability coefficient K is in m / s, the parallel connection distance L is in mm, the precipitation well diameter R is in mm, and the current underwater fill depth T is in m.

[0076] In the existing technology, the calculation method for the spacing between drainage wells is: d = k × h, where: d is the spacing between drainage wells (m), k is an empirical coefficient, usually between 1 and 3, and h is the depth of the drainage well (m). This method relies on the construction experience of construction personnel and is applied in the construction field where the depth of drainage wells is required to be consistent. It is not suitable for the double-row PLC method pile cofferdam and steel trestle combined construction method for over-deep ponds provided in the embodiment of the present invention;

[0077] Therefore, the present invention embodiment combines the current construction characteristics to know that the permeability coefficient K, the parallel connection spacing L, the current underwater fill depth T and the precipitation well spacing are proportional, and the precipitation well diameter R is inversely proportional to the precipitation well spacing. Substituting each value into The magnitude of the value is 10 0 -109 By using the function f(x)=3-2 / x, we can The value of falls within the interval [1,3], which is consistent with the selection range of the empirical coefficient in the prior art and eliminates the instability of the soil structure caused by precipitation due to the subjective judgment of the construction workers, thereby ensuring the safety of the construction process.

[0078] The specific implementation method is: if the currently known parameters are: the water permeability is 4×10 -7 m / s, the parallel connection spacing is 3000mm, the diameter of the precipitation well is 300mm, the distance between the current precipitation well and the shore is 15m, T=H, then the calculation process of the distance between the next precipitation well and the current precipitation well is:

[0079] Step 1: Substitute the above data into the function f(h), and we get d=(3-24 / 9×10 5 )×H;

[0080] Step 2: Substitute the relationship A=15+d (i.e., the distance from the next precipitation well to the shore is equal to the distance from the current precipitation well to the shore + the distance between the next precipitation well and the current precipitation well) into A=f(T) to obtain: 15+d=f(T);

[0081] Step 3: Substitute d obtained in step 1 into (3-24 / 9×10 5 )×H, and T=H are substituted into the formula in step 2. There is only one unknown number H in the formula. By solving it, we can get H and then get the values ​​of other parameters.

[0082] It can be known that this method has a clear functional relationship. By computer encoding the early data monitoring stage, the input parameters can be directly converted into the distance between the next precipitation well and the current precipitation well, thereby improving the construction speed while ensuring construction safety.

[0083] See also Figure 4 As shown, it is a flow chart of the installation steps of the load-bearing beam of the present invention, wherein:

[0084] Mark the positions of steel pipe piles on the load-bearing beams;

[0085] Lift the load-bearing beams and ensure that the marks coincide with the steel pipe piles during the lifting process;

[0086] Arc-shaped limiting steel plates are welded between the pile body and the load-bearing beam to fix the load-bearing beam.

[0087] Specifically, the installation of the Bailey beam also includes the following steps:

[0088] The Bailey beam is tested before entering the construction site, and after the test assembly is correct, it is assembled on site;

[0089] Before installing the Bailey beam, measurement and layout are first performed on the load-bearing beam to determine the exact position of the Bailey frame;

[0090] The Bailey beam is lifted by a crawler crane and placed at one end of the pond where the Bailey beam has been installed and in a straight line with the same;

[0091] After aligning the pin hole of the lower chord of the Bailey beam and inserting the pin bolt, lift the rear end of the Bailey beam, insert the upper chord pin body and set the safety pin.

[0092] Specifically, after the Bailey beam is accurately positioned, it is first firmly tied to the load-bearing crossbeam, then the limiter is welded, and then another set of Bailey beams is installed, and the two sets of Bailey sheet scissors struts are connected.

[0093] Specifically, the bridge deck used for laying the bridge deck also includes two specifications, one is a 16mm thick patterned steel plate, which is suitable for all steel platforms and part of the main trestle; the other is a prefabricated bridge deck with specifications of 6m×2m and 3m×2m, which is suitable for all supporting trestle bridges and part of the main trestle. The prefabricated bridge deck uses a 138mm thick customized steel panel, with a transverse rib spacing of 750mm and a longitudinal rib spacing of 250mm. Both ends are fixed to the secondary beam with screws. At the same time, 5*50 flat steel is welded at the joint to increase its strength. The bridge deck steel plate uses a patterned anti-skid steel plate and is coated with a polymer anti-skid and anti-corrosion material. The anti-corrosion material can be made of polyurethane oil-resistant, and the coating thickness is about 1 to 2mm. After the construction of the bridge deck is completed, a load test can be carried out and record materials can be formed.

[0094] Specifically, the steel trestle also includes a pier, and rubber pads are set at the abutment and the pier deck. The pier abutment adopts a reinforced concrete structure, with a size of 6.9m*3m*2.8m. Eight 400*400*10m steel plates are embedded on the abutment and welded to the Bailey plate; the foundation soil layer under the abutment needs to be compacted to ensure that the foundation bearing capacity is not less than 150Kpa, the abutment is close to the water side and is not less than 1m away from the river, and slope protection is carried out at the abutment to prevent the abutment from being unstable due to river erosion.

[0095] Specifically, the load-bearing crossbeam is composed of two I45a I-beams, and the Bailey beam adopts 321 type Bailey beam.

[0096] Specifically, the construction preparation process is specifically the processing and storage of steel cofferdams, wherein the steel cofferdams include: steel pipe piles, steel sheet piles, tension steel bars, and working platforms.

[0097] In the embodiment of the present invention, the piles are extended by factory connection or assembly site connection. The specific extension method depends on the actual situation and is not specifically limited here. Among them: the assembly site connection connects two sections of steel pipe piles into one section of steel pipe piles, and the length should be 2m above the water surface while meeting the design requirements.

[0098] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A combined construction method of double-row PLC pile cofferdam and steel trestle for crossing deep ponds, characterized in that: include: Conduct construction preparations; Locate the steel pipe pile construction site according to construction requirements and drive the first pair of steel pipe piles; The construction piles are driven in the order of steel pipe piles-Larsen steel sheet piles-steel pipe piles; After the construction method piles are sunk to the designed elevation, the piles are leveled; Use steel bars to tie both sides together for anchoring; Use the water-driving method to fill the pond, with the filling sequence moving from the shore to the pond; Install load-bearing beams and Bailey beams; Laying the bridge deck; The next construction method pile is driven, and the steps of anchoring, water-driving construction, installation of load-bearing beams, and Bailey beams for laying the bridge deck are continued until the construction of the construction method pile cofferdam is completed; After the construction is completed, the steel trestle will be removed; Among them, after the construction of the water-driving method, a drainage well is set in the middle position of the parallel connection z on both sides. The distance between the next drainage well and the current drainage well is determined according to the depth function f(T) with the ordinate being the distance A from the shore and the abscissa being the underwater fill depth T and the function f(h) with the distance d from the previous drainage well. The first drainage well is set at 3m from the shore.

2. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 1 is characterized in that: The interval of the drainage wells is determined according to the underwater fill depth and the permeability coefficient, and also includes: Detect the relationship between the distance to the shore and the water depth on the current construction route; Establish a depth function with the ordinate being the distance A from the shore and the abscissa being the depth T of the underwater fill: A = f(T); Test the permeability coefficient k of the filled soil; According to the permeability coefficient K, the parallel connection distance L, and the diameter R of the drainage well, a function f(H) including the unknown variables: the current underwater fill depth T and the distance d from the previous drainage well is established; The function f(T) and the function f(H) are combined to obtain the actual distance d0 between the next precipitation well and the current precipitation well.

3. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 2 is characterized in that: The calculation method of the distance d between the next precipitation well and the current precipitation well is: Obtain various parameters during the construction process: permeability coefficient K, parallel connection spacing L, dewatering well diameter R, current underwater fill depth T; Substitute the various parameters obtained during the construction process into the formula in numerical form: Among them: d is the distance between the next precipitation well and the current precipitation well, the permeability coefficient K, the parallel connection distance L, the precipitation well diameter R, and the current underwater fill depth H.

4. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 1, characterized in that: The installation of the load-bearing beam also includes the following steps: Mark the positions of steel pipe piles on the load-bearing beams; Lift the load-bearing beams and ensure that the marks coincide with the steel pipe piles during the lifting process; Arc-shaped limiting steel plates are welded between the pile body and the load-bearing beam to fix the load-bearing beam.

5. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 1, characterized in that: The installation of the Bailey beam also includes the following steps: The Bailey beam is tested before entering the construction site, and after the test assembly is correct, it is assembled on site; Before installing the Bailey beam, measurement and layout are first performed on the load-bearing beam to determine the exact position of the Bailey frame; The Bailey beam is lifted by a crawler crane and placed at one end of the pond where the Bailey beam has been installed and in a straight line with the same; After aligning the pin hole of the lower chord of the Bailey beam and inserting the pin bolt, lift the rear end of the Bailey beam, insert the upper chord pin body and set the safety pin.

6. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 5, characterized in that: After the Bailey beam is accurately positioned, it is first firmly tied to the load-bearing crossbeam, then the limiter is welded, and then another set of Bailey beams is installed, and the two sets of Bailey sheet scissors struts are connected.

7. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 1, characterized in that: The bridge deck used for paving the bridge deck includes two specifications, one is a 16mm thick patterned steel plate, and the other is an assembled bridge deck with specifications of 6m×2m and 3m×2m, wherein: the assembled bridge deck adopts a 138mm thick customized steel panel, the transverse rib spacing is 750mm, the longitudinal rib spacing is 250mm, and the two ends are fixed to the secondary beam with screws. At the same time, 5*50 flat steel is welded at the joint. The bridge deck steel plate adopts a patterned anti-slip steel plate and is coated with a polymer anti-slip and anti-corrosion material. The anti-corrosion material adopts polyurethane oil-resistant, and the coating thickness is 1 to 2mm.

8. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 1, characterized in that: The steel trestle also includes a trestle abutment, and rubber pads are arranged at the abutment and the trestle plank.

9. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 3, characterized in that: The load-bearing crossbeam is composed of two I45a I-beams, and the Bailey beam adopts 321 type Bailey beam.

10. The method for combining double-row PLC pile cofferdam and steel trestle for over-deep ponds according to claim 1, characterized in that: The construction preparation process specifically includes the processing and storage of steel cofferdams, wherein the steel cofferdams include: steel pipe piles, steel sheet piles, tension steel bars, and an operating platform.

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