Reverse vacuum preloading reinforcing system and construction method

Abstract

The invention discloses a reverse vacuum preloading reinforcing system and a construction method. The system comprises a reverse vacuum preloading unit and a closed operation cavity unit. The reverse vacuum preloading unit comprises a prefabricated horizontal drainage body arranged at the bottom of the soft soil layer, a vacuum main pipe arranged in the prefabricated horizontal drainage body and led out upwards, a plurality of vertical drainage plates and a geotextile and geomembrane sealing layer covering the surface of a treatment area. The bottom end of each vertical drainage plate and the prefabricated horizontal drainage body are bound in advance to form a grid-shaped integrated drainage structure. The closed operation cavity unit is integrally sunk or constructed in a soil body, a plurality of vacuum pumps are arranged in the deep part in the closed operation cavity unit and connected with a vacuum main pipe through a quick connection structure, and a water suction pump is arranged at the top and used for timely draining accumulated water in the cavity. According to the system, negative pressure acts on a bottom drainage channel in a deep near field, the negative pressure transmission distance is shortened, on-way attenuation is reduced, and the consolidation efficiency and vacuum stability of deep saturated soft soil are improved through bottom short-path drainage.

Description

Technical Field

[0001] This invention belongs to the field of foundation treatment technology, and relates to the reinforcement of deep soft soil foundations under complex conditions such as coastal mudflats, reclamation projects, port projects and river and lake shores. Specifically, it relates to a reverse vacuum preloading reinforcement system and construction method. Background Technology

[0002] Soft soil typically exhibits high water content, high compressibility, and low shear strength, necessitating effective consolidation treatment before construction. Vacuum preloading, due to its simplicity, environmental friendliness, and significant consolidation effect, has been widely adopted in soft soil foundation treatment. However, traditional vacuum preloading relies primarily on top drainage, whose drainage path lengthens significantly with increasing treatment depth, resulting in a noticeable delay in consolidation time. To shorten the drainage path, reverse vacuum preloading technology has been proposed. This technology involves placing drainage channels at the bottom of the soil mass, guiding pore water downwards to accelerate soil consolidation.

[0003] However, existing reverse vacuum preloading systems still face many limitations in engineering applications. Although some technologies have attempted to achieve bottom drainage by inserting drainage boards upside down to the surface and pumping them out from the ground, the deep pumping pipelines are quite long, and significant losses easily occur during the transmission of vacuum along the pipelines. Furthermore, the effective vacuum pressure at the bottom is partially offset by the overlying water head pressure, making it difficult to achieve the design value of vacuum pressure acting on the deep soil, thus affecting consolidation efficiency. At the same time, existing systems generally lack auxiliary units for the centralized arrangement of multiple vacuum pumps, water pumps, and gas-liquid separation structures in a sealed working chamber, making it difficult to guarantee overall sealing and stability. Construction layouts are also scattered, and operation and maintenance are complex. These shortcomings prevent reverse vacuum preloading technology from achieving the expected results in the treatment of deep soft soil foundations. Therefore, it is necessary to provide a reverse vacuum preloading system that can construct a short-path drainage system at the bottom of the soil and ensure that negative pressure acts stably in the deep near-field on the bottom drainage channel. Summary of the Invention

[0004] In order to solve the technical problems mentioned above, the purpose of this invention is to provide a reverse vacuum preloading reinforcement system and construction method.

[0005] To achieve the objectives of this invention, the technical solution provided by this invention is as follows: First aspect This invention provides a reverse vacuum pre-compression reinforcement system, comprising a reverse vacuum pre-compression unit and a sealed working chamber unit; The reverse vacuum preloading unit includes a bottom horizontal drainage subunit, a vertical drainage subunit, a top sealing subunit, and a monitoring and power supply unit. The bottom horizontal drainage subunit includes a prefabricated horizontal drainage body and a vacuum main pipe. The prefabricated horizontal drainage body is located at the bottom of the soft soil layer to be reinforced. The vacuum main pipe is located inside the prefabricated horizontal drainage body and extends to the connection point of the sealed working chamber unit. The vacuum main pipe includes a permeable inflow section and an impermeable section. The permeable inflow section is located inside and communicates with the prefabricated horizontal drainage body, and the impermeable section is sealed to the quick-connect assembly. The vertical drainage subunit includes multiple drainage plates, the bottom end of which is connected to... The prefabricated horizontal drainage body is pre-tied and fixed to form a grid-like integrated drainage structure to achieve the connection between the vertical drainage channel and the bottom horizontal drainage channel; the top sealing subunit includes a geotextile covering the surface of the treatment area and a geomembrane on it, the geomembrane covers the entire treatment area and its edges are inserted into the soft soil to form a peripheral seal; the monitoring and power supply unit includes a pore water pressure sensor, a mounting platform, a data display, a data acquisition instrument, a power supply system and monitoring instrument cables, the pore water pressure sensor is buried in the soil and connected to the data acquisition instrument via the monitoring instrument cables, the data acquisition instrument is connected to the data display and is installed on the mounting platform together with the power supply system; The sealed working chamber unit includes a sealed working chamber, multiple vacuum pumps, a water pump, and quick-connect components. The sealed working chamber is embedded in the soil to form a closed working space isolated from the outside environment. Its bottom has a barrier structure to prevent external soil and groundwater from entering the chamber. The multiple vacuum pumps are located deep within the sealed working chamber and are sealed to the main vacuum pipe via quick-connect components to apply negative pressure to the prefabricated horizontal drainage body and pump out pore water collected by the drainage board. The water pump is located at the top of the sealed working chamber, with its inlet pipe extending into the bottom of the chamber to drain accumulated water, and its outlet pipe connecting to the drainage area outside the chamber.

[0006] The drainage board is fitted with mud-proof boots at both ends to seal the drainage board ports and prevent mud and sand from entering.

[0007] The prefabricated horizontal drainage body is made of permeable geotextile wrapped with medium-coarse sand or gravel.

[0008] The sealed working chamber is a sealed sleeve that is integrally embedded in the soil, and the bottom of the sleeve is provided with a sealing base plate. The sealed working chamber is a long strip-shaped waterproof trench-type sealed working chamber arranged along the treatment area. The sealed working chamber includes a waterproof lining structure and an openable maintenance cover. Multiple vacuum pumps are installed inside along the length direction according to the treatment area. Each vacuum pump is connected to the vacuum main pipe or multiple vacuum main pipes in sections through quick-connect components.

[0009] The vacuum pump is a jet pump.

[0010] The pore water pressure sensors are multiple and arranged at different depths in the processing area.

[0011] The prefabricated horizontal drainage body and drainage board form a grid-like integrated structure that is guided by a guide frame during the installation process and is sunk into the bottom of the target soft soil layer as a whole by static pressure or vibration methods.

[0012] The power supply system provides AC power to the vacuum pump and the water pump.

[0013] In this process, a second layer of geotextile and a sand cushion layer are laid sequentially on top of the geomembrane, and a load is applied to the sand cushion layer.

[0014] Second aspect This invention also provides a construction method for reverse vacuum preloading reinforcement using the aforementioned reverse vacuum preloading reinforcement system, comprising: 1) sinking a precast horizontal drainage body at the bottom of the soft soil layer in the area to be reinforced, and laying a vacuum main pipe inside the precast horizontal drainage body; 2) inserting multiple drainage boards at designed intervals in the area to be reinforced, and pre-tying the bottom ends of each drainage board to the precast horizontal drainage body to form a grid-like integrated drainage structure; 3) laying geotextile and geomembrane on the ground surface to form a perimeter seal; 4) sinking or constructing a sealed working chamber, installing multiple vacuum pumps at its deep position, and installing a water pump on its upper part; 5) sealingly connecting the vacuum main pipe and the vacuum pumps through quick-connect components; 6) starting the vacuum pump to apply negative pressure to the precast horizontal drainage body and pump out pore water, while simultaneously starting the water pump to remove accumulated water in the sealed working chamber; 7) continuing operation until the soft soil is consolidated to the design requirements.

[0015] Compared with existing technologies, the reverse vacuum preloading reinforcement system and construction method proposed in this invention, by constructing a reverse drainage path between the bottom horizontal drainage structure and the vertical drainage board, forms a short-path, high-efficiency drainage system. This fundamentally overcomes the technical bottlenecks of traditional vacuum preloading technology in deep soft soil foundations, such as long drainage paths and significant deep vacuum attenuation. Through the optimized design of the reverse drainage path, this invention can significantly shorten the drainage distance and improve drainage efficiency, avoiding vacuum energy loss and instability during the consolidation process caused by excessively long drainage channels.

[0016] This invention achieves a high degree of equipment integration by centrally arranging the vacuum pump, water pump, and gas-liquid separation device within a sealed operating chamber unit. This design effectively solves the problems of dispersed equipment, poor sealing, and difficult maintenance in existing reverse vacuum pre-compression systems, significantly improving the system's vacuum stability and operational reliability while reducing maintenance costs. Compared to traditional systems, the sealed operating chamber of this invention provides higher airtightness, ensuring a stable pump operating environment, facilitating inspection and replacement, and further enhancing the overall reliability of the system.

[0017] The core innovation of this invention lies in placing the vacuum pump directly at the bottom of the sealed working chamber and connecting it to the bottom horizontal drainage body via a vacuum main pipe, allowing the negative pressure to act directly on the bottom of the soil to be reinforced. This design significantly reduces vacuum energy loss in the pipeline and overcomes the partial offsetting effect of overlying water pressure on the bottom negative pressure, thereby ensuring that deep soil can obtain near the maximum effective vacuum pressure at the pump end. Through this structural improvement, this invention can achieve the designed negative pressure in deep soil, thereby improving the consolidation rate and degree of consolidation of deep soft soil.

[0018] The integrated monitoring and power supply unit provided by this invention provides power to the components within the auxiliary sleeve unit and can monitor changes in key parameters such as pore water pressure and settlement in real time through matching monitoring equipment. This integrated monitoring and power supply mode ensures the controllability and reliability of the reinforcement process, providing a new approach and reliable technical guarantee for the rapid reinforcement of large-scale, deep soft soil foundations. Attached Figure Description

[0019] Figure 1 A schematic diagram of a reverse vacuum preloading reinforcement system provided by the present invention; Figure 2 A cross-sectional schematic diagram of a reverse vacuum preloading reinforcement system provided by the present invention; Figure 3 A top view schematic diagram of a reverse vacuum preloading reinforcement system provided by the present invention; Figure 4 A first schematic diagram of the connection structure between the prefabricated horizontal drainage body and the drainage board provided by the present invention; Figure 5 A first schematic diagram of the connection structure between the prefabricated horizontal drainage body and the drainage board provided by the present invention; The components include: 1. Precast horizontal drainage body; 2. Vacuum main pipe; 3. Drainage board; 4. Mudproof boot; 5. Vacuum preloading reinforcement area; 6. Geotextile; 7. Geomembrane; 8. Pore water pressure sensor; 9. Mounting platform; 10. Data display; 11. Data acquisition instrument; 12. Power supply system; 13. Monitoring instrument cables; 14. Sealed working chamber; 15. Water pump; 16. Vacuum pump; 17. Quick-connect assembly; 18. Vacuum pump outlet pipe; 19. Water pump inlet pipe; 20. Water pump outlet pipe; 21. Sealed base plate; 22. Top platform; 23. Loading. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-5 The diagram shows the structure of an embodiment provided in this application.

[0022] In the diagram, 1. Precast horizontal drainage body; 2. Vacuum main pipe; 3. Drainage board; 4. Mudproof boot; 5. Vacuum preloading reinforcement area; 6. Geotextile; 7. Geomembrane; 8. Pore water pressure sensor; 9. Mounting platform; 10. Data display; 11. Data acquisition instrument; 12. Power supply system; 13. Monitoring instrument cables; 14. Sealed working chamber; 15. Water pump; 16. Vacuum pump; 17. Quick-connect assembly; 18. Vacuum pump outlet pipe; 19. Water pump inlet pipe; 20. Water pump outlet pipe; 21. Sealed base plate; 22. Top platform; 23. Loading.

[0023] This embodiment provides a reverse vacuum pre-compression reinforcement system that is an auxiliary reverse vacuum pre-compression reinforcement system for a sealed working chamber, including a reverse vacuum pre-compression unit and a sealed working chamber unit; The reverse vacuum preloading unit includes a bottom horizontal drainage subunit, a vertical drainage subunit, a top sealing subunit, and a monitoring and power supply unit. The bottom horizontal drainage subunit includes a prefabricated horizontal drainage body 1 and a vacuum main pipe 2. The prefabricated horizontal drainage body 1 is located at the bottom of the soft soil layer to be reinforced. The vacuum main pipe 2 is located inside the prefabricated horizontal drainage body 1 and extends to the connection point of the sealed working chamber unit. The vacuum main pipe 2 includes a permeable inlet section and an impermeable section. The permeable inlet section is located inside and communicates with the prefabricated horizontal drainage body 1. The impermeable section is sealed to the quick-connect assembly; the vertical drainage subunit includes multiple drainage boards 3, the bottom end of each drainage board 3 is pre-tied and fixed to the prefabricated horizontal drainage body 1 to form a grid-like integrated drainage structure, so as to realize the connection between the vertical drainage channel and the bottom horizontal drainage channel; the top sealing subunit includes a geotextile 6 covering the surface of the treatment area 5 and a geomembrane 7 on it, the geomembrane 7 covers the entire treatment area and its edges are inserted into the soft soil to form a peripheral seal; the monitoring and power supply unit includes pore water pressure The system comprises a sensor 8, a mounting platform 9, a data display 10, a data acquisition instrument 11, a power supply system 12, and monitoring instrument cables 13. The pore water pressure sensor 8 is embedded in the soil and connected to the data acquisition instrument 11 via the monitoring instrument cables 13. The data acquisition instrument 11 is connected to the data display 10 and is mounted on the mounting platform 9 along with the power supply system 12. The sealed working chamber unit includes a sealed working chamber 14, multiple vacuum pumps 16, a water pump 15, and connecting components. The sealed working chamber 14 is disposed in the soil to form an external connection. The sealed working space is isolated by a barrier structure at the bottom to prevent external soil and groundwater from entering the cavity. The multiple vacuum pumps 16 are located deep inside the sealed working cavity 14 and are sealed and connected to the vacuum main pipe 2 via quick-connect assembly 17 to apply negative pressure to the prefabricated horizontal drainage body 1 and pump out the pore water that flows in through the drainage plate 3. The water pump 15 is located at the upper part of the sealed working cavity 14, with its inlet pipe extending into the bottom of the cavity to remove water accumulated inside the cavity and its outlet pipe connected to the drainage area outside the cavity. It should be noted that both ends of the drainage board 3 are fitted with mud boots 4 to seal the drainage board ports and prevent mud and sand from entering.

[0024] It should be noted that the prefabricated horizontal drainage body 1 is made of permeable geotextile wrapped with medium-coarse sand or gravel.

[0025] It should be noted that the sealed working chamber 14 is a sealed sleeve that is integrally embedded in the soil, and a sealing bottom plate 21 is provided at the bottom of the sleeve.

[0026] It should be noted that the sealed working chamber 14 is a long strip-shaped waterproof trench-type sealed working chamber arranged along the processing area. The sealed working chamber includes a waterproof lining structure and an openable maintenance cover. Multiple vacuum pumps 16 are arranged inside along the length direction according to the processing area. Each vacuum pump 16 is connected to the vacuum main pipe 2 or multiple vacuum main pipes 2 in sections through quick-connect assembly 17.

[0027] It should be noted that the vacuum pump 16 is a jet pump.

[0028] It should be noted that there are multiple pore water pressure sensors 8, which are arranged at different depths in the processing area.

[0029] It should be noted that the integrated grid-like structure composed of the prefabricated horizontal drainage body 1 and the drainage board 3 is guided by a guide frame during the installation process and is sunk as a whole into the bottom of the target soft soil layer by static pressure or vibration methods.

[0030] It should be noted that a temporary protective structure may be installed on the part of the vacuum main pipe 2 that extends out of the ground or enters the sealed working chamber 14; during the connection construction, a working pit is dug or an inspection window is set up around the quick-connect component 17 in order to complete the sealed connection between the vacuum main pipe 2 and the quick-connect component 17. After the connection is completed, backfill and compact or close the inspection window.

[0031] It should be noted that the power supply system 12 provides AC power to the vacuum pump 16 and the water pump 15.

[0032] It should be noted that a second layer of geotextile and a sand cushion layer are laid on top of the geomembrane 7, and a load 23 is applied on the sand cushion layer.

[0033] In addition, this embodiment also provides a construction method for reverse vacuum preloading reinforcement using the aforementioned reverse vacuum preloading reinforcement system, including the following: A prefabricated horizontal drainage body 1 is installed at the bottom of the soft soil layer in the area to be reinforced, and a vacuum main pipe 2 is installed inside the prefabricated horizontal drainage body 1. Multiple drainage boards 3 are inserted at the designed intervals in the area to be reinforced, and the bottom ends of each drainage board 3 are pre-tied with the prefabricated horizontal drainage body 1 to form a grid-like integrated drainage structure. Geotextile 6 and geomembrane 7 are laid on the ground surface to form a perimeter seal. A sealed working chamber 14 is installed or constructed, and multiple vacuum pumps 16 are installed at its deep position, and a water pump 15 is installed on its upper part. The vacuum main pipe 2 and the vacuum pump 16 are sealed and connected through a quick-connect assembly 17. The vacuum pump 16 is started to apply negative pressure to the prefabricated horizontal drainage body 1 and pump out pore water. At the same time, the water pump 15 is started to remove the water accumulated in the sealed working chamber 14. The operation continues until the soft soil is consolidated to the design requirements.

[0034] Finally, it should be noted that the above embodiments are merely illustrative and explanatory of the present invention, and are not intended to limit the present invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention.

Claims

1. A reverse vacuum preloading reinforcement system, characterized in that, Includes a reverse vacuum pre-compression unit and a sealed working chamber unit; The reverse vacuum preloading unit includes a bottom horizontal drainage subunit, a vertical drainage subunit, a top sealing subunit, and a monitoring and power supply unit; wherein, the bottom horizontal drainage subunit includes a prefabricated horizontal drainage body (1) and a vacuum main pipe (2); the prefabricated horizontal drainage body (1) is set at the bottom of the soft soil layer to be reinforced; the vacuum main pipe (2) is arranged inside the prefabricated horizontal drainage body (1) and extends to the connection position of the sealed working chamber unit; the vacuum main pipe (2) includes a permeable inflow section and an impermeable section; the permeable inflow section is located inside and communicates with the prefabricated horizontal drainage body (1), and the impermeable section is sealed to the quick-connect assembly (17); the vertical drainage subunit includes multiple drainage plates (3), and the bottom end of each drainage plate (3) is pre-tied to the prefabricated horizontal drainage body (1). A grid-shaped integrated drainage structure is formed to achieve the connection between the vertical drainage channel and the bottom horizontal drainage channel; the top sealing subunit includes a geotextile (6) covering the surface of the treatment area (5) and a geomembrane (7) on it. The geomembrane (7) covers the entire treatment area and its edges are inserted into the soft soil to form a peripheral seal; the monitoring and power supply unit includes a pore water pressure sensor (8), a mounting platform (9), a data display (10), a data acquisition instrument (11), a power supply system (12), and monitoring instrument cables (13). The pore water pressure sensor (8) is buried in the soil and connected to the data acquisition instrument (11) through the monitoring instrument cables (13). The data acquisition instrument (11) is connected to the data display (10) and is installed on the mounting platform (9) together with the power supply system (12); The sealed working chamber unit includes a sealed working chamber (14), multiple vacuum pumps (16), a water pump (15), and a quick-connect assembly (17). The sealed working chamber (14) is set in the soil to form a sealed working space isolated from the outside world. Its bottom is provided with a barrier structure to prevent external soil and groundwater from entering the chamber. The multiple vacuum pumps (16) are set in the deep part of the sealed working chamber (14) and are sealed and connected to the vacuum main pipe (2) through the quick-connect assembly (17) to apply negative pressure to the prefabricated horizontal drainage body (1) and pump out the pore water that flows in through the drainage board (3). The water pump (15) is set in the upper part of the sealed working chamber (14). Its inlet pipe extends into the bottom of the chamber to drain the water accumulated in the chamber, and its outlet pipe is connected to the drainage area outside the chamber.

2. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that: The drainage board (3) is fitted with mud boots (4) at both ends to seal the drainage board ports and prevent mud and sand from entering.

3. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that, The prefabricated horizontal drainage body (1) is made of medium-coarse sand or gravel wrapped with permeable geotextile.

4. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that, The sealed working cavity (14) is a sealed sleeve that is integrally embedded in the soil, and a sealing bottom plate (21) is provided at the bottom of the sleeve. The sealed working chamber (14) is a long strip-shaped waterproof trench-type sealed working chamber arranged along the treatment area. The sealed working chamber includes a waterproof lining structure and an openable maintenance cover. Multiple vacuum pumps (16) are arranged inside along the length direction according to the treatment area. Each vacuum pump (16) is connected to the vacuum main pipe (2) or multiple vacuum main pipes (2) in sections through quick-connect assembly (17).

5. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that: The vacuum pump (16) is a jet pump.

6. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that: There are multiple pore water pressure sensors (8) arranged at different depths in the processing area.

7. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that, The prefabricated horizontal drainage body (1) and drainage board (3) form a grid-like integrated structure that is guided by a guide frame during the sinking process and is sunk into the bottom of the target soft soil layer as a whole by static pressure or vibration method.

8. The reverse vacuum preloading reinforcement system according to claim 1, characterized in that, The power supply system (12) provides AC power to the vacuum pump (16) and the water pump (15).

9. A reverse vacuum preloading reinforcement system according to claim 1, characterized in that, A second layer of geotextile and a sand cushion layer are laid on top of the geomembrane (7), and a load (23) is applied on the sand cushion layer.

10. A construction method for reverse vacuum preloading reinforcement using the reverse vacuum preloading reinforcement system as described in any one of claims 1-9, characterized in that, include: 1) A prefabricated horizontal drainage body (1) is installed at the bottom of the soft soil layer in the area to be reinforced, and a vacuum main pipe (2) is installed in the prefabricated horizontal drainage body (1). 2) Insert multiple drainage boards (3) at the designed spacing in the area to be reinforced, and bind the bottom of each drainage board (3) to the prefabricated horizontal drainage body (1) to form a grid-like integrated drainage structure. 3) Lay geotextile (6) and geomembrane (7) on the ground surface to form a perimeter seal; 4) Set up or construct a sealed working chamber (14), install multiple vacuum pumps (16) at its deep part, and install a water pump (15) on its upper part. 5) Connect the vacuum main pipe (2) to the vacuum pump (16) in a sealed manner using the quick-connect assembly (17); 6) Start the vacuum pump (16) to apply negative pressure to the prefabricated horizontal drainage body (1) and pump out the pore water. At the same time, start the water pump (15) to remove the water accumulated in the sealed working chamber (14). 7) Continue running until the soft soil is consolidated to the design requirements.

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