CN117107836A - Method and system for reinforcing foundation of existing structure in limited space - Google Patents

Abstract

The application relates to the technical field of foundation reinforcement, in particular to a method and a system for reinforcing a foundation of an existing structure in a limited space. The reinforcing method comprises the following steps: forming pile pressing holes by perforating the raft, and hanging pile barrels into the pile pressing holes, wherein the pile barrels are barrels with openings at two ends; pressing the pile barrels into the foundation below the raft from the pile pressing holes section by section to a preset depth; digging out the soil plug in the pile cylinder and transporting out of the pile cylinder, and expanding the bottom of the pile end to ensure that the aperture of the bottom of the pile cylinder is larger than that of the pile cylinder; pouring core filling concrete into the pile cylinder and the reaming at the bottom of the pile cylinder, recovering the raft and sealing the holes. The application adopts the construction sequence of firstly static pressure steel pile casing and then manually excavating the soil plug in the steel pile casing, so that the pile body can smoothly reach the designed depth, and the application can work in a limited space and has high construction speed. Meanwhile, the construction method of expanding the bottom at the pile end can enable the pile body and the soil body to be combined more tightly.

Description

Method and system for reinforcing foundation of existing structure in limited space

Technical Field

The application relates to the technical field of foundation reinforcement, in particular to a method and a system for reinforcing a foundation of an existing structure in a limited space.

Background

The disclosure of this background section is only intended to increase the understanding of the general background of the application and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.

Due to the influence of external environmental factors, investigation, design and construction errors, building function changes and other factors, the bearing capacity of the existing or newly built structure does not meet the requirement, or the foundation is excessively settled or inclined. In order to ensure the normal use and safety of the structure, it is necessary to reinforce the foundation of such a structure.

For high-rise or super high-rise buildings, especially the existing building engineering, the foundation is large in burial depth, the construction is needed in a basement, the operation surface is small, the construction process is greatly limited, the conventional construction machinery cannot construct indoors, and the optimal method is the anchor rod static pressure pile construction process.

The conventional static pressure pile foundation reinforcement at present usually adopts precast concrete short piles, along with the increase of pile pressing depth, pile pressing force is required to be continuously increased, pile pressing counter force provided by an upper structure is limited, and measures such as hole guiding are required to be adopted when a hard soil layer is encountered. And the pile body has the problems of lower integrity, unstable bearing and the like.

Disclosure of Invention

Aiming at the defects existing in the prior art, the embodiment of the application aims to provide a method for reinforcing the foundation of the existing structure in the limited space, wherein the construction sequence of firstly static pressure steel pile casings and then manually excavating soil plugs in the steel pile casings is adopted, so that the pile body can smoothly reach the design depth, the pile body can work in the limited space, and the construction speed is high. Meanwhile, the construction method of expanding the bottom at the pile end can enable the pile body and the soil body to be combined more tightly.

In order to achieve the above object, the embodiment of the present application provides the following technical solutions:

a method for reinforcing the foundation of the existing structure in a limited space comprises the following steps:

forming pile pressing holes by perforating the raft, and hanging pile barrels into the pile pressing holes, wherein the pile barrels are barrels with openings at two ends;

pressing the pile barrels into the foundation below the raft from the pile pressing holes section by section to a preset depth;

digging out the soil plug in the pile cylinder and transporting out of the pile cylinder, and expanding the bottom of the pile end to ensure that the aperture of the bottom of the pile cylinder is larger than that of the pile cylinder;

pouring core filling concrete into the pile cylinder and the reaming at the bottom of the pile cylinder, recovering the raft and sealing the holes.

Optionally, the raft opening includes: determining the position and the aperture of the opening, and mechanically drilling the raft foundation within a preset range of the center of the opening, wherein the preset range is smaller than the aperture of the opening, manually removing concrete of the raft foundation within the remaining range of the opening, exposing a reinforcing mesh of the existing raft foundation, and cutting off to form a pile pressing hole.

Optionally, installing the hydrostatic apparatus body structure after forming the pile pressing hole includes: hanging a pile cylinder into the pile pressing hole, propping against a soil layer to be excavated below the pile cylinder, and sequentially installing a steel backing plate, a jack and a counterforce frame above the pile cylinder; and after the pile barrels are pressed into the foundation below the raft section by section from the pile pressing holes to a preset depth, the steel backing plate, the jack and the reaction frame are disassembled.

Optionally, after the main structure of the hydrostatic equipment is installed, steel strand anchor cables are downwards driven into the bottom of the reaction frame, the upper ends of the steel strand anchor cables are connected with the reaction frame, and the lower ends of the steel strand anchor cables are connected with the raft.

Optionally, the pile casing is pressed into the stroke mud layer.

Optionally, after the soil plug and the pile end are excavated and the bottom is enlarged, layering the reinforcement cages below the pile cylinder and connecting adjacent reinforcement cages.

Optionally, pouring core concrete into the pile cylinder and the bottom reaming of the pile cylinder comprises: after the grouting pipe is inserted into the pile bottom, sand gravel is filled into the pile, cement slurry is injected into the sand gravel pile body through the grouting pipe, and concrete is vibrated by a vibrating rod.

Optionally, pouring micro-expansive concrete after recovering the raft, and sprinkling water for curing after final setting of the micro-expansive concrete.

The embodiment of the application also provides a reinforcing system for the reinforcing method of the foundation of the existing structure in the limited space, which comprises the following steps: pile cylinder, jack, counterforce frame, steel backing plate, steel strand anchor cable, steel reinforcement cage and connecting assembly; pile cylinder is installed in the stake hole of raft, steel backing plate sets up pile cylinder upside, the jack sets up steel backing plate upside, the reaction frame sets up the jack upside, steel strand wires anchor rope upper end is connected the reaction frame, the lower extreme is connected the raft, the steel reinforcement cage below is arrived inside the pile cylinder, coupling assembling connects two adjacent steel reinforcement cages.

Optionally, the two adjacent reinforcement cages are respectively provided with a first reinforcement and a second reinforcement, the end parts of the first reinforcement and the second reinforcement are provided with threads, and the threads of the first reinforcement and the second reinforcement are opposite in rotation direction; the connecting assembly comprises a first sleeve, a second sleeve, a first lock sleeve and a second lock sleeve, wherein two ends of the first sleeve are respectively in threaded connection with the first steel bars and the second steel bars, two ends of the second sleeve are respectively in threaded connection with the first steel bars and the second steel bars, the first sleeve and the second sleeve are combined into a cylinder, the first lock sleeve is in threaded connection with the first end of the cylinder, and the second lock sleeve is in threaded connection with the second end of the cylinder.

One or more technical solutions provided in the embodiments of the present application at least have the following technical effects or advantages:

compared with the traditional variable cross-section static pressure pile and concrete static pressure pile, the application adopts the construction sequence of firstly static pressure steel pile casing and then manually excavating soil plugs in the steel pile casing, on one hand, the pile end of the manually excavated pedestal pile has no sediment, and the end resistance of the wind formation in the pile end is fully exerted, thereby achieving the aim of reinforcing the foundation; on the other hand, the manual hole digging pile can be constructed in a limited space without noise pollution, civilized construction is carried out, the pile body quality is easy to be ensured, and the pile body can smoothly reach the design depth.

Additional aspects of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of the main structure of a steel casing hole-digging bottom-expanding static pressure pile according to an embodiment of the application;

FIG. 2 is a schematic view of pile end bottom expansion according to an embodiment of the present application;

FIG. 3 is a schematic view of a split straight threaded sleeve according to an embodiment of the present application;

fig. 4 is a schematic view of a reinforcement cage connection according to an embodiment of the present application;

FIG. 5 is a schematic view of a steel casing connection groove according to an embodiment of the present application;

FIG. 6 is a diagram of raft recovery according to an embodiment of the present application;

FIG. 7 is a schematic view of the pile body after grouting is completed according to the embodiment of the application;

in the figure: 1. a steel pile casing; 2. a raft; 3. filling core concrete; 4. micro-expansive concrete; 5. a jack; 6. an oil pump; 7. a frame beam; 8. a reaction frame; 9. split straight thread sleeve; 10. grouting pipe; 11. a steel backing plate; 12. round table shaped holes; 13. steel strand anchor cable; 14. a pressure gauge; 15. groove; 16. expanding the bottom of the pile end; 17. a reinforcement cage; 18. a water stop; 19. raft steel bars; 20. a lock sleeve; 21. a semicircular sleeve;

the mutual spacing or dimensions are exaggerated for the purpose of showing the positions of the various parts, and the schematic illustrations are used for illustration only.

Detailed Description

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Furthermore, it will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components, and/or groups thereof.

The static pressure pile construction process is a foundation reinforcing technology widely applied to the foundation of the existing building, and uses dead weight load exerted by the building as pile counterforce by embedding anchor rods on the foundation, and uses a jack to press the sectional steel pile casing into the soil section by section from a pile pressing hole reserved or cut in the foundation, and then connects the pile body with the foundation, thereby achieving the purposes of improving the bearing capacity of the foundation and controlling sedimentation. Pile extension treatment is needed between each section of precast pile, foundation dragging and changing are carried out after the designed pile length and the designed pile pressing force are achieved, and finally a complete static pressure pile is formed under the existing building foundation, so that the foundation reinforcement effect is achieved.

The prior published Chinese patent CN202220445072.7 discloses a foundation reinforcement method by adopting variable-section steel pipe static pressure piles, and the pile pressing resistance in the construction process of the steel pipe static pressure piles is reduced by arranging a plurality of groups of variable-section steel pipe static pressure piles under a foundation, but the lower cross section of the pile bottom brings simple construction, and simultaneously, the integral bearing capacity of the pile body is improved to be lower, and particularly, the pile body is easy to damage due to the fact that the pressure of the whole building born by the pile bottom is larger.

The application relates to a pile end grouting miniature steel pipe static pressure pile, which is invented by Chinese patent CN202221590270.9, and solves the problem that the compactness of a pile body and surrounding soil is not high, and simultaneously adopts a mode of grouting the pile bottom by adopting a plurality of components. But the pile body has lower integrity and high operation difficulty, and the pile end is not perforated, so that the grouting work is difficult.

In order to solve the above technical problems, the present embodiment proposes a method for reinforcing a foundation of an existing structure in a limited space.

For better understanding, the reinforcement system to which the description applies first, as shown in fig. 1-7, comprises: steel pile casing 1 (i.e. pile casing), raft plate 2, core concrete 3, micro-expansion concrete 4, jack 5, oil pump 6, frame beam 7, reaction frame 8, split type straight thread sleeve 9 (i.e. connecting component), grouting pipe 10, steel backing plate 11, round table shaped hole 12 (i.e. pile hole), steel strand anchor rope 13, pressure gauge 14, groove 15, pile end expanded bottom 16, reinforcement cage 17, water stop 18, raft plate reinforcement 19, lock sleeve 20, semicircular sleeve 21.

As shown in FIG. 5, the steel pile casing 1 adopts a steel pipe with the diameter of 1000mm and the wall thickness of 11mm, each section of steel pile casing 1 is 2.0m long, and the maximum pile pressing force is 20000kN. The bearing layer is made of apoplexy mudstone, the pile end enters into the apoplexy mudstone for 4.0m, and the pile end is expanded to 1600mm.

As shown in fig. 1, the principle of static pressure operation of the steel pile casing 1 adopted in the embodiment is to use the dead weight of the built part of the building as ballast, embed steel strand anchor cables 13 to fix a reaction frame 8 on the foundation to provide reaction support, and utilize a jack 5 to press the steel pile casing 1 into the soil section by section until the pile pressing dynamic resistance or the pile pressing depth reaches the design requirement, thereby achieving the purposes of improving the bearing capacity of the foundation and controlling the sedimentation.

The reaction frame 8 used in this embodiment mainly comprises a cross beam, an upright post, and a base. As shown in fig. 1, in the use process, the upper part of the reaction frame is required to prop against the frame beam 7, the lower part of the reaction frame is fixed on the jack 5 to build the dead weight of the building as ballast, the reaction frame 8 provides reaction support, and the steel pile casing 1 is pressed into the soil section by using the jack 5 until the pile pressing dynamic resistance or the pile pressing depth reaches the design requirement.

As shown in fig. 5, the groove 15 connecting two sections of steel casings in this embodiment refers to a groove with a certain geometry formed by processing and assembling a part to be welded of a welding piece, and the groove 15 can enable a heat source (electric arc or flame) to reach the root of a welding seam so as to ensure that the joint of the two sections of steel casings 1 is firmly welded.

In this embodiment, the split type straight threaded sleeve 9 for connecting two sections of steel bars 17 is a novel rib stripping rolling straight threaded joint, as shown in fig. 3 and 4, the process principle is that two threaded heads of the steel bars to be connected are fastened by two semicircular threaded sleeves 21, the threads of the heads are tightly meshed with the threads of the semicircular sleeves 21, and the two semicircular sleeves 20 and the steel bar heads are locked by the threads through the lock sleeve 20, so that the two semicircular sleeves 20 and the steel bar heads are connected into a whole to achieve the purpose of connection. The end faces of the reinforcing steel bars are required to be flat-headed before the reinforcing steel bar cages 17 are butted, then the flat-headed end faces of the reinforcing steel bars are stripped to roll threads, one end of the reinforcing steel bar thread head of the butted part of two adjacent sections of the reinforcing steel bar cages 17 is required to be processed into right-handed threads, the other end of the reinforcing steel bar thread head is processed into left-handed threads, marks are made after the processing is finished to show distinction and facilitate the matching with split type sleeves with positive and negative screw threads, split type sleeve joints with the diameters consistent with the diameters of main bars are adopted at the parts of the sections to be butted and connected to the main bars of the reinforcing steel bar cages, the joint positions are staggered along the shaft interval according to the specification, and the staggering of the adjacent main bar joints is generally not less than 50cm. The split joint is only screwed by pulling. Through the cooperation of semicircle sleeve, lock sleeve and positive and negative screw thread, prevent semicircle sleeve rotation and drop, guarantee adjacent steel reinforcement cage's joint strength.

As shown in fig. 6, the water stop 18 used in this embodiment is a CP-type rubber water stop, before the water stop 18 is made, the core concrete 3 in the steel pipe pile is guaranteed to be completely solidified, the water stop is connected by adopting a hot-junction vulcanization method on site, and the water stop is required to be completely buried in the concrete during the pouring work of the micro-expansive concrete 4.

The steel pile casing 1 is internally filled with core concrete 3, and a pressure grouting method is adopted, namely a grouting pipe 10 is buried at the bottom of the steel pile casing 1, as shown in fig. 4, and the core concrete 3 is filled by full pressure grouting. The construction of the foundation raft 2 adopts micro-expansion concrete 4, as shown in fig. 7, and the micro-expansion concrete 4 is prepared by adding a certain expansion agent into ordinary concrete, so that the concrete can expand to a certain extent under the action of the expansion agent during hydration, thereby compensating the shrinkage of the concrete, preventing and curing concrete cracks and improving the concrete performance. In general, most of the concrete shrinks slightly after being dried, and the concrete added with the expanding agent does not shrink and has a certain free expansion amount with the lapse of time.

The pile end bottom expanding technology in the embodiment enlarges the stressed area of the pile bottom, greatly improves the bearing capacity of the pile, simultaneously, the manual hole digging pile can check the constitution condition of the rock soil layer of the pile bottom in more detail, ensures the consistency of the structure and design of the force holding soil layer of the pile end, and in addition, the manual hole digging bottom expanding pile has simple construction equipment, small pollution environment, no regional limitation and wider application range.

In the process of applying the static pressure pile technology, an optimal design construction scheme is formulated by combining analysis on the condition and the structural requirement of an engineering site, so that the rationality of each construction parameter of the static pressure pile is ensured. The construction sequence of the soil plug in the steel pile casing is manually excavated, so that the combination of the pile body and the soil body is more compact, and the bearing capacity of the whole foundation is greatly improved.

In order to make the technical scheme provided by the embodiment of the application clearer, an example is used for explaining the reinforcement construction method provided by the embodiment of the application.

1. Measuring and positioning: the axis is fixed and marked on the permanent fixing body before construction, so as to facilitate rechecking of the pile position. A short steel bar is nailed at the center of the pile position, and the sign is obvious. And rechecking the pile position by using a peripheral control axis after the static pressure equipment is basically in place, wherein the maximum deviation of the pile position is controlled to be not more than 20mm.

2. And opening holes on the raft 2: surveying the existing raft 2 foundation, determining the center of the opening of the raft 2 and the aperture of the opening, mechanically drilling the raft 2 foundation within the range of 4/5 of the designed aperture until the plain concrete cushion layer of the raft 2 foundation is completely exposed, manually removing the concrete of the raft 2 foundation within the range of 1/5 of the residual designed aperture, exposing the reinforcing steel bar net of the existing raft 2 foundation, and cutting off to form the round table-shaped hole 12.

3. Installing a main body structure of the static pressure equipment: the method comprises the steps of keeping a field flat, moving the machine to an upper position, hanging a steel pile casing 1 into an opening of a raft plate 2 which is opened, propping the lower side of the steel pile casing against a soil layer to be excavated, sequentially installing a steel base plate 11, a jack 5 and a counter-force frame 8 above the steel pile casing 1, wherein the steel base plate 11 is required to completely cover the steel pile casing 1 below the steel pile casing, the jack 5 is required to ensure complete contact with the steel base plate 11 below and the counter-force frame 8 above, and the counter-force frame 8 props against the upper frame beam 7.

4. Four steel strand anchor cables 13 are downwards driven into the bottom of the reaction frame 8, the integrity of the static pressure structure is improved, the steel strand anchor cables 13 can also 'tie up' the reaction frame 8, and the pressure of the reaction frame 8 to the frame beam 7 is reduced.

5. And checking the first section of steel pile casing 1 again by using an instrument to ensure that the pile position has no deviation, and in the static pressure process of the steel pile casing 1, if the steel pile casing 1 is not vertical, eccentric compression can be caused and the deviation of the horizontal position of the pile is increased, and the pile is adjusted to be vertical by referring to a theodolite.

6. Pile pressing: the oil pump 6 pressurizes the jack 5 and transmits the pressure downward to the steel casing 1 through the steel pad 11. The pressurization value is reflected by the pressure gauge 14. The relation between the soil penetration depth of the steel pile casing 1 and the reading of the pressure gauge 14 is carefully recorded in the pile pressing process so as to judge the quality and bearing capacity of the steel pile casing 1. When the reading of the pressure gauge 14 suddenly rises or falls, the oil pump 6 is turned off and depressurized, and the geological data are analyzed to judge whether the steel casing 1 encounters an obstacle or generates deformation, and the like.

7. Electric welding pile: when pile is connected, the upper and lower section steel casings 1 are required to be connected directly and firmly. The central line deviation of the upper and lower section steel pile casings 1 is not more than 2mm. Before the joint is welded, the cross section of the upper and lower section steel casings 1 is cleaned by using a steel wire ball brush, and the groove 15 is brushed until the metallic luster is exposed. During welding, the circumference of the groove 15 is symmetrically spot-welded at 4-6 points, the guide hoop can be dismantled after the upper section steel casing 1 and the lower section steel casing 1 are fixed, and then the welding is performed in a layered manner, and the welding is preferably symmetrically performed. The number of welding layers is preferably three, not less than two, and the welding slag in the inner layer must be cleaned and then the outer layer is welded. And naturally cooling the welded joint until pile sinking can be continued, naturally cooling the welded joint for no less than 8 minutes, and strictly disabling water cooling and welding to perform pile sinking.

8. Pile top elevation control: before construction, control points are arranged on buildings around the site, a leveling instrument is used for measuring the natural horizon, each pile is calculated and rechecked by two persons according to the related data of the drawing, the pile feeding depth is accurately calculated, and the pile top elevation deviation is ensured to be within the norm.

9. The jack 5 is adopted to press the steel casing 1 into the top surface of the middle wind mud layer in a segmented mode, and in order to ensure the perpendicularity of the pile, three sections of steel casings 1 are required to be pressed every time, and the center position and the perpendicularity need to be checked once. The theodolite tracks and adjusts the overall verticality of the static pressure equipment, and the verticality deviation value is less than 0.5%.

10. Dismantle the body structure of static pressure equipment: the oil pump 6 is regulated to release pressure of the jack 5, the reaction frame 8, the jack 5 and the steel backing plate 11 are dismounted from top to bottom in sequence, the site is leveled, and manual hole digging work is prepared.

11. Manual digging out the soil plug in the pile: when the earthwork is excavated, the process is performed from top to bottom, and the methods of digging holes, controlling the hollow feet and digging 'extending and suspending soil' are forbidden to be adopted, so that collapse accidents are prevented. Waste soil is filled into the movable bottom bucket, is vertically lifted out of the conveying hole and is conveyed to a specified waste slag field.

12. Pile end bottom expanding: as shown in fig. 2, manual hole digging and pile end bottom expanding are performed in the apoplexy mudstone, so that a manual hole digging and bottom expanding pile is formed for improving the bearing capacity of a single pile, and the pile end enters 4.0m of the apoplexy mudstone, and the bottom is expanded to 1600mm.

13. Layering and lowering reinforcement cages 17: the manufacturing of the reinforcement cage 17 is required to meet the design and specification requirements, the reinforcement cage 17 is placed to be vertically and slowly put down, collision of the protection wall is avoided, hanging ribs are required to be fixed at the orifice after the reinforcement cage 17 falls to the design elevation, and the reinforcement cage 17 is prevented from floating and sinking.

14. And (3) connection of reinforcement cages: first, the ends of two reinforcement cages to be connected are respectively inserted into the semicircular sleeves 21, ensuring that the insertion depth reaches half the sleeve length. Then, the lock sleeve 20 of the semicircular sleeve 21 is screwed tightly to be tightly attached to the semicircular sleeve 21, so that the stability and strength of the connector are ensured. Finally, the quality and stability of the connector are checked, and the condition that the connector is not loosened or deformed is ensured, and the split type straight thread sleeve 9 is installed.

15. Pouring core concrete 3: starting the stirrer, adding water and cement into the stirrer to form cement slurry, inserting the grouting pipe 10 into the pile bottom, filling sand gravel into the pile, opening a control valve, and injecting the cement slurry in the stirrer into the sand gravel pile body through the grouting pipe 10 by a pressure pump. The construction method for vibrating the concrete by grouting is not limited by construction space, and can be performed by inserting the grouting pipe 10 and the vibrating rod into the concrete, so that the construction process is simple, the construction efficiency is high, the quality of the concrete formed after the construction is high, the construction period is short, and the cost is low.

16. Recovering raft steel bars 19 on the upper layer and the lower layer of the raft 2, and making water stops 18: as shown in fig. 6, after the exposed raft reinforcement 19 inside the raft 2 is wiped clean, a new raft reinforcement 19 is welded and fixed on the broken reinforcement. The water stop 18 is partially or fully poured and buried in the concrete during the concrete pouring process. Before concrete is poured, the water stop 18 is kept flat at the interface part, the joint part is bonded and fastened, then the water stop 18 is fully poured and tamped with proper force, and the concrete is vibrated to position the water stop 18 so as to ensure that the water stop is well combined with the concrete, so that the water stop effect is not influenced.

17. Pouring micro-expansion concrete 4: as shown in fig. 7, the surface contacted with the concrete should be sufficiently wet before pouring, the concrete should be poured quickly and continuously once, and the concrete is compacted by vibrating with an inserted vibrator and cannot leak vibration, overshock or undershock.

18. And (3) hole sealing: and (3) after the micro-expansive concrete 4 is finally solidified, water is sprayed for maintenance, the maintenance time is not less than 14d, the concrete is kept in a wet state constantly, construction equipment is withdrawn, the site is leveled, and the reinforcement of the high-rise building foundation is completed.

The anchor rod static pressure steel pile casing is combined with the process of manually excavating the soil plug in the steel pile casing, so that the problem of construction safety of the manual hole-excavating pile is solved, slurry is not needed, the quality of the pile body is easy to ensure, and civilized construction can be achieved; on the other hand, the pile end of the artificial hole-digging club-footed pile has no sediment, and the end resistance of the wind-driven rock stratum in the pile end is fully exerted, so that the aim of reinforcing the foundation is fulfilled.

Compared with the prior art, the beneficial effects are mainly represented in that:

1. the foundation reinforcement of the high-rise building adopts a technology of combining an anchor rod static pressure steel pile casing with manual excavation of a soil plug in the steel pile casing, and the method of manually excavating the soil plug in the pile and expanding the bottom of the pile end can be constructed in a limited space, is not easy to be limited by construction sites and construction machinery, has simple construction flow without noise, can quantitatively observe the whole pile sinking process, and has the advantages of ensuring the bearing capacity of the pile, and the like.

2. The bearing capacity of the whole foundation can be greatly improved by expanding the bottom of the pile, so that the pile body and the soil body are combined more compactly, and the bearing capacity of the whole foundation is also greatly improved.

3. The economic benefit is high, the engineering cost of the static pressure pile is probably higher than that of the filling pile, but if the factors of high bearing capacity (single-side transmission force is higher), guaranteed pile body quality, short construction period and the like are considered, the comprehensive benefit is still higher than that of the filling pile, and the static pressure pile has higher engineering applicability.

According to the anchor rod static pressure steel pile casing hole digging pile process, on one hand, the anchor rod static pressure steel pipe pile can be used as a protection wall to successfully cut off underground water, the construction speed is high, reliable safety guarantee can be provided for manual hole digging, and the problem of construction safety of the manual hole digging pile is solved; on the other hand, the artificial hole digging pedestal pile can fully exert the end resistance of the wind formation layer at the pile end, solve the engineering problem that the mudstone bearing layer is easy to soften when meeting water, and ensure that the characteristic value of the bearing capacity of a single pile meets the design requirement.

While the foregoing description of the embodiments of the present application has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the application, but rather, it is intended to cover all modifications or variations within the scope of the application as defined by the claims of the present application.

Finally, it should be noted that, if not conflicting, the embodiments of the present application and the features of the embodiments may be combined with each other, which are all within the protection scope of the present application. In addition, although the steps are listed in order of 1, 2, 3 …, in some cases, the steps shown or described may be performed in an order other than that described herein.

Claims (10)

1. A method of reinforcing a foundation of an existing structure in a confined space, comprising:

forming pile pressing holes by perforating the raft, and hanging pile barrels into the pile pressing holes, wherein the pile barrels are barrels with openings at two ends;

pressing the pile barrels into the foundation below the raft from the pile pressing holes section by section to a preset depth;

digging out the soil plug in the pile cylinder and transporting out of the pile cylinder, and expanding the bottom of the pile end to ensure that the aperture of the bottom of the pile cylinder is larger than that of the pile cylinder;

pouring core filling concrete into the pile cylinder and the reaming at the bottom of the pile cylinder, recovering the raft and sealing the holes.

2. The method of claim 1, wherein the raft openings comprise:

determining the position and the aperture of the opening, and mechanically drilling the raft foundation within a preset range of the center of the opening, wherein the preset range is smaller than the aperture of the opening, manually removing concrete of the raft foundation within the remaining range of the opening, exposing a reinforcing mesh of the existing raft foundation, and cutting off to form a pile pressing hole.

3. The method for reinforcing a foundation of an existing structure in a limited space according to claim 1, wherein the installation of the main structure of the static pressure equipment after the formation of the pile pressing hole comprises: hanging a pile cylinder into the pile pressing hole, propping against a soil layer to be excavated below the pile cylinder, and sequentially installing a steel backing plate, a jack and a counterforce frame above the pile cylinder;

and after the pile barrels are pressed into the foundation below the raft section by section from the pile pressing holes to a preset depth, the steel backing plate, the jack and the reaction frame are disassembled.

4. A method of reinforcing a foundation of an existing structure in a confined space according to claim 3, wherein after the installation of the main structure of the hydrostatic apparatus, steel strand anchor cables are driven downwardly into the bottom of the reaction frame, the upper ends of the steel strand anchor cables are connected to the reaction frame, and the lower ends of the steel strand anchor cables are connected to the raft.

5. A method of reinforcing an existing structure foundation in a confined space as set forth in claim 1 wherein said pile casing is pressed into a stroke-forming mud layer.

6. A method of reinforcing a foundation of an existing structure in a confined space as set forth in claim 1, wherein after the earth plug and pile tip are excavated and the bottom is enlarged, the pile casing is lined with underlying reinforcement cages and adjacent reinforcement cages are connected.

7. The method of reinforcing a foundation of an existing structure in a confined space of claim 1, wherein casting core concrete into the pile casing and the bottom counterbore of the pile casing comprises:

after the grouting pipe is inserted into the pile bottom, sand gravel is filled into the pile, cement slurry is injected into the sand gravel pile body through the grouting pipe, and concrete is vibrated by a vibrating rod.

8. The method for reinforcing a foundation of an existing structure in a limited space according to claim 1, wherein the micro-expansive concrete is poured after the raft is restored, and the micro-expansive concrete is cured by sprinkling water after final setting.

9. A reinforcement system for use in a method of reinforcing a foundation of an existing structure in a confined space as claimed in any one of claims 1 to 8, comprising: pile cylinder, jack, counterforce frame, steel backing plate, steel strand anchor cable, steel reinforcement cage and connecting assembly;

pile cylinder is installed in the stake hole of raft, steel backing plate sets up pile cylinder upside, the jack sets up steel backing plate upside, the reaction frame sets up the jack upside, steel strand wires anchor rope upper end is connected the reaction frame, the lower extreme is connected the raft, the steel reinforcement cage below is arrived inside the pile cylinder, coupling assembling connects two adjacent steel reinforcement cages.

10. The reinforcement system of claim 9, wherein two adjacent reinforcement cages have first and second reinforcement bars, respectively, the ends of the first and second reinforcement bars are threaded, and the threads of the first and second reinforcement bars are in opposite directions; the connecting assembly comprises a first sleeve, a second sleeve, a first lock sleeve and a second lock sleeve, wherein two ends of the first sleeve are respectively in threaded connection with the first steel bars and the second steel bars, two ends of the second sleeve are respectively in threaded connection with the first steel bars and the second steel bars, the first sleeve and the second sleeve are combined into a cylinder, the first lock sleeve is in threaded connection with the first end of the cylinder, and the second lock sleeve is in threaded connection with the second end of the cylinder.