Construction method of offshore sludge solidified soil-riprap mixed anti-scouring structure

Abstract

The invention relates to a construction method of an offshore sludge solidified soil-riprap mixed anti-scouring structure, the anti-scouring protection structure sequentially comprises a riprap layer, a high-fluidity strong-compactness flow state solidified soil layer and a low-fluidity high-strength flow state solidified soil layer from bottom to top, and the anti-scouring protection structure is formed by sequentially filling during construction; the riprap layer is poured into the scouring pit by a certain depth, the high-flowability and high-density flow state solidified soil is formed through self-leveling pouring based on the riprap layer, and the low-flowability and high-strength flow state solidified soil layer is formed through self-leveling pouring based on the high-flowability and high-density flow state solidified soil. According to the invention, the riprap layer is combined with the high-flowability strong-compactness flow-state solidified soil and the low-flowability high-strength flow-state solidified soil which are different in strength and anti-scouring performance, so that the problem of poor protection effect of the riprap protection layer caused by riprap pore scouring is avoided; and the high construction cost caused by full-pouring anti-scouring flow state solidified soil is also reduced.

Description

Technical Field

[0001] The present invention relates to the fields of marine engineering and renewable energy, and in particular to a construction method of an offshore silt-solidified soil-riprap mixed anti-scour structure. Background Art

[0002] As a clean, efficient, and renewable energy source, offshore wind power plays an increasingly important role in the global energy transition. With the gradual decline of fossil energy resources and the continuous improvement of environmental protection requirements, the development and utilization of offshore wind power has become a key technical means to achieve carbon neutrality.

[0003] A Chinese patent application document with publication number CN115392152A is disclosed in the prior art. The document discloses a construction method for repairing scour of a cross-sea bridge pile group foundation using solidified soil. The method involves subjecting the mud to a fluidizing solidification treatment to produce a high-water-content fluidized solidified soil. The high-water-content fluidized solidified soil is then pumped into the scour pits around the cross-sea bridge pile group foundations using its early fluidity. The soil gradually solidifies to form a filling structure to repair the scour pits, resulting in high construction costs.

[0004] Over the long term, offshore wind turbine pile foundations are subject to dynamic hydraulic forces such as tidal currents, waves, and ocean currents, potentially causing scouring of the surrounding seabed soil, thereby impacting the stability and service life of the pile foundations. Traditional scouring mitigation methods include direct riprap and precast concrete cushions, but these methods are complex to construct, have limited applicability, and pose significant environmental risks. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method for an offshore silt-solidified soil-riprap mixed anti-scour structure to cope with the scouring around the wind turbine foundation under complex sea conditions, avoid the poor protective effect of the riprap protective layer caused by the scouring of the riprap pores, and reduce the high construction cost caused by the full casting of anti-scouring fluidized solidified soil.

[0006] The object of the present invention is achieved by providing a method for constructing a marine silt-solidified soil-riprap mixed anti-scour structure, wherein the anti-scour protection structure is filled in a scour pit where a pile foundation is located, and comprises, from bottom to top, a riprap layer, a high-fluidity, highly dense, fluidized solidified soil layer, and a relatively low-fluidity, high-strength fluidized solidified soil layer. During construction, the riprap layer, the high-fluidity, highly dense, fluidized solidified soil layer, and the relatively low-fluidity, high-strength fluidized solidified soil layer are filled in sequence, and the riprap layer, the high-fluidity, highly dense, fluidized solidified soil layer, and the relatively low-fluidity, high-strength fluidized solidified soil layer wrap around the pile foundation.

[0007] Among them, the riprap layer is cast at a certain depth in the scouring pit, the high-fluidity and highly dense fluidized solidified soil is self-leveled and cast based on the riprap layer, and the low-fluidity and high-strength fluidized solidified soil layer is self-leveled and cast based on the high-fluidity and highly dense fluidized solidified soil.

[0008] Furthermore, the filling depth of the riprap layer is H s -5d 50 , where H s is the depth of the pit, d 50 is the median particle size of the riprap layer.

[0009] Furthermore, the filling thickness of the high-fluidity, dense, fluidized solidified soil layer is 2d 50 .

[0010] Furthermore, the filling thickness of the low fluidity high strength fluidized solidified soil layer is 3d 50 .

[0011] Furthermore, the scour pit where the pile foundation is located is in the shape of an inverted truncated cone, and the riprap layer formed is in the shape of an inverted truncated cone. The diameter of the horizontal cross-section circle of the riprap layer is 1-2 times the diameter of the pile foundation.

[0012] Furthermore, the diameter of the formed high-fluidity, highly dense, fluidized solidified soil layer is 1-2 times the diameter of the pile foundation.

[0013] Furthermore, the median particle size of the riprap in the riprap layer is between 240 mm and 480 mm.

[0014] Furthermore, the high-fluidity, highly dense, fluidized solidified soil layer is formed by combining the following parts: soil, 20 parts; new curing agent, 3 parts; water, 21 parts.

[0015] Furthermore, the low-fluidity high-strength fluidized solidified soil layer is formed by combining the following parts: soil, 20 parts; the new solidifying agent, 5 parts; and water, 19 parts.

[0016] Furthermore, the diameter of the low-fluidity and high-strength fluidized solidified soil layer is 2-3 times the diameter of the pile foundation.

[0017] The beneficial effects of the present invention are:

[0018] 1. A three-layer structure is constructed by combining a riprap layer, a high-flowability, highly dense fluidized soil layer, and a low-flowability, high-strength fluidized soil layer from bottom to top. This avoids the poor protection effect of traditional riprap protection due to pore washing, and also reduces the high construction costs caused by fully poured fluidized soil.

[0019] 2. The riprap layer and high-fluidity and high-density fluidized solidified soil mainly play the role of filling the scour pit and ensuring the stability of the pile foundation, while the low-fluidity and high-strength fluidized solidified soil mainly plays the role of anti-scour. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the solution of the present invention.

[0021] Explanation of reference numerals: 1-pile foundation; 2-riprap layer; 3-high fluidity and strong dense fluidized solidified soil layer; 4-low fluidity and high strength fluidized solidified soil layer. DETAILED DESCRIPTION

[0022] The following is a combination of the embodiments of the present invention Figure 1 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] like Figure 1 As shown in the figure, a construction method of an offshore silt solidified soil-riprap mixed anti-scour structure is proposed, which requires the establishment of a fluidized solidified soil-riprap structure for the offshore wind turbine foundation. The fluidized solidified soil-riprap structure is a layered protection structure distributed around the bottom of the pile foundation 1. The anti-scour protection structure is filled in the inverted cone-shaped scour pit where the pile foundation 1 is located (the pile foundation 1 is coaxially fixed and inserted into the scour pit to a certain depth, and the position of the pile foundation 1 itself is fixed). From bottom to top, it is the riprap layer 2, the highly fluid and dense fluidized solidified soil layer 3 and the low fluidity high strength fluidized solidified soil layer 4, the riprap layer 2, the high fluidity strong dense fluidized solidified soil layer 3 and the low fluidity high strength fluidized solidified soil layer 4 are combined into a stable integral structure; during construction, the riprap layer 2, the high fluidity strong dense fluidized solidified soil layer 3 and the low fluidity high strength fluidized solidified soil layer 4 are filled in sequence, the riprap layer 2, the high fluidity strong dense fluidized solidified soil layer 3 and the low fluidity high strength fluidized solidified soil layer 4 wrap the pile foundation 1 and fit tightly with the inner wall of the scouring pit.

[0024] Among them, the riprap layer 2 is first cast to a certain depth in the scouring pit; then the scouring pit is filled with high-fluidity and highly dense fluidized solidified soil 3, and the high-fluidity and highly dense fluidized solidified soil 3 is self-leveled and cast based on the riprap layer 2, completely covering the riprap layer 2, and fully infiltrating and filling the gaps in the riprap layer 2 under the action of gravity; the lower-fluidity and high-strength fluidized solidified soil layer 4 is self-leveled and cast based on the high-fluidity and highly dense fluidized solidified soil 3, and the lower-fluidity and high-strength fluidized solidified soil layer 4 completely covers the high-fluidity and highly dense fluidized solidified soil 3, and the laying size of the lower-fluidity and high-strength fluidized solidified soil 4 is slightly higher than the seabed surface with the pile foundation 1 as the base point.

[0025] It is worth noting that the technical requirements for high-fluidity, highly dense fluidized solidified soil 3 and low-fluidity, high-strength fluidized solidified soil 4 are as follows:

[0026] Highly fluid and dense fluidized solidified soil 3 can fill the pores of the riprap layer under the action of gravity. At the same time, the mechanical properties and durability of the solidified soil meet the requirements of hydraulic engineering design.

[0027] The retention rate of the low-fluidity and high-strength fluidized solidified soil 4 can meet more than 80% under the condition of a water flow velocity of 2.5 m / s. The strength in the later stage of solidification can withstand long-term wave flow loads, and the practical effect is good.

[0028] The above-mentioned high-fluidity and high-density fluidized solidified soil 3 and the relatively low-fluidity and high-strength fluidized solidified soil 4 are both prefabricated on a construction vessel and poured into the scouring pit by special equipment.

[0029] The method is equipped with a construction vessel and an underwater monitoring system is set up on the construction vessel. The underwater monitoring system includes underwater monitoring equipment. During the process of filling the riprap layer 2, the high-fluidity and highly dense fluidized solidified soil layer 3 and the relatively low-fluidity and high-strength fluidized solidified soil layer 4, the underwater monitoring equipment is used to monitor and record images of the construction site. The staff on the construction vessel can check the underwater filling process at any time to adjust the construction process in time.

[0030] The filling depth of the riprap layer 2 is H s -5d 50 , where H s is the depth of the pit, d 50 is the median particle size of the riprap layer 2, and the filling thickness of the high-fluidity, dense, fluidized solidified soil layer 3 is 2d 50 High fluidity and high density fluidized solidified soil layer 3 is composed of the following parts: soil, 20 parts; new curing agent, 3 parts; water, 21 parts; low fluidity and high strength fluidized solidified soil layer 4 filling thickness of 3d 50 The low-fluidity and high-strength fluidized solidified soil layer 4 is composed of the following parts: soil, 20 parts; new solidifying agent, 5 parts; water, 19 parts.

[0031] The soil and the new curing agent of the high-fluidity, high-density fluidized solidified soil layer 3 and the relatively low-fluidity, high-strength fluidized solidified soil layer 4 are made of the following materials:

[0032] Soil: Made of waste soil from underground projects, with a moisture content of 30.9%, a liquid limit of 41.3%, and a plastic limit of 20.31%.

[0033] New curing agent: KZJ-H powder curing agent produced by Jiangsu Kunze Technology Co., Ltd.

[0034] The scour pit where the pile foundation 1 is located is in the shape of an inverted frustum, and the riprap layer 2 formed is in the shape of an inverted frustum. The diameter of the horizontal cross-section circle of the riprap layer 2 is 1-2 times the diameter of the pile foundation 1. The median particle size of the riprap in the riprap layer 2 is 240mm-480mm, and the particle size gradation is smooth; the diameter of the high-fluidity, highly dense, fluidized solidified soil layer 3 formed is 1-2 times the diameter of the pile foundation 1; the diameter of the low-fluidity, high-strength fluidized solidified soil layer 4 is 2-3 times the diameter of the pile foundation 1, which can provide good protection and prevent scouring of the protective edge.

[0035] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "front", "back", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in the present invention, it should also be noted that the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, an integrally formed connection, a mechanical connection, or an indirect connection through an intermediate connecting component, and the specific meaning of the terms in this utility model can be understood according to the specific circumstances.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0037] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A construction method for a marine silt solidified soil-riprap mixed anti-scour structure, characterized in that: The anti-scour protection structure is filled in the scour pit where the pile foundation (1) is located, and the structure comprises, from bottom to top, a riprap layer (2), a high-fluidity, highly dense, fluidized solidified soil layer (3), and a relatively low-fluidity, high-strength fluidized solidified soil layer (4). During construction, the riprap layer (2), the high-fluidity, highly dense, fluidized solidified soil layer (3), and the relatively low-fluidity, high-strength fluidized solidified soil layer (4) are filled in sequence. The riprap layer (2), the high-fluidity, highly dense, fluidized solidified soil layer (3), and the relatively low-fluidity, high-strength fluidized solidified soil layer (4) wrap the pile foundation (1); The riprap layer (2) is cast at a certain depth in the scouring pit, the high-fluidity, highly dense fluidized solidified soil (3) is cast based on the self-leveling of the riprap layer (2), and the low-fluidity, high-strength fluidized solidified soil layer (4) is cast based on the self-leveling of the high-fluidity, highly dense fluidized solidified soil (3).

2. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 1, characterized in that: The filling depth of the riprap layer (2) is H s -5d 50 , where H s is the depth of the pit, d 50 is the median particle size of the riprap layer (2).

3. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 2, characterized in that: The filling thickness of the high-fluidity, dense, fluidized solidified soil layer (3) is 2d 50 .

4. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 3, characterized in that: The filling thickness of the relatively low fluidity and high strength fluidized solidified soil layer (4) is 3d 50 .

5. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 2, characterized in that: The scour pit where the pile foundation (1) is located is in the shape of an inverted truncated cone, and the riprap layer (2) formed is in the shape of an inverted truncated cone. The diameter of the horizontal cross-section circle of the riprap layer (2) is 1-2 times the diameter of the pile foundation (1).

6. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 5, characterized in that: The diameter of the formed high-fluidity, highly dense, fluidized solidified soil layer (3) is 1-2 times the diameter of the pile foundation (1).

7. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 2 or 5, characterized in that: The median particle size of the riprap layer (2) is between 240 mm and 480 mm.

8. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 3 or 6, characterized in that: The high-fluidity, high-density fluidized solidified soil layer (3) is formed by combining the following parts: soil, 20 parts; new curing agent, 3 parts; Water, 21 parts.

9. The construction method of a marine silt solidified soil-riprap mixed anti-scour structure according to claim 1 or 4, characterized in that: The low-fluidity and high-strength fluidized solidified soil layer (4) is prepared by combining the following parts: soil, 20 parts; new solidifying agent, 5 parts; Water, 19 parts.

10. The construction method of a marine silt-stabilized soil-riprap mixed anti-scour structure according to claim 1 or 4, characterized in that: The diameter of the relatively low-fluidity and high-strength fluidized solidified soil layer (4) is 2-3 times the diameter of the pile foundation (1).

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