A diameter-expanded anti-seismic casing concrete pile in a seasonal frozen soil area and a construction method thereof

Abstract

The application discloses a kind of season frozen soil area's expansion anti-seismic casing concrete pile and construction method, plastic casing top is equipped with the top cover of grouting port and drainage port, bottom is equipped with prefabricated pile tip;The top and bottom of the expansion rubber are fixed to the outside of plastic casing by fixed hoop sealingly;Several grouting ports are evenly distributed on the plastic casing in the range of expansion rubber;Several drainage plates are provided with heating plates, and are arranged symmetrically outside the expansion rubber;The embedded pipe is arranged in the inner wall of plastic casing and prefabricated pile tip, and the entrance of drag reduction material at the plastic casing and the exit of drag reduction material at the bottom of prefabricated pile tip are arranged.The application effectively improves the setting efficiency by setting soil-breaking cone tip at the end of prefabricated pile and injecting drag reduction material under pressure.The expansion rubber increases the side friction resistance of casing concrete pile, eliminates the adverse effects of concrete curing shrinkage, and improves the bearing capacity;Meanwhile, the heating plate is used to avoid frost heaving disaster.

Description

Technical Field

[0001] This invention relates to the field of engineering foundation technology, and in particular to an enlarged diameter seismic-resistant sleeve concrete pile and its construction method in seasonally frozen soil areas. Background Technology

[0002] With the continuous advancement of engineering construction in my country, various new composite foundation technologies have emerged. Concrete casing pile technology, as a novel foundation treatment technology for embankment engineering, has also developed rapidly, but due to its construction characteristics, it still has some engineering defects.

[0003] Concrete casing piles are installed by driving a precast cone tip into the soil using a pile driver. The requirement that the pile diameter be smaller than the precast tip inevitably leads to a gap between the pile and the soil after construction. The pile's frictional resistance (bearing capacity) only develops after the soil slowly deforms and fills the void, meaning the bearing capacity of the finished concrete casing pile does not meet design requirements. Furthermore, the shrinkage during concrete curing causes the concrete to separate from the casing, which also negatively impacts the pile's bearing capacity. Concrete casing piles are often used in water-rich soft soil layers, where the installation generates excess pore water pressure that dissipates slowly, resulting in a long recovery time for the surrounding soil after damage.

[0004] Furthermore, water in seasonally frozen soil layers will freeze into ice crystals in sub-zero temperatures, causing frost heave in the soil and adversely affecting its structure. Concrete casing piles located in seasonally frozen soil layers may deform due to the frost heave of the surrounding soil, leading to pile cracks or even breakage, seriously jeopardizing project safety.

[0005] Therefore, in order to solve the engineering defects of casing concrete piles due to their construction characteristics, ensure the safety and durability of casing concrete piles in seasonally frozen soil strata, and meet the seismic requirements of engineering projects, there is an urgent need for a new type of casing concrete pile that can quickly reach the design bearing capacity in seasonally frozen soil areas. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides an enlarged-diameter seismic-resistant sleeve concrete pile and its construction method for seasonally frozen soil regions. The technical solution adopted by this invention to solve its technical problem is as follows:

[0007] An enlarged diameter seismic-resistant casing concrete pile for seasonally frozen soil regions includes a plastic casing and its auxiliary components, a top cover, a precast pile tip, pile body concrete, and a precast pile head.

[0008] The plastic sleeve is fitted with a top cover and a precast pile tip at the bottom; the pile body concrete is cast in place under pressure by installing the top cover on the top of the plastic sleeve; the precast pile head is installed on top of the pile body concrete.

[0009] The top cover is provided with a grouting port and a drain port, and is equipped with a pressure gauge;

[0010] The auxiliary components of the plastic sleeve include an expanded diameter rubber, a fixing clamp, a drainage board, a heating plate, and a pre-embedded pipe;

[0011] The top and bottom of the expanded diameter rubber are sealed and fixed to the outside of the plastic sleeve by a fixing hoop; several slurry outlets are evenly distributed on the plastic sleeve within the range of the expanded diameter rubber; several drainage boards are symmetrically arranged circumferentially on the outside of the expanded diameter rubber; the heating plate is located inside the drainage board; the pre-embedded pipe is set in the inner wall of the plastic sleeve and inside the precast pile tip; the top of the pre-embedded pipe is provided with a drag-reducing material inlet and the bottom is provided with a drag-reducing material outlet; the drag-reducing material inlet passes through the plastic sleeve above the fixing hoop and is sealed and connected to the plastic sleeve; the drag-reducing material outlet is located at the soil-breaking cone tip at the bottom of the precast pile tip.

[0012] Furthermore, the maximum outer diameter of the precast pile tip is greater than the outer diameter of the plastic sleeve.

[0013] Furthermore, the precast pile head is installed on top of the pile body concrete after the top cover is removed;

[0014] Furthermore, the heating plate is installed in a drainage board within the seasonally frozen soil layer and has a waterproof function; the heating plate is equipped with a temperature sensing element, and solar energy is preferred, with its power required to ensure that the seasonally frozen soil layer around the casing concrete pile does not freeze and thaw.

[0015] Furthermore, the location of the slurry outlet on the plastic sleeve does not coincide with the location of the drainage board; the plastic sleeve meets the airtightness requirements after being connected to the top cover.

[0016] On the other hand, this invention provides a construction method for enlarged diameter seismic-resistant sleeve concrete piles in seasonally frozen soil areas, the method comprising the following steps:

[0017] S1. After fixing the plastic sleeve to the precast pile tip, hoist it to the designated area;

[0018] S2. The plastic sleeve and its auxiliary components are pulled into the steel pipe by the pile driver. The bottom of the steel pipe is pressed against the precast pile tip. After the precast pile tip is pressed into the soil, the drag reduction material is pressurized and injected into the drag reduction material inlet. It is then driven through the pre-embedded pipe and the drag reduction material outlet. The drag reduction is carried out by static pressure or vibration of the pile driver.

[0019] S3. After driving to the design elevation, fill the plastic sleeve with water and at the same time use the traction cable to pull out the steel sink pipe while continuing to fill with water until the water level is level with the top surface of the plastic sleeve.

[0020] S4. Seal the top cover onto the plastic sleeve, and open the grouting port and drain port. Inject concrete into the plastic sleeve through the grouting port, and the concrete enters the expansion rubber through the grout outlet. Drain the water from the plastic sleeve and expansion rubber through the drain port. After the water is drained, close the drain port and continue to pressurize and inject concrete into the plastic sleeve through the grouting port, so that the expansion rubber expands to the design requirements. Close the grouting port and stop injecting concrete.

[0021] S5. After the concrete of the pile body has initially set, remove the top cover and install the precast pile head; connect the drainage board to the drainage system; connect the heating plate to the power supply.

[0022] S6. Repeat the above steps until all the casing concrete piles are installed.

[0023] Furthermore, in S1, after the plastic sleeve is fixedly connected to the precast pile tip, the pre-embedded pipe should be kept unobstructed.

[0024] Furthermore, in S2, the drag-reducing material is high-pressure water or high-pressure gas; the injection pressure of the drag-reducing material is designed, calculated, and adjusted in real time according to the driving depth; during the drag-reducing driving process, the verticality and speed of the plastic sleeve driving are controlled.

[0025] Furthermore, in S4, the expansion of the rubber diameter to the design requirements is specifically achieved through a construction method that controls the concrete injection pressure and the concrete pouring volume.

[0026] Furthermore, the drainage board maintains autonomous drainage operation during the construction and long-term operation of the casing concrete piles; in the event of an earthquake, the drainage board is connected to a water pump to promptly discharge excess pore water in the soil caused by the earthquake, preventing soil liquefaction damage; the water discharged by the drainage board enters the drainage system, avoiding random drainage within the site.

[0027] When the temperature of the seasonally frozen soil layer where the heating plate is located is lower than a certain degree, the power supply is turned on to carry out heating operations, so that the temperature of the seasonally frozen soil layer is higher than a certain degree, ensuring that the seasonally frozen soil layer does not freeze and thaw.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention employs drag-reducing driving technology, specifically by setting a ground-breaking cone at the tip of the precast pile and injecting drag-reducing material under pressure. This achieves drag-reducing driving effects for the precast pile tip, plastic sleeve, and their auxiliary components, effectively improving driving efficiency.

[0030] In this invention, the preferred drag-reducing material is high-pressure water or high-pressure gas. High-pressure water or high-pressure gas assists the soil-breaking cone tip in breaking the soil. At the same time, it can effectively reduce the frictional resistance between the precast pile tip and the soil layer, and improve the driving efficiency of the precast pile tip. The high-pressure water can be discharged through the drainage board, and the high-pressure gas can be discharged directly through the soil without polluting the soil around the pile. This ensures that the drag-reducing driving of the casing concrete pile is efficient, energy-saving, and environmentally friendly.

[0031] In this invention, the diameter-expanding rubber can enlarge the diameter of the casing concrete pile by pressurizing and injecting concrete after the casing concrete pile is driven. Combined with the drainage board, it can promptly reduce the excess pore water pressure in the soil surrounding the casing concrete pile, ensuring a tight bond between the casing concrete pile and the surrounding soil, and increasing the side friction resistance of the casing concrete pile. In addition, the diameter-expanding rubber can eliminate the adverse effects of concrete curing shrinkage, allowing the pile concrete to fully contact the casing, effectively improving the bearing capacity of the casing concrete pile and overcoming the defect of insufficient early bearing capacity of traditional casing concrete piles. Furthermore, through the drainage board, the excess pore water pressure in the soil layer can be promptly reduced, which can greatly improve the shear strength of the soil and effectively improve the bearing capacity of the casing concrete pile composite foundation.

[0032] In this invention, the expanding rubber is fixed to the outside of the plastic sleeve by a fixing hoop and a drainage plate, which is simple in structure and easy to promote in engineering. At the same time, the expanding rubber is pressurized through the slurry outlets evenly distributed on the plastic sleeve to achieve concrete pouring, which makes construction fast, convenient and efficient.

[0033] The drainage board in this invention can meet the drainage needs during the construction of the casing concrete pile, promptly drain excess pore water and high-pressure water drag-reducing materials from the soil around the casing concrete pile, reduce the disturbance of the soil around the pile during construction, and improve the bearing capacity of the casing concrete pile and the surrounding soil. At the same time, during the long-term operation phase, it ensures that excess water pressure generated under operating loads and seismic loads can be drained in a timely manner, preventing liquefaction damage to the soil around the casing concrete pile and improving the seismic resistance of the casing concrete pile.

[0034] In this invention, the heating plate can directly prevent groundwater in the seasonally frozen soil layer around the casing concrete pile from freezing into ice crystals under the sub-zero winter conditions, thus avoiding the adverse effects of soil frost heave damage on the casing concrete pile and its superstructure. The drainage plate allows the groundwater around the casing concrete pile to flow and exchange, which can assist the heating plate in preventing the groundwater in the soil layer within a certain range around the casing concrete pile from freezing, effectively preventing frost heave disasters in the casing concrete pile and its surrounding soil. Attached Figure Description

[0035] Figure 1 This is a side cross-sectional view of a double-casing concrete pile;

[0036] Figure 2 yes Figure 1AA section;

[0037] Figure 3 It is a side cross-sectional view of the concrete grouting of the double-casing concrete pile;

[0038] Figure 4 yes Figure 3 BB cross section.

[0039] In the figure, 1 is a plastic sleeve; 1-1 is a grout outlet; 2 is an expanded diameter rubber; 3 is a fixing hoop; 4 is a drainage board; 5 is an electric heating element; 6 is an embedded pipe; 6-1 is a drag-reducing material outlet; 7 is a top cover; 7-1 is a grouting port; 7-2 is a drainage port; 7-3 is a pressure gauge; 8 is a precast pile tip; 8-1 is a soil-breaking cone tip; 9 is pile body concrete; and 10 is a precast pile head. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figures 1-2 As shown, an enlarged-diameter seismic-resistant sleeve concrete pile for seasonally frozen soil regions includes a plastic sleeve 1 and its auxiliary components, a precast pile tip 8, pile body concrete 9, and a precast pile head 10. The maximum outer diameter of the precast pile tip is larger than the outer diameter of the plastic sleeve.

[0042] The auxiliary components of the plastic sleeve 1 include an expanded diameter rubber 2, a fixing clamp 3, a drainage board 4, a heating plate 5, and a pre-embedded pipe 6;

[0043] The top and bottom of the expanded diameter rubber 2 are sealed and fixed to the outside of the plastic sleeve 1 by fixing clamps 3; several slurry outlets 1-1 are evenly distributed on the plastic sleeve 1 within the range of the expanded diameter rubber 2; several drainage boards 4 are symmetrically arranged circumferentially on the outside of the expanded diameter rubber 2; the heating plate 5 is located inside the drainage board 4; the pre-embedded pipe 6 is set in the inner wall of the plastic sleeve 1 and inside the precast pile tip 8, for transmitting drag-reducing materials; the heating plate 5 is set within the seasonally frozen soil layer and has a waterproof function; the heating plate 5 is equipped with a temperature sensing element, and solar energy is preferred, and its power should be The system is designed to prevent the seasonally frozen soil layer around the casing concrete pile from freezing and thawing. The pre-embedded pipe 6 has a drag-reducing material inlet 6-1 at the top and a drag-reducing material outlet 6-2 at the bottom. The drag-reducing material inlet 6-1 extends from the top of the plastic casing 1 and is sealed to it. The drag-reducing material outlet 6-2 is located at the breaking cone tip 8-1 at the bottom of the precast pile tip 8. The drag-reducing material is determined based on the site conditions. If the groundwater level is low or there are obstacles such as gravel or pebbles, high-pressure water is preferred. If the groundwater level is high, high-pressure air is preferred. (Thixotropic mud is not recommended as it will affect the pile-soil contact, reduce the bearing capacity of the casing concrete pile, and clog the drainage pipe.)

[0044] The number of drainage boards 4 is determined according to the construction drainage and seismic drainage design requirements of the casing concrete pile, and should be no less than four sets; the opening position of the grout outlet on the plastic casing does not coincide with the position of the drainage board.

[0045] The setting of the slurry outlet 1-1 should meet the requirements of concrete pouring inside the expanded diameter rubber 2, so that the concrete inside the expanded diameter rubber 2 can be completely filled; the setting of the size of the expanded diameter rubber 2 should meet the design requirements of the expanded diameter of the casing concrete pile, and after the expanded diameter, it can be tightly connected with the expanded diameter of the casing concrete pile.

[0046] The pile body concrete 9 is formed by pressure casting with a top cover 7 installed on the top of the plastic sleeve 1; the precast pile head 10 is located on top of the pile body concrete 9; the top cover 7 consists of a grouting port 7-1, a drainage port 7-2, and a pressure gauge 7-3.

[0047] Furthermore, the plastic sleeve 1 should meet the airtightness requirements after being connected to the top cover 7; the dimensions of the precast pile tip 8 should meet the installation requirements of the plastic sleeve 1.

[0048] This invention also provides a construction method for enlarged diameter seismic-resistant sleeve concrete piles in seasonally frozen soil areas, the method comprising the following steps:

[0049] (1) After the plastic sleeve 1 is fixedly connected to the precast pile tip 8, it is hoisted to the designated area; after the plastic sleeve 1 is fixedly connected to the precast pile tip 8, the embedded pipe 6 is kept unobstructed.

[0050] (2) The plastic sleeve 1 and its auxiliary components are pulled into the steel pipe by the pile driver. The bottom of the steel pipe is pressed against the precast pile tip 8. After the precast pile tip 8 is pressed into the soil, the drag-reducing material is injected into the precast pile tip 8 after passing through the drag-reducing material inlet 6-1, the pre-embedded pipe 6, and the drag-reducing material outlet 6-2. The drag-reducing material is then injected into the precast pile tip 8 under pressure. The pile driver performs drag reduction by static pressure or vibration. The strength of the precast pile tip 8 and the soil-breaking cone tip 8-1 should meet the requirements for driving the sleeve concrete piles at the project site. The drag-reducing material is preferably high-pressure water or high-pressure gas. The injection pressure p of the drag-reducing material is adjusted in real time according to the driving depth and is determined by design calculation. p>ητ, where τ represents the shear strength of the soil and η is a safety factor greater than 1, which is 1.1 or 1.2 and is determined by the soil properties.

[0051] The shear strength of soil is calculated using the formula τ = c + σtanφ, where c represents the soil cohesion, σ represents the soil normal stress, and φ represents the soil internal friction angle. c, σ, and φ are all related to the soil depth. c and φ are determined through exploration, while σ can be determined through a combination of exploration and calculation. σ = ∑γ i h i In the formula, γ i Indicates the unit weight of each soil layer, γ i Indicates the thickness of each soil layer;

[0052] During the drag-reducing driving process of the pile driver, the verticality and speed of driving the plastic sleeve 1 should be controlled.

[0053] (3) After driving to the design elevation, water is injected into the plastic sleeve 1, and at the same time, the steel sinker is pulled out by the traction cable. Water is injected while pulling out until the water level is level with the top surface of the plastic sleeve 1.

[0054] (4) Seal the top cover 7 onto the plastic sleeve 1, open the grouting port 7-1 and the drain port 7-2; inject concrete into the plastic sleeve 1 and the expanded diameter rubber 2 through the grouting port 7-1, and drain the water from the plastic sleeve 1 and the expanded diameter rubber 2 through the drain port 7-2; after the water is drained, close the drain port 7-2, and continue to pressurize and inject concrete into the plastic sleeve 1 and the expanded diameter rubber 2 through the grouting port 7-1, so that the expanded diameter rubber 2 expands to the design requirements; close the grouting port 7-1 and stop injecting concrete; the expansion of the expanded diameter rubber 2 to the design requirements is specifically achieved by controlling the concrete injection pressure and the concrete pouring volume.

[0055] (5) Figures 3-4 As shown, after the pile body concrete 9 has initially set, remove the top cover 7 and install the precast pile head 10; connect the drainage board 4 to the drainage system; and connect the heating plate 5 to the power supply.

[0056] (6) Repeat the above steps until all the casing concrete piles are installed.

[0057] Furthermore, the drainage board 4 maintains autonomous drainage operation during the construction and long-term operation of the casing concrete pile; in the event of an earthquake, the drainage board 4 is connected to a water pump to promptly discharge excess pore water in the soil caused by the earthquake, preventing soil liquefaction damage; the water discharged by the drainage board 4 enters the drainage system, avoiding random drainage within the site.

[0058] When the temperature of the seasonally frozen soil layer where the heating plate 5 is located is below 0 degrees, the power supply is turned on to carry out heating operations, so that the temperature of the seasonally frozen soil layer is above 0 degrees, ensuring that the seasonally frozen soil layer does not freeze and thaw.

[0059] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A type of enlarged-diameter seismic-resistant sleeve concrete pile for seasonally frozen soil regions, characterized in that... This includes plastic sleeves and their accessories, top cover, precast pile tip, pile body concrete, and precast pile head; The plastic sleeve is fitted with a top cover and a precast pile tip at the bottom; the pile body concrete is cast in place under pressure by installing the top cover on the top of the plastic sleeve; the precast pile head is installed on top of the pile body concrete. The top cover is provided with a grouting port and a drain port, and is equipped with a pressure gauge; The auxiliary components of the plastic sleeve include an expanded diameter rubber, a fixing clamp, a drainage board, a heating plate, and a pre-embedded pipe; The top and bottom of the expanded diameter rubber are sealed and fixed to the outside of the plastic sleeve by fixing hoops; several slurry outlets are evenly distributed on the plastic sleeve within the range of the expanded diameter rubber; several drainage boards are symmetrically arranged circumferentially on the outside of the expanded diameter rubber; the heating plate is located inside the drainage board; the heating plate is installed in the drainage board within the range of the seasonally frozen soil layer and has a waterproof function to ensure that the seasonally frozen soil layer does not freeze and thaw; the pre-embedded pipe is set in the inner wall of the plastic sleeve and inside the precast pile tip; the pre-embedded pipe is provided with a drag-reducing material inlet at the top and a drag-reducing material outlet at the bottom, and the drag-reducing material is high-pressure water or high-pressure gas; the drag-reducing material inlet passes through the plastic sleeve above the fixing hoop and is sealed and connected to the plastic sleeve; the drag-reducing material outlet is located at the soil-breaking cone tip at the bottom of the precast pile tip.

2. The expanded diameter seismic-resistant casing concrete pile for seasonally frozen soil regions according to claim 1, characterized in that, The maximum outer diameter of the precast pile tip is greater than the outer diameter of the plastic sleeve.

3. The expanded diameter seismic-resistant casing concrete pile for seasonally frozen soil regions according to claim 1, characterized in that, The precast pile head is installed on top of the pile body concrete after the top cover is removed.

4. The expanded diameter seismic-resistant casing concrete pile for seasonally frozen soil regions according to claim 1, characterized in that, The location of the slurry outlet on the plastic sleeve does not coincide with the location of the drainage board; the plastic sleeve meets the airtightness requirements after being connected to the top cover.

5. A construction method using an enlarged-diameter seismic-resistant casing concrete pile in a seasonally frozen soil region as described in any one of claims 1-4, characterized in that, The method includes the following steps: S1. After fixing the plastic sleeve to the precast pile tip, hoist it to the designated area; S2. The plastic sleeve and its auxiliary components are pulled into the steel pipe by the pile driver. The bottom of the steel pipe is pressed against the precast pile tip. After the precast pile tip is pressed into the soil, the drag reduction material is pressurized and injected into the drag reduction material inlet. It is then driven through the pre-embedded pipe and the drag reduction material outlet. The drag reduction is carried out by static pressure or vibration of the pile driver. S3. After driving to the design elevation, fill the plastic sleeve with water and at the same time use the traction cable to pull out the steel sink pipe while continuing to fill with water until the water level is level with the top surface of the plastic sleeve. S4. Seal the top cover onto the plastic sleeve, and open the grouting port and drain port. Inject concrete into the plastic sleeve through the grouting port, and the concrete enters the expansion rubber through the grout outlet. Drain the water from the plastic sleeve and expansion rubber through the drain port. After the water is drained, close the drain port and continue to pressurize and inject concrete into the plastic sleeve through the grouting port, so that the expansion rubber expands to the design requirements. Close the grouting port and stop injecting concrete. S5. After the concrete of the pile body has initially set, remove the top cover and install the precast pile head; connect the drainage board to the drainage system; connect the heating plate to the power supply. S6. Repeat the above steps until all the casing concrete piles are installed.

6. The construction method according to claim 5, characterized in that, In S1, after the plastic sleeve is fixedly connected to the precast pile tip, the pre-embedded pipe should be kept unobstructed.

7. The construction method according to claim 5, characterized in that, In step S2, the drag-reducing material is high-pressure water or high-pressure gas; the injection pressure of the drag-reducing material is designed, calculated and adjusted in real time according to the driving depth; during the drag-reducing driving process, the verticality and speed of the plastic sleeve driving are controlled.

8. The construction method according to claim 5, characterized in that, In S4, the expansion of the rubber diameter to the design requirements is achieved through a construction method that controls the concrete injection pressure and the concrete pouring volume.

9. The construction method according to claim 5, characterized in that, The drainage system is used in the event of an earthquake. It connects the drainage board to the water pump and drainage system to drain excess pore water in the soil caused by the earthquake, thus preventing soil liquefaction damage. All water discharged by the drainage board enters the drainage system, avoiding random drainage within the site.

Images