Deep soft soil field stiff pile composite foundation grouting device based on geotechnical bags

Abstract

The utility model discloses a deep soft soil field stiff pile composite foundation grouting device based on a soilbag, which comprises an expanded-base grouting pipeline and a flexible soilbag, the center of the expanded-base grouting pipeline is provided with a grouting channel penetrating up and down, the lower end of the expanded-base grouting pipeline is provided with the flexible soilbag, and the flexible soilbag is arranged in the expanded-base grouting pipeline. And an opening in the upper end of the flexible geotechnical bag is communicated with the grouting channel. Grouting is conducted in the grouting channel of the expanded-base grouting pipeline, the flexible soil engineering bag installed at the lower end of the expanded-base grouting pipeline is used for receiving grouting, and the overall forming shape of grouting slurry is intervened and controlled, so that it is guaranteed that the final shape reaches the ideal state, the grouting construction problem of the expanded head is solved, and the construction quality of the expanded head is guaranteed. And meanwhile, after grouting is completed in the flexible soil bag, the fiber tissue of the flexible soil bag becomes the internal tissue of the expanded head, the structural stability of the expanded head can be further improved, and therefore the structural stability of the whole stiff composite pile is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of composite foundations, in particular to a geobag-based composite foundation grouting device for reinforced piles in thick soft soil sites. Background Art

[0002] As a new type of composite pile, rigid composite pile has been widely used in the eastern coastal areas due to its excellent performance in reinforcing soft soil and other weak soil layers. During the construction of rigid composite piles in soft soil sites, it is often necessary to inject grout into the bottom to form an "enlarged head" to enhance the bearing and pull-out resistance of the rigid composite pile; however, during on-site construction, the shape of the grouting at the bottom of the pile top is difficult to control, resulting in difficulty in ensuring the quality of the expanded head.

[0003] Therefore, there is an urgent need for a geobag-based reinforced pile composite foundation grouting device for deep soft soil sites to solve the grouting construction problem of the "enlarged head" used to enhance the bearing and pull-out properties of the reinforced composite piles. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a geobag-based composite foundation grouting device for a reinforced pile in a thick soft soil field, so as to solve the grouting construction problem of an "enlarged head" for enhancing the bearing and pull-out resistance of the reinforced composite pile.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A geobag-based reinforced pile composite foundation grouting device for deep soft soil sites, characterized in that it includes an expanded bottom grouting pipe and a flexible geobag, the center of the expanded bottom grouting pipe is provided with a grouting channel running through it from top to bottom, a flexible geobag is installed at the lower end of the expanded bottom grouting pipe, and the upper end opening of the flexible geobag is connected to the grouting channel.

[0007] To optimize the above technical solutions, the specific measures taken also include:

[0008] Furthermore, the flexible geobags include at least three, the three flexible geobags are nested with each other, and the upper openings of the three flexible geobags are all connected to the grouting channel, and the sizes of the three nested flexible geobags gradually increase from the inside to the outside.

[0009] Furthermore, a geobag keel is installed on the inner side or the outer side of the flexible geobag.

[0010] Furthermore, the geobag keel is a spherical skeleton structure.

[0011] Furthermore, the geobag keel is made of high-elastic steel wire.

[0012] Furthermore, it also includes a clamping sleeve, and an annular groove for the clamping sleeve to be inserted from the bottom is opened in the inner wall of the lower end of the grouting channel of the bottom expansion grouting pipe, and the flexible geotextile bag is detachably clamped and fixed between the outer wall of the clamping sleeve and the annular groove by the clamping sleeve.

[0013] Furthermore, a circle of grooves is provided on the outer wall of the clamping sleeve, and the grooves are used to secure the flexible geobag sleeved on the clamping sleeve.

[0014] Furthermore, it also includes a hydraulic protection head, which includes two mutually symmetrical hydraulic protection sleeves, and the opposite surfaces of the two hydraulic protection sleeves are provided with cavities, and two hydraulic tracks are symmetrically provided in the inner wall of the lower end of the bottom expansion grouting pipe along the axial direction of the bottom expansion grouting pipe, and the two hydraulic tracks are respectively connected to external pressure-applying equipment through hydraulic pipes, and pistons are provided in the hydraulic tracks, and the upper end of the piston is provided with a push rod extending out of the hydraulic track, and a channel for the push rod to move up and down is also provided above the hydraulic track, and a sliding channel connected to the outside is provided on the side wall of the moving channel, and a connecting rod is connected to the push rod, and the connecting rod is slidably arranged in the sliding channel, and a hydraulic protection sleeve is hinged on one end extending out of the sliding channel, and the two symmetrically arranged hydraulic protection sleeves can cover the outer side of the lower end of the bottom expansion grouting pipe through the cavity, and protect the flexible geobag in the cavity of the two hydraulic protection sleeves.

[0015] Furthermore, the lower end of the hydraulic protection head is in a cone shape with the tip pointing downward.

[0016] Furthermore, the position where the push rod passes through the hydraulic track is slidably and sealedly connected to the hydraulic track.

[0017] The beneficial effects of the utility model are:

[0018] When in use, the utility model injects grout into the grouting channel of the expanded bottom grouting pipe, uses a flexible geotextile bag installed at the lower end of the expanded bottom grouting pipe to receive the grouting, and intervenes and controls the overall forming shape of the grouting slurry, thereby ensuring that the final shape reaches an ideal state, solving the grouting construction problem of the "expanded head" used to enhance the bearing and pull-out resistance of the rigid composite pile, and ensuring the construction quality of the "expanded head". At the same time, after the grouting is completed in the flexible geotextile bag, the fiber tissue of the flexible geotextile bag will become the internal tissue of the expanded head, which can further improve the structural stability of the expanded head, thereby increasing the stability of the entire rigid composite pile structure.

[0019] The utility model intervenes and controls the overall shape of the grouting slurry by injecting grout into a multi-layer flexible geobag with a steel keel, thereby ensuring that the final shape reaches an ideal state and the construction quality is guaranteed. After the cement soil pile is mixed, the head expansion effect can be controlled by injecting grout into the bottom expansion grouting pipe with a prefabricated flexible geobag at the bottom. The overall steps do not add any additional construction process, and the construction consumables are inexpensive. After the grouting is completed in the flexible geobag, the fiber tissue of the flexible geobag and the steel keel become the expansion head skeleton, which can further improve the structural stability of the expansion head. After that, the inner core of the rigid composite pile can be inserted according to the design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of a geobag-based composite foundation grouting device for reinforced piles in thick soft soil fields proposed by the utility model;

[0021] Figure 2 This is an enlarged view of the partial structure of a geobag-based composite foundation grouting device for a thick soft soil site;

[0022] Figure 3 A schematic diagram of the closed state of a hydraulic protection head of a geobag-based composite foundation grouting device for a thick soft soil site;

[0023] Figure 4 A schematic diagram of the opening state of the hydraulic protection head of a geobag-based composite foundation grouting device for a thick soft soil site;

[0024] Figure 5 A schematic diagram of the use of a flexible geobag in a geobag-based composite foundation grouting device for a thick soft soil field proposed by the utility model;

[0025] Figure 6 This is a schematic diagram of the connection between the enlarged head and the inner core of the rigid composite pile after the use of the geobag-based rigid pile composite foundation grouting device for thick soft soil sites proposed by the utility model;

[0026] Figure 7 A schematic diagram of the use of a mixing pile Figure 1 ;

[0027] Figure 8 A schematic diagram of the use of a mixing pile Figure 2 .

[0028] Figure markings: 1-mixing pile, 2-threaded blades of mixing pile, 3-slurry outlet, 4-drill bit, 5-outer core of rigid composite pile, 6-mixing soil of expansion section, 7-bottom grouting pipe of expansion, 8-grouting channel, 9-hydraulic track, 10-hydraulic protection head, 11-flexible geobag, 12-geobag keel, 13-geobag crushed fiber, 14-final diffusion section of expansion head, 15-inner core of rigid composite pile. DETAILED DESCRIPTION

[0029] The utility model is described in detail below with reference to the accompanying drawings.

[0030] As attached Figure 1 As shown, a geobag-based reinforced pile composite foundation grouting device for deep soft soil field according to an embodiment of the utility model comprises an expanded bottom grouting pipe 7 and a flexible geobag 11. A grouting channel 8 running through the expanded bottom grouting pipe 7 is provided at the center thereof, and a flexible geobag 11 is installed at the lower end of the expanded bottom grouting pipe 7, and the upper end opening of the flexible geobag 11 is communicated with the grouting channel 8.

[0031] When the utility model device is in use, grouting is injected into the grouting channel 8 of the bottom expansion grouting pipe 7, and the flexible geotextile bag 11 installed at the lower end of the bottom expansion grouting pipe 7 is used to receive the grouting, and the overall forming shape of the grouting slurry is intervened and controlled, so as to ensure that the final shape reaches an ideal state, solve the grouting construction problem of the "enlarged head" used to enhance the bearing and pull-out resistance of the rigid composite pile, and ensure the construction quality of the "enlarged head". At the same time, after the grouting is completed in the flexible geotextile bag 11, the fiber tissue of the flexible geotextile bag 11 will become the internal tissue of the enlarged head, which can further improve the structural stability of the enlarged head, thereby increasing the stability of the entire rigid composite pile structure.

[0032] In another specific embodiment, the flexible geobag 11 includes at least three, three flexible geobags 11 are nested with each other, and the upper end openings of the three flexible geobags 11 are connected to the grouting channel 8, and the sizes of the three nested flexible geobags 11 gradually increase from the inside to the outside. In this embodiment, the three layers of flexible geobags 11 are all spherical after being filled, the innermost flexible geobag 11 is the smallest, and the outermost flexible geobag 11 is the largest. When in use, the three layers of flexible geobags 11 are all woven with stacked flexible fibers, and each layer of flexible geobags 11 is filled with slurry one by one. The innermost flexible geobag 11 expands first, and the staggered fibers of the flexible geobag 11 open until the flexible geobag 11 is broken, and the slurry can diffuse into the next larger flexible geobag 11. In this way, the slurry is better constrained and shaped by the three layers of flexible geobags 11, thereby forming a stable and reliable enlarged head structure.

[0033] In another specific embodiment, a geobag keel 12 is attached to the inner or outer side of the flexible geobag 11. When in use, the above three layers of flexible geobags 11 can be set, and the geobag keel 12 can be set outside the innermost flexible geobag 11, or the geobag keel 12 of corresponding size can be set outside each layer; specifically, 8 staggered and highly elastic steel keels can be set outside each layer of flexible geobag 11 as geobag keels 12. After each layer is filled with slurry, the flexible geobag 11 gradually expands and lifts the steel keel, so that it deforms in a circular shape according to the expansion of the flexible geobag 11. After that, as the flexible geobag 11 is about to be destroyed, the scattered fibers of the flexible geobag 11 open until the flexible geobag 11 is broken, only the steel keel is left, and the slurry continues to diffuse into the next larger flexible geobag 11. At this time, the steel keel can be used as the internal steel bar of the enlarged head structure to become the enlarged head frame to increase the strength and stability of the enlarged head structure.

[0034] Among them, the geobag keel 12 is a spherical skeleton structure. In this way, the enlarged head structure to be formed is increased to fit the final shape. Among them, the geobag keel 12 is made of high-elastic steel wire. In this way, it is convenient to gradually assist in the shaping of the slurry according to the expansion of the flexible geobag 11. The geobag keel 12 is located on the outside of each layer of flexible geobag 11. It is initially in a contracted state. As the slurry is injected, it gradually opens with the expansion of the flexible geobag 11. After the flexible geobag 11 is broken, only eight curved geobag keels 12 similar to the lantern skeleton are left.

[0035] In another specific embodiment, a clamping sleeve is also included, and an annular groove for inserting the clamping sleeve from the bottom is provided in the inner wall of the lower end of the grouting channel 8 of the bottom-expanding grouting pipe 7, and the flexible geobag 11 is detachably clamped and fixed between the outer wall of the clamping sleeve and the annular groove by the clamping sleeve. Specifically, the above-mentioned three-layer flexible geobag 11 and the bottom-expanding grouting pipe 7 can be connected by the clamping sleeve to ensure that they will not be damaged prematurely due to the grouting pressure during the grouting process; when the grouting is completed and the three-layer flexible geobag 11 is damaged, the bottom-expanding grouting pipe 7 can be recovered, the clamping sleeve can be opened, and a new flexible geobag 11 can be reinstalled to prepare for the next construction.

[0036] The outer wall of the clamping sleeve is provided with a circle of grooves, which are used to tighten the flexible geobag 11 sleeved on the clamping sleeve. Therefore, when in use, the opening of the flexible geobag 11 can be sleeved on the outer wall of the tight sleeve first, and then the flexible geobag 11 can be tightened in the groove with a rope, and finally the clamping sleeve with the flexible geobag 11 is inserted into the annular groove of the bottom expansion grouting pipe 7 to complete the installation.

[0037] As attached Figure 2As shown, in another specific embodiment, it also includes a hydraulic protection head 10, which includes two mutually symmetrical hydraulic protection sleeves, and the opposite surfaces of the two hydraulic protection sleeves are provided with cavities, and two hydraulic rails 9 are symmetrically provided in the inner wall of the lower end of the bottom expansion grouting pipe 7 along the axial direction of the bottom expansion grouting pipe 7, and the two hydraulic rails 9 are respectively connected to external pressure-applying equipment through hydraulic pipes, and pistons are provided in the hydraulic rails 9. The upper end of the piston is provided with a push rod extending out of the hydraulic rail 9, and a channel for the push rod to move up and down is also provided above the hydraulic rail 9. A sliding channel connected to the outside is provided on the side wall of the moving channel, and a connecting rod is connected to the push rod, which is slidably arranged in the sliding channel, and a hydraulic protection sleeve is hinged on one end extending out of the sliding channel, and the two symmetrically arranged hydraulic protection sleeves can be covered on the outer side of the lower end of the bottom expansion grouting pipe 7 through the cavity, and the flexible geobag 11 is protected in the cavity of the two hydraulic protection sleeves.

[0038] Therefore, when using, if the attached Figure 3 and attached Figure 4 As shown, the flexible geobag 11 can be protected by the hydraulic protection head 10 to prevent the flexible geobag 11 from being damaged before use, which may cause other pouring problems. Specifically, when the bottom expansion grouting pipe 7 is inserted, the two symmetrical hydraulic protection sleeves are connected to each other and closed, and the lower end of the bottom expansion grouting pipe 7 and the flexible geobag 11 are protected inside; when the bottom expansion grouting pipe 7 is inserted into the specified position, the hydraulic pipe is connected to the external pressure device to apply pressure to the hydraulic track 9, and then the piston is lifted, and the push rod on the piston drives the connecting rod and the hydraulic protection sleeve connected to the connecting rod to move up, the push rod moves up in the moving channel, and the connecting rod slides upward in the sliding channel. The hydraulic protection sleeve naturally opens to both sides due to the hinge with the connecting rod and the extrusion of the outer wall of the bottom expansion grouting pipe 7, until it stays on both sides of the bottom expansion grouting pipe 7 and exposes the flexible geobag 11. In this embodiment, the push rod and the connecting rod can also be hinged, and the upper end of the hydraulic protection sleeve can be set to be open so that there is a gap between it and the bottom expansion grouting pipe 7, thereby increasing the smoothness of the movement of the hydraulic protection sleeve.

[0039] The lower end of the hydraulic protection head 10 is a cone with the tip pointing downward, so that the convenience of insertion can be increased.

[0040] Wherein, the position where the push rod passes through the hydraulic track 9 is slidably sealed and connected with the hydraulic track 9. In this way, the sealing inside the hydraulic track 9 is guaranteed.

[0041] Before the use of the device of the utility model, a cement soil mixing pile 1 must be used for construction. The required cement soil mixing pile 1 can adopt a steel structure. After the pressure is applied to the upper part to sink the pressure, the pile foundation construction is turned underground; the mixing pile threaded blade 2 is attached to the mixing pile 1, and the soil on the side of the pile can be mixed; the slurry outlet 3 on the mixing pile 1 is arranged at the lower end of the mixing pile 1, and the water outlet is arranged at the drill bit 4 at the lowermost end, and the rest are slurry outlets 3. The water outlet makes it easier for the mixing pile 1 to descend, and the slurry outlet 3 cooperates with the mixing pile threaded blades 2 to mix the soil on the side of the pile into cement soil; the drill bit 4 can adopt a steel head, which can crush the soil structure by rotation, and is provided with a water outlet, and water is discharged while drilling, so that the structure is easier to descend.

[0042] The cement soil section as the outer core 5 of the rigid composite pile refers to the cement soil pile formed by the mixing pile threaded blades 2 during the sinking stage of the mixing pile 1.

[0043] The expanded section mixed soil 6 is a plain mixed soil with a larger diameter that is mixed by the threaded blades 2 of the mixing pile under a higher water pressure, which is convenient for grouting into the soil to form an expanded head structure in the later stage.

[0044] The bottom expansion grouting pipe 7 in the utility model device is a steel pipe inserted after the expansion section is stirred. It contains a grouting channel 8 inside, and its depth reaches the lower part of the cement soil pile body. Its lower end is connected to the hydraulic protection head 10 and the three-layer flexible geobag 11 with geobag keel 12. After the grouting is completed in the three-layer flexible geobag 11, the bottom expansion grouting pipe 7 is pulled back for recycling. When in use, the upper part of the grouting channel 8 is connected to the grouting equipment, and the lower part is clamped with the flexible geobag 11 through a clamping sleeve or other mechanical clamps.

[0045] In this embodiment, the hydraulic protection head 10 is made of steel material, and is closed during the sinking stage of the bottom expansion grouting pipe 7 to protect the internal three-layer flexible geobag 11 from being squeezed and damaged during the sinking process, and waits until the bottom expansion grouting pipe 7 sinks to the specified position and moves upward and passively opens, exposing the flexible geobag 11. In this embodiment, the hydraulic protection head 10 can also be connected to the hydraulic track 9 for sliding sealing as needed, and multiple oil pipes are used to extend from the inner wall of the bottom expansion grouting pipe 7 to the track 9, and the oil pipes are used to control the opening of the hydraulic protection head 10, or control the upward movement of the hydraulic protection head 10, and specifically control the oil pressure in each oil pipe according to the construction stage combination, so that the hydraulic protection head 10 is opened and displaced successively as expected.

[0046] The three-layer flexible geobag 11 is installed on the lower side of the bottom expansion grouting pipe 7. The three-layer flexible geobag 11 is circular after being filled, with the innermost geobag being the smallest and the outermost geobag being the largest. The three-layer flexible geobag 11 is woven from stacked flexible fibers. Each layer of geobag contains 8 steel keels as geobag keels 12. After each layer is filled with slurry, the flexible geobag 11 gradually expands and lifts up the steel keel, causing it to deform in a circular shape in accordance with the expansion of the flexible geobag 11. After that, as the flexible geobag 11 is about to be destroyed, the scattered fibers of the flexible geobag 11 open until the flexible geobag 11 is broken, leaving only the steel keel, allowing the slurry to diffuse into the next larger flexible geobag 11. The geobag broken fibers 13 are the interlaced banded fiber tissues produced after the geobag is broken. The final diffusion section 14 of the enlarged head is a shape formed when the slurry freely diffuses outward after the flexible geobags 11 are broken, and the flexible geobag 11 fibers and the geobag keel 12 inside the enlarged head serve as the skeleton of the enlarged head section.

[0047] The inner core 15 of the rigid composite pile is a prefabricated pipe pile, which can be inserted into cement soil with a long core, a short core, or an equal core. When the inner core 15 of the rigid composite pile is a long core, it can be inserted into the enlarged head.

[0048] The use of the device of the utility model comprises the following steps:

[0049] Step 1: As attached Figure 7 As shown, the cement soil mixing pile 1 is used to construct the cement soil section of the outer core 5 of the rigid composite pile, while the threaded blades 2 of the mixing pile rotate and the slurry outlet 3 discharges slurry; the mixing is stopped after the expansion section is constructed.

[0050] Step 2: Expand the head section downwards. At this time, the slurry outlet 3 does not discharge slurry, and only the water outlet discharges water. By speeding up the rotation speed of the rotating head and increasing the water outlet pressure, as shown in the attached Figure 8 As shown, the enlarged head section can stir deeper soil than the upper cement soil pile body section.

[0051] Step 3: After the soil of the expanded section is mixed, pull out the mixing pile 1, and quickly insert the bottom expansion grouting pipe 7 with three layers of flexible geotextile bags 11 at the bottom before the cement soil solidifies.

[0052] Step 4: Open the hydraulic protection head 10 through the hydraulic switch;

[0053] Step 5: As attached Figure 5 As shown, grout is injected into the grouting channel 8, and the first layer of flexible geobags 11 is gradually filled up to form a circular shape;

[0054] Step 6: After the first layer of flexible geobags 11 is broken, the slurry flows into the second layer of flexible geobags 11, and the whole takes on a larger round shape.

[0055] Step 7: After the second layer of flexible geobag 11 is broken, the slurry flows into the third layer of flexible geobag 11, and the whole takes on a larger round shape.

[0056] Step 8: After the third layer of flexible geobag 11 ruptures, the slurry flows into the mixed soil. At this time, the slurry is left without being constrained by the flexible geobag 11, but due to the intervention of the three layers of flexible geobag 11, the slurry has taken a rough shape. At the same time, the fiber tissue of the flexible geobag 11 and the steel keel become the expansion head skeleton, and on this basis, the final diffusion section of the expansion head with excellent quality is formed. After the construction of the expansion head is completed, the grouting pipe is pulled back.

[0057] Step 9: As attached Figure 6 As shown, the rigid composite pile inner core 15 is inserted according to the design requirements. If a long core is encountered, the long core can be inserted into the enlarged head.

[0058] In this solution, geobags, as a kind of high molecular polymer, are a flexible material and play an important role in geotechnical engineering construction. By using geobags, a flexible structure that takes into account both practicality and economy, in the process of bottom expansion grouting, the shape of the "enlarged head" can be controlled at a very low cost and with convenient technology to ensure the quality of the project. In this solution, during the grouting process, the flexible geobag 11 intervenes in the shape formation process of the lower enlarged head to make its shape uniform. After the three layers of flexible geobags 11 are broken, the fiber tissue and steel keel of the flexible geobag 11 become the enlarged head skeleton, further improving the structural stability of the enlarged head. Compared with traditional construction methods, the quality of the enlarged head is guaranteed to be stable with extremely low cost consumables and simple construction process.

[0059] The utility model has the following beneficial effects:

[0060] 1. The utility model intervenes and controls the overall shape of the grouting slurry by injecting grout into the multi-layer flexible geotextile bag 11 with a steel keel, thereby ensuring that the final shape reaches an ideal state and the construction quality is guaranteed.

[0061] 2. After the cement soil pile is mixed, grouting is injected into the bottom expansion grouting pipe 7 with a prefabricated flexible geotextile bag 11 at the bottom to control the head expansion effect. The overall steps do not add any additional construction process, and the construction consumables are inexpensive.

[0062] 3. After the grouting is completed in the flexible geotextile bag 11, the fiber tissue of the flexible geotextile bag 11 and the steel keel become the enlarged head frame, which can further improve the structural stability of the enlarged head. After that, the rigid composite pile core 15 is inserted according to the design requirements.

[0063] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. used in the utility model are only for the convenience of description and are not used to limit the scope of implementation of the utility model. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the utility model without substantially changing the technical content.

[0064] The above are only preferred implementations of the utility model. The protection scope of the utility model is not limited to the above embodiments. All technical solutions under the idea of ​​the utility model belong to the protection scope of the utility model. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the utility model should be regarded as the protection scope of the utility model.

Claims

1. A geobag-based composite foundation grouting device for reinforced piles in thick soft soil, characterized by: The invention comprises a bottom-enlarged grouting pipe (7) and a flexible geobag (11), wherein a grouting channel (8) penetrating from top to bottom is provided at the center of the bottom-enlarged grouting pipe (7), a flexible geobag (11) is installed at the lower end of the bottom-enlarged grouting pipe (7), and the upper end opening of the flexible geobag (11) is connected to the grouting channel (8); the flexible geobag (11) comprises at least three, the three flexible geobags (11) are mutually nested, and the upper end openings of the three flexible geobags (11) are all connected to the grouting channel (8), and the sizes of the three mutually nested flexible geobags (11) gradually increase from the inside to the outside; and a geobag keel (12) is installed on the inner side or the outer side of the flexible geobag (11).

2. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 1 is characterized by: The geobag keel (12) is a spherical skeleton structure.

3. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 1 is characterized by: The geobag keel (12) is made of high-elastic steel wire.

4. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 1 is characterized by: It also includes a clamping sleeve, wherein the lower end inner wall of the grouting channel (8) of the bottom expansion grouting pipe (7) is provided with an annular groove into which the clamping sleeve can be inserted from the bottom, and the flexible geotextile bag (11) is detachably clamped and fixed between the outer wall of the clamping sleeve and the annular groove by the clamping sleeve.

5. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 4 is characterized by: The outer wall of the clamping sleeve is provided with a circle of grooves, and the grooves are used to secure the flexible geotextile bag (11) sleeved on the clamping sleeve.

6. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 1, characterized in that: It also includes a hydraulic protection head (10), the hydraulic protection head (10) including two mutually symmetrical hydraulic protection sleeves, the opposite surfaces of the two hydraulic protection sleeves are each provided with a cavity, two hydraulic tracks (9) are symmetrically provided in the inner wall of the lower end of the bottom expansion grouting pipe (7) along the axial direction of the bottom expansion grouting pipe (7), the two hydraulic tracks (9) are respectively connected to external pressure devices through hydraulic pipes, the hydraulic tracks (9) are each provided with a piston, the upper end of the piston is provided with a push rod extending out of the hydraulic track (9), the upper part of the hydraulic track (9) is also provided with a channel for the push rod to move up and down, the side wall of the moving channel is provided with a sliding channel connected to the outside, the push rod is connected to a connecting rod, the connecting rod is slidably arranged in the sliding channel, and one end extending out of the sliding channel is hinged with a hydraulic protection sleeve, the two symmetrically arranged hydraulic protection sleeves can cover the outer side of the lower end of the bottom expansion grouting pipe (7) through the cavity, and protect the flexible geotextile bag (11) in the cavity of the two hydraulic protection sleeves.

7. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 6, characterized in that: The lower end of the hydraulic protection head (10) is in the shape of a cone with the tip pointing downward.

8. The grouting device for composite foundation of reinforced piles in thick soft soil based on geobags according to claim 6, characterized in that: The position where the push rod passes through the hydraulic track (9) is slidably and sealingly connected to the hydraulic track (9).

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