CN208149556U - A kind of novel light power installation anchor - Google Patents

Abstract

The utility model belongs to the technical field of ocean engineering, and relates to a novel lightweight dynamic installation anchor. It is mainly composed of wing plate, anchor handle and connecting rod; the wing plate is composed of two triangular flat plates symmetrically spliced, and the connecting rod is installed at the tail of the wing plate; the anchor handle is an inverted V-shaped structure composed of two trapezoidal flat plates, symmetrically fixed on the on the wing. The propeller can be fixed on the tail of the new lightweight power anchor through the shear pin, and the combination of the new lightweight power installation anchor, the propeller and the shear pin is installed to form a combined anchor; the combined anchor is released into the seawater, and the anchor chain is loosened. Make the combination anchor penetrate into the soil; install the anchor chain tensioned, the shear pin is sheared, the thruster is pulled out, while the new lightweight power installation anchor stays in the soil; the working anchor chain is tensioned to adjust the new lightweight power installation Angle of the anchor; thruster removed for installation of the next new lightweight power-mounted anchor. The utility model has the advantages of light weight, high bearing efficiency, improved sinking depth of the anchor in the soil, and reduced cost.

Description

A New Type of Lightweight Dynamic Mounting Anchor

technical field

The utility model belongs to the technical field of ocean engineering, and relates to a novel lightweight dynamic installation anchor.

Background technique

With the rapid development of social economy and the gradual depletion of land and shallow sea oil and gas resources, people gradually shift the development of oil and gas resources to deep sea. In the deep-sea environment with a water depth of more than 300-500m, oil and gas exploration, acquisition and storage equipment are mainly connected to the anchorage foundation acting on the seabed surface or embedded in the seabed through the anchor chain system. Therefore, the anchor foundation is the root of the mooring system and the prerequisite for the safe operation of the superstructure. Anchoring foundations suitable for deep-sea mooring systems mainly include suction caissons, dragging anchors, suction mounting plate anchors and dynamic mounting anchors. Suction caissons are installed by pumping water from a valve at the top of the caisson to create a negative pressure inside the caisson, thereby pushing the caisson to the desired depth in the seabed. When installing a towed anchor, a tugboat is needed to drag the anchor from the surface of the seabed to a certain depth in the seabed. Suction mounting plate anchor needs to be installed with the help of suction caisson. After the installation, pull out the caisson, and then tension the anchor chain to make the anchor turn to the angle required by the working state. The dynamic installation anchor does not need to rely on external force during installation, relying on the kinetic energy obtained by the free fall of the anchor in the water and the potential energy of its own gravity to penetrate into the soil to a certain depth, and relying on the anchoring force of the surrounding soil to provide the uplift bearing capacity. Therefore, compared with the first three kinds of anchor foundations, the dynamic installation anchor has the advantages of short installation time and low installation cost, so it has broad development prospects in marine engineering.

The dynamic anchors currently used in practical engineering are mainly torpedo anchors (US Patent, Patent No. 6106199) and multi-directional loaded anchors (US Patent, Patent No. 7059263, B1). The torpedo anchor consists of a cylindrical central shaft with a semi-ellipsoidal or conical front end and several fins. The central shaft is used to provide the weight of the anchor so that the anchor can penetrate into the soil without external force. Improves the directional stability of anchors when falling through water. However, since the anchor hole is located at the uppermost end of the anchor axis, the uplift bearing capacity of the anchor is mainly provided by the friction force on the anchor-soil contact surface when the uplift load is applied, so the bearing efficiency of the anchor is low. The multi-loaded anchor is composed of three flat plates with an angle of 120° to each other. The surface area of the anchor is large, which increases the contact area between the anchor and the surrounding soil. Rotation will occur during the time, thereby increasing the projected area of the anchor perpendicular to the uplift load direction to increase the uplift bearing capacity. However, multi-loaded anchors are light in weight and large in surface area, resulting in limited penetration depth of the anchor in the soil. Seabed soft clay is generally normal consolidated soil or slightly overconsolidated soil, and the soil strength increases linearly with depth, so the smaller the installation depth of the anchor, the smaller the corresponding uplift bearing capacity.

The utility model absorbs the advantages of the dynamic anchor, and proposes a novel light-weight deep penetrating plate anchor (L-DPPA). The anchor is mainly composed of a wing plate, an anchor handle and an anchor eye. The wing plate consists of two triangular flat plates, which increase the anchor-soil contact area, thereby improving the bearing capacity. In order to increase the penetration depth of the anchor in the seabed, the anchor needs to be installed with the help of a propeller. The thruster is mainly composed of a cylindrical central shaft, fin and anchor eye, which can be connected to the tail of the anchor to increase the penetration speed and penetration depth of the anchor. After the installation is completed, the thruster can be recovered for the installation of the next anchor . By adjusting the size of the anchor and the weight of the propeller, the anchor can be applied to seabeds of various strengths and soils (including clay and sandy soil).

Utility model content

In order to solve the above problems, the utility model proposes a new type of lightweight dynamic installation anchor, including a new type of lightweight dynamic installation anchor (L-DPPA) and a power installation method for installing the anchor by means of a propeller.

Technical scheme of the utility model:

A new type of lightweight dynamic installation anchor, mainly composed of a wing plate 11, an anchor handle 12 and a connecting rod 14; the wing plate 11 is composed of two triangular flat plates symmetrically spliced, and the angle between the two is adjusted according to engineering requirements Two triangular flat plates of the wing plate 11 are symmetrically provided with a plurality of openings a15; the connecting rod 14 is installed on the afterbody of the wing plate 11, and the connecting rod 14 is provided with the opening b17, which is connected by the shear pin 3 The rod 14 is fixedly connected with the propeller 2; the anchor handle 12 is an inverted V-shaped structure composed of two trapezoidal flat plates, and the bottom of the anchor handle 12 is provided with a plurality of openings c18, and the opening c18 and the opening a15 cooperate with each other. The anchor handle 12 is symmetrically fixed on the two triangular flat plates of the wing plate 11 by the bolt 16; the top of the anchor handle 12 is provided with an anchor eye 13, which is used to connect the working anchor chain 5 to provide the pull-out bearing capacity; by adjusting the anchor handle 12 fixed position, the anchor handle 12 moves up and down along the axial direction of the wing plate 11, thereby changing the offset of the anchor eye 13, that is, the projection of the distance from the anchor eye 13 to the soil resistance center of the wing plate 11 in the axial direction of the wing plate 11 , so that the new lightweight dynamic installation anchor has the performance of diving when it is subjected to an uplift load, and the new lightweight dynamic installation anchor is embedded in the soil layer to obtain bearing capacity.

An installation method of a new type of lightweight dynamic installation anchor. The installation anchor chain 4 is connected to the anchor eye 23 of the propeller; Mass power installation anchor 1, propeller 2 and shear pin 3 are combined and installed to form a combined anchor; the working anchor chain 5 is connected to the anchor eye 13;

Specific steps are as follows:

First release the combination anchor into the seawater, make the combination anchor above the seabed surface, then loosen and install the anchor chain 4, make the combination anchor fall freely in the water, and rely on the kinetic energy obtained by the free fall and the gravity potential energy of the combination anchor itself to penetrate into the soil After the installation, the installation anchor chain 4 at the tail of the thruster 2 is tensioned. When the shear force received by the shear pin 3 is greater than its own allowable shear force, the shear pin 3 is sheared, so that the propeller 2 is pull out, while the new lightweight dynamic installation anchor 1 remains in the soil; tension the working anchor chain 5, when the force transmitted by the working anchor chain 5 to the anchor eye 13 exceeds the initial pull-out bearing capacity of the new lightweight dynamic installation anchor 1 At this time, the new lightweight dynamic installation anchor 1 starts to move in the soil to adjust the angle of the new lightweight dynamic installation anchor 1; after the propeller 2 is taken out, it is used for the installation of the next new lightweight dynamic installation anchor.

The permissible shear force of the shear pin 3 is 1.5-2.0 times the weight of the new lightweight dynamic installation anchor 1 .

The weight of the propeller 2 is adjusted according to actual engineering needs, so that the anchor can penetrate into seabeds of different strengths and soil properties.

The propeller 2 adopts the propeller in the patent application No. 201610648708.7, which is mainly composed of a propeller central axis 21, a propeller empennage 22 and a propeller anchor eye 23; the front end of the propeller central axis 21 is provided with a transverse The opening 24 at the front end of the central shaft of the propeller and the slot 25 at the front end of the central shaft of the longitudinal propeller, the opening 24 at the front end of the central shaft of the propeller is used to place the shear pin 3, and the slot 25 at the front end of the central shaft of the propeller is used to connect the new light The connecting rod 14 of the mass power installation anchor 1; the opening 24 at the front end of the central axis of the propeller is coaxial with the opening b17 on the connecting rod 14 and cooperates with each other;

The propeller empennage 22 is installed on the afterbody of the propeller central axis 21, and the center of the propeller central axis 21 tail is provided with a propeller anchor eye 23 for connecting and installing the anchor chain 4; the width and number of the propeller empennage 22 Increase or decrease according to actual needs to ensure the directional stability of the whole body when it falls in water.

The central axis 21 of the propeller is a hollow cylinder, the tail is a gradually shrinking circular platform, and the front end is semi-ellipsoidal or hemispherical; the material filled inside the hollow cylinder is mercury, lead or concrete.

The material of the propeller empennage 22 is alloy material, composite material or plastic, and the position of the center of gravity is lowered by reducing the density of the propeller empennage 22 .

Beneficial effects of the utility model: the new lightweight dynamic installation anchor proposed in the utility model has the advantages of light weight, high load-bearing efficiency, and can dive under appropriate conditions. In addition, the dynamic installation method of anchor installation with the aid of propellers proposed in the utility model can significantly increase the sinking depth of the anchor in the soil, so as to adapt to different soil properties and soil strengths. Although installing the anchor of the utility model by means of a propeller increases the installation cost to a certain extent, the load-bearing efficiency of a single anchor is significantly improved. The installation of all anchors is done with one pusher, thereby saving production costs. Therefore, the number of anchors required by the entire mooring system can be reduced, and the production, transportation and installation costs can be reduced, thereby reducing the total cost of the project. The anchor and installation method in the utility model are not affected by water depth, have wide applicability, and can be used for anchoring foundations of marine floating platforms, floating fans, and the like. The utility model is helpful to promote the development process of my country's deep-sea mooring system anchoring foundation.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of the novel lightweight dynamic installation anchor in the utility model.

Fig. 2 is the front view of the novel lightweight power installation anchor in the utility model.

Fig. 3 is a side view of the novel lightweight dynamic installation anchor in the utility model.

Fig. 4 is a top view of the new lightweight dynamic installation anchor in the utility model.

Fig. 5 is a three-dimensional schematic diagram of the propeller in the utility model.

Fig. 6 is the front view of the propeller in the utility model.

Fig. 7 is a side view of the propeller in the utility model.

Fig. 8 is a top view of the propeller in the utility model.

Figure 9 is a schematic diagram of the novel lightweight power-mounted anchor and thruster connection.

Fig. 10 is an installation flow diagram of the installation of the new lightweight power installation anchor by means of a propeller.

Fig. 11(a) is the prediction result of the dynamic penetration process of the new lightweight dynamic installation anchor and composite anchor in soil.

Fig. 11(b) is a schematic diagram of the variation curve of the velocity of the composite anchor with depth at different penetration velocities.

In the figure: 1 new lightweight power installation anchor; 2 propeller; 3 shear pin; 4 installation anchor chain; 5 working anchor chain; 11 wing plate; 12 anchor handle; ; 16 bolts; 17 hole b; 18 hole c; 2 propeller; 21 propeller central shaft; 22 propeller empennage; 23 propeller anchor eye; Grooving.

Detailed ways

Below in conjunction with accompanying drawing and technical scheme, further illustrate the specific embodiment of the utility model.

1. New lightweight power anchor

Figures 1-4 are schematic diagrams of the new lightweight dynamic installation anchor 1, which is mainly composed of a wing plate 11, an anchor handle 12 and a connecting rod 14. The wing plate 11 is composed of two triangular flat plates symmetrically spliced together, and the dimensions of the two right-angled sides of the triangular flat plate can be adjusted according to actual conditions to adapt to different soil strengths and soil properties. Two triangular flat plates can be connected by welding, riveting, hinged and other processing techniques to form the wing plate 11 . The angle between the two triangular flat plates is greater than 180°, which is to balance the eccentricity caused by the anchor handle 12 . The angle between the two triangular plates is determined according to the size of the wing plate 11 and the anchor handle 12, so that the center of gravity of the anchor falls on the axis X-X of the anchor, as shown in Figure 1. The front end of the wing plate 11 forms a sharp point, which reduces the soil resistance suffered by the anchor when it is initially penetrated into the soil, and helps the anchor to obtain a deeper penetration depth. In addition, according to the needs of processing or transportation, the three vertices of the wing plate 11 can be processed into a shape with a certain radian, so as to reduce the wear and buckling damage of the anchor during transportation.

The anchor handle 12 is mainly composed of two trapezoidal flat plates, and the top of the anchor handle 12 is opened to form an anchor eye 13 . The working anchor chain 5 is drawn out from the anchor eye 13, and the upper load acts on the novel lightweight power installation anchor 1 through the working anchor chain 5. When the installation of the new lightweight dynamic installation anchor 1 is completed, the initial axis direction of the new lightweight dynamic installation anchor 1 is the vertical direction. Then the working anchor chain 5 is tensioned, and when the force delivered by the working anchor chain 5 to the anchor eye 13 exceeds the initial pull-out capacity of the new lightweight dynamic installation anchor 1, the new lightweight dynamic installation anchor 1 begins to move in the soil. Since the point of action of the uplift load is located at the anchor hole 13 rather than the tail of the wing plate 11 , the uplift load will form a moment on the center of the soil resistance of the wing plate 11 . The resistance central point of the soil body refers to when the anchor moves tangentially (movement along the X-X axis direction) or normal motion (perpendicular to the plane direction formed by the three vertices of the wing plate 11), the resistance of the soil body to the point The torque value is zero. The distance from the anchor eye 13 to the axis of the wing plate 11 can be adjusted according to actual engineering needs, and this distance is also called the anchor eye eccentricity. Under the action of the moment formed by the uplift load relative to the center of resistance of the soil, the anchor will rotate in the soil. The position of the anchor tip will rotate towards the initial position of the anchor hole, while the anchor tail will rotate away from the initial position of the anchor hole. With the rotation of the anchor, the projected area of the wing plate 11 perpendicular to the uplift load direction increases, thereby increasing the normal bearing capacity. Therefore, compared with the torpedo anchor, the new lightweight dynamic installation anchor 1 of the utility model is mainly subjected to the normal force of the soil instead of the tangential force in the soil, so it has a higher load-bearing efficiency, that is, the pull-out resistance of the anchor The ratio of bearing capacity to anchor weight is high. The larger the eccentricity of the anchor hole, the smaller the buried depth loss during the rotation of the anchor plate.

The bottom of the anchor handle 12 is connected to the wing plate 11 by a bolt 16 . The bottom of the anchor handle 12 is provided with an opening c18, and the wing plate 11 is also provided with a matching opening a15. The wing plate 11 and the anchor handle 12 are connected by bolts 16, as shown in FIG. 1 . In addition, other methods, such as anchoring with rivets, can also be used to fix the wing plate 11 and the anchor handle 12 . In the utility model, the position of the anchor handle 12 can be adjusted along the X-X axis direction, thereby changing the position of the anchor hole 13 relative to the resistance center of the soil. The projection of the distance from the anchor eye 13 to the resistance center of the soil in the direction of the X-X axis is called the anchor eye offset. The offset of the anchor hole is the key factor to determine whether the anchor has a submerged property when it is subjected to an uplift load. Under the right circumstances, the anchor will dive deeper into the soil when subjected to an uplift load, resulting in a higher uplift capacity. Therefore, the position of the anchor handle 12 on the wing plate 11 can be determined according to the actual engineering needs and the soil quality and strength of the soil on site.

A connecting rod 14 is provided at the tail of the wing plate 11, and there is an opening b17 on the connecting rod, as shown in FIG. 2 . The function of the connecting rod 14 and the opening b17 is introduced in detail in the propeller part.

2. Thruster

5-8 are schematic diagrams of the thruster 2 . The propeller 2 is mainly composed of a propeller axis 21, a propeller empennage 22 and a propeller anchor eye 23. The central axis 21 of the propeller is a cylindrical structure, and the front end is designed to be semi-ellipsoidal or hemispherical, which can make the water flow evenly transition around the front end of the central axis of the propeller, so as to reduce the drag resistance of the propeller when it falls in the water, thereby improving Penetration speed: the tail of the thruster central shaft 21 is designed into a gradually shrinking cone shape, which can make the water flow through the tail of the propeller smoothly, reduce the vortex area, and increase the penetration speed. The shape of the thruster central shaft 21 is similar to streamlined, which is to reduce the drag resistance of the propeller 2 in water, thereby helping the new light-weight power installation anchor 1 to obtain higher penetration speed and deeper penetration depth . The diameter and length of the propeller shaft 21 can be adjusted according to the soil quality and soil strength on site. When the soil strength is high, it is recommended to lengthen the length of the propeller or increase the diameter of the propeller to increase the weight of the propeller and help the anchor reach the depth required by the design. In addition, the central shaft 21 of the propeller can be made hollow, filled with denser materials such as lead and mercury in the middle, so as to increase the density and quality of the propeller and improve the penetration depth of the anchor in the soil.

The propeller empennage 22 is used to improve the directional stability of the combined anchor when it falls in water. Empennage 22 shown in Fig. 5 has three slices, each other becomes 120 °. According to actual needs, the number, shape and size of the empennage can be adjusted to meet the needs of different projects. When the anchor is falling in the water, the lower the center of gravity, that is, the closer the center of gravity is to the anchor tip, the better the directional stability of the anchor in the water. Good directional stability of the anchor means that when the anchor falls in the water, the direction of the axis of the anchor will not deviate from the vertical direction. straight direction. Therefore, in addition to lowering the center of gravity by filling the propeller center shaft 21 with a material with a higher density as described above, the position of the center of gravity can also be lowered by reducing the density of the empennage 22 . The empennage 22 can be made of lighter materials, such as high-strength alloy materials, composite materials, high-strength plastics, and the like.

The front end of the propeller shaft 21 is provided with a longitudinal slot 25 at the front end of the propeller shaft, as shown in FIG. 7 . The slot 25 at the front end of the central shaft of the propeller matches the connecting rod 14, which can ensure that the connecting rod 14 is just inserted into the slot 25 at the front end of the central shaft of the propeller. At this time, the opening b17 on the connecting rod 14 of the novel lightweight power installation anchor 1 is coaxial with the opening 24 at the front end of the central axis of the propeller. Use the shear pin 3 to pass through the opening b17 and the opening 24 at the front end of the central axis of the thruster, so that the anchor 1 and the thruster 2 are installed with a new type of lightweight power, as shown in FIG. 9 . The allowable shear force of the shear pin 3 should be about 1.5–2.0 times the weight of the anchor 1, so that it can not only ensure that the new light-weight dynamic installation anchor 1 will not break away from the propeller 2 when the combined anchor is released in the water, but also ensure that after the installation is completed, When the propeller 2 is pulled out, the shear pin 3 can be cut off in time without pulling out the new light-weight power installation anchor 1 .

The propeller anchor eye 23 is used to tie and install the anchor chain 4 . The installation anchor chain 4 is also used to recover the thruster after the installation is completed. After the combined anchor installation is completed, the anchor chain 4 is tensioned and installed, and the propeller 2 can be pulled out from the soil, leaving only the anchor in the soil.

3. Installation method

Fig. 10 shows the power installation process of using the propeller 2 to install the anchor 1. First, the shear pin 3 is used to connect the new lightweight power installation anchor 1 and the propeller 2 to form a combined anchor. Then release the combination anchor from the installation ship to a certain height from the seabed surface, waiting for installation. Trigger the switch on the installation anchor chain 4 to make the combined anchor fall in the water to obtain kinetic energy, and rely on the kinetic energy obtained by the combined anchor moving in the water and its own gravity potential energy to penetrate into the soil to complete the installation. After the installation is finished, the anchor chain 4 is tensioned and installed, and the propeller 2 is pulled out of the seabed after the shear pin 3 is cut off, leaving only the new lightweight power installation anchor 1 in the seabed. Then the working anchor chain 5 connected to the anchor hole 13 is tensioned with a tugboat at a certain pulling angle, so that the new light-weight dynamic installation anchor 1 is rotated to a certain angle from the vertical direction, thereby providing the pull-out bearing capacity. Thruster 2 can be used for the installation of the next anchor.

4. Verification of utility model design

In order to verify the practicability of the new dynamic anchor proposed by the utility model and the dynamic installation method for installing the anchor with the help of a propeller, the working performance and working performance of the anchor are studied respectively from the two stages of the anchor falling in the water and the power penetration in the soil. efficiency.

a. Hydrodynamic properties

When the combined anchor falls freely in the water, it will be dragged by the water. The drag resistance of water to the anchor can be expressed by formula (1).

In the formula, F _D,w is the drag resistance of water to the anchor, C _D,w is the drag coefficient, ρ _w is the density of water, A _F is the projected area of the anchor in the direction perpendicular to the axis. It can be seen from formula (1) that the drag resistance is proportional to the square of the speed. As the anchor's falling speed increases, the drag resistance increases rapidly, and when the drag resistance is equal to the effective weight of the anchor in the water, the acceleration of the anchor decreases to zero. The corresponding speed at this time is called the ultimate speed of the anchor, v _T . The expression of the anchor's limit speed is shown in formula (2).

In the formula, W _A ′ is the effective weight of the anchor in water.

Table 1 Main parameters of anchor and thruster

The hydrodynamic characteristics of the anchor in the process of falling in the water include the anchor drag coefficient, ultimate velocity, directional stability, etc. Based on the fluid dynamics software FLUENT 17.0, the utility modeler studied the hydrodynamic characteristics of the composite anchor in water. The relevant dimensions of anchors and propellers are shown in Table 1. The numerical calculation results show that the orientation of the composite anchor is very good. Once the axis direction of the anchor deviates from the vertical direction, the anchor will gradually adjust to make the axis direction return to the vertical direction. In addition, the numerical calculation results show that when the combined anchor falls freely in water, the corresponding drag coefficient is 0.71, and the limit speed is 33.5m/s.

b. Penetration depth of the anchor in the soil

The following is the use of theoretical analysis methods to predict the penetration depth of the new dynamic installation anchor in the soil. The main dimensions of anchors and propellers are shown in Table 1. The velocity at which the anchor reaches the soil surface is called the penetration velocity, v ₀ . The force acting on the anchor during the dynamic penetration of the anchor in the soil includes the effective weight W′ of the anchor in the water, the overlying soil pressure F _b on the anchor, the end bearing resistance F _bear , the frictional resistance F _frict , and the drag of the soil on the anchor Resistance F _D,s . The force of the anchor in the soil can be expressed by formula (3).

In the formula, z is the penetration depth of the anchor tip into the soil, and t is the time. For the new dynamic installation anchor, m=m _A , W′=W _A ′, the corresponding combination anchor m=m _A +m _B , W′=W _A ′+W _B ′, W _B ′ is the effective propeller in water weight. The following describes the values of each force.

(1) The end bearing resistance F _bear is the soil resistance experienced by the anchor in the direction perpendicular to the axis XX, as shown in formula (4).

F _bear ＝ N _c s _u A _t (4)

In the formula, N _c is the bearing capacity coefficient, which changes with the embedding depth. The calculation formula of N _c is shown in the formula (5a-5c), s _u is the undrained shear strength of the soil, and A _t is the anchor The contact area with the soil in the direction perpendicular to the axis XX.

In the formula, c ₁ and c ₂ are parameters related to the shape of the foundation, B is the width of the foundation, L is the length of the foundation, and z is the buried depth of the anchor plate. For the new anchor of the utility model, B is the thickness t _A of the triangular wing, and L is the width w _F of the triangular wing. For the propeller, both B and L are taken as the diameter D _B of the central shaft of the propeller.

(2) The friction resistance F _frict is the soil resistance on the side of the anchor, as shown in formula (6). In the formula, α is the friction coefficient between the anchor-soil interface, and A _s is the contact area between the anchor side and the soil.

F _frict = αs _u A _s (6)

(3) The overlying soil pressure F _b is the effective weight of the soil displaced by the anchor.

(4) The drag resistance F _D,s of the soil to the anchor can be calculated by formula (7).

In the formula, C _D,s is the drag resistance coefficient of the soil to the anchor, ρ _s is the saturation density of the soil, and v is the velocity of the anchor at any moment.

In addition, when the anchor penetrates the seabed at high speed, high shear strain rates occur in the soil around the anchor. Soils exhibit a rate effect at high shear strain rates, that is, soil strength increases as the shear strain rate increases. Therefore, the undrained shear strength considering the effect of soil volume ratio can be expressed as formula (8).

In the formula, R _f is the rate effect coefficient, s _u,ref is the reference shear strain rate The undrained shear strength of the soil obtained under is called the reference soil strength, and λ is the rate effect parameter, is the shear strain rate, which can be expressed by formula (9).

In the formula, d is the reference length. In the field test, the undrained shear strength of the soil is mainly measured by cone (Cone), T-shaped (T-bar) and spherical penetrometer (Ball penetrometer), which can be considered as the reference soil strength. At this time, the reference shear strain rate is taken as the ratio of the penetration velocity to the diameter of the penetrator. For the anchor, d is taken as the thickness of the wing plate; for the central shaft of the propeller, d is taken as the diameter of the central shaft of the propeller.

Assuming that the anchor-soil interface friction coefficient α = 0.33, the rate effect parameter λ = 0.14, the reference soil strength s _u,ref = 2.4+3zkPa, the parameters of the anchor and propeller are shown in Table 1, and the anchor can be determined according to formula (3). Or the relationship between velocity and depth when the combined anchor is driven into the soil. According to formula (2), the ultimate speed of the anchor and combined anchor can be calculated, which are 18.3 and 33.5m/s respectively. So for the anchor, two different penetration velocities are taken, which are 17 and 18m/s respectively. For combined anchors, five different speeds are taken, namely 17, 18, 20, 25 and 30 m/s. The relationship between the velocity of the anchor and combined anchors as a function of depth is shown in Figure 11.

It can be seen from Fig. 11(a) that when the penetration speed is 17m/s, the penetration depth of the anchor is 7.56m; after adding the propeller, the penetration depth of the anchor is 18.56m. Fig. 11(b) is the variation curve of the combined anchor velocity with depth at different penetration velocities. The speed of penetration of the anchor in the water is also increased by means of the thrusters, as already mentioned. When the penetration speed is 30m/s, the final penetration depth of the composite anchor is 24.88m. This shows that the propeller can increase the penetration depth of the anchor from two aspects: one is to increase the overall weight, thereby increasing the overall gravitational potential energy to increase the sinking depth of the anchor; the other is to increase the overall penetration in water speed, thereby increasing the overall kinetic energy, which can also increase the penetration depth of the anchor in the soil. The greater the depth of the anchor, the higher the corresponding bearing efficiency. Therefore, although installing the anchor of the present invention by means of a propeller increases the installation cost to a certain extent, the load-bearing efficiency of a single anchor is significantly improved. Therefore, the number of anchors required by the entire mooring system can be reduced, and the production, transportation and installation costs can be reduced, thereby reducing the total cost of the project.

Claims (1)

1. A novel lightweight power installation anchor is characterized in that the novel light power installation anchor mainly consists of wing plate (11), anchor handle (12) and connecting rod (14); described wing plate (11 ) is composed of two triangular flat plates symmetrically spliced, and the angle between the two is adjusted according to engineering requirements; two triangular flat plates of the wing plate (11) are symmetrically provided with a plurality of openings a (15); the connecting rod (14) Installed on the tail of the wing plate (11), the connecting rod (14) is provided with an opening b (17), and the connecting rod (14) is fixedly connected with the propeller (2) through the shear pin (3); The anchor handle (12) is an inverted V-shaped structure composed of two trapezoidal flat plates, the bottom of the anchor handle (12) is provided with a plurality of openings c (18), the opening c (18) and the opening a (15 ) cooperate with each other, and the anchor handle (12) is symmetrically fixed on the two triangular flat plates of the wing plate (11) through the bolt (16); the top of the anchor handle (12) is provided with an anchor eye (13), which is used to connect the working anchor chain (5) to provide pull-out bearing capacity; by adjusting the fixed position of the anchor handle (12), the anchor handle (12) moves up and down along the axial direction of the wing plate (11), thereby changing the offset of the anchor eye (13) , that is, the projection of the distance from the anchor eye (13) to the center of the soil resistance of the wing plate (11) in the axial direction of the wing plate (11), so that the new light-weight dynamic installation anchor has the performance of diving when it is subjected to an uplift load, The new lightweight dynamically installed anchors are embedded in the soil for bearing capacity.