CN113174992B

CN113174992B - Comprehensive treatment and reinforcement method for collapse of stratum around marine deep-water inclined pile

Info

Publication number: CN113174992B
Application number: CN202110475861.5A
Authority: CN
Inventors: 罗承浩; 郭琼玲; 孔秋平; 许万强; 许万洪; 罗发锟; 郑添寿; 张强; 邱维衍
Original assignee: Fujian Yongqiang Soil Co ltd
Current assignee: Fujian Yongqiang Soil Co ltd
Priority date: 2021-04-29
Filing date: 2021-04-29
Publication date: 2022-08-30
Anticipated expiration: 2041-04-29
Also published as: CN113174992A

Abstract

The invention discloses a comprehensive treatment and reinforcement method for collapse of the surrounding stratum of a marine deep-water inclined pile, which adopts various means such as inclined hole grouting, inclined hole jet grouting, pile stirring and the like to form an integrated new composite foundation to reinforce the soil body around the pile, has obvious effect and quality on the collapse treatment of the surrounding stratum of the marine deep-water inclined pile, effectively ensures the safe and smooth operation of subsequent pile foundation construction, greatly reduces the construction period and economic loss, effectively ensures the bearing capacity and stability of the foundation of the marine deep-water inclined pile, and avoids the occurrence of potential safety hazards.

Description

Comprehensive treatment and reinforcement method for collapse of stratum around marine deep-water inclined pile

Technical Field

The invention relates to the technical field of engineering construction, in particular to a comprehensive treatment and reinforcement method for stratum collapse around an offshore deep-water inclined pile.

Background

Pile cap foundation is a form of foundation structure, and is a deep foundation consisting of piles and pile caps (called caps for short) connecting pile tops, called pile foundations for short. If the pile body is completely buried in the soil and the bottom surface of the bearing platform is contacted with the soil body, the pile body is called a low pile bearing platform foundation; if the upper part of the pile body is exposed out of the ground and the bottom of the bearing platform is above the ground, the pile body is called a high pile bearing platform foundation. The high pile cap foundation is widely applied to offshore wind power, large-span bridges, wharfs and offshore oil platforms.

The offshore wind power pile foundation mostly adopts a high-performance marine concrete bearing platform and a steel pipe pile foundation. The steel pipe pile mainly comprises a steel pile casing and a concrete pile positioned in the steel pile casing, and is widely applied due to the advantages of enough bearing capacity, relatively simple pile sinking process, small soil discharge amount, good bending resistance and the like. With the rapid construction of offshore wind power plants, the requirements for the stability of offshore wind power pile foundations are continuously improved. Due to the severe offshore operation environment, the complexity of submarine topography and terrane, the influence of construction process and management factors easily causes the phenomenon that surrounding strata are softened, loosened and collapsed in the deepwater pile foundation construction process to cause sand leakage in the pile, the subsequent construction progress of a pile foundation is seriously hindered, the subsequent construction safety of the pile foundation is also influenced, meanwhile, the bearing capacity of the pile foundation is greatly reduced, the normal safe operation of the whole offshore wind farm is endangered, and the brought risk loss is huge.

At present, the domestic sunk foundation treatment technology is very few in research and application aiming at ocean engineering, mature and feasible technical experience references are lacked, especially, the offshore wind power deep water inclined pile foundation sunk stratum treatment technology is seriously insufficient in experience, few previous application cases only adopt single treatment measures such as drilling and grouting of traditional straight piles and the like, the effect is poor, the problem of ocean stratum sinking cannot be effectively solved, and the safety of follow-up pile foundation construction and wind power plant operation is seriously influenced.

Disclosure of Invention

The invention aims to overcome the defects that the existing marine deep water inclined pile surrounding stratum collapse treatment effect is poor and the subsequent construction and safety requirements cannot be met, and provides a comprehensive treatment and reinforcement method for marine deep water inclined pile surrounding soil collapse.

In order to achieve the above purpose of the invention, the following technical scheme is adopted:

a deep sea inclined pile surrounding stratum collapse reinforcing structure is characterized in that an original pile foundation is used as a circle center, surrounding design arrangement is adopted, inclined hole grouting and high-pressure jet grouting inclined piles are conducted in piles and on pile sides, and pile surrounding soil is reinforced in a mode that inclined hole grouting and jet grouting piles are overlapped on the outer side of a steel pipe inclined pile foundation. Meanwhile, in the area where the periphery of the outer part of the pile is collapsed, the stirring straight pile is arranged for reinforcement and is meshed with the jet grouting pile, so that a new composite foundation integrating grouting, jet grouting and stirring straight piles is formed for reinforcing the soil body around the pile, and the safety and the stability of the offshore deep-water inclined pile foundation are effectively enhanced.

A comprehensive treatment and reinforcement method for collapse of stratum around a marine deep-water inclined pile comprises the following steps:

(1) preparation work before treatment: and (3) carrying out geological exploration in the distribution range of the pile foundation, carrying out drilling coring probing before processing, distributing holes after determining the condition of a subsidence area, and measuring, setting and positioning the positions of the drilled holes on the existing pile clamping steel frame platform or the temporary erection construction platform by adopting a measuring instrument.

(2) Grouting in the pile, sealing the inclined pile end of the steel pipe: and (3) drilling a guide hole in the pile by arranging a guide device in the pile in the direction of the inclined steel pipe pile in the pile, guiding a grouting hole in the pile, and then putting the grouting pipe into the hole to perform pile end pile bottom grouting.

(3) Pile side high pressure jet grouting: and a guide sleeve is arranged on the outer side of the pile and parallel to the direction of the steel pipe inclined pile, a guide hole is drilled, and rotary spraying holes are arranged on the periphery of the steel pipe inclined pile and parallel to the direction of the steel pipe inclined pile for high-pressure rotary spraying grouting.

(4) And (3) construction of the external stirring vertical pile: and after the high-pressure rotary injection of the grout on the pile side is finished, arranging a stirring straight pile in the subsidence area on the periphery of the pile foundation to reinforce the stratum which is more peripherally subsided and separated from the pile under water.

Further, the jet grouting piles are distributed in a cross overlapping mode in the step (3) to form jet grouting pile group reinforced foundations.

Further, after the reinforcement treatment in the steps (2) to (4), the external grouting reinforcement in the step (5) is carried out: and arranging a guide sleeve in the direction of the parallel steel pipe inclined pile outside the pile, guiding a grouting hole outside the pile, then injecting cement paste by adopting a perforated pipe multiple grouting process fracture injection, and supplementing and reinforcing smaller gaps and unfilled compact parts in soil around the pile to enable the pile and soil outside the pile to be consolidated into a whole.

Further, the pile outer grouting holes in the step (5) and the rotary spraying holes in the step (3) are arranged in a staggered mode.

Further, a pile cap is installed on the top of the pile before grouting in the pile in the step (1), so that grouting in the pile is more compact and solidified.

And (2) further, arranging a guiding and positioning device in the pile in the step (1) to ensure that the inclination of the grouting pipe in the pile is kept parallel to the inclined pile of the steel pipe.

Further, the pile side guide sleeve in the step (3) and the step (5) is fixed by a hoop.

Further, the rotary spraying pressure of the rotary spraying grouting in the step (3) is 10-20 Mpa, and the water-cement ratio is 1.2: 1.0-0.8: 1.0.

Further, the inclined hole grouting in the pile and outside the pile, the pile side jet grouting pile, the pile outer stirring straight pile, the steel pipe inclined pile and the soil body around the pile are combined and crosslinked into an integral composite foundation reinforcing structure.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. the invention provides a comprehensive treatment and reinforcement method for stratum collapse around an offshore deep-water inclined pile foundation, which is used for reinforcing and reinforcing the collapsed stratum around the inclined pile foundation before pile forming in an offshore deep-water environment, effectively ensuring the subsequent safe and smooth construction of the pile foundation, reinforcing the collapsed area of the inclined pile foundation after pile forming, and effectively enhancing the bearing capacity and stability of the inclined pile foundation.

2. The method of the invention is adopted for reinforcement treatment, a new composite foundation which integrates grouting, jet grouting pile and stirring straight pile is formed, the cracks of soil around the steel pipe inclined pile are filled, the connection degree of the steel pipe inclined pile and the soil layer around the pile is strengthened, the outer side of the pile and the surrounding soil body are effectively and tightly consolidated into a whole, the friction force of the soil around the pile is greatly improved, and the stability of the offshore deepwater inclined pile foundation is enhanced. Greatly reducing the follow-up construction period and the economic loss of engineering, and effectively avoiding the occurrence of the potential safety hazard in the later operation.

Drawings

FIG. 1 is a schematic diagram illustrating the situation of stratum collapse around a deep-sea inclined pile in the embodiment;

FIG. 2 is a design diagram of a treatment and reinforcement scheme for the collapse of the stratum around the offshore deep water inclined pile;

FIG. 3 is a construction step diagram of a treatment and reinforcement scheme for the collapse of the stratum around the offshore deep water inclined pile;

FIG. 4 is a schematic diagram illustrating the effect of reinforcement treatment according to an embodiment of the present invention;

FIG. 5 is a schematic view of a grouting perforated pipe for pile side grouting.

Reference numerals: 1. steel pipe inclined piles; 21. grouting holes in the piles; 22. grouting holes outside the piles; 23. spirally spraying holes; 210. grouting inclined holes in the piles; 220. grouting an outer inclined hole of the pile; 230. carrying out jet grouting pile; 240. stirring the vertical piles; 30. a guide sleeve; 31. a connecting member; 32. hooping; 33. a guiding and positioning device in the pile; 40. grouting a floral tube; 41. flower holes; 42. pile end face; 11. a medium-coarse sand layer; 12. completely weathered granite; 13. sandy strongly weathered granite; 14. cracked strongly weathered granite; 15. apoplexy granite; 16. a collapsed region; 17. c40 micro-expansive concrete; 100. temporarily clamping a pile steel platform; 101. averaging the sea level; 102. average surface of the sea bed.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

The foundation form to be adopted by the offshore wind farm in a certain place is a high pile cap foundation (including a driving friction pile foundation, a drilling friction pile foundation and a rock-socketed pile foundation). The service life of the basic design is twenty-five years. High pile cap foundations typically contain 6-8 batter piles.

According to the geological survey data, the submarine stratum structure of the offshore wind farm of a certain place comprises a silt layer, silt-containing fine sand, silty clay, a medium-coarse sand layer 11, fully weathered granite 12, sandy strongly weathered granite 13, fractured strongly weathered granite 14, and weathered granite 15 and the like within the drilling depth control range.

During pile forming, in the process of sinking the steel pipe inclined pile 1 by using a high-frequency vibration hammer, water is added due to vibration, so that a plurality of steel pipes and surrounding soil layers are loosened and sink downwards, and then soil around the pile is poured into the pile from the outside of the pile to form a funnel-shaped sinking area of the soil around the pile from the bottom to the top.

Fig. 1 is a schematic diagram showing the situation of soil collapse around the foundation of one steel pipe inclined pile 1, wherein a pile foundation is not formed at one position, the water depth at the pile position is about 15m, and during pile forming, due to severe collapse, about 300 cubes of dry mixed concrete are cast and filled in the position of the positive surface of the south side of the pile, and the collapse leakage point can not be blocked. The underwater model finds that the collapse area 16 around the pile is large, and an obvious collapse area with the diameter of 6m and the depth of more than 4m is arranged on the south side of the pile; the drilling finds out that a plurality of holes exist in the depth range of 4-12 meters below the mud surface around the pile, an obvious water leakage channel is arranged on the south side of the pile and reaches the bottom of the steel pipe inclined pile, the shape of the funnel is formed, the depth is 16.50 meters below the sea bottom, and a large amount of sacked rags exist around the water leakage channel. The steel pipe inclined pile 1 can be constructed continuously only by reinforcement.

The collapse point can not be blocked after the collapse area 16 is subjected to hole leading grouting outside the pile in a traditional straight hole mode, and effective reinforcement can not be carried out. And the adoption of the straight hole can not ensure that the soil body around the inclined pile foundation is fully reinforced, and blank areas which can not be reinforced and covered exist.

In the embodiment, a reinforcing structure for stratum collapse around a marine deep-water inclined pile is adopted, a steel pipe inclined pile 1 is used as a center, annular arrangement is adopted, inclined holes are formed in the pile and on the pile side, the inclined holes comprise pile inner inclined hole grouting 210, pile side high-pressure jet grouting pile 230 and pile outer inclined hole grouting 220, and pile periphery soil is reinforced by overlapping the pile inner inclined hole grouting and pile outer inclined hole jet grouting pile 230 around the steel pipe inclined pile 1 base. Meanwhile, the stirring straight piles 240 are arranged outside the piles, the stirring straight piles 240 are meshed with each other, and reinforcing treatment is carried out on the peripheral collapse area 16, so that slurry is combined with soil bodies around the piles through the functions of infiltration, filling, compaction, splitting and the like, a new composite foundation formed by crosslinking grouting, the jet grouting piles 230 and the stirring straight piles 240 into a whole is formed to reinforce the soil bodies around the piles, and the stability of the wind turbine foundation is enhanced.

In the embodiment, qualified P.O.42.5 cement with high corrosion resistance is used, a witness sampling test is carried out before the cement is used, the cement can be used after the cement is qualified by the test, and the deteriorated or hardened cement is strictly forbidden to be used. During construction, cement slurry is adopted, and the water-cement ratio is 0.8: 1-1: 1. In order to avoid precipitation and pipe blockage, construction is carried out by adopting dilution first and then concentration, and upper dilution and lower concentration.

The comprehensive treatment and reinforcement method for the collapse of the offshore deep water inclined pile foundation in the embodiment comprises the following steps:

(1) early exploration probing: the geology within the pile foundation distribution range is explored, the pre-processing drilling coring probing pattern is processed, and the specific conditions of the subsidence area 16 are determined.

(2) Pre-estimating the engineering quantity of a single pile: according to the existing engineering experience, the diameter of the high-pressure jet grouting pile 230 is 1500mm, the reinforcing diameter of the cement stirring straight pile 240 is 600mm, and the grouting diffusion radius is 1.0 m. It is planned to arrange 4 in-pile grouting holes 21 in the pile, 8 or more out-pile grouting holes 22, 8 or more high-pressure rotary jet holes 23, and 20 or more cement-mixed straight piles 240 outside the pile, as shown in table 1. The mixing vertical pile 240 reinforces the stratum of the subsidence area 16, the rotary spraying pile 230 and the grouting are carried out to overlap and reinforce the soil around the pile around the steel pipe inclined pile 1, so that no blank unreinforced area is ensured, and the soil around the pile is fully treated.

In this embodiment, the number of the grouting holes, the jet grouting piles 230 and the stirring straight piles 240 is related to the range of the single-pile collapse area 16, and the grouting holes need to be encrypted if a gap is too large during construction, so that no blank unreinforced area is ensured, and the purpose of forming an integral composite pile foundation with the soil around the steel pipe inclined pile 1 is achieved.

TABLE 1 Single pile engineering quantities for this example

(3) Manufacturing and installing a temporary pile clamping steel platform 100: the existing pile clamping platform can be utilized for treating the soil around the pile which is not formed into the pile, and a temporary construction platform of a steel truss is erected at the lowest tide water level below the bearing platform for treating the soil around the formed pile.

(4) Hole distribution: drawing the arrangement diagram of the grouting holes, the jet grouting holes 23 and the stirring vertical pile holes, as shown in figure 2. 4 in-pile grouting holes 21 are arranged in the steel pipe inclined pile 1, 8 rotary spraying holes 23 and 8 out-pile grouting holes 22 are arranged around the steel pipe inclined pile 1 in a circle, and about 20 stirring straight piles 240 are arranged in the collapse area 16 and are numbered uniformly.

(5) Positioning and paying off: and (3) performing coordinate positioning on the steel pipe inclined pile 1 according to a pile foundation design drawing and the condition of the explored collapse area 16 and according to the position of the bottom edge line of the foundation pit, the site elevation and the inclination of the steel pipe inclined pile 1. And (3) setting the drilling position by adopting a measuring instrument to measure and set the line on the existing temporary pile clamping steel platform 100 or a temporary building construction platform according to the design requirement, and if the gap is too large, sealing the grouting hole until the grouting can be ensured to be filled.

(6) Grouting 210 an inclined hole in the pile, sealing the inclined pile end of the steel pipe: and (3) guiding holes to drill in the direction of the parallel steel pipe inclined pile 1 in the pile through arranging a pile inner guiding and positioning device 33, guiding a pile inner grouting hole 21, then putting a grouting pipe into the hole, and grouting the pile bottom at the pile end.

4 in-pile grouting holes 21 parallel to the direction of the pile body are led in the pile, in order to avoid the leading holes from touching and damaging the inner wall of the steel pipe inclined pile 1, the drilling holes are arranged to be 0.3-0.5 m inside the pile wall, the in-pile grouting holes 21 are symmetrically distributed, and the aperture is 110 mm. The deviation between the drilling position and the design position is not more than 10cm, and the inclination of the grouting hole 21 in the pile is not 1% deviation. And accurately recording the drilling depth, and comparing the drilling depth with a pile sinking record report. And (3) preparing cement paste with a water-cement ratio of 1:0.8, grouting the bottom of the pile at the end of the pile, and filling the interior of the pile to a certain height (more than 2.0 m). The method aims to fill the gaps around the pile and seal the pile bottom of the steel pipe inclined pile 1, so as to block the fluidity of seawater caused by tide at the pile bottom, and avoid the influence on the subsequent stirring straight pile and grouting effect caused by slurry leakage from the pile during subsequent grouting. And simultaneously, the pile inner and pile outer reinforcing structures at the pile end are combined to form an integral overlapping structure. If the gap is too large in the construction process, the number of grouting holes needs to be increased until the grouting can be ensured.

Preferably, a pile cap (not shown) is installed on the top of the pile before grouting to make the grouting 210 more compact and solidified.

Preferably, the in-pile guide positioning device 33 is installed such that the inclination of the in-pile grout pipe is maintained parallel to the steel pipe batter pile 1. Guiding orientation device 33 is wooden guide support plate in the stake in this embodiment, opens 4 stake internal grouting holes 21 in the guide support plate, and the slip casting pipe passes the hole and transfers, transfers to about 0.5m below stake end to open the drill guiding hole behind the 42 positions of stake terminal surface. The purpose of pile end pile bottom grouting is to seal the pile bottom by filling gaps around the pile, prevent the subsequent slurry from leaking from the interior of the pile during pile side grouting and simultaneously combine the interior of the pile at the pile end with the grouting reinforcement structure outside the pile to form an integral foundation structure.

(7) Grouting by rotary spraying at the side of the pile: and a guide sleeve 30 is arranged on the outer side of the pile in the direction parallel to the steel pipe inclined pile 1, a guide hole is drilled by using the guide sleeve 30, and rotary spray holes 23 are drilled in parallel on the periphery of the steel pipe inclined pile 1 for high-pressure rotary spray grouting.

A pile-side guide sleeve 30 is arranged in parallel outside the steel pipe inclined pile 1. The position and the inclination of the pile side guide sleeve 30 are adjusted according to the inclination of the pile foundation, so that the pile side guide sleeve 30 and the steel pipe inclined pile 1 are kept parallel.

In this embodiment, the pile-side guide sleeve 30 is fixed by means of a hoop 32. Steel pipe encircling buckles are arranged at intervals of 6m in the longitudinal direction of the steel pipe inclined pile 1, and each buckle is provided with 6 guide sleeves 30. The diameter of the installed pile side guide sleeve is 30 mm, and the distance from the center to the edge of the pipe pile is 0.4 m. The guide sleeve 30 is inclined to the steel pipe spud 1 in conformity with the inclination thereof, and the inner wall of the guide sleeve 30 must be smooth. The guide sleeve 30 is inserted into the mud surface through the sea bed surface to a certain depth and is stable, the installation of the process is difficult, and a diver needs to be matched for installation when necessary. Other mounting means, such as sliding rails, slot fixing, sleeve mounting, etc., may also be employed for the pile-side guide sleeve 30. After the grouting is completed, the pile-side guide sleeve 30 can be removed and reused. The pile side guide sleeve 30 has the effects of stabilizing and protecting the subsequent rotary spraying and grouting operation, and avoiding the construction difficulty caused by the buoyancy and scouring of seawater on the subsequent grouting; and secondly, the inclination of rotary spraying and grouting is effectively controlled to be parallel to the inclined pile, and inclined hole rotary spraying and inclined hole grouting operation is guaranteed.

The pile side guide sleeve 30 and the steel pipe inclined pile 1 are kept parallel to carry out inclined hole reinforcing treatment, and the purpose is to ensure that the soil around the foundation of the steel pipe inclined pile 1 is sufficiently reinforced without blank areas; if adopt traditional perpendicular straight hole, on the one hand need punch according to the different degree of depth layering and consolidate and increase the pilot hole work load, consume the cycle length, on the other hand can not ensure that the soil body around the steel pipe batter pile 1 is consolidated fully, has the blank that can't consolidate the cover, just also can't ensure the quality of consolidating the processing.

After the pile side guide sleeve 30 is installed, the platform is cleaned to install the drilling machine, and the inclination of the drilling machine is adjusted (the error is less than 1.0%). The method is characterized in that 8 rotary spraying holes 23 parallel to the direction of a pile body are led by utilizing a pile side guide sleeve 30, the steel pipe inclined pile 1 is symmetrically distributed by taking the steel pipe inclined pile 1 as the center, the drill holes are arranged to be 0.5-0.8 m outside the pile wall, the outer wall of the steel pipe inclined pile 1 is prevented from being damaged by the contact of the guide holes, the rotary spraying diameter is 1200-1600 mm, and the number of the rotary spraying piles 230 is enough, so that cement slurry is poured into the top, the bottom and the side part of the soil around the steel pipe inclined pile 1 within the range of 1-2 m, and no blank unreinforced area exists. And accurately recording the drilling depth, and comparing the drilling depth with a pile sinking record report. Before the construction of the drilling machine, low-pressure trial spraying is firstly carried out on the platform, and after the trial running of the drilling machine is normal, the pilot hole drilling is started. And after the pilot hole is drilled, inserting a rotary spray pipe, performing test spraying, and after the construction technical parameters are determined, putting the spray pipe to the bottom of the hole. In order to improve the quality of the bottom end of the pile, the drilling rod guniting rotary spraying time is properly increased within 1.0m of the bottom of the pile. After the injection grouting pipe is inserted into the designed depth, the high-pressure slurry pump pressurizes to 15-20 MPa, and then performs rotary spraying from bottom to top, and simultaneously cleans and discharges slurry. In the rotary spraying lifting process, the rotary spraying parameters are continuously adjusted according to different positions. Finally forming the jet grouting pile 230.

Preferably, an inner sleeve follow-up treatment is used during the hole leading process to avoid the influence of hole re-collapse.

In this embodiment, the deviation between the drilling position and the design position is not preferably larger than 10 cm. The aperture of the high-pressure rotary jet hole 23 is 110mm, the hole inclination is less than or equal to 1 percent, and the hole depth is not less than 1m below the pile end of the steel pipe inclined pile 1. The water-cement ratio is 1.2: 1.0-0.8: 1.0, and the rotary spraying pressure is 10-20 Mpa. And in the rotary spraying lifting process, the rotary spraying parameters are continuously adjusted according to different positions.

TABLE 2 technical parameter table of high-pressure jet grouting construction process of the embodiment

(8) And (3) construction of the external stirring vertical pile: after the pile side jet grouting is finished, arranging the stirring straight pile 240 in the collapse area 16 on the periphery of the pile foundation, and reinforcing the collapse area on the periphery of the underwater pile. The plurality of stirring straight piles 240 are meshed with each other, the stirring straight piles 240 are mutually cross-linked with the jet grouting piles 230 on the pile side, the soil area around the pile is completely covered, no unreinforced blank area exists, and an integral new composite foundation is formed to reinforce the soil around the pile.

Cleaning the platform and installing the drilling machine, and adjusting the inclination of the drilling machine (the error is less than 1.0%). And after the drilling machine is normally operated, stirring drilling is started, and the drilling depth is recorded in detail in the drilling process. And (3) carrying out underwater stratum strengthening treatment on the stirring straight pile 240 in the peripheral collapse area 16 of the pile foundation.

In this embodiment, the collapse area 16 at the periphery of the steel pipe inclined pile 1 is treated by more than 20 stirring vertical piles 240. The diameter of the stirring vertical pile 240 is 600mm, and the hole depth is not less than 0.1m on the bottom of the pile. The water-cement ratio is 1.1: 1.0-0.8: 1.0, and the pressure of the stirring paddle is 0.1-0.2 Mpa.

Table 3 technical parameter table of construction process of external stirring vertical pile of this embodiment

(9) Checking the gap and touching the weak position.

(10) Grouting outside the pile for reinforcement: the guide sleeve 30 is arranged in the direction of the parallel steel pipe inclined pile 1 on the outer side of the pile, after the inclined hole is led out of the pile, namely the pile outer grouting hole 22, grouting perforated pipes 40 are adopted for multiple times of grouting process to split and inject cement paste, and small gaps and unfilled compact positions in soil around the pile are supplemented and reinforced, so that the pile and soil outside the pile are consolidated into a whole, and the reinforcement is ensured to be sufficient.

In the embodiment, inclined holes are drilled for grouting reinforcement, and single cement slurry is poured by adopting a grouting process of a grouting perforated pipe 40 after drilling. Cleaning a platform, installing a drilling machine in the middle of 2 rotary spraying holes 23, adjusting the inclination of the drilling machine (the error is less than 1.0 percent), and leading 8 pile outer grouting holes 22 parallel to the direction of a pile body. And (3) debugging a stirrer and a slurry pump before drilling to ensure that the equipment runs normally. And (3) drilling by using an XY-300 type drilling machine, and drilling by using a mud wall protection method, wherein the hole diameter of the drilled hole is 110 mm. The number of drill rod sections is well recorded in the drilling process, and the accuracy of the drilling depth is ensured. And the position of the void is recorded. FIG. 5 is a schematic view of a pile side grouting lower grouting pipe according to the present invention. When drilling to the treatment depth range, the speed is slowed down, and the drilling conditions are carefully observed, such as the existence of slurry leakage, the existence of filling materials (necessary coring), and the like. Grouting floral tube 40 installation principle: and all grouting pipes 40 (the caliber is 50mm) are arranged at the deeper section, the bottoms and the positions of holes of the grouting pipes 40 are arranged, and the pipe openings are about 30cm higher than the pile clamping platform. In the embodiment, the external grouting reinforcement of the pile adopts multiple times of pressurization splitting grouting, and the hole forming cleaning is required before grouting, so that the condition that the cleaning solution becomes clear is met.

(11) Moving to the next construction pile position and repeating the steps. And 7-14 days after grouting, carrying out spot check according to the number of pile holes, and carrying out a compression test and a standard penetration test. Through detection, the soil around the pile is compactly and stably filled, does not leak water, and has better reinforcing effect.

In the steps (6) - (7) and (10), inclined hole drilling is a key process for constructing a prerequisite foundation for subsequent reinforcement measures and ensuring that the stratum around the pile is sufficiently collapsed and reinforced. The invention comprehensively treats and reinforces the collapse area of the offshore deep water inclined pile foundation by various means through the construction steps, solves the problem of pile foundation collapse caused by soil body loosening and loss due to construction vibration, forms an integral new composite foundation on the soil body around the pile, has obvious treatment effect on the collapse of the offshore deep water inclined pile foundation, and enables the subsequent construction of the offshore wind power plant pile foundation to be smoothly carried out. Compared with the traditional straight hole treatment mode, the construction cost is low, and the period is short.

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the embodiments disclosed, but should include various alternatives and modifications without departing from the present invention, which are encompassed by the appended claims.

Claims

1. A comprehensive treatment and reinforcement method for surrounding stratum collapse of offshore deep water inclined pile, wherein the inclined pile is a steel pipe inclined pile foundation, and is characterized by comprising the following steps:

(1) preparation work before treatment: performing geological exploration in a pile foundation distribution range, processing a pre-drilling coring probing pattern, determining the condition of a subsidence area, then distributing holes, and measuring and setting a paying-off positioning hole outlet position on an existing pile clamping steel frame platform or a temporary erection construction platform by adopting a measuring instrument;

(2) grouting in the pile, sealing the inclined pile end of the steel pipe: drilling a guide hole in the pile by arranging a guide device in the pile in the direction parallel to the inclined steel pipe pile in the pile, guiding a grouting hole in the pile, then lowering a grouting pipe into the hole, and grouting the pile bottom at the pile end;

(3) pile side high pressure jet grouting: arranging a guide sleeve outside the pile in a direction parallel to the steel pipe inclined pile, drilling a guide hole, arranging rotary spraying holes on the periphery of the steel pipe inclined pile in a direction parallel to the steel pipe inclined pile, and performing high-pressure rotary spraying grouting;

2. The comprehensive treatment and reinforcement method for the collapse of the stratum around the offshore deep water inclined pile according to claim 1, characterized by comprising the following steps: and (4) in the step (3), the rotary spraying piles are distributed in a crossed and overlapped mode to form a rotary spraying pile group reinforced foundation.

3. The comprehensive treatment and reinforcement method for stratum collapse around the offshore deep water inclined pile according to claim 1, characterized by comprising the following steps: and (3) performing grouting reinforcement outside the pile in the step (5) after reinforcement treatment in the step (2) and the step (4): and arranging a guide sleeve in the direction of the parallel steel pipe inclined pile outside the pile, guiding a grouting hole outside the pile, then injecting cement paste by adopting a perforated pipe multiple grouting process fracture injection, and supplementing and reinforcing smaller gaps and unfilled compact parts in soil around the pile to enable the pile and soil outside the pile to be consolidated into a whole.

4. The comprehensive treatment and reinforcement method for stratum collapse around offshore deep water inclined pile according to claim 3, characterized by comprising the following steps: and (5) arranging the pile outer grouting holes and the rotary spraying holes in the step (3) in a staggered mode.

5. The comprehensive treatment and reinforcement method for stratum collapse around the offshore deep water inclined pile according to claim 1, characterized by comprising the following steps: and (3) installing a pile cap sealing steel pipe inclined pile on the pile top before grouting in the pile in the step (1), so that grouting in the pile is more compact and solidified.

6. The comprehensive treatment and reinforcement method for stratum collapse around the offshore deep water inclined pile according to claim 1, characterized by comprising the following steps: and (3) arranging a guiding and positioning device in the pile in the step (1) to ensure that the inclination of the grouting pipe in the pile is kept parallel to the inclined pile.

7. The comprehensive treatment and reinforcement method for the collapse of the stratum around the offshore deep-water inclined pile according to claim 3, characterized by comprising the following steps: and (5) fixing the pile side guide sleeve by adopting a hoop.

8. The comprehensive treatment and reinforcement method for stratum collapse around offshore deep water inclined pile according to claim 1 or 2, characterized by comprising the following steps: and (3) carrying out rotary spraying grouting at a rotary spraying pressure of 10-20 Mpa and a water-cement ratio of 1.2: 1.0-0.8: 1.0.

9. The comprehensive treatment and reinforcement method for stratum collapse around offshore deep water inclined pile according to claim 3, characterized by comprising the following steps: and (3) grouting inclined holes in and outside the piles, spirally spraying piles on the sides of the piles, combining the vertical piles with the inclined steel pipe piles and soil around the piles outside the piles, and crosslinking to form an integral composite foundation reinforcing structure.