KR20150126127A - An analysis of the multi-layered soil on monopile foundation of offshore wind tower - Google Patents

Abstract

The present invention relates to a method for analyzing a multi-layered ground on a monopole foundation of an offshore wind tower. More specifically, the method comprises: an external strength calculating step of calculating external strength applied to the offshore wind tower; a displacement calculating step of calculating a displacement of a tower base by using the external strength calculated from the external strength calculating step; and a ground reaction calculating step of calculating a ground reaction of the ground by using the displacement calculated from the displacement calculating step. The external strength calculating step comprises: a wind calculating step of calculating wind applied to the tower by wind; a wave strength calculating step of calculating wave strength applied to the power by wave; and a thrust calculating step of calculating thrust applied to the tower by rotation of a blade. Overall substantial external strength applied to a tower of an offshore wind generator is considered, and subgrade reaction is respectively calculated according to a soil constituting the ground. The same may be applied to a multi-layered ground, and an interaction between a base of the tower and the surrounding ground can be accurately analyzed.

Description

[0001] The present invention relates to a multi-layer ground analysis method for a monofilament foundation of an offshore wind tower,

The present invention relates to a multi-layer ground analysis method for a monofilament foundation of an offshore wind tower, and more particularly, to a multi-layer ground analysis method for an offshore wind tower, And a ground reaction force calculation step of calculating a ground reaction force of the ground by using the displacement calculated in the displacement calculation step, and the external force calculation step is a step of calculating a wind reaction force acting on the tower by the wind Calculating a wave power to calculate a wave force acting on the tower by wave and calculating a thrust force acting on the tower by rotation of the blade, and calculating a thrust force on the tower of the offshore wind power generator Considering all the substantial external forces and calculating the ground reaction force according to the soil (soil) constituting the ground, The present invention relates to a multi-layer ground analysis method for a monofilament foundation of an offshore wind tower that can be applied to the ground and accurately interpret the interaction between the foundation of the tower and the surrounding ground.

In recent years, research and development of environmentally friendly renewable energy using wind power, tidal power, and solar heat have been widely performed due to problems such as depletion of resources, environmental pollution caused by the use of fossil fuels, and greenhouse effect. Wind energy, which is a type of renewable energy, is divided into two categories of off-shore wind power generation and offshore wind power generation as pollution-free energy sources. Wind speed that determines the generation amount of wind power generation has high quality in the sea, The center of gravity is shifting to offshore wind power generation rather than land based on the reasons such as the establishment of installation site due to fire, electromagnetic wave, noise problem, and the like. Unlike onshore wind towers, offshore wind towers are subject to additional external forces due to waves, and the conditions of offshore and offshore grounds are different. Therefore, such conditions should be considered when installing offshore wind towers.

Conventional techniques including the following documents and patent documents are based on the numerical analysis of the waves acting on the vertical circumference installed on the sea and securing the stability of the structure against algae and waves through structural modification literature).

(Articles)

Kim, N. H and Cao, T. N.T. (2008), "Wave force analysis of the two vertical cylinders by boundary element method", KSCE Journal of Civil Engineering, Vol. 12, No. 6, pp. 359-366.

(Patent Literature)

Open Patent Publication No. 10-2013-0034755 (published on Mar. 04, 08, 2013) "Support structure for offshore wind power generation and construction method thereof"

However, since the support structure for offshore wind power generation is designed to secure structural stability against algae and waves through structural modification, data for analyzing the interaction between the force acting on the support structure and the ground is not presented, It is unclear in what geological environment it can be achieved that the above objective can be achieved and the method of interpreting the interaction between the marine structure including the above paper and the ground is limited to the limited external force acting on the marine structure (Single layer ground), it is limited to be applied to the design and installation of an actual offshore wind tower.

Therefore, in order to secure the safety of the installed offshore wind tower, it is necessary to consider the wind force, wave force, and thrust force which have a substantial effect on the offshore wind tower and to provide the foundation of the wind tower which can be applied in multi- There is an increasing need for an analysis method capable of accurately interpreting the interaction between surrounding grounds.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems,

The present invention takes into account all the substantial external forces exerted on the towers of an offshore wind turbine and calculates the ground reaction forces according to the soil (soil) constituting the ground. Therefore, the present invention can be applied to multi- The present invention provides a multi-layered ground analysis method for a monofilament foundation of an offshore wind tower which can be accurately interpreted.

In addition, considering the wind force, the wave force, and the thrust force as the external force applied to the tower, the present invention considers the ground composed of the sandy soil and the clayey soil as the ground on which the tower is installed. Therefore, in the environment similar to the actual environment where the offshore wind power generator is installed, The present invention provides a multi-layer ground analysis method for a monofilament foundation of an offshore wind tower having the same effect as that of analyzing an interaction between a ground and a surrounding ground.

In addition, the present invention estimates the wind wave (significant wave period, significant wave height) according to the SMB method, and uses the Morison formula to calculate the wave power, thereby increasing the wave accuracy and reducing the loss due to the rotation of the blades The present invention provides a method of analyzing a multi-layered ground structure on a monofilament foundation of an offshore wind tower capable of enhancing the accuracy of thrust.

In the present invention, the ground reaction force is divided into the elastic range and the plastic range in the calculation of the ground reaction force, and the ground reaction force is divided into the vicinity of the ground surface and the predetermined depth in the plastic range. Therefore, The purpose of this paper is to provide a multi-layered ground analysis method for pile foundation.

In order to achieve the above object, the present invention is implemented by the following embodiments.

The multi-layer ground analysis method of the monofile foundation of the offshore wind tower according to an embodiment of the present invention includes an external force calculation step of calculating an external force applied to an offshore wind tower and a tower foundation based on the external force calculated in the external force calculation step. And a ground reaction force calculation step of calculating a ground reaction force of the ground by using the displacement calculated in the displacement calculation step, wherein the external force calculation step is a step of calculating a wind reaction force acting on the tower by the wind Calculating a wave power to calculate a wave force acting on the tower by waves; and calculating a thrust force acting on the tower by rotation of the blades.

In the multi-layer ground analysis method of the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, the displacement calculation step may include a step of estimating the displacement of the wind turbine tower based on the wind power estimated in the wind power calculation step, the wave power calculated in the wave power calculation step, The shear force is calculated using the thrust calculated by the shear force, the moment is calculated using the shear force, and the displacement of the tower foundation is calculated using the moment.

In the multi-layer ground analysis method of the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, in the step of calculating the wind power, the wind power is obtained by calculating the vertical distribution of the wind speed according to the power law for each wind speed, The thrust is calculated in consideration of the loss due to the rotation of the blade between the cut in wind speed and the cut out wind speed at which the blade is operated.

According to another embodiment of the present invention, in the multi-layer ground analysis method of the monofilament foundation of the offshore wind tower, the wave power calculation step calculates wind waves according to the SMB method and uses the Morris equation to calculate the wave power .

In the multi-layer ground analysis method of the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, the ground reaction force calculation step divides the ground consisting of sand soil and the qualitative soil, respectively, and in the case of the ground comprising sand soil, And the plastic range, and in the plastic range, the ground reaction force is calculated by dividing it into the vicinity of the ground surface and a certain depth.

In the multi-layered ground analysis method for the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, the vicinity of the certain depth means a point where the ground reaction force increases and then starts to decrease from the bottom to the top of the ground.

In the multi-layer ground analysis method of the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, the thrust may reflect the loss rate calculated by the following equation (5) to the value calculated by the following equation (4) .

In the multi-layer ground analysis method of the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, the ground reaction force in the elastic range of the sand soil layer is obtained by the following equation (9) And the ground reaction force in the vicinity of the ground surface is obtained by the following equation (10), and the soil reaction force in the vicinity of the sintering range and the certain depth of the sandpaper soil is obtained by the following equation (11).

In the multi-layer ground analysis method for the monofilament foundation of the offshore wind tower according to another embodiment of the present invention, the ground reaction force of the clay soil can be calculated by calculating the ultimate soil strength per unit length of the file using Equation (12) The ground reaction force is finally calculated through Equation (15) by calculating the refraction at half of the ultimate ground resistance through Equation (13), calculating the remaining ground resistance through Equation (14) do.

Another embodiment of the present invention is characterized in that a multi-layered ground analysis method for a monofilament foundation of an offshore wind tower according to any one of claims 1 to 9 is programmed and recorded.

The present invention can obtain the following effects by the above-described embodiment, the constitution described below, the combination, and the use relationship.

The present invention takes into account all the substantial external forces exerted on the towers of an offshore wind turbine and calculates the ground reaction forces according to the soil (soil) constituting the ground. Therefore, the present invention can be applied to multi- There is an effect that can be accurately interpreted.

In addition, considering the wind force, the wave force, and the thrust force as the external force applied to the tower, the present invention considers the ground composed of the sandy soil and the clayey soil as the ground on which the tower is installed. Therefore, in the environment similar to the actual environment where the offshore wind power generator is installed, And the interaction between the surrounding ground and the surrounding ground.

In addition, the present invention estimates the wind wave (significant wave period, significant wave height) according to the SMB method, and uses the Morison formula to calculate the wave power, thereby increasing the wave accuracy and reducing the loss due to the rotation of the blades So that the accuracy of thrust can be improved.

Further, in calculating the soil reaction force of the sand soil, the soil reaction force is divided into the elastic range and the plastic range, and in the plastic range, the ground reaction force is divided into the vicinity of the ground surface and the vicinity of the predetermined depth, so that the accuracy of the ground reaction force can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart of a method for multi-layered ground analysis on a monofilament foundation of an offshore wind tower of the present invention. FIG.
2 is a diagram showing an external force acting on an offshore wind power generator;
3 is a graph showing wind force along a height according to the present invention;
4 is a graph showing wave power along a height according to the present invention.
5 is a graph showing the thrust according to the wind speed according to the present invention.
6 is a graph showing the shear force according to depth according to the present invention.
7 is a graph showing moments along depth according to the present invention.
8 is a graph depicting the displacement of the foundation along the depth according to the invention.
9 is a graph showing the ground reaction force according to the depth according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a method for analyzing a multi-layered ground on a monofilament of a offshore wind tower according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Throughout the specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

FIG. 2 is a diagram showing an external force acting on an offshore wind power generator, and FIG. 3 is a view showing a wind force along a height according to an embodiment of the present invention. FIG. FIG. 5 is a graph showing the thrust according to the wind speed according to the present invention, and FIG. 6 is a graph showing the shear force according to the depth according to the present invention. FIG. Fig. 7 is a graph showing moments along the depth according to the present invention, Fig. 8 is a graph showing the displacement of the foundation according to the depth according to the present invention, Fig. 9 is a graph showing the depth Of the ground reaction force.

1 to 9, the ground analysis method includes an external force calculation step S1 for obtaining an external force applied to the tower, A displacement calculating step S2 for calculating the displacement of the tower foundation by using the external force calculated in the external force calculating step S1, and a calculating step S2 for calculating the ground reaction force of the ground using the displacement calculated in the displacement calculating step S2 A ground reaction force calculation step (S3), and the like. The offshore wind turbine generator 100 includes an offshore wind turbine tower 110 mounted on the sea and grounded on the power generator 120, And a power generating unit 120 installed on the upper portion of the power generating unit 120 to generate electricity while being rotated by the wind. The base 111 positioned at the lower end of the tower 110 is inserted and fixed in the ground 200 of the seabed. The power generator 120 includes a nacelle 121 having a built-in generator and a nacelle 121 121 and a rotor 122 having a plurality of blades 123 and the like. The ground analysis method is based on the assumption that the foundation 111 of the tower 110 is formed of a monolithic type, a mono type type, a jacket type and a floated type in accordance with the type of the foundation 111 of the tower 110, The structure-foundation-ground is connected to the equivalent spring motel, and the ground 200 is assumed to be composed of sandy soil, clayey soil, and the like.

The external force calculating step (S1) is a step of obtaining an external force exerted on the tower, and the external force obtained in the external force calculating step (S1) is used to obtain the displacement of the foundation of the tower. Wind force due to direct action of wind, wave caused by wind, and thrust caused by the rotation of the blade (rotor) by the wind act on the tower as an external force. The external force calculation step S1 includes a wind force calculation step S11, a wave power calculation step S12, a thrust calculation step S13, and the like.

The wind power calculating step S11 is a step of calculating the wind force acting on the tower by the wind, and the wind power is obtained by calculating a vertical distribution of the wind speed according to the power law for each wind speed. In the wind power calculation step S11, the wind force applied to the tower is obtained by the following equation (1).

,

이고, F_t는 타워에 작용하는 풍력, A는 타워의 높이별 수풍면적, H는 지상으로부터의 높이, n은 멱지수로 해양과 같이 장애물이 없는 지역에서는 0.1, G_r은 거스트 계수로 장애물이 없는 지형일 때 10m이하에서는 2.0, 40m이상에서는 1.8, 그 사이 범위에서는 두 값을 직선 보간 한 값, U는 평균풍속(m/s)이고, D는 타워의 직경)(here,

,

And, F _t is the wind acting on the tower, A is the height of each supung area of the tower, H is in the area free of obstacles, such as marine a height from the ground, n is the exponent 0.1, G _r are free of obstacles to geoseuteu coefficient (M / s), and D is the diameter of the tower). In the case of the terrain, it is 2.0 at the distance of 10m or less, 1.8 at the distance of 40m or more,

The wave power calculation step S12 is a step of calculating the wave power acting on the tower by the wave. The wave power is calculated by the following equation (2) (SMB method, Sverdrup-Munk Bretschneider method) Wave height and maximum wave height), and the wave power on the tower is obtained by using the value of the wind wave by the following expression (3) (Morrison formula). The water particle horizontal velocity and the water particle horizontal acceleration of Equation (3) are obtained by using the meaningful wave period, the significant wave height and the maximum wave height obtained from Equation (2), so that detailed explanation will be omitted.

(Where, H _1/3 the significant wave height, T _1/3 is significant wave period, H _max is the maximum wave height, u is _a velocity, g is the acceleration of gravity)

는 물입자 수평가속도, y는 지반에서의 높이 )(Where, F is the wave power, ρ is the density of sea water, C _D is the drag coefficient, D is the diameter of the tower, u is the horizontal velocity of water particles, C _M is the mass coefficient,

Is the water particle horizontal acceleration, and y is the height in the ground)

The step S13 of calculating the thrust is a step of calculating a thrust acting on the tower by rotation of the blade. The step S13 is a step of calculating the thrust of the blade The thrust is calculated by considering the loss due to the thrust. In the thrust calculation step S13, the final thrust force acting on the tower is calculated by correcting the thrust calculated by reflecting the loss rate calculated by the equation (5) from the thrust calculated by the equation (4).

(Where F _thrust is thrust, ρ _α is air density, C _F is thrust coefficient, and U is wind speed)

)
(Where f is the loss factor, N is the number of blades, μ is the non-dimensionless variable (0.05) for the local position of the blade from the hub to the tip, λ is the design speed ratio (6), u is the wind speed,

)

The displacement calculation step S2 is a step of calculating the tower foundation displacement using the external force calculated in the external force calculation step S1. The wind power calculated in the wind power calculation step S11, the wave power calculation step S12, The shear force is calculated using the wave force calculated in the thrust calculation step S13 and the shear force calculated in the thrust calculation step S13 (using Equation 6), the moment is obtained using the shear force (using Equation 7) The displacement of the foundation (using Equation 8) is calculated.

(Where V is the shear force, q is the load, y is the longitudinal axis length, and the load is the sum of wind force, wave force, and shear force)

(Where M is moment, V is shear force, y is longitudinal axis length)

(Where v is the displacement of the tower foundation, M is the moment, E is the modulus of elasticity of the pile, I is the moment of inertia of the cross section,

The ground reaction force calculation step S3 is a step of calculating a ground reaction force of the ground using the displacement calculated in the displacement calculation step S2. The ground reaction force calculation step S3 is a step of calculating a ground reaction force ).

The ground reaction force calculation step is a step of calculating the ground reaction force against the displacement of the foundation when the ground is made of the sandy soil layer. The ground reaction force is divided into the elastic range and the plastic range of the ground, and in the plastic range, And the ground reaction force is calculated. When the displacement of the structure installed on the ground is sufficiently large, the ground becomes plasticized. Before the plasticization, the ground is in the elastic range, and after the plasticization, the ground is in the plastic range. The vicinity of the certain depth means a point where the ground reaction force increases and then starts to decrease from the bottom to the top of the ground. The soil reaction force in the elastic range of the ground is obtained by the following equation (9), and the plastic reaction range of the ground and the ground reaction force in the vicinity of the ground surface are obtained by the equation (10) The reaction force is obtained by equation (11).

(Where p is the soil reaction force, B is the diameter of the foundation, k is the number of springs, z is the depth at the surface of the earth,

, γ는 흙의 보정계수, z는 지표면에서의 깊이, K₀는 0.4, φ는 모래의 내부마찰각, β는 45°+φ/2, α는 φ/2, K_A는 tan²(45°-φ/2))(Where p _u is the ultimate ground reaction force, B is the diameter of the foundation, A _u is the empirical correction factor, and P _c is the ultimate resistance

φ is the internal friction angle of the sand, β is 45 ° + φ / 2, α is φ / 2, K _A is tan ² (45 °), γ is the correction coefficient of soil, z is depth on the surface, K ₀ is 0.4, -φ / 2))

, γ는 흙의 보정계수, z는 지표면에서의 깊이, K₀는 0.4, φ는 모래의 내부마찰각, β는 45°+φ/2, α는 φ/2, K_A는 tan²(45°-φ/2))(Where p _u is the ultimate ground reaction force, B is the diameter of the foundation, A _u is the empirical correction factor, and P _c is the ultimate resistance

φ is the internal friction angle of the sand, β is 45 ° + φ / 2, α is φ / 2, K _A is tan ² (45 °), γ is the correction coefficient of soil, z is depth on the surface, K ₀ is 0.4, -φ / 2))

The step of estimating the reaction force of the clayey soil is a step of calculating the soil reaction force with respect to the displacement of the foundation when the clayey soil is composed of clayey soil, calculating the ultimate soil strength per unit length of the pile (using Equation 12) (Using Equation 13), calculating the remaining ground resistance (using Equation 14), and finally calculating the ground reaction force using the above calculated value (using Equation 15).

Where P _u is the ultimate soil strength per unit length of the file, γ is the correction factor of the soil, C _u is the undrained shear strength, z is the depth, D is the file diameter and J is the empirical dimensionless parameter (0.5)

(Where y50 is the refraction at half the ultimate soil resistance, epsilon ₅₀ is the strain corresponding to half the maximum principal stress, and D is the diameter of the pile)

Where P _rest is the soil resistance (reaction force) at the remainder of the ultimate soil resistance, P _u is the ultimate soil strength per unit length of the file, z is the depth, C _u is the undrained shear strength, D is the file diameter, Dimensionless parameter (0.5), y is the correction coefficient of soil)

Where p is the soil reaction force, P _u is the ultimate soil strength per unit length of the pile (reaction force), P _rest is the soil resistance (reaction force) at the _rest of the ultimate soil resistance, y is the tower foundation displacement, y50 is the ultimate soil resistance Refraction in half)

Using the above-described ground analysis method, it is possible to accurately calculate the load (sum of external forces) acting on the tower before installing the offshore wind turbine generator, and to use the actual constants of the surrounding grounds It is possible to calculate the ground reaction force accurately, and the value calculated in the above can be utilized in the design of the tower foundation of the offshore wind power generator.

Hereinafter, a specific application example of the soil analysis method including the above steps will be described with reference to FIGS. 1 to 9. FIG. In the above application example, the water depth is 30 m, the height of the tower is 30 m below the water surface, 80 m above the water surface, the penetration depth of the foundation is 30 m and the tower has a constant diameter of 3.87 m in the upper diameter and 6 m in the lower diameter. 5MW, with a file thickness of 60mm. The monofile is STK 490 steel, with a modulus of elasticity of 210,000MPa and a unit weight of 77kN / m ³ . In case of wind speed, 10m / s, 20m / s and 30m / s were used to confirm the influence of thrust. The blade data for modeling the blade were applied to NREL developed S826, S825 and S818. Soil was set to a total of four layers, the depth are each 11m, 7m, 7m, a total of 30m to 5m to the top as the starting point, the first 11m is clay, and wherein undrained shear strength C _u and the effective weight per unit area of γ is 150kN / and m ² and 12kN / m ^3, the remaining soil is sand and the internal friction angle and γ is from 30 ° and 15.7kN / m ^3, 36 ° and 20kN / m ^3, the middle value of 33 ° and 17.4kN / m ³ upper .

The wind force acting on the offshore wind tower is calculated by Equation 1 and the result is shown in FIG. 3, the wind speed at sea calculated by the power function increases as the altitude increases, but as the altitude increases, the width of the increase in the wind speed decreases, and in the marine tower where the diameter decreases constantly according to the height, It can be seen that a larger wind force acts on the lower diameter portion. In addition, at 10m / s and 20m / s, which are the operating ranges of the rotor, it can be seen that the magnitude of the wind force applied to the tower sharply decreases due to loss of wind caused by rotation of the blades.

The wave force acting on the offshore wind tower is calculated by calculating the wave height using Equation (2) and applying the result to Equation (3), and the result is shown in FIG. 4, the magnitude of the generated wave increases as the wind speed increases.

The thrust acting on the offshore wind tower is firstly calculated by the following equation (4), and the thrust is finally calculated by reflecting the loss rate caused by the rotation of the blade calculated by the equation (5) Will be shown together. 5, the thrust increases rapidly between the cut-in wind speed of 4 m / s and the wing tip loss of 7 m / s, and after 7 m / s, the thrust increases slightly due to the wing tip loss Was gradually decreased after 15m / s. At a cut-out wind speed of 25 m / s, the thrust suddenly decreases, after which the blade is only affected by wind speed, not thrust.

FIG. 6 is a view showing the shear force calculated by the equation (6), FIG. 7 is a view showing a moment calculated by the equation (7), FIG. 8 is a diagram showing the displacement of the foundation calculated by the equation (8) FIG. 9 is a view showing the ground reaction force calculated from the equations (9) to (15). As shown in FIGS. 6 to 9, as the wind speed increases, the ground deformation increases due to the deformation of the monofilaments. Shear force and moment are proportional to the ground reaction force . It can be seen that the reaction force of the ground is heavily influenced by the ground reaction force coefficient of each soil, and as the deformation of the ground increases in the same ground layer, the ground reaction force also increases. However, after half of the foundation depth, the decrease of the soil reaction force can be confirmed. It is considered that this is due to the reduction of the soil reaction force coefficient due to the reduction of the overburden of the ground as it approaches the surface. Therefore, it is possible to calculate the external force acting on the offshore wind tower of a certain standard to be installed through the above-described ground analysis method, and to calculate the ground reaction force of the ground to be installed, And the stiffness of the foundation of the tower can be predicted.

Another embodiment of the present invention includes a recording medium on which a multi-layer ground analysis method for the monofilament foundation of the offshore wind tower is programmed and recorded.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Should be interpreted as belonging to the scope.

100: Offshore wind turbine generator 110: Tower 120: Power generator
111: Foundation 121: Nacelle 122: Rotor
123: The blade

Claims (10)

A step of estimating an external force applied to the offshore wind tower, a step of calculating a displacement of the tower foundation by using the external force calculated in the step of estimating the external force, and a step of calculating a displacement of the ground by using the displacement calculated in the displacement calculating step And a ground reaction force calculation step of calculating the ground reaction force,
The external force calculating step may include a wind power calculating step of calculating wind power acting on the tower by the wind, a wave power calculating step of calculating a wave power acting on the tower by the wind generated by the wind, And a thrust calculation step of estimating a thrust acting on the tower by the first and second sensors. 2. The method according to claim 1, wherein the displacement calculation step
The shear force is obtained using the wind force calculated in the wind power calculation step, the wave power calculated in the wave power calculation step, and the thrust calculated in the thrust calculation step, the moment is obtained using the shear force, A method for multi-layered ground analysis for a monofilament foundation of an offshore wind tower, characterized in that the displacement is calculated. 3. The method of claim 2,
In the step of estimating wind power, the wind power is obtained by calculating a vertical distribution of wind speed according to a power law,
Wherein the thrust is calculated in consideration of loss due to rotation of the blade between a cut in wind speed and a cut out wind speed at which the blade is operated in the step of estimating the thrust. 4. The method of claim 3, wherein the wave power calculation step
A method of multi-layer ground analysis for a monofilament foundation of an offshore wind tower, characterized in that the wind waves are calculated according to the SMB method and the wave power is calculated by the Morison equation. The method of claim 2, wherein the ground reaction force calculation step
And the soil zone composed of sandy soil is divided into the elastic range and the plastic zone of the ground and the ground reaction force is divided into the vicinity of the ground surface and the vicinity of the ground surface in the plastic range, Multi - layer ground analysis method for monofilament foundation. 6. The method of claim 5,
Wherein the ground reaction force is increased from the lower part of the ground to the upper part of the ground, and then begins to decrease. 3. The method of claim 2,
Wherein the thrust is estimated by reflecting a loss rate calculated by the following equation (5) to a value calculated by the following equation (4): " (5) "
&Quot; (4) "

(Where F _thrust is thrust, ρ _α is air density, C _F is thrust coefficient, and U is wind speed)
&Quot; (5) "

(Where f is the loss factor, N is the number of blades, μ is the non-dimensionless variable (0.05) for the local position of the blade from the hub to the tip, λ is the design speed ratio (6), u is the wind speed,

) 8. The method of claim 7,
The soil reaction force in the elastic range of the sandy soil is obtained by the following equation (9), and the plastic reaction range of the sandy soil and the ground reaction force in the vicinity of the surface are obtained by the following equation (10) Wherein the ground reaction force at a certain depth is obtained by the following equation (11). ≪ EMI ID = 11.0 >
&Quot; (9) "

(Where p is the soil reaction force, B is the diameter of the foundation, k is the number of springs, z is the depth at the surface of the earth,
&Quot; (10) "

(Where p _u is the ultimate ground reaction force, B is the diameter of the foundation, A _u is the empirical correction factor, and P _c is the ultimate resistance

φ is the internal friction angle of the sand, β is 45 ° + φ / 2, α is φ / 2, K _A is tan ² (45 °), γ is the correction coefficient of soil, z is depth on the surface, K ₀ is 0.4, -φ / 2))
&Quot; (11) "

(Where p _u is the ultimate ground reaction force, B is the diameter of the foundation, A _u is the empirical correction factor, and P _c is the ultimate resistance

φ is the internal friction angle of the sand, β is 45 ° + φ / 2, α is φ / 2, K _A is tan ² (45 °), γ is the correction coefficient of soil, z is depth on the surface, K ₀ is 0.4, -φ / 2)) 9. The method of claim 8,
The ground reaction force of the clay soil is calculated by the following equation (12), and the refraction at half of the ultimate soil resistance is calculated by the following equation (13) And the ground reaction force is finally obtained through the following equation (15) by using the above calculated values. The method of claim 1, wherein the ground reaction force is obtained by the following equation (15).
&Quot; (12) "

Where P _u is the ultimate soil strength per unit length of the file, γ is the correction factor of the soil, C _u is the undrained shear strength, z is the depth, D is the file diameter and J is the empirical dimensionless parameter (0.5)
&Quot; (13) "

(Where y50 is the refraction at half the ultimate soil resistance, epsilon ₅₀ is the strain corresponding to half the maximum principal stress, and D is the diameter of the pile)
&Quot; (14) "

Where P _rest is the soil resistance (reaction force) at the remainder of the ultimate soil resistance, P _u is the ultimate soil strength per unit length of the file, z is the depth, C _u is the undrained shear strength, D is the file diameter, Dimensionless parameter (0.5), y is the correction coefficient of soil)
&Quot; (15) "

Where p is the soil reaction force, P _u is the ultimate soil strength per unit length of the pile (reaction force), P _rest is the soil resistance (reaction force) at the _rest of the ultimate soil resistance, y is the tower foundation displacement, y50 is the ultimate soil resistance Refraction in half) A recording medium on which a multi-layer ground analysis method for a monofilament foundation of an offshore wind tower according to any one of claims 1 to 9 is programmed and recorded.

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