Soft soil lower pile foundation monitorable embedding and fixing anti-scouring integrated device

Abstract

The invention discloses a monitorable embedding and anti-scour integrated device for a pile foundation under soft soil. The monitorable embedding and anti-scour integrated device comprises an anti-scour nesting unit, a wedge-shaped damage area auxiliary unit, a full-flow damage area auxiliary unit, a rotary damage area auxiliary unit and a bedrock embedding unit which are sequentially arranged on the outer wall of a fan single pile in a sleeving mode from top to bottom. The bedrock build-in unit is pre-buried at the bottom of a fan single pile and is sequentially connected with the rotary failure area auxiliary unit, the full-flow failure area auxiliary unit and the wedge-shaped failure area auxiliary unit through longitudinal beams; a horizontal spring is connected between the wedge-shaped damage area auxiliary unit and the outer wall of the fan single pile, and tension is preset by the horizontal spring; the full-flow failure area auxiliary unit is connected with the outer wall of the fan single pile through a longitudinal cable-stayed spring, and tension is preset by the longitudinal cable-stayed spring; the rotary damage area auxiliary unit is connected with the bottom of the fan single pile through a vertical spring, and the vertical spring presets tension; each spring module is provided with an elastic force sensor and a magnetic encoder which are used for monitoring the state of the fan single pile in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore wind power devices, and in particular relates to a monitorable, embedded and anti-scour integrated device for pile foundations in soft soil. Background Art

[0002] As the global energy mix shifts toward cleaner, low-carbon energy, the offshore wind power industry, with its abundant resources and high power generation efficiency, has become a key area of renewable energy development. However, the widespread soft sandy soils in offshore waters pose significant challenges to the deployment of traditional monopile-fixed wind turbine foundations.

[0003] With the gradual development of high-quality offshore wind farm resources, wind power construction is extending into the mid- and far-sea transition zone, with water depths of 15-50 meters. The widespread Quaternary sedimentary layers in this region (such as the soft clays of the East China Sea shelf, the calcareous sands of the South China Sea, and the silty sands of the North Sea) exhibit significant foundation suitability issues. These layers have natural moisture contents as high as 30%-50%, standard penetration numbers (SPT-N values) generally below 15, and undrained shear strengths (Su) below 30 kPa, far below the required bearing capacity threshold of over 150 kPa for fixed wind turbine foundations. While monopile foundations have become the mainstream solution due to their simple structure and ease of construction, these soft sand beds, subject to complex marine loads (such as extreme typhoon waves, tidal currents, and ship impacts), lack of embedment depth and insufficient lateral restraint in these soft sand beds can increase the risk of pile overturning, lead to abnormal dynamic responses (such as resonant frequency shifts), and shorten service life. The presence of this weak foundation hinders the physicalization and scale-up of fixed wind turbines in mid-sea and offshore installations. The lack of appropriate equipment hinders the deployment of single-pile fixed wind turbines in such subsoil environments. Piles are typically classified based on their stiffness relative to the surrounding soil and their deformation characteristics under load, involving factors such as aspect ratio, elastic modulus of the pile material, and soil properties. The interaction between rigid-flexible piles and soil is the most complex, and further research is needed to address the embedding issues of rigid-flexible pile offshore fixed wind turbines in soft soils. Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a new type of fixed pile foundation for offshore wind turbines, which is to provide a new type of fixed pile foundation for offshore wind turbines, in order to solve the problem that when a single pile of an offshore fixed wind turbine is embedded in soft foundation sand, the soft sand cannot exert sufficient foundation soil reaction force on the pile foundation due to its own characteristics, resulting in the pile foundation being unable to be reasonably embedded.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A monitorable, embedded, and anti-scour integrated device for pile foundations in soft soils, comprising an anti-scour nesting unit, a wedge-shaped failure zone auxiliary unit, a full-flow failure zone auxiliary unit, a rotational failure zone auxiliary unit, and a bedrock embedding unit, which are sequentially sleeved on the outer wall of a wind turbine pile from top to bottom.

[0007] The bedrock embedded unit is pre-buried at the bottom of the wind turbine pile and is sequentially connected to the rotational destruction zone auxiliary unit, full flow destruction zone auxiliary unit, and wedge-shaped destruction zone auxiliary unit above it through a set of longitudinal beams;

[0008] A group of horizontal springs are connected between the wedge-shaped destruction zone auxiliary unit and the outer wall of the fan single pile, and the horizontal springs have a preset tension; the full-flow destruction zone auxiliary unit is connected to the outer wall of the fan single pile through a group of longitudinal inclined springs, and the longitudinal inclined springs have a preset tension; the rotational destruction zone auxiliary unit is connected to the bottom of the fan single pile through a vertical spring, and the vertical spring has a preset tension; each spring module is respectively provided with an elastic force sensor and a magnetic encoder for real-time monitoring of the status of the fan single pile.

[0009] Specifically, the anti-scour nested unit includes an annular sleeve and a diversion pile barrel; the annular sleeve is fixed on the outer wall of the wind turbine single pile by interference fit; the diversion pile barrel is sleeved on the outside of the wind turbine single pile and is located below the annular sleeve, and the bottom of the diversion pile barrel is connected to the cylindrical load-bearing device of the wedge-shaped destruction zone auxiliary unit; the outer wall of the diversion pile barrel is provided with a diversion groove along the water scouring direction.

[0010] Specifically, the wedge-shaped destruction zone auxiliary unit includes a group of cylindrical load-bearing devices; the cylindrical load-bearing devices are connected in sequence from top to bottom through a group of longitudinal longitudinal beams, so as to be mounted on the periphery of the wind turbine single pile; the inner wall of each cylindrical load-bearing device is connected to the outer wall of the wind turbine single pile through a group of horizontal springs; the horizontal springs are distributed at equal intervals in the annular direction; the outer wall of the wind turbine single pile is provided with a square load-bearing plate corresponding to each horizontal spring.

[0011] Specifically, there are more than two cylindrical load-bearing devices, which are buried in the soft soil area along the longitudinal direction of the wind turbine pile, and the bottom cylindrical load-bearing device is set at the bottom position of the wind turbine pile.

[0012] Specifically, the full-flow destruction zone auxiliary unit includes an oblique spring load-bearing cylinder and a group of longitudinal oblique tension springs; the oblique spring load-bearing cylinder is arranged in the middle and lower part of the wind turbine single pile, and one end of the longitudinal oblique tension spring is fixed on the top outer wall of the wind turbine single pile, and the other end is fixed on the oblique spring load-bearing cylinder, and each longitudinal oblique tension spring is evenly arranged in the ring direction; a group of oblique spring load-bearing plates for fixing the longitudinal oblique tension springs are provided on the inner wall of the oblique spring load-bearing cylinder.

[0013] Specifically, the rotational destruction zone auxiliary unit includes a vertical spring and a horizontal load-bearing beam; one end of the horizontal load-bearing beam is fixed to the inner side of the longitudinal beam, and the other end extends horizontally to the bottom of the wind turbine pile, and is connected and tightened with the bottom of the wind turbine pile through a vertical spring.

[0014] Specifically, the bedrock embedded unit includes a group of tubular pile foundations and a group of longitudinal beams cast in the rock layer or hard soil area; the top of the tubular pile foundation is connected to the upper rotational destruction zone auxiliary unit, full flow destruction zone auxiliary unit, and wedge-shaped destruction zone auxiliary unit through the longitudinal beams.

[0015] Furthermore, the horizontal spring tension In the case of soft clay foundation, the following formula is satisfied:

[0016]

[0017] Where y represents the lateral displacement, y c Expressed as the critical lateral displacement, Expressed as the spring unit stiffness coefficient, Expressed as the change in the advance and contraction amount of the spring unit; is the design value of horizontal foundation soil reaction;

[0018] is the ultimate soil resistance, =γ′z1⋅D⋅Kp;

[0019] Where, γ′ is the effective bulk density;

[0020] D is the pile diameter;

[0021] Kp is the passive earth pressure coefficient;

[0022] z1 is the burial depth;

[0023] The horizontal spring tension In the case of sandy soil foundation, the following formula must be satisfied:

[0024]

[0025] If the deformation of the soft sand around the pile foundation is allowed to enter the nonlinear stage within a certain range and the displacement limit and fatigue life requirements are still required to be met, the setting of the auxiliary device does not need to be conservative. In this case, the horizontal spring tension The following formula must be satisfied:

[0026]

[0027] Where, k is the initial stiffness, k=E soil / D;E soilis the sand modulus; y represents the lateral displacement; D is the pile diameter;

[0028] is the effective vertical stress, , is the total vertical stress, u is the pore water pressure; Expressed as the horizontal spring unit stiffness coefficient, Expressed as the change in the advance and contraction of the horizontal spring unit; is the design value of horizontal foundation soil reaction; A is the empirical coefficient, A=3.0−0.8(z1 / D).

[0029] Furthermore, the tension of the longitudinal inclined spring Satisfies the following formula:

[0030] In the case of soft clay foundation,

[0031]

[0032]

[0033] Among them, T is the side friction resistance on site, T max is the limiting lateral friction;

[0034] represents the adhesion coefficient; S u is the undrained shear strength, A s is the pile side surface area;

[0035] z2 is the lateral displacement, z 50 =0.02⋅D, D is the pile diameter;

[0036] Expressed as the stiffness coefficient of the longitudinal inclined spring unit;

[0037] Expressed as the change in the advance and contraction amount of the longitudinal inclined spring unit;

[0038] is the angle between the longitudinal inclined spring and the vertical direction;

[0039] T s It represents the designed pile side friction resistance;

[0040] In the case of sandy soil,

[0041]

[0042]

[0043]

[0044] Among them, T is the side friction resistance on site, T max is the limiting lateral friction;

[0045] is the vertical effective stress, δ is the friction angle of the pile-soil interface, δ = 0.5ϕ ∼ 0.8ϕ, ϕ is the internal friction angle of the soft soil;

[0046] is the pile side surface area;

[0047] is the dimensionless shear stiffness coefficient, usually taken as 1000∼2000;

[0048] k is the stiffness coefficient of sand;

[0049] z2 is the lateral displacement;

[0050] is the angle between the longitudinal inclined spring and the vertical direction;

[0051] Expressed as the stiffness coefficient of the longitudinal inclined spring unit, Expressed as the change in the longitudinal inclined spring unit's advance and contraction amount, T S It represents the design pile side friction.

[0052] Furthermore, the vertical spring tension Q must satisfy the following formula:

[0053] In the case of soft clay foundation,

[0054]

[0055]

[0056] In the case of sandy soil,

[0057]

[0058]

[0059] Among them, Q is the field end resistance, Q max is the ultimate end resistance;

[0060] is the effective vertical stress at the pile tip, Su is the undrained shear strength, is the pile tip area, z3 is the vertical displacement of a single pile, z 50 =0.02⋅D, Expressed as the vertical spring unit stiffness coefficient, Expressed as the change in the vertical spring unit's advance and contraction, N q 、N γ is the bearing capacity coefficient, Effective bulk density of soil It is expressed as the change in the spring unit's advance and contraction amount, and Qs represents the designed pile end resistance;

[0061]

[0062]

[0063] Φ is the internal friction angle of soft soil.

[0064] Beneficial effects:

[0065] (1) The present invention's integrated device for monitoring and embedding pile foundations in soft soils provides a possibility for deploying rigid-flexible single-pile fixed wind turbines in soft soil layers during deep-sea transitions. The device has a wide range of applicability, encompassing two common types of seabed soils and can be applied to complex soils such as layered soils. Only minor adjustments to the device layout are required, determined according to the corresponding formula.

[0066] (2) The semi-hollow design of the device of the present invention enables the existing soil to fully contact the pile foundation and reasonably bear part of the load applied by the pile foundation.

[0067] (3) Based on the study of the interaction between rigid-flexible piles and soil, the present invention grasps the main changing factors in different failure sections, flexibly adopts the applicable spring unit arrangement mode, and takes targeted measures to reduce design redundancy and lower material costs.

[0068] (4) The present invention arranges different devices in different areas according to the deformation and failure characteristics of the rigid-flexible pile soil, and performs reasonable reinforcement, which is very friendly to the later pile body monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0070] Figure 1 It is a schematic diagram of the overall structure of the integrated device of the present invention.

[0071] Figure 2 It is a schematic diagram of the buried effect of the integrated device of the present invention.

[0072] Figure 3 It is an enlarged view of the local structure of the anti-scour nested unit in the device of the present invention.

[0073] Figure 4 It is an enlarged view of the local structure of the wedge-shaped destruction zone auxiliary unit in the device of the present invention.

[0074] Figure 5It is an enlarged view of the local structure of the auxiliary unit of the full flow destruction zone in the device of the present invention.

[0075] Figure 6 It is an enlarged view of the local structure of the auxiliary unit of the rotational destruction zone in the device of the present invention.

[0076] Figure 7 It is a diagram of the pile-soil failure mode with different properties according to the present invention.

[0077] Wherein, each reference numeral represents:

[0078] 1. Anti-scour nested unit; 1-1. Diversion pile cylinder; 1-2. Annular sleeve; 2. Wedge-shaped failure zone auxiliary unit; 2-1. Horizontal spring; 2-2. Cylindrical load-bearing device; 2-3. Square load-bearing plate; 3. Full-flow failure zone auxiliary unit; 3-1. Longitudinal diagonal spring; 3-2. Oblique spring load-bearing cylinder; 3-3. Oblique spring load-bearing plate; 4. Rotational failure zone auxiliary unit; 4-1. Vertical spring; 4-2. Horizontal load-bearing beam; 5. Bedrock embedded unit; 5-1. Cylindrical pile foundation; 5-2. Longitudinal beam; 6. Wind turbine pile. DETAILED DESCRIPTION

[0079] The present invention can be better understood with reference to the following examples.

[0080] like Figure 1 and Figure 2 As shown, the pile foundation under soft soil of the present invention can be monitored and embedded in an integrated anti-scour device, including an anti-scour nested unit 1, a wedge-shaped destruction zone auxiliary unit 2, a full flow destruction zone auxiliary unit 3 and a rotational destruction zone auxiliary unit 4, and a bedrock embedded unit 5, which are sequentially arranged on the outer wall of a wind turbine pile 6 from top to bottom.

[0081] The bedrock embedded unit 5 is pre-buried at the bottom of the wind turbine pile 6 and is sequentially connected to the upper rotational destruction zone auxiliary unit 4, the full flow destruction zone auxiliary unit 3 and the wedge-shaped destruction zone auxiliary unit 2 through a set of longitudinal beams 52.

[0082] A group of horizontal springs 2-1 are connected between the wedge-shaped destruction zone auxiliary unit 2 and the outer wall of the fan pile 6, and the horizontal springs 2-1 have a preset tension; the full-flow destruction zone auxiliary unit 3 is connected to the outer wall of the fan pile 6 through a group of longitudinal inclined springs 3-1, and the longitudinal inclined springs 3-1 have a preset tension; the rotational destruction zone auxiliary unit 4 is connected to the bottom of the fan pile 6 through a vertical spring 4-1, and the vertical spring 4-1 has a preset tension; each spring module is respectively provided with an elastic force sensor and a magnetic encoder for real-time monitoring of the status of the fan pile 6.

[0083] Combine Figure 3As shown, the inner diameter of the anti-scour nested unit 1 needs to be determined in accordance with the diameter of the single pile to meet the interference fit design. The anti-scour nested unit 1 includes an annular sleeve 1-2 and a diversion pile barrel 1-1; the annular sleeve 1-2 is fixed to the outer wall of the wind turbine single pile 6 by an interference fit; the diversion pile barrel 1-1 is sleeved on the outside of the wind turbine single pile 6 and located below the annular sleeve 1-2, and the bottom of the diversion pile barrel 1-1 is connected to the cylindrical load-bearing device 2-2 of the wedge-shaped damage zone auxiliary unit 2; the outer wall of the diversion pile barrel 1-1 is provided with two sets of diversion grooves 1-3 in the front and rear along the direction of water scouring. The two sets of diversion grooves 1-3 in the front and rear form a closed loop, changing the direction of the water flow at the pile foundation where the mud surface is directly impacted, and guiding it to both sides of the pile. This method can significantly reduce the depth of pile foundation scouring. When using, the technical combination can be selected according to the specific environment. A combined solution of solidified soil + diversion plate can be adopted to take into account both anti-scouring and long-term stability.

[0084] The "three-region distribution" of the flexible pile-soil failure mode reflects the failure characteristics of the soil around the pile at different depths and stress conditions, from wedge-shaped failure in the upper part to full flow failure in the middle part, and then to rotational shear failure in the deep layer. The division of these regions helps to more accurately describe the failure mechanism of flexible piles under horizontal loads.

[0085] In the flexible pile-soil interaction, the soil around the pile exhibits a wedge-shaped failure mode under the action of horizontal loads. This failure mainly occurs in the upper area of the soil around the pile, and is characterized by uneven stress on the soil around the pile, which manifests as horizontal displacement and shear deformation. Therefore, in the upper wedge-shaped failure zone, the lateral soil resistance is the dominant factor in the embedded pile foundation. Figure 4 As shown, the present invention comprises a set of cylindrical load-bearing devices 2-2 within the wedge-shaped failure zone auxiliary unit 2. These cylindrical load-bearing devices 2-2 are connected sequentially from top to bottom via a set of longitudinal beams 5-2, thereby being fitted around the periphery of the wind turbine monopile 6. The inner wall of each cylindrical load-bearing device 2-2 is connected to the outer wall of the wind turbine monopile 6 via a set of horizontal springs 2-1. These horizontal springs 2-1 are equidistantly spaced around the circumference. A square load-bearing plate 2-3 is provided on the outer wall of the wind turbine monopile 6, corresponding to each horizontal spring 2-1. Horizontal displacement and shear deformation are reduced by the horizontal reaction force and lateral friction of the springs.

[0086] There are more than two cylindrical load-bearing devices 2 - 2 , which are buried in the soft soil area along the longitudinal direction of the wind turbine pile 6 , and the bottom cylindrical load-bearing device 2 - 2 is set at the bottom position of the wind turbine pile 6 .

[0087] The soil around the pile exhibits a full flow failure mode in the deep layer, flowing around the pile. This failure mode mainly occurs in the middle to lower areas of the pile, and is manifested as continuous deformation and slippage of the soil around the pile, usually accompanied by horizontal displacement and rotation of the pile body. That is, for the middle full flow failure zone, the pile side friction is the dominant factor in the embedded pile foundation. For this reason, combined with Figure 5The full flow destruction zone auxiliary unit 3 of the present invention includes an oblique spring bearing cylinder 3-2 and a group of longitudinal oblique tension springs 3-1; the oblique spring bearing cylinder 3-2 is arranged in the middle and lower part of the fan single pile 6, and one end of the longitudinal oblique tension spring 3-1 is fixed on the top outer wall of the fan single pile 6, and the other end is fixed on the oblique spring bearing cylinder 3-2, and each longitudinal oblique tension spring 3-1 is evenly distributed in the ring direction; a group of oblique spring bearing plates 3-3 for fixing the longitudinal oblique tension springs 3-1 are arranged on the inner wall of the oblique spring bearing cylinder 3-2.

[0088] In the deep layer of the pile, especially when the pile stiffness is further reduced, a rotational shear failure zone will appear in the vertical plane. This failure mode is manifested as rotational shear failure of the soil near the pile end, usually accompanied by significant pile end reaction and shear force. That is, for the lower rotational failure zone, the external load is dominated by the pile end resistance, pile side shear force, and pile end bending moment. For this reason, combined with Figure 6 The rotating destruction zone auxiliary unit 4 of the present invention includes a vertical spring 4-1 and a horizontal load-bearing beam 4-2; one end of the horizontal load-bearing beam 4-2 is fixed to the inner side of the longitudinal beam 52, and the other end extends horizontally to the bottom of the fan pile 6, and is connected and tightened with the bottom of the fan pile 6 through the vertical spring 4-1.

[0089] In addition, the bedrock embedded unit 5 of the present invention includes a group of tubular pile foundations 5-1 and a group of longitudinal beams 5-2 cast in the rock layer or hard soil area; the top of the tubular pile foundation 5-1 is connected to the upper rotational destruction zone auxiliary unit 4, the full flow destruction zone auxiliary unit 3, and the wedge-shaped destruction zone auxiliary unit 2 through the longitudinal beams 5-2.

[0090] Furthermore, the tension of the horizontal spring 2-1 of the present invention In the case of soft clay foundation, the following formula is satisfied:

[0091]

[0092] Where y represents the lateral displacement, y c Expressed as the critical lateral displacement, Expressed as the spring unit stiffness coefficient, Expressed as the change in the advance and contraction amount of the spring unit; is the design value of horizontal foundation soil reaction;

[0093] is the ultimate soil resistance, =γ′z1⋅D⋅Kp;

[0094] Where, γ′ is the effective bulk density;

[0095] D is the pile diameter;

[0096] Kp is the passive earth pressure coefficient;

[0097] z1 is the burial depth;

[0098] The horizontal spring 2-1 tension In the case of sandy soil foundation, the following formula must be satisfied:

[0099]

[0100] If the deformation of the soft sand around the pile foundation is allowed to enter the nonlinear stage within a certain range, and the displacement limit (such as the horizontal displacement of the pile top does not exceed 1%~2% of the wind turbine tower height) and fatigue life requirements must still be met, the setting of the auxiliary device does not need to be conservative. In this case, the horizontal spring tension is 2-1. The following formula must be satisfied:

[0101]

[0102] Where, k is the initial stiffness, k=E soil / D;E soil is the sand modulus; y represents the lateral displacement; D is the pile diameter;

[0103] is the effective vertical stress, , is the total vertical stress, u is the pore water pressure; Expressed as the horizontal spring unit stiffness coefficient, Expressed as the change in the advance and contraction of the horizontal spring unit; is the design value of horizontal foundation soil reaction; A is the empirical coefficient, A=3.0−0.8(z1 / D).

[0104] Furthermore, the tension of the longitudinal inclined spring 3-1 Satisfies the following formula:

[0105] In the case of soft clay foundation,

[0106]

[0107]

[0108] Among them, T is the side friction resistance on site, T max is the limiting lateral friction;

[0109] represents the adhesion coefficient; S u is the undrained shear strength, A s is the pile side surface area;

[0110] z2 is the lateral displacement, z 50 =0.02⋅D, D is the pile diameter;

[0111] Expressed as the stiffness coefficient of the longitudinal inclined spring unit;

[0112] Expressed as the change in the advance and contraction amount of the longitudinal inclined spring unit;

[0113] is the angle between the longitudinal inclined spring and the vertical direction;

[0114] T s It represents the designed pile side friction resistance;

[0115] In the case of sandy soil,

[0116]

[0117]

[0118]

[0119] Among them, T is the side friction resistance on site, T max is the limiting lateral friction;

[0120] is the vertical effective stress, δ is the friction angle of the pile-soil interface, δ = 0.5ϕ ∼ 0.8ϕ, ϕ is the internal friction angle of the soft soil;

[0121] is the pile side surface area;

[0122] is the dimensionless shear stiffness coefficient, usually taken as 1000∼2000;

[0123] k is the stiffness coefficient of sand;

[0124] z2 is the lateral displacement;

[0125] is the angle between the longitudinal inclined spring and the vertical direction;

[0126] Expressed as the stiffness coefficient of the longitudinal inclined spring unit, Expressed as the change in the longitudinal inclined spring unit's advance and contraction amount, T S It represents the design pile side friction.

[0127] Furthermore, the tension Q of the vertical spring 4-1 must satisfy the following formula:

[0128] In the case of soft clay foundation,

[0129]

[0130]

[0131] In the case of sandy soil,

[0132]

[0133]

[0134] Among them, Q is the field end resistance, Q max is the ultimate end resistance;

[0135] is the effective vertical stress at the pile tip, Su is the undrained shear strength, is the pile tip area, z3 is the vertical displacement of a single pile, z 50 =0.02⋅D, Expressed as the vertical spring unit stiffness coefficient, Expressed as the change in the vertical spring unit's advance and contraction, N q 、N γ is the bearing capacity coefficient, Effective bulk density of soil It is expressed as the change in the spring unit's advance and contraction, and Qs represents the designed pile end resistance;

[0136]

[0137]

[0138] Φ is the internal friction angle of soft soil.

[0139] In this invention, the spring unit is designed to ensure that the pile, when installed without any working conditions, already withstands the required reaction force from the spring unit. Large-diameter industrial springs are used. The ends of the oblique spring units are cast into the concrete pile. Magnetic encoders for different spring types are placed on the load-bearing plate, and permanent magnets are placed in the pile body or the square plate of the spring unit.

[0140] The bottom cylindrical bedrock embedding device of the auxiliary embedding device extends into the bottom rock layer. After drilling, concrete is poured on the upper part of the embedding device in the form of conduit grouting to fix it. Special materials such as anti-dispersant need to be added to the concrete.

[0141] Based on the Timoshenko beam model, this invention treats the rigid-flexible pile as a cantilever beam, utilizing this device to fully supplement the bearing capacity that weak soil cannot bear. Furthermore, in terms of the layout of the unit modules, the device is divided into four sections, with detailed divisions based on the distribution of the destructive effects of soil loading. These include an upper anti-scour section, a middle-upper wedge-shaped failure zone, a middle-lower full-flow failure zone, and a lower rotational failure zone. Different spring unit arrangements are used in different areas. The coupling effect of nonlinear springs (foundation soil) and linear springs is utilized to meet design requirements, fully simulating the actual pile-soil interaction distribution. A magnetic encoder is added to the spring unit module to monitor the status of a single pile in real time. The magnetic encoder is placed at the corresponding spring position on the cylindrical load-bearing device, and the permanent magnet is placed on the square load-bearing plate. Compared to other devices, this is more targeted and has better reliability and embedding effects.

[0142] Combine Figure 7 The present invention can be adjusted for soft soils in three different types of piles: flexible piles, rigid-flexible piles, and rigid piles. The layout dimensions of the device's three destruction zones can be adjusted according to site conditions, and the arrangement and combination can be tailored to the properties of the soft soil, making the device suitable for different types of piles and different foundation soils, greatly enhancing the applicability of the invention. For example, in the case of flexible piles on sandy foundations, the auxiliary embedding device can directly remove the layout of the rotational destruction zone device, appropriately extend the layout dimensions of the wedge-shaped destruction zone and full-flow destruction zone devices, and determine the spring stiffness using the same method for determining spring stiffness in sandy foundations.

[0143] The present invention provides a concept and method for a monitorable, embedded, and scour-proof device for pile foundations in soft soil. While there are numerous methods and approaches for implementing this technical solution, the foregoing is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art could make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. A monitorable, embedded and scour-proof device for pile foundations in soft soil, characterized in that: It comprises an anti-scour nested unit (1), a wedge-shaped damage zone auxiliary unit (2), a full-flow damage zone auxiliary unit (3), a rotational damage zone auxiliary unit (4), and a bedrock embedded unit (5), which are sequentially sleeved on the outer wall of a wind turbine single pile (6) from top to bottom; The bedrock embedded unit (5) is pre-buried at the bottom of the wind turbine pile (6) and is sequentially connected to the upper rotational destruction zone auxiliary unit (4), the full flow destruction zone auxiliary unit (3), and the wedge-shaped destruction zone auxiliary unit (2) through a set of longitudinal beams (52); A group of horizontal springs (2-1) are connected between the wedge-shaped destruction zone auxiliary unit (2) and the outer wall of the fan single pile (6), and the horizontal springs (2-1) have a preset tension; the full-flow destruction zone auxiliary unit (3) is connected to the outer wall of the fan single pile (6) through a group of longitudinal inclined springs (3-1), and the longitudinal inclined springs (3-1) have a preset tension; the rotational destruction zone auxiliary unit (4) is connected to the bottom of the fan single pile (6) through a vertical spring (4-1), and the vertical spring (4-1) has a preset tension; each spring module is respectively provided with an elastic force sensor and a magnetic encoder for real-time monitoring of the status of the fan single pile (6).

2. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 1 is characterized in that: The anti-scour nested unit (1) comprises an annular sleeve (1-2) and a diversion pile barrel (1-1); the annular sleeve (1-2) is fixed to the outer wall of the wind turbine pile (6) by interference fit; the diversion pile barrel (1-1) is sleeved on the outside of the wind turbine pile (6) and located below the annular sleeve (1-2); the bottom of the diversion pile barrel (1-1) is connected to the cylindrical load-bearing device (2-2) of the wedge-shaped damage zone auxiliary unit (2); the outer wall of the diversion pile barrel (1-1) is provided with a diversion groove (1-3) along the scouring direction of the water flow.

3. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 1 is characterized in that: The wedge-shaped destruction zone auxiliary unit (2) includes a group of cylindrical load-bearing devices (2-2); the cylindrical load-bearing devices (2-2) are connected in sequence from top to bottom through a group of longitudinal beams (5-2), so as to be mounted on the periphery of the wind turbine pile (6); the inner wall of each cylindrical load-bearing device (2-2) is connected to the outer wall of the wind turbine pile (6) through a group of horizontal springs (2-1); the horizontal springs (2-1) are distributed at equal intervals in the annular direction; and the outer wall of the wind turbine pile (6) is provided with a square load-bearing sheet (2-3) corresponding to each horizontal spring (2-1).

4. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 3 is characterized in that: There are more than two cylindrical load-bearing devices (2-2) which are sequentially buried in the soft soil area along the longitudinal direction of the wind turbine pile (6), and the bottom cylindrical load-bearing device (2-2) is arranged at the bottom position of the wind turbine pile (6).

5. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 1 is characterized in that: The full-flow destruction zone auxiliary unit (3) includes an oblique spring bearing cylinder (3-2) and a group of longitudinal oblique tension springs (3-1); the oblique spring bearing cylinder (3-2) is arranged at the middle and lower part of the fan single pile (6); one end of the longitudinal oblique tension spring (3-1) is fixed on the top outer wall of the fan single pile (6), and the other end is fixed on the oblique spring bearing cylinder (3-2); each longitudinal oblique tension spring (3-1) is evenly distributed in the ring direction; a group of oblique spring bearing plates (3-3) for fixing the longitudinal oblique tension springs (3-1) are arranged on the inner wall of the oblique spring bearing cylinder (3-2).

6. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 1 is characterized in that: The rotational destruction zone auxiliary unit (4) includes a vertical spring (4-1) and a horizontal load-bearing beam (4-2); one end of the horizontal load-bearing beam (4-2) is fixed to the inner side of the longitudinal beam (52), and the other end extends horizontally to the bottom of the fan pile (6) and is connected and tightened with the bottom of the fan pile (6) through the vertical spring (4-1).

7. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 1 is characterized in that: The bedrock embedded unit (5) comprises a group of tubular pile foundations (5-1) and a group of longitudinal beams (5-2) cast in a rock layer or a hard soil area; the top of the tubular pile foundation (5-1) is connected to the upper rotational destruction zone auxiliary unit (4), the full flow destruction zone auxiliary unit (3), and the wedge-shaped destruction zone auxiliary unit (2) respectively through the longitudinal beams (5-2).

8. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 3 is characterized in that: The horizontal spring (2-1) tension In the case of soft clay foundation, the following formula is satisfied: ； Where y represents the lateral displacement, y c Expressed as the critical lateral displacement, Expressed as the spring unit stiffness coefficient, Expressed as the change in the advance and contraction amount of the spring unit; is the design value of horizontal foundation soil reaction; is the ultimate soil resistance, =γ′z1⋅D⋅Kp; Where, γ′ is the effective bulk density; D is the pile diameter; Kp is the passive earth pressure coefficient; z1 is the burial depth; The horizontal spring (2-1) tension In the case of sandy soil foundation, the following formula must be satisfied: ； If the deformation of the soft sand around the pile foundation is allowed to enter the nonlinear stage within a certain range and the displacement limit and fatigue life requirements are still required to be met, the setting of the auxiliary device does not need to be conservative. In this case, the tension of the horizontal spring (2-1) The following formula must be satisfied: ； Where, k is the initial stiffness, k=E soil / D;E soil is the sand modulus; y represents the lateral displacement; D is the pile diameter; is the effective vertical stress, , is the total vertical stress, u is the pore water pressure; Expressed as the horizontal spring unit stiffness coefficient, Expressed as the change in the advance and contraction of the horizontal spring unit; is the design value of horizontal foundation soil reaction; A is the empirical coefficient, A=3.0−0.8(z1 / D).

9. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 5, characterized in that: The tension of the longitudinal inclined spring (3-1) Satisfies the following formula: In the case of soft clay foundation, ； ； Among them, T is the side friction resistance on site, T max is the limiting lateral friction; represents the adhesion coefficient; S u is the undrained shear strength, A s is the pile side surface area; z2 is the lateral displacement, z 50 =0.02⋅D, D is the pile diameter; Expressed as the stiffness coefficient of the longitudinal inclined spring unit; Expressed as the change in the advance and contraction amount of the longitudinal inclined spring unit; is the angle between the longitudinal inclined spring and the vertical direction; T s It represents the designed pile side friction resistance; In the case of sandy soil, ； ； ； Among them, T is the side friction resistance on site, T max is the limiting lateral friction; is the vertical effective stress, δ is the friction angle of the pile-soil interface, δ = 0.5ϕ ∼ 0.8ϕ, ϕ is the internal friction angle of the soft soil; is the pile side surface area; is the dimensionless shear stiffness coefficient, usually taken as 1000∼2000; k is the stiffness coefficient of sand; z2 is the lateral displacement; is the angle between the longitudinal inclined spring and the vertical direction; Expressed as the stiffness coefficient of the longitudinal inclined spring unit, Expressed as the change in the longitudinal inclined spring unit's advance and contraction amount, T S It represents the design pile side friction.

10. The monitorable, embedded and anti-scour integrated device for pile foundations in soft soil according to claim 6, characterized in that: The vertical spring (4-1) tension Q must satisfy the following formula: In the case of soft clay foundation, ； ； In the case of sandy soil, ； ； Among them, Q is the field end resistance, Q max is the ultimate end resistance; is the effective vertical stress at the pile tip, Su is the undrained shear strength, is the pile tip area, z3 is the vertical displacement of a single pile, z 50 =0.02⋅D, Expressed as the vertical spring unit stiffness coefficient, Expressed as the change in the vertical spring unit's advance and contraction, N q 、N γ is the bearing capacity coefficient, Effective bulk density of soil Qs represents the design pile tip resistance; where, ； ； Φ is the internal friction angle of soft soil.

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