CN112343075B

CN112343075B - Method for reducing settlement of foundation construction of bottom-sitting type jacket of offshore booster station

Info

Publication number: CN112343075B
Application number: CN202011296131.0A
Authority: CN
Inventors: 冯春平; 王小刚; 肖术芳; 庄延军; 苏成; 聂鹏
Original assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd; CGN Power Co Ltd
Current assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd; CGN Power Co Ltd
Priority date: 2020-11-18
Filing date: 2020-11-18
Publication date: 2022-05-31
Anticipated expiration: 2040-11-18
Also published as: CN112343075A

Abstract

The invention provides a method for reducing settlement of foundation construction of a bottom-sitting jacket of an offshore booster station, which comprises the following steps of: s1, arranging a buoyancy device on the basis of the bottom-sitting jacket; s2, hoisting the jacket foundation by using a crane, integrally sinking the jacket foundation and the buoyancy device into the seabed, and performing pile sinking and concrete grouting construction after the jacket foundation is positioned on the mud surface of the seabed; and S3, after the concrete grouting is finished for a period of time and the concrete between the jacket foundation and the pile reaches the expected strength, removing the buoyancy device. The invention provides buoyancy by using the buoyancy device arranged on the booster station foundation, reduces the pressure of the booster station foundation on the seabed mud surface, thereby achieving the purpose of reducing settlement, has the advantages of strong operability, easy implementation of resources, no adverse effect on the body structure, strong applicability and the like, can adjust the buoyancy according to the requirements, and can solve the settlement problem of the bottom-sitting type jacket relatively quickly and at low cost.

Description

Method for reducing settlement of foundation construction of bottom-sitting type jacket of offshore booster station

Technical Field

The invention belongs to the field of foundation construction of offshore booster stations in offshore wind farm engineering, and particularly relates to a method for reducing settlement of foundation construction of a bottom-sitting jacket of an offshore booster station.

Background

The offshore wind farm is an offshore power transmission and transformation facility for collecting electric energy generated by each wind generating set, boosting and sending the electric energy, the offshore boosting station generally comprises a lower foundation and an upper module, the lower foundation supports the upper module, the upper module is integrated with power transmission and transformation equipment, and the lower foundation can be a jacket (a truss component manufactured by a steel structure) or a single pile (a single columnar component manufactured by the steel structure) and other types. The bottom-sitting jacket foundation is a jacket foundation with the bottom sitting on the mud surface of the seabed, and the general construction process comprises the steps of firstly positioning the main structure of the jacket on the mud surface of the seabed, then performing the processes of pile inserting, pile driving, concrete pouring and the like, and hoisting the upper module after the concrete reaches the designed strength.

The offshore booster station is used as a core power transmission and transformation facility of an offshore wind power plant, according to the specification, a first deck of the offshore booster station can not be watered under extreme wind waves which meet 100 years, so that the final elevation of the top of a foundation of the booster station can meet the design requirement, but seabed geological conditions are complex, particularly, floating mud and soft silt often exist on a surface layer, the thickness is not uniform, the bottom of a jacket foundation is large in size, the length and the width generally exceed 30 meters, the weight exceeds 1600 tons, and after a jacket is located on a mud surface, the mud surface is not enough to bear the pressure caused by the jacket, so that jacket foundation settlement can occur. The construction of the offshore booster station needs to ensure that the levelness deviation of each angle of the jacket is in a controllable range, but the existing investigation technical means and design calculation cannot provide an accurate settlement value, so that the settlement value is possibly too large to meet the design requirement.

In the prior art, a method of increasing the design allowance in the elevation direction of a jacket before construction and increasing the height in the elevation direction of the jacket after construction is adopted to avoid that the settlement is too large to meet the design requirement. The design allowance in the jacket elevation direction is increased in advance, so that the problems caused by mud surface water depth measurement errors and inaccurate settlement measurement and calculation are solved preventively, but the jacket height relates to the strength and stability of the whole jacket mechanism, the increase of the design allowance undoubtedly increases the steel consumption and the prefabrication cost, and the increase of the structure size and the weight not only affects the downstream construction investment and the construction difficulty, but also affects the overall strength and the stability. Increase the height on the jacket elevation direction after the construction is the emergency measure after the construction, when finding behind the construction that the jacket top elevation is not enough, add the processing at the jacket top to four stands extension, increase, weld one section the same pipe fitting, but this belongs to emergency measure, has many defects equally: 1) the period of steel material preparation, prefabrication and Shanghai welding needs 2-3 months, and the period cannot bear the schedule of the offshore wind power project; 2) the offshore condition is limited, the construction difficulty is high, and the welding quality risk is high; 3) the height which can be increased needs design accounting, and the height cannot be increased without limit, so that the risk of unsatisfied conditions exists; 4) the investment of materials, ship machines and manpower is large, and the project cost is directly increased.

Therefore, the method for increasing the design allowance in the elevation direction of the jacket before construction and the method for increasing the height of the jacket in the elevation direction after construction have many problems, and the method is not the optimal method for solving the problem that the final elevation of the top of the booster station foundation cannot meet the design requirement due to settlement, and the really effective method is to reduce the settlement of the jacket foundation.

Referring to fig. 1 and 2, in the prior art, a sinking prevention plate is disposed at the bottom of a jacket to increase the contact area with a mud surface, so as to reduce the pressure on the mud surface and further reduce the sinking. However, this method of reducing sedimentation has at least the following disadvantages:

1) with the increase of the area of the anti-sinking plate, the construction difficulty of leveling the jacket foundation is increased, so that the construction quality risk is increased rapidly, and once the standard is exceeded, effective deviation correction is difficult to perform;

2) with the increase of the area of the anti-sinking plate, the steel consumption is increased, for example, about 80 tons of steel plates are put into the anti-sinking plate in a certain project, and the requirements on a transport ship and a crane ship are increased, which directly leads to the increase of project cost;

3) the seabed mud surface of many sea areas "has the floating mud of uneven thickness," and is saturated, flow plastic form, has mobility ", and need evenly set up the wash port on the anti-floating plate, and increase anti-floating plate area can not solve the settlement problem fundamentally.

In view of the above, there is a need to provide a method for reducing settlement of a bottom-standing jacket foundation of an offshore booster station, which can solve the above problems.

Disclosure of Invention

The invention aims to: the method for reducing the construction settlement of the bottom-sitting jacket foundation of the offshore booster station is low in cost and high in practicability, and the problem of the settlement of the bottom-sitting jacket foundation is solved relatively quickly and at low cost.

In order to achieve the above object, the present invention provides a method for reducing settlement of a bottom-sitting jacket foundation construction of an offshore booster station, comprising the steps of:

s1, arranging a buoyancy device on the basis of the bottom-sitting jacket;

s2, hoisting the jacket foundation by using a crane, integrally sinking the jacket foundation and the buoyancy device into the seabed, and performing pile sinking and concrete grouting construction after the jacket foundation is positioned on the mud surface of the seabed;

and S3, after the concrete grouting is finished for a period of time and the concrete between the jacket foundation and the pile reaches the expected strength, removing the buoyancy device.

As an improvement of the method for reducing the construction settlement of the bottom-sitting type jacket foundation of the offshore booster station, the buoyancy device comprises one or more layers of air bags which are uniformly arranged on the jacket foundation.

As an improvement of the method for reducing the settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station, the step S1 includes:

arranging a plurality of lifting lugs on a horizontal stay bar of a first layer of an anti-sinking plate of a jacket foundation in a welding mode;

hoisting the air bag bound by the steel wire rope to an installation position by using a crane, and connecting the air bag with the lifting lug by using a shackle;

and connecting the air bag with an air compressor, and inflating the air bag to a preset pressure by using the air compressor to finish the installation of the air bag.

As an improvement of the method for reducing the settlement of the foundation construction of the bottom-sitting type jacket of the offshore booster station, when the lifting lugs are welded, the welding seam strength is required to be calculated, and the welding positions are required to be protected from corrosion again.

As an improvement of the method for reducing the settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station, the lifting lugs are welded right above the horizontal support rods, and if the sacrificial anode blocks on the horizontal support rods meet, the lifting lugs are welded towards one side of the anti-settling plate in a deviating manner.

As an improvement of the method of the present invention for reducing the settling of the bottom-seated jacket foundation of the offshore booster station, the buoyancy means further includes a spare bladder uniformly disposed on the jacket foundation, the spare bladder being used in step S2 depending on the settling condition of the jacket and being removed together with the bladder conventionally used in step S3.

As an improvement of the method for reducing the settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station, before the step S1, a construction preparation step is further required, which includes:

calculating the total buoyancy required by the air bags, and calculating the specification, the number and the installation positions of the required air bags;

calculating by adopting software, considering the non-uniformity of the stress of the air bag, and considering the load according to a preset non-uniformity coefficient; checking calculation is carried out by combining with construction working conditions, the strength analysis, the anti-slip performance and the anti-overturning performance all need to meet the standard requirements, and settlement is estimated to be used as the reference of a construction stage;

preparing the air bag and related materials for installing and inflating the air bag.

As an improvement of the method for reducing the settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station, the step S2 includes:

hoisting the jacket foundation by using a crane, sinking the jacket foundation and the air bag into the seabed integrally, stabilizing the sinking operation, and monitoring the settlement condition of the jacket at any time;

the jacket foundation is located on the seabed mud surface, and after the jacket is basically stable, a diver is arranged to check to see whether the air bags are firmly connected and the air leakage and pressure maintaining conditions of the air bags, and then pile sinking and concrete grouting construction are carried out, and the diver is required to be arranged to carry out regular inspection in the whole construction process.

As an improvement of the method for reducing the settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station, the step S3 includes:

after the concrete grouting is finished for a period of time, confirming whether the concrete between the jacket foundation and the pile reaches the predicted strength, and if the concrete reaches the predicted strength, carrying out air bag dismantling work;

when the air bag is dismantled, the air bag is matched with a crane, a diver deflates the air bag to reduce the pressure in the air bag, then all shackles between the air bag and the lifting lugs are dismantled, the air bag is lifted to a ship by the crane, and the air bag dismantling work is completed.

As an improvement of the method for reducing the construction settlement of the bottom-sitting type jacket foundation of the offshore booster station, the buoyancy device is a buoy.

Compared with the prior art, the invention provides buoyancy by using the buoyancy device arranged on the booster station foundation, reduces the pressure of the booster station foundation on the seabed mud surface, thereby achieving the purpose of reducing sedimentation, has the advantages of strong operability, easy implementation of resources, no adverse effect on the body structure, adjustable buoyancy according to the requirements, strong applicability and the like, can solve the sedimentation problem of the bottom-sitting type conduit frame relatively quickly and at low cost, is particularly suitable for the offshore booster station which is likely to cause the integral insufficient elevation due to the sedimentation of the booster station foundation, and can effectively ensure that the elevation index can meet the design requirements after construction.

Drawings

The method for reducing settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station and the beneficial technical effects thereof are described in detail below with reference to the accompanying drawings and the specific implementation.

Fig. 1 is a schematic view of a prior art anti-sinking plate arranged at the bottom of a jacket.

Fig. 2 is a schematic plan view of a prior art anti-sink plate disposed at the bottom of a jacket.

Fig. 3 is a flow diagram of a method for settling a foundation of a bottom-supported jacket for an offshore wind power project according to the present invention.

Fig. 4 is a side view of the jacket (without the balloon) of the present invention.

FIG. 5 is a schematic view showing the mounting position of the balloon of the present invention on a catheter holder.

Detailed Description

In order to make the objects, technical solutions and advantageous effects of the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and the detailed description. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

The method for reducing the construction settlement of the bottom-sitting jacket foundation of the offshore booster station comprises the following steps of S1-S3:

s1, arranging a buoyancy device on the basis of the bottom-sitting jacket;

Referring to fig. 3-5, in a preferred embodiment, the buoyancy device is a bladder 10, the bladder 10 may be one or more layers, and is uniformly disposed on the jacket base 20, and in the embodiment shown in fig. 3, the bladder 10 is one layer, and is uniformly disposed on the horizontal struts 22 of the anti-sink plate layer 21 of the jacket base 20. In various embodiments, the bladder 10 may be two or more layers. In addition, the buoyancy means may include spare air bags, which are also uniformly arranged on the jacket foundation structure, in addition to the air bags in use, the specific positions being determined according to the calculation, the spare air bags being used in step S2 depending on the settlement of the jacket and being removed together with the conventionally used air bags in step S3.

The above step S1 is an airbag mounting step, step S2 is a sinking and checking step, step S3 is a finishing dismantling step, and a construction preparation step S0 is required before step S1 is performed. Hereinafter, steps S0 to S3 will be described in detail, taking an offshore wind power project as an example.

The construction preparation step of step S0 specifically includes:

and S01, designing the airbag.

The total buoyancy required by the bladder is accounted for, and the size, number, and mounting location of the required bladders 10 are calculated. In the offshore wind power project, 4 airbags with 50-ton buoyancy are required and are respectively arranged on 4 horizontal supporting rods 22 of one layer 21 of the anti-sinking plate of the jacket foundation (EL. (-)19.910) of the booster station. In addition, 4 air bags with 50 tons of buoyancy are arranged on the internal diamond-shaped supporting tubes of the second layer 24 under the jacket foundation 20 of the booster station to serve as spare air bags (not shown), and the spare air bags are used according to the settlement condition of the jacket in the hoisting process.

The specific fixing mode of the air bag/standby air bag is as follows: after being bound by a steel wire rope net, the air bag 10 is connected to a lifting lug 30 welded on the bottom-sitting type jacket foundation 20 through a shackle, and the lifting lug 30 is welded on a horizontal support rod 22 of a first layer 21 of the anti-sinking plate of the jacket foundation 20 and an internal diamond support tube of a second layer 24 below the anti-sinking plate. Considering the design margin, each air bag is fixed by 12 5t lifting lugs, and the shackle is a 6.5-ton shackle.

And S02, design evaluation.

Calculating a model: and calculating by adopting sac software, respectively adding the calculated values to one layer of the anti-sinking plate and the second layer below the anti-sinking plate according to the consideration of at most 8 air bags, and considering the non-uniformity of the stress of the air bags and the load according to a preset non-uniformity coefficient, for example, 1.2 times.

Sea condition input: and (4) checking calculation is carried out by combining construction working conditions, the wave height is considered according to 2m, and the flow speed is considered according to the maximum tidal flow speed of the surface layer of 0.782 m/s.

And (3) calculating the result: the strength analysis, the anti-slip property and the anti-overturn property all need to meet the standard requirements, and the settlement is estimated to be used as the reference of the construction stage.

And S03, preparing materials.

An air bag: 4 are used by inflation, and 4 are used by non-inflation;

lifting lugs: 96 lifting lugs of 5 t;

and (4) shackle disassembly: 96 shackles of 6.5 t;

steel wire rope: a steel wire rope for hoisting and binding;

an inflation device: compressors, gas lines, etc.

Referring to fig. 4, the step S1 of installing the airbag specifically includes:

and S11, welding a lifting lug. The lifting lugs 30 of the air bags and the spare air bags are arranged on the horizontal supporting rods 22 of the anti-sinking plate layer 21 of the jacket foundation (EL. (-)19.910) and the inner diamond-shaped supporting tubes of the second layer 24 below the jacket foundation 20 of the booster station in a welding mode. The number of the air bags is preferably 4, the materials are rubber, the air bags are respectively connected to 4 horizontal support rods 22 of the anti-sinking plate layer 21, and 12 lifting lugs 5t are welded on each horizontal support rod. The welding needs to be subjected to welding seam strength calculation, the welding position is prevented from being corroded again by attention, the lifting lug 30 is welded right above the horizontal support rod 22, and if a sacrificial anode block on the horizontal support rod is met, the lifting lug is welded to one side of the anti-sinking plate in a deviation mode at a certain angle, and the welding angle is preferably 30 degrees. The number of the standby air bags is also 4, the standby air bags are respectively connected to internal diamond-shaped support pipes of the second layer 24 below the jacket foundation 20 of the booster station, and 12 lifting lugs of 5t are welded on each internal diamond-shaped support pipe.

And S12, connecting the air bag. The air bag 10 is tied up by a crane and a steel wire rope to be lifted to an installation position, and 12 shackles of 6.5t are used for connecting the air bag with the lifting lugs 30; the spare air bag is hoisted in the same manner.

And S13, inflating the air bag. The air bag 10 is connected with an air compressor through an inflation pipeline, and the air compressor is used for inflating the air bag to a preset pressure, so that the air bag installation is completed. The standby airbag is not inflated temporarily.

Step S2 is a sinking and inspecting step, which specifically includes:

and S21, sinking for monitoring. And (3) hoisting the jacket foundation 20 by using a crane, integrally sinking the jacket foundation 20 and the air bag 10 into the seabed, wherein the sinking operation is stable, and the jacket settlement condition is monitored at any time. The standby air bag is used according to the settlement condition of the jacket in the hoisting and settling process.

And S22, testing the air pressure. After the jacket foundation 20 is basically stable, a diver is arranged to check whether the air bag 10 is firmly connected or not and the air leakage and pressure maintaining conditions of the air bag 10, pile sinking and concrete grouting construction are carried out, and the diver is required to carry out regular inspection in the whole construction process.

Step S3 is a finishing demolition step, specifically including:

s31, after the concrete grouting is finished for a certain period of time (e.g., after 3 days), it is confirmed whether the concrete between the jacket foundation 20 and the pile has reached the expected strength, and the air bag removal work is performed only if the expected strength is reached.

And S32, when the air bag 10 is detached, a crane is used for matching, a diver deflates the air bag 10 to reduce the pressure in the air bag 10, then all shackles between the air bag 10 and the lifting lugs 30 are detached, and the air bag is lifted to a ship by using the crane to finish the air bag detachment work. And simultaneously, the standby air bag is removed.

The above description is based on that the jacket of the offshore booster station has been prefabricated, and the jacket of the offshore booster station is sunk to have larger settlement according to the judgment of the construction condition of the wind turbine foundation near a nearby wind field or the local wind field, so as to solve or reduce the emergency measures of settlement. When the design stage judges that the measure is needed, the design can be carried out in the construction drawing design stage by directly referring to the scheme, the lifting lugs and the paint are made in the prefabrication stage, and the construction stage is implemented according to the air bag.

In other embodiments, the air bag may be replaced with other types of buoyancy devices, such as buoys of different materials, but consideration should be given to the applicable water depth, whether the buoyancy is adjustable, whether installation is convenient, and damage to permanent structures such as collision and extrusion is avoided.

The invention provides buoyancy by using the buoyancy device arranged on the booster station foundation, reduces the pressure of the booster station foundation on the seabed mud surface, thereby achieving the purpose of reducing settlement, has the advantages of strong operability, easy implementation of resources, no adverse effect on the body structure, adjustable buoyancy according to the requirement, strong applicability and the like, can solve the problem of settlement of the construction of the bottom-sitting type jacket foundation relatively quickly and at low cost, is particularly suitable for the offshore booster station with insufficient overall elevation possibly caused by the settlement of the booster station foundation, and can effectively ensure that the elevation index after construction can reach the design requirement.

The present invention can be modified and adapted appropriately from the above-described embodiments, according to the principles described above. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A method for reducing settlement of foundation construction of a bottom-sitting jacket of an offshore booster station is characterized by comprising the following steps:

step S1, arranging an air bag as a buoyancy device on the basis of the bottom-sitting type jacket; the buoyancy device comprises one or more layers of air bags, and the air bags are uniformly distributed on the basis of the jacket;

step S2, hoisting the jacket foundation by using a crane, integrally sinking the jacket foundation and the buoyancy device into the seabed, and performing pile sinking and concrete grouting construction after the jacket foundation is positioned on the mud surface of the seabed;

step S3, after the concrete grouting is finished for a period of time, confirming whether the concrete between the jacket foundation and the pile reaches the predicted strength, and if the concrete reaches the predicted strength, carrying out air bag dismantling work; when the air bag is dismantled, the air bag is matched by a crane, a diver deflates the air bag to reduce the pressure in the air bag, then all shackles between the air bag and the lifting lugs are dismantled, and the air bag is lifted to a ship by the crane to complete the dismantling work of the air bag;

the step S1 includes:

arranging a plurality of lifting lugs on a horizontal stay bar of a first layer of an anti-sinking plate of a jacket foundation in a welding mode; the lifting lug is welded right above the horizontal support rod, and if a sacrificial anode block on the horizontal support rod is encountered, the lifting lug is welded towards one side of the anti-sinking plate in a deviation way;

2. The method for reducing the settlement of the foundation construction of the bottom-sitting jacket of the offshore booster station according to claim 1, wherein the welding of the lifting lugs requires the calculation of the strength of the welding line and the prevention of corrosion of the welding position.

3. The method for reducing the settling of the foundation of the submersible jacket of the offshore booster station according to claim 1, wherein the buoyancy means further comprises a backup bladder uniformly disposed on the jacket foundation, the backup bladder being used in step S2 depending on the settling of the jacket and being removed together with a conventionally used bladder in step S3.

4. The method for reducing the settlement of the foundation of the marine booster station bottom-sitting jacket according to claim 1, wherein before performing step S1, a construction preparation step is further performed, comprising:

calculating by adopting software, considering the non-uniformity of the stress of the air bag, and considering the load according to a preset non-uniformity coefficient; checking calculation is carried out by combining construction working conditions, the strength analysis, the slippage resistance and the overturn resistance all need to meet the standard requirements, and settlement is estimated to be used as the reference of a construction stage;

5. The method for reducing settlement of the foundation construction of the submersible jacket of the offshore booster station according to claim 1, wherein the step S2 comprises:

hoisting the jacket foundation by using a crane, sinking the jacket foundation and the air bag into the seabed integrally, wherein the sinking operation is stable, and monitoring the jacket settlement condition at any time;