A steel pipe screw pile and a method for determining its bearing capacity

Abstract

This invention provides a steel pipe helical pile and a method for determining its bearing capacity. The steel pipe helical pile includes: a pile body; multiple helical pile blades arranged axially around the pile body; and multiple overlapping blades arranged radially around the helical pile blades. The overlapping blades contract when the pile body is screwed into the soil in the forward direction, the pile body reverses direction after reaching a set depth, and the overlapping blades open and embed themselves into the foundation soil when the pile body reverses direction. The tensile and compressive bearing capacities of the steel pipe helical pile are determined based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile after the overlapping blades are unfolded, and the vertical shear force of the soil around the pile. This invention can form a more effective interlocking and embedding effect with the foundation soil, utilizing the bearing potential of the undisturbed soil, and significantly improving the compressive and tensile bearing capacities of the steel pipe helical pile without significantly increasing material consumption.

Description

Technical Field

[0001] This invention relates to the field of steel pipe helical pile technology, and in particular to a steel pipe helical pile and a method for determining its bearing capacity. Background Technology

[0002] Steel pipe helical piles are a type of foundation engineering material that combines a steel pipe with helical pile blades. They are mainly used for foundation reinforcement, load transfer, and structural support. Their core feature lies in the combined action of the helical pile blades and the steel pipe, which, by being screwed into the soil, form a stable soil-pile composite, thereby improving bearing capacity and pull-out resistance.

[0003] Currently, when dealing with soft soil foundations, the compressive and tensile bearing capacities of steel pipe helical piles need to be improved. This is usually done by increasing the number of helical pile blades or increasing the area, which consumes a lot of materials and also increases the difficulty of screwing the steel pipe helical piles into the soil and the construction difficulty. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a steel pipe helical pile and a method for determining its bearing capacity, which can form a more effective interlocking and embedding effect with the foundation soil, and utilize the bearing potential of the original soil to significantly improve the compressive bearing capacity and tensile bearing capacity of the steel pipe helical pile without significantly increasing material consumption.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a steel pipe helical pile, comprising:

[0006] pile body;

[0007] Multiple helical pile blades are arranged around the pile body along its axial direction;

[0008] Multiple stacked blades are arranged radially along the helical pile blades;

[0009] The superimposed blades retract when the pile body is screwed into the soil in the forward direction, the pile body begins to reverse after screwing into a set depth, and the superimposed blades open and embed into the foundation soil when the pile body reverses; the tensile bearing capacity and compressive bearing capacity of the steel pipe helical pile are determined based on the parameter data of the steel pipe helical pile, the horizontal soil pressure around the pile after the superimposed blades are unfolded, and the vertical shear force of the soil around the pile.

[0010] Optionally, the pile body includes:

[0011] A steel pipe, with multiple helical pile blades arranged circumferentially along the steel pipe axis;

[0012] A tapered head installed at the end of a steel pipe.

[0013] Optionally, the helical pile blade includes:

[0014] The annular blade is fixed to the steel pipe at a set inclination and cuts into the soil at an angle downwards when the steel pipe is screwed into the soil in the forward direction.

[0015] Multiple hinged fasteners are provided on the annular blades, and the hinged fasteners are rotatably connected to the superimposed blades.

[0016] Optionally, the stacked blades include:

[0017] The upper and lower blades are rotatably connected to the hinged fixing member. When the blades are contracted, the parts other than the blade tail overlap with the annular blades. When the blades are opened, the blade tail is driven to open by the soil resistance.

[0018] Optionally, a welding plate is provided between the backs of the upper and lower blades. The welding plate is fixed in contact with the annular blade when the blade is opened to a set degree, and the blade as a whole is fan-shaped.

[0019] The present invention also provides a method for determining the bearing capacity of a steel pipe helical pile, applicable to the steel pipe helical pile described above, comprising:

[0020] Obtain parameter data for the insertion of steel pipe helical piles into the soil;

[0021] Based on the parameter data, determine the horizontal earth pressure and vertical shear force of the soil around the pile;

[0022] Based on the parameter data of the steel pipe helical pile, the horizontal soil pressure around the pile, and the vertical shear force of the soil around the pile, the tensile bearing capacity and compressive bearing capacity of the steel pipe helical pile are determined.

[0023] Optionally, obtaining the parameter data for the insertion of the steel pipe helical pile into the soil includes:

[0024] Obtain the soil unit weight γ of the steel pipe helical pile inserted into the soil, the soil at rest pressure K0, and the internal friction angle of the undisturbed soil particles above the superimposed blade. The internal friction angle of the disturbed soil particles above the superimposed blade. The cohesion c1 of the undisturbed soil particles above the superimposed leaves, the cohesion c2 of the disturbed soil particles above the superimposed leaves, and the calculated depth h of the steel pipe helical pile inserted into the soil from the ground surface are all considered.

[0025] Optionally, determining the horizontal earth pressure and vertical shear force around the pile based on the parameter data includes:

[0026] According to σ h =γhK0 determines the horizontal earth pressure around the pile;

[0027] according to Determine the shear force of the undisturbed soil;

[0028] according to Determine the shear force of the disturbed soil;

[0029] Where σh is the horizontal earth pressure around the pile, γ is the unit weight of the soil, h is the depth of the calculation location from the ground surface, and K0 is the earth pressure at rest. To calculate the internal friction angle of the undisturbed soil particles above the leaf, The internal friction angle of the disturbed soil particles above the superimposed leaf is given by c1, and the cohesion of the undisturbed soil particles above the superimposed leaf is given by c2. τ1 is the shear force of the undisturbed soil, and τ2 is the shear force of the disturbed soil.

[0030] Optionally, the pull-out bearing capacity of the steel pipe helical pile is determined based on the parameter data of the pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, including:

[0031] according to The standard value of the ultimate vertical uplift bearing capacity of a single pile is obtained;

[0032] according to The characteristic value of the vertical pull-out bearing capacity of a single pile is obtained;

[0033] Among them, T uk γ represents the standard value of the vertical pull-out ultimate bearing capacity of a single pile, γ is the unit weight of the soil, and l is the depth of the lowest blade of the steel pipe helical pile from the ground surface. To calculate the internal friction angle of the undisturbed soil particles above the leaf, The internal friction angle of the disturbed soil particles above the superimposed leaf is given by c1, and the cohesion of the undisturbed soil particles above the superimposed leaf is given by c2. μ1 is the total vertical projection perimeter of the superimposed blades, μ2 is the vertical projection perimeter of the helical blade minus the portion overlapping with the superimposed blades, and R a This represents the characteristic value of the vertical pull-out bearing capacity of a single pile.

[0034] Optionally, based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, the characteristic value of the compressive bearing capacity of the steel pipe helical pile is determined, including:

[0035] according to The standard value of the vertical compressive ultimate bearing capacity of a single pile is obtained;

[0036] according to The characteristic value of the vertical compressive bearing capacity of a single pile is obtained;

[0037] Among them, Q ukγ represents the standard value of the vertical compressive ultimate bearing capacity of a single pile, γ is the unit weight of the soil, and l is the depth of the lowest blade of the steel pipe helical pile from the ground surface. To calculate the internal friction angle of the undisturbed soil particles above the leaf, The internal friction angle of the disturbed soil particles above the superimposed leaf is given by c1, and the cohesion of the undisturbed soil particles above the superimposed leaf is given by c2. μ1 is the total vertical projection perimeter of the superimposed blades, μ2 is the vertical projection perimeter of the helical blade minus the portion overlapping with the superimposed blades, and q pk A represents the standard value of the ultimate end resistance of the soil at the pile tip. D R is the projected area of ​​the helical pile blade. b This represents the characteristic value of the vertical compressive bearing capacity of a single pile.

[0038] The above-described solution of the present invention has at least the following beneficial effects:

[0039] In the above-described scheme of the present invention, when the pile body is screwed into the soil in the forward direction, the superimposed blades contract, facilitating the smooth entry of the pile body into the soil. When the pile body is screwed into the soil to a set height and begins to reverse, the superimposed blades can open and embed themselves into the foundation soil. Compared with the traditional method of simply increasing the number of helical pile blades or increasing the area to improve the bearing capacity, the superimposed blades in the present invention, after opening and embedding into the foundation soil, can form a more effective interlocking and embedding effect with the foundation soil, utilizing the bearing potential of the original soil. Thus, without significantly increasing material consumption, the compressive and tensile bearing capacities of the steel pipe helical pile are significantly improved, especially in soft soil foundations where the advantages are more prominent.

[0040] This solution cleverly utilizes the special working method of stacked blades to enhance load-bearing capacity through a design that allows for retraction and expansion. It eliminates the need to significantly increase the number and area of ​​the helical pile blades, thereby reducing material usage and lowering costs.

[0041] Because the superimposed blades shrink as the pile is screwed in, the overall outer diameter of the pile is relatively small. Compared to the traditional method of increasing the number or area of ​​blades in a spiral pile, which leads to an increase in the outer diameter and screwing resistance, this method makes it easier for the pile to be screwed into the soil, reducing the difficulty of screwing in the pile during construction. Moreover, during construction, there is no need for complex equipment and processes to handle a large number of blades, making the operation simple, improving construction efficiency, and reducing construction time and labor costs.

[0042] The design of this steel pipe helical pile is more adaptable to different types of foundation soil, especially soft foundation soil. Through the ingenious design of superimposed blades, this scheme can effectively improve the bearing capacity of the pile in soft foundation without changing the basic structure and construction method of the pile, thus broadening the application range of steel pipe helical piles.

[0043] After the superimposed blades open and embed into the foundation soil, they increase the contact area and friction between the pile and the foundation soil, forming a tighter bond between the pile and the soil, thereby improving the overall stability of the pile. When subjected to external loads, this stable structure can more effectively transfer loads, reduce pile deformation and displacement, and ensure the safety of the superstructure. Attached Figure Description

[0044] Figure 1 This is a structural schematic diagram of the steel pipe helical pile of the present invention.

[0045] Figure 2 This is a schematic diagram of the superimposed blade contraction state of the steel pipe helical pile of the present invention.

[0046] Figure 3 This is a schematic diagram of the superimposed blades of the steel pipe helical pile of the present invention in the open state.

[0047] Figure 4 This is a flowchart of the method for determining the bearing capacity of the steel pipe spiral pile of the present invention.

[0048] Figure 5 This is a schematic diagram of the pull-out stress of the foundation soil in the method for determining the bearing capacity of the steel pipe helical pile of the present invention.

[0049] Figure 6 This is a schematic diagram of the shear strength lines of undisturbed soil and disturbed soil in the method for determining the bearing capacity of the steel pipe helical pile of the present invention.

[0050] Figure 7 This is a schematic diagram of the compressive stress of the soil in the method for determining the bearing capacity of the steel pipe helical pile of the present invention.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1. Pile body; 11. Steel pipe; 12. Conical head; 2. Helical pile blade; 21. Annular blade; 22. Hinged fastener; 3. Overlapping blade; 31. Blade; 311. Blade tail; 32. Welded plate. Detailed Implementation

[0053] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0054] like Figure 1 As shown, an embodiment of the present invention provides a steel pipe helical pile, comprising:

[0055] Pile body 1;

[0056] Multiple helical pile blades 2 are arranged around the pile body 1 along its axial direction;

[0057] Multiple stacked blades 3 are arranged to rotate radially along the helical pile blade 2;

[0058] The superimposed blades 3 contract when the pile body 1 is screwed into the soil in the forward direction, the pile body 1 begins to reverse after being screwed into a set depth, and the superimposed blades 3 open and embed into the foundation soil when the pile body 1 reverses. The tensile bearing capacity and compressive bearing capacity of the steel pipe helical pile are determined based on the parameter data of the steel pipe helical pile, the horizontal soil pressure around the pile after the superimposed blades 3 are unfolded, and the vertical shear force of the soil around the pile.

[0059] When the pile body 1 of this invention is screwed into the soil in the forward direction, the superimposed blades 3 contract, facilitating the smooth entry of the pile body 1 into the soil. When the pile body 1 is screwed into the soil to a set height and begins to reverse, the superimposed blades 3 can open and embed themselves into the foundation soil. Compared with the traditional method of simply increasing the number or area of ​​the spiral pile blades 2 to improve the bearing capacity, the superimposed blades 3 of this invention, after opening and embedding themselves into the foundation soil, can form a more effective interlocking and embedding effect with the foundation soil, utilizing the bearing potential of the original soil. Thus, without significantly increasing the material consumption, the compressive and tensile bearing capacities of the steel pipe spiral pile are significantly improved, especially in soft soil foundations where the advantages are more prominent.

[0060] This solution cleverly utilizes the special working method of the stacked blades 3, which can be retracted and expanded, to enhance the load-bearing capacity. It does not require a large increase in the number and area of ​​the helical pile blades 2, thus reducing the amount of materials used and lowering costs.

[0061] Because the superimposed blades 3 contract when the pile body 1 is screwed in, the overall outer diameter of the pile body 1 is relatively small. Compared with the traditional method of increasing the number or area of ​​the spiral pile blades 2, which leads to an increase in the outer diameter of the pile body 1 and an increase in screwing resistance, this scheme makes it easier for the pile body 1 to be screwed into the soil, reducing the difficulty of screwing the pile body 1 into the soil during construction. Moreover, during construction, there is no need for complex equipment and processes to handle a large number of blades, making the operation simple, improving construction efficiency, and reducing construction time and labor costs.

[0062] The design of this steel pipe helical pile is more adaptable to different types of foundation soil, especially soft foundation soil. Through the ingenious design of superimposed blades 3, this scheme can effectively improve the bearing capacity of pile 1 in soft foundation without changing the basic structure and construction method of pile 1, thus broadening the application range of steel pipe helical piles.

[0063] After the superimposed blades 3 open and embed into the foundation soil, they increase the contact area and friction between the pile 1 and the foundation soil, making the pile 1 and the soil form a tighter bond, thereby improving the overall stability of the pile 1. When subjected to external loads, this stable structure can more effectively transfer the load, reduce the deformation and displacement of the pile 1, and ensure the safety of the superstructure.

[0064] In an optional embodiment of the present invention, the pile body 1 includes:

[0065] A steel pipe 11, with multiple spiral pile blades 2 arranged around the steel pipe 11 along its axial direction;

[0066] A tapered head 12 is provided at the end of the steel pipe 11.

[0067] In this example, the pile body 1 is composed of a steel pipe 11 and a conical head 12 located at the pipe end. The steel pipe 11 has high strength and good durability, effectively transferring loads and resisting erosion. Its flexibility can adapt to foundation deformation, facilitating construction, connection, and recycling, and it is environmentally friendly. The conical head 12 has a guiding and positioning function, reducing the resistance to soil penetration, facilitating the vertical insertion of the pile body 1, and reducing construction difficulty and cost. At the same time, it enhances the interaction between the pile and the soil, improving bearing capacity and stability, and also protects the end of the pile body 1, preventing collision deformation and internal corrosion. The two work together to significantly optimize the performance of the pile body 1, providing a reliable guarantee for the engineering foundation.

[0068] like Figure 2 , Figure 3 As shown, in an optional embodiment of the present invention, the helical pile blade 2 includes:

[0069] An annular blade 21 is fixed to the steel pipe 11 at a set inclination. The annular blade 21 cuts into the soil at an angle downwards when the steel pipe 11 is rotated into the soil in the forward direction.

[0070] Multiple hinged fasteners 22 are provided on the annular blade 21, and the hinged fasteners 22 are rotatably connected to the superimposed blade 3.

[0071] In this example, the annular blade 21 is fixed to the steel pipe 11 at a set inclination. When the steel pipe 11 is screwed into the soil in the forward direction, its downward cutting motion is like a sharp blade, which can effectively cut the soil, greatly reduce the resistance to soil entry, improve construction efficiency, and ensure that the pile 1 can smoothly and quickly penetrate into the predetermined underground position.

[0072] Multiple hinged fasteners 22 mounted on the annular blades 21 are rotatably connected to the stacked blades 3, providing flexible working conditions for the stacked blades 3. During the pile body 1 screwing-in stage, the stacked blades 3 can retract without affecting the soil insertion operation; when the pile body 1 reaches the set height and reverses, the stacked blades 3 can smoothly open. This design not only ensures convenience in the early stage of construction but also realizes the function of improving the bearing capacity in the later stage.

[0073] The annular blade 21 and the superimposed blade 3 work together. During the bearing stage, the annular blade 21 increases the contact area between the pile body 1 and the soil, providing the foundation with friction and lateral bearing capacity. After the superimposed blade 3 opens, it further strengthens the pile-soil interlocking. The combination of the two greatly improves the compressive and tensile bearing capacity of the pile body 1, meeting the stringent requirements of the project for foundation stability.

[0074] like Figure 2 , Figure 3 As shown, in an optional embodiment of the present invention, the stacked blades 3 include:

[0075] The upper and lower blades 31 are rotatably connected to the hinged fastener 22. When the blades 31 are contracted, the other parts of the blades 31, except for the blade tail 311, overlap with the annular blades 21. When the blades 31 are opened, the blade tail 311 is driven to open by the soil resistance.

[0076] In this example, the pile body consists of two parts, upper and lower, and when it contracts, the parts other than the tail 311 overlap with the annular blade 21. During the forward spiraling of the pile body 1 into the soil, the overall outline of the superimposed blade 3 fits the annular blade 21, making the shape of the pile body 1 more compact, effectively reducing the resistance to soil penetration, allowing the pile body 1 to pass smoothly through various soil layers, reducing construction difficulty, and improving construction efficiency.

[0077] When the pile body 1 is screwed into the designated depth and reversed, the blade 31 opens. The blade tail 311 is driven to open by the soil resistance. This ingenious design requires no additional operation. It can automatically unfold the blade 31 by utilizing the natural resistance of the soil, saving manpower and construction time, while ensuring the accuracy and reliability of the timing of the unfolding of the superimposed blade 3.

[0078] After the blades 31 open, they increase the contact area and interlocking degree between the pile body 1 and the soil, greatly improving the pull-out and compressive bearing capacity of the pile body 1. Under complex geological conditions such as soft foundations, it can provide more stable support for buildings and structures, effectively reduce the risk of settlement and displacement, and ensure the long-term stability and safety of the engineering structure.

[0079] like Figure 2 , Figure 3As shown, in an optional embodiment of the present invention, a welding plate 32 is provided between the backs of the upper and lower blades 31. The welding plate 32 is fixed in contact with the annular blade 21 when the blades 31 are opened to a set degree. The blades 31 are fan-shaped in general.

[0080] In this example, a welding plate 32 is installed between the backs of the upper and lower blades 31. When the blades 31 open to a set degree, the welding plate 32 contacts and fixes to the annular blade 21, playing a crucial limiting role and ensuring that the opening angle of the blades 31 is accurate and stable. This prevents the blades 31 from affecting the overall performance of the pile body 1 due to excessive opening or shaking, and ensures that the superimposed blades 3 and the annular blades 21 form a stable cooperative structure in the working state, thereby improving the load-bearing capacity and stability of the pile body 1.

[0081] The blade 31 is fan-shaped, which increases the contact area with the soil when opened and more effectively distributes the load on the pile 1 evenly into the surrounding soil. Compared with blades of ordinary shape, the fan-shaped design significantly improves the tensile and compressive bearing capacity of the pile 1, making it particularly suitable for construction projects with high foundation bearing capacity requirements, and effectively reducing the risk of settlement and tilting of the pile 1.

[0082] The way the welding plate 32 is fixed to the annular blade 21 ensures that the blade 31 will not accidentally close or loosen when subjected to complex loads and soil action over a long period of time. Under various harsh geological conditions, it can reliably enhance the load-bearing capacity, providing a solid guarantee for the long-term stable operation of the engineering foundation.

[0083] When designing building structures, it is necessary to verify whether the vertical bearing capacity of the pile foundation meets the design requirements. That is, the vertical compressive force on the pile foundation must be less than the characteristic value of the pile foundation's vertical bearing capacity, and the vertical uplift force on the pile foundation must be less than the sum of the characteristic value of the pile foundation's vertical bearing capacity and the pile foundation's self-weight. During construction, understanding the bearing capacity of steel pipe helical piles can help construction personnel rationally select construction equipment and techniques, avoiding construction accidents caused by insufficient pile bearing capacity.

[0084] The steel pipe helical pile of the present invention has a unique structure, including annular blades 21 and rotatably connected superimposed blades 3. Conventional methods do not consider the complex influence of the inclination of the annular blades 21, the contraction and opening of the superimposed blades 3, and the limiting effect of the welded plate 32 on the bearing capacity. For example, the effect of changes in the contact area and interlocking degree between the superimposed blades 3 and the soil when they are opened on the improvement of bearing capacity is difficult to determine accurately using conventional methods.

[0085] Ordinary piles primarily bear vertical pressure or tension, while the steel pipe helical piles of this invention, in addition to vertical forces, also bear significant torque and lateral forces due to the helical structure during screwing in and bearing load. Conventional determination methods cannot accurately account for the interaction of these complex forces and their impact on bearing capacity. For example, torque can alter the stress state of the soil around the pile, affecting the pile-soil friction and the overall stability of the pile.

[0086] The driving of spiral steel pipe piles creates unique compression and disturbance effects on the surrounding soil, causing changes in the physical and mechanical properties of the soil that differ from those of conventional piles. Conventional methods cannot accurately account for the impact of these soil property changes on bearing capacity caused by this special construction method. For example, in soft soil, the strength of the soil around the pile may increase to some extent due to compression, unlike the soil disturbance during the construction of conventional piles.

[0087] like Figure 4 As shown, the present invention also provides a method for determining the bearing capacity of a steel pipe helical pile, applied to the steel pipe helical pile described above, comprising:

[0088] Step 11: Obtain parameter data for inserting the steel pipe helical pile into the soil;

[0089] Step 12: Determine the horizontal earth pressure and vertical shear force of the soil around the pile based on the parameter data.

[0090] Step 13: Based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, determine the tensile bearing capacity and compressive bearing capacity of the steel pipe helical pile. Due to the special structure of the steel pipe helical pile, its bearing capacity is determined by two parts: the shear strength of the undisturbed soil above the superimposed blade 3 and the residual strength of the disturbed soil above the helical pile blade 2.

[0091] Specifically, obtaining the parameter data for inserting the steel pipe helical pile into the soil includes:

[0092] Obtain the soil unit weight γ of the steel pipe helical pile inserted into the soil, the soil at rest earth pressure K0, and the internal friction angle of the undisturbed soil particles above the superimposed blade 3. The internal friction angle of the soil particles above the superimposed blade 3 is the disturbed soil parameter. The cohesion c1 of the undisturbed soil particles above the superimposed leaf 3, the cohesion c2 of the disturbed soil particles above the superimposed leaf 3, and the calculated depth h of the steel pipe helical pile inserted into the soil from the ground surface.

[0093] The soil that undergoes compression and cutting during the insertion of the steel pipe helical pile, causing changes in its original structure and physical and mechanical properties, is called disturbed soil. The undisturbed foundation soil that retains its natural structure and state is called undisturbed soil.

[0094] The step of determining the horizontal earth pressure and vertical shear force around the pile based on the parameter data includes:

[0095] According to σ h =γhK0 determines the horizontal earth pressure around the pile;

[0096] according to Determine the shear force of the undisturbed soil;

[0097] according to Determine the shear force of the disturbed soil;

[0098] Where, σ h Let γ be the horizontal earth pressure around the pile, γ be the soil unit weight, h be the depth of the calculation location from the ground surface, and K0 be the earth pressure at rest. To calculate the internal friction angle of the undisturbed soil particles above leaf 3, To superimpose the internal friction angle of the disturbed soil particles above leaf 3 c1 represents the cohesive force of the undisturbed soil particles above the superimposed leaf 3, and c2 represents the cohesive force of the disturbed soil particles above the superimposed leaf 3 (c1 > c2). τ1 is the shear force of the undisturbed soil, and τ2 is the shear force of the disturbed soil.

[0099] like Figure 5 , Figure 6 As shown, based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, the pull-out bearing capacity of the steel pipe helical pile is determined, including:

[0100] according to The standard value of the ultimate vertical uplift bearing capacity of a single pile is obtained;

[0101] according to The characteristic value of the vertical pull-out bearing capacity of a single pile is obtained;

[0102] Among them, T uk γ represents the standard value of the vertical pull-out ultimate bearing capacity of a single pile, γ is the unit weight of the soil, and l is the depth of the lowest blade of the steel pipe helical pile from the ground surface. To calculate the internal friction angle of the undisturbed soil particles above leaf 3, To superimpose the internal friction angle of the disturbed soil particles above leaf 3 c1 represents the cohesive force of the undisturbed soil particles above the superimposed leaf 3, and c2 represents the cohesive force of the disturbed soil particles above the superimposed leaf 3 (c1 > c2). μ1 is the total vertical projection perimeter of the superimposed blade 3, μ2 is the vertical projection perimeter of the helical pile blade 2 minus the portion overlapping with the superimposed blade 3, and R a This represents the characteristic value of the vertical pull-out bearing capacity of a single pile.

[0103] Specifically, the horizontal earth pressure σ around the steel pipe helical pile h =γhK0, Vertical shear force of soil surrounding the steel pipe helical pile Differential dh ring pile one circumference vertical Integrating the calculation depth h from the ground surface to the depth l of the lowest blade, the bearing capacity of the undisturbed soil above the superimposed blade 3 and the bearing capacity of the disturbed soil above the helical pile blade 2 are calculated respectively:

[0104]

[0105] Substituting the strength parameters of the undisturbed soil and the disturbed soil, we obtain the standard value of the ultimate tensile bearing capacity of the pile:

[0106]

[0107] Characteristic value of vertical uplift bearing capacity of a single pile

[0108] In determining the horizontal earth pressure and vertical shear force around the pile, multiple parameters were fully considered, including soil unit weight, at-rest earth pressure, internal friction angle and cohesion of soil particles under different conditions (undisturbed soil and disturbed soil), and the depth of the calculation location from the ground surface. Shear force was calculated separately for undisturbed soil and disturbed soil. Furthermore, when determining the uplift bearing capacity, the different mechanical properties of the undisturbed soil above the superimposed blade 3 and the disturbed soil above the helical pile blade 2 were distinguished, making the calculation model closer to actual conditions. This improved the accuracy of the description of the mechanical properties of the soil around the pile, and consequently enhanced the accuracy of the calculation of the uplift bearing capacity of the steel pipe helical pile. This approach more accurately reflects the interaction between the steel pipe helical pile and the soil under actual working conditions, providing a more reliable basis for engineering design.

[0109] A differential method was adopted to calculate the vertical bearing capacity of the pile ring (dh) from the ground surface to the depth l of the lowest blade, and the integral method was used to calculate the bearing capacity of the undisturbed soil above the superimposed blade 3 and the disturbed soil above the helical pile blade 2, respectively. This analytical method based on calculus and soil mechanics comprehensively and deeply considers the interaction mechanism between the pile and the soil from a theoretical perspective, and conducts a detailed analysis and integration of the forces acting on the pile, ensuring the scientificity and rationality of the determination method and providing a solid theoretical foundation for the bearing capacity determination process.

[0110] This method is adaptable to different soil conditions (such as soils with different unit weights, internal friction angles, and cohesion) and different working states (pull-out conditions) of steel pipe helical piles. By substituting the corresponding actual parameters, the pull-out bearing capacity of steel pipe helical piles can be accurately determined in various complex and variable engineering environments. It can provide relatively accurate calculation results in areas with simple or complex geological conditions, demonstrating strong applicability and expanding the application scope of this method to meet the needs of different projects for calculating the bearing capacity of steel pipe helical piles.

[0111] The characteristic value of the vertical uplift bearing capacity of a single pile is obtained by dividing the standard value of the ultimate vertical uplift bearing capacity of a single pile by a safety factor. This safety factor is generally taken as around 2. This is done to ensure that, in actual engineering projects, the pile has sufficient safety margin when bearing the design load, guaranteeing that the pile foundation is sufficiently stable and reliable.

[0112] The bearing capacity calculation of the steel pipe helical pile is closely focused on its unique structure, including the superimposed blades (3). Parameters related to the pile structure, such as the total vertical projection perimeter of the superimposed blades (3) and the vertical projection perimeter of the helical pile blades (2 minus the overlapping portion with the superimposed blades (3)), are introduced. The introduction of these parameters allows the calculation method to better reflect the mechanical characteristics of this special pile type and more accurately represent the interaction between the pile structure and the soil, thus providing a more targeted basis for the structural optimization design of steel pipe helical piles.

[0113] like Figure 6 , Figure 7 As shown, based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, the characteristic value of the compressive bearing capacity of the steel pipe helical pile is determined, including:

[0114] according to The standard value of the vertical compressive ultimate bearing capacity of a single pile is obtained;

[0115] according to The characteristic value of the vertical compressive bearing capacity of a single pile is obtained;

[0116] Among them, Q uk γ represents the standard value of the vertical compressive ultimate bearing capacity of a single pile, γ is the unit weight of the soil, and l is the depth of the lowest blade of the steel pipe helical pile from the ground surface. To calculate the internal friction angle of the undisturbed soil particles above leaf 3, To superimpose the internal friction angle of the disturbed soil particles above leaf 3 c1 represents the cohesive force of the undisturbed soil particles above the superimposed leaf 3, and c2 represents the cohesive force of the disturbed soil particles above the superimposed leaf 3 (c1 > c2). μ1 is the total vertical projection perimeter of the superimposed blade 3, μ2 is the vertical projection perimeter of the helical pile blade 2 minus the portion overlapping with the superimposed blade 3, and q pk A represents the standard value of the ultimate end resistance of the soil at the pile tip. D R is the projected area of ​​the helical pile blade 2. b This represents the characteristic value of the vertical compressive bearing capacity of a single pile.

[0117] Specifically, the horizontal earth pressure σ around the steel pipe helical pile h =γhK0, Vertical shear force of soil surrounding the steel pipe helical pile Differential dh ring pile one circumference vertical The compressive bearing capacity of the pile side is obtained by integrating the calculation location depth h from the ground surface to the depth l of the lowest blade:

[0118]

[0119] Substituting the strength parameters of the undisturbed soil and the disturbed soil, the bearing capacity of the undisturbed soil above the superimposed blade 3 and the bearing capacity of the disturbed soil above the helical pile blade 2 are calculated respectively. Then, these values ​​are summed with the pile tip bearing capacity to obtain the standard value of the overall compressive ultimate bearing capacity of the single pile.

[0120]

[0121] Characteristic value of vertical compressive bearing capacity of a single pile

[0122] This method comprehensively considers numerous parameters of the steel pipe helical pile, such as soil unit weight, depth of the lowest blade of the steel pipe helical pile from the ground surface, relevant parameters of the superimposed blade 3 and the helical pile blade 2, as well as the horizontal earth pressure and vertical shear force around the pile. By distinguishing between the undisturbed soil above the superimposed blade 3 and the disturbed soil above the helical pile blade 2, and considering their different internal friction angles and cohesion, it can more accurately reflect the complex interaction between the steel pipe helical pile and the surrounding soil under compression. This makes the calculation results more consistent with the actual stress conditions and provides a reliable basis for engineering design.

[0123] The compressive bearing capacity of the pile side is calculated by taking the vertical direction of the pile dh ring using differential calculus and integrating the calculation depth h from the ground surface to the depth l of the lowest blade. This analytical method based on calculus and soil mechanics comprehensively and deeply considers the contribution of the mechanical properties of the soil at different locations on the pile side compressive bearing capacity. It ensures the scientificity and rationality of the method from a theoretical perspective, and provides a solid theoretical foundation for the determination of compressive bearing capacity.

[0124] This method is adaptable to various soil conditions (soils with different unit weights, internal friction angles, and cohesion) and the actual working state of steel pipe helical piles. For different engineering sites, simply substituting the corresponding actual parameters allows for accurate determination of the compressive bearing capacity of steel pipe helical piles under various complex geological environments. It provides relatively accurate calculation results in both soft and hard soil foundations, demonstrating strong applicability and expanding the application scope of this method to meet the needs of different engineering projects for calculating the compressive bearing capacity of steel pipe helical piles.

[0125] When calculating the standard value of the vertical compressive ultimate bearing capacity of a single pile, not only is the compressive bearing capacity of the pile side (including the contributions of undisturbed soil and disturbed soil) considered, but also the important factor of the standard value of the ultimate end resistance of the pile tip soil is incorporated. This comprehensive consideration of the bearing capacity of the pile body and pile tip allows for a more accurate assessment of the overall compressive performance of the steel pipe helical pile, avoiding the situation where only the pile side resistance is considered while ignoring the influence of the pile tip resistance on the bearing capacity, thus making the assessment results more reliable and comprehensive.

[0126] The characteristic value of the vertical compressive bearing capacity of a single pile is determined based on the standard value of the ultimate vertical compressive bearing capacity of a single pile. Because in actual engineering projects, there are many uncertain factors, such as uneven soil properties and varying loads, a safety factor is introduced to ensure the safety of the pile foundation in actual use. The characteristic value of the vertical compressive bearing capacity of a single pile is obtained by dividing the standard value of the ultimate vertical compressive bearing capacity of the single pile by the safety factor. The value of the safety factor is not fixed and is determined based on factors such as the importance of the project and the complexity of the geological conditions; it is generally around 2.

[0127] This method closely integrates the unique structure of the steel pipe helical pile (such as superimposed blade 3 and helical pile blade 2) to calculate its compressive bearing capacity, introducing key parameters related to the pile structure. These parameters accurately reflect the influence of the pile structure on its compressive performance, providing detailed and accurate basis for the structural optimization design of steel pipe helical piles. Engineers can adjust and improve the pile structure based on the calculation results to further enhance the compressive bearing capacity and overall performance of the steel pipe helical pile, reduce engineering costs, and improve engineering efficiency.

[0128] This invention fully considers multiple parameters such as soil unit weight, static earth pressure, internal friction angle of soil particles, and cohesion, distinguishes between undisturbed soil and disturbed soil, accurately describes the mechanical properties of the soil around the pile, improves the calculation accuracy of the pull-out and compressive bearing capacity of steel pipe helical piles, and more accurately reflects the interaction between piles and soil, providing a reliable basis for engineering design.

[0129] Based on the principles of calculus and soil mechanics, this method employs differential calculus to obtain infinitesimal elements and then integrates them to comprehensively and thoroughly consider the pile-soil interaction mechanism. It also provides a detailed analysis and integration of the pile's stress, ensuring the scientific validity and rationality of the determination method and providing a solid theoretical foundation for the bearing capacity determination process.

[0130] It can adapt to different soil conditions (such as soils with different unit weights, internal friction angles, and cohesion) and the working states of steel pipe helical piles (tension resistance and compressive resistance). By substituting actual parameters, the bearing capacity can be accurately determined in various complex engineering environments. Whether in simple or complex geological areas, it can provide relatively accurate calculation results and meet the bearing capacity calculation needs of different projects.

[0131] When determining the characteristic values ​​of the vertical tensile and compressive bearing capacity of a single pile, a safety factor (generally about 2) is introduced to take into account uncertainties such as uneven soil properties and load fluctuations in actual engineering projects, and to reserve sufficient safety margin to ensure the stability and reliability of the pile foundation and improve the safety and reliability of the engineering structure.

[0132] When calculating the compressive bearing capacity, not only is the compressive bearing capacity of the pile side (including the contribution of undisturbed soil and disturbed soil) considered, but the standard value of the ultimate end resistance of the pile tip soil is also included. This comprehensively evaluates the overall compressive performance of the steel pipe helical pile, avoids ignoring the influence of the pile tip resistance, and makes the evaluation results more reliable and comprehensive.

[0133] By closely combining the special structure of steel pipe helical piles (such as superimposed blade 3 and helical pile blade 2) to calculate the bearing capacity, and introducing key parameters related to the pile structure, the influence of the structure on the compressive and tensile performance is accurately reflected. This provides a detailed and accurate basis for the optimized design of the pile structure. Engineers can adjust and improve the pile structure accordingly to enhance the bearing capacity and overall performance, reduce project costs, and improve project efficiency.

[0134] Example 1

[0135] According to the geotechnical investigation report, the unit weight of the foundation sandy soil for a photovoltaic project in a certain area is 18 kN / m³. 3 The internal friction angle of the undisturbed soil is 24°, the internal friction angle of the disturbed soil is 17°, the cohesion is 0 kPa, the lowest layer of stacked blades is 2.5 m from the ground surface, the pile foundation penetration depth is 2.6 m, and the standard value of the ultimate lateral resistance of the foundation sand is q. sk The maximum pressure is 18 kPa. The total projected perimeter of the superimposed blade 3 is 1.2 m. The vertical projected perimeter of the helical pile blade 2 minus the overlapping part with the superimposed blade 3 is 0.6 m. The standard value of the ultimate end resistance of the pile tip soil is 900 kPa. The projected area of ​​the helical pile blade 2 is 0.04 m2.

[0136] (1) Standard value of the ultimate vertical uplift bearing capacity of a single pile:

[0137]

[0138] Characteristic value of vertical uplift bearing capacity of a single pile

[0139] (2) Standard value of vertical compressive ultimate bearing capacity of a single pile:

[0140]

[0141] Characteristic value of vertical compressive bearing capacity of a single pile

[0142] This method for determining bearing capacity, based on the unique structural characteristics of this pile type, introduces parameters such as the total circumference of the vertical projection of the superimposed blade 3. This allows for a more accurate reflection of the interaction between the pile body 1 and the soil, thus more precisely determining the bearing capacity. It fully considers various soil properties, such as unit weight, at-rest earth pressure, internal friction angle, cohesion, and the standard value of the ultimate end resistance of the soil at the pile tip. These parameters comprehensively reflect the mechanical properties of the soil under different geological conditions, making the determination results more consistent with actual engineering conditions and applicable to various complex geological environments. Accurately determining the characteristic values ​​of the vertical tensile bearing capacity and the vertical compressive bearing capacity of a single pile provides a reliable basis for engineering design.

[0143] It should be noted that this method corresponds to the method described above for steel pipe helical piles. All implementation methods in the above steel pipe helical pile embodiments are applicable to the embodiments of this method and can achieve the same technical effect.

[0144] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A steel pipe helical pile, characterized in that, include: Pile body (1); Multiple helical pile blades (2) are arranged around the pile body (1) along its axial direction; Multiple stacked blades (3) are arranged to rotate radially along the helical pile blade (2); The superimposed blades (3) contract when the pile body (1) is screwed into the soil in the forward direction, the pile body (1) begins to reverse after being screwed into a set depth, and the superimposed blades (3) open and embed into the foundation soil when the pile body (1) reverses; the tensile bearing capacity and compressive bearing capacity of the steel pipe helical pile are determined based on the parameter data of the steel pipe helical pile, the horizontal soil pressure around the pile after the superimposed blades (3) are unfolded, and the vertical shear force of the soil around the pile. The pile body (1) includes: A steel pipe (11) is provided, and multiple helical pile blades (2) are arranged around the steel pipe (11) along its axial direction; A conical head (12) is provided at the pipe end of the steel pipe (11); The helical pile blade (2) includes: An annular blade (21) is fixed to the steel pipe (11) at a set inclination. The annular blade (21) cuts into the soil at an angle downwards when the steel pipe (11) is rotated into the soil in the forward direction. Multiple hinged fasteners (22) are provided on the annular blade (21), and the hinged fasteners (22) are rotatably connected to the superimposed blade (3); The superimposed blades (3) include: The upper and lower blades (31) are rotatably connected to the hinged fastener (22). When the blades (31) are contracted, the other parts except the blade tail (311) overlap with the annular blades (21). When the blades (31) are opened, the blade tail (311) is driven by the soil resistance to open the blades (31).

2. The steel pipe spiral pile according to claim 1, characterized in that, A welding plate (32) is provided between the backs of the upper and lower blades (31). The welding plate (32) is fixed in contact with the annular blade (21) when the blade (31) is opened to a set degree. The blade (31) is fan-shaped as a whole.

3. A method for determining the bearing capacity of a steel pipe helical pile, applied to the steel pipe helical pile according to any one of claims 1 to 2, characterized in that, include: Obtain parameter data for the insertion of steel pipe helical piles into the soil; Based on the parameter data, determine the horizontal earth pressure and vertical shear force of the soil around the pile; Based on the parameter data of the steel pipe helical pile, the horizontal soil pressure around the pile, and the vertical shear force of the soil around the pile, the tensile bearing capacity and compressive bearing capacity of the steel pipe helical pile are determined.

4. The method for determining the bearing capacity of a steel pipe spiral pile according to claim 3, characterized in that, The acquisition of parameter data for the insertion of steel pipe helical piles into the soil includes: Obtain the soil unit weight of the steel pipe helical piles inserted into the soil. Earth pressure at rest in soil K 0. The internal friction angle of the undisturbed soil particles above the superimposed leaf (3) 1. The internal friction angle of soil particles above the superimposed leaf (3) 2. Cohesion of the original soil particles above the superimposed leaf (3) c 1. Cohesion of disturbed soil particles above the superimposed leaf (3) c 2. The calculated depth of the steel pipe helical piles inserted into the soil from the ground surface. h .

5. The method for determining the bearing capacity of a steel pipe spiral pile according to claim 4, characterized in that, The step of determining the horizontal earth pressure and vertical shear force around the pile based on the parameter data includes: according to Determine the horizontal earth pressure around the pile; according to Determine the shear force of the undisturbed soil; according to Determine the shear force of the disturbed soil; in, The horizontal earth pressure around the pile. The bulk density of the soil, h To calculate the depth of the location from the Earth's surface, K 0 represents the earth pressure at rest. 1 represents the internal friction angle of the undisturbed soil particles above the superimposed leaf (3). 2 represents the internal friction angle of the soil particles above the superimposed leaf (3). c 1 represents the cohesion of the undisturbed soil particles above the superimposed leaf (3). c 2 represents the cohesion of the disturbed soil particles above the superimposed leaf (3). , 1 represents the shear force of the undisturbed soil. 2 represents the shear force of the disturbed soil.

6. The method for determining the bearing capacity of a steel pipe spiral pile according to claim 5, characterized in that, Based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, the pull-out bearing capacity of the steel pipe helical pile is determined, including: according to The standard value of the ultimate vertical uplift bearing capacity of a single pile is obtained; according to The characteristic value of the vertical pull-out bearing capacity of a single pile is obtained; in, This represents the standard value of the ultimate vertical uplift bearing capacity of a single pile. The bulk density of the soil, This refers to the depth of the lowest blade of the steel pipe helical pile from the ground surface. 1 represents the internal friction angle of the undisturbed soil particles above the superimposed leaf (3). 2 represents the internal friction angle of the soil particles above the superimposed leaf (3). c 1 represents the cohesion of the undisturbed soil particles above the superimposed leaf (3). c 2 represents the cohesion of the disturbed soil particles above the superimposed leaf (3). , 1 represents the total circumference of the vertical projection of the superimposed blade (3). 2 is the vertical projection perimeter of the helical pile blade (2) minus the overlapping portion with the superimposed blade (3). This represents the characteristic value of the vertical pull-out bearing capacity of a single pile.

7. The method for determining the bearing capacity of a steel pipe spiral pile according to claim 6, characterized in that, Based on the parameter data of the steel pipe helical pile, the horizontal earth pressure around the pile, and the vertical shear force of the soil around the pile, the characteristic value of the compressive bearing capacity of the steel pipe helical pile is determined, including: according to The standard value of the vertical compressive ultimate bearing capacity of a single pile is obtained; according to The characteristic value of the vertical compressive bearing capacity of a single pile is obtained; in, This represents the standard value of the ultimate vertical compressive bearing capacity of a single pile. The bulk density of the soil, This refers to the depth of the lowest blade of the steel pipe helical pile from the ground surface. 1 represents the internal friction angle of the undisturbed soil particles above the superimposed leaf (3). 2 represents the internal friction angle of the soil particles above the superimposed leaf (3). c 1 represents the cohesion of the undisturbed soil particles above the superimposed leaf (3). c 2 represents the cohesion of the disturbed soil particles above the superimposed leaf (3). , 1 represents the total circumference of the vertical projection of the superimposed blade (3). 2 is the vertical projection perimeter of the helical pile blade (2) minus the overlapping portion with the superimposed blade (3). This represents the standard value of the ultimate end resistance of the soil at the pile tip. The projected area of ​​the helical pile blade (2) is... This represents the characteristic value of the vertical compressive bearing capacity of a single pile.

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