A volume-compensated segmented airbag method for controlling deformation of a surrounding ground layer in vacuum preloading

Abstract

The present application relates to a kind of control vacuum preloading surrounding strata deformation volume compensation type segmented air bag method, first in vacuum preloading area sealing ditch outside setting segmented air bag, anchor to deep soil layer in fixed, upper end is connected to inflation pipe, inflation pipe is connected to inflation pump, setting depth is consistent with drain board depth;Then vacuum preloading area starts to be evacuated, after vacuumizing, start inflation pump, according to the lateral deformation value of different depth soil body, fill corresponding different volume of air into air bag, air bag expands and extrudes soil body, the volume of air bag expansion offsets the lateral deformation of soil body, to reduce the influence on surrounding environment;Finally, inject flow state solidified soil into segmented air bag, remove inflation and grouting device after reaching strength, segmented air bag remains in strata.Compared with prior art, the method of the present application is economical and reasonable, high processing efficiency, and is suitable for the protection of surrounding environment when vacuum preloading soft soil foundation is treated.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to a volume-compensated segmented airbag method for controlling the deformation of the strata surrounding vacuum preloading. Background Technology

[0002] Deep soft soil is widely distributed in the southeastern coastal areas of my country. Due to the characteristics of soft soil such as high compressibility, heterogeneity and low shear strength, building structures directly on it are prone to uneven settlement, which can lead to damage to the superstructure and endanger building safety.

[0003] Currently, the main methods for treating soft soil foundations include sand well method, vacuum preloading method, surcharge method, and combined vacuum preloading and surcharge method. The purpose of all these methods is to drain and consolidate the soft soil foundation. The most common method is vacuum preloading, which involves installing plastic drainage boards within the soft soil foundation and connecting them with drainage pipes to form a drainage network. A sand cushion layer or geotextile is then laid on the drainage network, followed by a sealing membrane to isolate the air. A vacuum pump is connected to the drainage pipes to apply vacuum loading, extracting air and pore water from the soft soil, thereby achieving drainage and consolidation of the soft soil.

[0004] Vacuum preloading uses vacuum suction to extract gas and pore water from soft soil. As a result, the soft soil gradually moves closer to the drainage board during this process, and the soil undergoes lateral displacement. The lateral displacement gradually decreases as the distance between the soil and the drainage board increases. However, excessive lateral displacement often occurs at the edge of the vacuum preloading area, leading to soil cracking, which seriously affects the surrounding environment and buildings.

[0005] Currently, methods for controlling lateral displacement caused by vacuum preloading mainly include isolation walls and combined loading. Isolation walls mainly include pile walls and cement-soil mixing walls. Their disadvantages are: the protective effect of isolation walls is greatly affected by the overall structural stiffness and self-weight, and construction costs are often high to achieve a good effect in limiting lateral deformation; vacuum combined loading preloading limits lateral deformation by offsetting, to some extent, the lateral deformation outside the reinforced zone caused by the loading with the lateral deformation inside the reinforced zone caused by the vacuum loading. Its disadvantages are: higher construction difficulty, higher cost, and the fact that the loading is not designed with the purpose of limiting lateral deformation.

[0006] CN106284277A discloses a method for reinforcing a foundation using a combination of airbag compression drainage and vacuum preloading. A sand cushion layer is laid on the foundation, and drainage boards are driven into the foundation, with the upper end connected to a drainage pipe. The drainage pipe is connected to a vacuum pump. Airbags are driven into the foundation, with the upper end connected to an inflation pipe. The inflation pipe is connected to an inflation pump. The vacuum pump is started to drain water from the drainage boards, and the inflation pump is started to inflate the airbags and compress the soil. The soil consolidates under the combined pressure of the vacuum and the airbags. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies by providing a volume-compensating segmented airbag method for controlling the deformation of strata surrounding vacuum preloading. Addressing the high carbon emissions of various foundation treatment methods, this invention, based on the vacuum preloading method and the principle of providing positive pressure to the soil, can provide different positive pressures according to depth changes during vacuum preloading. Simultaneously, it utilizes the variable volume of the airbags to compensate for and limit lateral deformation of the soil, offering good economic efficiency and broad application prospects. This method is the opposite of the airbag compression drainage combined with vacuum preloading foundation reinforcement method disclosed in CN106284277A. This invention's volume-compensating segmented airbag method for controlling the deformation of strata surrounding vacuum preloading does not promote soil consolidation, but rather increases the volume of the airbags by inflating them to compensate for the lateral deformation caused by vacuum preloading. Smaller lateral deformation requires a smaller airbag volume, while larger lateral deformation requires a larger volume to be compensated by the airbags. Anchor heads are installed at the bottom of the airbags to fix them at a certain depth. After the airbags are used up, they are filled with fluid soil to compact them.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] The purpose of this invention is to provide a volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading, used to limit the lateral displacement of soil outside the vacuum preloading zone. This method includes the following steps:

[0010] S1. Install segmented airbags outside the sealing trench in the vacuum preloading area. Each segmented airbag includes multiple inflatable chambers. The bottom of each segmented airbag is anchored to the deep soil layer for fixation. The upper end is connected to an inflation hose, which is connected to an air pump. The installation depth is consistent with the depth of the plastic drainage board.

[0011] S2. A vacuum pump is used to evacuate the vacuum preloading area. After evacuation, the vacuum preloading process is carried out. The air pump is started, and air of different volumes is injected into each air chamber of the segmented airbag according to the lateral deformation value of the soil at different depths. The segmented airbags expand and squeeze the soil. The volume of the segmented airbags is used to offset the lateral deformation of the soil, thereby reducing the impact on the surrounding environment.

[0012] S3. After the vacuum preloading process is completed, fluidized solidified soil is injected into the segmented airbags through the central grouting pipe. After the strength is reached, the inflation and grouting devices are removed, and the segmented airbags remain in the stratum.

[0013] Furthermore, the method also includes the following step S4, which is performed before step S1: installing plastic drainage boards, laying geotextiles and sealing membranes in the vacuum preloading area as required, and connecting the drainage branch pipes, plastic drainage boards and drainage main pipes, and connecting the connecting pipes to the vacuum pump.

[0014] Furthermore, the method also includes the following step S5, which is performed before step S4: laying a sand cushion layer or woven fabric on the foundation on a leveled site.

[0015] Furthermore, no special treatment is required in the vacuum pre-compression area, and the segmented airbags are evenly arranged on the outside of the sealing groove at a certain interval.

[0016] Furthermore, the bottom of the central grouting pipe is provided with an anchor head, which can fix the segmented airbags and effectively prevent the airbags from being squeezed upwards as a whole after inflation.

[0017] Furthermore, the segmented airbag is divided into multiple inflatable chambers from top to bottom. Each inflatable chamber is connected in series through a central grouting pipe and driven into the stratum to a designated depth to serve as a fixation device. Each inflatable chamber is equipped with an inflation hose, and the inflation pressure of each inflatable chamber is different, which can realize graded pressurization according to depth.

[0018] Furthermore, the volume of each inflatable chamber decreases sequentially from top to bottom, with the uppermost inflatable chamber in the segmented airbag having the largest volume.

[0019] Furthermore, the length, spacing, and number of inflatable chambers of the segmented airbags can be determined based on the depth of the drainage board installation and the type of building that needs to be protected outside the vacuum pre-compression area, providing considerable flexibility.

[0020] Further, step S2 is performed in the vacuum drainage system and the airbag pressurization system, which includes: a plastic drainage board, a drainage branch pipe, a drainage main pipe, an air pump, segmented airbags, an inflation hose, an inflation main pipe, a vacuum pump, and a connecting pipe; the drainage branch pipe and the plastic drainage board are connected to the drainage main pipe, the connecting pipe is connected to the vacuum pump, the segmented airbags are connected to the inflation hose, and the inflation hose is connected to the air pump through the inflation main pipe.

[0021] Furthermore, the drainage branch pipes and drainage main pipes are perpendicular to each other and are arranged in parallel. The spacing between the branch pipes is 0.5m to 1.2m, and the spacing between the drainage main pipes is 20m to 30m. All drainage main pipes converge into the connecting pipe and are connected to the vacuum pump.

[0022] Furthermore, the horizontal cross-section of the inflatable chamber can be circular, elliptical, rectangular, rhomboid, or other shapes, all of which are within the scope of protection of this patent.

[0023] Furthermore, the plastic drainage board is a vertical drainage board.

[0024] More preferably, a circular shape is preferred.

[0025] Furthermore, wear-resistant rubber is preferably selected as the material for the segmented airbag.

[0026] Furthermore, the method further includes the following step S5, which is performed after step S4 and before step S1: installing lateral oblique tubes on both sides of the preset position of the segmented airbag.

[0027] Furthermore, the fluidized solidified soil can be replaced by other slurries that combine fluidity and long-term strength.

[0028] Furthermore, during the vacuum preloading process, it is essential to monitor data such as vacuum level, settlement, pore water pressure, and lateral displacement of the soil. Vacuuming should be stopped when the design requirements are met.

[0029] Furthermore, during the injection of fluidized solidified soil, the volume and pressure of compressed air inside the airbag must be strictly controlled to prevent excessive lateral deformation caused by sudden degassing. After filling the airbag, it should be cured for about 7 days.

[0030] Furthermore, for different projects, the actual parameters, including airbag radius, drilling location, and pressure, need to be calculated and determined.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The volume-compensated segmented airbag method provided by this technical solution, which controls the deformation of the surrounding strata by vacuum preloading through volume-compensated segmented airbags, uses airbag pressurization. The airbag pressure can be precisely adjusted according to the inclination data. The airbag is divided into several inflatable chambers, and different pressures can be applied according to different depths, which overcomes the defect that the traditional isolation wall cannot be adjusted after it is built.

[0033] (2) The volume-compensated segmented airbag method provided by this technical solution, which controls the deformation of the surrounding strata by vacuum preloading through volume-compensated segmented airbags, adopts the airbag pressurization method. The construction method is relatively simple, has no impact on the surrounding environment, has low construction cost, and is highly economical. It provides a new, efficient, precise, environmentally friendly and economical method for controlling the lateral deformation of soil. While accurately controlling the lateral displacement of soil, it will not have any negative impact on the surrounding environment.

[0034] (3) The volume-compensated segmented airbag method provided by this technical solution controls the deformation of the surrounding strata by using volume-compensated segmented airbags to control vacuum preloading. After the vacuum preloading process is completed, the airbags are stopped from being pressurized and grout is injected directly into the airbags. Compared with the conventional method of setting isolation piles, this method reduces construction costs and improves economic benefits. Attached Figure Description

[0035] Figure 1 This is a process flow diagram of the volume-compensated segmented airbag method of the present invention, which controls the deformation of the surrounding strata by vacuum preloading through volume-compensated segmented airbags.

[0036] Figure 2 This is a cross-sectional structural schematic diagram of the volume-compensated segmented airbag method for controlling the deformation of the surrounding strata by vacuum preloading in an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram of the planar structure of the volume-compensated segmented airbag method for controlling the deformation of the surrounding strata by vacuum preloading in an embodiment of the present invention.

[0038] The numbers in the diagram are as follows:

[0039] 1. Plastic drainage board, 2. Sealing trench, 3. Geotextile, 4. Sealing membrane, 5. Drainage branch pipe, 6. Drainage main pipe, 7. Inclinometer pipe, 8. Air pump, 9. Segmented airbag, 10. Inflatable hose, 11. Inflatable main pipe, 12. Vacuum pump, 13. Central grouting pipe, 14. Connecting pipe. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Unless otherwise specified in this technical solution, features such as component models, material names, and connection structures are considered common technical features disclosed in the prior art. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading, the method comprising the following steps:

[0042] S1. Install segmented airbags 9 outside the vacuum preloading area sealing trench 2. The segmented airbags 9 include multiple inflatable chambers. The bottom of the segmented airbags 9 is anchored to the deep soil layer for fixation. The upper end is connected to the inflation hose 10. The inflation hose 10 is connected to the inflation pump 8. The installation depth is consistent with the depth of the plastic drainage board.

[0043] S2. Vacuum pump 12 is used to evacuate the vacuum preloading area. After evacuation, the vacuum preloading process is carried out. The air pump 8 is started. According to the lateral deformation value of the soil at different depths, air of different volumes is injected into each air chamber of the segmented airbag 9. The segmented airbag 9 expands and squeezes the soil. The expansion volume of the segmented airbag 9 is used to offset the lateral deformation of the soil, thereby reducing the impact on the surrounding environment.

[0044] S3. After the vacuum preloading process is completed, fluidized solidified soil is injected into the segmented airbags 9 through the central grouting pipe 13. After the strength is reached, the inflation and grouting devices are removed, and the segmented airbags 9 remain in the stratum.

[0045] like Figures 1-3As shown, this embodiment provides a volume-compensated segmented airbag method for controlling the deformation of the strata surrounding vacuum preloading, including the following steps:

[0046] This embodiment provides a volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading, including the following steps:

[0047] S1. Collect soil samples from the reinforced area on site, and determine its unit weight, initial void ratio, compression index, effective stress friction angle, cohesion, and e-lnp curve. Use the above data to calculate the lateral displacement change of the soil.

[0048] S2. Based on the calculation results of step S1 and in conjunction with the installation depth of the plastic drainage board, determine the length of the central grouting pipe, the size and quantity of the airbag inflation chamber, the length of the segmented airbag rod 9 should be greater than the installation length of the drainage board, the shape of the airbag should be circular, and the material should be wear-resistant rubber.

[0049] S3. Level the reinforced area and surrounding ground, and lay woven fabric within the reinforced area.

[0050] S4. Install vertical plastic drainage boards using a jackhammer. The installation depth must meet design requirements, with the top of the plastic drainage board protruding 30cm-50cm above the ground. Connect the exposed plastic drainage boards to drainage branch pipes 5, which then converge into the main drainage pipe 6 to form a drainage network. All drainage main pipes 6 converge into drainage connection pipe 14 and are connected to vacuum pump 12. Vacuum pump 12 is then connected to the pump room. Every 1000m... 2 ~1500m 2 Set up a vacuum pump 12, and the spacing of the drainage branch pipes 5 should be twice the spacing of the plastic drainage boards. Figure 2 , 3 As shown, inclinometer holes are drilled outside the reserved area of ​​sealing trench 2 to install inclinometer tubes 7. It is necessary to ensure that there are inclinometer tubes on both sides of the segmented airbag 9 position, so as to facilitate monitoring of the lateral displacement of the soil outside the reinforced area after vacuum loading and airbag pressurization, and timely adjustment of airbag pressure. The depth of the inclinometer hole is determined according to the depth of the plastic drainage board.

[0051] S5. Excavate sealing trench 2. The depth of sealing trench 2 shall not be less than 1.5m and must penetrate the shallow permeable layer below the ground surface. In the reinforcement area, first lay non-woven geotextile 3 and then lay sealing membrane 4. The sealing membrane 4 shall be buried 3m to 4m into sealing trench 2 on each side of the reinforcement area. Sealing trench 2 shall be backfilled with clay and compacted to prevent air leakage during vacuum loading.

[0052] S6. Drill holes for segmented airbags 9 at a certain distance from the outside of the sealing trench 2. The hole diameter should be slightly larger than the outer diameter of the airbag before inflation to prevent the airbag from being punctured when placing the segmented airbags 9. Insert the segmented airbags 9 into the holes. An anchor head is provided at the bottom of the central grouting pipe 13 to prevent the segmented airbags 9 from being squeezed upwards due to the expansion of the airbag volume after pressurization. Each inflation chamber is connected to an inflation hose 10, the other end of which is connected to the main inflation pipe 11. The main inflation pipe 11 is connected to the inflation pump. The inflation hoses 10 of inflation chambers of different depths are connected to different main inflation pipes 11 to facilitate the application of different pressures.

[0053] S7. After vacuum loading for 1-2 hours, turn on the vacuum pump to inflate the airbag. The vacuum pressure is transmitted from the main drainage pipe 6 to the branch drainage pipe 5, then to the plastic drainage board 1, and finally diffuses into the foundation. The air pressure is transmitted through the inflation main pipe 11 to the inflation hose 10, and then to the airbag. The expansion of the airbag transmits the pressure to the surrounding soil. The magnitude of the airbag pressure is calculated based on the theory of linear attenuation of the external soil pressure in the vertical direction.

[0054] S8. During the vacuum preloading process, the lateral displacement of the soil on both sides of the segmented airbag 9 should be measured at regular intervals as required. If the lateral displacement of the soil outside the reinforcement is too large, the air pressure should be increased to further limit the lateral displacement. If the lateral displacement of the soil between the reinforcement area and the segmented airbag 9 is too large, the air pressure should be reduced to prevent the soil from becoming unstable.

[0055] S9. Conduct on-site data monitoring, including vacuum level, surface settlement, pore water pressure, deep lateral displacement, and external soil pressure. When the settlement stabilizes and meets the design requirements, take soil samples for analysis. If the design requirements for strength and moisture content are met, the vacuum process can be stopped.

[0056] S10. After completion, remove the vacuum preloading system, stop the airbag pressurization system and inject fluidized solidified soil into the airbag. After the fluidized solidified soil reaches the required strength, remove the inflation device and grouting device, leaving the segmented airbag 9 in the stratum.

[0057] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading, used to limit the lateral displacement of soil outside the vacuum preloading zone, characterized in that, Includes the following steps: S1. Install segmented airbags (9) outside the vacuum pre-compression area sealing trench (2). The segmented airbags (9) include multiple air chambers. The bottom of the segmented airbags (9) is anchored to the deep soil layer for fixation. The upper end is connected to the air hose (10). The air hose (10) is connected to the air pump (8). The installation depth is consistent with the depth of the plastic drainage board. S2. Vacuum pump (12) is used to evacuate the vacuum preloading area. After evacuation, vacuum preloading process is carried out. Air pump (8) is started. Air of different volumes is filled into each air chamber of segmented airbag (9) according to the lateral deformation value of soil at different depths. The segmented airbag (9) expands and squeezes the soil. The volume of expansion of segmented airbag (9) offsets the lateral deformation of the soil, thereby reducing the impact on the surrounding environment. S3. After the vacuum preloading process is completed, fluidized solidified soil is injected into the segmented airbags (9) through the central grouting pipe (13). After the strength is reached, the inflation and grouting device is removed, and the segmented airbags (9) remain in the stratum. The procedure also includes the following steps: installing plastic drainage boards, laying geotextile (3) and sealing membrane (4) in the vacuum preloading area, and connecting drainage branch pipe (5), plastic drainage board (1) to drainage main pipe (6), and connecting pipe (14) to vacuum pump (12).

2. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, It also includes the following steps: On a leveled site, lay a sand cushion or woven fabric on the foundation.

3. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, The segmented airbags (9) are evenly arranged on the outside of the sealing groove (2).

4. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, The bottom of the central grouting pipe (13) is provided with an anchor head.

5. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, The segmented airbag (9) is divided into multiple inflatable chambers from top to bottom. Each inflatable chamber is connected in series through the central grouting pipe (13) and injected into the stratum to a specified depth. Each inflatable chamber is equipped with an inflatable hose (10), and the inflation pressure of each inflatable chamber is different.

6. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 5, characterized in that, The volume of each inflatable chamber decreases from top to bottom, with the uppermost inflatable chamber in the segmented airbag (9) having the largest volume.

7. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, Step S2 is performed in the vacuum drainage system and the airbag pressurization system, which includes: a plastic drainage plate (1), a drainage branch pipe (5), a drainage main pipe (6), an air pump (8), a segmented airbag (9), an air hose (10), an air main pipe (11), a vacuum pump (12), and a connecting pipe (14). The drainage branch pipe (5), the plastic drainage board (1) are connected to the drainage main pipe (6), the connecting pipe (14) is connected to the vacuum pump (12), the segmented airbag is connected to the inflation hose (10), and the inflation hose (10) is connected to the inflation pump through the inflation main pipe (11).

8. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, The horizontal cross-section of the inflatable chamber is circular, elliptical, rectangular, or rhomboid.

9. The volume-compensated segmented airbag method for controlling the deformation of strata surrounding vacuum preloading according to claim 1, characterized in that, It also includes the following steps: Side-sloping tubes (7) are installed on both sides of the preset position of the segmented airbag.

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