Concrete retaining wall and steel sheet pile combined cofferdam structure and construction method thereof

Abstract

The invention relates to a concrete retaining wall and steel sheet pile combined cofferdam structure and a construction method thereof, according to the cofferdam structure, three-face steel sheet piles are adopted in a shallow buried area of a seabed covering layer, concrete retaining walls are adopted in shoreside oblique rock and bare rock areas, and the steel sheet piles on the three faces and the concrete retaining walls jointly form the cofferdam structure with the four faces closed. The construction method comprises the following steps that groove milling and sand filling are conducted on the shallow buried area cofferdam foundation, brackets and a first layer of built-in supports are installed and assembled, steel sheet piles are sequentially inserted and driven with the inner supports as the guide, the supporting brackets are welded, and concrete retaining wall construction is conducted synchronously; a second-layer inner support and a support bracket are mounted after water pumping and mud suction of the cofferdam; a sand bag cushion layer is laid after the rock surface and sludge are cleaned, and bottom sealing concrete pouring is completed; and after the design strength is achieved, the second-layer inner support is dismantled, water pumping is conducted, and bearing platform construction is completed. The problems that under the conditions that a seabed covering layer in a near-shore area is shallow, and oblique rock and bare rock exist, steel sheet piles are difficult to insert and drive, and the buried depth is not enough are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering construction, and in particular to a concrete retaining wall and steel sheet pile combined cofferdam structure and a construction method thereof. Background Art

[0002] In recent years, my country's infrastructure construction has made great progress and played an important role in the stable development of the economy and society. Among them, the field of bridge construction is changing with each passing day. In order to ensure navigation safety, more and more bridge foundations are buried below the seabed, and cofferdam construction technology is widely used in bridges. Among them, steel sheet pile cofferdams are widely used due to their convenient construction, reliable support effect, long service life and reusability.

[0003] With the development of bridge construction, the increasingly complex geological conditions have made bridge foundation construction face many difficulties. For example, when constructing in offshore areas where the seabed cover is shallow and there are inclined rocks and bare rocks, the use of conventional steel sheet pile cofferdams has difficulties in driving in and the depth of penetration into the soil is insufficient. In addition, it is impossible to drive in the bare rock area close to the shore, which affects the progress of the project construction. Summary of the invention

[0004] The first object of the present invention is to provide a concrete retaining wall and steel sheet pile combined cofferdam structure.

[0005] The second object of the present invention is to provide a construction method of a concrete retaining wall and steel sheet pile combined cofferdam structure.

[0006] The first object of the present invention is achieved by: A cofferdam structure combining concrete retaining wall and steel sheet piles is characterized in that: SP-U400×170×15.5mm steel sheet piles on three sides are used in the shallow buried area of ​​the seabed cover layer, and concrete retaining walls are used in the inclined rock and bare rock areas on the shore. The steel sheet piles on three sides and the concrete retaining wall together form a cofferdam structure closed on four sides.

[0007] Furthermore, the width of the concrete retaining wall is 40 cm and the height is 3.6 m.

[0008] The second object of the present invention is achieved by: A construction method of a concrete retaining wall and a steel sheet pile combined with a cofferdam structure, the specific steps are as follows: Step 1: After the bored pile construction is completed, a rotary drilling rig is used on the drilling platform to mill the groove within the cofferdam foundation range of the shallow buried overburden layer area to the designed elevation, and sand is poured into the groove to the seabed surface; Step 2: dismantle the drilling platform and weld the cofferdam's assembled corbels at the corresponding elevation of the steel casing; Step 3: Use a crane to install the first layer of internal support of the cofferdam on the assembled corbels, and drive the steel sheet piles to the designed elevation with the first layer of internal support as the guide. The driving direction is from the upstream corner to the downstream corner, and then the connecting pipe is installed; Step 4: Chisel the rock surface flat to ensure that the concrete retaining wall is embedded in the rock surface not less than the design requirements, and anchor the steel bars and tie the steel bars of the concrete retaining wall on the rock surface, and then install the formwork. When installing the formwork, wrap the corner piles at the junction of the steel sheet piles and the concrete retaining wall to ensure that the corner piles extend into the concrete retaining wall, and then pour the concrete of the concrete retaining wall; Step 5: After the concrete of the concrete retaining wall reaches the designed strength, weld the supporting corbels at the corresponding elevation of the steel sheet piles, remove the assembled corbels; suck mud and pump water from the cofferdam to the top elevation of the designed cofferdam bottom, and install the second layer of internal support and supporting corbels; Step 6: When the water level outside the cofferdam is lower than the center elevation of the connecting pipe, the rock surface inside the cofferdam is cleaned to 20 cm below the top elevation of the cofferdam bottom seal, and the water and sludge in the cofferdam are sucked to the bottom elevation of the sandbag cushion layer; a 20 cm sandbag cushion layer is laid at the silt, filled and leveled, and the bottom seal concrete is poured to the designed elevation; Step 7: When the bottom seal concrete reaches the designed strength, remove the second layer of internal support and pump water from the cofferdam to the top elevation of the bottom seal of the cofferdam; Step 8: Cut off the steel casing, chisel off the pile head, tie up the steel bars and formwork of the foundation, and cast and maintain the foundation to complete the construction of the foundation.

[0009] The concrete retaining wall and steel sheet pile combined cofferdam structure and construction method thereof proposed by the present invention have the following beneficial effects compared with the existing steel sheet pile structure and construction method: The present invention adopts the structure and construction method of a concrete retaining wall plus steel sheet piles combined with a cofferdam, which ensures that the verticality of the buried steel sheet piles meets the requirements while avoiding the occurrence of damage to the steel sheet piles due to direct driving or insufficient driving depth, and solves the problems of difficulty in driving steel sheet piles and insufficient driving depth in the nearshore area where the seabed cover layer is shallow and there are inclined rocks and bare rocks. The method has the characteristics of strong adaptability, strong economy and high operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a plan view of the milling groove within the range of the cofferdam steel sheet pile of the present invention; Figure 2 It is a elevational layout diagram of the assembled corbels of the cofferdam of the present invention; Figure 3 It is a schematic diagram of the first layer of built-in support and steel sheet pile insertion of the cofferdam of the present invention; Figure 4 is a schematic diagram of a concrete retaining wall of the present invention; Figure 5It is a schematic diagram of the second layer of internal support and supporting corbels of the cofferdam; Figure 6 It is a schematic diagram of the cofferdam base cleaning and bottom sealing of the present invention; Figure 7 It is a schematic diagram of the removal of the second layer of inner support of the cofferdam of the present invention; Figure 8 It is a schematic diagram of the platform of the present invention; In the figure: 1. Drilling platform; 2. Rotary drilling rig; 3. Assembled corbels; 4. First-layer internal support; 5. Steel sheet piles; 6. Connecting pipes; 7. Concrete retaining wall; 8. Embedded reinforcement; 9. Support corbels; 10. Second-layer internal support; 11. Sandbag cushion; 12. Bottom concrete; 13. Capping platform; 14. Steel casing. DETAILED DESCRIPTION

[0011] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] The present invention provides a cofferdam structure combined with a concrete retaining wall and a steel sheet pile. The cofferdam structure uses SP-U400×170×15.5mm steel sheet piles 5 on three sides in the shallow buried area of ​​the seabed cover layer, and uses a concrete retaining wall 7 in the inclined rock and bare rock areas of the shore. The steel sheet piles 5 on three sides and the concrete retaining wall 7 together constitute a cofferdam structure closed on four sides. The width of the concrete retaining wall is 40 cm and the height is 3.6 m.

[0013] A construction method of a concrete retaining wall and a steel sheet pile combined with a cofferdam structure, the specific steps are as follows: Step 1: After the bored pile construction is completed, a rotary drilling rig 2 is used on the drilling platform 1 to mill a groove within the cofferdam foundation range of the shallow buried overburden layer area to the designed elevation, and sand is poured into the groove to the seabed surface; Step 2: dismantle the drilling platform 1 and weld the assembled bracket 3 of the cofferdam at the corresponding elevation of the steel casing 14; Step 3: Use a crane to install the first layer of built-in support 4 of the cofferdam on the assembled corbel 3, and drive the steel sheet pile 5 to the designed elevation with the first layer of built-in support 4 as a guide. The driving direction is from the upstream corner to the downstream corner, and the connecting pipe 6 is installed; Step 4: chisel the rock surface to ensure that the concrete retaining wall 7 is embedded in the rock surface not less than the design requirements, and anchor the steel bars 8 on the rock surface and tie the steel bars of the concrete retaining wall 7, and then install the formwork. When installing the formwork, the corner piles at the junction of the steel sheet piles 5 and the concrete retaining wall 7 must be wrapped to ensure that the corner piles extend into the concrete retaining wall 7, and then pour the concrete of the concrete retaining wall 7; Step 5: After the concrete of the concrete retaining wall 7 reaches the designed strength, weld the support bracket 9 at the corresponding elevation of the steel sheet pile 5, remove the assembled bracket 3; suck mud and pump water from the cofferdam to the top elevation of the designed cofferdam bottom, and install the second layer of internal support 10 and support bracket 9; Step 6: When the water level outside the cofferdam is lower than the center elevation of the connecting pipe 6, the rock surface inside the cofferdam is cleaned to 20 cm below the top elevation of the cofferdam bottom seal, and the water and sludge in the cofferdam are sucked to the bottom elevation of the sandbag cushion layer 11; a 20 cm sandbag cushion layer 11 is laid at the silt, filled and leveled, and the bottom seal concrete 12 is poured to the designed elevation; Step 7: When the bottom seal concrete 12 reaches the designed strength, the second layer of inner support 10 is removed, and water is pumped from the cofferdam to the top elevation of the bottom seal of the cofferdam; Step eight, cut off the steel casing 14, chisel off the pile head, tie up the steel bars of the cap 13 and install the formwork, and perform pouring and curing of the cap 13 to complete the construction of the cap 13.

[0014] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the art can make equivalent replacements or changes according to the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A concrete retaining wall and steel sheet pile combined cofferdam structure, characterized in that: SP-U400×170×15.5mm steel sheet piles are used on three sides in the shallow buried area of ​​the seabed cover layer, and concrete retaining walls are used in the inclined rock and bare rock areas on the shore. The steel sheet piles on three sides and the concrete retaining wall together form a cofferdam structure closed on four sides.

2. The concrete retaining wall and steel sheet pile combined cofferdam structure according to claim is characterized in that: The width of the concrete retaining wall is 40cm and the height is 3.6m.

3. A construction method of a concrete retaining wall and a steel sheet pile combined with a cofferdam structure, characterized in that: The specific steps are as follows: Step 1: After the bored pile construction is completed, a rotary drilling rig is used on the drilling platform to mill the groove within the cofferdam foundation range of the shallow buried overburden layer area to the designed elevation, and sand is poured into the groove to the seabed surface; Step 2: dismantle the drilling platform and weld the cofferdam's assembled corbels at the corresponding elevation of the steel casing; Step 3: Use a crane to install the first layer of internal support of the cofferdam on the assembled corbels, and drive the steel sheet piles to the designed elevation with the first layer of internal support as the guide. The driving direction is from the upstream corner to the downstream corner, and then the connecting pipe is installed; Step 4: Chisel the rock surface flat to ensure that the concrete retaining wall is embedded in the rock surface not less than the design requirements, and anchor the steel bars and tie the steel bars of the concrete retaining wall on the rock surface, and then install the formwork. When installing the formwork, wrap the corner piles at the junction of the steel sheet piles and the concrete retaining wall to ensure that the corner piles extend into the concrete retaining wall, and then pour the concrete of the concrete retaining wall; Step 5: After the concrete of the concrete retaining wall reaches the designed strength, weld the supporting corbels at the corresponding elevation of the steel sheet piles, remove the assembled corbels; suck mud and pump water from the cofferdam to the top elevation of the designed cofferdam bottom, and install the second layer of internal support and supporting corbels; Step 6: When the water level outside the cofferdam is lower than the center elevation of the connecting pipe, the rock surface inside the cofferdam is cleaned to 20 cm below the top elevation of the cofferdam bottom seal, and the water and sludge in the cofferdam are sucked to the bottom elevation of the sandbag cushion layer; a 20 cm sandbag cushion layer is laid at the silt, filled and leveled, and the bottom seal concrete is poured to the designed elevation; Step 7: When the bottom seal concrete reaches the designed strength, remove the second layer of internal support and pump water from the cofferdam to the top elevation of the bottom seal of the cofferdam; Step 8: Cut off the steel casing, chisel off the pile head, tie up the steel bars and formwork of the foundation, and cast and maintain the foundation to complete the construction of the foundation.

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