阅读说明：本技术 一种适用于有淤泥覆盖层海床的海上风电复合基础及施工方法 (Offshore wind power composite foundation suitable for seabed with sludge covering layer and construction method ) 是由 吴敬凯 闫俊义 王卫 于 2020-07-28 设计创作，主要内容包括：本发明公开了一种适用于有淤泥覆盖层海床的海上风电复合基础及施工方法,所述海上风电复合基础是一种桩基础和重力式支撑结构联合形成的基础型式,所述适用于有淤泥覆盖层海床的施工方法是采用深层搅拌法,直接将桩基础周围的淤泥胶结固化成重力式支撑结构,重力式支撑结构与桩基础共同承担外部载荷。本发明的施工方法可以有效解决现有海上风电复合基础很难适用于有较厚淤泥覆盖层的海床,因此不得不采用超大直径超长单桩基础、嵌岩桩基础、多桩基础和导管架基础以及由此带来的施工难题。该施工方法简单可行,成本较低,能够使桩基础适用于水深30~60m海域和更复杂的浅覆盖层海床地质条件。(The invention discloses an offshore wind power composite foundation suitable for a seabed with a sludge covering layer and a construction method thereof. The construction method can effectively solve the problems that the existing offshore wind power composite foundation is difficult to be suitable for the seabed with a thick sludge covering layer, and therefore an ultra-large-diameter ultra-long single-pile foundation, a rock-socketed pile foundation, a multi-pile foundation and a jacket foundation have to be adopted, and the construction difficulty is caused by the ultra-large-diameter ultra-long single-pile foundation, the rock-socketed pile foundation, the multi-. The construction method is simple and feasible, has low cost, and can enable the pile foundation to be suitable for the seabed geological conditions of the sea area with the water depth of 30-60 m and more complex shallow covering layers.)

1. The offshore wind power composite foundation is suitable for a seabed with a sludge covering layer, and is characterized by comprising a pile foundation (1) and a gravity type supporting structure (2), wherein the pile foundation (1) is a main bearing structure, and the gravity type supporting structure (2) improves the horizontal bearing capacity of the composite foundation; the pile foundation is in a foundation type with piles as bearing structures; the gravity type supporting structure (2) provides horizontal resistance for the pile foundation (1) on the bearing layer (4), and the gravity type supporting structure (2) is located inside the silt layer (3).

2. The offshore wind power composite foundation applicable to seabed with a sludge blanket as claimed in claim 1, wherein: the pile foundation in the offshore wind power composite foundation is a single-pile foundation with the diameter of 5-12 m, a multi-pile foundation or a jacket pile foundation with the anchoring structure with the diameter of 1-3 m.

3. The method for constructing an offshore wind power composite foundation suitable for a seabed covered with a sludge blanket as claimed in any one of claims 1 to 2, wherein: and directly cementing and curing the sludge around the pile foundation (1) into a gravity type supporting structure (2) by adopting a deep stirring method, wherein the gravity type supporting structure (2) formed by cementing and curing the sludge is positioned on the surface of a bearing layer below the sludge layer, and the pile foundation and the gravity type supporting structure are connected in a fixed connection or a sliding connection mode.

4. The method for constructing an offshore wind power composite foundation suitable for a seabed covered with a sludge blanket as claimed in claim 3, wherein: the construction method further comprises the step of cementing and solidifying sludge and a supporting layer soil body around the pile foundation (1) into the gravity type supporting structure (2) by adopting a deep layer stirring method, wherein the gravity type supporting structure (2) formed by cementing and solidifying is positioned in the supporting layer, and the pile foundation and the gravity type supporting structure are fixedly connected or in sliding connection.

Technical Field

The invention relates to the technical field of offshore wind power, in particular to a construction method of an offshore wind power composite foundation suitable for a seabed with a sludge covering layer.

Background

At present, common foundation types of offshore wind farms include gravity foundations, mono-pile foundations and jacket foundations. The single pile has the advantages of high construction speed, low engineering cost, strong foundation applicability and the like, and the proportion of the single pile in the installed foundation exceeds 80 percent. With the gradual trend of offshore wind power plants from offshore to deep and offshore and the continuous increase of the capacity of wind generating sets, the external load required to be borne by the foundation structure is remarkably increased, especially the horizontal load formed by coupling wind, waves, ocean currents and ice, so that the pile diameter, the pile length and the pile weight of a single-pile foundation are increased, and the foundation cost and the construction difficulty are increased. According to statistics, the proportion of the offshore wind power foundation and the installation cost thereof to the total investment cost is 20-40%. However, the vertical bearing capacity of the offshore wind power single-pile foundation is often higher than the design requirement, and the horizontal bearing capacity is insufficient, so that the requirements of the horizontal bearing capacity are met by continuously increasing the pile diameter and the pile length, huge waste of the vertical bearing capacity can be caused, and the offshore construction operation difficulty is greatly increased.

In recent years, researchers have proposed the idea of offshore wind power composite foundation, including a truncated cone auxiliary reinforced single-pile foundation of An offshore wind power generation unit and a construction method (application number: 201910633296.3), An offshore wind power unit reinforced composite single-pile foundation and a construction method (application number: 201910633302.5), and a novel offshore wind power composite single-pile foundation (paper name: innovation on offset with turbine and with An innovative hybrid foundation). The offshore wind power composite foundation is a single-pile foundation assisted by a gravity type supporting structure, so that the bearing performance of the composite foundation is improved, and the foundation cost is reduced. In the technical scheme of the offshore wind power composite foundation, a gravity type supporting structure is arranged around a single-pile foundation and is positioned on a muddy water interface, namely the interface of a pile body soil body inserting section and a soil body exposing section. However, the geological conditions of the sea areas such as Fujian and Guangdong, which are the most abundant wind resources in China, are deep and shallow covering layers, and a sludge layer with the thickness of 3-15 m is arranged above the covering layers. The silt layer is composed of silt and silt silty clay, and geotechnical tests show that the silt and the silt silty clay have high water content, low shear strength, strong compressibility, poor permeability and no bearing capacity. Therefore, the offshore wind power composite foundation is not suitable for the seabed with a silt covering layer, and the machine position of the existing shallow bearing stratum usually needs to adopt a rock-socketed pile foundation and a jacket foundation with higher construction cost and construction difficulty. Based on the above, a construction method suitable for the sea wind power composite foundation and suitable for the seabed with a sludge covering layer is urgently needed, a gravity type supporting structure is directly formed above the pile peripheral supporting layer of the single-pile foundation, the horizontal bearing capacity of the single-pile foundation is improved, the construction cost is reduced, and the cost reduction and the efficiency improvement of the sea wind power are realized.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention provides a construction method of an offshore wind power composite foundation suitable for a seabed with a sludge covering layer, the construction method can be suitable for seabed geological conditions with a thick sludge layer on the upper part of the covering layer, and a gravity type supporting structure is formed by cementing and solidifying the sludge layer above a bearing layer, so that the bearing capacity of a pile foundation is improved. In addition, the construction method can enable the single-pile foundation to be suitable for sea areas with water depths of 30-60 m and more complex seabed geological conditions of shallow covering layers.

In order to achieve the technical features, the invention is realized as follows: an offshore wind power composite foundation is suitable for a construction method of a seabed with a sludge covering layer, the offshore wind power composite foundation consists of a pile foundation and a gravity type supporting structure, the pile foundation is a main bearing structure, and the gravity type supporting structure improves the horizontal bearing capacity of the composite foundation; the pile foundation is in a foundation type with piles as bearing structures; the gravity type supporting structure provides horizontal resistance for the pile foundation on the bearing layer, and is located inside the sludge layer.

The pile foundation in the offshore wind power composite foundation is a single-pile foundation with the diameter of 5-12 m, a multi-pile foundation or a jacket pile foundation with the anchoring structure with the diameter of 1-3 m.

And directly cementing and curing the sludge around the pile foundation into a gravity type supporting structure by adopting a deep stirring method, wherein the gravity type supporting structure formed by cementing and curing the sludge is positioned on the surface of a bearing layer below the sludge layer, and the pile foundation and the gravity type supporting structure are connected in a fixed connection or a sliding connection mode.

The construction method further comprises the step of cementing and solidifying sludge and a supporting layer soil body around the pile foundation into a gravity type supporting structure by adopting a deep layer stirring method, wherein the gravity type supporting structure formed by cementing and solidifying is positioned in the supporting layer, and the pile foundation and the gravity type supporting structure are fixedly connected or slidably connected.

The invention has the following beneficial effects:

1. the invention directly cements and solidifies the silt and silty clay near the periphery of the pile and above the bearing layer into the gravity type supporting structure, thereby improving the bearing capacity of the pile foundation, especially the horizontal bearing capacity, and solving the technical problem that the gravity type supporting structure can not be directly placed on the silt layer or can hardly pass through the thicker silt layer to be placed on the surface of the bearing layer in the existing offshore wind power composite foundation technology.

2. The construction method can enable the single-pile foundation to be suitable for sea areas with water depths of 30-60 m and more complex seabed geological conditions of shallow covering layers.

3. The invention utilizes the mature pile foundation construction process and the soft soil foundation reinforcement construction process, and only needs to improve the soft soil foundation construction process, so that the soft soil foundation construction process can be better suitable for reinforcing the sludge around the pile foundation, and the research cost and the construction cost are effectively reduced.

4. The construction method mainly aims at cementing and curing the sludge above the bearing stratum, and the gravity type supporting structure formed by cementing and curing the sludge is positioned at the lower part of the sludge stratum, so that the bottom of the gravity type foundation is effectively prevented from being washed by wave current and ocean current.

Drawings

The invention is further illustrated by the following figures and examples.

FIG. 1 is a schematic diagram of an offshore wind power composite infrastructure in an embodiment of the invention.

In the figure: 1 pile foundation, 2 gravity type bearing structures, 3 silt layers and 4 bearing layers.

Detailed Description

Embodiments of the present invention will be further described with reference to the accompanying drawings.

Fig. 1 is an embodiment of a construction method for applying the offshore wind power composite foundation of the present invention to a seabed with a sludge covering layer, the offshore wind power composite foundation is composed of a pile foundation 1 and a gravity type supporting structure 2, the pile foundation 1 is a main bearing structure, the gravity type supporting structure 2 is an auxiliary structure, the gravity type supporting structure 2 mainly serves to improve the horizontal bearing capacity of the composite foundation, and the pile foundation 1 is a large-diameter single pile foundation.

The construction method that the offshore wind power composite foundation is suitable for the seabed with the silt covering layer is characterized in that a deep stirring method is adopted, silt and silt silty clay around the pile foundation 1 are directly cemented and cured to form the gravity type supporting structure 2, the gravity type supporting structure 2 formed by cementing and curing of the silt is positioned on the surface of a holding layer 4 below a silt layer 3, the pile foundation 1 and the gravity type supporting structure 2 are fixedly connected or slidably connected, a cementing material adopted by the deep stirring method is cement paste or a chemical curing agent, the holding layer 4 is a sand soil layer or a clay layer, the soil body of the clay layer comprises clay, silty clay and the like, and the sand soil body comprises silt, medium coarse sand, gravel and the like.

It can be understood that the pile foundation 1 in the embodiment of the invention is a single-pile structure type commonly used for offshore wind power, such as a large-diameter hollow steel pipe pile, a steel-concrete composite pile and the like. The gravity type supporting structure 2 formed by cementing and curing the sludge is a continuous body formed by continuous construction around a pile body so as to ensure the uniformity of cementing and the consistency of curing strength, and the size, the strength and the shape of the gravity type supporting structure 2 depend on the horizontal bearing capacity of a composite foundation, the construction cost, the construction speed and the pile foundation type. The gravity type supporting structure 2 is preferably in a circular truncated cone shape, the thickness of the gravity type supporting structure is 2-5 m, and the maximum diameter of the bottom of the circular truncated cone is 1.5-3 times of the pile diameter.

It will be appreciated that when the pile foundation 1 is fixedly connected to the gravity support structure 2, the gravity support structure 2 not only provides horizontal load bearing but also can bear part of the vertical load. When the connection mode of the pile foundation 1 and the gravity type supporting structure 2 is sliding connection, the pile foundation 1 can move up and down in the center of the gravity type supporting structure 2, and the gravity type supporting structure 2 can only provide horizontal bearing capacity to prevent the horizontal deformation of the pile foundation 1.

It should be noted that the pile foundation 1 can be a single pile foundation with a diameter of 5-12 m, a multi-pile foundation, a jacket pile foundation with an anchoring structure with a diameter of 1-3 m, and other foundation types with piles as a bearing structure.

Specifically, the construction method further comprises the step of cementing and solidifying the sludge and the soil body of the supporting layer in the area around the pile of the pile foundation 1 into a gravity type supporting structure by adopting a deep layer stirring method, wherein the gravity type supporting structure formed by cementing and solidifying is positioned in the supporting layer 4.

It can be understood that, simultaneously, the soil body of the holding layer is consolidated and solidified, so that on one hand, the friction action between the bottom of the gravity type supporting structure and the holding layer can be fully utilized, the horizontal bearing capacity of the composite foundation is improved, and on the other hand, the gravity type supporting structure caused by the surface fluctuation of the holding layer is prevented from inclining.

It is worth explaining that for a seabed without sludge, the construction method provided by the invention can be adopted to directly perform cementation and solidification on a soil body of a bearing layer to form a gravity type supporting structure, and the method can effectively solve the problems of overlong single-pile foundation pile and overlarge pile diameter in a deep and long sea offshore wind power plant and the construction difficulty caused by the overlong pile length.