Construction process of offshore wind power foundation implanted rock-socketed single pile
Technical Field
The invention relates to a construction process of an implanted rock-socketed single pile of an offshore wind power foundation.
Background
In the field of offshore wind power plant foundation design, comprehensive division is carried out according to different stratum structures and characteristics, and according to the cause types and engineering characteristics of various rock-soil layers, and the commonly adopted single-pile foundation comprises a non-rock-socketed single pile, a rock-socketed single pile and an implanted rock-socketed single pile. The construction of the pile foundation is a first-aid project of an offshore wind power project, offshore wind power construction is carried out on an open sea non-shield area which is far away from land and has the water depth of 16-19 m, the pile foundation is restrained by natural conditions such as weather, tide, waves and the like and is also in a tropical storm frequent area, and fan equipment has high requirements on bearing, uplift resistance and deformation of the foundation, so that the required pile foundation has a large diameter and a deep soil penetration depth, the fan foundation can bear huge fan overturning moment and bear wave and water load, and the construction period control of the construction progress is particularly critical.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a construction process of an implanted rock-socketed single pile of an offshore wind power foundation, which can improve the construction efficiency, effectively improve the horizontal resistance and the poking resistance of the rock-socketed pile and meet the requirements of engineering structure design and construction.
The purpose of the invention is realized as follows: a steel pipe pile with the diameter of 6.7m and the wall thickness of 60-80 mm is adopted for a single pile related to the construction process of an implanted rock-socketed single pile of an offshore wind power foundation, the steel pipe pile is driven into fractured strongly weathered granite, the total depth of penetration is 22.9-27.6 m, the pile top elevation is 15m, and the pile bottom elevation is about minus 43-minus 46 m;
the construction process comprises the following steps: manufacturing a steel pipe pile and a steel pile casing, building a stable pile platform, inserting the steel pile casing, vibrating the steel pile casing, drilling, cleaning holes, implanting the steel pipe pile, pouring bottom sealing concrete, backfilling and grouting the outer wall of the pile and recovering the steel pile casing; wherein,
the manufacturing process of the steel pipe pile and the steel casing comprises the steps of blanking of a pipe joint, processing of a pipe joint groove, rolling and forming of the pipe joint, assembling of a flange at the top of a pile body, splicing of the pile body and coating of an anticorrosive coating;
the pile stabilizing platform erection process comprises the following steps:
the lower platform and the four auxiliary process piles are positioned through the relative positions of the positioning platform ship and steel pipe piles at the closure of the lower platform, then the four auxiliary process piles are inserted and driven, and then the auxiliary process piles and the upper and lower parts of auxiliary process pile sleeves on the lower platform are firmly welded through steel plate strips;
moving away the positioning platform ship, inserting and driving two positioning process piles, and firmly welding the positioning process piles with the upper and lower parts of a positioning process pile sleeve on the lower platform through steel plate strips;
thirdly, installing an upper platform after the ③ steel casing insertion process is finished;
the steel casing inserting process comprises the following steps:
firstly, processing a lower platform of a pile stabilizing platform into a guide frame platform, wherein the center of the guide frame platform is the center of the steel pipe pile;
lifting the steel casing to a guide frame platform by the auxiliary lifting boat and slowly falling into the guide frame platform, stopping sinking when the steel casing passes through a lower platform of the guide frame platform, measuring the verticality of the steel casing by two leveling rulers, and tightly holding the steel casing at the bottom layer of the guide frame platform by a hydraulic jack after the verticality meets the requirement, and slowly sinking;
measuring and rechecking the verticality of the steel casing when the steel casing is sunk to the mud surface junction, continuing to sink to be stable after meeting the requirement, sleeving the steel casing with a hydraulic four-linkage vibrating hammer at the top of the steel casing, lifting the hydraulic four-linkage vibrating hammer with an auxiliary crane ship, vibrating and sinking the steel casing, and rechecking the verticality of the steel casing when the penetration of the steel casing reaches the hammer stopping standard, and then reinforcing the connection between the steel casing and the guide frame platform after the hammer is stopped and the verticality of the steel casing is rechecked;
the drilling process comprises the steps of positioning a drilling machine, installing a drill rod, preparing slurry and drilling to form a hole;
when the drilling machine is in place, firstly hanging away a hydraulic four-linkage vibration hammer, then erecting the drilling machine, adopting a gas-lift reverse circulation hydraulic power drilling machine provided with a hob bit, and locking the drilling machine and the steel casing through a pile gripper;
when the step of installing the drill rod is carried out, the drill bit and the drill rod are assembled on a deck of the main crane ship and then installed on the drilling machine;
when the step of preparing the slurry is carried out, the retaining wall slurry adopts the PHP high-performance slurry which is not dispersed, has low solid phase and high viscosity, firstly the bentonite slurry is stirred by a slurry stirrer in a slurry pool, then the bentonite slurry is pumped into the steel retaining cylinder by a slurry pump, and when the performance index of the slurry in the steel retaining cylinder meets the construction requirement, a hole is drilled;
when the drilling hole forming step is carried out, when a drilling machine starts drilling, the diameter of the drilled hole is increased from small to large, a small hole is drilled when the upper part is looser soil layer, the diameter of the drilled hole is more than 200mm smaller than the inner diameter of the steel pipe pile, the diameter of the drilled hole is expanded when the lower part is hard rock layer, and the diameter of the drilled hole is 100-200 mm larger than the inner diameter of the steel pipe pile;
during the hole cleaning process, lifting the drilling tool to be 30-50 cm away from the bottom of the hole, slowly rotating the drilling tool, supplementing high-quality slurry, performing reverse circulation hole cleaning, and simultaneously keeping a water head in the hole to prevent hole collapse;
when the steel pipe pile implanting process is carried out, firstly, a drilling machine is moved away, the steel pipe pile is hoisted and erected from a transport pile in a lifting and hanging mode of matching a main crane ship and an auxiliary crane ship, the steel pipe pile is placed into a steel casing through the main crane ship, then the steel pipe pile is positioned to the pile center position of the steel casing through a positioning system, then a jack on a lower platform is adopted to hold the steel pipe pile tightly, the center deviation of the steel pipe pile is confirmed to be within an error, the steel pipe pile is slowly lowered by the main crane ship after the verticality of the steel pipe pile meets the requirement, until the steel pipe pile stops sinking, then a hydraulic pile driving hammer is sleeved at the top of the steel pipe pile, after the steel pipe pile sinks to be stable, the hydraulic pile driving hammer slowly hammers a pile top tool flange with small energy, and the striking energy of the hydraulic pile driving hammer is increased from small energy to high energy until the steel;
when the bottom sealing concrete pouring process is carried out, the height of the bottom sealing is 1.5m, C40 underwater undispersed concrete is adopted, and a vertical guide pipe method is adopted for carrying out three-point pouring, wherein the three-point pouring comprises the steps of guide pipe installation, secondary hole cleaning, underwater concrete pouring and secondary pouring;
when the pile outer wall backfill grouting process is carried out, grouting is carried out between the outer wall of the bottom of the steel pipe pile and rock soil;
and when the steel protection cylinder recycling process is carried out, the steel protection cylinder is pulled out through a hydraulic four-linkage vibration hammer.
According to the construction process of the offshore wind power foundation implanted rock-socketed single pile, before the drilling and hole forming step of the drilling process is completed, high-pressure jet grouting pile construction is performed to prevent hole collapse; the high-pressure rotary jet grouting pile construction comprises the working procedures of drilling, lower jet pipe, jetting and pile forming; the inner diameter phi of the drilled hole is 600mm, the drilled hole is annularly arranged along the inner wall 300mm of the steel casing with the inner diameter phi of 750mm, and adjacent holes are lapped by 100 mm; when in rotary spraying, the spraying pressure is 0.6-0.8 MPa, and the spraying flow is 0.8-1.2 m 3/min; the lifting speed of the jet pipe is 10-15 cm/min, and the rotating speed of the jet pipe is 10-15 r/min.
According to the construction process of the offshore wind power foundation implantation type rock-socketed single pile, when the steel pipe pile implantation process is carried out, a pile top tool flange is installed at the top of the steel pipe pile, is of an L-shaped cross section structure, and is tightly attached and connected with the pile top flange through a connecting bolt.
In the construction process of the offshore wind power foundation implanted rock-socketed single pile, when the guide pipe installation step of the bottom sealing concrete pouring process is carried out, an operation platform is firstly erected at the top of the steel pipe pile, and three guide pipes with the inner diameter of 300mm and three grouting material hoppers connected with the tops of the three guide pipes are installed on the operation platform; the three guide pipes are arranged in the pile hole in an equilateral triangle manner by connecting the centers of the three guide pipes, the side length of each equilateral triangle is equal to the flowing radius of the concrete by 2.5-4.0 m, and the distance from the bottom end of each guide pipe to the bottom of the pile hole is 30-50 cm; when the secondary hole cleaning step is carried out, firstly, the air pipe is put into the guide pipe, the upper part of the air pipe is connected with an air pipe of the air compressor through a special joint, and the special joint is connected with the guide pipe; lifting the guide pipe to a certain height, wherein the height is determined according to the deposition thickness of the bottom of the pile hole, then starting an air compressor to supply air, slowly lowering the guide pipe while circulating after the air lift reverse circulation is normal until the guide pipe is lowered to the bottom of the pile hole, and removing sediment at the bottom of the pile hole when the sand content in the discharged slurry meets the requirement; when the underwater concrete pouring step is carried out, the concrete is mixed on site and then is pumped into the guide pipe, and pouring is carried out from the bottom of the hole upwards; and when the secondary driving step is carried out, a hydraulic pile driving hammer is adopted to drive the steel pipe pile to the designed elevation before the initial setting of the concrete.
In the construction process of the offshore wind power foundation implanted rock-socketed single pile, when the backfill grouting process of the outer wall of the pile is carried out, four sets of grouting systems are arranged, and each set of grouting system comprises four grouting pipes and four grout return pipes; during grouting, firstly, grouting is carried out on a pile end grouting system, a grout return pipe is plugged when the grout return pipe discharges grout, grouting is carried out on the grouting pipe continuously until the rated grouting pressure is reached, and grouting is stopped and a grouting opening is plugged after the grouting flow is less than 2L/min and maintained for 0.5h under the rated grouting pressure or when the grouting flow is suddenly increased and the grouting pressure is suddenly reduced in the grouting process.
The construction process of the offshore wind power foundation implanted rock-socketed single pile adopts the pile stabilizing platform for auxiliary positioning, adopts the steel casing for rock-socketed construction, adopts the main crane ship and the auxiliary crane ship to be matched to lift and insert the steel pipe pile into the steel casing, can efficiently finish pile sinking construction, is also provided with the appropriate hammering equipment and drilling equipment, monitors and adjusts the posture of the steel pipe pile in the whole course to ensure that the single pile is smoothly and vertically driven into a seabed rock layer, simultaneously adopts targeted measures to keep the hole wall stable, prevents abnormal conditions such as drill jamming, drill burying and the like, ensures the bearing capacity and the stability of a pile body of the rock-socketed single pile, effectively improves the construction efficiency, effectively improves the horizontal resistance and the anti-pulling capacity of the rock-socketed pile, and meets the requirements of engineering structure design and construction.
Drawings
FIG. 1 is a flow chart of the construction process of the offshore wind power foundation implanted rock-socketed mono-pile of the present invention;
FIG. 2a is a front view of a pile stabilizing platform adopted in the construction process of the offshore wind power foundation implanted rock-socketed single pile;
figure 2b is a schematic plan view of the upper deck of the lower deck of the pile stabilized platform of the present invention;
figure 2c is a schematic plan view of the lower one of the lower platforms of the pile stabilized platform of the present invention;
FIG. 3 is a state diagram of the construction process of the offshore wind power foundation implanted rock-socketed single pile during the steel pipe pile implantation process;
FIG. 4 is a schematic structural diagram of a grouting system adopted in the bottom-sealing concrete pouring process of the offshore wind power foundation implanted rock-socketed mono-pile construction process of the invention;
FIG. 5 is a layout diagram of a guide pipe during a bottom sealing concrete pouring process of the offshore wind power foundation implanted rock-socketed mono-pile construction process;
FIG. 6 is a schematic diagram of a grouting position during a pile outer wall backfill grouting process of the offshore wind power foundation implanted rock-socketed single pile construction process.
Detailed Description
The invention will be further explained with reference to the drawings.
Referring to fig. 1 to 6, according to the construction process of the offshore wind power foundation implanted rock-socketed mono-pile, a steel pipe pile with the diameter of 6.7m and the wall thickness of 60-80 mm is adopted, and is driven into the disintegrated strong weathering granite, the total soil penetration depth is 22.9-27.6 m, the pile top elevation is 15m, and the pile bottom elevation is about minus 43-minus 46 m.
The construction process of the offshore wind power foundation implanted rock-socketed single pile comprises the following steps: manufacturing a steel pipe pile and a steel pile casing, building a stable pile platform, inserting the steel pile casing, vibrating the steel pile casing, drilling, cleaning holes, implanting the steel pipe pile, pouring bottom sealing concrete, backfilling and grouting the outer wall of the pile and recovering the steel pile casing.
The manufacturing process of the steel pipe pile and the steel casing comprises the steps of pipe joint blanking, pipe joint groove processing, pipe joint rolling forming, pile body top flange assembling, pile body splicing and anticorrosive coating.
The pile stabilizing platform 10 comprises an upper platform 12, a lower platform 11, four auxiliary process piles 13, two positioning process piles 14, an outer keel beam 15 and a set of positioning system consisting of twelve 100T jacks 20; the lower platform 11 is composed of an upper platform 111 and a lower platform 112, seven jacks 20 are arranged on the upper platform 111 around the closure, and five jacks 20 are arranged on the lower platform 112 around the closure and staggered with the seven jacks 20 on the upper platform 111; the outer keel beam 15 is installed at the keel of the upper deck 111 after the steel pipe pile 100 is inserted into the keel (see fig. 2a to 2 c).
The pile stabilizing platform building process comprises the following steps:
the lower platform and the four auxiliary process piles are positioned through the relative positions of the positioning platform ship and steel pipe piles at the closure of the lower platform, then the four auxiliary process piles are inserted and driven, and then the auxiliary process piles and the upper and lower parts of auxiliary process pile sleeves on the lower platform are firmly welded through steel plates;
moving away the positioning platform ship, inserting and driving two positioning process piles, and firmly welding the positioning process piles with the upper and lower parts of a positioning process pile sleeve on the lower platform through steel plate strips;
and thirdly, installing an upper platform after the ③ steel casing insertion process is finished so as to carry out rock-socketed construction.
The steel casing inserting process comprises the following steps:
firstly, processing a lower platform of a pile stabilizing platform into a guide frame platform, wherein the center of the guide frame platform is the center of the steel pipe pile;
lifting the steel casing to a guide frame platform by the auxiliary lifting boat and slowly falling into the guide frame platform, stopping sinking when the steel casing passes through a lower platform of the guide frame platform, measuring the verticality of the steel casing by two leveling rulers, and tightly holding the steel casing at the bottom layer of the guide frame platform by a hydraulic jack after the verticality meets the requirement, and slowly sinking;
and thirdly, when the steel pile casing sinks to the mud surface junction, measuring and rechecking the verticality of the steel pile casing, continuing to sink to be stable according to the requirement, sleeving the hydraulic four-linkage vibration hammer at the top of the steel pile casing, lifting the hydraulic four-linkage vibration hammer by an auxiliary crane ship, vibrating and sinking the steel pile casing, waiting for the penetration of the steel pile casing to reach the standard of stopping the hammer, rechecking the verticality of the steel pile casing by stopping the hammer, and meeting the design requirement and then reinforcing the connection between the steel pile casing and the guide frame platform.
The drilling process comprises the steps of positioning a drilling machine, installing a drill rod, preparing slurry and drilling to form a hole;
when the drilling machine is in place, firstly hanging away a hydraulic four-linkage vibration hammer, then erecting the drilling machine, adopting a gas-lift reverse circulation hydraulic power drilling machine provided with a hob bit, locking the drilling machine and a steel casing through a pile gripper, and ensuring that the center of the drilling machine bit and the center of the steel casing are on the same plumb line, wherein the deviation is not more than 10 cm;
during the step of installing the drill rod, during initial drilling, the drill bit consists of a heavy balancer and a heavy drill rod; the drill bit and the drill rod are assembled on a deck of the main crane ship and then are installed on the drilling machine, and in the drilling process, the second section of drill rod and the subsequent drill rods are directly installed on a platform of the main crane ship;
when the step of preparing the slurry is carried out, the retaining wall slurry adopts the PHP high-performance slurry which is not dispersed, has low solid phase and high viscosity, firstly the bentonite slurry is stirred by a slurry stirrer in a slurry pool, then the bentonite slurry is pumped into the steel retaining cylinder by a slurry pump, and when the performance index of the slurry in the steel retaining cylinder meets the construction requirement, a hole is drilled;
when the drilling pore-forming step is carried out, a slurry retaining wall is adopted, water is timely supplemented into the steel retaining cylinder, and the water head difference between the inside and the outside of the steel retaining cylinder is kept; when a drilling machine starts to drill holes, the diameter of the drilled holes is increased from small to large, small holes are drilled when the upper part of the drilled holes is looser than a loose soil layer, the diameter of the drilled holes is required to be more than 200mm smaller than the inner diameter of the steel pipe pile so as to ensure the vertical bearing capacity of the steel casing, the diameter of the drilled holes is required to be enlarged when the drilled holes meet a hard rock layer at the lower part, and the diameter of the drilled holes is 100-200 mm larger;
before the drilling and hole forming step, in order to prevent hole collapse, high-pressure jet grouting pile construction is firstly carried out, wherein the high-pressure jet grouting pile construction comprises the working procedures of drilling, lower jet pipe injection and pile forming; the inner diameter phi of the drilled hole is 600mm, the drilled hole is annularly arranged along the inner wall 300mm of the steel casing with the inner diameter phi of 750mm, and adjacent holes are lapped by 100 mm; when in rotary spraying, the spraying pressure is 0.6-0.8 MPa, and the spraying flow is 0.8-1.2 m 3/min; the lifting speed of the jet pipe is 10-15 cm/min, and the rotating speed of the jet pipe is 10-15 r/min.
When the hole cleaning process is carried out, lifting the drilling tool to be 30-50 cm away from the bottom of the hole, slowly rotating the drilling tool, supplementing high-quality slurry, carrying out reverse circulation hole cleaning, and simultaneously keeping a water head in the hole to prevent hole collapse;
when the steel pipe pile implantation process is carried out, drilling and cleaning holes in a steel pile casing to a designed elevation, stopping in time to remove a drill rod after the final hole acceptance is finished, moving a drilling machine away, placing a main hanging ship and an auxiliary hanging ship in place, hoisting and erecting the steel pipe pile from a pile transportation barge in a mode that the main hanging ship and the auxiliary hanging ship are matched for hoisting, connecting the main hanging ship with a main lifting lug at the upper part of the steel pipe pile, connecting the auxiliary hanging ship with a turnover lifting lug at the lower part of the steel pipe pile, placing the steel pipe pile into the steel pile casing through the main hanging ship, positioning the steel pipe pile 100 to the pile center position of the steel pile casing 300, tightly holding the steel pipe pile by a jack on a lower platform, confirming that the center deviation of the steel pipe pile is within an error, slowly lowering the steel pipe pile by using the main hanging ship after the verticality of the steel pipe pile meets the requirement, stopping sinking of the steel pipe pile, sleeving a hydraulic pile hammer on the top of the steel pipe pile, and, the hydraulic pile hammer slowly hammers the pile top tool flange with small energy, the pile top tool flange is of an L-shaped cross section structure, and is tightly attached and connected with the pile top flange through a connecting bolt, so that the hydraulic pile hammer hammers the pile top tool flange to protect the pile top flange from being damaged during hammering; the striking energy of the hydraulic pile hammer is increased from small to large until the steel pipe pile reaches the designed bottom elevation; closely paying attention to the perpendicularity of the pile body in the pile sinking process, and ensuring that the perpendicularity of the steel pipe pile is within 3 per mill (see figure 3);
when the bottom sealing concrete pouring process is carried out, the height of the bottom sealing is 1.5m, C40 underwater undispersed concrete is adopted, and a vertical guide pipe method is adopted for carrying out three-point pouring, wherein the three-point pouring comprises the steps of guide pipe installation, secondary hole cleaning, underwater concrete pouring and secondary pouring;
in the guide pipe installation step, an operation platform is firstly erected at the top of the steel pipe pile, and three guide pipes 30 with the inner diameter of 300mm, and a grouting inner hopper 31 and an outer hopper 32 (see fig. 4 and 5) which are sequentially connected with the tops of the three guide pipes 30 are installed on the operation platform; the three guide pipes 30 are arranged in the pile hole in an equilateral triangle manner by connecting the centers of the three guide pipes, the side length of each equilateral triangle is equal to the flowing radius of the concrete by 2.5-4.0 m, and the distance from the bottom end of each guide pipe 30 to the bottom of the pile hole is 30-50 cm;
when the secondary hole cleaning step is carried out, firstly, the air pipe is put into the guide pipe, the upper part of the air pipe is connected with an air pipe of the air compressor through a special joint, and the special joint is connected with the guide pipe; lifting the guide pipe to a certain height, wherein the height is determined according to the deposition thickness of the bottom of the pile hole, then starting an air compressor to supply air, slowly lowering the guide pipe while circulating after the air lift reverse circulation is normal until the guide pipe is lowered to the bottom of the pile hole, and removing sediment at the bottom of the pile hole when the sand content in the discharged slurry meets the requirement;
when the underwater concrete pouring step is carried out, the concrete is mixed on site and then is pumped into the guide pipe, and pouring is carried out from the bottom of the hole upwards;
and in the secondary driving step, the steel pipe pile is driven to the designed elevation by adopting a vibration hammer before the initial setting of the concrete.
When the pile outer wall backfill grouting process is carried out, grouting is carried out between the outer wall of the bottom of the steel pipe pile 100 and rock soil (see figure 6); four sets of grouting systems are arranged, and each set of grouting system comprises four grouting pipes and four slurry return pipes; when grouting, firstly grouting a grouting system at the end part of the pile, plugging the grout return pipe when the grout return pipe is discharged, continuing grouting the grouting pipe until the rated grouting pressure is reached, and stopping grouting and plugging a grouting port when the grouting flow is less than 2L/min and is maintained for 0.5h under the rated grouting pressure or when the grouting flow is increased and the grouting pressure is suddenly reduced in the grouting process.
The construction process of the implanted rock-socketed pile of the offshore wind power foundation adopts the pile stabilizing platform for auxiliary positioning, adopts the steel casing for rock-socketed construction, adopts the main crane ship and the auxiliary crane ship to be matched to lift and insert the steel pipe pile into the steel casing, can efficiently finish pile sinking construction, is also provided with the appropriate hammering equipment and drilling equipment, monitors and adjusts the posture of the steel pipe pile in the whole course to ensure that the single pile is smoothly and vertically driven into a seabed rock layer, simultaneously adopts targeted measures to keep the hole wall stable, prevents abnormal conditions such as drill jamming, drill burying and the like, ensures the bearing capacity and the stability of a pile body of the non-rock-socketed single pile, effectively improves the construction efficiency, effectively improves the horizontal resistance and the anti-pulling capacity of the rock-socketed pile, and meets the requirements of engineering structure design and construction.
The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.