A method for controlling the loss of soil during scour protection construction in offshore wind farms

Abstract

The present invention discloses a method for controlling the amount of loss in the construction of solidified soil scour protection for offshore wind farms, including: determining the strength of solidified soil corresponding to the maximum flow velocity of each high and low tide during the construction period of the offshore wind farm construction site; determining the critical flow velocity of initial setting and the critical flow velocity of final setting of solidified soil; estimating the construction workable time and reserving the final setting time of solidified soil; starting the solidification grouting construction when the measured flow velocity is lower than the critical flow velocity of initial setting, and stopping the solidification grouting at the end time of the construction operation according to the reserved final setting time of solidified soil; repeating the grouting multiple times, waiting for the rest time each time, so that the solidified soil protection structure fills the entire wind turbine foundation scour pit. The present invention does not need to monitor the evolution of the scour pit in real time, the method is simple, the cost is low, and it can effectively reduce the amount of loss and the construction quality of the solidified soil protection structure.

Description

Technical Field

[0001] The invention relates to a method for controlling the loss amount in the construction of solidified soil scour protection. Background Art

[0002] At present, many offshore wind farms that have been built are facing problems such as scouring, such as suspended submarine cables and exceeding the designed reserved depth. In severe cases, it may even affect the vibration frequency of the wind turbine foundation or lead to insufficient bearing capacity. Therefore, the repair of wind turbine foundation scour pits has begun. In the future, the repair of offshore pile foundation scour pits and foundation scour prevention will have a good market prospect. Scour protection traditionally uses stone throwing, sand blankets, silt solidification technology and other means. The structure and strength characteristics of solidified soil are conducive to improving soil strength and water stability, and effectively improving its anti-erosion ability. However, in harsh marine environments, the development and changes of underwater foundation scour pits and the loss of solidified soil are difficult to assess. It is often necessary to use multi-beam scanning and other monitoring technologies for scanning after the construction of the entire wind farm is completed. The quality of the protection project of a single foundation is difficult to guarantee, and re-grouting construction will greatly increase the construction cost. Summary of the invention

[0003] The purpose of the present invention is to provide a method for controlling the loss during the construction of solidified soil scour protection in an offshore wind farm. There is no need to monitor the evolution of scour pits in real time. The method is simple, low-cost, can effectively reduce the loss, and improve the construction quality of the solidified soil protection structure.

[0004] The technical solution to achieve the above purpose is:

[0005] The method of controlling the loss during the construction of scour protection of solidified soil in offshore wind farms includes:

[0006] Step S1, determining the strength of the solidified soil corresponding to the maximum flow velocity of each high and low tide during the construction period of the offshore wind farm construction site;

[0007] Step S2, determining the solidified soil ratio according to the solidified soil strength, and determining the solidified soil strength growth curve over time, and determining the initial setting critical flow rate and the final setting critical flow rate of the solidified soil according to the relationship between the solidified soil strength and the anti-scouring flow rate;

[0008] Step S3, calculating the solidified soil strength growth time of each stage of solidification construction according to the solidified soil strength growth curve over time, and estimating the construction workable time and reserving the solidified soil final setting time according to the local tidal current real-time change curve;

[0009] Step S4, the ship and the machine enter the point, and the solidification grouting construction starts when the measured flow rate is lower than the initial setting critical flow rate, and the solidification grouting is stopped at the end time of the construction operation according to the reserved final setting time of the solidified soil;

[0010] Step S5, repeating step S4 multiple times, waiting for a rest time each time, so that the solidified soil protection structure fills the entire wind turbine foundation scour pit.

[0011] Preferably, in step S1, the local hydrogeological conditions of the offshore wind farm construction site are investigated to determine the time of high and low tide and the flow rate variation pattern within the 7-day construction period, record the maximum flow rate of each high and low tide, and combine the relationship between the strength of the solidified soil and the anti-scouring flow rate to determine the strength of the solidified soil corresponding to each maximum flow rate.

[0012] Preferably, the construction period is selected during the low tide operation time when the flow velocity changes little.

[0013] Preferably, the final setting critical flow velocity can resist the maximum flow velocity occurring locally after construction.

[0014] Preferably, in step S5, after waiting for a rest period, when the measured flow rate is lower than the initial setting critical flow rate, the solidification grouting construction is restarted.

[0015] Preferably, the rest time is selected according to the strength increase time of the solidified soil.

[0016] The beneficial effects of the present invention are as follows: the present invention first determines the strength of the solidified soil, and then determines the proportion of the solidified soil, and improves the solidification strength in a short time to resist the possible increase in underwater flow rate before the solidified soil is completely solidified. The present invention does not need to monitor the loss of solidified soil in real time, has less construction technology and equipment, and has a simple method. It overcomes the problem of high loss rate of solidified soil during underwater pumping, effectively reduces construction costs, and improves the construction quality of solidified soil protective structures. The present invention can effectively reduce the loss of underwater grouting solidified soil, ensure project quality, avoid rework, and has almost no impact on the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of the method for controlling the amount of loss in the construction of scour protection of solidified soil in an offshore wind farm of the present invention;

[0018] Figure 2 It is a schematic diagram of the growth curve of the solidified soil strength over time in the present invention;

[0019] Figure 3 It is a schematic diagram of the relationship between the strength of the solidified soil and the anti-scour flow velocity in the present invention;

[0020] Figure 4 This is a schematic diagram of the construction operation time selection in the present invention;

[0021] Figure 5 is a curve showing the relationship between the grouting volume and time in the present invention;

[0022] Figure 6 It is a structural diagram of the solidified soil scour protection in the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings.

[0024] See also Figure 1-6 The method for controlling the loss during the scour protection construction of the offshore wind farm solidified soil of the present invention comprises the following steps:

[0025] Step S1, investigate the local hydrogeological conditions of the offshore wind farm construction site, determine the time of high and low tide and the change law of flow rate within 7 days of the construction period, and record the maximum flow rate V of each high and low tide i (i=1, 2, 3…), and combined with the relationship between the strength of the solidified soil and the anti-scouring flow velocity (such as Figure 3 ), determine the stabilized soil strength corresponding to each maximum flow velocity.

[0026] According to the ship operation window period, the low tide operation time with small flow velocity changes should be selected.

[0027] Step S2, determining the solidified soil ratio according to the solidified soil strength in step S1, determining and drawing a solidified soil strength growth curve over time, such as Figure 2 , according to the relationship between the strength of the stabilized soil and the anti-scouring flow velocity (such as Figure 3 ), determine the initial setting critical flow velocity v0 and final setting critical flow velocity v of the solidified soil f The final setting critical velocity v of the determined stabilized soil is f It should be able to resist the maximum flow velocity occurring locally after construction.

[0028] Step S3, according to the growth curve of solidified soil strength over time (such as Figure 2 ), calculate the solidified soil strength growth time of each stage of solidification construction, and estimate the construction workable time T according to the real-time change curve of local tidal current i (i=1, 2, 3…) and the final setting time T of the reserved solidified soil i (i=1, 2, 3...). like Figure 4 shown.

[0029] Step S4, the ship enters the point, and the solidification grouting construction begins when the measured flow rate is lower than the initial setting critical flow rate v0, and the reserved solidification soil final setting time T determined in step S3 is i , stop solidification grouting at the end of construction work to resist the loss caused by the failure of solidification of solidified soil when the tide rises or the flow rate increases.

[0030] Step S5, repeat step S4 multiple times, that is: after waiting for the pause time t, the measured flow rate is lower than the critical flow rate v0 for initial setting, and then restart the solidification grouting construction. The solidified soil protection structure fills the entire fan foundation scour pit. Among them, the selection of the pause time should take into account the solidified soil strength growth time to ensure that the solidified soil completes initial setting before the flow rate increases after construction. Figure 5 shown.

[0031] In summary, the present invention overcomes the problem of high loss rate of solidified soil during underwater pumping, effectively reduces construction costs, improves the construction quality of the solidified soil protection structure, and ensures that the solidified soil protection structure forms a complete hard shell layer.

[0032] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the relevant technical field may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by the claims.

Claims

1. A method for controlling the loss of soil during scour protection construction in an offshore wind farm, characterized in that: include: Step S1, determining the strength of the solidified soil corresponding to the maximum flow velocity of each high and low tide during the construction period of the offshore wind farm construction site; Step S2, determining the solidified soil ratio according to the solidified soil strength, and determining the solidified soil strength growth curve over time, and determining the initial setting critical flow rate and the final setting critical flow rate of the solidified soil according to the relationship between the solidified soil strength and the anti-scouring flow rate; Step S3, calculating the solidified soil strength growth time of each stage of solidification construction according to the solidified soil strength growth curve over time, and estimating the construction workable time and reserving the solidified soil final setting time according to the local tidal current real-time change curve; Step S4, the ship and the machine enter the point, and the solidification grouting construction starts when the measured flow rate is lower than the initial setting critical flow rate, and the solidification grouting is stopped at the end time of the construction operation according to the reserved final setting time of the solidified soil; Step S5, repeating step S4 multiple times, waiting for a rest time each time, so that the solidified soil protection structure fills the entire wind turbine foundation scour pit; In step S1, the local hydrogeological conditions of the offshore wind farm construction site are investigated to determine the time of high and low tide and the change law of flow velocity within 7 days of the construction period, record the maximum flow velocity of each high and low tide, and determine the strength of the solidified soil corresponding to each maximum flow velocity in combination with the relationship between the strength of the solidified soil and the anti-scouring flow velocity; In step S5, after waiting for a rest period, when the measured flow rate is lower than the initial setting critical flow rate, the solidification grouting construction is restarted.

2. The method for controlling the loss during the scour protection construction of the offshore wind farm solidified soil according to claim 1 is characterized in that: During the construction period, choose the low tide time when the flow velocity changes little.

3. The method for controlling the loss during the scour protection construction of the offshore wind farm solidified soil according to claim 1 is characterized in that: The final setting critical flow velocity can resist the maximum flow velocity that occurs locally after construction.

4. The method for controlling the loss during the scour protection construction of offshore wind farm solidified soil according to claim 1 is characterized in that: Select the rest time according to the strength increase time of the solidified soil.

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