Steel pipe screw pile and method for determining bearing capacity of steel pipe screw pile

Abstract

The invention provides a steel pipe screw pile and a method for determining the bearing capacity of the steel pipe screw pile. The steel pipe screw pile comprises a pile body; the spiral pile blades are arranged in a surrounding mode in the axial direction of the pile body; the multiple overlapped blades are rotationally arranged in the radial direction of the spiral pile blade; wherein the overlaid blades contract when the pile body is screwed into soil in the forward direction, the pile body starts to rotate reversely when the pile body is screwed into the set depth, and the overlaid blades expand and are embedded into foundation soil when the pile body rotates reversely; wherein the uplift bearing capacity and the compression bearing capacity of the steel pipe screw pile are determined according to the parameter data of the steel pipe screw pile, the horizontal soil pressure of soil around the pile after the overlapped blades are unfolded and the vertical shearing force of the soil around the pile. The steel pipe screw pile can form more effective occlusion and build-in effects with foundation soil, and the compressive bearing capacity and the uplift bearing capacity of the steel pipe screw pile are remarkably improved on the premise of not remarkably increasing consumables by utilizing the bearing potential of undisturbed soil.

Description

Technical Field

[0001] The present invention relates to the technical field of steel pipe screw piles, and particularly to a steel pipe screw pile and a method for determining its bearing capacity. Background Art

[0002] A steel pipe screw pile is a basic engineering material combining a steel pipe and a screw pile blade structure, mainly used for foundation reinforcement, load transfer, and structural support. Its core feature lies in the combined action of the screw pile blade and the steel pipe, forming a stable soil-pile combination by screwing into the soil, thereby enhancing the bearing capacity and uplift resistance.

[0003] Currently, when faced with soft soil foundations and the need to improve the compressive and uplift bearing capacities of steel pipe screw piles, generally, the number of screw pile blades is increased or the area is enlarged, resulting in a large amount of material consumption and increasing the difficulty of screwing the steel pipe screw pile 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 screw pile and a method for determining its bearing capacity, which can form a more effective biting and anchoring effect with the foundation soil, utilize the bearing potential of the undisturbed soil, and significantly improve the compressive and uplift bearing capacities of the steel pipe screw pile without significantly increasing the material consumption.

[0005] To solve the above technical problem, the technical solution of the present invention is as follows: A steel pipe screw pile, comprising:

[0006] A pile body;

[0007] A plurality of screw pile blades axially wound around the pile body;

[0008] A plurality of superimposed blades rotatably arranged radially along the screw pile blades;

[0009] Wherein, the superimposed blades contract when the pile body is screwed into the soil in the forward direction, the pile body starts to reverse when it is screwed into a set depth, and the superimposed blades open and embed into the foundation soil when the pile body reverses; wherein, the uplift bearing capacity and compressive bearing capacity of the steel pipe screw pile are determined according to the parameter data of the steel pipe screw pile, the horizontal earth pressure of the soil 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 a plurality of screw pile blades axially wound around the steel pipe;

[0012] A conical head provided at the pipe head of the steel pipe.

[0013] Optionally, the screw pile blade includes:

[0014] Annular blades, which are fixed on the steel pipe at a set inclination, and cut obliquely downward when the steel pipe is screwed into the soil forward;

[0015] Multiple hinged fixing parts arranged on the annular blades, and the hinged fixing parts are rotatably connected with the superimposed blades.

[0016] Optionally, the superimposed blades include:

[0017] Two upper and lower blades rotatably connected with the hinged fixing parts. When the blades contract, other parts except the blade tails overlap with the annular blades. When the blades open, the blade tails are driven by the soil resistance to open the blades.

[0018] Optionally, a welding plate is provided between the backs of the two upper and lower blades. The welding plate contacts and fixes with the annular blade when the blades open to a set degree, and the blades are integrally in the shape of a fan blade.

[0019] The present invention also provides a method for determining the bearing capacity of a steel pipe screw pile, which is applied to the steel pipe screw pile as described above, and includes:

[0020] Obtain the parameter data of the steel pipe screw pile inserted into the soil;

[0021] According to the parameter data, determine the horizontal soil pressure of the soil around the pile and the vertical shear force of the soil around the pile;

[0022] According to the parameter data of the steel pipe screw pile, the horizontal soil pressure of the soil around the pile and the vertical shear force of the soil around the pile, determine the uplift bearing capacity and the compressive bearing capacity of the steel pipe screw pile.

[0023] Optionally, the obtaining of the parameter data of the steel pipe screw pile inserted into the soil includes:

[0024] Obtain the soil unit weight γ of the steel pipe screw pile inserted into the soil, the coefficient of earth pressure at rest K0 of the soil, and the internal friction angle of the original soil particles above the superimposed blades The internal friction angle of the disturbed soil parameters of the soil particles above the superimposed blades The cohesion c1 of the original soil particles above the superimposed blades, the cohesion c2 of the disturbed soil particles above the superimposed blades, and the depth h from the calculation position of the steel pipe screw pile inserted into the soil to the ground surface.

[0025] Optionally, the determining of the horizontal soil pressure of the soil around the pile and the vertical shear force of the soil around the pile according to the parameter data includes:

[0026] According to σ h =γhK0 to determine the horizontal soil pressure of the soil around the pile;

[0027] According to Determine the shear force of the original soil;

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

[0029] Wherein, σh is the horizontal soil pressure of the soil around the pile, γ is the unit weight of the soil, h is the depth from the calculation position to the ground surface, K0 is the coefficient of earth pressure at rest, is the internal friction angle of the undisturbed soil particles above the superimposed blade, is the internal friction angle of the disturbed soil parameter particles above the superimposed blade, c1 is the cohesion of the undisturbed soil particles above the superimposed blade, c2 is the cohesion of the disturbed soil particles above the superimposed blade, τ1 is the shear force of the undisturbed soil, τ2 is the shear force of the disturbed soil.

[0030] Optionally, according to the parameter data of the steel pipe screw pile, the horizontal soil pressure of the soil around the pile and the vertical shear force of the soil around the pile, determine the uplift bearing capacity of the steel pipe screw pile, including:

[0031] According to Obtain the standard value of the ultimate vertical uplift bearing capacity of a single pile;

[0032] According to Obtain the characteristic value of the vertical uplift bearing capacity of a single pile;

[0033] Wherein, T uk is the standard value of the ultimate vertical uplift bearing capacity of a single pile, γ is the unit weight of the soil, l is the depth from the lowest blade of the steel pipe screw pile to the ground surface, is the internal friction angle of the undisturbed soil particles above the superimposed blade, is the internal friction angle of the disturbed soil parameter particles above the superimposed blade, c1 is the cohesion of the undisturbed soil particles above the superimposed blade, c2 is the cohesion of the disturbed soil particles above the superimposed blade, μ1 is the total vertical projected perimeter of the superimposed blade, μ2 is the vertical projected perimeter of the screw pile blade minus the overlapping part with the superimposed blade, R a is the characteristic value of the vertical compressive bearing capacity of a single pile.

[0034] Optionally, according to the parameter data of the steel pipe screw pile, the horizontal soil pressure of the soil around the pile and the vertical shear force of the soil around the pile, determine the characteristic value of the compressive bearing capacity of the steel pipe screw pile, including:

[0035] According to Obtain the standard value of the ultimate vertical compressive bearing capacity of a single pile;

[0036] According to Obtain the characteristic value of the vertical compressive bearing capacity of a single pile;

[0037] Wherein, Q ukis the standard value of the ultimate vertical compressive bearing capacity of a single pile, γ is the unit weight of the soil, l is the depth from the lowest blade of the steel pipe screw pile to the ground surface, is the internal friction angle of the original soil particles above the superimposed blades, is the internal friction angle of the disturbed soil parameters of the soil particles above the superimposed blades, c1 is the cohesion of the original soil particles above the superimposed blades, and c2 is the cohesion of the disturbed soil particles above the superimposed blades, μ1 is the total vertical projection perimeter of the superimposed blades, μ2 is the vertical projection perimeter of the screw pile blades minus the overlapping part with the superimposed blades, q pk is the standard value of the ultimate tip resistance of the pile tip soil, A D is the projected area of the screw pile blades, R b is the characteristic value of the vertical compressive bearing capacity of a single pile.

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

[0039] In the above scheme of the present invention, when the pile body of the present invention 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 starts to reverse after being screwed into the set height, the superimposed blades can open and embed into the foundation soil. Compared with the traditional method of solely relying on increasing the number or area of the screw pile blades to improve the bearing capacity, after the superimposed blades of the present invention open and embed into the foundation soil, they can form a more effective biting and anchoring effect with the foundation soil, utilizing the bearing potential of the original soil, thereby significantly improving the compressive and uplift bearing capacities of the steel pipe screw pile without significantly increasing the consumption of materials, especially showing more advantages in soft soil foundations.

[0040] Through the design of the retractable and expandable superimposed blades, this scheme cleverly utilizes the special working mode of the superimposed blades to enhance the bearing capacity, without the need to significantly increase the number and area of the screw pile blades, reducing the material usage and cost.

[0041] Since the superimposed blades contract when the pile body is screwed into the soil in the forward direction, the overall outer diameter of the pile body is relatively small. Compared with the situation where the outer diameter of the pile body increases and the screwing resistance increases due to significantly increasing the number or area of the screw pile blades in the traditional method, this scheme is more conducive to the pile body being screwed into the soil, reducing the difficulty of screwing the pile body during the construction process. Moreover, during the construction process, there is no need for complex equipment and processes to handle a large number of blades, the operation is simple, which can improve the construction efficiency and reduce the construction time and labor cost.

[0042] The design of this steel pipe screw pile has better adaptability to different types of foundation soils, especially soft foundation soils. Through the ingenious design of the superimposed blades, this scheme can effectively improve the bearing performance of the pile body in soft foundation soils without changing the basic structure and construction method of the pile body, broadening the application range of the steel pipe screw pile.

[0043] After the superimposed blades open and embed into the foundation soil, the contact area and friction between the pile body and the foundation soil are increased, forming a tighter combination between the pile body and the soil, thereby improving the overall stability of the pile body. When bearing external loads, this stable structure can transfer the loads more effectively, reduce the deformation and displacement of the pile body, and ensure the safety of the superstructure. Brief Description of the Drawings

[0044] Figure 1 is a schematic structural view of the steel pipe screw pile of the present invention.

[0045] Figure 2 is a schematic structural view of the superimposed blades of the steel pipe screw pile of the present invention in a contracted state.

[0046] Figure 3 is a schematic structural view of the superimposed blades of the steel pipe screw pile of the present invention in an open state.

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

[0048] Figure 5 is a schematic view of the uplift stress of the foundation soil in the method for determining the bearing capacity of the steel pipe screw pile of the present invention.

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

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

[0051] Description of the Reference Numerals:

[0052] 1. Pile body; 11. Steel pipe; 12. Tapered head; 2. Screw pile blade; 21. Ring blade; 22. Hinge fixing part; 3. Superimposed blade; 31. Blade; 311. Blade tail; 32. Welding plate. Detailed Embodiments

[0053] Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

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

[0055] Pile body 1;

[0056] A plurality of spiral pile blades 2 arranged around the axis of the pile body 1;

[0057] A plurality of superimposed blades 3 rotatably arranged radially along the spiral pile blade 2;

[0058] Wherein, the superimposed blade 3 contracts when the pile body 1 is screwed into the soil in the forward direction, the pile body 1 starts to reverse when it is screwed into the set depth, and the superimposed blade 3 opens and embeds into the foundation soil when the pile body 1 reverses; wherein, the uplift bearing capacity and compressive bearing capacity of the steel pipe spiral pile are determined according to the parameter data of the steel pipe spiral pile, the horizontal earth pressure of the soil around the pile after the superimposed blade 3 is unfolded, and the vertical shear force of the soil around the pile.

[0059] When the pile body 1 of the present invention is screwed into the soil in the forward direction, the superimposed blade 3 contracts, which facilitates the smooth entry of the pile body 1 into the soil. When the pile body 1 starts to reverse after being screwed into the set height, the superimposed blade 3 can open and embed into the foundation soil. Compared with the traditional method of improving the bearing capacity by simply increasing the number or area of the spiral pile blades 2, after the superimposed blade 3 of the present invention opens and embeds into the foundation soil, it can form a more effective biting and anchoring effect with the foundation soil, making use of the bearing potential of the undisturbed soil, thereby significantly improving the compressive bearing capacity and uplift bearing capacity of the steel pipe spiral pile without significantly increasing the consumption of materials, especially in soft soil foundations.

[0060] Through the design of the retractable and expandable superimposed blade 3, this solution cleverly utilizes the special working mode of the superimposed blade 3 to improve the bearing capacity, without the need to significantly increase the number and area of the spiral pile blades 2, reducing the material usage and cost.

[0061] Since the superimposed blade 3 contracts when the pile body 1 is screwed into the soil in the forward direction, the overall outer diameter of the pile body 1 is relatively small. Compared with the situation where the outer diameter of the pile body 1 increases and the screwing resistance increases due to significantly increasing the number or area of the spiral pile blades 2 in the traditional method, this solution is more conducive to the pile body 1 being screwed into the soil, reducing the difficulty of screwing the pile body 1 during the construction process. Moreover, during the construction process, there is no need for complex equipment and processes to handle a large number of blades, the operation is simple, which can improve the construction efficiency and reduce the construction time and labor cost.

[0062] The design of this steel pipe spiral pile has better adaptability to different types of foundation soils, especially soft foundation soils. Through the ingenious design of the superimposed blade 3, this solution can effectively improve the bearing performance of the pile body 1 in soft foundation soils without changing the basic structure and construction method of the pile body 1, broadening the application range of the steel pipe spiral pile.

[0063] After the superimposed blades 3 are opened and embedded in the foundation soil, the contact area and friction between the pile body 1 and the foundation soil are increased, so that the pile body 1 and the soil form a tighter combination, thereby improving the overall stability of the pile body 1. When bearing external loads, this stable structure can more effectively transfer the loads, reduce the deformation and displacement of the pile body 1, and ensure the safety of the upper structure.

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

[0065] a steel pipe 11, and a plurality of spiral pile blades 2 are arranged around the axial direction of the steel pipe 11;

[0066] a conical head 12 provided at the pipe head of the steel pipe 11.

[0067] In this example, the pile body 1 is composed of the steel pipe 11 and the conical head 12 provided at the pipe head. The steel pipe 11 has high strength and good durability, can effectively transfer loads, resist erosion, its flexibility can adapt to the deformation of the foundation, is convenient for construction, connection and recycling, and has good environmental protection. The conical head 12 has a guiding and positioning function, can reduce the resistance to entry into the soil, is conducive to the pile body 1 entering the soil vertically, reduces the construction difficulty and cost. At the same time, it enhances the interaction between the pile and the soil, improves the bearing capacity and stability, and also protects the end of the pile body 1, preventing collision deformation and internal corrosion. The two cooperate to significantly optimize the performance of the pile body 1 and provide a reliable guarantee for the engineering foundation.

[0068] As Figure 2 、 Figure 3 shown, in an alternative embodiment of the present invention, the spiral pile blade 2 includes:

[0069] an annular blade 21, the annular blade 21 is fixed on the steel pipe 11 at a set inclination, and the annular blade 21 cuts obliquely downward when the steel pipe 11 is screwed into the soil forward;

[0070] a plurality of articulated fixing members 22 provided on the annular blade 21, and the articulated fixing members 22 are rotatably connected to the superimposed blade 3.

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

[0072] Multiple hinge fixing parts 22 provided on the annular blade 21 are rotatably connected to the superimposed blade 3, providing flexible working conditions for the superimposed blade 3. During the stage of screwing the pile body 1 into the ground, the superimposed blade 3 can contract without affecting the operation of entering the soil; when the pile body 1 reaches the set height and reverses, the superimposed blade 3 can smoothly open. This design not only ensures the 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 basic frictional force and lateral bearing capacity; after the superimposed blade 3 opens, it further strengthens the pile-soil interlock. The combination of the two greatly improves the compressive and tensile bearing capacities of the pile body 1, meeting the stringent requirements of the project for the foundation stability.

[0074] As Figure 2 、 Figure 3 shown, in an optional embodiment of the present invention, the superimposed blade 3 includes:

[0075] Two upper and lower blades 31 rotatably connected to the hinge fixing part 22. When the blades 31 contract, other parts except the blade tail 311 overlap with the annular blade 21. When the blades 31 open, the blade tail 311 is driven by the soil resistance to open the blades 31.

[0076] In this example, it is composed of two upper and lower parts and when contracting, other parts except the blade tail 311 overlap with the annular blade 21. During the process of screwing the pile body 1 into the soil in the forward direction, the overall contour of the superimposed blade 3 fits the annular blade 21, making the shape of the pile body 1 relatively compact, effectively reducing the resistance to entering the soil, enabling the pile body 1 to smoothly pass through various soil layers, reducing the construction difficulty and improving the construction efficiency.

[0077] When the pile body 1 is screwed into the specified depth and reverses, when the blades 31 open, the blade tail 311 is driven by the soil resistance to open the blades 31. This ingenious design does not require additional operations and can realize the automatic unfolding of the blades 31 by using the natural resistance of the soil, saving manpower and construction time, and at the same time ensuring the accuracy and reliability of the unfolding timing of the superimposed blade 3.

[0078] After the blades 31 open, it increases the contact area and the degree of interlock between the pile body 1 and the soil, greatly improving the tensile and compressive bearing capacities of the pile body 1. Under complex geological conditions such as soft foundations, it can provide more stable support for buildings and structures, effectively reducing the risks of settlement and displacement, and ensuring the long-term stability and safety of the engineering structure.

[0079] As Figure 2 、 Figure 3As shown in the figure, in an alternative 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 contacts and fixes with the annular blade 21 when the blade 31 opens to a set degree. The blade 31 is generally in the shape of a fan blade.

[0080] In this example, a welding plate 32 is arranged between the backs of the upper and lower blades 31. When the blade 31 opens to a set degree, the welding plate 32 contacts and fixes with the annular blade 21, playing a key limiting role to ensure that the opening angle of the blade 31 is accurate and stable. This avoids the influence of the over-opening or shaking of the blade 31 on the overall performance of the pile body 1, and ensures that the superimposed blade 3 forms a stable cooperative structure with the annular blade 21 in the working state, improving the bearing capacity and stability of the pile body 1 against loads.

[0081] The blade 31 is generally in the shape of a fan blade. This shape has a larger contact area with the soil after opening and can more effectively disperse the load received by the pile body 1 evenly to the surrounding soil. Compared with the blade 31 of ordinary shape, the fan blade shape design significantly improves the uplift and compressive bearing capacity of the pile body 1, especially suitable for building projects with high requirements for foundation bearing capacity, and can effectively reduce the risks of settlement and inclination of the pile body 1.

[0082] The way that the welding plate 32 contacts and fixes with the annular blade 21 ensures that the blade 31 will not accidentally close or loosen when enduring complex loads and soil effects for a long time. Under various harsh geological conditions, it can still reliably play the role of enhancing the bearing capacity, providing a solid guarantee for the long-term stable operation of the engineering foundation.

[0083] When designing the structure of buildings and structures, it is necessary to check whether the vertical bearing capacity of the pile foundation meets the design requirements. That is, the vertical pressure received by the pile foundation should be less than the characteristic value of the vertical bearing capacity of the pile foundation, and the vertical uplift force received by the pile foundation should be less than the sum of the characteristic value of the vertical bearing capacity of the pile foundation and the self-weight of the pile foundation. During the construction process, understanding the bearing capacity of the steel pipe spiral pile can help the construction personnel reasonably select construction equipment and construction technology, and avoid construction accidents caused by insufficient bearing capacity of the pile.

[0084] The steel pipe spiral pile of the present invention has unique structures such as the annular blade 21 and the superimposed blade 3 that can be rotatably connected. Conventional methods do not consider the complex influences of the inclination of the annular blade 21, the contraction and opening of the superimposed blade 3, and the limit of the welding plate 32 on the bearing capacity. For example, it is difficult to accurately determine the improvement effect of the bearing capacity by conventional methods due to the changes in the contact area and the biting degree between the superimposed blade 3 and the soil when the superimposed blade 3 opens.

[0085] Ordinary piles mainly bear vertical pressure or tension. In addition to vertical forces, the steel pipe screw piles of the present invention also bear large torques and lateral forces during the screwing-in and loading processes due to the spiral structure. Conventional determination methods cannot accurately consider the interaction of these complex forces and their influence on bearing capacity. For example, torque can change the stress state of the soil around the pile, affecting the pile-soil friction and the overall stability of the pile.

[0086] The screwing-in construction of steel pipe screw piles will have a unique extrusion and disturbance effect on the soil around the pile, making the changes in the physical and mechanical properties of the soil around the pile different from those of conventional piles. Conventional methods are difficult to accurately consider the influence of the soil property changes caused by this special construction method on bearing capacity. For example, during construction in soft soil, the strength of the soil around the pile may be improved to a certain extent due to extrusion, which is different from the soil disturbance situation during the pile formation of conventional piles.

[0087] As Figure 4 shown, the present invention also provides a method for determining the bearing capacity of a steel pipe screw pile, which is applied to the steel pipe screw pile as described above and includes:

[0088] Step 11, obtaining the parameter data of the steel pipe screw pile inserted into the soil;

[0089] Step 12, determining the horizontal soil pressure of the soil around the pile and the vertical shear force of the soil around the pile according to the parameter data;

[0090] Step 13, determining the uplift bearing capacity and compressive bearing capacity of the steel pipe screw pile according to the parameter data of the steel pipe screw pile, the horizontal soil pressure of the soil around the pile, and the vertical shear force of the soil around the pile. According to the special structure of the steel pipe screw pile, its bearing capacity is determined by two parts, namely the undisturbed soil shear strength above the superimposed blade 3 and the residual strength of the disturbed soil above the screw pile blade 2.

[0091] Specifically, the obtaining of the parameter data of the steel pipe screw pile inserted into the soil includes:

[0092] Obtaining the soil unit weight γ of the soil into which the steel pipe screw pile is inserted, the coefficient of earth pressure at rest K0 of the soil, the internal friction angle of the undisturbed soil particles above the superimposed blade 3 The internal friction angle of the disturbed soil parameters of the soil particles above the superimposed blade 3 The cohesion c1 of the undisturbed soil particles above the superimposed blade 3, the cohesion c2 of the disturbed soil particles above the superimposed blade 3, and the depth h from the calculation position of the steel pipe screw pile inserted into the soil to the ground surface.

[0093] Among them, the part of the soil whose original structure and physical and mechanical properties are changed due to the extrusion, cutting, etc. on the soil around the pile during the insertion process of the steel pipe screw pile is called disturbed soil, and the foundation soil that remains undisturbed and maintains its natural structure and state is called undisturbed soil.

[0094] Determining the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile according to the parameter data includes:

[0095] Determining the horizontal earth pressure of the soil around the pile according to σ h =γhK0;

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

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

[0098] wherein, σ h is the horizontal earth pressure of the soil around the pile, γ is the unit weight of the soil, h is the depth of the calculation position from the ground surface, and K0 is the coefficient of earth pressure at rest, is the internal friction angle of the soil particles of the undisturbed soil above the superimposed blade 3, is the internal friction angle of the parameter soil particles of the disturbed soil above the superimposed blade 3 c1 is the cohesion of the soil particles of the undisturbed soil above the superimposed blade 3, c2 is the cohesion of the soil particles of the disturbed soil above the superimposed blade 3 (c1>c2), τ1 is the shear force of the undisturbed soil, and τ2 is the shear force of the disturbed soil.

[0099] As shown in Figure 5 and Figure 6 , determining the uplift bearing capacity of the steel pipe screw pile according to the parameter data of the steel pipe screw pile, the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile includes:

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

[0101] Obtaining the characteristic value of the vertical uplift bearing capacity of a single pile according to ;

[0102] wherein, T uk is the standard value of the ultimate vertical uplift bearing capacity of a single pile, γ is the unit weight of the soil, l is the depth of the lowest blade of the steel pipe screw pile from the ground surface, is the internal friction angle of the soil particles of the undisturbed soil above the superimposed blade 3, is the internal friction angle of the parameter soil particles of the disturbed soil above the superimposed blade 3 c1 is the cohesion of the soil particles of the undisturbed soil above the superimposed blade 3, c2 is the cohesion of the soil particles of the disturbed soil above the superimposed blade 3 (c1>c2), μ1 is the total vertical projected perimeter of the superimposed blade 3, μ2 is the vertical projected perimeter of the screw pile blade 2 minus the overlapping part with the superimposed blade 3, and R a is the characteristic value of the vertical uplift bearing capacity of a single pile.

[0103] Specifically, the horizontal earth pressure σ of the soil around the steel pipe screw pile h = γhK0, and the vertical shear force of the soil around the steel pipe screw pile Differentiate to take dh for the vertical direction of the ring pile in one week Integrate the calculation position depth h from the ground surface to the depth l of the lowest blade, and calculate and superimpose the bearing capacity of the undisturbed soil above blade 3 and the bearing capacity of the disturbed soil above the screw pile blade 2 respectively:

[0104]

[0105] Substitute the strength parameters of the undisturbed soil and the disturbed soil to obtain the standard value of the ultimate uplift bearing capacity of the pile:

[0106]

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

[0108] Among them, when determining the horizontal earth pressure and vertical shear force of the soil around the pile, multiple parameters such as soil unit weight, coefficient of earth pressure at rest, internal friction angle and cohesion of soil particles in different states (undisturbed soil and disturbed soil), and the depth of the calculation position from the ground surface are fully considered. The shear force is calculated separately for the undisturbed soil and the disturbed soil, and when determining the uplift bearing capacity, the different mechanical properties of the undisturbed soil above blade 3 and the disturbed soil above the screw pile blade 2 are distinguished, making the calculation model closer to the actual situation, thereby improving the accuracy of the description of the mechanical properties of the soil around the pile, and further enhancing the accuracy of the calculation of the uplift bearing capacity of the steel pipe screw pile. This can more accurately reflect the interaction between the steel pipe screw pile and the soil under the actual working conditions, providing a more reliable basis for engineering design.

[0109] Adopt the method of differentiating to take dh for the vertical direction of the ring pile in one week and integrating the calculation position depth h from the ground surface to the depth l of the lowest blade, and calculate and superimpose the bearing capacity of the undisturbed soil above blade 3 and the bearing capacity of the disturbed soil above the screw pile blade 2 respectively. This analysis method based on calculus and soil mechanics principles comprehensively and deeply considers the interaction mechanism between the pile and the soil from a theoretical level, carefully analyzes and integrates the forces acting on the pile body, ensures the scientificity and rationality of the determination method, and makes the determination process of the bearing capacity have a solid theoretical foundation.

[0110] This method can adapt to different soil conditions (such as soils with different unit weights, internal friction angles, and cohesion) and different working states (uplift conditions) of steel pipe screw piles. By substituting the corresponding actual parameters, the uplift bearing capacity of steel pipe screw piles can be accurately determined under various complex and changeable engineering environments. It can provide relatively accurate calculation results whether in areas with simple or complex geological conditions, has strong applicability, expands the application scope of this method, and meets the needs of different projects for calculating the bearing capacity of steel pipe screw piles.

[0111] The characteristic value of the vertical uplift bearing capacity of a single pile is obtained by dividing the standard value of the vertical uplift ultimate bearing capacity of a single pile by a safety factor. Generally, the value of this safety factor is around 2. This is done to ensure that in actual projects, when the pile bears the load specified in the design, there is sufficient safety margin to ensure the sufficient stability and reliability of the pile foundation.

[0112] The bearing capacity calculation closely focuses on the unique structure of the steel pipe screw pile with superimposed blades 3, and introduces parameters related to the pile body structure such as the total vertical projection perimeter of the superimposed blade 3 and the vertical projection perimeter of the screw pile blade 2 minus the overlapping part with the superimposed blade 3. The introduction of these parameters enables the calculation method to better reflect the mechanical characteristics of this special pile type, more accurately reflect the interaction relationship between the pile body structure and the soil, and thus provide a more targeted basis for the structural optimization design of steel pipe screw piles.

[0113] Such as Figure 6 、 Figure 7 As shown, according to the parameter data of the steel pipe screw pile, the horizontal earth pressure of the soil 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 screw pile is determined, including:

[0114] According to Obtain the standard value of the vertical compressive ultimate bearing capacity of a single pile;

[0115] According to Obtain the characteristic value of the vertical compressive bearing capacity of a single pile;

[0116] Among them, Q uk is the standard value of the vertical compressive ultimate bearing capacity of a single pile, γ is the unit weight of the soil, l is the depth of the lowest blade of the steel pipe screw pile from the ground surface, is the internal friction angle of the original soil particles above the superimposed blade 3, is the internal friction angle of the disturbed soil parameter soil particles above the superimposed blade 3 c1 is the cohesion of the original soil particles above the superimposed blade 3, c2 is the cohesion of the disturbed soil particles above the superimposed blade 3 (c1 > c2), μ1 is the total vertical projected perimeter of the superimposed blade 3, μ2 is the vertical projected perimeter of the helical pile blade 2 minus the overlapping part with the superimposed blade 3, q pk is the standard value of the ultimate end resistance of the pile tip soil, A D is the projected area of the helical pile blade 2, R b is the characteristic value of the vertical compressive bearing capacity of a single pile.

[0117] Specifically, the horizontal earth pressure σ h around the steel pipe helical pile = γhK0, and the vertical shear force of the steel pipe helical pile for a differential dh around the pile in the vertical direction Integrating the calculation position depth h from the ground surface to the depth l of the lowest blade to obtain the compressive bearing capacity of the pile side:

[0118]

[0119] Substitute the strength parameters of the undisturbed soil and the disturbed soil, calculate 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 respectively, and then sum them with the pile tip bearing capacity to finally obtain the standard value of the overall compressive ultimate bearing capacity of a single pile:

[0120]

[0121] The characteristic value of the vertical compressive bearing capacity of a single pile

[0122] Among them, this method comprehensively considers many parameter data of the steel pipe helical pile, such as the soil unit weight, the depth of the lowest blade of the steel pipe helical pile from the ground surface, the relevant parameters of the superimposed blade 3 and the helical pile blade 2, as well as the horizontal earth pressure and vertical shear force of the soil around the pile. By distinguishing 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 and other parameters respectively, it can more accurately reflect the complex interaction relationship between the steel pipe helical pile and the surrounding soil when under compression, making the calculation results more in line with the actual stress situation and providing a reliable basis for engineering design.

[0123] Using the method of taking a differential dh around the pile in the vertical direction and integrating the calculation position depth h from the ground surface to the depth l of the lowest blade to calculate the compressive bearing capacity of the pile side, this analysis method based on calculus and soil mechanics principles comprehensively and deeply considers the contribution of the mechanical properties of the soil at different positions of the pile body to the compressive bearing capacity of the pile side, ensuring the scientificity and rationality of this method at the theoretical level and making the determination process of the compressive bearing capacity have a solid theoretical foundation.

[0124] This method can adapt to different soil conditions (soils with different unit weights, internal friction angles, and cohesion) and the actual working conditions of steel pipe screw piles. For different engineering sites, only by substituting the corresponding actual parameters, the compressive bearing capacity of steel pipe screw piles under various complex geological environments can be accurately determined. Whether in soft soil foundation or hard soil foundation, relatively accurate calculation results can be provided, with strong applicability, expanding the application scope of this method and meeting the needs of different projects for calculating the compressive bearing capacity of steel pipe screw piles.

[0125] When calculating the standard value of the ultimate vertical compressive bearing capacity of a single pile, not only the compressive bearing capacity of the pile side (including the contributions of undisturbed soil and disturbed soil) is considered, but also the important factor of the standard value of the ultimate end resistance of the pile tip soil is incorporated. Considering the bearing capacities of the pile body and the pile tip in this comprehensive way can more accurately evaluate the overall compressive performance of steel pipe screw piles, avoiding the situation of only focusing on the side resistance of the pile and ignoring the influence of the end resistance on the bearing capacity, making the evaluation 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, there are many uncertain factors such as the possible non-uniformity of soil properties and the variation of loads. Therefore, in order to ensure the safety of the pile foundation during actual use, a safety factor needs to be introduced. Divide the standard value of the ultimate vertical compressive bearing capacity of a single pile by the safety factor to obtain the characteristic value of the vertical compressive bearing capacity of a single pile. The value of the safety factor is not fixed and will be determined according to factors such as the importance of the project and the complexity of the geological conditions. Generally, it is about 2.

[0127] This method closely combines the special structure of steel pipe screw piles (such as the superimposed blade 3 and the screw pile blade 2, etc.) to calculate the compressive bearing capacity, and introduces key parameters related to the pile body structure. These parameters can accurately reflect the influence of the pile body structure on its compressive performance, providing detailed and accurate basis for the structural optimization design of steel pipe screw piles. Engineers can adjust and improve the pile body structure according to the calculation results to further improve the compressive bearing capacity and overall performance of steel pipe screw piles, reduce project costs, and improve project benefits.

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

[0129] Based on the principles of calculus and soil mechanics, using the method of taking infinitesimals by differentiation and then integrating, comprehensively and deeply considering the pile-soil interaction mechanism, and carefully analyzing and integrating the forces on the pile body, ensuring the scientificity and rationality of the determination method, and making the bearing capacity determination process have a solid theoretical support.

[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 screw piles (tensile resistance, compressive resistance). By substituting actual parameters, the bearing capacity can be accurately determined in various complex engineering environments. Whether in simple or complex geological regions, relatively accurate calculation results can be provided to meet the requirements of different projects for bearing capacity calculation.

[0131] When determining the characteristic values of the vertical tensile and compressive bearing capacities of a single pile, a safety factor (generally about 2) is introduced to consider uncertain factors such as uneven soil properties and load fluctuations in actual projects, leaving sufficient safety margins 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 the compressive bearing capacity of the pile side (including the contributions of undisturbed soil and disturbed soil) is considered, but also the standard value of the ultimate end resistance of the pile tip soil is incorporated to comprehensively evaluate the overall compressive performance of the steel pipe screw pile, avoiding neglecting the influence of the pile tip resistance and making the evaluation results more reliable and comprehensive.

[0133] The bearing capacity is calculated closely in combination with the special structure of the steel pipe screw pile (such as the superimposed blade 3 and the screw pile blade 2, etc.), and key parameters related to the pile body structure are introduced to accurately reflect the influence of the structure on the compressive and tensile performances, providing a detailed and accurate basis for the optimal design of the pile body structure. Engineers can adjust and improve the pile body structure accordingly to enhance the bearing capacity and overall performance, reduce engineering costs, and improve engineering benefits.

[0134] Example 1

[0135] For a photovoltaic project in a certain place, according to the geotechnical engineering investigation report, the unit weight of the foundation sand soil is 18 kN / m 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 distance from the lowest superimposed blade 3 to the ground surface is 2.5 m, the penetration depth of the pile foundation is 2.6 m, the standard value of the ultimate side resistance of the foundation sand soil q sk is 18 kPa, the total projected perimeter of the superimposed blade 3 is 1.2 m, the vertical projected perimeter of the screw 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, and the projected area of the screw pile blade 2 is 0.04 m2.

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

[0137]

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

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

[0140]

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

[0142] The determination method of this bearing capacity is based on the unique structural characteristics of this pile type. By introducing parameters such as the total perimeter of the vertical projection of the superimposed blade 3, it can more accurately reflect the interaction between the pile body 1 and the soil, thus more accurately determining the bearing capacity. It fully considers various characteristics of the soil, such as unit weight, earth pressure at rest, internal friction angle, cohesion, and standard value of ultimate end resistance of pile tip soil, etc. These parameters can comprehensively reflect the mechanical properties of the soil under different geological conditions, making the determination result more in line with the actual engineering situation and applicable to various complex geological environments. Accurately determining the characteristic value of vertical uplift bearing capacity of single pile and the characteristic value of vertical compressive bearing capacity of single pile can provide a reliable basis for engineering design.

[0143] It should be noted that this method corresponds to the above steel pipe spiral pile. All implementation manners in the above embodiments of the steel pipe spiral pile are applicable to the embodiments of this method and can also achieve the same technical effects.

[0144] The above is the preferred implementation manner of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A steel pipe screw pile, characterized in that, Comprising: A pile body (1); A plurality of spiral pile blades (2) arranged around the axis of the pile body (1); A plurality of superimposed blades (3) rotatably arranged radially along the spiral pile blades (2); Wherein, the superimposed blades (3) contract when the pile body (1) is screwed into the soil in the forward direction, the pile body (1) starts to reverse when it is screwed into a set depth, and the superimposed blades (3) open and embed into the foundation soil when the pile body (1) reverses; wherein, the uplift bearing capacity and compressive bearing capacity of the steel pipe spiral pile are determined according to the parameter data of the steel pipe spiral pile, the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile.

2. The steel pipe screw pile according to claim 1, wherein The pile body (1) comprises: A steel pipe (11), and a plurality of spiral pile blades (2) are arranged around the axis of the steel pipe (11); A conical head (12) provided at the pipe head of the steel pipe (11).

3. The steel pipe screw pile according to claim 2, characterized in that, The spiral pile blade (2) comprises: An annular blade (21), the annular blade (21) is fixed on the steel pipe (11) at a set inclination, and the annular blade (21) cuts obliquely downward when the steel pipe (11) is screwed into the soil in the forward direction; A plurality of articulated fixing members (22) provided on the annular blade (21), and the articulated fixing members (22) are rotatably connected to the superimposed blades (3).

4. The steel pipe screw pile according to claim 3, wherein, The superimposed blade (3) comprises: Two upper and lower blades (31) rotatably connected to the articulated fixing member (22), when the blades (31) contract, other parts except the blade tails (311) overlap with the annular blade (21), and when the blades (31) open, the blade tails (311) are driven by the soil resistance to drive the blades (31) to open.

5. The steel pipe screw pile according to claim 4, characterized in that, A welding plate (32) is provided between the backs of the two upper and lower blades (31), and the welding plate (32) contacts and fixes with the annular blade (21) when the blades (31) open to a set degree, and the blades (31) are integrally in the shape of a fan blade.

6. A method for determining the bearing capacity of a steel pipe screw pile, which is applied to the steel pipe screw pile according to any one of claims 1 to 5, characterized in that, Comprising: Obtaining the parameter data of the steel pipe spiral pile inserted into the soil; Determining the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile according to the parameter data; Determining the uplift bearing capacity and compressive bearing capacity of the steel pipe spiral pile according to the parameter data of the steel pipe spiral pile, the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile.

7. The method for determining the bearing capacity of the steel pipe screw pile according to claim 6, characterized in that, The obtaining the parameter data of the steel pipe spiral pile inserted into the soil includes: Obtain the soil unit weight γ of the steel pipe screw pile inserted into the soil, the coefficient of earth pressure at rest K0 of the soil, and the internal friction angle of the original soil particles above the superimposed blade (3). The internal friction angle of the disturbed soil parameters of the soil particles above the superimposed blade (3). The cohesion c1 of the original soil particles above the superimposed blade (3), the cohesion c2 of the disturbed soil particles above the superimposed blade (3), and the depth h from the ground surface to the calculation position of the steel pipe screw pile inserted into the soil.

8. The method for determining the bearing capacity of the steel pipe spiral pile according to claim 7, characterized in that The determining the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile according to the parameter data includes: According to σ h Determine the horizontal earth pressure of the soil around the pile according to σ = γhK0; According to Determine the shear force of undisturbed soil; According to Determine the shear force of disturbed soil; Among them, σ h is the horizontal earth pressure of the soil around the pile, γ is the unit weight of the soil, h is the depth from the calculation position to the ground surface, and K0 is the coefficient of earth pressure at rest. is the internal friction angle of the original soil particles above the superimposed blade (3), is the internal friction angle of the disturbed soil particles above the superimposed blade (3), c1 is the cohesion of the original soil particles above the superimposed blade (3), and c2 is the cohesion of the disturbed soil particles above the superimposed blade (3). τ1 is the shear force of the original soil, and τ2 is the shear force of the disturbed soil.

9. The method for determining the bearing capacity of the steel pipe screw pile according to claim 8, characterized in that, The determining the uplift bearing capacity of the steel pipe spiral pile according to the parameter data of the steel pipe spiral pile, the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile includes: According to the standard value of the ultimate vertical uplift bearing capacity of a single pile is obtained; According to obtain the characteristic value of the vertical uplift bearing capacity of a single pile; Among them, T uk is the standard value of the ultimate vertical uplift bearing capacity of a single pile, γ is the unit weight of the soil, l is the depth from the lowest blade of the steel pipe screw pile to the ground surface, is the internal friction angle of the original soil particles above the superimposed blade (3), is the internal friction angle of the disturbed soil parameter particles above the superimposed blade (3), c1 is the cohesion of the original soil particles above the superimposed blade (3), and c2 is the cohesion of the disturbed soil particles above the superimposed blade (3). μ1 is the total vertical projection perimeter of the superimposed blade (3), μ2 is the vertical projection perimeter of the screw pile blade (2) minus the overlapping part with the superimposed blade (3), R a is the characteristic value of the vertical uplift bearing capacity of a single pile.

10. The method for determining the bearing capacity of the steel pipe screw pile according to claim 9, characterized in that, The determining the characteristic value of the compressive bearing capacity of the steel pipe spiral pile according to the parameter data of the steel pipe spiral pile, the horizontal earth pressure of the soil around the pile and the vertical shear force of the soil around the pile includes: According to obtain the standard value of the ultimate vertical compressive bearing capacity of a single pile; According to the characteristic value of the vertical compressive bearing capacity of a single pile is obtained; Among them, Q uk is the standard value of the ultimate vertical compressive bearing capacity of a single pile, γ is the unit weight of the soil, l is the depth of the lowest blade of the steel pipe screw pile from the ground surface, is the internal friction angle of the original soil particles above the superimposed blade (3), is the internal friction angle of the disturbed soil parameter particles above the superimposed blade (3), c1 is the cohesion of the original soil particles above the superimposed blade (3), c2 is the cohesion of the disturbed soil particles above the superimposed blade (3), μ1 is the total vertical projection perimeter of the superimposed blade (3), μ2 is the vertical projection perimeter of the screw pile blade (2) minus the overlapping part with the superimposed blade (3), q pk is the standard value of the ultimate tip resistance of the pile tip soil, A D is the projected area of the screw pile blade (2), R b is the characteristic value of the vertical compressive bearing capacity of a single pile.

Images