CN116497851A

CN116497851A - Detachable and maintained permanent-face structural cofferdam and anti-collision facility installation method

Info

Publication number: CN116497851A
Application number: CN202310513272.0A
Authority: CN
Inventors: 张东河; 倪波文; 张洋; 黄锋; 林阳; 桂凤阳; 陈迁; 陈意青; 吴青云; 覃江波; 李宏强
Original assignee: 2nd Engineering Co Ltd of MBEC
Current assignee: 2nd Engineering Co Ltd of MBEC
Priority date: 2023-05-09
Filing date: 2023-05-09
Publication date: 2023-07-28

Abstract

The invention belongs to the technical field of cofferdam anti-collision facilities, and provides a detachable and maintained permanent structure cofferdam and an anti-collision facility installation method, which comprises the following steps: s1, preparing work before assembling the cofferdam, S2, assembling and lowering the cofferdam; according to the invention, a permanent combining scheme is adopted through an anti-collision facility, namely, a steel sleeve box for constructing the bearing platform is reserved after the construction of the bearing platform is completed and is used as a permanent anti-collision facility, rubber parts are arranged on hanging legs and inner side plates at the upper part of the cofferdam, and a rubber fender is arranged at the outer side of the main pier sleeve box, so that a pier foundation can be protected, the sleeve box is prevented from directly colliding with the bearing platform, the impact energy is reduced, meanwhile, a large amount of additional temporary steel structure investment is reduced through permanent combining construction, the detachable structure is convenient for later maintenance, the replacement cost is reduced, the construction period is shortened, and the installation and maintenance safety risks are reduced.

Description

Detachable and maintained permanent-face structural cofferdam and anti-collision facility installation method

Technical Field

The invention belongs to the technical field of cofferdam anti-collision facilities, and particularly relates to a detachable and maintained permanent structure cofferdam and an anti-collision facility installation method.

Background

The cofferdam is a temporary enclosure structure constructed for constructing a permanent hydraulic facility in hydraulic engineering construction, a Niu Tianyang super-large bridge main pier bearing platform is constructed by adopting a permanent structure cofferdam, after pile foundation construction at a pier position is completed, a bridge deck system of a drilling platform in the bearing platform range is removed, and a high pile foundation steel casing is connected to serve as a steel casing hanging system; the main pier steel sleeve box cofferdam is assembled by using 150t crawler cranes or 100t gantry cranes at pier positions in blocks, and 350t jacks are put down to be in place for installation; the transition pier/auxiliary pier is assembled by using 150t crawler crane at the pier position in a block manner, a 150t jack is put down to be in place, after the cofferdam is installed in place, the gap between the cofferdam and the steel pile casing is filled after the axis deviation and the top surface elevation meet the requirements, a cofferdam bottom sealing construction platform and an underwater bottom sealing concrete pouring conduit are arranged, and cofferdam bottom sealing concrete is poured.

However, the above cofferdam facility still has the following problems when installed:

1. the sleeve box directly collides with the bearing platform to generate impact energy, so that the pier foundation is easy to damage, and the installation effect of the cofferdam is affected; 2. the temporary steel structure is put into a large amount, so that the cost of later maintenance is increased, the construction period is increased, and the risks of installation and maintenance are increased.

Therefore, there is a need to design a detachable and maintained permanent temporary structural cofferdam and an anti-collision facility installation method, which solve the problems existing in the prior art.

Disclosure of Invention

In order to solve the technical problems, the invention provides a detachable and maintained permanent temporary structural cofferdam and an anti-collision facility installation method, which are used for solving the problems that in the prior art, a pouring jacket directly collides with a bearing platform to generate collision energy, so that a pier foundation is easy to damage and the installation effect of the cofferdam is affected; meanwhile, a large amount of temporary steel structures are put into the process, so that the later maintenance cost is increased, the construction period is increased, and the problems of installation and maintenance risks and the like are increased.

A detachable and maintained permanent temporary structural cofferdam and an anti-collision facility installation method comprise the following steps:

s1, preparing work before cofferdam assembly

(1) Steel jacketed tank bottom plate open hole inspection

Before the cofferdam is installed, the situation of the hole opening of the bottom plate of the cofferdam is further checked according to the actual measurement data of the steel casing, the bottom plate needs to pass through the steel casing of the bored pile during the cofferdam installation, and whether the reserved hole formed on the bottom plate is accurate or not is the key for affecting the stable sinking and accurate positioning of the steel sleeve box, so that the coordinates, ovality, gradient and inclination direction of the steel casing are required to be accurately measured, and the hole is formed on the bottom plate of the steel sleeve box according to the measurement result; (2) Detecting the peripheral conditions of the steel casing, wherein the detection content comprises the outer wall of the steel casing and the underwater condition in the sinking range of the steel casing, the detection method of the outer wall of the steel casing adopts round steel to process a steel ring with the inner diameter 50mm larger than the diameter of the steel casing, the steel ring is sleeved into the steel casing, the steel casing is kept horizontally lowered, and whether the periphery of the steel casing has an obstacle influencing the sinking of the steel casing is checked; (3) Lofting of cofferdam installation position

According to the cofferdam mounting position, lofting is carried out on the central axis of the cofferdam, the axis of the important structure and the important sideline position, so that the accuracy of the cofferdam assembling and lowering positions is ensured.

S2, assembling and lowering the cofferdam, wherein in the step 1, the step I is as follows: after pile foundation construction is completed, pile inspection is qualified and grouting of a sounding pipe is completed, in order to ensure that the bottom of a steel sleeve box cofferdam is smoothly lowered to a position with a designed elevation of-7.5 m (the bottom of the cofferdam), measuring ropes are used for measuring the elevation of the sea bed before construction, part of a bored pile construction platform is dismantled, a long-arm excavator is arranged, the seabed or other obstacles affecting a deposition bed under the steel sleeve box cofferdam are cleaned in time, and the places where the excavator cannot excavate in place are cleaned by utilizing a grab bucket or an underwater dredging robot; and II: after the excavation of the cofferdam foundation pit is completed, measuring and checking the elevation of the seabed to meet the requirement of the lowering height of the cofferdam, and then connecting steel pile casings of No. 1, no. 4, no. 5, no. 9, no. 19, no. 20, no. 21, no. 22, no. 32, no. 37, no. 36 and No. 40 to the position of +10.5m, arranging brackets of a cofferdam assembly platform on the tops of the steel pile casings by using crawler cranes, and arranging a cofferdam assembly platform; step three: symmetrically hoisting cofferdam side plates (anti-collision boxes) by using two 150t crawler cranes or 100t gantry cranes according to the sequence of the middle part and the two ends, and finally closing the cofferdam side plates; step four: hoisting the bottom keels and the bottom plates to the brackets at the bottom of the steel bushing box according to the sequence from zone III to zone II to zone I by using two 150t crawler cranes or 100t gantry cranes, and welding the bottom plates of the bottom keels into a whole sequentially after the elevation, the plane position and the axis deviation of the bottom keels and the bottom plates are adjusted; step five: the bottom compartment is hung on the bottom panel in a segmented mode, and is placed at a designed position, then welded into a whole, welded with the bottom plate, then an inner support 2 (middle section) is installed, and finally the side plates, the cofferdam bottom compartment, the bottom panel and the keels are welded, so that the whole cofferdam system is formed into a whole; step six: installing a cofferdam on a high-connection steel pile casing, lowering a hanging distribution beam, arranging a 350t hydraulic jack at each lifting point (12 lifting points are arranged) on the lowering hanging distribution beam, installing a cofferdam guiding and limiting device on the inner side plate of the cofferdam corresponding to the steel pile casing (8 positions) at the corner position after the cofferdam is qualified, ensuring that a gap of 5cm is reserved between the joint surface of the cofferdam guiding and limiting device and the steel pile casing, filling the gap with hard rubber after the cofferdam guiding and limiting device is installed, binding the gap with the cofferdam guiding and limiting device by using iron wires, and simultaneously lifting and lowering all lifting points of the cofferdam: firstly, lifting the cofferdam integrally for 5cm, after checking that the conditions of the lifting points and all components are good, continuously lifting the cofferdam for 45cm, standing the cofferdam for 30 min, leveling the cofferdam, and dismantling a cofferdam mounting platform; step seven: after the cofferdam mounting platform is dismantled, each point synchronously and slowly descends to the position of the designed elevation of-7.5 m (the bottom end of the cofferdam), when the cofferdam mounting platform descends, elevation observation points can be set at proper lifting points or scribing can be carried out on a suspender according to 5-10 cm scales, so that the stress of each lifting point is uniform when the steel sleeve box descends, the descending is required to be uniformly commanded, each operator is required to concentrate on, the mutual coordination is proper, the operation steps are consistent, and the synchronous and slow whole descending is realized.

Preferably, in step (2) of S1, the underwater condition in the sinking range of the steel casing is mainly probed by a diver, in step (S2), after the depth of the pier-position central seabed excavation meets the requirement, the rest of the construction platform is required to be removed, in step (S2), the installation quality inspection of the water-stop adhesive tape is required to be enhanced when the cofferdam side plates are assembled, water leakage caused by breakage, breakage and dislocation is avoided, in step (S2), the hole size of the bottom plate at the pile position is determined based on the actual measured plane position and inclination of the pile foundation steel casing on site, so as to ensure that the bottom plate is not clamped with the steel casing in the lowering process, in step (S2), in order to keep stable in the cofferdam side plate (anti-collision box) assembly process, a temporary support structure is arranged, the temporary support is connected with the cofferdam side plates through screw holes, after the single side plates are installed, the lower end of the temporary support structure is welded with the bottom plate of the assembly platform, in step (S2), the scaffold operation platform is required to be installed before construction, and in step (S2), in the lowering process, each jack is controlled by a special person, and synchronous lowering is ensured.

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts the temporary steel structure construction platform for assembly, reduces the offshore hoisting risk, has high construction work efficiency, adopts the temporary steel structure construction platform for assembly, can improve the installation precision, improves the installation quality, detects the peripheral condition of the steel casing before the cofferdam is lowered, checks whether the steel casing still has an obstacle for preventing the steel casing from sinking into place, can smoothly lower and install the steel casing in place once, adopts intelligent mechanized installation, can save the investment of personnel, machinery and temporary measures to the greatest extent, reduces the construction period pressure caused by the traditional installation mode, adopts the whole lowering of the 350t hydraulic jack, ensures the whole synchronism of the lowering, improves the lowering efficiency and the installation progress, reduces the offshore operation frequency and avoids secondary pollution.

Drawings

FIG. 1 is a schematic illustration of an excavator construction in step one of the present invention;

FIG. 2 is a schematic view of a pile foundation according to the first embodiment of the present invention;

FIG. 3 is a schematic view of a step four weir plate (anti-collision box) of the present invention;

FIG. 4 is a schematic view of the welded bottom panel and keel of the cofferdam foundation of the present invention;

FIG. 5 is a schematic view of a step five temporary support structure of the present invention after welding with an assembly platform;

FIG. 6 is a schematic view of a step six drop hanger of the present invention;

FIG. 7 is a bottom closure hanger diagram of step seven of the present invention;

FIG. 8 is a schematic view of a main pier cofferdam crash box structure of the present invention;

FIG. 9 is a schematic view of a peripheral plugging device of a steel casing according to the present invention;

FIG. 10 is a schematic view of a first construction of a transitional pier/auxiliary pier cofferdam crash box in accordance with the present invention;

FIG. 11 is a schematic view of a second construction of a transitional pier/auxiliary pier cofferdam crash box in accordance with the present invention;

FIG. 12 is a schematic view of the arrangement of the main pier steel bushing box bottom keel of the present invention;

FIG. 13 is a schematic view of the transition pier/auxiliary pier steel bushing box bottom keel arrangement of the present invention;

FIG. 14 is a schematic view of the arrangement of the bottom compartment of the main pier steel bushing box of the present invention;

FIG. 15 is a schematic view of the internal support arrangement of the main pier steel sleeve cofferdam of the present invention;

FIG. 16 is a schematic view of the in-cofferdam support arrangement of the transition pier/auxiliary pier steel sleeve of the present invention;

FIG. 17 is a schematic diagram of the transverse bridge arrangement of the main pier steel box cofferdam lowering hanging system of the present invention;

FIG. 18 is a schematic view of the longitudinal bridge arrangement of the back cover hanging system of the main pier steel sleeve cofferdam of the present invention;

FIG. 19 is a schematic view of the longitudinal bridge arrangement of the transitional pier/auxiliary pier steel sleeve cofferdam suspension system of the present invention;

FIG. 20 is a schematic view of a cofferdam guiding and limiting device of the present invention;

FIG. 21 is a flowchart of the assembly and lowering of the steel box cofferdam with bottom in accordance with the present invention;

FIG. 22 is a schematic view of a main pier cofferdam floor and keel block of the present invention;

FIG. 23 is a schematic view of a transition pier/auxiliary pier cofferdam floor and keel block of the present invention;

fig. 24 is a flow chart of the anti-corrosion coating construction process of the present invention.

Detailed Description

Embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the invention but are not intended to limit the scope of the invention.

As shown in fig. 1 to 24:

examples: the invention provides a detachable and maintained permanent temporary structural cofferdam and an anti-collision facility installation method, which comprise the following steps:

S1, preparing work before cofferdam assembly

(1) Steel jacketed tank bottom plate open hole inspection

Before the cofferdam is installed, the situation of the hole opening of the bottom plate of the cofferdam is further checked according to the actual measurement data of the steel casing, the bottom plate needs to pass through the steel casing of the bored pile during the cofferdam installation, and whether the reserved hole formed on the bottom plate is accurate or not is the key for affecting the stable sinking and accurate positioning of the steel sleeve box, so that the coordinates, ovality, gradient and inclination direction of the steel casing are required to be accurately measured, and the hole is formed on the bottom plate of the steel sleeve box according to the measurement result; (2) The peripheral condition detection of the steel casing comprises the underwater condition of the outer wall of the steel casing and the sinking range of the steel casing. The method for detecting the outer wall of the steel casing adopts round steel to process a steel ring with the inner diameter 50mm larger than the diameter of the steel casing, the steel ring is sleeved into the steel casing, the steel casing is kept horizontally lowered, and whether barriers affecting the sinking of the steel casing box exist around the steel casing or not is checked. The underwater condition within the sinking range of the steel sleeve box is mainly explored by divers.

From the above, in order to ensure that the steel sleeve box can be smoothly lowered into place, the peripheral conditions of the periphery of the steel casing are detected to check whether an obstacle preventing the steel sleeve box from sinking into place exists.

(3) Lofting of cofferdam installation position

S2, cofferdam assembling and lowering steps (taking a main pier as an example, and other piers refer to the main pier)

(1) Step one: after pile foundation construction is completed, pile inspection is qualified, grouting of a sounding pipe is completed, in order to ensure that the bottom of the steel sleeve box cofferdam is smoothly lowered to the designed elevation of-7.5 m (the bottom of the cofferdam), measuring ropes are used for actually measuring the elevation of the seabed before construction, part of a bored pile construction platform is removed, a long-arm excavator is arranged, the seabed or other obstacles affecting a depositing bed under the steel sleeve box cofferdam should be cleaned in time, the places where the excavator cannot excavate in place are cleaned by a grab bucket or an underwater dredging robot, and after the excavation depth of the seabed at the center of a pier meets the requirements, the step two of the rest construction platform is removed: after the excavation of the cofferdam foundation pit is completed, measuring and checking the elevation of the seabed to meet the requirement of the lowering height of the cofferdam, and then connecting steel pile casings of No. 1, no. 4, no. 5, no. 9, no. 19, no. 20, no. 21, no. 22, no. 32, no. 37, no. 36 and No. 40 to the position of +10.5m, arranging brackets of a cofferdam assembly platform on the tops of the steel pile casings by using crawler cranes, and arranging the cofferdam assembly platform. Step three: and (3) symmetrically hoisting cofferdam side plates (anti-collision boxes) by using two 150t crawler cranes or 100t gantry cranes according to the sequence of the middle part and the two ends, and finally closing the cofferdam side plates. When the cofferdam side plates are assembled, the installation quality inspection of the water stop adhesive tape is required to be enhanced, and water leakage caused by breakage, breakage and dislocation is avoided. Step four: and (3) hoisting the bottom keels and the bottom plates to the bracket at the bottom of the steel bushing box according to the sequence from zone III to zone II to zone I by using two 150t crawler cranes or 100t gantry cranes, and welding the bottom plates of the bottom keels into a whole sequentially after adjusting elevation, plane position and axis deviation of the bottom keels and the bottom plates. The size of the hole of the bottom panel at the pile position is determined according to the actual measured plane position and the inclination of the pile foundation steel casing on site, so that the bottom panel is ensured not to clamp the steel casing in the process of lowering; step five: the bottom compartment is hung on the bottom panel in a segmented manner, the bottom compartment is welded into a whole after being placed at a designed position, the bottom compartment is welded with the bottom panel, then an inner support 2 (middle section) is installed, and finally the side plates, the cofferdam bottom compartment, the bottom panel and the keels are welded, so that the whole cofferdam system is formed into a whole; in the assembly process of the cofferdam side plates (anti-collision boxes), a temporary supporting structure is arranged for stability, the temporary support is connected with the cofferdam side plates through screw holes, and after the single side plates are installed, the lower ends of the temporary supporting structure are welded with the bottom plate of the assembly platform. Step six: a cofferdam lowering hanging distribution beam is arranged on a steel pile casing which is connected with the cofferdam, a 350t hydraulic jack is arranged at each hanging point (12 hanging points are arranged) on the lowering hanging distribution beam, after the cofferdam is qualified through experience, a cofferdam guiding and limiting device is arranged on the inner side plate of the cofferdam corresponding to the steel pile casing (8 positions in total) at the corner position, a gap of 5cm is reserved between the joint surface of the cofferdam guiding and limiting device and the steel pile casing, after the cofferdam guiding and limiting device is installed, the gap is filled with hard rubber, and the cofferdam guiding and limiting device is tightly bound with the cofferdam guiding and limiting device through iron wires. All lifting points lift and lower the cofferdam simultaneously: firstly, lifting the cofferdam integrally for 5cm, after checking that the conditions of the lifting points and all components are good, continuously lifting the cofferdam for 45cm, standing the cofferdam for 30 min, leveling the cofferdam, and dismantling a cofferdam mounting platform; step seven: after the cofferdam installation platform is dismantled, each point synchronously and slowly descends to the position of the designed elevation of-7.5 m (the bottom end of the cofferdam), and each jack is controlled by a special person in the descending process, so that synchronous descending is ensured, and a scaffold operation platform is required to be installed before construction. When the steel sleeve box is put down, elevation observation points can be set at proper lifting points or scribing can be carried out on the suspenders according to 5-10 cm scales, so that the steel sleeve box is ensured to be uniformly stressed when being put down, the steel sleeve box is required to be uniformly commanded to be put down, operators are required to concentrate on each other, the operation steps are properly matched, and the synchronous and slow overall lowering is achieved. The elevation of the side plate of the box needs to be observed every 1m of the box is put down. When the lowering is required, the unsynchronized deviation value of each lifting point is controlled within 1cm, if the unsynchronized deviation value is observed, the lowering should be stopped immediately, and after the plane and the elevation of the observation point are checked and the local lowering points are adjusted to be consistent, the lowering can be performed again. After the steel sleeve box is lowered in place, a measurer retests the axial plane position of the elevation bearing platform of each observation lifting point and the verticality of the steel sleeve box, and after the position and the elevation are adjusted, the sleeve box is fixed. When the cofferdam is lowered to the top of the cofferdam below the hanging distribution beam, an inner support 1 (arc sections at two ends) is installed, after the cofferdam is continuously lowered to the designed elevation, the top end of the cofferdam is measured and corrected in time, a cofferdam back cover hanger is installed, in order to reduce deformation of a bottom plate of the cofferdam in the construction process of back cover concrete, a 50t jack is adopted to pre-pull a boom, the pre-pull force is 100kN, the pre-pull is in place, the boom is anchored in place, a back cover concrete construction platform is arranged, and the construction of the cofferdam back cover concrete is carried out: the periphery of the steel pile casing is plugged, and as gaps exist between the cofferdam and the steel pile casing, in order to prevent the loss of underwater concrete during bottom sealing, the gaps between the steel pile casing and a cofferdam bottom plate are plugged in advance, and the plugging method is as follows: before the cofferdam is put into water, a cofferdam plugging annular plate (10 mm thick, 100mm wide steel plates, each steel casing peripheral annular plate is divided into 4 blocks, the inner diameter of the steel casing is 60mm larger than the outer diameter of the steel casing) manufactured in advance is sleeved into the steel casing, then angle steel 110 multiplied by 70 multiplied by 6mm is welded on a cofferdam bottom panel to limit, after the cofferdam is put into place, when a diver cleans the periphery of the casing, the gap between the annular plate and the casing is adjusted, the annular plate and the casing are closely attached as much as possible, and then the annular plate is temporarily fixed, so that the plugging purpose is achieved, and the plugging device is shown in figure 9; according to the size, the weight and the condition of construction machinery equipment of the cofferdam structure, the main pier steel sleeve box cofferdam is assembled at a pier position, construction is carried out by utilizing the scheme of integrally lowering a jack, and the integral assembly and lowering flow of the cofferdam is shown in a figure 20. The steel sleeve cofferdam consists of side plates (anti-collision boxes), bottom keels, bottom panels, bottom compartments, inner supports, hanging systems and the like, wherein Q235B steel is adopted as a main material, and the statistics of the number of single steel sleeve cofferdam materials are shown in the following table:

(1) Cofferdam side plate (crash box): the 22# and 23# main pier cofferdam side plates, namely the anti-collision box, adopt double-wall structures, the side plates simultaneously serve as bearing platform templates, the plane outline size is 79m (transverse bridge direction) multiplied by 35.4m (forward bridge direction), the height is 10.8m, the wall thickness is 2-3 m, and the top elevation of the anti-collision box is +3.3m. For construction and simple to operate, the crashproof case is divided into A, B, C, D, E, F, G seven model sections, and each model has 4 sections, totally 28 sections, and the junction surface adopts high strength stainless steel bolted connection between the section, and the heaviest section is the G section, and the outline is long 7.804m, and is about 48.677t. The main materials of the side plates are steel plates with the thickness of 10mm, 12mm and 26mm and angle steel with the thickness of 140 multiplied by 90 multiplied by 10 mm; the main pier cofferdam crash box structure is shown in figure 8. The side plates of the 20# transition pier, the 25# transition pier and the 21# auxiliary pier cofferdam, namely the anti-collision box, adopt double-wall structures, the side plates simultaneously serve as bearing platform templates, the plane outline dimension is 33.8m (transverse bridge direction) multiplied by 16.6m (forward bridge direction), the height is 6.8m, the wall thickness is 2.5m, and the top elevation of the anti-collision box is +3.3m. For construction and simple to operate, the crashproof case divide into A, B two types section, and each model has 4 sections, totally 8 sections, adopts high strength stainless steel bolted connection to connect the face between the section, and the heaviest, longest section be the B section, and the outline is long 11.144m, heavy about 37.984t. The main materials of the side plates are steel plates with the thickness of 12mm, 10mm and 26mm and angle steel with the thickness of 140 multiplied by 90 multiplied by 10 mm; the transitional pier/auxiliary pier cofferdam crash box structure is shown in fig. 10 and 11. (2) bottom joist and bottom panel: the bottom plate of the steel sleeve box adopts a bottom die structure formed by welding bottom keels and bottom plates, the main keels of the steel sleeve box bottom of the main pier are HM390 multiplied by 300 steel bars, the secondary keels are I32a I-steel bars, the transition pier/auxiliary pier steel sleeve box bottom keels are HM390 multiplied by 300 steel bars, the steel sleeve box bottom plates are all 6mm thick steel plates, the stiffening ribs are angle 75 multiplied by 50 multiplied by 6 steel bars, and the bottom plates are provided with holes at the steel pile casing; the arrangement of the main pier steel sleeve box bottom keels is shown in fig. 12, and the arrangement of the transition pier/auxiliary pier steel sleeve box bottom keels is shown in fig. 13. (3) bottom compartment: three rows of bottom compartments are arranged above the main pier steel sleeve box weir bottom panel, the bottom compartments are a truss structure consisting of I25a, I22a, [16 ] and +.75X50X6 steel, the width is 3.19m, the height is 2.3m, the wall plates are 6mm thick steel plates, and the stiffening ribs are +.75X50X6 steel; the arrangement of the compartment at the bottom of the main pier steel bushing box is shown as 14. (4) internal support: the main pier, the transition pier and the auxiliary pier steel sleeve box are all provided with an inner support at the top opening position. The single inner support of the main pier steel sleeve cofferdam adopts 4 steel pipes with phi 426 multiplied by 6mm as main pipes, the steel pipes with phi 273 multiplied by 6mm are used as lattice members formed by connecting pipes, the central elevation of an upper pipe orifice is +0.920m, the central elevation of a lower pipe orifice is-0.580 m, and 3 inner supports are arranged in the whole cofferdam; the inner support of the transition pier/auxiliary pier steel sleeve box cofferdam adopts phi 426 multiplied by 6mm steel pipes, the elevation of the pipe orifice center is +1.900m, and the inner support of the whole cofferdam is 4; the internal support arrangement of the main pier steel sleeve cofferdam is shown in fig. 15, and the internal support arrangement of the transition pier/auxiliary pier steel sleeve cofferdam is shown in fig. 16. (5) a hanging system: the hanging system consists of longitudinal beams, cross beams, hanging rods and steel pile casings, is used for bearing the weight of the cofferdam dead weight and the weight of the back cover concrete, and is divided into a lower hanging part and a back cover hanging part, wherein the lower hanging part of a main pier is arranged on the top of the high-receiving steel pile casings, and a lower hanging part distribution beam consists of welded box beams with the cross section dimension of 1400 (height and width) x 30 (thickness of a single-channel web, total 2 channels) x 24 (thickness of a top plate) mm, and is welded on a special support (a reinforcing structure) at the top opening of the pile casings along the longitudinal bridge direction, and jacks are arranged at the positions of hanging points at two ends of the distribution beam; the arrangement of a main pier steel sleeve cofferdam lowering hanging system is shown in fig. 17, a transition pier and an auxiliary pier cofferdam lowering hanging is arranged on the top of a high-steel pile casing, a lowering hanging distribution beam consists of welded box beams with the cross section dimension of 1400 (height and width) multiplied by 30 (thickness of a single-channel web, 2 channels in total) multiplied by 24 (thickness of a top plate), 2 layers are arranged in total, a bottom distribution beam is welded on a special support (bracket) at the top opening of the pile casing along the transverse bridge direction, a top distribution beam is arranged on the bottom distribution beam along the longitudinal bridge direction, jacks are arranged at the positions of hanging points at two ends of the top distribution beam, a main pier cofferdam lowering hanging boom adopts phi 15.2mm steel strands, a transition pier and an auxiliary pier lowering hanging boom adopt phi 32mm threaded steel bars, and the main pier, auxiliary pier and the cofferdam sealing hanging are formed by utilizing the jacks: two 2I32a and 2I45a double-spliced I-steel distribution beams are arranged on each special support (reinforcing structure) welded on the top opening of the pile casing as supporting points of longitudinal beams, each longitudinal beam consists of 6 rows of Bailey beams and welding box beams with the cross section size of 1400 multiplied by 30 multiplied by 24mm (the welding box beams are the same as or shared by the hanging distribution beams), bailey beam limiting devices are arranged at the supporting points, the hanging distribution beams are arranged on the longitudinal beams along the transverse bridge direction, the hanging distribution beams consist of double-spliced I-steel with 2I22a and 2I45a, hanging points are arranged at two ends of the hanging distribution beams, and a cofferdam back-cover hanging suspender adopts phi 32mm finish-rolled screw-thread steel bars; the main pier steel sleeve cofferdam back cover hanging system is shown in fig. 18, and the transition pier/auxiliary pier steel sleeve cofferdam hanging system is shown in fig. 19. (6) guiding and limiting device for steel sleeve cofferdam: the steel sleeve box can drift downstream under the action of the hydraulic pressure of the flowing water after sinking into water, dynamic loads such as the hydraulic pressure of the flowing water, the wave force and the like or the asynchronization of the descending heights of all lifting points in the cofferdam descending process, the freely suspended steel sleeve box is flexible, and a cofferdam descending guide limiting device is arranged on the steel sleeve box cofferdam. The guide limiting device consists of a guide plate, a steel pipe with the diameter of 820 multiplied by 10mm and a stiffening plate, wherein the guide plate and the stiffening plate are steel plates with the thickness of 10mm, the guide plate is made into an arc with the radius of 50mm larger than that of the steel casing, one end of the guide limiting device is welded at the corner or the arc part of the steel sleeve box, 2 guide limiting devices are arranged at each position in order to keep the top opening and the bottom opening of the cofferdam on the same plumb line, and a certain gap is reserved between the end part of the guide plate and the outer wall of the steel casing. The steel sleeve box bottom opening positioning is to control the plane position of the steel sleeve box to be lowered by using a steel casing hole at the steel sleeve box bottom plate as a positioning hole and matching with a guiding limiting device to limit the moving direction during lowering; the cofferdam guiding and limiting device is shown in fig. 20, the lower ends of the hanging rods of the lowering hanging and the back cover hanging are respectively fixed on the hanging rod bases of the anti-collision box and the bottom plate, and the upper ends of the hanging rods are fixed on the distribution beam or the hanging distribution beam.

1. Preparation for construction

(1) Material purchase: in order to ensure the quality of the material and the smooth development of the material from purchasing to checking and accepting work, the purchasing and accepting of the material must be implemented according to the following procedures. (1) All materials adopt products with credit guarantee factories; (2) a technical responsible person or technician compiles a material demand list on the premise of proper loss according to the construction drawing requirements and the reasonable blanking principle; (3) the material staff makes a purchasing plan and reports the approval of the operation team leader according to the material demand list, and the project manager approves the large quantity and important materials; (4) the material staff makes a purchasing plan and simultaneously carries out comprehensive evaluation on the material suppliers by departments such as technical quality and the like, and mainly evaluates comprehensive factors such as the supply time rate, quality condition, price and the like; (5) and determining that the material design purchasing work can be performed behind the qualified suppliers. (2) material inspection: (1) when steel enters the field, manufacturers must provide delivery receipts, material certificates and qualification certificates, and the names, specifications, models and other marks of the materials are clear; (2) the geometric dimension of the steel sheet meets the requirements of the general requirements of the surface quality of hot-rolled steel sheets (GB-T14977-2008) and the related technical regulations of hot-rolled steel sheets (GB/T706-2008) by visual inspection and measuring tools; (3) the production standard of a checking manufacturer before the welding material enters the field is met, and the product quality of the welding material meets the related technical regulations of non-alloy steel and fine grain steel welding rods (GB/T5117-2012), steel wires for fusion welding (GB/T14957-1994), steel wires for gas shielded welding (GB/T14958-1994) and solid welding wires for non-alloy steel and fine grain steel for submerged arc welding, flux-cored wires and welding wire-flux combination classification requirements (GB/T5293-2018); (4) other materials related to the project are inspected through full inspection, and quality certification documents of products are inspected, so that varieties, specifications, performances and the like of the materials are ensured to meet national product standards and design requirements; (5) the materials which are checked to be qualified are classified and stacked and stored according to specifications, models, grades, names and the like, and are marked, wherein the marks comprise names, specifications, quantity, material sources, production plants, commodity names, production and commodity date, purposes and inspection states, and all materials are stored and distributed by special persons. (3) Construction technology management (1) technicians carefully study and understand anti-collision box technical files (data such as design drawings, specifications, technical requirements and the like), and communicate with related units and departments in time when encountering problems; (2) the technical responsible person organizes related personnel to carry out technical engagement, and proposes possible problems in the manufacturing process and a method for solving the problems; (3) and (5) making relevant quality and safety standards. 2. Manufacturing a side plate of the anti-collision box: and considering site construction conditions, and according to the requirements of design files, dividing the side plates of the anti-collision box into blocks according to design drawings. Each crashproof case curb plate divide into wallboard, platform board, primary and secondary frame, annular slab, connecting plate, piece single element such as stiffening plate, crashproof case curb plate processing place is responsible for producing each crashproof case curb plate unit piece, then utilizes crawler crane or portal crane to splice the unit piece in advance into whole. (1) manufacturing a jig frame: the anticollision case is huge, in order to ensure anticollision case manufacturing accuracy, should set up the bed-jig according to structural feature, the quality requirement that the bed-jig set up is: it must have sufficient rigidity to meet the requirements of the manufacture of the unit block of the crash box and not to deform when the operator works thereon. (1) The surface unevenness of the plane jig frame should be less than 2mm; (2) the diagonal error of the jig frame plane die is not more than +/-5 mm; the error of the profiling in the vertical direction to the foot line is not more than +/-3 mm; (3) the jig frame is provided with a panel positioning device, and meanwhile, the jig frame is also provided with a certain capacity of restraining welding deformation, a restraining locking device is needed, the reverse deformation is reserved, and measurement observation points are needed to be arranged on the periphery of the jig frame so as to ensure that the single chip is accurate in geometric dimension; (4) after the jig frame is manufactured, the jig frame must be fully checked to ensure the use requirement; (5) the precision and the stress of different jig frames are consistent, so that the consistent sizes of products welded by the different jig frames are ensured. (2) lofting: in the manufacturing process of the anti-collision box, the special-shaped workpieces, including horizontal ribs, compartment plates, node plates, angle steel cut limbs and other parts with complex shapes in assembly and positioning, are subjected to lofting, the sizes of the parts are ensured to be accurate, and qualified assemblies are assembled. (1) The lofting work must be done by technically better cold workers; (2) the lofting staff is very familiar with the lofted drawings and is familiar with the application and technical specification requirements; (3) all measuring tools and reference tools used for lofting can be used only after being qualified by national metering device verification departments, so that the lofting precision is ensured, and the manufacturing requirements are met. The steel structure lofting tolerance is given in the following table:

Sequence number	Project	Tolerance (mm)
			1	Width and length of	+1.0，-1.0
2	Offset of any point on the curve template	1.0

(3) Sizing and blanking

(1) Before blanking, the model and specification of the steel must be known, and the appearance quality of the raw materials is checked; (2) the machining allowance is reserved when a machining line is drawn, so that the geometric dimension of the part is ensured; (3) various processing lines are required to be drawn according to the standard, and marks are punched on the processing lines, the bending lines, the central lines, the alignment lines, the compartment plate position positioning lines and other application samples, and meanwhile, the marks and the component numbers are marked by paint; (4) the blanking must be reasonably arranged and sleeved, so that the material utilization rate is fully improved. Care should also be taken not to create cross welds during trepanning. Meanwhile, repeated welding seams are not required to be generated, so that superposition of welding stress is easy to generate, and the stress of the structure is not facilitated. The method comprises the steps of (1) carrying out square finding on a blanking steel plate for a larger rectangular member, and blanking after square finding; (5) the shrinkage allowance of the plates and the shrinkage weld allowance of the node weld seams are considered during blanking, so that the assembly allowance is considered; (6) the defect of the pit collapse generated in the surface processing of the steel plate is repaired, and the repair is in accordance with the following regulations:

when the depth of pits or flaws on the local surface of the steel is more than 1mm, grinding and smoothing the steel; when the depth exceeds 1mm, the steel is subjected to repair welding and then is ground and smoothed; when the depth of lamellar cracks on the local edge of the steel is not more than 10mm, repair welding and grinding repair can be carried out after the cracks are removed; when the depth of the notch or the pit at the gas cutting edge is smaller than 2mm, the gas cutting edge can be ground and smoothed, and when the depth exceeds 2mm, the groove is ground and repaired after the groove is ground and repaired; for edge cracks generated during bending processing, the edge cracks should be treated according to the above-mentioned regulations after the reason is ascertained; (7) the shearing is only suitable for secondary parts or parts to be reprocessed after shearing, and the sheared edges are tidy and have no defects of burrs, reverse openings, meat deficiency and the like. The allowable deviation of the shearing dimension is +/-2 mm, and the edge lack is not more than 1mm; (8) parts whose rear edges are not machined after precision (semi-automatic) cutting, are to meet the following table specifications:

Cutting edge surface quality requirements

(4) Correction, edge processing and classification stacking: (1) for parts and components that deform due to shear or natural distortion, correction is necessary; (2) for parts and components which are deformed in two dimensions due to hot working and welding, mechanical correction or flame correction is adopted; (3) for corrected parts or components, the steel structure engineering construction quality acceptance criterion (GB 50205-2001) is required to be met; (4) for parts to be edge machined, the following table specifications should be met.

Edge processing tolerance (mm)

Sequence number	Project	Tolerance of
			1	Part width and length	±1.0
2	Straightness of processed edge	I/3000, and should not be greater than 2.0
			3	Included angle between two adjacent sides	±6′
4	Perpendicularity of the processed surface	0.025t, and should not be greater than 0.5

(5) The corrected and corrected parts and components are inspected to be qualified, and then are classified and stacked according to the number of the corrected and corrected parts and components and marked. (4) preparation of wallboard: (1) the inner side wall plate and the outer side wall plate of the side plate of the anti-collision box are different in size, and the jig frame is adjusted according to the size during manufacturing; (2) according to the area feeding condition, the panel is assembled into a whole. Every two steel plates are processed, after square finding, a main and secondary frame, a horizontal annular plate and a positioning line of a platform plate (an outline line of a panel is firstly popped up), and then a sample punch is used for punching the positioning line to make marks. Every 500mm interval is required, three points are made, and every point is 30mm interval; (3) the butt joint of the panels adopts double-sided grooves, and the welding is carried out according to a welding process; (4) welding shrinkage allowance is reserved when the panels are assembled, and the welding allowance of each steel plate is about 1.5L/1000; (5) the correction deformation of the panel can be adjusted by flame.

(5) Preparing a ring plate and a platform plate: (1) because the widths of the side plate annular plates and the platform plates are different, after the annular plates and the platform plates of one specification are manufactured, the jig frame is readjusted, and after the inspection is qualified, the other specification can be assembled; (2) to facilitate the installation of the compartment plate, the platform plate is broken at the compartment plate, so that the ring plate is segmented differently according to the different plates. The determination principle of the breaking position is that the sections of the horizontal annular plates are not on the same section; (3) the ring plate and the platform plate are subjected to sectional blanking according to the drawing size, and a numerical control cutting machine is used for perforating the platform plate; (4) butt-jointing on the jig frame, and welding according to a welding process, wherein the principle is that welding is performed symmetrically on the two sides after the middle; (5) the steel plates are butted with equal strength and welded according to a welding process; (6) the welding correction adopts a mechanical method and a flame method. (6) manufacturing a primary and secondary frame: (1) the wall thickness of the outer side plate of the anti-collision box is different, and the main and secondary frames are different in size. The secondary frame mainly comprises angle steel, and the main frame can be divided into a panel, a stiffening plate and the like; (2) the preparation of the main and secondary frames is the same as that of the annular plate and the platform plate; (3) separately preparing a stiffening plate of the main frame, and blanking by using a numerical control cutting machine according to a blanking process; (4) the welding requirements are the same as for the panels. (7) preparation of a separator: (1) the partition board is used for reinforcing the panel and consists of stiffening rib angle steel and a panel; (2) firstly, the partition board panels are assembled, and the plates can be transversely spliced and vertically spliced according to the material condition. The panel is firmly spot-welded and then ejected out of the outer contour line of the panel and the positioning line of the vertical stiffening rib; (3) the vertical angle steel is arranged on the panel according to the positioning line and is firmly spot-welded; (4) the panel is butted by equal strength, and is beveled to be welded according to a welding process; (5) when the partition plates are welded, the stiffening rib angle steel is welded firstly, the panel is transversely spliced, the stiffening rib angle steel is welded from the middle to the two sides and from the center to the periphery, intermittent welding is carried out according to a welding process, and the length and the interval of welding seams are 75mm. Then welding transverse butt welding seams, and welding each seam from the middle to two sides according to the welding process requirement; (6) the vertically spliced panels are adopted, long and straight welding seams of the panels are welded firstly, and the panels are symmetrically welded from the middle to the two sides according to the welding process requirement, so that the welding deformation is reduced; (7) the angle steel is welded after the panel is welded, and the method is the same as the welding of the panel angle steel; (8) flame straightening deformation can be adopted after welding. (8) preparation of a connecting plate: the connecting plate is positioned at the joint of the two side plates and is connected with the two side plates through bolts. (1) The panel of the connecting plate is assembled, and the plate can be transversely spliced and vertically spliced according to the material condition. The panel is firmly spot-welded and then the outer contour line of the panel is popped up; (2) the panel is butted by equal strength, and is beveled to be welded according to a welding process; (3) the long straight welding seams of the panel are symmetrically welded from the middle to the two sides according to the welding process requirement, so that the welding deformation is reduced; (4) flame correction deformation can be adopted after welding; (5) finally, checking the outer contour line of the panel and cutting; (6) due to the irreplaceability of the side plate specifications, the connection plates can be trepanning in groups of two. (9) unit cell assembly: before assembling the unit blocks, the assembly jig should be checked, and the next process can be performed after confirming that the assembly jig is error free. The assembly sequence of the single elements is as follows: (1) first, the bottom wall panel is assembled. The panel plates of the wall plates are sequentially arranged on the assembly jig frame according to the number, the assembly jig frame is assembled into a whole, the outer side contour lines, the horizontal annular plates of each layer and the positioning lines of the platform plates are on the same straight line, the panel plates are firmly spot-welded after the inspection is qualified, and the dislocation between the two adjacent plates is smaller than 2mm. And installing the ring plates and the platform plates, wherein the ring plates and the platform plates of each layer are sequentially installed on the panel according to the number by taking a horizontal positioning line as a standard during installation. Each layer of annular plate and the platform plate are perpendicular to the panel, and each two layers of spacing errors are firmly spot-welded after being inspected to be qualified by 2 mm; (2) and installing a primary and secondary frame. And sequentially installing the main and secondary frames on the panel according to the positioning lines of the main and secondary frames on the side panel. The main and secondary frames are vertical to the panel, and the interval error of every two frames is firmly spot-welded after 2mm of inspection is qualified; (3) and installing a partition board. Inserting the partition board according to the partition board positioning line on the panel; (4) the horizontal support is mutually perpendicular to the panel horizontal support; (5) and the upper side plate panel is installed, the same as the outer side plate panel in installation, and the main and secondary frames, the annular plates, the platform plates and the partition plate positioning lines of the panels are ensured to be relatively overlapped with all the installed bottom plate panels in assembly. When the clear distance of the panel of the wallboard is smaller than +/-4 mm, the clear distance, the size of the outer frame of the panel and the upper and lower positioning lines are overlapped, and spot welding is firm after inspection; (6) and (5) installing a connecting plate. When the connecting plates are installed, the connecting plates are fixed on the jig frame through bolts, the other corresponding connecting plates are guaranteed to be on the same plane, the sections of the butt joint positions of the two side plates are guaranteed to be the same, and the same bolt hole positions are free of deviation, so that final assembly of the anti-collision box is guaranteed; (7) welding: when the anti-collision box unit blocks are welded, the ring plate and the platform plate are welded firstly, then the connection welding seam of the main and secondary frames and the partition plate is welded, then the connection welding seam of the panel stiffening plate is welded, and finally the panel butt welding seam is welded. And after all welding lines are completed, welding the connecting plate after the dimension inspection of the side plate is correct. All welding seams are welded according to the welding process requirements, and the welding seams are flat welding, flat fillet welding and vertical welding. After one surface of the part which is not welded is welded, turning over the steel shell, and then welding the steel shell, wherein the method is the same as the sequence; (8) all assembled spot welding must be firm and reliable, and the length of a single spot welding seam must be greater than 10mm. Before assembly, the weld joint area, rust, greasy dirt, oxide skin and the like should be removed. After assembly, the deviation of each segment should be checked, and the following table should be met.

Tolerance of each section of the crash box

Sequence number	Project	Tolerance (mm)
			1	Ring plate, platform plate, primary and secondary frame spacing	±2
2	Width and length of	±3
			3	Inner and outer wall spacing	+4，0
4	Diagonal difference	4
			5	Surface irregularities	3

(9) The vertical butt welding seams of the anti-collision box panels are staggered, and the horizontal heights are controlled to be 1.0-1.5 m staggered; the pitch is preferably not less than 1.0 m. The horizontal rib connecting welding seams between the single elements of the anti-collision box should also be arranged in a staggered way, and the welding seam spacing is preferably not less than 1.0 m. The temporary connection code plates are reduced as much as possible in the manufacture of the component, when the code plates are welded, undercut and arc pits on a base material are avoided, the base material is not damaged when the clamp or the code plates are assembled and disassembled, the code plates are cut off and hammered in an inaccurate mode, and the base material is ground down by a grinder after the position 1-3 mm away from the surface of the base material is cut by oxygen (the base material is not damaged). (10) welding: (1) preliminary determination of CO ₂ Welding is carried out by gas shielded welding and manual arc welding, welding parameters are shown in the following table, and correction is carried out according to welding process evaluation.

CO ₂ Gas shielded welding process parameter meter

Manual arc welding process parameters I _{Welding process} ＝(30～50)D _{Welding rod} To be selected and correspondingly adjusted according to different welding positions. (2) Before welding, the iron rust, scale, greasy dirt, and other impurities in the to-be-welded area must be thoroughly cleaned, the slag and splashes must be cleaned after welding, and the welding seam which is required to be polished by a drawing must be polished smoothly; (3) by CO ₂ The gas shielded welding meets the windproof and rainproof conditions, and CO ₂ The purity of the gas is more than 99.5%; (4) the length of the positioning welding seam is 50-100 mm and the welding leg of the positioning welding seam is smaller than 1/2 of the design welding leg. Tack welding does not allow defects to exist; (5) the distance between the splicing weld joint of the plate and the structural weld joint is larger than 100mm; adopting welded and lengthened plates, wherein the length of the welded and lengthened plates is not smaller than 1000mm, and the width of the welded and lengthened plates is not smaller than 200mm; the interval between the T-shaped joint cross welds is not less than 200mm; (6) drawing prescribes that welding of welding seams of the components subjected to penetration welding is not suitable for overhead welding; (7) during welding, 300mm of each end of the fillet weld between the horizontal rib plate and the panel is left to be unwelded, and the two ends are left to be adjusted in the next procedure if horizontal ring staggered joint existsThe connecting part of the horizontal ring can be changed into an insert, and the insert length is more than 600 mm. And (11) hole making: the bolt holes are drilled, punching or hole burning is forbidden, and the requirements on machining precision and hole pitch are as follows:

bolt hole tolerance meter

Sequence number	Project	Tolerance of
			1	Diameter (mm)	+1.0，0.0
2	Roundness (mm)	2.0
			3	Straightness (mm)	0.03t, and should not be greater than 2.0

Tolerance of bolt hole pitch

Bolt hole pitch range (mm)	≤500	501～1200	1201～3000	＞3000
					Spacing (mm) between any two holes in the same group	±1.0	±1.5	-	-
End hole spacing (mm) between two adjacent groups	±1.5	±2.0	±2.5	±3.0

3. Bottom keel, bottom panel, bottom compartment, inner support and hanging system manufacture

The girth and bottom boards are manufactured by small blocks so as to be convenient for transportation to a construction platform, and the manufactured small blocks are assembled into 5 large blocks, wherein the size of the area I with the largest weight is 14.25 multiplied by 31.4m, the weight is about 51.4t, the sizes of the remaining areas II and III are 11.5 multiplied by 31.4m, 11.5 multiplied by 19.8m, and the weights are about 46.5t and 34.7t respectively. The transition pier/auxiliary pier cofferdam bottom keel and bottom panel are assembled into 2 large blocks, wherein the size of the area II with the largest weight is 16.5 multiplied by 11.6m, the weight is about 30t, the size of the remaining area II is 11.5 multiplied by 31.4m, and the weight is about 19.1t. The bottom keel and the bottom panel of the boundary area can be assembled with a main block on one side to form a whole, or scattered components of the bottom keel and the bottom panel can be assembled at the end after the main block is assembled to a preset position; main pier cofferdam floor and keel block are shown in opinion fig. 22 and transition pier/auxiliary pier cofferdam floor and keel block are shown in opinion fig. 23. The hanging system is manufactured according to each component, and when the ground transportation is carried out, the support in the bottom compartment is carried out in a sectional manufacturing mode. The inner support 1 and the bottom compartment 1 (arc sections at two ends) are divided into 3 sections, each section is 10.467m long, the weight of each section of the inner support is about 3.53t, and the weight of each section of the bottom compartment is about 10.4t; the inner support 2 and the bottom compartment 2 (middle rectangular section) are divided into 2 sections, each section is 9.9m long, the weight of each section of the inner support is about 3.558t, and the weight of each section of the bottom compartment is about 8.7t. Joints manufactured in sections should be staggered; ensuring the accuracy of the manufacturing precision of each component and the structure of each connecting surface so as to ensure that the on-site installation can be smoothly carried out. When the components are welded and lengthened, butt welding seams are properly staggered, and the welding seams are carried out according to the welding height and the welding length required by design, so that good quality is ensured. When the welding processing component is manufactured, strict measures are formulated to reduce the processing deformation of the component, reduce the residual stress of the welding seam and correct the deformation in time.

4. Weld detection

And after the welding is finished, all welding seams are inspected in a full-scale mode, whether welding gaps exist in the welding seams, welding flash, unfused welding and the like are inspected, inspection standards are shown in the table, the welding seams and geometric dimension inspection are immediately modified after being unqualified, and the positioning and the restraint of the welding seams are relieved after the welding seams and the geometric dimension inspection are totally qualified.

Appearance quality standard of secondary and tertiary welding seams

Butt weld and full penetration combination weld dimension tolerance

Partial penetration combination weld and fillet weld overall dimension tolerance

Note that: (1) h is a _f The local fillet size of the called weld seam with the diameter of more than 8.0mm is allowed to be 1.0mm lower than the design requirement value, but the total length is not required to exceed 10% of the length of the weld seam; (2) and welding the two ends of the welding seam of the H-shaped beam web plate and the flange plate within the range of twice the width of the flange plate, wherein the welding leg size of the welding seam is not lower than the design value.

5. And (3) water tightness test of the steel sleeve box: after each section of the steel jacket is manufactured, a kerosene penetration test should be performed on the weld. The lime water is brushed on the two sides of the welding line by using a brush, kerosene is brushed on the welding line on the inner side of the sleeve after the lime water is dried, and after 30-60 min, whether kerosene permeation marks exist on the outer side of the sleeve is checked, repair welding is carried out on unqualified positions through test inspection, and repeated inspection is needed after repair welding. After the steel sleeve box wallboard is assembled into a whole on site, the same requirement on the on-site assembled welding seam is met for kerosene penetration test, and the overall watertight performance of the sleeve box wallboard is ensured to be good. 6. Pre-splicing a steel sleeve box: and after the cofferdam is manufactured, pre-splicing is performed in time to check whether the dimensional deviation and the sealing occur in the manufacturing process, if the problem occurs, the cofferdam is processed, and finally, each index of the structure is ensured to meet the acceptance requirement. 7. Anticorrosive coating of the steel sleeve box: after the steel sleeve box is accepted, the special coating manufacturer performs the surface layer anticorrosion spraying work, the anticorrosion material is formed by compounding LT-SP-100 polymer composite materials through a certain molding method, and the mechanical properties of the anticorrosion composite materials meet the following table requirements.

Mechanical property index table of anti-corrosion composite material

Sequence number	Project	Unit (B)	Index (I)
				1	Specific gravity	g/cm3	1.5-2.0
2	Hardness of Babbit	HBa	≥45
				3	Water absorption rate	％	≤4
4	Tensile Strength	Mpa	≥150
				5	Tensile modulus	MPa	≥12500
6	Shear strength	Mpa	≥5
				7	Elongation at break	％	≥5

(1) Counting of anti-corrosion coating quantity of steel sleeve box

The engineering quantity statistics of the Niu Tianyang super bridge main bridge steel sleeve box corrosion-resistant composite material are shown in the following table:

engineering quantity statistics table for main bridge steel sleeve box anti-corrosion composite material

(2) Requirements for corrosion-proof coating conditions

(1) After the surface of the steel sleeve box is subjected to sand blasting and rust removal, anti-corrosion coating can be carried out; (2) the paint shop should be well ventilated and kept dry and should have a relative humidity of less than 80%. If the outdoor operation should be performed as well as possible in good weather conditions, the seasons with humid climate or low air temperature should be performed indoors. Outdoor operation should not be performed in rainy days, snowy days, foggy days and windy days; (3) the temperature should be 15-25 ℃, and the cross-hall wind is avoided, otherwise, the resin is easy to cure incompletely, and the surface of the product is sticky; (4) the water, electric and mechanical facilities and materials are completely prepared.

(3) The anti-corrosion coating construction process comprises the following steps: the process flow of the anti-corrosion coating construction is shown in figure 24. The construction method of the anti-corrosion coating comprises the following steps: (1) checking the substrate, and checking and accepting the substrate part to be preserved according to the following requirements by surface treatment; a. the outer surfaces of all the steel structures are required to be subjected to sand blasting rust removal treatment. b. The internal and external corners of the lining should be made into inclined planes or fillets (except for other requirements). c. Degreasing and drying, and cleaning the surface of the anti-corrosion part. d. The pipeline, the sleeve, the preformed hole and the embedded part which pass through the composite material anticorrosive layer are preset or reserved. (2) And (3) brushing under coat: after surface treatment, the base coat is painted for 1 to 2 times, each time about 0.1mm thick, and is naturally solidified, and the concave and convex corners are smeared into circular arc transition by using the putty, and the circular arc transition is flattened after solidification, so that the cloth can be pasted. (3) Cutting fiber cloth, namely, firstly selecting glass fiber cloth according to the requirement, and carefully checking the surface of the glass fiber cloth, wherein the glass fiber cloth cannot be wetted or polluted; b. when the fiber cloth is cut, the fiber cloth is directly cut according to the size, and the lap joint allowance is required to be reserved, and is 50mm generally; c. the cutting of the fiber cloth is suitable for the laying direction required by the lining part, the cutting position of the cloth is reduced as much as possible on the premise of not influencing the anti-corrosion requirement, and the cutting position of each layer is staggered when laying. d. When the fiber cloth is cut, the cloth is paved, and the fiber cloth should be used as soon as possible after cutting, if not used immediately, the fiber cloth needs to be wrapped by a clean plastic bag so as to avoid being affected by damp and further to influence the anti-corrosion quality. (4) The glue solution is prepared, namely, a container and a tool for preparing the glue solution are corrosion-resistant, clean and dry, and have no greasy dirt. (5) And (3) lining the fiber cloth, namely selecting corresponding materials such as resin, curing agent, fiber cloth, filler and the like according to design requirements. When the lining is attached, the lap joint between the upper part, the lower part, the left part and the right part of each piece of cloth is not smaller than 50mm. Each layer of the fiber cloth with the lining is constructed in a fish scale lapping mode, and each lining layer with the lining is continuously pasted with air pressure compaction, so that after the multi-layer construction is completed, air pressure compaction is carried out once. The principle of sticking cloth is mainly that a vertical surface is firstly provided with a rear plane, a vertical surface is firstly provided with a lower part, a vertical surface is firstly provided with a wall, and a bottom is firstly provided with a bottom. (6) And (3) curing and drying, surface modification and surface sizing, namely drying and curing for 24 to 48 hours at normal temperature after the fiber cloth is lined, and cleaning, repairing or repairing defects such as knots, burrs, bubbles and layering on the surface in time, and integrally spraying the surface sizing after the defects are qualified. And after the construction is finished, the construction is subjected to natural solidification and drying or heating treatment, and the construction can be delivered for acceptance after the solidification requirement is fully met. And (5) coating composite material quality inspection: (1) quality inspection should be carried out in the whole process of composite lining construction, the problem is found to be immediately trimmed, and the construction can be continued after the problem is qualified. (2) The construction area and thickness of the composite material are required to be constructed according to the requirements set by engineering content, and the thickness of each layer is required to be uniform; the surface of the composite material should be flat and smooth, and should not be allowed to have defects such as poor impregnation, resin nodules, poor curing, rugged, foaming, cracks, delamination, unfilled corners, edge drop and the like, and all the positions should be visually inspected to meet the following regulations: a. air bubble: the surface of the corrosion-resistant layer allows bubbles with a maximum bubble diameter of 5mm, and if less than three bubbles with diameters of not more than 5mm are used per square meter, the bubbles can not be repaired, otherwise, the bubbles should be scratched and repaired. b. Cracking: the surface of the corrosion-resistant layer has cracks with the depth of more than 0.5mm, and the middle reinforcing layer has no cracks with the depth of more than 2 mm. c. Relief (or wrinkles): the surface of the corrosion-resistant layer is smooth and flat, and the thickness of the concave-convex part of the reinforcing layer is not more than 20% of the thickness. d. Whitening: the corrosion-resistant layer should not have a whitening zone, and the maximum diameter of the whitening zone of the reinforcing layer is 50mm. (3) The edges of the composite material are clean and smooth, layering phenomenon is avoided, and the transition at the corners is smooth. (4) The physical properties of the composite material reach the national industry standard.

From the above, the steel box cofferdam consists of side plates (anti-collision boxes), bottom keels, bottom panels, bottom compartments, inner supports, hanging systems and the like, wherein Q235B steel is adopted as a main material, 22# and 23# main pier cofferdam side plates, namely the anti-collision boxes, are of double-wall structures, the side plates are simultaneously used as bearing platform templates, the plane outline dimension is 79m (transverse bridge direction) multiplied by 35.4m (forward bridge direction), the height is 10.8m, the wall thickness is 2-3 m, and the top elevation of the anti-collision box is +3.3m. For construction and simple to operate, the crashproof case is divided into A, B, C, D, E, F, G seven model sections, and each model has 4 sections, totally 28 sections, and the junction surface adopts high strength stainless steel bolted connection between the section, and the heaviest section is the G section, and the outline is long 7.804m, and is about 48.677t. The main materials of the side plates are steel plates with the thickness of 10mm, 12mm and 26mm and angle steel with the thickness of 140 multiplied by 90 multiplied by 10 mm.

To sum up: (1) The utility model provides a can dismantle temporary steel construction platform is adopted in installation of maintenance's forever to face structure cofferdam and anticollision facility to assemble, reduces marine hoist and mount risk, and the construction work efficiency is high. (2) The utility model provides a can dismantle temporary steel construction platform is adopted in installation of maintenance's forever to face structure cofferdam and anticollision facility can be with the installation accuracy improvement, improves installation quality. (3) A detachable and maintained permanent-face structural cofferdam and an anti-collision facility detect peripheral conditions of a steel casing before the cofferdam is lowered, check whether an obstacle for preventing the steel casing from sinking into place exists or not, and the steel casing can be lowered and installed into place smoothly at one time. (4) The utility model provides a can dismantle forever facing structure cofferdam and anticollision facility installation mainly adopts intelligent mechanized installation, can practice thrift personnel, machinery, temporary measure's input to the maximum extent, reduces the time limit for a project pressure that traditional mounting means brought. (5) The utility model provides a can dismantle maintenance's forever face structure cofferdam and anticollision facility installation adopts 350t hydraulic jack whole to transfer, ensures to transfer whole synchronism, has improved transfer efficiency and installation progress. (6) The invention can reduce the frequency of offshore operation, avoid causing secondary pollution, adopt the combination scheme of permanent face through the anticollision facility, namely the steel sleeve box for constructing the bearing platform remains after the bearing platform construction is finished, as the permanent anticollision facility, and upper portion hanging leg and inner panel of cofferdam are all installed with rubber spare, the outside of main pier sleeve box is installed with rubber fender, can protect the pier foundation, in order to prevent the sleeve box from directly colliding with the bearing platform and reduce the impact energy, simultaneously through the combination construction of permanent face, a large amount of extra temporary steel construction investment has been reduced, the detachable structure is convenient for later maintenance, reduce the replacement cost, and reduce the construction period, reduce the installation and maintenance safety risk.

While embodiments of the present invention have been shown and described above for purposes of illustration and description, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. A detachable and maintained permanent temporary structural cofferdam and an anti-collision facility installation method are characterized by comprising the following steps:

s1, preparing work before cofferdam assembly

(1) Steel jacketed tank bottom plate open hole inspection

Before the cofferdam is installed, the situation of the hole opening of the bottom plate of the cofferdam is further checked according to the actual measurement data of the steel casing, the bottom plate needs to pass through the steel casing of the bored pile during the cofferdam installation, and whether the reserved hole formed on the bottom plate is accurate or not is the key for affecting the stable sinking and accurate positioning of the steel sleeve box, so that the coordinates, ovality, gradient and inclination direction of the steel casing are required to be accurately measured, and the hole is formed on the bottom plate of the steel sleeve box according to the measurement result; (2) Detecting the peripheral conditions of the steel casing, wherein the detection content comprises the outer wall of the steel casing and the underwater condition in the sinking range of the steel casing, the detection method of the outer wall of the steel casing adopts round steel to process a steel ring with the inner diameter 50mm larger than the diameter of the steel casing, the steel ring is sleeved into the steel casing, the steel casing is kept horizontally lowered, and whether the periphery of the steel casing has an obstacle influencing the sinking of the steel casing is checked; (3) And (3) lofting the cofferdam installation position, and lofting the central axis, the important structure axis and the important side line position of the cofferdam according to the cofferdam installation position so as to ensure the accuracy of the cofferdam assembly and the lowering position.

S2, assembling and lowering the cofferdam, wherein in the step 1, the step I is as follows: after pile foundation construction is completed, pile inspection is qualified and grouting of a sounding pipe is completed, in order to ensure that the bottom of a steel sleeve box cofferdam is smoothly lowered to a position with a designed elevation of-7.5 m (the bottom of the cofferdam), measuring ropes are used for measuring the elevation of the sea bed before construction, part of a bored pile construction platform is dismantled, a long-arm excavator is arranged, the seabed or other obstacles affecting a deposition bed under the steel sleeve box cofferdam are cleaned in time, and the places where the excavator cannot excavate in place are cleaned by utilizing a grab bucket or an underwater dredging robot; step two: after the excavation of the cofferdam foundation pit is completed, measuring and checking the elevation of the seabed to meet the requirement of the lowering height of the cofferdam, and then connecting steel pile casings of No. 1, no. 4, no. 5, no. 9, no. 19, no. 20, no. 21, no. 22, no. 32, no. 37, no. 36 and No. 40 to the position of +10.5m, arranging brackets of a cofferdam assembly platform on the tops of the steel pile casings by using crawler cranes, and arranging a cofferdam assembly platform; step three: symmetrically hoisting cofferdam side plates (anti-collision boxes) by using two 150t crawler cranes or 100t gantry cranes according to the sequence of the middle part and the two ends, and finally closing the cofferdam side plates; step four: hoisting the bottom keels and the bottom plates to the brackets at the bottom of the steel bushing box according to the sequence from zone III to zone II to zone I by using two 150t crawler cranes or 100t gantry cranes, and welding the bottom plates of the bottom keels into a whole sequentially after the elevation, the plane position and the axis deviation of the bottom keels and the bottom plates are adjusted; step five: the bottom compartment is hung on the bottom panel in a segmented mode, and is placed at a designed position, then welded into a whole, welded with the bottom plate, then an inner support 2 (middle section) is installed, and finally the side plates, the cofferdam bottom compartment, the bottom panel and the keels are welded, so that the whole cofferdam system is formed into a whole; step six: installing a cofferdam on a high-connection steel pile casing, lowering a hanging distribution beam, arranging a 350t hydraulic jack at each lifting point (12 lifting points are arranged) on the lowering hanging distribution beam, installing a cofferdam guiding and limiting device on the inner side plate of the cofferdam corresponding to the steel pile casing (8 positions) at the corner position after the cofferdam is qualified, ensuring that a gap of 5cm is reserved between the joint surface of the cofferdam guiding and limiting device and the steel pile casing, filling the gap with hard rubber after the cofferdam guiding and limiting device is installed, binding the gap with the cofferdam guiding and limiting device by using iron wires, and simultaneously lifting and lowering all lifting points of the cofferdam: firstly, lifting the cofferdam integrally for 5cm, after checking that the conditions of the lifting points and all members are good, continuously lifting the cofferdam for 45cm, standing the cofferdam for 30min, leveling the cofferdam, and dismantling a cofferdam mounting platform; step seven: after the cofferdam mounting platform is dismantled, each point synchronously and slowly descends to the position of the designed elevation of-7.5 m (the bottom end of the cofferdam), when the cofferdam mounting platform descends, elevation observation points can be set at proper lifting points or scribing can be carried out on a suspender according to 5-10 cm scales, so that the stress of each lifting point is uniform when the steel sleeve box descends, the descending is required to be uniformly commanded, each operator is required to concentrate on, the mutual coordination is proper, the operation steps are consistent, and the synchronous and slow whole descending is realized.

2. The removable and serviceable permanent structural cofferdam and anti-collision facility installation method of claim 1, wherein: in the step (2) of the S1, the underwater condition in the sinking range of the steel sleeve box is mainly detected by a diver, in the step (I) of the S2, after the depth of the pier-position center seabed excavation meets the requirement, the rest construction platform is required to be dismantled, in the step (III) of the S2, the installation quality inspection of a water stop adhesive tape is required to be enhanced when the cofferdam side plates are assembled, water leakage caused by breakage, damage and dislocation is avoided, in the step (IV) of the S2, the size of a hole of the bottom plate at the pile position is determined based on the actual measured plane position and inclination of the pile foundation steel casing on site, so that the bottom plate is not clamped with the steel casing in the lowering process, in the step (V) of the S2, a temporary support structure is arranged for keeping stability in the assembly process of the cofferdam side plates (anti-collision box), the temporary support structure is connected with the cofferdam side plates through screw holes, and after the installation of the single side plates, the lower end of the temporary support structure is welded with the bottom plate of the assembly platform.

3. The removable and serviceable permanent structural cofferdam and anti-collision facility installation method of claim 1, wherein: in the step S2, a scaffold operation platform is required to be installed before construction, and each jack is controlled by a special person in the lowering process, so that synchronous lowering is ensured.