Deep water pebble covering layer buried type lock steel pipe pile cofferdam water stop construction method

Abstract

The application relates to a deep-water pebble covering layer buried type lock steel pipe pile cofferdam water stop construction method, a steel casing is first inserted and driven at a designed insertion and driving position of a steel pipe pile, the steel pipe pile is inserted and driven to a rock layer below a pebble covering layer, a large-diameter steel pipe pile hole is formed, then clay is backfilled in the steel casing, and the steel casing is pulled out; a plurality of slurry outlet holes are formed on a pipe wall of a lower end of the steel pipe pile in advance, the steel pipe pile is inserted into the pile hole, clay in the steel pipe pile is removed, a grouting device is placed in the steel pipe pile, the grouting device forms a closed space in the steel pipe pile, cement slurry is pressed into the steel pipe pile through the grouting device, the cement slurry is pressed into a space between the steel pipe pile and the rock layer through the slurry outlet holes on the steel pipe pile under high pressure, the steel pipe pile is firmly combined with the rock layer, the steel pipe pile can be kept stable under the action of water flow impact, water outside the cofferdam can be prevented from penetrating into the cofferdam from the space between the steel pipe pile and the rock layer, and therefore the water stop effect of the cofferdam is improved.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology and relates to a method for constructing a cofferdam using interlocking steel pipe piles, specifically a method for constructing a deep-water pebble-covered cofferdam with interlocking steel pipe piles for water-stopping. Background Technology

[0002] Cofferdams are commonly used as temporary water-retaining structures in the construction of bridge foundations in underwater areas. Common types of cofferdams include island cofferdams, sheet pile cofferdams, steel pipe pile cofferdams, and single- or double-walled steel cofferdams. Among them, steel pipe pile cofferdams have advantages such as low cost, convenient construction, and recyclability, and are suitable for deep-water construction. Therefore, steel pipe pile cofferdams are often used in deep-water foundation construction. However, steel pipe pile cofferdams are difficult to control for leakage. Therefore, improving the water-stopping effect of steel pipe pile cofferdams is the key to ensuring the smooth progress of construction.

[0003] like Figure 1 , Figure 2 , Figure 3 As shown, a steel pipe pile cofferdam is a closed-loop structure composed of multiple steel pipe piles 1. The lower ends of the steel pipe piles are driven to a certain depth into the rock stratum 3 below the riverbed overburden layer 2. Each steel pipe pile has locking buckles 4 on both sides, and adjacent steel pipe piles 1 are connected by locking buckles 4. The steel pipe piles are usually driven using a vibratory pile hammer. The vibration impact of the lower end of the steel pipe pile on the rock stratum breaks the rock, causing the steel pipe pile to sink. This results in a certain gap between the steel pipe pile and the rock stratum. If water from outside the cofferdam seeps into the gap between the steel pipe pile and the rock stratum, it will further enter the cofferdam from the bottom of the steel pipe pile. In addition, since the locking buckles 4 are rigid structures, if the interlocking locking buckles are not sealed tightly, water from outside the cofferdam will also enter the cofferdam through the gaps in the locking buckles. Therefore, the parts of the steel pipe pile cofferdam that are prone to leakage are mainly the bottom of the steel pipe piles and the locking buckles.

[0004] For leaks in the locking mechanism, filling the locking mechanism with grease, cotton wool, or wooden wedges can achieve a good water-stopping effect. For leaks at the bottom of the steel pipe pile, the usual method is to inject cement grout into the steel pipe pile to seal the bottom. However, due to the low grouting pressure, the cement grout inside the steel pipe pile does not easily diffuse to the outside to seal the gap between the outer wall of the steel pipe pile and the rock stratum. On the one hand, the steel pipe pile is prone to shaking under the impact of water flow, causing the bottom concrete to fail to bond firmly with the rock stratum. On the other hand, water outside the cofferdam can seep into the bottom of the steel pipe pile from the gap between the steel pipe pile and the rock stratum and enter the cofferdam from the bottom. Therefore, the water-stopping effect is not ideal, especially when the riverbed cover is a pebble layer. Due to the high permeability of the pebble layer, a large amount of water will enter the gap between the outer wall of the steel pipe pile and the rock stratum and enter the cofferdam from the bottom of the steel pipe pile, seriously affecting the construction safety inside the cofferdam. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a method for constructing a deep-water pebble-covered, embedded, interlocking steel pipe pile cofferdam for water stopping, thereby improving the water stopping effect of the steel pipe pile cofferdam and ensuring the safety of steel pipe pile cofferdam construction.

[0006] The technical solution of the present invention is as follows:

[0007] A method for constructing a deep-water pebble-covered cofferdam using embedded interlocking steel pipe piles, characterized by the following steps:

[0008] (1) Before each steel pipe pile of the steel pipe pile cofferdam is driven, a steel casing is first driven at the designed driving position of the steel pipe pile. The diameter of the steel casing is larger than the diameter of the steel pipe pile. The lower end of the steel casing is driven to the designed driving depth of the steel pipe pile in the rock layer below the riverbed cover layer. The slag and gravel in the steel casing are cleaned to form a large diameter pile hole. Clay is backfilled in the steel casing to the height of the riverbed cover layer. Then the steel casing is pulled out, and the clay is left in the pile hole.

[0009] (2) A ring-shaped limiting plate is welded circumferentially inside each steel pipe pile. The height of the limiting plate from the lower end of the steel pipe pile is not higher than the height from the bottom of the pile hole to the top of the rock layer. Multiple grout outlet holes are opened on the steel pipe pile wall below the ring-shaped limiting plate.

[0010] (3) Drive the steel pipe pile into the pile hole, with the axis of the steel pipe pile coaxial with the pile hole, remove the clay inside the steel pipe pile, and put a grouting device inside the steel pipe pile.

[0011] The grouting device includes a support frame, a grouting pipe, an annular airbag, and an inflation pipe. The support frame includes an upper support plate and a lower support plate arranged in parallel. The upper and lower support plates are circular plates with a diameter smaller than that of the annular limiting plate inside the steel pipe pile. There is a certain distance between the upper and lower support plates, and a connecting rod is welded between them. The grouting pipe vertically penetrates the upper and lower support plates and is welded to them. The annular airbag is located between the upper and lower support plates, and the axis of the annular airbag coincides with the axis of the upper and lower support plates. An inflation port is provided on the inner side of the annular airbag. When the annular airbag is inflated and not compressed, its thickness is greater than the distance between the upper and lower support plates, and its outer diameter is greater than the inner diameter of the steel pipe pile. The inflation pipe penetrates the upper support plate, and its lower end is fixedly connected to the inflation port on the inner side of the annular airbag.

[0012] The grouting device is placed inside the steel pipe pile with the air bladder not inflated, and the upper support plate is located below the annular limiting plate, with the upper ends of the grouting pipe and the air inflator pipe located outside the upper end of the steel pipe pile.

[0013] (4) Inflate the annular airbag through the inflation tube so that the top and bottom surfaces of the annular airbag press against the upper and lower support plates respectively, and the outer side of the annular airbag presses against the inner wall of the steel pipe pile, forming a closed space between the lower support plate and the bottom of the steel pipe pile. Then, inject cement grout into the closed space of the steel pipe pile through the grouting pipe. The high-pressure cement grout overflows from the bottom of the steel pipe pile and the grout outlet on the steel pipe pile to the outside of the steel pipe pile, squeezing and forcing the clay between the steel pipe pile and the rock layer to rise until the cement grout completely fills the space between the steel pipe pile and the rock layer.

[0014] (5) Inflate the airbag by using the inflation tube to prevent air from entering the airbag, causing the airbag to contract and the grouting device to be removed from the steel pipe pile.

[0015] (6) Following the steps (1) to (5), all steel pipe piles of the steel pipe pile cofferdam are driven into place and connected by locking buckles to complete the installation of the steel pipe pile cofferdam.

[0016] Compared with the ordinary steel pipe pile internal grouting water-stopping method, the present invention has the following advantages:

[0017] (1) The grouting device can form a closed space inside the steel pipe pile. Cement grout is injected into the steel pipe pile through high-pressure grouting and is injected into the outside of the steel pipe pile through the bottom opening and the grout outlet hole on the steel pipe pile. This not only ensures that the bottom opening and side wall of the steel pipe pile are tightly bonded to the rock strata, ensuring that the steel pipe pile resists the impact of water flow and remains stable, but also prevents water outside the cofferdam from seeping into the cofferdam from between the steel pipe pile and the rock strata, thus achieving a good water-stopping effect.

[0018] (2) A steel casing is used to form a large-diameter steel pipe pile hole. The steel pipe pile is inserted into the pile hole by embedding. The distance between the outer wall of the steel pipe pile and the rock layer is large, which can form a thick cement consolidation layer between the steel pipe pile and the rock layer, further increasing the consolidation strength between the steel pipe pile and the rock layer and the stability of the steel pipe pile.

[0019] (3) During grouting, the clay seals between the steel pipe pile and the rock layer, which can prevent grout leakage. The grouting pressure is high, and the grout spreads evenly and densely between the steel pipe pile and the rock layer, which can further improve the water-stopping effect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the plan structure of a steel pipe pile cofferdam;

[0021] Figure 2 This is a schematic diagram of the steel pipe pile interlocking connection structure of a steel pipe pile cofferdam;

[0022] Figure 3 This is a schematic diagram of the elevation structure of a steel pipe pile cofferdam;

[0023] Figure 4 This is a schematic diagram showing the state of the steel pipe pile holes used to form a steel pipe pile cofferdam by driving in steel casings.

[0024] Figure 5 This is a schematic diagram of the state of the steel pipe pile hole after the steel casing has been pulled out.

[0025] Figure 6 This is a schematic diagram of the lower end structure of the steel pipe piles in a steel pipe pile cofferdam.

[0026] Figure 7 This is a schematic diagram showing the state of a steel pipe pile being inserted into a pile hole and a grouting device being installed inside the steel pipe pile.

[0027] Figure 8 This is a schematic diagram of the grouting device when the annular air bladder is not inflated;

[0028] Figure 9 This is a schematic diagram of the grouting device when the annular airbag is inflated;

[0029] Figure 10 This is a schematic diagram of the planar structure of the grouting device when the annular airbag is inflated.

[0030] Figure 11 This is a schematic diagram of the planar structure of one embodiment of the support plate on the grouting device;

[0031] Figure 12 This is a schematic diagram of the planar structure of the annular air bladder of the grouting device;

[0032] Figure 13 This is a schematic diagram showing the state of the grouting device during grouting inside the steel pipe pile. Detailed Implementation

[0033] The specific construction method of this invention is as follows:

[0034] like Figure 4 , Figure 5 As shown, before each steel pipe pile of the steel pipe pile cofferdam is driven, a steel casing 5 is first driven at the designed driving position of the steel pipe pile. The diameter of the steel casing is larger than the diameter of the steel pipe pile. The lower end of the steel casing 5 is driven to the designed driving depth of the steel pipe pile in the rock layer 3 under the riverbed cover layer 2. The slag and gravel inside the steel casing are cleaned to form a large diameter pile hole. Clay 6 is backfilled inside the steel casing to the height of the riverbed cover layer. Then the steel casing is pulled out, and the clay 6 is left in the pile hole.

[0035] like Figure 6 As shown, an annular limiting plate 7 is welded circumferentially inside each steel pipe pile 1. The height of the limiting plate 7 from the lower end of the steel pipe pile 1 is not higher than the height from the bottom of the pile hole to the top of the rock layer. Multiple grout outlet holes 8 are opened on the pipe wall of the steel pipe pile 1 below the annular limiting plate 7.

[0036] like Figure 7 As shown, steel pipe pile 1 is driven into the pile hole, with the axis of the steel pipe pile coaxial with the pile hole. The clay inside the steel pipe pile is removed. A grouting device is placed inside the steel pipe pile.

[0037] like Figures 7 to 12 As shown, the grouting device includes a support frame, a grouting pipe, an annular airbag, and an inflation pipe. The support frame includes an upper support plate 9 and a lower support plate 10 arranged in parallel. The upper and lower support plates are circular plates with a diameter smaller than that of the annular limiting plate 7 inside the steel pipe pile 1. There is a certain distance between the upper and lower support plates, and a connecting rod 11 is welded to them. The grouting pipe 12 vertically penetrates the upper support plate 9 and the lower support plate 10 and is welded to them. The annular airbag 13 is located between the upper support plate 9 and the lower support plate 10. The axis of the annular airbag coincides with the axis of the upper and lower support plates. An inflation port is provided on the inner side of the annular airbag 13. When the annular airbag is inflated and not compressed, its thickness is greater than the distance between the upper and lower support plates, and its outer diameter is greater than the inner diameter of the steel pipe pile. The inflation pipe 14 penetrates the upper support plate 9 and is fixedly connected to the inflation port on the inner side of the annular airbag 13.

[0038] like Figure 7 As shown, the grouting device is placed inside the steel pipe pile 1 with the airbag 13 uninflated, and the upper support plate 9 is located below the annular limiting plate 7, with the upper ends of the grouting pipe 12 and the air inflator 14 located outside the upper port of the steel pipe pile 1.

[0039] like Figure 13 As shown, the annular airbag is inflated through the inflation pipe 14. After the annular airbag 13 expands, its top and bottom surfaces press against the upper support plate 9 and the lower support plate 10 respectively, and its outer surface presses against the inner wall of the steel pipe pile 1, forming a sealed space between the lower support plate and the bottom opening of the steel pipe pile. Then, cement grout 15 is injected into the sealed space of the steel pipe pile through the grouting pipe 12. The high-pressure cement grout 15 overflows from the bottom opening of the steel pipe pile and the grout outlet hole on the steel pipe pile, squeezing and forcing the clay 6 between the steel pipe pile and the rock layer to rise until the cement grout completely fills the space between the steel pipe pile 1 and the rock layer 3. The airbag is then deflated by the inflation pipe, causing the airbag to contract, and the grouting device is removed from the steel pipe pile, completing the installation of one steel pipe pile.

[0040] Following the above method, all steel pipe piles of the steel pipe pile cofferdam are driven into place and connected by locking buckles to complete the installation of the steel pipe pile cofferdam.

[0041] During the above construction process, when grouting is applied into the steel pipe pile, the high-pressure cement grout pushes the grouting device upward. However, due to the friction between the annular airbag 13 and the inner wall of the steel pipe pile 1, and the obstruction of the annular limiting plate 7 on the annular airbag 13, the grouting device is prevented from rising. Therefore, the pressure of the cement grout inside the steel pipe pile 1 increases. When the pressure increases to a certain level, the high-pressure cement grout 15 overflows from the bottom of the steel pipe pile and the grout outlet on the steel pipe pile, squeezing the clay 6 between the steel pipe pile 1 and the rock layer 3, forcing the clay to gradually rise. The cement grout 15 gradually replaces the clay and fills the space between the steel pipe pile and the rock layer. During this process, the clay can prevent the cement grout from leaking from the top of the steel pipe pile, the rock layer, and the overburden layer. After the cement grout solidifies, it will firmly connect the steel pipe pile and the rock layer together.

[0042] To further ensure that the grouting device can withstand the pressure of high-pressure cement grout and not move upward, multiple clips can be installed around the upper support plate. Specifically, the following methods can be used:

[0043] like Figure 11 As shown, at least three slots 91 are equidistantly spaced around the edge of the upper support plate 9 of the grouting device support frame, and an ear plate 16 is welded to both sides of each slot on the top surface of the upper support plate 9; as shown Figure 10 and Figure 8 , Figure 9 As shown, a buckle 17 is installed in each slot, and the upper end of the buckle 17 is rotatably connected to the two ear plates 16 through a pin 18. The lower end of the buckle 17 extends below the upper support plate and tilts outward from the upper support plate. When the annular airbag 13 is not inflated, the lower end of the buckle 17 is located within the outer edge of the upper support plate 9, which facilitates the smooth lowering of the grouting device below the annular limiting plate 7 inside the steel pipe pile. When the annular airbag 13 is inflated, it squeezes the lower end of the buckle 17 to rotate outward from the upper support plate 9. Figure 13 As shown, when the grouting device is grouting, the annular airbag presses the lower end of the buckle 17 against the bottom surface of the annular limiting plate 7. The buckle 17 and the annular limiting plate 7 together prevent the grouting device from moving upward, thereby maintaining the cement grout pressure inside the steel pipe pile.

[0044] Furthermore, such as Figure 8 , Figure 9 As shown, in order to ensure that the buckle can rotate smoothly when it is squeezed, the buckle 17 can be set as S-shaped, with its upper end bent to the inside of the upward support plate and rotatably connected to the two ear plates through a pin, and its lower end bent to the outside of the upward support plate.

[0045] like Figure 8 , Figure 9As shown, to ensure that the buckle 17 can smoothly return to its original position after the annular airbag 13 contracts, facilitating the easy removal of the grouting device from the steel pipe pile, a spring 19 can be connected between the lower end of the buckle 17 and the bottom surface of the upper support plate 9. The spring is arranged along the radial direction of the upper support plate, with one end welded to the lower end of the buckle and the other end welded to the bottom surface of the upper support plate. The spring can be a tension spring. Figure 9 As shown, when the annular airbag 13 inflates, the lower end of the squeeze buckle 17 rotates outward and stretches the spring 19; as Figure 8 As shown, after the annular airbag deflates and contracts, the spring 19 retracts to its natural state and pulls the lower end of the buckle 17 back to within the edge range of the upper support plate 9.

[0046] The cofferdam constructed using the above method injects cement grout between the steel pipe piles and the rock strata, and the distance between the steel pipe piles and the rock strata is relatively large. Therefore, a thick cement consolidation layer is formed between the steel pipe piles and the rock strata, which firmly bonds the steel pipe piles to the rock strata. This ensures that the steel pipe piles will not sway under the impact of water flow, and effectively prevents water from outside the cofferdam from entering the cofferdam from between the steel pipe piles and the rock strata, thereby ensuring the safety of construction inside the cofferdam.

Claims

1. A method for constructing a deep-water pebble-covered cofferdam with embedded interlocking steel pipe piles, characterized in that, Includes the following steps: (1) Before each steel pipe pile of the steel pipe pile cofferdam is driven, a steel casing is driven at the designed driving position of the steel pipe pile. The diameter of the steel casing is larger than the diameter of the steel pipe pile. The lower end of the steel casing is driven to the designed driving depth of the steel pipe pile in the rock layer under the riverbed cover layer. The slag and gravel in the steel casing are cleaned to form a large diameter pile hole. Clay is backfilled in the steel casing to the height of the riverbed cover layer. Then the steel casing is pulled out, and the clay is left in the pile hole. (2) A ring-shaped limiting plate is welded circumferentially inside each steel pipe pile. The height of the limiting plate from the lower end of the steel pipe pile is not higher than the height from the bottom of the pile hole to the top of the rock layer. Multiple grout outlet holes are opened on the steel pipe pile wall below the ring-shaped limiting plate. (3) Drive the steel pipe pile into the pile hole, with the axis of the steel pipe pile coaxial with the pile hole, remove the clay inside the steel pipe pile, and put a grouting device inside the steel pipe pile. The grouting device includes a support frame, a grouting pipe, an annular airbag, and an inflation pipe. The support frame includes an upper support plate and a lower support plate arranged in parallel. The upper and lower support plates are circular plates with a diameter smaller than that of the annular limiting plate inside the steel pipe pile. There is a certain distance between the upper and lower support plates, and a connecting rod is welded between them. The grouting pipe vertically penetrates the upper and lower support plates and is welded to them. The annular airbag is located between the upper and lower support plates, and the axis of the annular airbag coincides with the axis of the upper and lower support plates. An inflation port is provided on the inner side of the annular airbag. When the annular airbag is inflated and not compressed, its thickness is greater than the distance between the upper and lower support plates, and its outer diameter is greater than the inner diameter of the steel pipe pile. The inflation pipe penetrates the upper support plate, and its lower end is fixedly connected to the inflation port on the inner side of the annular airbag. The upper support plate of the grouting device support frame has at least three slots equidistantly spaced around its circumferential edge. An ear plate is welded to both sides of each slot on the top surface of the upper support plate. A buckle is set in each slot. The upper end of the buckle is rotatably connected to the two ear plates by a pin. The lower end of the buckle extends below the upper support plate and tilts outward from the upper support plate. When the annular airbag is not inflated, the lower end of the buckle is located within the outer edge of the upper support plate. When the grouting device is grouting, the annular airbag is inflated and squeezes the lower end of the buckle to rotate outward from the upper support plate, and presses the lower end of the buckle tightly against the bottom surface of the annular limiting plate. The grouting device is placed inside the steel pipe pile with the air bladder not inflated, and the upper support plate is located below the annular limiting plate, with the upper ends of the grouting pipe and the air inflator pipe located outside the upper end of the steel pipe pile. (4) Inflate the annular airbag through the inflation tube so that the top and bottom surfaces of the annular airbag press against the upper support plate and the lower support plate respectively, and the outer side of the annular airbag presses against the inner wall of the steel pipe pile, forming a closed space between the lower support plate and the bottom of the steel pipe pile. Then, inject cement grout into the closed space of the steel pipe pile through the grouting pipe. The high-pressure cement grout overflows from the bottom of the steel pipe pile and the grout outlet hole on the steel pipe pile to the outside of the steel pipe pile, squeezing and forcing the clay between the steel pipe pile and the rock layer to rise until the cement grout completely fills the space between the steel pipe pile and the rock layer. (5) Inflate the airbag by using the inflation tube to prevent air from entering the airbag, causing the airbag to contract and the grouting device to be removed from the steel pipe pile; (6) Following the steps (1) to (5), drive all the steel pipe piles of the steel pipe pile cofferdam into place and connect them with locking buckles to complete the installation of the steel pipe pile cofferdam.

2. The method for constructing a deep-water pebble-covered layer embedded interlocking steel pipe pile cofferdam for water stoppage according to claim 1, characterized in that: The buckle is S-shaped, with its upper end bent inwards towards the upper support plate and rotatably connected to the two ear plates via a pin, and its lower end bent outwards towards the upper support plate.

3. The method for constructing a deep-water pebble-covered layer embedded interlocking steel pipe pile cofferdam for water stoppage according to claim 1 or 2, characterized in that: A spring is connected between the lower end of the buckle and the bottom surface of the upper support plate. The spring is arranged along the radial direction of the upper support plate. One end of the spring is welded to the lower end of the buckle, and the other end is welded to the bottom surface of the upper support plate. The spring is a tension spring. When the annular airbag is inflated, it squeezes the lower end of the buckle to rotate outward and stretches the spring. After the annular airbag is deflated, the spring is in its natural state, and the lower end of the buckle is located within the edge range of the upper support plate.

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