Vacuum assisted composite rigid drainage device and method of drainage

Abstract

The present application relates to the ground treatment technology, especially to the weak ground treatment technology with high water content, in particular to a vacuum-assisted composite rigid drainage device and a drainage method, which solves the problem of poor bearing capacity improvement effect of the weak ground with high water content after dehydration in the prior art, and the need for secondary reinforcement treatment, and realizes rapid dehydration through the rigid vertical drainage assembly, the rigid horizontal drainage assembly and the vacuum-assisted device. After dehydration, the vertical drainage unit is left in the soil to directly improve the bearing capacity of the soil body for the large machinery to enter. The rigid vertical drainage assembly comprises a plurality of vertical drainage units inserted into the weak ground, the vertical drainage unit comprises a rigid plate-shaped part, the plate surface of the rigid plate-shaped part is provided with vertically distributed drainage ropes, and the outside is wrapped with a water-permeable geotextile; the rigid horizontal drainage assembly comprises a rigid drainage support layer covering the surface of the weak ground, the upper surface of the rigid drainage support layer is provided with a flexible sealing layer, and the flexible sealing layer is provided with a drainage port.

Description

Technical Field

[0001] This invention relates to foundation treatment technology, particularly to the field of soft foundation treatment technology with high water content, and specifically to a vacuum-assisted composite rigid drainage device and drainage method. Background Technology

[0002] Currently in China, numerous abandoned reservoirs and water storage ponds urgently require repair and reinforcement. Deposits such as sand and clay accumulated in these ponds may overflow during heavy rainfall due to aging infrastructure, triggering mudslides and other disasters, thus threatening the safety of the reservoirs. However, during the repair and dredging process, the extremely high water content of the soil in the water storage ponds and their poor foundation bearing capacity make it difficult to transport heavy machinery and vehicles to the site. Therefore, it is essential to improve the soft foundation with high surface water content.

[0003] Existing technologies for improving ordinary surface soft foundations mainly include cement consolidation (surface improvement method), sand pile compaction (densification reinforcement method), and sand core drainage (compaction drainage method). These methods suffer from high costs and pollution due to the large amount of cement or sand required. Furthermore, the supply of such materials in specific areas presents implementation challenges. The combined use of vertical drainage boards (PVD) and vacuum consolidation has become one of the most effective ground improvement technologies. This technology inserts PVD into deep soil layers to shorten the drainage path, while vacuum assistance accelerates the horizontal flow of pore water into the PVD, achieving rapid dehydration to minimize internal pore water pressure, improve soil shear strength, and thus rapidly increase bearing capacity. However, most commercially available PVD is supplied in roll form, and its structure typically consists only of a geosynthetic core serving as a drainage channel and a permeable geotextile wrapped around it. Therefore, in actual construction, PVD usually requires the use of sleeves or equipment with sufficient rigidity to be pressed into the ground, and this process usually relies on large construction machinery.

[0004] However, the above-mentioned treatment methods have poor load-bearing capacity improvement effects. If large machinery is allowed to enter, secondary reinforcement treatment with cement, lime, sand, and gravel is necessary. Therefore, there is an urgent need for a technology that can simultaneously improve the load-bearing capacity of soft foundations with high water content by dehydration. Summary of the Invention

[0005] This invention provides a vacuum-assisted composite rigid drainage device and drainage method, which solves the problem in the prior art that the bearing capacity improvement effect after dewatering of soft foundations with high water content is poor and secondary reinforcement treatment is required. The device achieves rapid dewatering through rigid vertical drainage components, rigid horizontal drainage components and vacuum-assisted device. The vertical drainage unit is left in the soil to directly improve the bearing capacity and allows large machinery to enter.

[0006] This invention is achieved through the following technical solution: A vacuum-assisted composite rigid drainage device includes, A rigid vertical drainage assembly includes several vertical drainage units inserted vertically into a soft foundation. Each vertical drainage unit includes a rigid plate-like component, and vertically distributed drainage ropes are provided on the surface of the rigid plate-like component. A rigid horizontal drainage assembly includes a rigid drainage support layer covering a soft foundation surface, a flexible sealing layer on top of the rigid drainage support layer, and a drainage outlet on the flexible sealing layer. A vacuum-assisted device, which is connected to the drain outlet via a drain pipe.

[0007] Furthermore, the drainage rope is an ethylene-propylene copolymer rope.

[0008] Furthermore, the outer side of the rigid plate-shaped member is also provided with a permeable geotextile that wraps around the drainage rope.

[0009] Furthermore, the flexible sealing layer is a plastic film.

[0010] Furthermore, the rigid drainage support layer consists of a bamboo frame, a geogrid, and a plastic mesh, arranged from bottom to top.

[0011] Furthermore, the drainage rope is wound around the rigid plate in the vertical direction, and the drainage rope is fixed to the rigid plate by multiple straps.

[0012] Furthermore, the vacuum assist device includes a vacuum pump, a filter, and a water tank.

[0013] Furthermore, the vertical drainage units are arranged in an array within the soft foundation.

[0014] A vacuum-assisted composite rigid drainage method, employing the aforementioned vacuum-assisted composite rigid drainage device to drain soft foundations with high water content, includes the following steps: S10. First, prepare several vertical drainage units, prepare rigid plate-shaped parts, wrap the drainage rope around the outer surface of the rigid plate-shaped parts and fix it, and then wrap a layer of permeable geotextile around the outside of the rigid plate-shaped parts. Workers manually insert vertical drainage units vertically into the soft mud in the weak foundation treatment area, so that several vertical drainage units are distributed in an array in the weak foundation. S20. On the surface of the soft foundation treatment area, bamboo board frame, geogrid, plastic mesh and plastic film are covered from bottom to top. The bamboo board frame, geogrid and plastic mesh form a rigid drainage support layer, and the plastic film forms a flexible sealing layer. A drainage outlet is provided in the center of the plastic film, and the edges of the plastic film are compacted and sealed with sludge to ensure airtightness under vacuum conditions. S30. Establish a vacuum assist device, and connect the vacuum assist device to the drain outlet through a drain pipe; S40. Start the vacuum auxiliary device to apply negative pressure to the soft foundation treatment area. The water in the soil is extracted through the rigid vertical drainage component and the rigid horizontal drainage component to achieve soil dehydration. S50. During the drainage process, record the dehydration time and cumulative drainage volume, and calculate the average soil moisture content based on the measured cumulative drainage volume. When the average moisture content is close to the soil liquid limit, stop the vacuum-assisted device. S60. After the soil dewatering is completed, an on-site plate load test is conducted on the soft foundation treatment area to evaluate the bearing capacity of the soil after dewatering. S70. Once the load-bearing capacity meets the requirements, retract the rigid horizontal drainage component to allow the mechanical equipment to enter for subsequent operations.

[0015] The beneficial effects achieved by this invention compared with the prior art are as follows: 1. The vacuum-assisted composite rigid drainage device of the present invention mainly includes a rigid vertical drainage component, a rigid horizontal drainage component, and a vacuum auxiliary device. The rigid vertical drainage component includes several vertical drainage units inserted into the soft foundation. Rapid dewatering is achieved through the rigid vertical drainage component, the rigid horizontal drainage component, and the vacuum auxiliary device. The vertical drainage units are left in the soil to directly improve the soil bearing capacity, allowing large machinery to enter. At the same time, drainage and bearing capacity are improved. The structure is simple and can be manually installed without mechanical assistance. The vacuum-assisted composite rigid drainage method described in this invention enables simultaneous drainage and bearing capacity enhancement for soft foundations with high water content, overcoming the shortcomings of existing technologies where the bearing capacity enhancement effect after dehydration of soft foundations with high water content is poor and secondary reinforcement treatment is required. 2. This invention can reduce the soil moisture content by about 20% to 40% after 4 hours of dehydration, thus achieving rapid soil dehydration; 3. After the dehydration operation is completed, the vertical drainage unit is left in the soil. The rigid plate-shaped component can generate a large friction force with the dehydrated soil, so that after 4 hours of dehydration, it can achieve the load-bearing capacity of a 5-ton hydraulic excavator, meeting the requirements for construction machinery to enter the site. 4. The drainage rope is made of ethylene propylene copolymer rope. The rigid drainage support layer consists of bamboo frame, geogrid and plastic mesh from bottom to top, which can effectively save economic costs. The materials are strong and durable. The drainage support layer can be recycled and reused after the operation is completed. 5. The device and method described in this invention are applicable to various water-bearing soil treatment scenarios, such as dewatering and improving the bottom sediment of hydraulic structures like reservoirs and sedimentation tanks to enhance their bearing capacity and stability; reinforcement and treatment of silt in rivers and lakes, as well as soft soil foundations, to improve soil structure and engineering mechanical properties; optimization of farmland drainage systems and improvement of wetland soil to reduce soil moisture content and improve its utilization performance; and emergency rescue projects and temporary road paving scenarios, where rapid dewatering treatment improves the foundation bearing capacity to meet short-term traffic and construction needs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the vacuum-assisted composite rigid drainage device of the present invention; Figure 2 This is a schematic diagram showing the connection between the rigid plate-like member and the drainage rope described in this invention; Figure 3 This is a top sectional view of the vertical drainage unit described in this invention; Figure 4 This is a schematic diagram of the rigid drainage support layer described in this invention; Figure 5 This is a schematic diagram of the operation of the vacuum-assisted composite rigid drainage device described in this invention; In the diagram: 1. Vertical drainage unit, 11. Rigid plate, 12. Drainage rope, 13. Permeable geotextile, 2. Rigid drainage support layer, 21. Bamboo frame, 22. Geogrid, 23. Plastic mesh, 3. Plastic film, 31. Drainage outlet, 4. Vacuum pump, 5. Filter, 6. Water tank. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0018] In the description of the invention, it should be understood that the terms "front", "rear", "up", "down", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention. Example 1

[0019] Taking the drainage operation of a soft foundation with high water content around a reservoir as an example, where the soil moisture content of the soft foundation is above 110%, this embodiment discloses a vacuum-assisted composite rigid drainage device to simultaneously enhance the bearing capacity during drainage. Figure 1 As shown, it mainly includes a rigid vertical drainage assembly, a rigid horizontal drainage assembly, and a vacuum auxiliary device.

[0020] The rigid vertical drainage assembly includes several vertical drainage units 1 vertically inserted into the soft foundation, such as... Figure 2-3 As shown, each vertical drainage unit 1 includes a rigid plate-like component 11 and a drainage rope 12. The rigid plate-like component 11 is made of hard bamboo, with a length of 60cm-90cm, a width of 5cm, and a thickness of 1cm. The drainage rope 12 is made of ethylene propylene copolymer rope (also called KP rope) with a diameter of 9mm. This type of rope is characterized by being made by twisting and gathering several filamentous matrix fibers together. Ethylene propylene copolymer has good hydrophobicity. Since this is a conventional technical method, it will not be described in detail here. The drainage rope 12 is wound around the rigid plate-like component 11 in the vertical direction and is fixed to the rigid plate-like component 11 by multiple binding straps. A permeable geotextile 13 is also provided on the outside of the rigid plate-like component 11 to wrap the drainage rope 12. The bamboo boards can be manually inserted into the soft mud, providing sufficient rigidity and strength for the dewatering device. The KP ropes, together with the bamboo boards, form vertical drainage channels. Under negative pressure, soil moisture is drained upwards through these channels. The permeable geotextile 13 primarily filters soil particles, preventing clogging of the KP ropes. Several vertical drainage units 1 are arranged in an array within the soft foundation treatment area, for example, in a houndstooth or grid pattern. They are arranged to the required length and spacing according to construction requirements, with spacing generally controlled at 15-30cm. The overall size depends on the area to be treated.

[0021] like Figure 4As shown, the rigid horizontal drainage assembly mainly includes a rigid drainage support layer 2 and a flexible sealing layer. The rigid drainage support layer 2 covers the surface of the soft foundation treatment area, thus covering the rigid vertical drainage assembly. From bottom to top, the rigid drainage support layer 2 consists of a bamboo frame 21, a geogrid 22, and a plastic mesh 23, with the bamboo frame 21 at the bottom, constructed from bamboo strips. The flexible sealing layer is a plastic film 3, which covers the surface of the rigid drainage support layer 2. The bamboo frame 21, geogrid 22, and plastic mesh 23 replace the sand cushion layer, forming a horizontal drainage channel under vacuum negative pressure conditions and are recyclable. The plastic film 3 maintains the vacuum sealing performance of the system, with its edges sealed with compacted clay to ensure airtightness under vacuum conditions. A drain outlet 31 is located at the center of the uppermost plastic film 3, and then connected to the vacuum auxiliary device via a drainage hose.

[0022] The vacuum-assisted device includes a vacuum pump 4, a water tank 6, and a filter 5 connected in sequence. The inlet of the filter 5 is connected to the drain outlet 31 via a drain hose. The water tank 6 is a 15 L water container, the filter 5 is 4 L, and the vacuum pump is a GM-20D type vacuum pump with an ultimate vacuum of 0.095 MPa, a flow rate of 20 / 24 L min⁻¹, and AC 100 V. When the vacuum pump 4 draws a vacuum, the water in the soil passes through a rigid vertical drainage component, a rigid horizontal drainage component, and then is filtered by the filter 5 before finally entering the water tank 6.

[0023] The specific working process of the vacuum-assisted composite rigid drainage device described in this embodiment is as follows: When drainage is required for the weak foundation, vacuum pump 4 is activated. The vacuum-assisted device applies negative pressure to the weak foundation treatment area, creating a negative pressure vacuum within the rigid horizontal drainage assembly. Water in the soil preferentially enters the KP rope. The KP rope and bamboo boards together form a vertical drainage channel, allowing water in the soil to be extracted through the rigid vertical and rigid horizontal drainage assemblies, filtered, and collected in the water tank 6, thus achieving soil dehydration. After dehydration, the vertical drainage unit remains in the soil. The arrayed bamboo boards, under the frictional force between the soil and the bamboo, directly increase the bearing capacity, allowing large machinery to enter.

[0024] The vacuum-assisted composite rigid drainage device described in this embodiment achieves rapid dewatering through a rigid vertical drainage component, a rigid horizontal drainage component, and a vacuum-assisted device. The vertical drainage unit is left in the soil to directly improve the soil bearing capacity, allowing large machinery to enter. It simultaneously achieves drainage and improves the soil bearing capacity. Moreover, the structure is simple and can be manually installed without mechanical assistance. It overcomes the shortcomings of existing technologies where the bearing capacity improvement effect after dewatering of soft foundations with high water content is poor, requiring secondary reinforcement treatment. Example 2

[0025] Based on the vacuum-assisted composite rigid drainage device described in Example 1, such as Figure 5 As shown, this embodiment discloses a vacuum-assisted composite rigid drainage method, including the following steps: S10. First, prepare several vertical drainage units 1, prepare rigid plate-shaped parts 11, wrap drainage ropes 12 around the outer surface of rigid plate-shaped parts 11 and fix them with binding straps, and then wrap a layer of permeable geotextile 13 around the outside of rigid plate-shaped parts 11. In this step, bamboo boards can be used for rigid plate-shaped parts 11 and KP ropes can be used for drainage ropes 12. Workers manually insert vertical drainage units 1 into the soft mud of the weak foundation treatment area, so that several vertical drainage units 1 are arranged in a houndstooth or grid pattern in the weak foundation; bamboo boards provide sufficient rigidity and strength for the dewatering units, allowing them to be manually inserted into the dredged mud. KP ropes and bamboo boards together form vertical drainage channels, and permeable geotextiles mainly serve to filter soil particles; S20. From bottom to top, bamboo frame 21, geogrid 22, plastic mesh 23 and plastic film 3 are sequentially covered on the surface of the soft foundation treatment area. The bamboo frame 21, geogrid 22 and plastic mesh 23 form a rigid drainage support layer 2, and the plastic film 3 forms a flexible sealing layer. A drainage outlet 31 is provided at the center of the plastic film 3, and the edges of the plastic film 3 are compacted and sealed with sludge to ensure airtightness under vacuum conditions. The rigid horizontal drainage assembly is used to promote horizontal drainage in the sludge, provide sealing, transfer the applied load (external pressure load generated under vacuum negative pressure), and connect the rigid vertical drainage assembly to the vacuum auxiliary device. Specifically, the bamboo frame provides horizontal stiffness, and the geogrid and plastic mesh form horizontal drainage channels under vacuum preloading conditions. The plastic film is used to maintain the vacuum sealing performance of the system; S30, establish the vacuum auxiliary device, and connect the vacuum auxiliary device to the drain outlet 31 through the drain pipe; S40. Start the vacuum auxiliary device to apply negative pressure to the soft foundation treatment area. The water in the soil is extracted through the rigid vertical drainage component and the rigid horizontal drainage component to achieve soil dehydration. S50. During the drainage process, record the dehydration time and cumulative drainage volume, and calculate the average soil moisture content based on the measured cumulative drainage volume. When the average moisture content is close to the soil liquid limit, stop the vacuum auxiliary device. It should be noted that when a stable negative pressure cannot be maintained or there is no obvious water outflow from the hose, check and adjust the sealing. S60. After the soil dewatering is completed, an on-site plate load test is conducted on the soft foundation treatment area to evaluate the bearing capacity of the soil after dewatering. S70. Once the load-bearing capacity meets the requirements, retract the rigid horizontal drainage component to allow the mechanical equipment to enter for subsequent operations.

[0026] Using the above method, dehydration (from 114% to 65% moisture content) can be completed in just 3-4 hours. After dehydration, removing the vacuum connection part allows the foundation to achieve a bearing capacity (30 kPa) sufficient for a 5-ton excavator to enter and exit. The method described in this invention can reduce the soil moisture content by approximately 20%-40% after 4 hours of dehydration, achieving rapid soil dehydration. After the dehydration operation is completed, the vertical drainage unit remains in the soil. The rigid plate-like component generates significant friction with the dehydrated soil, thus achieving a bearing capacity sufficient to support a 5-ton hydraulic excavator after 4 hours of dehydration, meeting the requirements for construction machinery to enter the site.

[0027] The method described in this invention is applicable to various water-bearing soil treatment scenarios, including but not limited to the dewatering and improvement treatment of bottom sediments in hydraulic structures such as reservoirs and sedimentation tanks to enhance their bearing capacity and stability; the reinforcement and treatment of silt in rivers and lakes, as well as soft soil foundations, to improve soil structure and engineering mechanical properties; the optimization of farmland drainage systems and wetland soil improvement to reduce soil moisture content and improve its utilization performance; and emergency rescue projects and temporary road paving scenarios, where rapid dewatering treatment improves the foundation bearing capacity to meet short-term traffic and construction needs.

Claims

1. A vacuum-assisted composite rigid drainage device, characterized in that, Including, A rigid vertical drainage assembly includes several vertical drainage units (1) inserted vertically into a soft foundation. Each vertical drainage unit (1) includes a rigid plate (11) with vertically distributed drainage ropes (12) on its surface. A rigid horizontal drainage assembly includes a rigid drainage support layer (2) covering a soft foundation surface, a flexible sealing layer on the rigid drainage support layer (2), and a drainage outlet (31) on the flexible sealing layer. A vacuum-assisted device, which is connected to the drain outlet (31) via a drain pipe.

2. The vacuum-assisted composite rigid drainage device according to claim 1, characterized in that, The drainage rope (12) is an ethylene propylene copolymer rope.

3. The vacuum-assisted composite rigid drainage device according to claim 2, characterized in that, The rigid plate-shaped member (11) is also provided with a permeable geotextile (13) that wraps around the drainage rope (12).

4. The vacuum-assisted composite rigid drainage device according to claim 3, characterized in that, The flexible sealing layer is a plastic film (3).

5. The vacuum-assisted composite rigid drainage device according to claim 4, characterized in that, The rigid drainage support layer (2) consists of a bamboo frame (21), a geogrid (22), and a plastic mesh (23) from bottom to top.

6. The vacuum-assisted composite rigid drainage device according to claim 2, characterized in that, The drainage rope (12) is wound around the rigid plate (11) in the vertical direction, and the drainage rope (12) is fixed to the rigid plate (11) by multiple straps.

7. The vacuum-assisted composite rigid drainage device according to claim 1, characterized in that, The vacuum assist device includes a vacuum pump (4), a filter (5), and a water tank (6).

8. The vacuum-assisted composite rigid drainage device according to any one of claims 1-7, characterized in that, The vertical drainage units (1) are arranged in an array within the soft foundation.

9. A vacuum-assisted composite rigid drainage method, characterized in that, The vacuum-assisted composite rigid drainage device described in claim 5 is used to drain water from soft foundations with high water content, comprising the following steps: S10. First, prepare several vertical drainage units (1), prepare rigid plate-shaped parts (11), wrap the drainage rope (12) around the outer surface of the rigid plate-shaped parts (11) and fix it, and then wrap a layer of permeable geotextile (13) around the outside of the rigid plate-shaped parts (11). Workers manually insert the vertical drainage unit (1) vertically into the soft mud in the soft foundation treatment area, so that several vertical drainage units (1) are distributed in an array in the soft foundation; S20. From bottom to top, bamboo frame (21), geogrid (22), plastic mesh (23) and plastic film (3) are sequentially covered on the surface of the soft foundation treatment area. The bamboo frame (21), geogrid (22) and plastic mesh (23) form a rigid drainage support layer (2), and the plastic film (3) forms a flexible sealing layer. A drainage outlet (31) is provided at the center of the plastic film (3). The edges of the plastic film (3) are compacted and sealed with sludge to ensure airtightness under vacuum conditions. S30. Establish a vacuum auxiliary device and connect the vacuum auxiliary device to the drain outlet (31) through the drain pipe. S40. Start the vacuum auxiliary device to apply negative pressure to the soft foundation treatment area. The water in the soil is extracted through the rigid vertical drainage component and the rigid horizontal drainage component to achieve soil dehydration. S50. During the drainage process, record the dehydration time and cumulative drainage volume, and calculate the average soil moisture content based on the measured cumulative drainage volume. When the average moisture content is close to the soil liquid limit, stop the vacuum-assisted device. S60. After the soil dewatering is completed, an on-site plate load test is conducted on the soft foundation treatment area to evaluate the bearing capacity of the soil after dewatering. S70. Once the load-bearing capacity meets the requirements, retract the rigid horizontal drainage component to allow the mechanical equipment to enter for subsequent operations.

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