Device and method for anti-clogging drainage of soft soil foundation under synergistic effect of air jet flow and high-frequency sound waves

Abstract

The invention belongs to the technical field of soft soil foundation treatment, and particularly relates to an air jet flow-high-frequency sound wave synergistic effect soft soil foundation anti-clogging drainage device and method.The air jet flow-high-frequency sound wave synergistic effect soft soil foundation anti-clogging drainage device comprises an air compressor and a main air path connected with the air compressor and further comprises a plurality of drainage plates, and each drainage plate is provided with a spiral air pipe; the main gas circuit is connected with a spiral gas pipe through a plurality of branches, a Helmholtz resonance nozzle is arranged on the spiral gas pipe, the drainage channel is provided with a gas-liquid dual-purpose pump, the tail end of the drainage channel is communicated with a water collecting well, the water inlet end of the drainage channel is connected with each drainage plate through a connector and a drainage branch, and the water outlet end of the drainage channel is connected with the spiral gas pipe. According to the device, a desilting-(acoustic shock) dehydration-drainage integrated design method is adopted, and while filter membrane clogging of the plastic drainage plate is effectively removed, separation of bound water (or attached water) in sludge is promoted, which is the key to improvement of drainage efficiency, guarantee of consolidation quality and shortening of construction period. The problems of filter membrane clogging and low drainage efficiency of a traditional plastic drainage plate in soft foundation treatment are successfully solved. Even under the working condition of low water content, efficient desilting can be achieved, and the drainage consolidation quality and efficiency of the soft foundation are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soft soil foundation treatment, and particularly relates to a device and method for preventing clogging and draining of a soft soil foundation through air jet-high frequency sound wave cooperation. BACKGROUND

[0002] Soft soil is widely distributed in China, has high water content, poor water permeability, rheological property, large pore ratio and low shear strength. The foundation formed by soft soil is weak in overall, poor in water permeability, low in bearing capacity, weak in strength, poor in stability, and prone to uneven settlement, and thus cannot meet the requirements of engineering construction. Therefore, the soft soil foundation needs to be treated in advance before construction. The commonly used soft soil foundation treatment methods include cement mixing pile, gravel pile, bagged sand well method and plastic drainage plate method.

[0003] The cement mixing pile uses cement slurry or cement powder as a solidifying agent to be forcibly mixed with soft soil at a deep position of the foundation by a deep mixing machine, so as to form a composite foundation, thereby improving the bearing capacity and reducing the settlement. However, this method has high cost, poor quality control and large interference to underground facilities. The gravel pile uses unbound gravel (or pebble) as the main material, and forms a hole in the soft foundation by vibration, impact or water flushing, and then the gravel (or pebble) is extruded into the hole to form a large-diameter compact pile, thereby forming a composite foundation reinforcement form in which the gravel (or pebble) pile and the soil between the piles jointly act. However, this method has low compaction effect, small side pressure for extruding the soil on the side of the pile, and poor reinforcement effect on the soil between the piles. The bagged sand well method and the plastic drainage plate method both belong to the method of setting a vertical drainage system. The bagged sand well method encapsulates the bulk sand in an elongated bag made of chemical fiber fabric and placed in the soft soil, drains the pore water of the foundation soil, shortens the consolidation time, and improves the bearing capacity of the foundation. The plastic drainage plate method uses the plastic drainage plate to add a vertical drainage path of the soil layer, shortens the drainage distance, and accelerates the consolidation of the foundation. This method is simple in construction, reliable in quality, and fast in speed, and in recent years, it is gradually replacing the bagged sand well method and becoming the most widely used vertical drainage material.

[0004] However, in the process of using plastic drainage board for drainage consolidation, there has been a long-standing problem of filter membrane clogging leading to poor drainage and difficulty in effectively draining the combined water (or attached water) in the sludge, which seriously affects the drainage efficiency and consolidation quality. Patent No. CN202420386077.6 discloses "a device for promoting soft soil foundation drainage by air jet cutting", which inserts a rotating dredging pipe in the range of plastic drainage board arrangement for dredging, which can remove drainage board clogging, but has problems such as complex construction process, small dredging radius, etc. Patent No. CN202411173295.2 discloses "a drainage body, system and method for ultra-soft soil foundation drainage and consolidation", which uses straw drainage body and curing agent solution to realize rapid dehydration and consolidation of ultra-soft soil foundation and carbon sequestration, but has problems such as long time required for consolidation treatment, and low effect under low water content conditions. SUMMARY

[0005] The purpose of the present application is a method and device for preventing clogging of soft soil foundation drainage by air jet-high frequency sound wave synergistic effect. The device uses a dredging-(sonic shock) dehydration-drainage integrated design method to effectively remove plastic drainage board filter membrane clogging while promoting the separation of combined water (or attached water) in sludge, which is the key to improving drainage efficiency, ensuring consolidation quality and shortening construction period.

[0006] To achieve the above purpose, the technical solution adopted by the present application is: A device for preventing clogging of soft soil foundation drainage by air jet-high frequency sound wave synergistic effect, comprising an air compressor, a total gas path connected to the air compressor, an inlet total valve provided on the total gas path for controlling gas supply in the gas path, and the air compressor for continuously providing high-pressure gas to the anti-clogging drainage board; further comprising a plurality of drainage boards, each drainage board being provided with a spiral air pipe, the total gas path being connected to the spiral air pipes through a plurality of branches, the spiral air pipe being provided with a Helmholtz resonance nozzle, further comprising a drainage channel, the drainage channel being provided with a gas-liquid pump, the end of the drainage channel being communicated with a water collecting well, the water inlet end of the drainage channel being connected to each drainage board through a joint and a drainage branch, and the groundwater, pore water and separated combined water in the sludge entering the fully automatic anti-clogging drainage board under the negative pressure action of the gas-liquid pump, and flowing to the water collecting well through the drainage channel branch pipe.

[0007] Further, the Helmholtz resonance nozzle is made of 316L stainless steel, the Helmholtz resonance nozzle body comprises an upstream nozzle, an oscillation cavity and a downstream nozzle which are communicated with each other, a fixed rod is arranged at the connection between the upstream nozzle and the oscillation cavity, an inclined turbine blade is arranged in the oscillation cavity at the end of the fixed rod, and the central axes of the upstream nozzle, the inclined turbine blade and the downstream nozzle coincide; during operation, the boundary layer disturbance generated by the upstream nozzle is amplified by the oscillation cavity, and then a ring-shaped vortex is formed, the vortex structure can block the continuity of the jet flow, so that a self-vibration pulse jet flow is generated. The pulse jet flow forms a high-frequency sound wave at the outlet of the downstream nozzle, the high-frequency sound wave can effectively strip the combined water in the silt around the drainage plate, and under the action of the inclined turbine blade, a rotational flow is generated in the oscillation cavity under high pressure. When the rotational flow leaves the nozzle outlet, the silt around the drainage plate can be effectively removed.

[0008] Further, the spiral air pipe is sequentially provided with a plurality of Helmholtz resonance nozzles along the length direction.

[0009] Further, the drainage plate comprises a core plate located at the center, the core plate is formed by mixing and blending polypropylene and polyethylene, a plurality of longitudinal capillary holes and lateral capillary holes are arranged in the core plate, the longitudinal capillary holes and the lateral capillary holes are communicated with drainage branches, a filter membrane is wrapped outside the core plate, the filter membrane is made of long-fiber hot-rolled non-woven fabric, and the filter membrane is provided with a pore size of not greater than 75 μm; during use, the plastic drainage plate is used as a core vertical drainage component, is inserted into the soft soil foundation by means of a plate inserting machine, the core plate is mixed and blended by polypropylene (PP) and polyethylene (PE), and has the rigidity of polypropylene and the flexibility and weather resistance of polyethylene. The filter membrane wrapped outside the core plate is made of long-fiber hot-rolled non-woven fabric, and has excellent water resistance and permeability. The filter membrane can adjust and replace the pore size according to the particle size of the silt, and the equivalent pore size is generally less than 75 μm, so that the best mud-water separation effect is achieved. The plate body is provided with longitudinal gaps and lateral pores, so that the vertical drainage is smooth, the spiral air pipe is tightly wrapped outside the plastic drainage plate, and high-pressure gas enters the spiral air pipe through the air path and reaches the nozzle.

[0010] Further, the spiral air pipe is made of epoxy-coated carbon steel, can withstand the pressure of 15 m deep silt, and the epoxy coating has excellent corrosion resistance in the soil environment with pH=3-11.

[0011] Further, the inclined turbine blade is provided with a bearing and a bearing sleeve at the center, a blade is arranged outside the bearing sleeve, the attack angle of the blade is 22°, the inclination angle is 45°, the number of blades is 12, the blade is made of 316L stainless steel, the turbine is installed in the oscillation cavity of the Helmholtz resonance nozzle, and can generate a rotational flow with an angular velocity of ≥300 rad / s under a working pressure of 2.0 MPa; the rotational flow is directly acted on the silt after being sprayed out of the nozzle, so that the silt is effectively removed.

[0012] The application discloses a kind of soft soil foundation anti-silt drainage methods of air jet-high frequency acoustic wave synergy, comprising the following steps: S1. according to actual demand design planning anti-silt drainage board arrangement and installation spacing, its spacing is 0.9m; S2. after inserting anti-silt drainage board and setting multiple water collecting wells after laying sand cushion on pre-treatment site, drainage board exposed length is not less than 50cm; S3. in the anti-silt drainage board arrangement area, the number of drainage board is designed and planned, is determined according to air compressor exhaust volume Q, calculation formula is as formula 1;Wherein the gas quantity through nozzle outlet in unit time is Q1, is determined by the resonance cavity volume of Helmholtz resonance nozzle;N is the number of anti-silt drainage board, is determined by air compressor exhaust volume;Single anti-silt drainage board carries the number of nozzle m;Gas loss a in gas path transmission process, (1) S4. laying drainage channel, connecting adjacent two anti-silt drainage boards, and converging to drainage channel main pipe, water flow is finally led to water collecting well and handled; S5. installing air compressor, laying gas path, connecting anti-silt drainage board and installing air inlet total valve; S6. check the gas tightness of pipeline and interface, confirm no error, open air compressor and set air compressor parameter, when pressure is 10MPa, air compressor stops working, when pressure is less than 10MPa, automatically pressurizes; S7. after setting the parameter of air compressor, gas enters Helmholtz resonance nozzle via spiral gas path, generates spiral flow and high frequency acoustic wave in nozzle, achieves the effect of removing silt around adjacent horizontal drainage board and stripping the combined water of silt around drainage board, spiral flow angular velocity calculation formula is as formula 2, 3;High frequency acoustic wave frequency size generated by resonance calculation formula is as formula 4; (2) Wherein v θ It is tangential velocity component (m / s) of airflow, R is turbine radius (m).

[0013] (3) Wherein v x It is axial airflow velocity (m / s), β It is blade rake angle (°).

[0014] (Hz) (4) Wherein c is air speed 340m / s, A n Neck opening boundary area m 2 , V cV is the volume of the cavity m 3 , L L is the actual length of the neck m, r R is the radius of the neck.

[0015] S8. After completing steps S1-S7, a load is applied above the soft soil, and the drainage consolidation process of the soft soil foundation can be quickly completed.

[0016] The present application has the advantages of: 1. The new soft foundation treatment device uses nozzle self-vibration to generate high-frequency sound waves, effectively promoting the desorption of bound water in silt, especially suitable for low silt moisture content conditions, and can significantly ensure the quality of soft foundation drainage consolidation; 2. The new soft foundation treatment device generates high-speed rotational flow by setting a diagonal turbine blade inside the nozzle, efficiently removes plastic drainage plate filter membrane blockage, significantly improves soft foundation drainage efficiency and significantly shortens the construction period; 3. The device has a simple and compact structure, wide application range, realizes dredging-(acoustic shock) dewatering-drainage integration, effectively removes plastic drainage plate filter membrane blockage, promotes the separation of bound water (or attached water) in silt, and supports unmanned and fully automatic operation. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the front view structural schematic diagram of the soft soil foundation anti-blocking drainage device of the air jet-high frequency sound wave synergistic effect in the present application.

[0018] Figure 2 is the top view structural schematic diagram of the soft soil foundation anti-blocking drainage device of the air jet-high frequency sound wave synergistic effect in the present application.

[0019] Figure 3 is the structural schematic diagram of the drainage plate and the Helmholtz resonance nozzle in the present application, wherein a is the drainage plate structure diagram, and b is the Helmholtz resonance nozzle sectional view.

[0020] Figure 4 is the structural schematic diagram of the diagonal turbine blade in the present application. DETAILED DESCRIPTION

[0021] As Figures 1-4The device and method for preventing siltation and draining of soft soil foundation by air jet-high frequency sound wave synergy, the core components of the device include: air compressor 1, inlet valve 2, drainage channel 3, air path 4, gas-liquid pump 5, water collecting well 6, full-automatic anti-silt drainage plate 7, spiral air path 8, Helmholtz resonance nozzle 9, plastic drainage plate 10, upstream nozzle inlet 11, upstream nozzle outlet 12, oscillation cavity 13, inclined turbine blade 14, fixed rod 15, downstream nozzle 16, bearing 17, bearing sleeve 18, inclined turbine blade 19, etc. First, use the drilling machine to drill to the designed depth in the soft soil foundation to be treated, install the anti-silt drainage plate 7 according to the predetermined arrangement mode, and connect it to the drainage channel 3 and the air path 4. Turn on the air compressor 1 and set the parameters, set the system working pressure threshold to 10 MPa: when the pressure is higher than 10 MPa, the air compressor stops working, and when the pressure is lower than 10 MPa, the air compressor automatically starts to pressurize. Keep the air compressor 1 running continuously, and inject gas into the air path 4. After the high-pressure gas flows through the anti-silt drainage plate 7, it enters the spiral air path 8, and then enters the Helmholtz resonance nozzle 9. The gas continuously accelerates to supersonic speed in the nozzle. After the high-speed gas reaches the oscillation cavity 13 inside the Helmholtz resonance nozzle 9, it resonates, and under the action of the inclined turbine blade 14, a circumferential air jet is generated in the oscillation cavity 13. This jet can efficiently flush the silt around the adjacent drainage plate after leaving the nozzle. At the same time, under the resonance action of the Helmholtz resonance cavity 13, high-frequency ultrasonic waves are formed at the nozzle outlet, which can effectively strip the combined water in the silt around the adjacent drainage plate. Start the gas-liquid pump 5 to apply negative pressure, quickly drain the groundwater, pore water in the soft soil foundation, and combined water separated from the silt under the action of ultrasonic waves. The drained water is collected in the water collecting well 6. The above process automatically circulates. Using this method and device for drainage consolidation, the problems of filter membrane siltation and low drainage efficiency faced by traditional plastic drainage plates in soft foundation treatment are successfully solved. Even in low water content conditions, efficient desilting can be achieved, significantly improving the quality and efficiency of soft foundation drainage consolidation.

Claims

1. An air jet-high frequency acoustic wave synergy soft soil foundation anti-clogging drainage device, characterized in that: It includes an air compressor, a main air circuit connected to the air compressor, and multiple drain plates. Each drain plate is equipped with a spiral air pipe. The main air circuit is connected to the spiral air pipe through multiple branches. The spiral air pipe is equipped with a Helmholtz resonant nozzle. It also includes a drainage channel. The drainage channel is equipped with a gas-liquid dual-purpose pump. The end of the drainage channel is connected to a water collection well. The water inlet of the drainage channel is connected to each drain plate through a connector and a drainage branch.

2. The air jet-high frequency acoustic wave synergy soft soil foundation anti-clogging drainage device according to claim 1, characterized in that: The Helmholtz resonant nozzle is made of 316L stainless steel. The main body of the Helmholtz resonant nozzle includes an upstream nozzle, an oscillation chamber and a downstream nozzle that are interconnected. A fixing rod is provided at the connection between the upstream nozzle and the oscillation chamber. An inclined turbine blade is installed at the end of the fixing rod, which is inside the oscillation chamber. The central axes of the upstream nozzle, the inclined turbine blade and the downstream nozzle are coincident.

3. The air jet-high frequency acoustic wave synergy soft soil foundation anti-clogging drainage device according to claim 1, characterized in that: Multiple Helmholtz resonance nozzles are sequentially arranged along the length of the spiral tube.

4. The air jet-high frequency acoustic wave synergy soft soil foundation anti-clogging drainage device according to claim 1, characterized in that: The drainage board includes a core board located at the center. The core board is made of polypropylene and polyethylene mixed and molded. The core board has multiple longitudinal capillary pores and lateral capillary pores inside. The longitudinal capillary pores and lateral capillary pores are all connected to the drainage branches. The core board is wrapped with a filter membrane. The filter membrane is made of long-fiber hot-rolled non-woven fabric and has a pore size of no more than 75μm.

5. The air jet-high frequency acoustic wave synergy soft soil foundation anti-clogging drainage device according to claim 1, characterized in that: The spiral air tube is made of epoxy-coated carbon steel.

6. The air jet-high frequency acoustic wave synergy soft soil foundation anti-clogging drainage device according to claim 3, characterized in that: The inclined turbine blade is provided with a bearing and a bearing sleeve at its center, and blades are provided outside the bearing sleeve. The blades have an angle of attack of 22° and an inclination angle of 45°. There are 12 blades, which are made of 316L stainless steel.

7. A method of draining according to any one of claims 1-6, characterized in that Includes the following steps: S1. The layout and installation spacing of the anti-siltation and drainage boards are designed and planned according to actual needs, with a spacing of 0.9m; S2. After laying a sand cushion layer on the pretreatment site, insert anti-siltation and drainage boards and drill multiple water collection wells. The exposed length of the drainage boards shall not be less than 50cm. S3. Within the area where the anti-siltation drainage boards are arranged, the number of drainage boards is designed and planned, and determined based on the air compressor discharge capacity Q, and the calculation formula is as shown in Formula 1; The gas volume passing through the nozzle outlet per unit time is Q1, determined by the resonant cavity volume of the Helmholtz resonant nozzle; n is the number of anti-sludge drainage plates, determined by the exhaust volume of the air compressor; each anti-sludge drainage plate carries m nozzles; and a is the gas loss during gas transmission. （1） S4. Lay drainage channels, connect two adjacent anti-siltation drainage boards, and collect water into the main drainage channel. The water flow eventually leads to the collection well for treatment. S5. Install the air compressor, lay the air lines, connect the anti-siltation and drainage boards, and install the main air inlet valve; S6. Check the air tightness of the pipeline and interface. After confirming that there is nothing wrong, turn on the air compressor and set the air compressor parameters. When the pressure is 10MPa, the air compressor stops working. When the pressure is lower than 10MPa, it will automatically pressurize. S7. After setting the parameters of the air compressor, the gas enters the Helmholtz resonant nozzle through the spiral air path, generating swirling flow and high-frequency sound waves in the nozzle, achieving the effect of removing the silt around the adjacent horizontal drainage board and stripping the bound water of the silt around the drainage board. The formula for calculating the swirling angular velocity is as shown in Equations 2 and 3; the formula for calculating the frequency of the high-frequency sound waves generated by the resonance is as shown in Equation 4. （2） wherein v θ is the tangential velocity component of the gas flow (m / s), R is the turbine radius (m); （3） wherein v x is the axial gas flow velocity (m / s), β is the blade pitch angle (°); (Hz) (4) where c is the speed of sound in air 340 m / s, A n Aneckis the neck opening area m 2 , V c Vcavityis the cavity volume m 3 , L Aneckis the neck opening area m, r Aneckis the neck opening area m, S8. After the steps S1-S7 are completed, a load is applied above the soft soil, and the drainage consolidation process of the soft soil foundation can be quickly completed.

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