Strip steel casing pile with bag under water environment and construction method thereof

Abstract

The application discloses a kind of water environment under the technology and construction method of adopting bag improvement belt steel casing pile, including steel casing, bag, blade angle protection device, high-pressure grouting hose and the like.The steel casing is the cofferdam of combined pile construction, and is also the carrier of bag lowering.The bag is a circular ring with internal through-penetrating everywhere, and bag body is fixed in the inner wall of steel casing with high-strength binder.The blade angle protection ring is a steel ring with a small angle with steel casing, and is welded in the inner wall of steel casing.The construction method includes welding blade angle protection ring, fixing bag in the inner wall of steel casing with high-strength binder, reliably connecting bag steel grouting port with high-pressure grouting hose, driving into steel casing, drilling hole in steel casing to form pile, grouting into bag, and forming annular reinforcement for pile in water environment.The application is simple in construction, not only improves the problem of poor quality of concrete pouring around pile, but also reliably reinforces the cross-section mutation of pile in water environment.

Description

Technical Field

[0001] This project involves the improvement and reinforcement technology of bored piles in aquatic environments. To be precise, it is the technology and construction method of using a bag to reinforce steel casing piles. Background Technology

[0002] Underwater bored pile construction often requires the segmented driving of steel casings to act as cofferdams. These casings are used for positioning, guiding the borehole, isolating the surface water inside and outside the borehole, or controlling the pile top elevation. After the bored pile construction is completed, the upper part of the steel casing must be partially removed, which is quite difficult. The utilization rate of the lower part of the steel casing, which does not need to be removed, is also low. In addition, in actual construction, due to the difference in hardness between the upper soft soil layer and the lower impermeable soil layer, the borehole diameter in the soft soil layer is slightly larger than that in the impermeable soil layer. When pouring concrete, the underwater concrete is often topped with a layer of soft laitance. As pouring continues and rises to the interface between the soil layers, some of the soft laitance settles at the interface. Continuing to pour cannot effectively replace this laitance, which often causes a sudden change in pile diameter at the interface. Furthermore, due to the influence of the laitance, the quality of the concrete pouring on the outside of the pile cannot be guaranteed. Existing research shows that bored piles formed in aquatic environments exhibit significant stress concentration at the soil layer interface, with a clear pile-soil interaction. This section is the most dangerous section, whether bearing vertical or lateral loads.

[0003] Therefore, it is necessary to design a method that utilizes the retained steel casing to mitigate the adverse effects of abrupt changes in pile diameter at the soil interface and poor quality of concrete pouring around the pile, thereby improving the pile's horizontal bearing capacity and durability. Summary of the Invention

[0004] Technical Problem: The purpose of this invention is to provide a technology and construction method for steel casing piles with a casing in aquatic environments, in order to solve the problems of sudden changes in pile diameter at the soil layer interface of bored cast-in-place piles in aquatic environments and poor concrete pouring quality around the pile body, as described in the background art. This invention strengthens the dangerous sections of the pile body and improves the lateral bearing capacity, safety and durability of the pile.

[0005] Technical Solution: To achieve the above objectives, this invention provides a steel casing pile with a bladder in an aquatic environment, comprising a bored pile, a steel casing, a bladder, a high-pressure grouting hose, a cutting edge protection ring, and a micro earth pressure box. The bladder is located between the bored pile and the steel casing, and multiple bladders are arranged along the direction of the steel casing. The outer side of each bladder is fixed to the inner wall of the steel casing. The upper side of the bladder has a grouting port connected to the high-pressure grouting hose, and the other end of the high-pressure grouting hose extends axially along the top of the steel casing. The cutting edge protection ring is located on the lower side of the bladder and fixed to the inner wall of the steel casing, protecting the bladder from damage during the driving of the steel casing. The micro earth pressure box is located between the inner wall of the steel casing and the bladder.

[0006] The inner diameter of the steel casing is 200mm-400mm larger than the design diameter of the bored pile, and their center lines coincide.

[0007] The bag is a circular bag made of an annular hollow tube, the diameter of which is generally 300-500mm. Its interior is open everywhere, with only one grouting port set in the bag, and the rest are sealed.

[0008] One end of the high-pressure grouting hose is connected to the grouting port, and the other end is sealed with tape to prevent blockage. The hose body is fixed to the inner wall of the steel casing and is injected into the aquatic environment together with the steel casing.

[0009] The high-pressure grouting hose has an inner diameter of 15-25mm, a wall thickness of 3-5mm, and a length that is the actual distance from the designed grouting port to the top of the steel casing; the grouting port is a steel threaded joint grouting port.

[0010] The cutting edge protection ring is a flared steel ring with a slight radial angle to the steel casing. The outer diameter of the ring is the inner diameter of the steel casing, and its thickness is about 3-5 mm. The surface of the cutting edge protection ring has a small round hole for the high-pressure grouting hose to pass through. The diameter of the small round hole is 3 mm-5 mm larger than that of the high-pressure grouting hose.

[0011] The arrangement of the bags along the axial direction of the steel casing is spaced 800mm-1000mm apart, and the arrangement range is from 400mm below the surface of the water environment to the point where the entire body of the bottommost bag is located in the impermeable soil layer.

[0012] The micro earth pressure box is located between the inner wall of the steel casing and the bladder. One micro earth pressure box is set for each bladder, located at the design elevation of the bladder on the inner wall of the steel casing. The quality of grouting into the bladder is qualitatively checked by detecting the active earth pressure, ensuring that the bladder achieves the expected effect after construction.

[0013] The bag is fixed to the inner wall of the steel casing with a high-strength adhesive; the blade protection ring is welded to the inner wall of the steel casing.

[0014] The construction method of steel casing piles with bags in aquatic environments according to the present invention includes:

[0015] Step S1: Construct steel casings in sections, each 2-3m in length. Weld cutting edge protection rings at the designed locations on the inner wall of the steel casing. Use high-strength adhesive to fix the outer periphery of the bag to the inner wall of the steel casing at the designated locations between every two cutting edge protection rings. Then use tape to make the inner periphery of the bag fit tightly against the steel casing to minimize its volume and prevent damage to the bag during the injection process. When grout is injected into the bag later, the injection pressure can break through the tape restriction, allowing the bag to return to a cylindrical shape and achieve the desired effect.

[0016] Step S2: Connect the high-pressure grouting hose to the steel threaded joint grouting port at the top of the bladder. The joint should be pressure-bearing and waterproof. The axis of the high-pressure grouting hose should be parallel to the axis of the steel casing. The high-pressure grouting hose should be bonded to the inner wall of the steel casing. The high-pressure grouting hose should be consistent with the steel casing and connected in sections. Each joint needs to be pressure-bearing and waterproof. During the installation process, holes need to be drilled on the edge protection ring so that the high-pressure grouting hose can fit tightly against the inner wall of the steel casing.

[0017] Step S3: Determine the pile location and lay out the layout, install the cage-type guide frame, and ensure that the axis of the steel casing is vertical during the driving process, with an inclination angle not exceeding 1%. Drive the steel casing in sections to the impermeable soil layer, and make reliable connections between sections and perform pressure-bearing and waterproof treatment until the design elevation is reached. The inner diameter of the precast steel casing is 200mm-400mm larger than the design diameter of the bored pile, and the wall thickness is 15mm-25mm. During construction, ensure that the center line of the steel casing coincides with the center line of the bored pile. The top of the steel casing is designed to be 1-2m above the water surface, so that when the mud pump is placed inside the steel casing for operation, it is not affected by the water environment.

[0018] Step S4: Place the pile driver for drilling, prepare the slurry in a mud pit, circulate and remove slag, clean the hole, hoist the reinforcing cage, install the grouting pipe, pour underwater concrete, and cure. The time from concrete discharge from the mixer to pouring should not exceed 30 minutes. During construction, the grouting pipe should be moved up and down every 30 minutes to prevent the concrete from losing its fluidity and making it difficult to lift the pipe. The pouring elevation should be 0.5 to 1.0m higher than the design elevation of the pile top to remove laitance and eliminate measurement errors. The embedment depth of the grouting pipe depends on the pouring speed and the properties of the concrete, and should generally be controlled within 2 to 4m, but at any time the distance from the top of the poured slurry should not be less than 1m.

[0019] Step S5: Conduct a 7-day compressive strength test. If the strength reaches 75% of the design strength, grouting into the sump is permitted. The grouting process should adhere to the principle of "small flow rate, long duration". After grouting is completed, the high-pressure grouting hose should be permanently sealed. After the grout in the sump solidifies, it forms a ring reinforcement effect on the formed bored pile, which improves the lateral bearing capacity of the pile. This is especially noticeable at the abrupt change in pile cross-section at the junction of soft and hard soil, thus improving the pile's durability and bearing capacity.

[0020] Beneficial effects: Compared with existing processes, the technical advantages of this invention are:

[0021] This invention provides a steel casing pile with a grouted inner wall in aquatic environments and its construction method. By installing a grouted inner wall into the steel casing and grouting, the annular grouted creates confining pressure on the bored pile, forming a hoop effect. The shape of the steel casing further restricts the load on the other side. Therefore, the interaction between the steel casing, the grouted inner wall, the bored pile, and the soil between them effectively improves the poor quality of the concrete pouring around the pile and effectively transfers the load to the grouted inner wall and the steel casing, reducing stress concentration and improving the stress condition of the pile. Furthermore, by fixing the grouted inner wall at the interface between soft and hard soil, the hoop effect provided by the grouted inner wall effectively strengthens the weak interlayer deposited at that location during pouring and, to a certain extent, prevents the diffusion and abnormal sedimentation of the upper weak laitance at the variable cross-section during concrete pouring. Compared to traditional bored piles in aquatic environments, the improved pile provided by this invention has higher lateral bearing capacity, durability, and safety.

[0022] This invention provides a steel casing pile with a sluice bag and its construction method in aquatic environments. The method involves attaching the sluice bag to the inner wall of the steel casing, welding a protective ring to the cutting edge, installing a high-pressure grouting hose, and driving the steel casing in sections for bored pile construction. After completion, grout is injected into the sluice bag through the pre-installed high-pressure grouting hose, creating an interaction between the pile, soil, sluice bag, and steel casing to form a unified whole, improving the horizontal bearing capacity of the pile and the stability of the surrounding soil. For bored piles in untreated aquatic environments, abrupt changes in cross-section and poor quality of the outer perimeter pouring have always been safety hazards for normal use. This invention not only eliminates the hidden danger of abrupt changes in the pile cross-section at the soil interface but also reinforces the surrounding soil, improving the internal integrity of the pile by using the steel casing as a boundary. Attached Figure Description

[0023] Figure 1 This is a structural diagram of the invention after construction is completed.

[0024] Figure 2 This is a top view after the invention has been implemented.

[0025] Figure 3 This is a schematic diagram showing the connection between the bladder and the high-pressure grouting hose of the present invention.

[0026] Figure 4 This is a schematic diagram of the detailed structure of the high-pressure grouting hose of the present invention.

[0027] Figure 5 This is a schematic diagram of the edge protection ring of the present invention.

[0028] Figure 6 This is a schematic diagram of the connection of the miniature earth pressure cell of the present invention.

[0029] The diagram shows: 1. Drilled pile; 2. Steel casing; 3. Grouting bag; 4. High-pressure grouting hose; 5. Cutting edge protection ring; 6. Grouting port; 7. Miniature earth pressure box. Specific implementation methods

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1-5 This invention provides a steel casing pile with a bagged core for use in aquatic environments. The steel casing pile with a bagged core for use in aquatic environments includes a bored pile 1, a steel casing 2, a high-strength polyester fiber bag 3, a high-pressure grouting hose 4, a cutting edge protection ring 5, a steel spiral joint grouting port 6, and a miniature earth pressure box 7. The steel casing bags 3 are fixed to the inside of the steel casing 2 with a high-strength adhesive, spaced 800mm-1000mm apart, starting 400mm below the top surface of the soft soil layer and continuing until the last bag is completely within the impermeable soil layer. The cutting edge protection ring 5 is welded to the inside of the steel casing 2, located between adjacent bags at 800mm-1000mm intervals, to protect the bags 3 during the driving of the steel casing. The high-pressure grouting hose 4 is installed on the inner wall of the steel casing, with one hose per bag. One end of the grouting hose is connected to the steel spiral joint grouting port 6 on the bag, and its top elevation is higher than that of the steel casing 2. The top end is sealed with tape to prevent blockage. After the bag 3 of this invention is implemented, it generates confining pressure on the pile body, acting as a hoop, effectively solving the problem of poor concrete pouring quality around the pile in traditional bored piles. In addition, the pile, bag, steel casing, and the soil in between compress each other, improving the overall integrity of the system. At the same time, by installing the bag 3 at the soil interface, the circumferential pressure provided by the bag 3 can effectively solve the problem of abrupt changes in pile diameter at this point, reinforcing the weak section of the pile body and improving the stress performance of the improved pile.

[0032] The inner diameter of the steel casing 2 is 200-400mm larger than the design diameter of the bored pile 1 to ensure that the drilling rig has a sufficient working platform during the drilling process. The positioning of the steel casing 2 directly affects the positioning of the casing 3, so it is necessary to avoid rubbing against the steel casing 2. The wall thickness of the steel casing 2 is designed to be 15-25mm to ensure that: ① no deformation occurs when the steel casing 2 is driven in; ② the steel casing 2 itself can withstand the water and soil pressure. It should also be noted that the thickness, diameter, and depth of the steel casing are closely related to the specific engineering project and must be tailored to the specific characteristics of the project. The distance between the axis of the steel casing 2 and the axis of the bored pile 1 should not exceed 50mm to ensure positioning and prevent displacement. The top elevation of the steel casing 2 should be 1-2m higher than the water surface. The flood season water level should also be taken into account. The steel casing 2 should be appropriately raised according to the actual project to prevent river water from entering the borehole. The bottom elevation of the steel casing 2 should be driven into a soil layer with high bearing capacity and low permeability to make the structure stable and prevent mud loss.

[0033] The high-strength polyester fiber bag 3 is located on the inner wall of the steel casing 2. Its outer diameter is similar to or slightly larger than the inner diameter of the steel casing 2. It is fixed with a high-strength adhesive and is fixed on its inner wall before the steel casing 2 is driven in. The diameter of the bag is 300 mm, and the spacing between the bags is 800-1000 mm. The number of bags depends on the actual project. Starting from 400 mm below the soft soil layer, the bag body is completely located in the impermeable soil layer until the last bag. After the bags are grouted, they generate ring pressure on the pile body, which effectively improves the stress condition of the pile. In addition, the interaction between the bags and the steel casing improves the integrity of the entire structure.

[0034] In this invention, the larger diameter of the blade edge protection ring 5 is the inner diameter of the steel casing. It is made of steel plate with a thickness of 5-10mm, and its arrangement spacing is the same as that of the bladder 3, but the number is one more than the designed number of bladder 3. It is welded to the inner wall of the steel casing 2. One end of the high-pressure grouting hose 5 is connected to the steel spiral joint grouting port 6, and the hose body is fixed to the inner wall of the steel casing 2. The function of the micro earth pressure box 7 is to qualitatively check the grouting quality of the bladder by detecting the active earth pressure, so as to ensure that the bladder achieves the expected effect after construction.

[0035] The specific implementation steps of this invention are described below:

[0036] Step S1: Weld a cutting edge protection ring to the inner wall of the steel casing, fix the bag to the inner wall of the steel casing with high-strength adhesive, and use tape to make the other side of the bag contact the steel casing to minimize its volume and prevent the bag from being damaged during the injection process.

[0037] Step S2: Connect the high-pressure grouting hose to the grouting port of the steel threaded joint, and weld the high-pressure grouting hose to the inner wall of the steel casing.

[0038] Step S3: Determine the pile position and lay out the layout, install the cage-type guide frame, drive the steel casing in sections to ensure that its axis is vertical and reaches the design elevation.

[0039] Step S4: Place the pile driver to drill, prepare mud in a mud pit, circulate and remove slag, clean the hole, hoist the steel cage, install the guide pipe, pour underwater concrete, and carry out curing.

[0040] Step S5: A 7-day compressive strength test can be conducted. If the strength reaches 75% of the design strength, grouting into the bladder (3) can begin. After the Pearl River is completed, maintenance work should be carried out.

[0041] The working principle of this invention is explained below:

[0042] In this invention, the shape constraints of the steel casing 2 and the bladder 3 allow for interaction between the bored pile 1 and the surrounding soil, effectively improving the quality of concrete pouring around the pile. Simultaneously, when the pile bears lateral loads, part of the load is transferred to the bladder 3, reducing stress concentration and improving the pile's stress distribution. Furthermore, fixing the bladder at the interface between soft and hard soil effectively strengthens the weak interlayer deposited at that location, thus mitigating the diffusion and abnormal sedimentation of the upper weak laitance at the variable cross-section during pouring, avoiding the abrupt changes in cross-section common in traditional bored piles. The expanded bladder strengthens the interaction between the bladder, the bored pile, the steel casing, and the surrounding soil, improving the overall system integrity. This allows the steel casing to also participate in load bearing, significantly reducing the lateral load burden on the pile and avoiding the difficulty of removing the steel casing in traditional processes. Compared to not removing the steel casing, this improved overall integrity fully utilizes its load-bearing capacity, increasing its utilization rate and preventing economic waste.

[0043] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A steel casing pile with a bladder used in aquatic environments, characterized in that: The steel casing pile includes a bored pile (1), a steel casing (2), a grouting bag (3), a high-pressure grouting hose (4), a cutting edge protection ring (5), and a micro earth pressure box (7). The grouting bag (3) is located between the bored pile (1) and the steel casing (2) and is arranged along the axial direction of the steel casing (2). The outer side of each grouting bag (3) is fixed to the inner wall of the steel casing (2). The upper side of the grouting bag (3) is provided with a grouting port (6) connected to the high-pressure grouting hose (4). The other end of the high-pressure grouting hose (4) extends along the axial direction of the steel casing (2) to the top of the steel casing (2). The cutting edge protection ring (5) is located on the lower side of the grouting bag (3) and is fixed to the inner wall of the steel casing (2). It protects the grouting bag from being damaged during the driving of the steel casing (2). The micro earth pressure box (7) is located between the inner wall of the steel casing (2) and the grouting bag (3).

2. The steel casing pile with a bladder in an aquatic environment as described in claim 1, characterized in that: The inner diameter of the steel casing (2) is 200mm-400mm larger than the design diameter of the bored pile (1), and their center lines coincide.

3. The steel casing pile with a bladder in an aquatic environment as described in claim 1, characterized in that: The bag (3) is a round bag made of a ring-shaped hollow tube with a diameter of 300-500mm. Its interior is open everywhere, with only one grouting port (6) set in the bag (3), and the rest are closed.

4. The steel casing pile with a bladder in an aquatic environment as described in claim 1, characterized in that: One end of the high-pressure grouting hose (4) is connected to the grouting port (6), and the other end is sealed with tape to prevent blockage. The hose body of the high-pressure grouting hose (4) is fixed to the inner wall of the steel casing (2) and is driven into the soil in the water environment together with the steel casing (2).

5. The steel casing pile with a bladder in an aquatic environment as described in claim 4, characterized in that: The inner diameter of the high-pressure grouting hose (4) is 15-25mm, the wall thickness is 3-5mm, and the length is the actual distance from the designed grouting port to the top of the steel casing (2); the grouting port (6) is a steel threaded joint grouting port.

6. The steel casing pile with a bladder in an aquatic environment as described in claim 1, characterized in that: The cutting edge protection ring (5) is a horn-shaped steel ring with a small radial angle to the steel casing. Its outer diameter is the same as the inner diameter of the steel casing (2), and its thickness is 3-5mm. The cutting edge protection ring (5) has a small round hole on its surface for the high-pressure grouting hose (4) to pass through. The diameter of the small round hole is 3mm-5mm larger than the diameter of the high-pressure grouting hose (4).

7. The steel casing pile with a bladder in an aquatic environment as described in claim 1, characterized in that: The arrangement of the bags (3) along the axial direction of the steel casing (2) is spaced at intervals of 800mm-1000mm, and the arrangement range is from 400mm below the surface of the water environment to the point where the body of the bottom bag (3) is entirely located in the impermeable soil layer.

8. The steel casing pile with a bladder in an aquatic environment according to claim 1, characterized in that: The micro earth pressure box (7) is located between the inner wall of the steel casing (2) and the bladder (3). For each bladder (3), one micro earth pressure box (7) is set up at the design elevation of the bladder (3) on the inner wall of the steel casing (2). The grouting quality of the bladder (3) is qualitatively checked by detecting the pressure, so as to ensure that the bladder (3) achieves the expected effect after the construction is completed.

9. The steel casing pile with a bladder in an aquatic environment according to claim 1, characterized in that: The bag (3) is fixed to the inner wall of the steel casing (2) with a high-strength adhesive; the blade protection ring (5) is welded to the inner wall of the steel casing (2).

10. A construction method for steel casing piles using a bagged casing in an aquatic environment as described in claim 1, characterized in that: This construction method includes: Step S1: Make steel casing (2) in sections, each section is 2-3m long. Weld the cutting edge protection ring (5) at the designed position on the inner wall of the steel casing (2). Use high-strength adhesive to fix the outer periphery of the bag (3) to the inner wall of the steel casing (2) at the designated position between every two cutting edge protection rings (5). Then use tape to make the inner periphery of the bag (3) close to the steel casing (2) to minimize its volume and prevent damage to the bag (3) during the injection process. When grout is injected into the bag (3) later, the grouting pressure can break through the tape restriction and make the bag (3) return to the round tube shape so as to give full play to the use effect of the bag (3). Step S2: Connect the high-pressure grouting hose (4) to the steel threaded joint grouting port (6) at the top of the bag (3). Make pressure-bearing and waterproof treatment at the joint. The axis of the high-pressure grouting hose (4) is parallel to the axis of the steel casing (2). Bond the high-pressure grouting hose (4) to the inner wall of the steel casing (2). The high-pressure grouting hose (4) should be consistent with the steel casing (2). Connect in sections. Each joint needs to be made pressure-bearing and waterproof. During the installation process, a hole needs to be made on the blade protection ring (5) so that the high-pressure grouting hose (4) can fit tightly against the inner wall of the steel casing (2). Step S3: Determine the pile position and lay out the layout, install the cage-type guide frame, and ensure that the axis of the steel casing (2) is vertical and the tilt angle does not exceed 1% during the process of driving in the steel casing (2). Drive the steel casing (2) into the impermeable soil layer in sections, make reliable connections between sections, and perform pressure-bearing and waterproof treatment to reach the design elevation. The inner diameter of the precast steel casing (2) is 200mm-400mm larger than the design diameter of the bored pile (1), and the wall thickness is 15mm-25mm. During the construction process, ensure that the center line of the steel casing (2) coincides with the center line of the bored pile (1). The top design elevation of the steel casing (2) is 1-2m higher than the water surface. When the mud pump is placed inside the steel casing (2) for operation, it is not affected by the water environment. Step S4: Place the pile driver for drilling, prepare the slurry in a mud pit, circulate and remove slag, clean the hole, hoist the reinforcing cage, install the grouting pipe, pour underwater concrete, and cure. The time from concrete discharge from the mixer to pouring should not exceed 30 minutes. During construction, the grouting pipe should be moved up and down every 30 minutes to prevent the concrete from losing its fluidity and making it difficult to lift the pipe. The pouring elevation should be 0.5 to 1.0m higher than the design elevation of the pile top to remove laitance and eliminate measurement errors. The embedment depth of the grouting pipe depends on the pouring speed and the properties of the concrete, and should be controlled within 2 to 4m, but at any time the distance from the top of the poured slurry should not be less than 1m. Step S5: Use 7-day compressive strength test. If it reaches 75% of the design strength, grouting into the bag (3) is allowed. The grouting process should adhere to the principle of "small flow rate, long time". After the grouting is completed, the high-pressure grouting hose is permanently sealed. After the grout in the bag (3) solidifies, it forms a hoop effect on the formed bored pile, which improves the lateral bearing capacity of the pile. It can be significantly improved, especially at the junction of soft and hard soil where the pile cross section changes abruptly, thus improving the durability and bearing capacity of the pile.

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