Auxiliary installation device and installation method for single-column composite cylinder foundation

Abstract

The application relates to the offshore wind power technology field, in particular to an auxiliary installation device of a single-column composite cylinder type foundation. The auxiliary installation device of the single-column composite cylinder type foundation comprises a floating block, a connecting frame, an extension assembly, a control system and an arc-shaped coaming, multiple floating blocks are distributed in a ring shape at equal intervals, an opening for the single-column composite cylinder type foundation to enter and exit is reserved between a pair of adjacent floating blocks, the remaining two adjacent floating blocks are connected through the connecting frame, an extension assembly connected with the control system is connected to the outer wall of each floating block, the free end of the extension assembly is connected with the arc-shaped coaming, and multiple arc-shaped coamings enclose a ring-shaped space for accommodating the single-column composite cylinder type foundation. The auxiliary installation device of the single-column composite cylinder type foundation can realize stable floating transportation of the single-column composite cylinder type foundation.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power technology, and in particular to an auxiliary installation device for a single-column composite cylindrical foundation, and an installation method for a single-column composite cylindrical foundation using the auxiliary installation device. Background Technology

[0002] As one of the foundation types suitable for offshore wind turbines with shallow overburden geology, cylindrical foundations have advantages such as rapid construction, environmental friendliness, and easy recycling. In my country's offshore wind farm projects, the use of single-column composite cylindrical foundations is the most common.

[0003] Currently, the transportation and installation of single-column composite cylindrical foundations mainly adopts the following two methods: 1. Dry transportation using large flatbed barges, dedicated transport vessels, or semi-submersible barges, followed by lifting and installation using large crane barges to form the single-column composite cylindrical foundation, tower, and wind turbine into an offshore wind turbine body and complete its sinking. 2. Directly installing the single-column composite cylindrical foundation, tower, and wind turbine into an offshore wind turbine body, and then utilizing the inflatable self-buoyancy of the single-column composite cylindrical foundation for floating transportation and sinking of the offshore wind turbine body.

[0004] The first method, due to the use of large ship machinery, results in higher transportation and installation costs for the single-column composite cylindrical foundation. Although the second method can save on transportation and installation costs, the single-column composite cylindrical foundation has limited self-floating performance under complex sea conditions, making it prone to tilting and difficult to meet the stability requirements for floating. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides an auxiliary installation device for a single-column composite cylindrical foundation that enables stable floating of the single-column composite cylindrical foundation.

[0006] The present invention adopts the following technical solution:

[0007] This invention provides an auxiliary installation device for a single-column composite cylindrical foundation, comprising floats, connecting frames, telescopic components, a control system, and arc-shaped enclosures. Multiple floats are evenly spaced and circumferentially distributed, with an opening reserved between adjacent pairs of floats for the single-column composite cylindrical foundation to enter and exit. The remaining two adjacent floats are connected by the connecting frames. Each float has a telescopic component connected to the control system signal on its outer wall. The free end of the telescopic component is connected to the arc-shaped enclosures. Multiple arc-shaped enclosures form an annular space to accommodate the single-column composite cylindrical foundation.

[0008] Preferably, the floats are hollow cylindrical structures, and the axes of multiple floats are parallel to the axis of the annular space.

[0009] Preferably, the connecting frame includes connecting rods and reinforcing rods. The two ends of the two connecting rods are respectively connected to a float. Multiple reinforcing rods are provided in the space between the two connecting rods, and the two ends of each reinforcing rod are respectively connected to a connecting rod.

[0010] Preferably, the telescopic assembly includes a support frame and a hydraulic jacking component connected to the control system signal. One end of the support frame is fixed to the outer wall of the float, and the other end of the support frame is connected to the hydraulic jacking component. The telescopic end of the hydraulic jacking component is connected to the arc-shaped enclosure.

[0011] Preferably, the arc-shaped enclosure includes an arc-shaped outer plate and an elastic pad, the outer arc surface of the arc-shaped outer plate is connected to the free end of the telescopic component, and the inner arc surface of the arc-shaped outer plate is covered with an elastic pad.

[0012] This invention also provides an installation method for a single-column composite cylindrical foundation, employing the aforementioned auxiliary installation device for the single-column composite cylindrical foundation, and including the following steps:

[0013] S1: Install the tower and wind turbine in sequence on the top of the single-column composite cylindrical foundation;

[0014] S2: Move the single-column composite cylindrical foundation into and confine it within the annular space of the auxiliary installation device for the single-column composite cylindrical foundation;

[0015] S3: Lower the lower part of the single-column composite cylindrical foundation and the auxiliary installation device of the single-column composite cylindrical foundation into the water as a whole, and move it to the machine location position;

[0016] S4: Lower the single-column composite cylindrical foundation separately to contact the seabed surface, so that the auxiliary installation device of the single-column composite cylindrical foundation is detached from the single-column composite cylindrical foundation, and complete the recovery of the auxiliary installation device of the single-column composite cylindrical foundation.

[0017] Preferably, step S2 includes:

[0018] S21: The control system on the auxiliary installation device of the single-column composite cylindrical foundation controls the retraction of multiple telescopic components, moving the single-column composite cylindrical foundation from the opening between an adjacent pair of floating blocks into the annular space.

[0019] S22: Multiple telescopic components are extended by the control system, and multiple arc-shaped enclosures surround and limit the single-column composite cylindrical foundation.

[0020] Preferably, step S3 includes:

[0021] S31: Launch the single-column composite cylindrical foundation together with the auxiliary installation device of the single-column composite cylindrical foundation into the harbor basin as a whole, and control the waterline to be located on the cylindrical section of the single-column composite cylindrical foundation.

[0022] S32: the draft of the cylinder section of the single-column composite cylinder foundation is kept unchanged, and the single-column composite cylinder foundation is integrally moved into the deep water area together with the auxiliary installation device of the single-column composite cylinder foundation;

[0023] S33: the gravity center of the single-column composite cylinder foundation is lowered, the waterline is located on the single-column section of the single-column composite cylinder foundation, and the single-column composite cylinder foundation is controlled to move to the position of the shooting site together with the auxiliary installation device of the single-column composite cylinder foundation.

[0024] Preferably, step S4 comprises:

[0025] S41: the single-column composite cylinder foundation is gradually lowered to contact the seabed surface through continuous pumping of the pump group at the top of the internal cabin of the single-column composite cylinder foundation;

[0026] S42: the multiple telescopic assemblies are controlled to retract through the control system on the auxiliary installation device of the single-column composite cylinder foundation, and the auxiliary installation device of the single-column composite cylinder foundation is pulled out of the single-column composite cylinder foundation through the opening reserved between the adjacent pair of floating blocks by the cable on the ship;

[0027] S43: the auxiliary installation device of the single-column composite cylinder foundation is pulled back into the harbor basin by the tugboat.

[0028] Preferably, after the single-column composite cylinder foundation is moved into the annular space of the auxiliary installation device of the single-column composite cylinder foundation, the spacing distance between the floating blocks on the auxiliary installation device of the single-column composite cylinder foundation and the single-column composite cylinder foundation is more than two meters.

[0029] Compared with the prior art, the single-column composite cylinder foundation of the present application has the following advantages:

[0030] When the auxiliary installation device of the single-column composite cylinder foundation of the present application is used, the single-column composite cylinder foundation is arranged in the annular space, and the extension of the multiple telescopic assemblies is controlled by the control system, so that the single-column composite cylinder foundation is radially limited and the inclination posture is corrected by the multiple arc-shaped coamings, thereby the axial movement of the single-column composite cylinder foundation is not affected. Then, the auxiliary installation device of the single-column composite cylinder foundation and the single-column composite cylinder foundation are integrally launched and transported. During the whole process, the buoyancy provided by the floating blocks on the auxiliary installation device of the single-column composite cylinder foundation and the buoyancy of the single-column composite cylinder foundation itself are used to avoid excessive dependence on and use of large transport ships and large floating crane ships, which is beneficial to saving engineering costs.

[0031] The installation method of the single-column composite cylinder type foundation of the present application adopts the auxiliary installation device of the single-column composite cylinder type foundation described above, and naturally has the related effects of the auxiliary installation device of the single-column composite cylinder type foundation described above. Meanwhile, in the installation method of the single-column composite cylinder type foundation of the present application, the tower cylinder and the wind turbine are installed on the single-column composite cylinder type foundation in advance before being transported by water, so that the over-reliance on and use of large wind turbine installation ships and other ship-machine equipment resources are also avoided, and the engineering construction cost is greatly saved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a three-dimensional structure schematic diagram of the auxiliary installation device of the first form of single-column composite cylinder type foundation in the embodiment of the present application.

[0033] Figure 2 is Figure 1 is a top view structure schematic diagram of the auxiliary installation device of the first form of single-column composite cylinder type foundation.

[0034] Figure 3 is a three-dimensional structure schematic diagram of the auxiliary installation device of the second form of single-column composite cylinder type foundation in the embodiment of the present application.

[0035] Figure 4 is a structure schematic diagram of the auxiliary installation device of the first form of single-column composite cylinder type foundation in the embodiment of the present application when assisting in transporting the single-column composite cylinder type foundation on the sea surface.

[0036] In the drawings, the reference signs are explained as follows:

[0037] 1, floating block 4, arc-shaped coaming

[0038] 2, connecting frame 41, arc-shaped outer plate

[0039] 21, connecting rod 5, single-column composite cylinder type foundation

[0040] 22, reinforcing rod 6, opening

[0041] 3, telescopic assembly 7, annular space

[0042] 31, support frame 8, tug

[0043] 32, hydraulic thrust piece DETAILED DESCRIPTION

[0044] The specific embodiments of the present application will be further described in detail below in combination with the drawings. These embodiments are only used to illustrate the present application, and are not a limitation on the present application.

[0045] 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 shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] 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 fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through 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.

[0047] In addition, in the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0048] Referring to Figures 1 to 3 , the embodiment provides an auxiliary installation device for single-column composite cylinder type foundation, comprising a plurality of floating blocks 1, connecting frames 2, telescopic assemblies 3, a control system and arc-shaped coaming 4, the plurality of floating blocks 1 are distributed equidistantly and circumferentially, and an opening 6 for the single-column composite cylinder type foundation 5 to enter and exit is reserved between each pair of adjacent floating blocks 1, and the remaining two adjacent floating blocks 1 are connected by the connecting frames 2, and one telescopic assembly 3 connected with the control system signal is connected to the outer wall of each floating block 1, and the free end of the telescopic assembly 3 is connected with the arc-shaped coaming 4, and the plurality of arc-shaped coaming 4 enclose a ring-shaped space 7 for accommodating the single-column composite cylinder type foundation 5.

[0049] The auxiliary installation device for single-column composite cylinder type foundation of the embodiment is used by setting the single-column composite cylinder type foundation 5 in the ring-shaped space 7, and controlling the elongation of the plurality of telescopic assemblies 3 by the control system, and realizing the embracing and limiting of the single-column composite cylinder type foundation 5 by the plurality of arc-shaped coaming 4, so as to complete the stability radial limiting and deflection correction of the single-column composite cylinder type foundation 5, and the axial movement of the single-column composite cylinder type foundation 5 is not affected, then the auxiliary installation device for single-column composite cylinder type foundation and the single-column composite cylinder type foundation 5 are launched and transported as a whole, and in the whole process, the buoyancy provided by the floating blocks 1 of the auxiliary installation device for single-column composite cylinder type foundation and the buoyancy of the single-column composite cylinder type foundation 5 itself are used to avoid excessive dependence and use of large transport ships and large floating crane ships, which is beneficial to saving engineering cost.

[0050] It should be noted that the number of floating blocks 1 and connecting frames 2 can be appropriately adjusted on the premise that the stability meets the requirements, according to the principle that the inertia moments of the waterline areas of the floating blocks 1 are equal.

[0051] Preferably, in the embodiment, the number of floating blocks 1 is n, and the number of connecting frames 2 is n-1, wherein n is 3-6. Referring to Figure 1 In this specific embodiment, n is 3; referring to Figure 3 In this specific embodiment, n is 6.

[0052] Preferably, the floating blocks 1 are hollow cylindrical structures, and the axes of the plurality of floating blocks 1 are parallel to the axis of the annular space 7, so as to ensure that the auxiliary installation device of the single-column composite cylindrical foundation stably limits the single-column composite cylindrical foundation 5 in the radial direction and deflection.

[0053] It should be noted that the diameter and height of the floating blocks 1 should be determined according to the stability calculation results, which are not limited here, as long as the overall stability of the single-column composite cylindrical foundation 5 meets the specification requirements after being sleeved into the annular space 7 of the auxiliary installation device of the single-column composite cylindrical foundation.

[0054] Preferably, referring to Figure 1 and Figure 3 The connecting frame 2 comprises connecting rods 21 and reinforcing rods 22, both ends of the two connecting rods 21 are connected with a floating block 1 respectively, and a plurality of reinforcing rods 22 are arranged in the space between the two connecting rods 21, both ends of each reinforcing rod 22 are connected with a connecting rod 21 respectively. The arrangement of the reinforcing rods 22 can provide strength support for the connecting frame 2 to prevent the connecting frame 2 from being damaged under stress.

[0055] Preferably, referring to Figure 1 and Figure 3 The telescopic assembly 3 comprises a support frame 31 and a hydraulic thrust piece 32 connected with the control system signal, one end of the support frame 31 is fixed on the outer wall of the floating block 1, the other end of the support frame 31 is connected with the hydraulic thrust piece 32, and the telescopic end of the hydraulic thrust piece 32 is connected with the arc-shaped coaming 4.

[0056] Preferably, referring to Figure 1 The arc-shaped coaming 4 comprises an arc-shaped outer plate 41 and an elastic protective pad, the outer arc surface of the arc-shaped outer plate 41 is connected with the free end of the telescopic assembly 3, and the inner arc surface of the arc-shaped outer plate 41 is covered with the elastic protective pad. The arrangement of the elastic protective pad on the inner arc surface of the arc-shaped outer plate 41 provides a certain buffer for the arc-shaped outer plate 41 when the arc-shaped coaming 4 embraces the single-column composite cylindrical foundation 5, so as to prevent the arc-shaped outer plate 41 from being damaged by abrasion.

[0057] The embodiment also provides a method for installing the single-column composite cylinder type foundation, which adopts the auxiliary installation device for the single-column composite cylinder type foundation and comprises the following steps.

[0058] S1: sequentially installing the tower cylinder and the wind turbine on the upper part of the single-column composite cylinder type foundation 5;

[0059] S2: moving the single-column composite cylinder type foundation 5 into and limiting in the annular space 7 of the auxiliary installation device for the single-column composite cylinder type foundation;

[0060] S3: integrally launching the single-column composite cylinder type foundation 5 and the auxiliary installation device for the single-column composite cylinder type foundation downward and moving to the shooting point position;

[0061] S4: separately launching the single-column composite cylinder type foundation 5 to contact the seabed surface, making the auxiliary installation device for the single-column composite cylinder type foundation separate from the single-column composite cylinder type foundation 5, and completing the recovery of the auxiliary installation device for the single-column composite cylinder type foundation.

[0062] The method for installing the single-column composite cylinder type foundation of the embodiment adopts the auxiliary installation device for the single-column composite cylinder type foundation, and naturally has the related effects of the auxiliary installation device for the single-column composite cylinder type foundation. Meanwhile, in the method for installing the single-column composite cylinder type foundation, the tower cylinder and the wind turbine are installed on the single-column composite cylinder type foundation 5 in advance before launching and transportation, so that the over-reliance on and use of large wind turbine installation ships and other ship-machine equipment resources are avoided, and the engineering construction cost is greatly saved.

[0063] Preferably, the step S2 comprises:

[0064] S21: controlling the plurality of telescopic assemblies 3 to retract by the control system on the auxiliary installation device for the single-column composite cylinder type foundation, and moving the single-column composite cylinder type foundation 5 into the annular space 7 from the opening 6 between the adjacent pair of floating blocks 1;

[0065] S22: controlling the plurality of telescopic assemblies 3 to extend by the control system, and limiting the single-column composite cylinder type foundation 5 by the plurality of arc-shaped coaming plates 4.

[0066] Preferably, the step S3 comprises:

[0067] S31: integrally launching the single-column composite cylinder type foundation 5 and the auxiliary installation device for the single-column composite cylinder type foundation into the harbor basin, and controlling the waterline to be located on the cylinder section of the single-column composite cylinder type foundation 5;

[0068] S32: keeping the water depth of the cylinder section of the single-column composite cylinder type foundation 5 unchanged, and integrally moving the single-column composite cylinder type foundation 5 and the auxiliary installation device for the single-column composite cylinder type foundation into the deep water area;

[0069] S33: The center of gravity of the single-column composite cylinder foundation 5 is lowered, the waterline is located on the single-column section of the single-column composite cylinder foundation 5, and the single-column composite cylinder foundation 5 is controlled to move to the site location together with the auxiliary installation device of the single-column composite cylinder foundation.

[0070] It should be noted that step S31 can be launched into the harbor basin by using the launching method commonly used in the prior art or the launching method in the dock; the adjustment of the draft (the substantial adjustment of the center of gravity) of the single-column composite cylinder foundation 5 is achieved by controlling the pump group at the top of the internal cabin of the single-column composite cylinder foundation 5 to exhaust air, and adjusting the water-gas volume ratio in the cabin; the overall movement of the single-column composite cylinder foundation 5 together with the auxiliary installation device of the single-column composite cylinder foundation is achieved by the traction of the tugboat 8.

[0071] Preferably, step S4 comprises:

[0072] S41: The single-column composite cylinder foundation 5 is gradually lowered to contact the seabed surface by the continuous air exhaust of the pump group at the top of the internal cabin of the single-column composite cylinder foundation 5;

[0073] S42: The multiple telescopic assemblies 3 are controlled to retract by the control system on the auxiliary installation device of the single-column composite cylinder foundation, and the auxiliary installation device of the single-column composite cylinder foundation is pulled out of the single-column composite cylinder foundation 5 through the opening 6 reserved between the adjacent pair of floating blocks 1 by the cable on the ship;

[0074] S43: The auxiliary installation device of the single-column composite cylinder foundation is pulled back into the harbor basin by the tugboat 8.

[0075] Preferably, after the single-column composite cylinder foundation 5 is moved into the annular space 7 of the auxiliary installation device of the single-column composite cylinder foundation, the spacing distance between the floating block 1 on the auxiliary installation device of the single-column composite cylinder foundation and the single-column composite cylinder foundation 5 is more than two meters. Since the single-column composite cylinder foundation 5 is more prone to deflection during the floating process after the tower cylinder and the wind turbine generator are sequentially installed on the upper part of the single-column composite cylinder foundation 5, the spacing distance of more than two meters between the floating block 1 and the single-column composite cylinder foundation 5 can ensure that the auxiliary installation device of the single-column composite cylinder foundation does not deflect with the single-column composite cylinder foundation 5, thereby better achieving the radial limiting of the stability and the deflection posture correction of the single-column composite cylinder foundation 5.

[0076] Further, referring to Figure 4 , in order to better adjust the single-column composite cylinder foundation 5, two tugboats 8 can be equipped and pull the auxiliary installation device of the single-column composite cylinder foundation in opposite directions, so as to adjust the position of the single-column composite cylinder foundation 5 by adjusting the angle of the auxiliary installation device of the single-column composite cylinder foundation relative to the horizontal plane.

[0077] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and replacements can be made 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 method of installing a single column composite caisson type foundation, characterized by, The auxiliary installation device is used for assisting transportation of the single-column composite cylinder type foundation in an erected state, and comprises floating blocks (1), connecting frames (2), telescopic assemblies (3), a control system and arc-shaped coaming plates (4). A plurality of the floating blocks (1) are distributed in a ring shape at equal intervals, and an opening for the single-column composite cylinder type foundation (5) to enter and exit is reserved between a pair of adjacent floating blocks (1). The remaining two adjacent floating blocks (1) are connected through the connecting frames (2). An outer wall of each floating block (1) is connected with one telescopic assembly (3) connected with the control system. The free end of the telescopic assembly (3) is connected with the arc-shaped coaming plate (4). A plurality of the arc-shaped coaming plates (4) surround a ring-shaped space (7) for accommodating the single-column composite cylinder type foundation (5). The method comprises the following steps: S1: installing a tower cylinder and a wind turbine in sequence on the upper part of the single-column composite cylinder type foundation (5); S2: first, the single-column composite cylinder type foundation (5) is moved into the ring-shaped space (7) from the opening (6) between a pair of adjacent floating blocks (1) by retracting the telescopic assemblies (3) controlled by the control system; then, the single-column composite cylinder type foundation (5) is ring-enclosed and limited by the arc-shaped coaming plates (4) by extending the telescopic assemblies (3) controlled by the control system; S3: first, the single-column composite cylinder type foundation (5) and the auxiliary installation device are integrally launched into a harbor basin, and the waterline is located on the cylinder section of the single-column composite cylinder type foundation (5); then, the water depth of the cylinder section of the single-column composite cylinder type foundation (5) is kept unchanged, and the single-column composite cylinder type foundation (5) and the auxiliary installation device are integrally moved into a deep water area; then, the center of gravity of the single-column composite cylinder type foundation (5) is lowered, the waterline is located on the single-column section of the single-column composite cylinder type foundation (5), and the single-column composite cylinder type foundation (5) and the auxiliary installation device are moved to a position of a machine together; S4: first, the single-column composite cylinder type foundation (5) is gradually lowered to contact the seabed surface by continuous air extraction of a pump group on the top of an internal cabin of the single-column composite cylinder type foundation (5); then, the telescopic assemblies (3) are retracted by the control system on the auxiliary installation device, and the auxiliary installation device is separated from the single-column composite cylinder type foundation (5) by a cable on a ship through the opening (6) between a pair of adjacent floating blocks (1); then, the auxiliary installation device is pulled back to the harbor basin by a tugboat (8).

2. The method of installing a single column composite cylinder type foundation according to claim 1, characterized by, The floating blocks (1) are hollow cylinder structures, and the axes of the floating blocks (1) are parallel to the axis of the ring-shaped space (7).

3. The method of installing a single column composite cylinder type foundation according to claim 1, characterized by, The connecting frame (2) comprises connecting rods (21) and reinforcing rods (22). The two ends of the two connecting rods (21) are connected with one floating block (1) respectively. A plurality of the reinforcing rods (22) are arranged in the space between the two connecting rods (21). The two ends of each reinforcing rod (22) are connected with one connecting rod (21) respectively.

4. The method of installing a single column composite cylinder type foundation according to claim 1, characterized by, The telescopic assembly (3) comprises a support frame (31) and a hydraulic pushing piece (32) connected with the control system, one end of the support frame (31) is fixed on the outer wall of the floating block (1), the other end of the support frame (31) is connected with the hydraulic pushing piece (32), and the telescopic end of the hydraulic pushing piece (32) is connected with the arc-shaped coaming (4).

5. The method of installing a single column composite cylinder type foundation according to claim 1, wherein The arc-shaped coaming (4) comprises an arc-shaped outer plate (41) and an elastic protective pad, the outer arc surface of the arc-shaped outer plate (41) is connected with the free end of the telescopic assembly (3), and the inner arc surface of the arc-shaped outer plate (41) is covered with the elastic protective pad.

6. The method of installing a single column composite cylinder type foundation according to claim 1, wherein After the single-column composite cylinder type foundation (5) is moved into the annular space (7) of the auxiliary installation device, the spacing distance between the floating block (1) on the auxiliary installation device and the single-column composite cylinder type foundation (5) is more than two meters.

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