A modeling analysis method suitable for large grip anchor group systems

Abstract

The application discloses a modeling analysis method suitable for a large-grab anchor group system, and comprises the following steps: S1, establishing an entity model of the large-grab anchor group system and seabed soil in a finite element model, and obtaining a finite element model main program; S2, applying an anchor chain tension to an anchor chain tension applying point at the front end of the mooring anchor chain entity model; S3, monitoring horizontal displacement and vertical displacement of the front mooring point and monitoring horizontal displacement and vertical displacement of the rear mooring point in the calculation process of the finite element model main program, and obtaining a motion trajectory curve of the large-grab anchor group system entity model. The application can improve the predictability of the embedding behavior of the large-grab anchor group system, improve the accuracy of numerical simulation, accurately depict the anchor chain tension borne by the real-time changing mooring anchor chain, the spatial form of the mooring anchor chain and the connecting anchor chain and the transmission tension, reduce the complexity of the finite element model modeling, and improve the calculation efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of deep-sea anchoring simulation, and particularly relates to a modeling analysis method suitable for a large-grab anchor group system. BACKGROUND

[0002] With the utilization of deep-sea resources and the development of deep-sea space, the mooring system of large marine floating platforms such as offshore floating wind power platforms, offshore oil and gas exploitation platforms, offshore airports and artificial floating islands becomes a key technology, and with the continuous increase of the operating water depth, the catenary mooring system has been widely applied, and higher requirements are put forward for the bearing performance and deep water installation performance of the anchoring structure in the catenary mooring system.

[0003] The existing typical deep water anchoring structures include suction anchors, drag-embedded plate anchors, suction-embedded plate anchors and gravity penetration anchors; the large-grab anchor as a kind of drag-embedded plate anchor has bearing characteristics suitable for the widely used semi-submersible offshore platform, and provides a bottom positioning foundation for the fields of offshore wind power, oil and gas and hydrogen production, and when the bearing performance requirement reaches the order of magnitude of 10000kN or more, the bearing efficiency of the large-grab anchor exceeds that of the suction anchor, and the cost of the anchoring structure can be reduced, so the large-grab anchor is one of the most promising deep-sea mooring anchoring forms.

[0004] The large-grab anchor is installed by means of mooring chain dragging, and gradually embedded into the seabed under the action of the reverse catenary of the mooring chain to reach the designed burial depth position and play the bearing performance to provide the positioning function for the upper marine floating platform. However, in actual production activities, with the increasing size of the marine floating platform, the demand for bearing performance is rapidly increasing. The above-mentioned large-grab anchor has the problems of insufficient bearing performance in soft seabed soil and shallow embedding depth, which affects the positioning stability and reliability of the marine floating platform in soft soil sea area; moreover, the embedding trajectory of the above-mentioned large-grab anchor is difficult to predict, and the size of the above-mentioned large-grab anchor is large, the cost of manpower and material resources for field test is high, in addition, the above-mentioned large-grab anchor has the problems of complex numerical simulation modeling and replacing the dynamic anchor chain tension with constant anchor chain tension, which interferes with the design and judgment of the embedding and bearing performance of the large-grab anchor in engineering practice. SUMMARY

[0005] In view of the defects of the above-mentioned prior art, the application provides a modeling analysis method suitable for a large-grab anchor group system, which can improve the predictability of the embedding behavior of the large-grab anchor group system, improve the accuracy of numerical simulation, accurately depict the anchor chain tension borne by the real-time changing mooring anchor chain and the spatial form and transmission tension of the mooring anchor chain and the connecting anchor chain, reduce the complexity of the finite element model modeling, and improve the calculation efficiency.

[0006] The technical scheme adopted by the application to solve the technical problems is as follows:

[0007] A modeling analysis method suitable for a large-grab anchor group system, the large-grab anchor group system comprising a front large-grab anchor and a rear large-grab anchor, a front end of the front large-grab anchor forming a front mooring point, the front mooring point being connected with a rear end of a mooring chain, a front end of the rear large-grab anchor forming a rear mooring point, and a connecting chain being arranged between the rear end of the front large-grab anchor and the rear mooring point;

[0008] The modeling analysis method comprises the following steps:

[0009] S1, establishing an entity model of the large-grab anchor group system and seabed soil in a finite element model, and obtaining a finite element model main program;

[0010] S2, applying a mooring chain tension to a mooring chain tension application point at a front end of the entity model of the mooring chain, and specifically comprising the following steps:

[0011] S2.1, compiling a subprogram for calculating the mooring chain tension and a loading angle, and obtaining a mooring chain tension loading angle subprogram;

[0012] S2.2, the mooring chain tension loading angle subprogram reading a vertical depth coordinate of the mooring chain tension application point at a current time from the finite element model main program;

[0013] S2.3, obtaining a loading angle according to the vertical depth coordinate and a preset initial value of the mooring chain tension;

[0014] S2.4, applying the mooring chain tension to the mooring chain tension application point according to the loading angle;

[0015] S2.5, the finite element model main program calculating a structural state of the entity model of the large-grab anchor group system at a next time according to the applied mooring chain tension and the loading angle, and updating the vertical depth coordinate of the mooring chain tension application point;

[0016] S2.6, judging whether a dragging speed meets a control speed according to a displacement size of the entity model of the mooring chain within a corresponding time period, and updating the mooring chain tension in the mooring chain tension loading angle subprogram;

[0017] S2.7, obtaining an updated loading angle according to the updated mooring chain tension and the updated vertical depth coordinate;

[0018] S2.8, the finite element model main program calculating and judging whether the entity model of the large-grab anchor group system is completed with the dragging installation, and if not, repeating steps S2.4-S2.7 until the dragging installation analysis is completed;

[0019] S3, monitoring a horizontal displacement and a vertical displacement of the front mooring point and monitoring a horizontal displacement and a vertical displacement of the rear mooring point in a calculation process of the finite element model main program, and obtaining a motion trajectory curve of the entity model of the large-grab anchor group system.

[0020] Further, in step S1, the entity model of the large-grab anchor group system is established in the finite element model, specifically including the following steps:

[0021] S1.1, establish a multi-section connecting anchor chain body entity model in the finite element model, and set rigid body condition constraints, set a rigid reference point at the front end of each section of the connecting anchor chain body entity model and a binding constraint point at the rear end; a first discrete line segment is established between the two adjacent sections of the connecting anchor chain body entity model, the front end of each first discrete line segment is connected to the binding constraint point at the rear end of the front section of the connecting anchor chain body entity model, and the rear end of each first discrete line segment is connected to the rigid reference point at the front end of the rear section of the connecting anchor chain body entity model; create a connection attribute for each first discrete line segment, so that the length of each first discrete line segment is constant and constitutes a first connection unit; the connecting anchor chain body entity model and the first connection unit cooperate to form a connecting anchor chain entity model;

[0022] S1.2, establish a front large-grab anchor entity model on the front side of the connecting anchor chain entity model and a rear large-grab anchor entity model on the rear side, and set rigid body condition constraints, set a rigid reference point at the front mooring point at the front end of the front large-grab anchor entity model and a binding constraint point at the connecting part at the rear end, and set a rigid reference point at the rear mooring point at the front end of the rear large-grab anchor entity model;

[0023] S1.3, a second discrete line segment is established with the rigid reference point at the front end of the connecting anchor chain entity model as an end point, a third discrete line segment is established with the binding constraint point at the rear end of the front large-grab anchor entity model and the binding constraint point at the rear end of the connecting anchor chain entity model as end points, and the rigid reference point at the front end of the rear large-grab anchor entity model; create a connection attribute for the second discrete line segment and the third discrete line segment, so that the length of the second discrete line segment is constant and constitutes a second connection unit, and the length of the third discrete line segment is constant and constitutes a third connection unit;

[0024] S1.4, establish a plurality of mooring anchor chain body entity models on the front side of the front large-grab anchor entity model, and set rigid body condition constraints, set a rigid reference point at the front end of each section of the mooring anchor chain body entity model and a binding constraint point at the rear end; a fourth discrete line segment is established between the two adjacent sections of the mooring anchor chain body entity model, the front end of each fourth discrete line segment is connected to the binding constraint point at the rear end of the front section of the mooring anchor chain body entity model, and the rear end of each fourth discrete line segment is connected to the rigid reference point at the front end of the rear section of the mooring anchor chain body entity model; create a connection attribute for each fourth discrete line segment, so that the length of each fourth discrete line segment is constant and constitutes a fourth connection unit; the mooring anchor chain body entity model and the fourth connection unit cooperate to form a mooring anchor chain entity model, wherein the rigid reference point at the front end of the mooring anchor chain entity model forms an anchor chain tension applying point;

[0025] S1.5. Establish a fifth discrete line segment with the binding constraint point at the rear end of the mooring anchor chain solid model as the endpoint to connect to the rigid reference point at the front end of the front high-holding anchor solid model; create connection attributes for the fifth discrete line segment so that the length of the fifth discrete line segment is constant and constitutes a fifth connection unit.

[0026] Furthermore, step S2.1 is specifically as follows: according to the geometric characteristics of the mooring anchor chain entity model, the effective width of the mooring anchor chain, the bearing coefficient of the mooring anchor chain, the friction coefficient between the mooring anchor chain and the seabed soil, the undrained shear strength of the seabed soil surface, the undrained shear strength gradient of the seabed soil, and the loading angle of the mooring anchor chain on the seabed surface are set to compile a subroutine for calculating the anchor chain tension and loading angle, and obtain the anchor chain tension loading angle subroutine.

[0027] Furthermore,

[0028] Step S2.2 is specifically as follows: the anchor chain tension loading angle subroutine reads the horizontal coordinates and vertical depth coordinates of the anchor chain tension application point at the current moment from the finite element model main program;

[0029] Step S2.5 is specifically as follows: the finite element model main program calculates the structural state of the large holding force anchor group system entity model at the next moment according to the applied initial value of the anchor chain tension and the loading angle, and updates the horizontal coordinates and vertical depth coordinates of the anchor chain tension application point.

[0030] Furthermore, step S2.3 is specifically as follows: setting the initial value T of the anchor chain tension L0 , and substitute the initial value of the anchor chain tension and the vertical depth coordinate of the anchor chain tension application point into the mooring anchor chain equation 1) for iterative calculation to obtain the loading angle θ L ;

[0031]

[0032] In formula (1): z L z is the vertical depth coordinate of the point where the anchor chain tension is applied; U is the vertical coordinate of the seabed surface; μ l is the friction coefficient between the mooring chain and the seabed soil, and its value range in marine clay is 0.1 to 0.6; θ U Q is the angle between the anchor chain tension on the seabed and the horizontal plane; l is the normal soil resistance per unit length of the mooring chain, and is expressed by Q l =N l qb l Calculated, where b l is the effective width of the mooring chain, N l is the bearing capacity coefficient of the mooring chain in the seabed soil, and q is the soil pressure corresponding to the buried depth of the mooring chain.

[0033] Further, step S2.6 is specifically: judging whether the dragging speed satisfies the control speed of the mooring chain dragging according to the displacement size of the mooring chain entity model in the corresponding time period, if the dragging speed is less than the control speed of the mooring chain dragging, then increasing the anchor chain tension in the anchor chain tension loading angle subprogram, if the dragging speed is greater than the control speed of the mooring chain dragging, then decreasing the anchor chain tension in the anchor chain tension loading angle subprogram, so as to maintain the dragging speed at the control speed of the mooring chain dragging.

[0034] Further, in step S2.6: the anchor chain tension adjustment value ΔT in the corresponding time period is determined by ΔT=T[v c -(Δu / Δt)] / v c , wherein T is the reference amplitude value of the anchor chain tension adjustment value, v c is the control speed of the mooring chain dragging, Δ u is the displacement of the mooring chain entity model in the last time period, Δ t is the length of the last time period.

[0035] Further, the front large holding power anchor comprises a front large holding power anchor plate, a front large holding power anchor shank is fixed on the top surface of the front large holding power anchor plate, a front mooring point is formed at the front end of the front large holding power anchor shank, the front mooring point is connected with the rear end of the mooring chain, the rear large holding power anchor comprises a rear large holding power anchor plate, a rear large holding power anchor shank is fixed on the top surface of the rear large holding power anchor plate, a rear mooring point is formed at the front end of the rear large holding power anchor shank, and the connecting piece at the rear end of the front large holding power anchor plate is connected with the rear mooring point through a connecting anchor chain.

[0036] Further, the front end left part of the front large holding power anchor plate is provided with a front first toothed plate, and the front end right part is provided with a front second toothed plate, so that the front large holding power anchor forms a front double-toothed large holding power anchor.

[0037] Further, the front end of the rear large holding power anchor plate is sequentially provided with a rear first outer toothed plate, a rear first inner toothed plate, a rear second inner toothed plate and a rear second outer toothed plate from left to right, so that the rear large holding power anchor forms a rear four-toothed large holding power anchor.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The modeling analysis method suitable for the large-grabbing anchor group system in the application can greatly simplify the modeling process of the mooring anchor chain finite element model, accurately depict the spatial form and the transmitted tension of the mooring anchor chain and the connecting anchor chain in the embedding installation process of the large-grabbing anchor group system, and is suitable for the finite element analysis of the embedding installation process of the large-grabbing anchor group system with various structural forms.

[0040] In conclusion, the application can improve the predictability of the embedding behavior of the large-grabbing anchor group system, improve the accuracy of numerical simulation, accurately depict the anchor chain tension borne by the mooring anchor chain and the spatial form and the transmitted tension of the mooring anchor chain and the connecting anchor chain in real time, reduce the complexity of the finite element model modeling, and improve the calculation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Fig. 1 is a structural schematic diagram of the large-grabbing anchor group system in the application;

[0042] Figure 2 Fig. 4 is a rigid body constraint condition schematic diagram of the connecting anchor chain body entity model;

[0043] Figure 3 Fig. 5 is a schematic diagram of the first connecting unit connecting the adjacent two connecting anchor chain body entity models;

[0044] Figure 4 Fig. 6 is a connecting mechanical property schematic diagram of the first connecting unit;

[0045] Figure 5 Fig. 7 is a flow process schematic diagram of the anchor chain tension applying process;

[0046] Figure 6 Fig. 8 is a motion trajectory curve schematic diagram of the large-grabbing anchor group system entity model.

[0047] Marked in the figure: 1, front large-grabbing anchor, 101, front large-grabbing anchor plate, 102, front large-grabbing anchor shank, 103, front mooring point, 104, connecting piece, 2, rear large-grabbing anchor, 201, rear large-grabbing anchor plate, 202, rear large-grabbing anchor shank, 203, rear mooring point, 3, mooring anchor chain, 301, mooring anchor chain body entity model, 302, fourth connecting unit, 303, anchor chain tension applying point, 4, connecting anchor chain, 401, connecting anchor chain body entity model, 402, first connecting unit, 403, connecting anchor chain body rigid reference point, 404, connecting anchor chain body binding constraint point. DETAILED DESCRIPTION

[0048] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate the present application, but not to limit the present application.

[0049] In the description of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for description purposes and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0052] A modeling analysis method suitable for a large-grab anchor group system, the large-grab anchor group system comprising a front large-grab anchor 1 and a rear large-grab anchor 2, the front end of the front large-grab anchor 1 forming a front mooring point 103, the front mooring point 103 being connected with the rear end of a mooring chain 3, the front end of the rear large-grab anchor 2 forming a rear mooring point 203, a connecting chain 4 being provided between the rear end of the front large-grab anchor 1 and the rear mooring point 203, as shown in Figure 1 ;

[0053] The modeling analysis method comprises the following steps:

[0054] S1, establishing an entity model of the large-grab anchor group system and seabed soil in the finite element model, and obtaining a finite element model main program;

[0055] S2, as shown in Figure 5 , applying the chain tension to the chain tension applying point 303 at the front end of the mooring chain entity model, specifically comprising the following steps:

[0056] S2.1, compiling a subprogram for calculating the chain tension and loading angle, to obtain a chain tension loading angle subprogram;

[0057] S2.2, the anchor chain tension loading angle subroutine reads the horizontal coordinate and vertical depth coordinate of the anchor chain tension application point 303 at the current time from the finite element model main program;

[0058] S2.3, according to the vertical depth coordinate and the initial value of the set anchor chain tension, the loading angle is obtained;

[0059] S2.4, the anchor chain tension is applied to the anchor chain tension application point 303 according to the loading angle;

[0060] S2.5, the finite element model main program calculates the structural state of the large-grabbing anchor group system entity model at the next time according to the applied anchor chain tension and loading angle, and updates the horizontal coordinate and vertical depth coordinate of the anchor chain tension application point 303;

[0061] S2.6, according to the displacement size of the mooring anchor chain entity model in the corresponding time period, it is judged whether the towing speed meets the control speed, and the anchor chain tension in the anchor chain tension loading angle subroutine is updated;

[0062] S2.7, according to the updated anchor chain tension and the updated vertical depth coordinate, the updated loading angle is obtained;

[0063] S2.8, the finite element model main program calculates and judges whether the large-grabbing anchor group system entity model is completed for towing installation, if not, repeat steps S2.4-S2.7 until the towing installation analysis is completed;

[0064] S3, monitor the horizontal displacement and vertical displacement of the front mooring point 103 and the horizontal displacement and vertical displacement of the rear mooring point 203 in the calculation process of the finite element model main program, and obtain the motion trajectory curve of the large-grabbing anchor group system entity model, see Figure 6 .

[0065] In step S1, the entity model of the large-grabbing anchor group system is established in the finite element model, which specifically includes the following steps:

[0066] S1.1, a multi-section connecting anchor chain body entity model 401 is established in the finite element model, and a rigid body condition constraint is set, a rigid reference point, i.e. a connecting anchor chain body rigid reference point 403, is set at the front end of each connecting anchor chain body entity model 401, and a binding constraint point, i.e. a connecting anchor chain body binding constraint point 404, is set at the rear end, see Figure 2; a first discrete line segment is established between two adjacent connecting anchor body entity models 401, a front end of each first discrete line segment is connected to the binding constraint point at the rear end of the former connecting anchor body entity model 401, and a rear end of each first discrete line segment is connected to the rigid reference point at the front end of the latter connecting anchor body entity model 401; connection attributes are created for each first discrete line segment, so that the length of each first discrete line segment is constant and constitutes a first connecting unit 402, see Figure 3 and Figure 4 ; each connecting anchor body entity model 401 and each first connecting unit 402 cooperates to form a connecting anchor entity model;

[0067] Among them, each connecting anchor body entity model 401 is assigned a material attribute, including the density, stiffness and Poisson's ratio of the material;

[0068] Preferably, each connecting anchor body entity model 401 is a cylindrical simplified model, a rigid reference point is set at the center point of the right end of each connecting anchor body entity model 401, and a binding constraint point is set at the center point of the left end;

[0069] S1.2, a front large grip anchor entity model is established on the front side of the connecting anchor entity model, and a rear large grip anchor entity model is established on the rear side, and a rigid condition constraint is set, a rigid reference point is set at the front mooring point 103 at the front end of the front large grip anchor entity model, and a binding constraint point is set at the connecting part at the rear end, a rigid reference point is set at the rear mooring point 203 at the front end of the rear large grip anchor entity model;

[0070] Among them, the front large grip anchor entity model and the rear large grip anchor entity model are assigned a material attribute, including the density, stiffness and Poisson's ratio of the material;

[0071] S1.3, a second discrete line segment is established with the rigid reference point at the front end of the connecting anchor entity model as an end point, a third discrete line segment is established with the binding constraint point at the rear end of the front large grip anchor entity model and the binding constraint point at the rear end of the connecting anchor entity model as end points, and the rigid reference point at the front end of the rear large grip anchor entity model is connected; connection attributes are created for the second discrete line segment and the third discrete line segment, so that the length of the second discrete line segment is constant and constitutes a second connecting unit, and so that the length of the third discrete line segment is constant and constitutes a third connecting unit;

[0072] S1.4, a plurality of mooring chain body entity models 301 are established on the front side of the front large grip anchor entity model, and rigid body condition constraints are set, a rigid reference point is set at the front end of each mooring chain body entity model 301 and a binding constraint point is set at the rear end, a fourth discrete line segment is established between two adjacent mooring chain body entity models 301, the front end of each fourth discrete line segment is connected to the binding constraint point at the rear end of the front mooring chain body entity model 301, and the rear end of each fourth discrete line segment is connected to the rigid reference point at the front end of the rear mooring chain body entity model 301, a connection attribute is created for each fourth discrete line segment, so that the length of each fourth discrete line segment is constant and constitutes a fourth connection unit 302, and the mooring chain entity model is formed by the cooperation of each mooring chain body entity model 301 and each fourth connection unit 302, wherein the rigid reference point at the front end of the mooring chain entity model forms an anchor chain tension applying point 303;

[0073] wherein, the material attribute of each mooring chain body entity model 301 is assigned, including the density, stiffness and Poisson's ratio of the material;

[0074] S1.5, a fifth discrete line segment is established with the binding constraint point at the rear end of the mooring chain entity model as an end point to connect the rigid reference point at the front end of the front large grip anchor entity model, and a connection attribute is created for the fifth discrete line segment, so that the length of the fifth discrete line segment is constant and constitutes a fifth connection unit.

[0075] wherein, step S2.1 is specifically: according to the geometric characteristics of the mooring chain entity model, setting the effective width of the mooring chain bearing, the bearing coefficient of the mooring chain in the seabed soil, the friction coefficient between the mooring chain and the seabed soil, the undrained shear strength of the seabed surface soil of the seabed soil, the undrained shear strength gradient of the seabed soil, the angle between the anchor chain tension and the horizontal plane at the seabed surface of the mooring chain, to compile a subprogram for calculating the anchor chain tension and the loading angle, and obtain the anchor chain tension loading angle subprogram.

[0076] Preferably, the effective width of the mooring chain bearing is 0.2m, the bearing coefficient of the mooring chain in the seabed soil is 10, the friction coefficient between the mooring chain and the seabed soil is 0.2, the undrained shear strength of the seabed surface soil of the seabed soil is 6kPa, the undrained shear strength gradient of the seabed soil is 1.5kPa / m, and the angle between the anchor chain tension and the horizontal plane at the seabed surface of the mooring chain is 0°.

[0077] wherein, step S2.3 is specifically: setting the initial value T L0 of the anchor chain tension, and substituting the initial value T L0 of the anchor chain tension and the vertical depth coordinate of the anchor chain tension applying point 303 into the mooring chain equation 1 to iteratively calculate the loading angle θ L ;

[0078]

[0079] in formula 1) : z L is the vertical depth coordinate of the anchor chain tension application point 303; z U is the vertical coordinate of the seabed surface; μ l is the friction coefficient between the mooring chain and the seabed soil, which is in the range of 0.1-0.6 in marine clay; θ U is the angle between the anchor chain tension and the horizontal plane at the seabed surface; Q l is the normal soil resistance per unit length of the mooring chain, which is determined by Q l = N l qb l is calculated, wherein b l is the effective width of the mooring chain, N l is the bearing coefficient of the mooring chain in the seabed soil, and q is the soil pressure corresponding to the buried depth of the mooring chain.

[0080] Preferably, T L0 = 5000 kN.

[0081] In step S2.6, the displacement of the mooring chain entity model in the corresponding time period is determined, and the displacement is compared with the control speed of the mooring chain 3 to determine whether the towing speed meets the control speed of the mooring chain 3. If the towing speed is less than the control speed of the mooring chain 3, the anchor chain tension in the anchor chain tension loading angle subroutine is increased. If the towing speed is greater than the control speed of the mooring chain 3, the anchor chain tension in the anchor chain tension loading angle subroutine is decreased, so that the towing speed is maintained at the control speed of the mooring chain 3.

[0082] Preferably, in step S2.6, the anchor chain tension adjustment value ΔT in the corresponding time period is determined by ΔT = T[v c -(Δu / Δt)] / v c , wherein T is the reference amplitude of the anchor chain tension adjustment value, v c is the control speed of the mooring chain 3, Δ u is the displacement of the mooring chain entity model in the previous time period, and Δ t is the length of the previous time period. Preferably, v c is 1 times the length of the anchor plate of the previous large holding force anchor 1 per second, and T is 1 kN.

[0083] The front large-grabbing anchor 1 comprises a front large-grabbing anchor plate 101, and a front large-grabbing anchor shank 102 is fixed to the top surface of the front large-grabbing anchor plate 101; the front end of the front large-grabbing anchor shank 102 forms a front mooring point 103, and the front mooring point 103 is connected with the rear end of the mooring anchor chain 3; the rear large-grabbing anchor 2 comprises a rear large-grabbing anchor plate 201, and a rear large-grabbing anchor shank 202 is fixed to the top surface of the rear large-grabbing anchor plate 201; the front end of the rear large-grabbing anchor shank 202 forms a rear mooring point 203, and the connecting piece 104 at the rear end of the front large-grabbing anchor plate 101 is connected with the rear mooring point 203 through the connecting anchor chain 4.

[0084] Preferably, the front end of the front large-grabbing anchor plate 101 is provided with a front first toothed plate at the left part and a front second toothed plate at the right part, so that the front large-grabbing anchor 1 forms a front double-toothed large-grabbing anchor.

[0085] Preferably, the front end of the rear large-grabbing anchor plate 201 is sequentially provided with a rear first outer toothed plate, a rear first inner toothed plate, a rear second inner toothed plate and a rear second outer toothed plate from left to right, so that the rear large-grabbing anchor 2 forms a rear four-toothed large-grabbing anchor.

[0086] In the present application, by establishing a plurality of mooring anchor chain body entity models 301, the loading angle at the anchor chain tension application point 303 at the front end of the mooring anchor chain entity model is calculated by using the mooring anchor chain equation, the anchor chain tension is applied to the anchor chain tension application point 303, instead of the finite element modeling of the complete mooring anchor chain 3, the modeling length of the finite element model of the mooring anchor chain 3 is greatly reduced, and the overall calculation cost of the model is greatly reduced, the anchor chain tension is transmitted through the connecting anchor chain entity model, the drag force is applied to the large-grabbing anchor group system entity model, the modeling and calculation efficiency of the finite element model is improved under the premise of retaining the spatial form, force transmission characteristics and calculation accuracy of the mooring anchor chain 3 and the connecting anchor chain 4 in the dragging process, and the accurate motion trajectory curve of the large-grabbing anchor group system entity model is obtained.

[0087] In summary, the present application not only simplifies the complexity of the finite element modeling process of the mooring anchor chain 3 in the large-grabbing anchor group system and improves the modeling efficiency, but also retains the spatial form and force transmission characteristics of the connecting anchor chain 4 and the mooring anchor chain 3 in the dragging process, realizes the dynamic application of the anchor chain tension in the large-grabbing anchor group system entity model dragging installation process, avoids the use of constant anchor chain tension to replace the dynamic anchor chain tension, and provides an effective numerical simulation prediction method for predicting the complex embedding behavior and motion trajectory of the large-grabbing anchor group system in the seabed.

[0088] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and replacements without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A modeling and analysis method for a high-holding force anchor system, characterized in that: The high-holding power anchor system comprises a front high-holding power anchor (1) and a rear high-holding power anchor (2), wherein the front end of the front high-holding power anchor forms a front mooring point (103), the front mooring point (103) is connected to the rear end of a mooring anchor chain (3), the front end of the rear high-holding power anchor (2) forms a rear mooring point (203), and a connecting anchor chain (4) is provided between the rear end of the front high-holding power anchor (1) and the rear mooring point (203); The modeling analysis method includes the following steps: S1. Establishing a solid model of the high-holding anchor system and seabed soil in the finite element model, and obtaining the finite element model main program; S2, applying anchor chain tension to the anchor chain tension application point (303) at the front end of the mooring anchor chain physical model, specifically comprising the following sub-steps: S2.

1. Prepare a subroutine to calculate the anchor chain tension and loading angle, and obtain the anchor chain tension and loading angle subroutine; S2.2, the anchor chain tension loading angle subroutine reads the vertical depth coordinate of the anchor chain tension application point (303) at the current moment from the finite element model main program; S2.

3. Obtain the loading angle based on the vertical depth coordinate and the set initial value of the anchor chain tension; S2.

4. Apply anchor chain tension to the anchor chain tension application point (303) according to the loading angle; S2.5, the finite element model main program calculates the structural state of the large holding force anchor group system entity model at the next moment according to the applied anchor chain tension and loading angle, and updates the vertical depth coordinate of the anchor chain tension application point (303); S2.

6. Determine whether the towing speed meets the control speed based on the displacement of the mooring anchor chain entity model within the corresponding time period, and update the anchor chain tension in the anchor chain tension loading angle subroutine; S2.

7. Obtain an updated loading angle based on the updated anchor chain tension and the updated vertical depth coordinate; S2.

8. The finite element model main program calculates and determines whether the drag installation of the high-holding force anchor system solid model has been completed. If not, steps S2.4-S2.7 are repeated until the drag installation analysis is completed. S3. During the calculation process of the finite element model main program, the horizontal displacement and vertical displacement of the front mooring point (103) and the horizontal displacement and vertical displacement of the rear mooring point (203) are monitored to obtain a motion trajectory curve of the large holding force anchor group system entity model.

2. A modeling and analysis method for a high-holding force anchor system according to claim 1, characterized in that: In step S1, a solid model of the high-holding force anchor system is established in the finite element model, which specifically includes the following sub-steps: S1.

1. Establishing a multi-segment anchor chain entity model (401) in a finite element model, and setting rigid body condition constraints, setting a rigid body reference point at the front end of each segment of the anchor chain entity model (401) and setting a binding constraint point at the rear end; establishing a first discrete line segment between two adjacent segments of the anchor chain entity model (401), with the front end of each first discrete line segment connected to the binding constraint point at the rear end of the front segment of the anchor chain entity model (401), and the rear end of each first discrete line segment connected to the rigid body reference point at the front end of the rear segment of the anchor chain entity model (401); creating connection attributes for each segment of the first discrete line segment, so that the length of each segment of the first discrete line segment is constant and constitutes a first connection unit (402); each segment of the anchor chain entity model (401) and each segment of the first connection unit (402) cooperate to form the anchor chain entity model; S1.

2. Establishing a front high-holding anchor entity model at the front side of the connecting anchor chain entity model and establishing a rear high-holding anchor entity model at the rear side, and setting rigid body condition constraints, setting a rigid body reference point at the front mooring point (103) at the front end of the front high-holding anchor entity model and setting a binding constraint point at the connection part at the rear end, and setting a rigid body reference point at the rear mooring point (203) at the front end of the rear high-holding anchor entity model; S1.

3. Establish a second discrete line segment with the rigid reference point connected to the front end of the anchor chain entity model as an endpoint, connecting the binding constraint point at the rear end of the front high-holding-power anchor entity model. Establish a third discrete line segment with the binding constraint point connected to the rear end of the anchor chain entity model as an endpoint, connecting the rigid reference point at the front end of the rear high-holding-power anchor entity model. Create connection attributes for the second discrete line segment and the third discrete line segment, such that the length of the second discrete line segment is constant and constitutes a second connection unit, and the length of the third discrete line segment is constant and constitutes a third connection unit. S1.

4. Establishing multiple mooring chain entity models (301) at the front side of the front large holding force anchor entity model, and setting rigid body condition constraints, setting a rigid body reference point at the front end of each mooring chain entity model (301) and a binding constraint point at the rear end; establishing a fourth discrete line segment between two adjacent mooring chain entity models (301), the front end of each fourth discrete line segment being connected to the binding constraint point at the rear end of the front mooring chain entity model (301), and the rear end of each fourth discrete line segment being connected to the rigid body reference point at the front end of the rear mooring chain entity model (301); creating connection attributes for each fourth discrete line segment, so that the length of each fourth discrete line segment is constant and constitutes a fourth connection unit (302); each mooring chain entity model (301) and each fourth connection unit (302) cooperate to form a mooring chain entity model, wherein the rigid body reference point at the front end of the mooring chain entity model forms an anchor chain tension application point (303); S1.

5. Establish a fifth discrete line segment with the binding constraint point at the rear end of the mooring anchor chain solid model as the endpoint to connect to the rigid reference point at the front end of the front high-holding anchor solid model; create connection attributes for the fifth discrete line segment so that the length of the fifth discrete line segment is constant and constitutes a fifth connection unit.

3. The modeling and analysis method for a high-holding force anchor system according to claim 1, characterized in that: Step S2.1 is specifically as follows: according to the geometric characteristics of the mooring anchor chain entity model, the effective width of the mooring anchor chain bearing, the bearing coefficient of the mooring anchor chain in the seabed soil, the friction coefficient between the mooring anchor chain and the seabed soil, the undrained shear strength of the seabed soil surface, the undrained shear strength gradient of the seabed soil, and the angle between the anchor chain tension exerted on the mooring anchor chain at the seabed surface and the horizontal plane are set to compile a subroutine for calculating the anchor chain tension and loading angle, and obtain the anchor chain tension loading angle subroutine.

4. The modeling and analysis method for a high-holding force anchor system according to claim 1, characterized in that: Step S2.2 is specifically as follows: the anchor chain tension loading angle subroutine reads the horizontal coordinates and vertical depth coordinates of the anchor chain tension application point (303) at the current moment from the finite element model main program; Step S2.5 is specifically as follows: the finite element model main program calculates the structural state of the large holding force anchor group system entity model at the next moment according to the applied anchor chain tension initial value and loading angle, and updates the horizontal coordinate and vertical depth coordinate of the anchor chain tension application point (303).

5. The modeling and analysis method for a high-holding force anchor system according to claim 1, characterized in that: Step S2.3 is as follows: Set the initial value of the anchor chain tension T L0 , and substitute the initial value of the anchor chain tension and the vertical depth coordinate of the anchor chain tension application point (303) into the mooring anchor chain equation 1) and iteratively calculate to obtain the loading angle θ L ; In formula 1), z L z is the vertical depth coordinate of the anchor chain tension application point (303); U is the vertical coordinate of the seabed surface; μ l is the friction coefficient between the mooring chain and the seabed soil, and its value range in marine clay is 0.1 to 0.6; θ U Q is the angle between the anchor chain tension on the seabed and the horizontal plane; l is the normal soil resistance per unit length of the mooring chain, and is expressed by Q l =N l qb l Calculated, where b l is the effective width of the mooring chain, N l is the bearing coefficient of the mooring chain in the seabed soil, and q is the soil pressure corresponding to the buried depth of the mooring chain.

6. The modeling and analysis method for a high-holding force anchor system according to claim 1, characterized in that: Step S2.6 is specifically as follows: according to the displacement size of the mooring anchor chain entity model in the corresponding time period, it is judged whether the towing speed meets the control speed of the mooring anchor chain (3) towing; if the towing speed is less than the control speed of the mooring anchor chain (3), the anchor chain tension in the anchor chain tension loading angle subroutine is increased; if the towing speed is greater than the control speed of the mooring anchor chain (3), the anchor chain tension in the anchor chain tension loading angle subroutine is reduced to maintain the towing speed at the control speed of the mooring anchor chain (3).

7. A modeling and analysis method for a high-holding force anchor system according to claim 6, characterized in that: In step S2.6: the anchor chain tension adjustment value ΔT in the corresponding time period is calculated by ΔT=T[v c -(Δu / Δt)] / v c Determine, where T is the reference amplitude of the anchor chain tension adjustment value, v c is the controlled speed of the mooring chain (3) dragging, Δu is the displacement of the mooring chain entity model in the previous time period, Δ t The length of the previous time period.

8. The modeling and analysis method for a high-holding-force anchor system according to claim 1, characterized in that: The front high-holding power anchor (1) comprises a front high-holding power anchor plate (101), a front high-holding power anchor shank (102) is fixed on the top surface of the front high-holding power anchor plate (101), the front end of the front high-holding power anchor shank (102) forms a front mooring point (103), and the front mooring point (103) is connected to the rear end of a mooring anchor chain (3); the rear high-holding power anchor (2) comprises a rear high-holding power anchor plate (201), a rear high-holding power anchor shank (202) is fixed on the top surface of the rear high-holding power anchor plate (201), the front end of the rear high-holding power anchor shank (202) forms a rear mooring point (203), and a connecting piece (104) at the rear end of the front high-holding power anchor plate (101) is connected to the rear mooring point (203) via a connecting anchor chain (4).

9. The modeling and analysis method for a high-holding-force anchor system according to claim 8, characterized in that: The front high-holding power anchor plate (101) is provided with a front first tooth plate at the left front end and a front second tooth plate at the right front end, so that the front high-holding power anchor (1) forms a front double-tooth high-holding power anchor.

10. The modeling and analysis method for a high-holding-force anchor system according to claim 8, characterized in that: The front end of the rear high-holding power anchor plate (201) is provided with a rear first outer tooth plate, a rear first inner tooth plate, a rear second inner tooth plate and a rear second outer tooth plate in sequence from left to right, so that the rear high-holding power anchor (2) forms a rear four-tooth high-holding power anchor.

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