A construction method of a steel sheet pile cofferdam in a rock area with a thin covering layer

Abstract

This invention provides a method for constructing sheet pile cofferdams in rocky areas with thin overburden. The method involves drilling pre-holes at designed locations on a construction platform using a pre-drilling device, followed by backfilling the boreholes with red clay. Multiple guiding mechanisms are installed inside the construction platform, and sheet piles are then driven using a pile-driving device, with the sheet piles positioned against the guiding mechanisms during driving. High-pressure jet grouting is used to seal and reinforce the sheet piles from the bottom upwards. Water is pumped out of the cofferdam, and internal supports are installed layer by layer from top to bottom. The foundation pit is excavated to the designed elevation, a cushion layer is poured, and the foundation cap is constructed. Sand is backfilled between the foundation cap and the sheet piles, and the bottom layer of internal supports is removed before constructing the pier body. The method of pre-drilling, backfilling, and high-pressure jet grouting establishes a consolidated system between the sheet piles and the rock. Backfilling sand between the foundation cap and the sheet pile cofferdam completes the first system transition. This method features a simple structure, clear stress distribution, and safe construction.

Description

Technical Field

[0001] This invention relates to the technical field of bridge engineering, and specifically to a method for constructing steel sheet pile cofferdams in rock areas with thin overburden. Background Technology

[0002] Cofferdams are frequently used during the construction of bridge piers. In soil-rich environments, steel sheet pile or steel pipe pile cofferdams are often used to block water and retain soil. In water bodies with rocky strata, excavation is generally unnecessary, and steel caisson cofferdams are commonly used. However, for water bodies requiring excavation and with rocky strata, using steel caisson cofferdams can lead to difficulties in lowering the cofferdam. Furthermore, steel caisson cofferdams have complex structures, require large quantities of steel, have fixed structural forms after fabrication, long processing cycles, poor versatility, and high construction costs. Summary of the Invention

[0003] The main objective of this invention is to provide a construction method for steel sheet pile cofferdams in rock areas with thin overburden, thereby solving the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention includes the following steps:

[0005] S1. On the construction platform, a pilot hole is drilled at the designed location using a pilot hole drilling device. After the pilot hole is completed, red clay is backfilled into the drill hole.

[0006] S2. Install multiple guiding mechanisms inside the construction platform, and then drive steel sheet piles with pile driving equipment. During the driving process, the steel sheet piles are positioned against the guiding mechanisms.

[0007] S3. High-pressure jet grouting is used to seal and reinforce the steel sheet pile from the bottom upwards.

[0008] S4. Pump water out of the cofferdam and install internal supports layer by layer from top to bottom;

[0009] S5. Excavate the foundation pit to the design elevation, pour the cushion layer, and construct the foundation cap;

[0010] S6. Backfill sand between the pile cap and the sheet piles, and construct the pier body after removing the lowest layer of inner support;

[0011] S7. During the construction of the pier layer by layer, the internal supports are removed layer by layer, and the steel sheet piles are connected to the pier by installing and converting the internal supports.

[0012] Preferably, the guiding mechanism is set in two layers within the construction platform. The upper guiding mechanism is fixed on the distribution beam and main crossbeam of the construction platform, and the lower guiding mechanism is fixed on the steel pipe pile.

[0013] Preferably, the lower guide beam in the guiding mechanism is provided with a slidingly adjustable upper guide beam, and a limiting beam is fixed on the upper guide beam. The limiting beams of multiple guiding mechanisms in each layer are connected end to end.

[0014] Preferably, the lower guide beam and the upper guide beam are provided with corresponding locking holes, and the bolts are locked in different locking holes by staggered locking, thereby adjusting the distance between the upper guide beam and the lower guide beam.

[0015] Preferably, one end of the lower guide beam in the upper guide mechanism is fixed to the distribution beam, and the bottom of the lower guide beam is fixed to the main cross beam by diagonal bracing;

[0016] One end of the lower guide beam in the lower guide mechanism is fixed to the steel pipe pile, and the bottom of the lower guide beam is fixed to the steel pipe pile by diagonal bracing.

[0017] Preferably, when the pier body encounters internal support obstruction during construction, multiple embedded parts are pre-embedded on both sides of the lower pier body, and one end of the conversion internal support is fixed to the embedded part, and the other end is fixed to the steel sheet pile.

[0018] Preferably, multiple anchor bars in the embedded part are embedded in the pier body, and anchor plates are fixed at the ends of the multiple anchor bars, with the anchor plates being fixedly connected to the conversion inner support.

[0019] Preferably, the anchor plate is fixedly connected to the anchor bar by a nut and a tapered sleeve, and the outer side of the anchor plate is on the same side as the outer side of the pier body.

[0020] Preferably, multiple stiffening plates are fixed between the periphery of the conversion inner support and the anchor plate.

[0021] This invention provides a construction method for sheet pile cofferdams in rocky areas with thin overburden. The method employs pre-drilling, backfilling, and high-pressure jet grouting to solidify the sheet piles with the rock. Sand is then backfilled between the pile cap and the sheet pile cofferdam to complete the initial system transition. A guiding mechanism provides positioning support for the sheet piles, ensuring accurate driving. By using a conversion inner support, when construction of the pier is restricted, the inner support can be removed and the sheet piles can be repositioned and supported against the pier, ensuring the stability of the sheet piles. This method features a simple structure, clear stress distribution, and safe construction. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 This is a schematic diagram of the hole backfilling process of the present invention;

[0024] Figure 2 This is a schematic diagram of the steel sheet pile driven according to the present invention;

[0025] Figure 3 This is a schematic diagram of the construction of the foundation of this invention;

[0026] Figure 4 This is a schematic diagram of the backfill sand and pier construction of the present invention;

[0027] Figure 5 This is a top view of the installation of the conversion internal support in the steel sheet pile of the present invention;

[0028] Figure 6 This is the present invention. Figure 5 Sectional view of AA;

[0029] Figure 7 This is the present invention. Figure 6 Enlarged view b in the middle;

[0030] Figure 8 This is the present invention. Figure 7 CC section view;

[0031] Figure 9 This is the present invention. Figure 7 Enlarged view d in the middle;

[0032] Figure 10 This is a top view of the guide mechanism installation in the construction platform of this invention;

[0033] Figure 11 This is a schematic diagram showing the connection between the upper guiding mechanism and the construction platform of the present invention;

[0034] Figure 12 This is a schematic diagram showing the connection between the lower guiding mechanism and the construction platform of the present invention;

[0035] In the diagram: 1. Construction platform; 101. Cover plate; 102. Steel pipe pile; 103. Distribution beam; 104. Main crossbeam; 2. Drilling equipment; 3. Conveying equipment; 4. Drilling hole; 5. Red clay; 6. Piling equipment; 7. Guiding mechanism; 701. Upper guide beam; 702. Lower guide beam; 703. Diagonal brace; 704. Bolt; 8. Steel sheet pile; 9. Internal support; 10. Pier cap; 11. Sand; 12. Pier body; 13. Embedded parts; 1301. Anchor bar; 1302. Anchor plate; 1303. Conical sleeve; 1304. Nut; 14. Conversion internal support; 15. Stiffening plate; 16. Limiting beam. Detailed Implementation

[0036] Example 1

[0037] like Figures 1-12 As shown, a method for constructing a steel sheet pile cofferdam in a rocky area with a thin overburden layer includes the following steps:

[0038] S1. On the construction platform 1, a pilot hole is drilled at the designed position using the pilot hole equipment 2. After the pilot hole is completed, red clay 5 is backfilled into the drill hole 4.

[0039] S2. Install multiple guide mechanisms 7 inside the construction platform 1, and then drive steel sheet piles 8 through the pile driving equipment 6. During the driving process, the steel sheet piles 8 are positioned against the guide mechanisms 7.

[0040] S3. High-pressure jet grouting is used to seal and reinforce the bottom of sheet pile 8 from top to bottom.

[0041] S4. Pump water out of the cofferdam and install the inner supports 9 layer by layer from top to bottom;

[0042] S5. Excavate the foundation pit to the design elevation, pour the cushion layer, and construct the 10-meter-high foundation cap.

[0043] S6. Backfill sand 11 between the pile cap 10 and the sheet pile 8, and construct the pier body 12 after removing the lowest layer of inner support 9.

[0044] During the construction of S7 and pier 12 layer by layer, the inner support 9 is removed layer by layer, and the steel sheet pile 8 is connected to the pier 12 by installing and converting the inner support 14.

[0045] Before driving the sheet piles 8, a guide mechanism 7 is installed and the guide support surface is adjusted to reach the set position. During driving, the sheet piles 8 slide against the guide mechanism 7, ensuring the accuracy of the sheet pile driving. A pre-drilling and high-pressure jet grouting method is used to form a consolidation system between the sheet piles 8 and the rock. Sand 11 is backfilled between the pier cap 10 and the sheet pile 8 cofferdam to complete the first system conversion. During the construction of the pier body 12, the internal support 9 needs to be removed to create space. Embedded parts 13 are installed on both sides of the pier body 12. The sheet piles 8 and the embedded parts 13 are connected by the conversion of the internal support 14, thereby transferring the support force on the sheet piles 8 and ensuring the stability of the sheet pile 8 cofferdam.

[0046] Example 2

[0047] like Figures 1-12 As shown in Example 1, the guiding mechanism 7 is configured in two layers within the construction platform 1. The upper guiding mechanism 7 is fixed to the distribution beam 103 and the main crossbeam 104 of the construction platform 1, while the lower guiding mechanism 7 is fixed to the steel pipe pile 102. This double-layer structure provides precise positioning, excellent guiding effect, and is adjustable, making it highly adaptable.

[0048] Preferably, the lower guide beam 702 in the guide mechanism 7 is provided with a slidingly adjustable upper guide beam 701, and a limiting beam 16 is fixed on the upper guide beam 701. The limiting beams 16 between multiple guide mechanisms 7 in each layer are connected end to end. With this structure, the guide mechanism 7 serves as the guide connection point, and the limiting beams 16 form guide lines by connecting multiple connection points. The double-layer structure can form a guide surface, making the positioning and guidance more accurate and reliable.

[0049] Preferably, the lower guide beam 702 and the upper guide beam 701 are provided with corresponding locking holes. These are secured in different locking holes by staggered bolts 704, thereby adjusting the distance between the upper guide beam 701 and the lower guide beam 702. With this structure, the upper guide beam 701 slides against the lower guide beam 702 and is fixed by staggered bolts 704 in different locking holes, thus adjusting the position of the guide surface and ensuring accurate positioning and guidance of the sheet pile 8.

[0050] Preferably, one end of the lower guide beam 702 in the upper guide mechanism 7 is fixed to the distribution beam 103, and the bottom of the lower guide beam 702 is fixed to the main cross beam 104 by the diagonal brace 703;

[0051] In the lower guide mechanism 7, one end of the lower guide beam 702 is fixed to the steel pipe pile 102, and the bottom of the lower guide beam 702 is fixed to the steel pipe pile 102 by the diagonal brace 703. This structure is simple and the installation is stable and reliable.

[0052] Preferably, when the pier body 12 encounters obstruction from the internal supports 9 during construction, multiple embedded parts 13 are pre-embedded on both sides of the lower pier body 12. One end of the converted internal support 14 is fixed to the embedded part 13, and the other end is fixed to the sheet pile 8. With this structure, the sheet pile 8 has multiple layers of internal supports 9 inside, which play a role in supporting and reinforcing the cofferdam. However, during the construction of the pier body 12, the internal supports 9 will cause obstruction. In order to ensure the stability of the cofferdam while avoiding the construction of the pier body 12, the sheet pile 8 is supported against the pier body 12 by converting the internal supports 14. The operation is simple and convenient.

[0053] Preferably, multiple anchor bars 1301 in the embedded part 13 are embedded in the pier body 12, and anchor plates 1302 are fixed at the ends of the multiple anchor bars 1301. The anchor plates 1302 are fixedly connected to the conversion inner support 14. With this structure, the anchor plates 1302 are fixed on the pier body 12 as a connection surface, and the conversion inner support 14 is fixedly connected to the anchor plates 1302, making the connection more stable and reliable.

[0054] Preferably, the anchor plate 1302 is fixedly connected to the anchor bar 1301 by a nut 1304 and a tapered sleeve 1303, and the outer side of the anchor plate 1302 is on the same side as the outer side of the pier body 12.

[0055] Preferably, multiple stiffening plates 15 are fixed between the inner support 14 and the anchor plate 1302 on its periphery. This makes the connection more stable and reliable.

[0056] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for constructing a steel sheet pile cofferdam in a rock area with a thin overburden layer, characterized by: Includes the following steps: S1. On the construction platform (1), a pilot hole is drilled at the designed position using a pilot hole device (2). After the pilot hole is completed, red clay (5) is backfilled into the drill hole (4). S2. Install multiple guide mechanisms (7) inside the construction platform (1), and then drive steel sheet piles (8) through the pile driving equipment (6). During the driving process, the steel sheet piles (8) are positioned against the guide mechanism (7). The guide mechanism (7) is set in two layers inside the construction platform (1). The upper guide mechanism (7) is fixed on the distribution beam (103) and the main cross beam (104) of the construction platform (1), and the lower guide mechanism (7) is fixed on the steel pipe pile (102). The lower guide beam (702) of the guide mechanism (7) is provided with a slidingly adjustable upper guide beam (701), and a limiting beam (16) is fixed on the upper guide beam (701). The limiting beams (16) between multiple guide mechanisms (7) in each layer are connected end to end. The lower guide beam (702) and the upper guide beam (701) are provided with corresponding locking holes. They are locked in different locking holes by bolts (704) in a staggered manner, thereby adjusting the distance between the upper guide beam (701) and the lower guide beam (702). One end of the lower guide beam (702) in the upper guide mechanism (7) is fixed to the distribution beam (103), and the bottom of the lower guide beam (702) is fixed to the main cross beam (104) by the diagonal brace (703); One end of the lower guide beam (702) in the lower guide mechanism (7) is fixed to the steel pipe pile (102), and the bottom of the lower guide beam (702) is fixed to the steel pipe pile (102) by the diagonal brace (703); S3. High-pressure jet grouting is performed to seal and reinforce the bottom of the sheet pile (8) from top to bottom. S4. Pump water out of the cofferdam and install internal supports layer by layer from top to bottom (9). S5. Excavate the foundation pit to the design elevation, pour the cushion layer and construct the pile cap (10). S6. Backfill sand (11) between the pile cap (10) and the sheet pile (8), and construct the pier body (12) after removing the lowest layer of inner support (9). S7. During the construction of the pier body (12) layer by layer, the inner support (9) is removed layer by layer, and the steel sheet pile (8) is connected to the pier body (12) by installing and converting the inner support (14).

2. The method for constructing a steel sheet pile cofferdam in a rocky area with a thin overburden layer according to claim 1, characterized in that: When the pier body (12) encounters the obstruction of the internal support (9) during construction, multiple embedded parts (13) are pre-embedded on both sides of the lower pier body (12). One end of the internal support (14) is fixed on the embedded part (13), and the other end is fixed on the steel sheet pile (8).

3. The method for constructing a steel sheet pile cofferdam in a rocky area with a thin overburden layer according to claim 2, characterized in that: Multiple anchor bars (1301) in the pre-embedded part (13) are pre-embedded in the pier body (12), and anchor plates (1302) are fixed at the ends of the multiple anchor bars (1301). The anchor plates (1302) are fixedly connected to the conversion inner support (14).

4. The method for constructing a steel sheet pile cofferdam in a rocky area with a thin overburden layer according to claim 3, characterized in that: The anchor plate (1302) is fixedly connected to the anchor bar (1301) by the nut (1304) and the conical sleeve (1303), and the outer side of the anchor plate (1302) is on the same side as the outer side of the pier body (12).

5. The method for constructing a steel sheet pile cofferdam in a rocky area with a thin overburden layer according to claim 3, characterized in that: Multiple stiffening plates (15) are fixed between the periphery of the internal support (14) and the anchor plate (1302).

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