Steel casing cofferdam anchoring operation method for deepwater hard rock area

Abstract

The invention discloses a steel casing cofferdam anchoring operation method for a deepwater hard rock area, and belongs to the technical field of overwater construction platforms, a cofferdam, a steel casing and a drilling platform are included, before the cofferdam is lowered, bed rock cleaning is completed through layered excavation and impact treatment, a karst cave is filled with an underwater concrete ball pulling method, and the stability of a foundation is improved. When the steel casing and the drilling platform pipe pile are installed, the bottom adjusting device is used for adjusting the angle, ensuring the perpendicularity, shortening the construction period and reducing the labor cost and the safety risk. The pipe piles are fixedly connected with the cofferdam through a connecting system. According to the method, the bed rock is treated, the impact resistance and disturbance resistance can be improved, the service life of the platform is prolonged, and reliable support is provided for bridge construction. Accurate positioning and layered excavation are achieved, disturbance to rock stratums and karst caves is reduced, the influence on the ecological environment is reduced, and meanwhile the construction quality and efficiency are guaranteed.

Description

Technical Field

[0001] The invention relates to a steel casing cofferdam anchoring operation method used in deep water hard rock areas, belonging to the technical field of water construction platforms. Background Art

[0002] The main pier foundation of a long-span bridge across a large river usually adopts a large-diameter pile group foundation. When the conditions at some sites are exposed hard rock and the foundation structure is designed as a deep-buried cap, the pipe piles of the water drilling platform and the open steel casing of the main pier pile foundation are often difficult to drive to the designed depth. In this case, the bearing capacity of the platform will be seriously affected. If other reinforcement measures are adopted, not only will the construction process be complicated, but the construction cost will also be significantly increased.

[0003] At present, in the face of deep water conditions and karst development environment, traditional construction methods are difficult to guarantee the force requirements of the construction platform during use and the stability during the process under the cofferdam, and the construction process is complicated. The traditional process adopts: drilling platform erection, bored pile construction, drilling platform dismantling, cofferdam lowering, and foundation construction. The process has a long construction period.

[0004] Therefore, it is necessary to design a steel casing cofferdam anchoring operation method for deep water hard rock areas, which solves the problems of high construction cost and great construction difficulty in deep water hard rock areas. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a steel casing cofferdam anchoring operation method for deep water hard rock areas, which solves the problems of high construction cost and great construction difficulty in deep water hard rock areas.

[0006] The technical problem to be solved by the present invention is achieved by adopting the following technical solution: a method for anchoring a cofferdam platform in a deep-water hard rock area,

[0007] Including cofferdam, steel casing, drilling platform,

[0008] The steel casing is arranged inside the cofferdam, and the drilling platform is arranged on the top of the steel casing.

[0009] The laying and anchoring of the cofferdam and the drilling platform include the following steps:

[0010] Step 1: Use underwater excavation method to process the foundation pit within the scope of laying the cofferdam and the drilling platform, complete the layered excavation of the riverbed bedrock, and clean it;

[0011] Step 2: Locate the foundation pit of the cofferdam and perform additional impact treatment on the incompletely revealed karst caves;

[0012] Step 3: Backfill the cave with concrete using the underwater concrete ball extraction method;

[0013] Step 4, cleaning the silt in the foundation pit of the cofferdam and leveling it, and lowering the cofferdam;

[0014] Step 5: Throwing sandbags at the blade foot within the range of the cofferdam to stop leakage;

[0015] Step 6: Install the steel casing and the drilling platform pipe pile structure, and ensure the verticality of the steel casing and the pipe pile by the bottom adjustment device;

[0016] Step 7: Connect the steel casing, the cofferdam and the platform pipe piles, and connect the steel casing, the cofferdam and the platform pipe piles;

[0017] Step 8: Install the bottom cover platform and pour the bottom cover concrete of the cofferdam;

[0018] Step 9: Install the beam and corbel;

[0019] Step 10: Lift the beams in sections to the designed position and connect them into a whole by bolts;

[0020] Step 11: The girders are connected via the transverse connecting system;

[0021] Step 12: Lay the bridge deck steel and patterned steel plates on the beam to complete the drilling platform installation.

[0022] Preferably, in step 3, the underwater concrete ball extraction method for dealing with complex karst caves includes pre-burying pipes before underwater concrete pouring and pouring grouting material into the pipes.

[0023] Preferably, in step 4, the cofferdam is a round-ended prismatic hexagon consistent with the base structure, and is vertically divided into three sections. The cofferdam adopts a double-wall cofferdam, which is composed of a panel, a stiffening plate, and a horizontal ring plate. The first section from the bottom is provided with a blade foot, and the vertical sections are welded to connect the height, and flanges are provided at the section connections; the cofferdam is assembled into whole sections, transported to the tonnage by barge, hoisted to the installation position, assembled into a whole in sections, poured with blade foot concrete, poured with water to sink, and positioned and anchored.

[0024] Preferably, in step 6, reinforcing ribs are welded on the outer side of the bottom section of the steel casing, and beam corbel units are welded on the outer side of the top section.

[0025] Preferably, the steel casing is formed by circumferential roll welding of steel plates with a wall thickness of 4 mm, and small steels are spot welded at the four corners of the bottom as a leveling measure.

[0026] Preferably, the steel casing is transported to the bridge site by barge, the bottom section of the steel casing is hoisted by a floating crane and moved to the designed position, the inclination is adjusted and fixed, and then the upper steel casing is hoisted section by section and welded until all the steel casings are installed.

[0027] Preferably, the inclination of the steel casing is monitored by an angle gauge to ensure that the verticality meets the requirements.

[0028] The beneficial effects of the present invention are:

[0029] The present invention optimizes the operation method and platform for anchoring steel casing cofferdams in deep-water hard rock areas, performs impact treatment on the bedrock of the riverbed before lowering the cofferdam, and excavates in layers. The karst cave is filled with concrete using the underwater concrete ball extraction method. When installing the steel casing and the drilling platform pipe piles, an adjustment device is provided at the bottom, which can adjust the angle between the steel casing and the drilling platform pipe piles, shorten the construction period of the cofferdam, and reduce labor costs and safety risks. The pipe piles and the cofferdam are connected and fixed by a connecting system, which can improve the impact resistance and anti-disturbance ability of the cofferdam platform, extend the service life of the structure, and provide support for subsequent bridge construction. Through layered excavation and precise positioning, the disturbance to the karst caves and rock formations can be reduced, and the impact on the surrounding ecological environment can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the present invention.

[0031] Figure 2 It is a plan layout diagram of the present invention.

[0032] Figure 3 It is a schematic diagram of the installation of the connection system between the steel casings of the present invention.

[0033] Figure 4 It is a structural schematic diagram of the bottom of the steel casing of the present invention.

[0034] In the figure: 1-rotary drilling rig, 2-drilling platform, 3-girder, 4-corbel, 5-distribution beam, 6-steel casing connection system, 7-connection system, 8-cofferdam, 9-steel casing, 10-circumferential welded steel bar ring. DETAILED DESCRIPTION

[0035] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below in conjunction with specific embodiments.

[0036] Example 1

[0037] like Figure 1-Figure 4 shown.

[0038] A cofferdam platform anchoring operation method for deep-water hard rock areas comprises a cofferdam 8, a steel casing, and a drilling platform 2. The steel casing 9 is arranged inside the cofferdam 8, and the drilling platform 2 is arranged on the top of the steel casing.

[0039] The laying and anchoring of the cofferdam 8 and the drilling platform 2 include the following steps:

[0040] Step 1: Use underwater excavation method to process the foundation pit within the laying range of the cofferdam 8 and the drilling platform 2, complete the layered excavation of the riverbed bedrock, and clean it;

[0041] Step 2: Locate the foundation pit of the cofferdam 8 and perform additional impact treatment on the karst caves that have not been fully revealed;

[0042] Step 3: Backfill the cave with concrete using the underwater concrete ball extraction method;

[0043] Step 4, cleaning the silt in the foundation pit of the cofferdam 8 and leveling it, and lowering the cofferdam 8;

[0044] Step 5: Throw sandbags to fill the blade foot within the range of the cofferdam 8 to stop leakage;

[0045] Step 6: Install the steel casing and the drilling platform pile structure, and ensure the verticality of the steel casing and the pile through the bottom adjustment device;

[0046] Step 7: Connect the steel casing, cofferdam 8 and platform piles, and connect the steel casing, cofferdam 8 and platform piles with a connection system 7;

[0047] Step 8: Install the bottom cover platform and pour the bottom cover concrete of the cofferdam 8;

[0048] Step 9: Install beam 3 and corbel 4;

[0049] Step 10: hoist the beam 3 to the designed position in sections and connect them into a whole by bolts;

[0050] Step 11: The beams 3 are connected via a transverse connection system 7;

[0051] Step 12: Lay the bridge deck steel and patterned steel plate on the beam 3 to complete the erection of the drilling platform 2.

[0052] The above is a method for anchoring cofferdam platforms used in deepwater hard rock areas.

[0053] In step 1, it is necessary to conduct a review measurement of the elevation control network and the plane coordinate control network before construction. GPS is used to lay out the channel dredging area and the main pier excavation area of ​​the bridge location, and buoys are set at the boundaries to indicate the scope.

[0054] The bedrock is treated by layered and gradual excavation, and the excavation depth is controlled to avoid secondary disturbance of the cave. The excavated rock and soil are cleaned by transport ships to ensure that the foundation pit is clean and free of silt.

[0055] In step 2, the foundation pit needs to be located and the caves that have not been fully revealed need to be supplemented with impact treatment.

[0056] For small caves, the top impact can be enlarged to facilitate the backfilling and pouring of underwater concrete.

[0057] In step 3, the karst cave located in the foundation pit needs to be filled with concrete. The concrete is poured in layers in the karst cave through the ball pulling device. The ball pulling device is used to achieve uniform distribution of the concrete and gradually fill the interior of the karst cave.

[0058] In some areas, there are many caves with complex contours. For particularly complex caves (such as areas with sunken bottoms or overly complex contours), a plastic pipe is embedded before underwater concrete pouring. After the concrete is initially solidified, grouting material is poured through the embedded pipe to further fill the gaps and ensure compactness.

[0059] In step 4, the bottom of the foundation pit needs to be leveled and cleaned, and the silt and debris within the foundation pit need to be removed to ensure that the bottom of the foundation pit is flat, laying the foundation for the lowering of the steel cofferdam.

[0060] The cofferdam 8 is spliced ​​in sections at the shore site, and the sections are connected and fixed by welding.

[0061] The structure of the cofferdam 8 is a round-ended prismatic hexagon consistent with the foundation structure, and is divided into 3 sections in the vertical direction. In this embodiment, the average size of the cofferdam 8 is 35.97m×18.9m, the height of each section is 12m, the defense water level of the cofferdam 8 is +70.8m, and the top elevation of the cofferdam 8 is +73.667m. The cofferdam 8 adopts a double-wall cofferdam 8 structure, which is composed of a panel, a stiffening plate, and a horizontal ring plate. From the bottom to the top, the first section is provided with a blade foot, and the vertical section is welded to connect the height, and a flange is provided at the connection of the section; the cofferdams 8 of different sections are fixed by welding flanges. The cofferdam 8 is assembled into a whole section, transported to the tonnage by barge, and hoisted to the installation location, assembled into a whole section by section, poured with blade foot concrete, and water is poured inside the cofferdam 8 and positioned and anchored.

[0062] Reference Figure 1 A distribution beam 5 is arranged on the top of the cofferdam 8. The cofferdam 8 has two layers, and a distribution beam 5 is arranged on the top of the cofferdam 8 to connect and fix it.

[0063] In step 6, the outer side of the bottom section of the steel casing is welded with reinforcing ribs, and the outer side of the top section of the steel casing is welded with a beam bracket unit. The steel casing is formed by circumferential roll welding of a steel plate with a wall thickness of 4mm, and small steels are welded at several corners at the bottom as a leveling measure.

[0064] Installation of steel casing 9 and pipe piles,

[0065] In this embodiment, the pipe pile is connected to the steel casing 6, and the pipe pile and the steel casing 6 are installed according to the designed position. An adjustment device is provided at the bottom of the steel casing 6, which can adjust the inclination of the steel casing 6 to ensure that the steel casing 6 can meet the design requirements.

[0066] In this embodiment, the bottom adjustment device of the steel casing 6 is a certain length of steel welded at the four diagonal positions at the bottom of the steel casing 6. When adjusting the verticality of the steel casing 6, the underwater diver can conveniently fix the verticality by padding to meet the design requirements.

[0067] Specifically, the steel casing 6 is transported to the bridge site by barge, the bottom section of the steel casing 6 is hoisted by floating crane and moved to the designed position, the inclination is adjusted and fixed, and the upper steel casing 6 is hoisted section by section and welded until the installation of the used steel casing 6 is completed. When the steel casing 6 is connected and welded, the line type connected with the pre-buried steel casing 6 is strictly controlled and the verticality is re-measured.

[0068] In this embodiment, the inclination of the steel casing 6 is monitored by an angle meter to ensure that the verticality meets the requirements. The length of the steel casing 6 is relatively long, and the inclination is calculated according to the length of the empty pile. The steel casing 6 is temporarily fixed with the cofferdam 8 to prevent the bottom concrete from disturbing the steel casing 6.

[0069] In this embodiment, the foundation excavation contour line is laid out by GPS before construction, the construction record is recorded, the original rock surface is measured before dredging, and the process measurement is performed at least once a week during the construction process. Before construction, the river channel is scanned using an acoustic wave detector, the riverbed elevation in the area is checked, and the excavation depth is determined in combination with the rock layer thickness, the measured data and the technical excavation elevation. According to the difference in excavation depth, the excavation is carried out in different areas. In step 4, during the lowering of the cofferdam 8, the position of the cofferdam 8 is strictly measured, fine-tuned, and appropriate measurement points are set up around the cofferdam 8.

[0070] In step 6, the bored platform pipe piles are designed according to the platform load. In this embodiment, the bored platform pipe piles are in the form of φ630 pipe piles, which are shared with the pile foundation steel casing. The beam 3 installed on the pipe piles is installed on the corbel 4 of the steel casing.

[0071] In this embodiment, the drilling platform 2 is installed on the top of the cofferdam 8, and the bottom of the drilling platform 2 is provided with a free beam 3 and a corbel 4 for connection and support. A rotary drilling rig 1 is arranged on the top of the drilling platform 2. The steel casings 9 are connected by a steel casing connection system 6; and the connection system 7 is connected to the cofferdam 8.

[0072] In step 7, when the cofferdam 8 is connected to the pipe pile, it should be welded at the position with the stiffening rib and must not be welded only on the empty cabin panel to prevent deformation or strain.

[0073] In step 8, the bottom concrete pouring adopts the ball pulling method, and the elevation is strictly controlled in sequence according to the pouring order to ensure the quality of the concrete bottom seal.

[0074] Reference Figure 2 , the plan layout of the above-water pipe piles (inner circle) and the steel casing (outer circle). The steel casings are connected by pipe piles, and the steel casings are connected to the cofferdam 8 by section steel.

[0075] Reference Figure 4 A reversing welded steel bar ring is provided at the bottom of the bottom concrete and the steel casing 6, which can increase the bond strength between the bottom concrete and the steel casing 6 and enhance the anti-disturbance performance.

[0076] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for anchoring a cofferdam platform in a deep-water hard rock area. Including cofferdam, steel casing, drilling platform, The steel casing is arranged inside the cofferdam, and the drilling platform is arranged on the top of the steel casing. Features: The laying and anchoring of the cofferdam and the drilling platform include the following steps: Step 1: Use underwater excavation method to process the foundation pit within the scope of laying the cofferdam and the drilling platform, complete the layered excavation of the riverbed bedrock, and clean it; Step 2: Locate the foundation pit of the cofferdam and perform additional impact treatment on the incompletely revealed karst caves; Step 3: Backfill the cave with concrete using the underwater concrete ball extraction method; Step 4, cleaning the silt in the foundation pit of the cofferdam and leveling it, and lowering the cofferdam; Step 5: Throwing sandbags at the blade foot within the range of the cofferdam to stop leakage; Step 6: Install the steel casing and the drilling platform pipe pile structure, and ensure the verticality of the steel casing and the pipe pile by the bottom adjustment device; Step 7: Connect the steel casing, the cofferdam and the platform pipe piles, and connect the steel casing, the cofferdam and the platform pipe piles; Step 8: Install the bottom cover platform and pour the bottom cover concrete of the cofferdam; Step 9: Install the beam and corbel; Step 10: Lift the beams in sections to the designed position and connect them into a whole by bolts; Step 11: The girders are connected via the transverse connecting system; Step 12: Lay the bridge deck steel and patterned steel plates on the beam to complete the drilling platform installation.

2. The anchoring method for a cofferdam platform in a deep-water hard rock area according to claim 1, characterized in that: In step 3, the underwater concrete ball extraction method for dealing with complex karst caves includes pre-burying pipes before underwater concrete pouring and pouring grouting material into the pipes.

3. The anchoring method for a cofferdam platform in a deep-water hard rock area according to claim 1, characterized in that: In step 4, the cofferdam is a round-ended prism-shaped hexagon consistent with the base structure, and is divided into three sections vertically. The cofferdam adopts a double-wall cofferdam, which is composed of a panel, a stiffening plate, and a horizontal ring plate. The first section from the bottom is provided with a blade foot, and the vertical sections are welded to connect the height, and flanges are provided at the section connections; the cofferdam is assembled into whole sections, transported to the tonnage by barge, hoisted to the installation position, assembled into a whole in sections, poured with blade foot concrete, poured with water to sink and positioned and anchored.

4. The method for anchoring a cofferdam platform in a deep-water hard rock area according to claim 1, characterized in that: In step 6, reinforcing ribs are welded to the outside of the bottom section of the steel casing, and beam corbel units are welded to the outside of the top section.

5. The anchoring method for a cofferdam platform in a deep-water hard rock area according to claim 4, characterized in that: The steel casing is formed by circumferential roll welding of steel plates with a wall thickness of 4 mm, and small steels are welded at the four corners of the bottom as a leveling measure.

6. The anchoring method for a cofferdam platform in a deep-water hard rock area according to claim 4, characterized in that: The steel casing is transported to the bridge site by barge, and the bottom section of the steel casing is hoisted by floating crane and moved to the designed position, and the inclination is adjusted and fixed, and then the upper steel casing is hoisted section by section and welded until all the steel casings are installed.

7. The anchoring method for a cofferdam platform in a deep-water hard rock area according to claim 6, characterized in that: The inclination of the steel casing is monitored by an angle gauge to ensure that the verticality meets the requirements.

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