A municipal well base reinforcement system and method based on electro-osmotic grouting

Abstract

This application provides a municipal manhole base reinforcement system and method based on electroosmotic grouting, mainly including: minimally invasively implanting electrodes around the manhole base and injecting grout; after energizing, using the electroosmotic effect to drive the grout to diffuse directionally and uniformly into the surrounding silty soil; using intermittent energizing to gel the grout, forming a deep reinforced shell; and finally performing shallow low-pressure grouting to seal the top. This achieves precise, efficient, and durable reinforcement of the soil around the manhole, fundamentally blocking the settlement path, and the construction is minimally invasive, safe, and eliminates the risk of manhole blockage.

Description

Technical Field

[0001] This application relates to the fields of geotechnical engineering and municipal facility maintenance technology, specifically to a municipal manhole base reinforcement system and method based on electroosmotic grouting. Background Technology

[0002] Settlement around municipal manhole covers is a common "urban problem," primarily caused by the difficulty in compacting the backfill soil (mostly silty clay or muddy soil) around the manholes. Under long-term vehicle loads and groundwater seepage, the soil softens and erodes, forming cavities and uneven settlement. Existing remediation methods have significant shortcomings: Excavation and replacement method: requires large-scale demolition of the road surface, has a long construction period, high cost, significant traffic disruption, and is prone to further settlement in the later stages.

[0003] Conventional pressure grouting: In low-permeability silty soils, the grout is difficult to diffuse evenly, easily forming fractured channels and resulting in uneven reinforcement. Grouting pressure is difficult to control; high pressure can cause grout to seep into plastic well joints or cavities, causing permanent blockage. The grout and silt are difficult to bond effectively, resulting in low strength and poor long-term durability of the solidified body.

[0004] Electro-osmotic grouting methods mainly include curtain grouting and high-pressure jet grouting. Curtain grouting is a grouting method that forms a continuous seepage-proof curtain in permeable rock and soil through low-pressure grouting. High-pressure jet grouting involves drilling a hole with a nozzle and inserting a grouting pipe into the hole to a predetermined depth. High-pressure equipment is then used to create a high-pressure flow of grout, water, and air, which impacts and damages the soil. Some fine soil particles emerge from the hole with the grout, while the remaining soil particles are mixed with the grout under the influence of impact, centrifugal force, and gravity, and rearranged in a regular manner according to a certain grout-to-soil ratio. The grout then solidifies to form a cement-soil reinforced body. This method is often used for large-area soft soil foundation treatment, mainly utilizing electric field drainage consolidation. However, it lacks synergy with the depth of material improvement and is not suitable for shallow, localized well base reinforcement scenarios that require rapid structural strength formation. Furthermore, its long-term stability is poor.

[0005] When the soil to be reinforced is below the groundwater level, and both the upper and lower layers are impermeable, and the soil contains multiple types of soil layers, traditional grouting methods, whether curtain grouting or high-pressure jet grouting, struggle to guarantee the grouting quality and achieve the desired grouting effect. Therefore, there is an urgent need for a new, targeted, minimally invasive, uniformly and sustainably reinforcing technology for wellhead settlement control that effectively avoids secondary risks. Summary of the Invention

[0006] In view of this, this application proposes a treatment method and a special system for uneven settlement around the base of municipal wells, rainwater wells and other wells. It utilizes the principle of electroosmosis to drive the directional diffusion of functional slurry and combines it with a layered solidification process to achieve minimally invasive, efficient and durable reinforcement.

[0007] Specifically, a municipal manhole base reinforcement system based on electroosmotic grouting is provided, which mainly includes: a composite electrode module, an intelligent control unit, a special functional grout, and a shallow compensation grouting unit.

[0008] More specifically, the composite electrode module mainly consists of several hollow electrode rods. The rod body is made of corrosion-resistant conductive material. The inside of the electrode rod is a cavity, and the lower half of the rod body is provided with densely distributed micropores. The holes near the outer edge are preset as anode rod holes, and the holes near the well wall are preset as cathode rod holes. The anode rod serves as a slurry channel, and the cathode rod is used as a drainage electrode.

[0009] More specifically, the intelligent control unit includes a DC power supply module, a current / voltage monitoring module, and a programmable logic controller (PLC). It can output an adjustable DC voltage of 0-100V and has intermittent pulse power supply mode and constant current control mode. The PLC can automatically adjust the output parameters according to the set logic based on the real-time monitored current and soil resistance data.

[0010] More specifically, the main components of the special functional slurry by weight are: water glass, modulus 2.8-3.2, concentration 35-40Be'; calcium chloride 5-15 parts; ultrafine silica fume 5-10 parts; nonionic surfactant 0.1-0.5 parts; water 10-20 parts; the initial viscosity of this special functional slurry is less than 50 mPa·s, and the gelation time can be controlled within 2-8 hours by adjusting the specific gravity of calcium chloride in the coagulant.

[0011] More specifically, the shallow compensation grouting unit, comprising a lightweight grouting pump and a micro-expansion cement-based grout, is used for the third stage of construction.

[0012] On the other hand, the above-mentioned method of using the municipal manhole base reinforcement system based on electroosmotic grouting mainly includes: implanting electrodes around the manhole base with minimal invasiveness and injecting grout; after energizing, using the electroosmotic effect to drive the grout to diffuse in a directional and uniform manner into the surrounding silty soil; using intermittent energizing to gel the grout and form a deep reinforced shell; and finally performing shallow low-pressure grouting to seal the top.

[0013] More specifically, the main steps are as follows: Step 1: On-site diagnosis and borehole design. Use ground penetrating radar to scan the area around the well to determine the range of loose soil. With the well as the center, in a ring area with a radius of 0.8-1.2m, two rings of drilling points are staggered at intervals of 0.4-0.6m. The ring of holes closer to the outer edge is preset as anode, and the ring of holes closer to the well wall is preset as cathode.

[0014] Step 2: Minimally invasive drilling and electrode implantation. Use a small drilling machine to drill a hole with a diameter of about 30-40mm to the predetermined depth. Insert the hollow electrode rod of the composite electrode into the hole, ensuring that the bottom of the electrode contacts the target reinforcement layer. The anode rod is implanted in the holes near the outer edge, and the cathode rod is implanted in the holes near the well wall.

[0015] Step 3: Electroosmosis drives slurry diffusion. Connect the special functional slurry delivery pump to all anode rods and slowly inject the slurry into the anode rods until the slurry seeps out from the micropores of the rod body and contacts the soil on the borehole wall. Connect the electroosmosis intelligent control unit, turn on the power, and under the action of the electric field, the cations in the slurry carry water molecules and the slurry as a whole to migrate directionally toward the cathode. This process lasts for 12-48 hours until the cathode drainage is significantly reduced and the current tends to stabilize.

[0016] Step 4: Intermittent power curing. During this stage, the intelligent control unit switches to intermittent pulse mode and applies power for 24-72 hours. Under the action of electric field and chemical action, the slurry undergoes full ion exchange and gelation reaction with soil particles to form a water-stable solidified body, which binds the dispersed soil particles into an overall network structure, significantly improving the compressive strength and impermeability of the soil.

[0017] Step 5: Shallow low-pressure compensation grouting. After removing the electrodes, shallow holes are drilled obliquely into the road structure layer below the manhole base to the top surface of the formed electro-osmotic reinforced body. Micro-expansion cement grout is injected at a low pressure of less than 0.5 MPa to fill all loose voids and delamination areas in the upper part of the electro-osmotic reinforced layer, forming a complete "pressure-bearing cover plate" and bonding the manhole base, reinforced body and upper roadbed into a whole.

[0018] Step 6: Effect evaluation and restoration. The reinforcement effect is verified by core drilling or a nucleus-free density meter. Finally, the electrode holes and grouting holes are backfilled with rapid repair material to restore the road surface.

[0019] The technical solution proposed in this application has the following innovative features and beneficial effects compared with the prior art.

[0020] Minimally invasive and efficient: Only small holes need to be drilled, without large-scale excavation, and the construction speed is fast (usually completed in 3-5 days), minimizing the impact on municipal traffic and the environment.

[0021] Thorough and uniform reinforcement: Driven by an electric field, the grout achieves directional and uniform penetration and diffusion in difficult-to-treat silty soil, avoiding the uneven splitting problem of pressure grouting, and forming a continuous and complete reinforced shell.

[0022] Anti-slurry migration, safe and reliable: The low-pressure, electric field-driven slurry migration method eliminates the risk of high pressure squeezing into the plastic well body in principle. The process sequence of "first deep electroosmosis solidification to form a water-resistant support layer, then shallow grouting" further ensures safety.

[0023] High strength and durability: The synergistic effect of "electro-osmotic drainage" and "chemical cementation" not only allows for rapid drainage, but also generates a water-resistant and high-strength cementitious body through the chemical reaction between the slurry and the soil. Its long-term stability is far superior to simple drainage or physical filling.

[0024] Highly intelligent and controllable: The intelligent control system monitors electrical parameters in real time, which can indirectly sense the reinforcement process, optimize the process, and ensure controllable quality. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0027] Figure 1 This is a schematic diagram of a municipal manhole base reinforcement system based on electroosmotic grouting according to this application. Detailed Implementation

[0028] The embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the 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.

[0029] This application provides a municipal manhole seat reinforcement system and method based on electroosmotic grouting, which is a minimally invasive reinforcement system and method based on electroosmotic driving and layered solidification to prevent the settlement of municipal manhole seats. The system mainly includes: a composite electrode module, an intelligent control unit, a special functional grout, and a shallow compensation grouting unit.

[0030] A municipal well seat reinforcement system based on electroosmotic grouting mainly includes: a composite electrode module, an intelligent control unit, a special functional grout, and a shallow compensation grouting unit.

[0031] Composite Electrode Module: The composite electrode module mainly consists of several hollow electrode rods. The rods are made of corrosion-resistant conductive materials (such as graphite or titanium-plated metal), with a diameter of 20-30mm and an adjustable length of 1.5-3.0m to adapt to different burial depths. The inside of the electrode rod is hollow, serving as a slurry channel; the lower half of the rod has densely distributed micropores to allow slurry seepage. The electrodes are divided into an anode (connected to the positive terminal of the power supply, used for injecting slurry and generating electroosmosis) and a cathode (connected to the negative terminal of the power supply, housing a small axial pressure pump; the densely distributed micropores of the cathode rod act as a drainage electrode under the suction of the small axial pressure pump). See Appendix. Figure 1 .

[0032] Intelligent control unit: Includes a DC power supply module, a current / voltage monitoring module, and a programmable logic controller (PLC). It can output an adjustable DC voltage from 0-100V and features an intermittent pulse power supply mode (e.g., 30 minutes on / 30 minutes off cycle) and a constant current control mode to optimize energy consumption and reduce electrode polarization. The PLC can automatically adjust output parameters based on real-time monitored current and soil resistance data, according to predefined logic.

[0033] Special functional slurry: The special functional slurry is a chemical slurry with low viscosity, high permeability, good conductivity, and controllable gelation time.

[0034] The main components (by weight) of the special functional slurry are: 100 parts water glass (modulus 2.8-3.2, concentration 35-40Be', corresponding to a mass percentage of approximately 25%-30%, the specific value will be affected by different moduli); 5-15 parts calcium chloride (as a coagulant and conductivity enhancer); 5-10 parts ultrafine silica fume (to improve final strength); 0.1-0.5 parts nonionic surfactant (to reduce interfacial tension and enhance penetration); and 10-20 parts water (to adjust viscosity). The initial viscosity of this special functional slurry is less than 50 mPa·s, and the gelation time can be controlled within 2-8 hours by adjusting the specific gravity of the calcium chloride in the coagulant.

[0035] Shallow compensation grouting unit: used for the third stage of construction, including a lightweight grouting pump and micro-expansion cement-based grout.

[0036] On the other hand, this application provides a method for using the above-mentioned electroosmotic grouting municipal manhole base reinforcement system, which mainly includes: minimally invasively implanting electrodes around the manhole base and injecting grout; after energizing, using the electroosmotic effect to drive the grout to diffuse directionally and uniformly into the surrounding silty soil; using intermittent energizing to gel the grout and form a deep reinforced shell; and finally performing shallow low-pressure grouting to seal the top.

[0037] The specific application method (overall construction method) follows the core logic of "diagnosis and positioning → deep electroosmosis-driven diffusion and solidification → shallow grouting and capping", and the specific steps are as follows: Preparatory stage Step 1: On-site diagnosis and borehole layout design. Use ground-penetrating radar to scan the area around the well to determine the extent of loose soil. Centered on the well shaft, within a ring-shaped area with a radius of 0.8-1.2m, lay out two concentric rings of boreholes spaced 0.4-0.6m apart. The ring of boreholes closer to the outer edge is pre-designated as anodes, and the ring of boreholes closer to the well wall is pre-designated as cathodes.

[0038] Step 2: Minimally Invasive Drilling and Electrode Implantation. A small drilling rig is used to drill a hole approximately 30-40mm in diameter to the predetermined depth (usually penetrating soft soil layers). The hollow electrode rod of the composite electrode is implanted into the hole, ensuring the bottom of the electrode contacts the target reinforcement layer. The anode rod is implanted in the outermost ring of holes, and the cathode rod is implanted in the ring of holes closest to the well wall.

[0039] Phase 1 Step 3: Electroosmosis drives slurry diffusion.

[0040] A dedicated slurry delivery pump is connected to all anode rods to slowly inject slurry into them until it seeps out from the micropores of the rod and contacts the soil in the borehole. The anode rods can also be called slurry inlet pipes. The negative terminal of the power supply is electrically connected to all cathode rods, and a small axial pressure pump is installed so that the cathode rods also serve as drainage electrodes.

[0041] Connect the electroosmosis intelligent control unit and turn on the power. Under the action of the electric field (E), the cations (M...) in the slurry... + The slurry carries water molecules and the entire slurry towards the cathode in a directional migration. This process lasts 12-48 hours until a significant reduction in cathode drainage and a stable current are observed, indicating that the slurry has fully diffused.

[0042] Phase Two Step 4: Intermittent power curing. Switch to intermittent pulse mode and apply power for 24-72 hours. During this stage, the grout undergoes sufficient ion exchange and gelation reaction with soil particles under the influence of electric field and chemical action, forming a water-stable solidified body. This binds the dispersed soil particles into an integral network structure, significantly improving the soil's compressive strength and impermeability.

[0043] Phase Three Step 5: Shallow Low-Pressure Compensation Grouting. After removing the electrodes, shallow holes are drilled obliquely into the pavement structure layer below the manhole cover, extending to the top surface of the formed electro-osmotic reinforced layer. Micro-expansion cement grout is injected at low pressure (<0.5MPa) to fill all loose voids and vacuoles in the upper part of the electro-osmotic reinforced layer, forming a complete "pressure-bearing cover" and bonding the manhole cover, reinforced layer, and upper roadbed into a unified whole.

[0044] Step 6: Effect Evaluation and Restoration. The reinforcement effect is verified by core drilling or a nucleus-free density gauge. Finally, the electrode holes and grouting holes are backfilled with rapid repair material to restore the road surface.

[0045] The following is in conjunction with the appendix Figure 1 This application will be described in detail with specific implementation examples of the preferred parameter conditions.

[0046] A 1.2-meter diameter plastic inspection well on a main road in a city experienced perimeter subsidence, with a subsidence depth of approximately 5 cm. Radar detection revealed a softened silt layer depth of approximately 1.8 meters.

[0047] Deployment: such as Figure 1 As shown, with the well center as the center, eight holes (four anodes and four cathodes alternately) are arranged at equal intervals on a circumference with a radius of 1.0m. The hole diameter is 35mm and the depth is 2.0m, and electrode rods are inserted into each hole.

[0048] Slurry preparation: Mix 100 kg of water glass (38Be'), 8 kg of anhydrous calcium chloride, 7 kg of silica fume, 0.3 kg of surfactant and 15 kg of water, and stir until uniform. The initial viscosity was measured to be approximately 45 mPa·s.

[0049] Electroosmotic diffusion: Approximately 20 L of the prepared slurry was injected through the anode into each well. Electroosmosis was then initiated with an initial voltage of 30 V DC and a constant current mode (initial current approximately 2 A). After 18 hours of energization, continuous water flow was observed from the cathode drain pipe, and the current slowly decreased to 1.2 A and stabilized.

[0050] Intermittent maintenance: Switch to intermittent mode (power on for 40 minutes, power off for 20 minutes), and continue running for 48 hours.

[0051] Shallow capping: Remove the electrodes, drill four shallow holes at a 45-degree angle around the well base to a depth of 0.6m, inject about 0.05m³ of micro-expansion cement slurry, and control the pressure at 0.3MPa.

[0052] Results: After 3 days of curing, core sampling showed that the average unconfined compressive strength of the soil within 1.0m of the well reached 0.8MPa (compared to approximately 0.05MPa for undisturbed soil), indicating stable settlement. A follow-up examination 3 months later showed no new settlement.

[0053] This implementation example utilizes a municipal well seat reinforcement system and method based on electroosmotic grouting proposed in this application to achieve precise, efficient, and durable reinforcement of the soil around the well, fundamentally blocking the settlement path. Moreover, the construction is minimally invasive, safe, and eliminates the risk of well blockage.

[0054] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A municipal manhole base reinforcement system based on electroosmotic grouting, characterized in that, Mainly includes: Composite electrode module, intelligent control unit, special functional grout, and shallow compensation grouting unit.

2. The municipal manhole base reinforcement system based on electroosmotic grouting according to claim 1, characterized in that, The composite electrode module is mainly composed of several hollow electrode rods. The rod body is made of corrosion-resistant conductive material. The inside of the electrode rod is a cavity. The lower half of the rod body is provided with densely distributed micropores. The holes near the outer edge are preset as anode rod holes, and the holes near the well wall are preset as cathode rod holes. The anode rod serves as a slurry channel, and the cathode rod serves as a drainage electrode.

3. The municipal manhole base reinforcement system based on electroosmotic grouting according to claim 1, characterized in that, Intelligent control unit: includes DC power supply module, current / voltage monitoring module and programmable logic controller, can output adjustable DC voltage from 0-100V, and has intermittent pulse power supply mode and constant current control mode. The programmable logic controller can automatically adjust the output parameters according to the set logic based on the real-time monitored current and soil resistance data.

4. The municipal manhole base reinforcement system based on electroosmotic grouting according to claim 1, characterized in that, The main components of the special functional slurry by weight are: water glass, modulus 2.8-3.2, concentration 35-40Be'; calcium chloride 5-15 parts; ultrafine silica fume 5-10 parts; nonionic surfactant 0.1-0.5 parts; water 10-20 parts. The initial viscosity of this special functional slurry is less than 50 mPa·s, and the gelation time can be controlled within 2-8 hours by adjusting the specific gravity of calcium chloride in the coagulant.

5. A municipal manhole base reinforcement system based on electroosmotic grouting according to claim 1, characterized in that, The shallow compensation grouting unit, comprising a lightweight grouting pump and micro-expansion cement-based grout, is used for the third stage of construction.

6. A method of using a municipal manhole base reinforcement system based on electroosmotic grouting according to any one of claims 1-5, characterized in that, Mainly includes: Electrodes were minimally invasively implanted around the well base and slurry was injected; after energization, the electroosmotic effect was used to drive the slurry to diffuse directionally and evenly into the surrounding silty soil. Intermittent energizing causes the grout to gel, forming a deep reinforced shell; finally, shallow low-pressure grouting is used for capping.

7. The specific method of using the municipal manhole base reinforcement system based on electroosmotic grouting according to claim 6, characterized in that, The main steps are as follows: Step 1: On-site diagnosis and borehole design. Use ground penetrating radar to scan the area around the well to determine the range of loose soil. With the well as the center, in a ring area with a radius of 0.8-1.2m, two rings of drilling points are arranged alternately at intervals of 0.4-0.6m. The ring of holes closer to the outer edge is preset as anode, and the ring of holes closer to the well wall is preset as cathode.

8. The specific method of using the municipal manhole base reinforcement system based on electroosmotic grouting according to claim 7, characterized in that, The main steps are as follows: Step 2: Minimally invasive drilling and electrode implantation. Use a small drilling machine to drill a hole with a diameter of about 30-40mm to the predetermined depth. Insert the hollow electrode rod of the composite electrode into the hole, ensuring that the bottom of the electrode contacts the target reinforcement layer. The anode rod is implanted in the holes near the outer edge, and the cathode rod is implanted in the holes near the well wall.

9. The specific method of using the municipal manhole base reinforcement system based on electroosmotic grouting according to claim 8, characterized in that, The main steps are as follows: Step 3: Electroosmosis drives slurry diffusion. Connect the special functional slurry delivery pump to all anode rods and slowly inject the slurry into the anode rods until the slurry seeps out from the micropores of the rod body and contacts the soil on the borehole wall. Connect the electroosmosis intelligent control unit, turn on the power, and under the action of the electric field, the cations in the slurry carry water molecules and the slurry as a whole to migrate directionally toward the cathode. This process lasts for 12-48 hours until the cathode drainage is significantly reduced and the current tends to stabilize.

10. The specific method of using the municipal manhole base reinforcement system based on electroosmotic grouting according to claim 9, characterized in that, The main steps are as follows: Step 4: Intermittent power curing. During this stage, the intelligent control unit switches to intermittent pulse mode and applies power for 24-72 hours. Under the action of electric field and chemical action, the slurry undergoes full ion exchange and gelation reaction with soil particles to form a water-stable solidified body, which binds the dispersed soil particles into an overall network structure, significantly improving the compressive strength and impermeability of the soil.

11. The specific method of using the municipal manhole base reinforcement system based on electroosmotic grouting according to claim 10, characterized in that, The main steps are as follows: Step 5: Shallow low-pressure compensation grouting. After removing the electrodes, shallow holes are drilled obliquely into the road structure layer below the manhole base to the top surface of the formed electro-osmotic reinforced body. Micro-expansion cement grout is injected at a low pressure of less than 0.5 MPa to fill all loose voids and delamination areas in the upper part of the electro-osmotic reinforced layer, forming a complete "pressure-bearing cover plate" and bonding the manhole base, reinforced body and upper roadbed into a whole.

12. The specific method of using the municipal manhole base reinforcement system based on electroosmotic grouting according to claim 11, characterized in that, The main steps are as follows: Step 6: Effect evaluation and restoration. The reinforcement effect is verified by core drilling or a nucleus-free density meter. Finally, the electrode holes and grouting holes are backfilled with rapid repair material to restore the road surface.

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