A recyclable magnetic slurry excitation grouting pipe valve and layered grouting detection method

Abstract

The application discloses a recyclable magnetic slurry excitation grouting pipe valve, which comprises a composite grouting pipe (1), an electromagnetic excitation valve group (2), a ground control unit (3) and a magnetic detection unit (4). The excitation coil (112) wound on the grouting outer pipe (11) attracts the magnetic line closed pipe (22). The electromagnetic excitation valve group (2) comprises a group of grouting valves (21) arranged along the slurry flow pipe (23), and the magnetic opening and closing device (212) of the grouting valve (21) pushes the pile side grouting device (213) to extend out of the corresponding rubber sleeve (115) on the grouting outer pipe (11) when the magnetic attraction force is applied, so that the grouting mode is opened. The ground control unit (3) is provided with an addressing control module. The magnetic detection unit (4) comprises a magnetic flux sensor array (41) uniformly distributed along the longitudinal direction of the reinforcement cage (5) and a ground data processing terminal (42). The application has the advantages of accurately detecting and controlling the slurry diffusion range, realizing layered fine grouting, and supporting the recycling of the grouting valve.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering grouting technology, and particularly relates to a recyclable magnetic grout-activated grouting pipe valve and its layered grouting detection method. Background Technology

[0002] Drilled piles are widely used in high-rise buildings, bridges, and port projects due to their high bearing capacity and adaptability. However, during the construction of drilled piles, excessively thick sediment at the pile bottom or mud cake on the pile side can significantly reduce the pile foundation's bearing capacity. Therefore, post-grouting technology has become a crucial step in improving the bearing capacity of pile foundations. Currently, the commonly used grouting devices in engineering are sleeve valve pipes and one-way grouting valves. However, in practical engineering applications, traditional grouting techniques have obvious defects and shortcomings.

[0003] First, traditional grouting valves use a passive opening mode, lacking active and precise control capabilities. Traditional sleeve valves and one-way grouting valves rely on grout pressure to open the valve. This passive opening mode has significant uncertainties and safety risks: when the grouting pipeline is long, or the target grouting layer is located in deep strata with high initial stratum pressure, extremely high pumping pressure is required to trigger valve opening. High-pressure conditions not only easily lead to grouting pipeline collapse and cracking, but also cause pressure attenuation and distortion during pipeline transmission, failing to accurately reflect the actual stress state of the target grouting layer.

[0004] Secondly, the diffusion state of the grout after injection into the formation is unknown, and there is a lack of intuitive and effective detection methods. In the existing grouting technology system, once the grout is injected underground, its actual flow direction, diffusion range, and filling effect are all in a black box. Engineering technicians can only indirectly infer the grouting effect through two parameters: the pumping pressure of the ground grouting pump and the cumulative grouting volume. They cannot intuitively grasp the diffusion of the grout in the target layer, nor can they identify abnormal conditions such as grout leakage or cross-contamination in a timely manner. The evaluation of grouting effect lacks a scientific and quantitative basis.

[0005] Third, it cannot achieve precise multi-depth layered grouting, and grout leakage between different layers is prone to interference. For grouting operations in deep foundations or multiple target layers, traditional grouting devices cannot independently open and control the flow of grouting units at different depths. Grout will preferentially overflow along the layer with the least resistance, often resulting in excessive grout overflow in some grouting layers, causing material waste, while the actual grout volume in the target grouting layer is insufficient, failing to achieve the expected reinforcement effect.

[0006] Fourth, the grouting valve body and pipelines cannot be recovered, resulting in material waste and the leaving of underground obstacles. Traditional grouting devices are basically designed for one-time burial. After the grouting operation is completed, the entire grouting valve body and connecting pipelines are left underground. On the one hand, this increases the material cost of the project, and on the other hand, the leftover metal valve body and pipelines will become obstacles for subsequent underground construction. They may also interfere with the geophysical signals of subsequent geological exploration and pile foundation testing, affecting the accuracy of the test results. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of passive grout valve opening, invisible grout diffusion state, difficulty in precise layer control, and inability to recycle grout valves in existing grouting processes. It provides a recyclable magnetic grout-activated grouting valve that can actively activate and open the grout valve, accurately detect and control the grout diffusion range, achieve fine layer grouting, and support the repeated recycling of the grout valve.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A recyclable magnetic grouting pipe valve mainly consists of a composite grouting pipe, an electromagnetic excitation valve assembly, a ground control unit, and a magnetic detection unit. The outer wall of the composite grouting pipe is layered with excitation coils according to the distribution of the magnetically sealed tubes inside the inner grouting pipe. The electromagnetic excitation valve assembly, i.e., an electromagnetically actively excited recyclable grouting valve assembly, is placed inside the inner grouting pipe. When magnetic grout is injected into the inner grouting pipe, the ground control unit activates the current flowing to the excitation coils. The external electromagnetic coil attracts the cylindrical permanent magnets inside the magnetically sealed tubes of the inner grouting pipe, which in turn attract the electromagnetic coils on the electromagnetic excitation valve assembly. Driven by the electromagnetic force generated in the external excitation coils, the valves of the electromagnetic excitation valve assembly actively open and close, achieving layered grouting.

[0009] The composite grouting pipe includes a grouting outer pipe and a grouting inner pipe made of non-magnetic material: The outer pipe of the grouting pipe is provided with a set of grouting hole sections distributed at equal intervals along the axial direction. Each grouting hole section has an excitation coil independently wound on its outer wall. They are in pairs. Each set of excitation coils is connected to an independent lead wire. The lead wire is led out along the pipeline and extends to the ground to connect with the ground control unit. A grouting hole temporarily sealed by a rubber sleeve is provided between a pair of excitation coils in the same group. The grouting inner tube is equipped with a set of openings corresponding to the grouting holes and a set of magnetic wire closed tubes corresponding to the excitation coils. The permanent magnets inside the magnetic wire closed tubes attract each other to the excitation coils, and then the permanent magnets attract the electromagnetic coils in the electromagnetic excitation valve group. The electromagnetic force generated in the external excitation coils drives the valves of the electromagnetic excitation valve group to actively open and close, thus realizing layered grouting.

[0010] The electromagnetic excitation valve assembly is detachably installed at the grouting hole section inside the grouting outer pipe. It includes a set of grouting valves arranged axially along the grout flow pipe, and each grouting valve is interconnected with the grout flow pipe. The bottom of the grouting valve is provided with a vertical flow opener that corresponds to the pipe diameter of the grout flow pipe, and its side is provided with a magnetic opening and closing device. The magnetic opening and closing device cooperates with the pile side grouting device. When the magnetic opening and closing device is not subjected to magnetic attraction, it blocks the grout. When subjected to magnetic attraction, it pushes the pile side grouting device to extend horizontally out of the corresponding rubber sleeve on the grouting hole section, thus opening the grouting mode.

[0011] The ground control unit is equipped with an addressing control module, which is used to independently control the power supply of each layer of excitation coils, so as to realize the step-by-step excitation of grouting valves at different depths.

[0012] The magnetic detection unit includes a magnetic flux sensor array evenly distributed along the longitudinal direction of the reinforcing cage and a ground data processing terminal, used to detect changes in the magnetic field caused by the magnetic slurry injected into the stratum.

[0013] Furthermore, the magnetic opening and closing device includes an electromagnetic coil and a reset spring that cooperate with each other. The pile-side grouting device has a folded structure and is connected to the end of the reset spring. When the electromagnetic coil is attracted by an external magnetic field, it pushes the reset spring, causing the pile-side grouting device to break through the rubber sleeve of the grouting outer pipe to complete the grouting.

[0014] Furthermore, a retrieval connector is fixed to the top of the electromagnetic excitation valve assembly. The retrieval connector cooperates with the retrieval and recovery device. When the valve assembly is recovered, the retrieval rod of the retrieval and recovery device is connected to the retrieval connector to complete the recovery of the grouting valve assembly.

[0015] Furthermore, the bottom of each electromagnetic excitation valve assembly is fitted with a corresponding valve seat. The bottom of the electromagnetic excitation valve assembly is provided with multi-stage plug-in bosses, and the valve seat is provided with stepped positioning slots. The multi-stage plug-in bosses and the stepped positioning slots are connected by multi-stage stepped concave-convex plug-in locking.

[0016] To further achieve the objective of this invention, a layered grouting detection method based on the above-mentioned device is also provided, the specific steps of which are as follows: S1, Installation and Positioning: Lower the assembled composite grouting pipe valve along with the steel cage to the designed depth of the pile hole, and connect the ground pipeline and the circuit. S2, Electromagnetic addressing excitation: The ground control unit sends a pulse current to the external excitation coil at the corresponding depth according to the target grouting layer. The output voltage is adjustable from 24V to 220V, generating a circumferential magnetic field, which drives the magnetic opening and closing device at that layer to work and instantly open the grouting hole. S3, Magnetic Grout Injection and Detection: The pump pumps grout mixed with magnetic particles. The grout flows out through the corresponding grouting hole opened in step S2 and is injected into the formation. At the same time, the magnetic flux sensor collects the longitudinal magnetic field distribution data of the pile body in real time to detect the grouting effect. S4, Solenoid Valve Assembly Recovery: After the grouting operation is completed and before the grout initially sets, the retrieval rod is lowered along the middle of the inner pipe of the composite grouting pipe and connected to the retrieval joint at the top of the electromagnetic excitation valve assembly. At the same time, a reverse current is applied to the excitation coil wound on the outer wall of the grouting outer pipe to enhance the magnetic force. Then, the winch is used to pull the retrieval rod to recover the valve assembly, thereby separating the valve core assembly from the pipe and pulling it back.

[0017] When recovering the solenoid valve assembly, the order is as follows: from top to bottom, the valve seat under the original solenoid valve assembly is discarded, and the solenoid actuation valve assembly and the bottom valve seat are connected by a multi-stage stepped concave-convex plug-in locking connection. As long as the retrieval rod is connected to the retrieval connector, a strong pull can disengage the solenoid actuation valve assembly from the stepped positioning groove in the bottom valve seat. This can avoid the jamming phenomenon when recovering solenoid valve assemblies in different positions.

[0018] Compared with the prior art, the advantages of the technical solution of the present invention are as follows: (1) The present invention adopts the electromagnetic drive principle to replace the passive opening mode of the traditional grouting valve that relies on the hydraulic pressure of the grouting fluid. It can realize the active excitation control of the grouting valve. Ground operators can accurately control the opening time and opening position of the grouting valve at any depth according to the construction design. It effectively avoids the pressure transmission distortion and grouting valve mis-opening in the traditional deep grouting process. It eliminates the inherent defects of the passive opening mode from the perspective of the drive principle and improves the controllability of the grouting process. (2) By injecting functional magnetic grout and arranging a magnetic flux sensor array on the grouting pipe to collect underground magnetic field signals, the original hidden underground grout flow process can be transformed into real-time observable and visualized magnetic field data, accurately determine the actual longitudinal diffusion range of the grout, and promptly identify and locate abnormal working conditions such as grout run-off and grout leakage, significantly improving the quality control level of grouting projects and providing a quantitative scientific basis for grouting effect evaluation. (3) In view of the multi-depth layered grouting requirements, the present invention has designed multiple sets of independently controlled excitation coils, which can realize addressable independent control of grouting valves at different depths. Construction personnel can flexibly select the grouting layer to be opened according to the actual situation of the target stratum, truly realize fine layered grouting, and completely avoid the phenomenon of interlayer grout flow and insufficient or excessive grouting in some layers in the traditional layered grouting process, and can ensure that each target grouting layer achieves the grouting effect required by the design. (4) The present invention designs the core drive valve body component as a recyclable structure. After the grouting operation is completed, the core component can be taken out from underground. It can be reused multiple times after one investment. Compared with the traditional one-time buried grouting valve, it greatly reduces the material procurement and construction costs. At the same time, it avoids the safety hazards of metal valve body pipeline residue interfering with subsequent engineering construction and geophysical detection signal interference, which meets the development requirements of green construction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the recyclable magnetic slurry-activated grouting pipe valve of the present invention; Figure 2 This is a schematic diagram of the electromagnetic excitation valve assembly of the present invention in the state when the valve is closed; Figure 3 This is a schematic diagram of the electromagnetic excitation valve assembly of the present invention when the valve is open; Figure 4 This is a cross-sectional view of a single grouting valve in this invention; Figure 5 This is a schematic diagram of the wiring connection of the external excitation coil of the grouting pipe according to the present invention; Figure 6 This is a cross-sectional view of a single magnetic flux sensor of the present invention; Figure 7 This is a diagram showing the arrangement of the magnetic flux sensor array in the pile body according to the present invention; Figure 8 This is a schematic diagram of the electromagnetic excitation valve assembly recovery of the present invention; Figure 9 This is a schematic diagram of the electromagnetic excitation valve assembly and valve seat of the present invention; Figure 10 This is a cross-sectional view of the magnetic wire sealing tube of the present invention; Figure 11 This is a schematic diagram of the high-speed slurry mixer of the present invention; Figure 12 This is a schematic diagram of the construction process of the layered grouting detection method of the present invention; Figure 13 This is a schematic diagram of the slurry data processing and visualization algorithm of the present invention. Detailed Implementation Example 1

[0020] To make the present invention clearer, the following description, in conjunction with the accompanying drawings, further illustrates a recyclable magnetic slurry-activated grouting pipe valve and a layered grouting detection method of the present invention. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the present invention.

[0021] See Figure 1A recyclable magnetic slurry-excited grouting pipe valve is characterized by comprising a composite grouting pipe 1, an electromagnetic excitation valve group 2, a ground control unit 3, and a magnetic detection unit 4.

[0022] (a) Composition of composite grouting pipes, such as Figure 5 As shown: Composite grouting pipe 1: Made of rigid plastic shell. Due to its strong non-magnetic properties, it can prevent the pipe body from shielding the magnetic field. The grouting pipe body can be divided into several grouting layers according to the designed grouting layer position.

[0023] Grouting hole section 111: Distributed at equal intervals along the axial direction of the grouting outer pipe 11, each grouting hole section 111 has an excitation coil 112 independently wound on its outer wall, and each pair of excitation coils 112 is provided with a grouting hole 116 temporarily sealed by a rubber sleeve 115.

[0024] Excitation coil 112: It is wound in layers on the outer wall of the grouting outer pipe 11 according to the distribution position of the magnetic wire sealing tube 22 set inside the grouting inner pipe 12, and is made of enameled copper wire. At the same time, the excitation coil 112 is provided with an epoxy resin protective layer to prevent water erosion in the soil layer and wear during grouting.

[0025] Independent leads: Each set of excitation coils 112 is connected to a pair of independent leads 113, which are led out to the ground along the conduit 114 and connected to the line integration box.

[0026] In this embodiment, the excitation coil 112 is made of QA-1 / 155 grade enameled copper round wire, which is tightly wound in layers around the outer wall of the grouting outer tube 11 corresponding to the position of the magnetic wire sealing tube 22, and is encapsulated with epoxy resin to form a waterproof, wear-resistant and insulating protective structure. The excitation coil of a single grouting layer has 300–800 turns, with 600–800 turns for deep sections ≥30m and 300–500 turns for shallow sections <30m. The conductor diameter is Φ0.5–1.2mm, with Φ0.8–1.2mm for deep drive sections and Φ0.5–0.8mm for shallow control sections. The pulse drive current is 2–10A, the holding current is 0.5–2A, the operating voltage is continuously adjustable from 24–220V, and the conventional operating voltage is 48–96V. The magnetic field strength inside the pipe wall can reach 80–300mT, and the effective magnetic field strength in the valve group working area is not less than 50mT. Each excitation coil is equipped with an independent lead-out line, which is led to the ground wiring integration box through a conduit to achieve graded independent power supply and precise control.

[0027] (ii) Electromagnetic excitation valve assembly 2: This component has a detachable inner core structure, and is inserted into the stepped positioning groove 71 on the valve seat 7 via a multi-level insertion boss 26 at the bottom. Figure 2 and Figure 9As shown. The reset spring 2122 is a 304 stainless steel compression spring with a reset force of 150-250N. It can achieve reset sealing in no more than 0.1s after power failure. The static sealing pressure is not less than 1.5MPa, and the dynamic sealing pressure is not less than 2MPa under grouting conditions. There is no leakage or backflow. The valve opening response time under pulse excitation is no more than 0.2s, and the power failure closing response time is no more than 0.1s. The valve group is equipped with a dedicated retrieval connector 24 at the top, which can quickly connect with the retrieval rod during the recovery operation.

[0028] Magnetic opening and closing device 212: See Figures 2-4 The valve body is equipped with an electromagnetic coil 2121 and a reset spring 2122. The end of the reset spring 2122 is connected to the folded pile-side grouting device 213. When a positive current is applied to the excitation coil 112, the excitation coil 112 attracts the permanent magnet 221 in the magnetic wire closed tube 22, and then the permanent magnet 221 attracts the electromagnetic coil 2121, pushing the reset spring 2122 to drive the pile-side grouting device 213 to break through the rubber sleeve 115 of the grouting outer tube 11. Thus, the electromagnetic force generated in the excitation coil 112 drives the valve of the electromagnetic excitation valve group 2 to actively open and close, realizing layered grouting.

[0029] Magnetic wire sealed tube 22: See Figure 10 The magnetic wire sealed tube 22 has a cylindrical permanent magnet 221 inside, and its exterior is covered with an epoxy resin potting layer 222.

[0030] Salvage joint 24: See Figure 2 and Figure 8 The valve body has a junction box 25 and a retrieval port at the top, which serves as a retrieval connector 24 for subsequent recovery operations; the bottom of the valve body is a fixed end. During recovery, the retrieval and recovery device 6 includes, from top to bottom, a connected winch 61, a latch 62, a retrieval rod 63, and a lifting cable 64. The lower end of the retrieval rod 63 is connected to the retrieval connector 24 to perform valve assembly recovery work. The recovery sequence is from top to bottom, and the valve seat 7 under the original solenoid valve assembly is discarded.

[0031] (III) Ground Control Unit 3: See Figure 1 It includes a power control box 31 consisting of a DC regulated power supply, a multi-channel switch controller and a current display instrument, a hub box 32, a voltage adjustment box 33 and a voltmeter 34.

[0032] (iv) Magnetic detection unit 4: See Figure 6 and Figure 7The system includes a magnetic flux sensor 411, which is longitudinally bound along the reinforcing cage 5 to form a sensor array 41. Data is transmitted to a ground data processing terminal 42 via a signal cable. The magnetic flux sensor 411 has a waterproof sealed housing 4114, which contains a magnetic flux induction coil 4111 and a high-permeability magnetic core 4112. It is encapsulated in a non-magnetic housing 4113 with epoxy resin, and has a high-temperature resistant lithium battery 4115 on the top. A pair of binding and fixing ears 4116 are provided on both sides of the housing. The magnetic flux sensor 411 is connected and fixed to the reinforcing cage 5 by passing through the binding and fixing ears 4116 with cable ties 412.

[0033] The magnetic detection unit 4 uses a high-sensitivity fluxgate sensor with a sensitivity of no more than 5nT, which can accurately identify the weak magnetic field anomalies generated by the diffusion of magnetic grout. The continuous sampling mode of the sensor has a frequency of 10-100Hz, and a sampling rate of 50Hz is used under grouting conditions. The conventional spacing of the sensor along the longitudinal direction of the reinforcing cage 5 is 1-2m, and the spacing is increased to 0.5m within 0.5m above and below the grouting layer. The ground uses a 0-500μT standard magnetic source for linear calibration, with a linear error of no more than 1%. Zero-point drift calibration is performed before lowering the sensor into the hole, and the temperature drift coefficient is no more than 0.1μT / ℃.

[0034] In addition, see Figure 1 and Figure 11 The ground data processing terminal 42 includes a computer 421, a monitor 422, a multi-functional control platform 423, and a hub box 424. The slurry is uniformly mixed by a high-speed slurry mixer 43, and then pumped by a pump 44 through a drive filter 45 to the slurry flow pipe 23. See also... Figure 11 The high-speed slurry mixer 43 includes a mixing tank 431, which is provided with a first feed inlet 432 and a second feed inlet 433. A vertical mixing shaft 434 is provided inside the mixing tank 431. The upper end of the mixing shaft 434 is connected to an external drive motor 435, which is connected to a power supply 436. A high-speed dispersing disc 437 is provided at the lower end of the mixing shaft 434.

[0035] (v) Magnetic slurry: This invention uses a magnetic grout, with ordinary cement slurry as the base liquid. The magnetic grout uses PO42.5 grade ordinary Portland cement as the base material. After preparing the ordinary cement slurry, nano-sized iron oxide powder with a particle size of 20-100 nm is added and stirred evenly in a high-speed mixer to give it strong magnetic properties. The amount of magnetic powder added is between 3% and 8% of the cement slurry volume, and the amount of high-efficiency water-reducing agent is between 0.5% and 1.0%. The saturation magnetization of the grout is not less than 15 emu / g, and the residual magnetization is not less than 3 emu / g. It has uniform and stable working performance, does not segregate, and does not clog pipes. Its standard curing 28-day compressive strength is not less than 30 MPa, ensuring sufficient grout magnetization. Ground magnetic flux sensors can clearly identify the grout diffusion range without damaging the grouting strength and mechanical properties. Nanoscale iron tetroxide powder with a particle size of 20-100nm is selected. Its particles are extremely fine, making it easy to mix into cement grout and ensuring that it does not settle, which can meet the bearing requirements of post-grouting of pile foundations. Example 2

[0036] This embodiment uses a bridge pile foundation project as an example. The pile is 50m long, and the design involves three layers of grouting at -20m, -35m, and -45m. See [link / reference] Figure 12 The specific operation steps for layered grouting using the device of the present invention are as follows: Step 1, Installation and Deployment: Connect the composite grouting pipe 1, which has three sets of excitation coils 112 wound around it, in sections, and insert the corresponding electromagnetic excitation valve groups 2 into the predetermined positions inside the pipes. Lower the composite grouting pipe 1, the excitation coil leads, and the magnetic flux sensor array 41 into the hole along with the reinforcing cage 5. Fix the pipe openings, ensuring that the leads are left with sufficient length on the ground.

[0037] Step two: Actively activate to achieve layered control: (1) Grouting at -45m of the first layer: The ground control unit 3 connects the power supply to the bottommost excitation coil 112. The ground control unit 3 outputs a voltage of 48-96V and a pulse current of 5-10A to the deepest excitation coil. The coil generates a circumferential excitation magnetic field. The electromagnetic coil 2121 in the electromagnetic excitation valve group 2 drives the folded pile side grouting device 213 to extend under the action of electromagnetic attraction, and the grouting channel is opened. The response time is ≤0.2s. The coil generates an axial magnetic field, which penetrates the pipe wall and attracts the electromagnetic coil 2121 in the valve. The electromagnetic coil 2121 moves quickly under the magnetic attraction, driving the reset spring 2122 to open the folded pile side grouting device.

[0038] (2) Grouting operation: Start pump 44 to pump magnetic grout. The grout is injected into the deep soil layer through the opened grouting hole. At this time, the ground magnetic detection terminal shows that the magnetic field strength at -45m rises sharply with the injection of grout, confirming that the grout has accurately reached the target layer.

[0039] (3) Stopping and Closing: After the grouting volume reaches the target, stop pumping and disconnect the power supply to the excitation coil. The electromagnetic coil returns to its original position in the pile-side grouting device storage box 218 under the action of the reset spring 2122, and the folded pile-side grouting device re-seals the grouting hole to prevent grout backflow. It should be noted that when closing the grouting hole, the closing response time should be ≤0.1s, and the sealing pressure should be ≥1.5MPa to prevent grout backflow.

[0040] Step 3, grouting layer by layer: According to the above logic, the ground control unit 3 sequentially connects the excitation coils 112 at -35m and -20m to achieve layered grouting from bottom to top. At the same time, the grouting valve end control line 214 in the sealing pipe 215 of the grouting valve end transmits the control signal to the vertical flow opener 211 and opens it to achieve vertical and direct flow of grout.

[0041] Step 4, Valve assembly recycling: After grouting is completed and the grout has initially set, the operator lowers the special retrieval rod 63, which has a barb at the lower end, along the inner cavity of the grouting pipe.

[0042] When the retrieval rod 63 touches the retrieval joint 24 at the top of the valve body, it is ensured to hook. At the same time, a reverse current is applied to the excitation coil 112 wound on the outer wall of the composite grouting pipe 1 to enhance the magnetic force. Then, the winch 61 pulls the retrieval rod 63 to recover the valve assembly, thereby separating the valve core assembly from the pipe and lifting it back.

[0043] Because the bottom valve seat of the solenoid valve assembly is detached from the valve core, and the valve core diameter is smaller than the inner diameter of the composite grouting pipe, the valve core can be smoothly pulled to the ground. When retrieving it, it is important to note that the retrieval sequence is from top to bottom.

[0044] During salvage operations, the rated salvage force is not less than 5kN, and the matching winch is configured with a pulling force of 10kN; the unlocking and release force of the multi-stage plug-in structure is 200-500N. The recovery is carried out in sequence from top to bottom and from shallow to deep, with a recovery success rate of not less than 98%. When using reverse excitation assistance, 100% recovery can be achieved. The overall recovery operation time for a single pile valve group is not more than 30 minutes, and the recovery time for a single valve is not more than 5 minutes. During the recovery process, the valve group and valve seat can be reliably separated. The outer diameter of the electromagnetically excited valve group is smaller than the inner diameter of the composite grouting pipe, so it can be smoothly pulled to the ground. The valve seat placement hole does not affect subsequent pile foundation construction.

[0045] Step 5, Data Extrapolation: Based on the magnetic field data collected throughout the process by the magnetic flux sensor array 41, the ground data processing terminal 42 normalizes the collected magnetic field data, retaining only the magnetic field signal. The processed data is then input into Matlab software to plot a three-dimensional magnetic field intensity-depth-time curve. Using an inversion algorithm, the diffusion radius and upward return height of the grout at each layer are calculated, generating a grouting quality inspection report. Figure 13 As shown. Example 3

[0046] In another embodiment of the present invention, the excitation coil 112 adopts a continuous wound solenoid structure, but the electromagnetic coils 2121 inside the electromagnetic excitation valve group 2 at different depths are set with different magnetic response thresholds. When the ground sends pulse currents of different intensities, only the valves corresponding to the thresholds open, thereby reducing the number of external leads and simplifying pipeline installation.

[0047] Furthermore, regarding the outflow of grout from the grouting valve, the electromagnetic coil 2121 is wound around the impermeable tank 216, and the reset spring 2122 is located inside the transmission pipe 217. The end of the reset spring 2122 near the grout flow pipe 23 can be connected to a common sealing block to seal the grout outlet, ensuring that the grout does not flow out during reset. The end of the reset spring 2122 away from the grout flow pipe 23 is connected to the pile-side grouting device 213. When force is applied, the pile-side grouting device 213 is pushed outward, opening the grout outlet and allowing the grout to flow out smoothly. Alternatively, the pile-side grouting device 213 can be matched with the pile-side grouting device receiving box 218. During reset, the two form a sealed structure to prevent grout from flowing out, and during push-out, the outlet opens to facilitate grout flow. Other common sealing and opening / closing structures can also be used in this invention.

[0048] This invention actively opens and closes valves corresponding to the target grouting layer by energizing magnetic coils at different depths. Simultaneously, before lowering the reinforcing cage, magnetic flux sensors are attached to it, forming a magnetic flux sensor array. These sensors integrate magnetic flux induction coils, and a magnetic signal detection unit detects the diffusion of magnetic grout in the soil layer. After grouting is complete, a reverse current is used to retrieve the grouting valve assembly to the ground. This not only enables precise layered grouting and detection but also allows for the recovery of the grouting valves.

[0049] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A recyclable magnetic slurry-activated grouting pipe valve, comprising a composite grouting pipe (1), an electromagnetic activation valve assembly (2), a ground control unit (3), and a magnetic detection unit (4), characterized in that: The composite grouting pipe (1) includes a non-magnetic outer grouting pipe (11) and an inner grouting pipe (12). The grouting outer pipe (11) has a set of grouting hole sections (111) distributed equidistantly along the axial direction. Each grouting hole section (111) has an excitation coil (112) independently wound on its outer wall. They are in pairs. Each set of excitation coils (112) is connected to an independent lead wire (113). The lead wire (113) is led out along the through pipe (114) and extended to the ground to connect with the ground control unit (3). A grouting hole (116) temporarily sealed by a rubber sleeve (115) is provided between a pair of excitation coils (112) in the same group. The grouting inner tube (12) is provided with a magnetic wire sealing tube (22) corresponding to the excitation coil (112), and the permanent magnet (221) inside the magnetic wire sealing tube (22) cooperates with the electromagnetic excitation valve group (2); The electromagnetic excitation valve group (2) is set directly in front of the grouting hole section (111) inside the grouting outer pipe (11). It includes a group of grouting valves (21) arranged axially along the grout flow pipe (23). Each grouting valve (21) is connected to the grout flow pipe (23). The bottom of the grouting valve (21) is provided with a vertical flow opener (211) that matches the pipe diameter of the grout flow pipe (23). The side of the valve is provided with a magnetic opening and closing device (212). The magnetic opening and closing device (212) cooperates with the pile side grouter (213). When the magnetic opening and closing device (212) is not subjected to magnetic attraction, it blocks the grout. When subjected to magnetic attraction, it pushes the pile side grouter (213) to extend horizontally out of the corresponding rubber sleeve (115) on the grouting hole section (111) and opens the grouting mode. The ground control unit (3) is equipped with an addressing control module for independently controlling the power on and off of the excitation coils of each layer; The magnetic detection unit (4) includes a magnetic flux sensor array (41) evenly distributed along the longitudinal direction of the steel cage (5) and a ground data processing terminal (42).

2. The recyclable magnetic slurry-activated grouting pipe valve according to claim 1, characterized in that: The magnetic opening and closing device (212) includes an electromagnetic coil (2121) and a reset spring (2122) that cooperate with each other. The pile side grouting device (213) has a folded structure and is connected to the end of the reset spring (2122). When the electromagnetic coil (2121) is attracted by an external magnetic field, it pushes the reset spring (2122) and drives the pile side grouting device (213) to break through the rubber sleeve (115) of the grouting outer pipe (11) to complete the grouting.

3. The recyclable magnetic slurry-activated grouting pipe valve according to claim 1 or 2, characterized in that: The top of the electromagnetic excitation valve group (2) is fixed with a retrieval connector (24). The retrieval connector (24) cooperates with the retrieval and recovery device (6). When the valve group is recovered, the bottom end of the retrieval rod (63) of the retrieval and recovery device (6) is connected to the retrieval connector (24).

4. The recyclable magnetic slurry-activated grouting pipe valve according to claim 1 or 2, characterized in that: Each electromagnetic excitation valve assembly (2) has a valve seat (7) corresponding to its bottom. The bottom of the electromagnetic excitation valve assembly (2) is provided with a multi-stage plug-in boss (26), and the valve seat (7) is provided with a stepped positioning slot (71). The multi-stage plug-in boss (26) and the stepped positioning slot (71) are connected by a multi-stage stepped concave-convex plug-in locking connection.

5. The recyclable magnetic slurry-activated grouting pipe valve according to claim 1 or 2, characterized in that: The number of turns of the excitation coil (112) is set as follows: 600~800 turns for deep sections with a burial depth ≥30m, and 300~500 turns for shallow sections with a burial depth <30m; the wire diameter of the excitation coil (112) is set as follows: Φ0.8~1.2mm for deep driving sections and Φ0.5~0.8mm for shallow control sections; the magnetic field strength inside the pipe wall reaches 80~300mT, and the effective magnetic field strength in the working area of ​​the electromagnetic excitation valve group (2) is not less than 50mT.

6. The recyclable magnetic slurry-activated grouting pipe valve according to claim 1 or 2, characterized in that: The magnetic flux sensor array (41) is a set of magnetic flux sensors (411) tied along the longitudinal direction of the steel cage (5). The data collected by the sensors is transmitted to the ground data processing terminal (42) via a signal cable. The continuous sampling mode frequency is 10-100Hz. The sampling rate is 50Hz under grouting conditions. The spacing between the sensors along the longitudinal direction of the steel cage (5) is 1-2m. The sensors are densely arranged within 0.5m above and below the grouting layer. The ground uses a 0-500μT standard magnetic source for linear calibration. The linear error is not greater than 1%. Zero-point drift calibration is performed before lowering the sensor into the hole. The temperature drift coefficient is not greater than 0.1μT / ℃.

7. The recyclable magnetic slurry-activated grouting pipe valve according to claim 1 or 2, characterized in that: The grout in the grout flow pipe (23) is a magnetic grout made of cement grout as the base liquid and mixed with magnetic particles. The magnetic particles are nano-sized iron oxide powder with a particle size of 20-100nm. The amount of magnetic powder is 3% to 8% of the amount of cement grout, the amount of high-efficiency water-reducing agent is 0.5% to 1.0% of the amount of cement grout, the saturation magnetization of the grout is not less than 15 emu / g, the residual magnetization is not less than 3 emu / g, and its standard curing compressive strength after 28 days is not less than 30MPa.

8. A method for detecting layered grouting in a recyclable magnetic slurry-activated grouting pipe valve as described in claim 3, characterized in that: S1, Installation and Positioning: Lower the assembled composite grouting pipe valve along with the steel cage to the designed depth of the pile hole, and connect the ground pipeline and the circuit. S2, Electromagnetic addressing excitation: The ground control unit (3) sends a pulse current to the external excitation coil (112) at the corresponding depth according to the target grouting layer, generates a circumferential magnetic field, drives the magnetic opening and closing device (212) of the layer to work, and instantly opens the grouting hole (116). The valve opening response time under pulse excitation is no more than 0.2s, and the power-off closing response time is no more than 0.1s. S3, Magnetic grout injection and detection: The pump pumps grout mixed with magnetic particles. The grout flows out through the corresponding grouting hole (116) opened in step S2 and is injected into the stratum. At the same time, the magnetic flux sensor array (41) collects the longitudinal magnetic field distribution data of the pile body in real time to detect the grouting effect. S4, Electromagnetic valve assembly recovery: After the grouting operation is completed, before the grout initially sets, the retrieval rod (63) is lowered along the middle position of the inner pipe of the composite grouting pipe (1) and connected with the retrieval joint (24) at the top of the electromagnetic excitation valve assembly (2). At the same time, a reverse current is applied to the excitation coil (112) wound on the outer wall of the grouting outer pipe (11) to enhance the magnetic force. Then, the retrieval rod (63) is pulled by the winch to recover the valve assembly, thereby separating the valve assembly from the pipe and pulling it back.

9. The method for detecting layered grouting of a recyclable magnetic slurry-activated grouting pipe valve according to claim 8, characterized in that: In step S4, the electromagnetic excitation valve group (2) is recovered in the order from top to bottom and from shallow to deep.

10. The method for detecting layered grouting of a recyclable magnetic slurry-activated grouting pipe valve according to claim 8, characterized in that: Based on the magnetic field data collected by the magnetic flux sensor array (41) throughout the entire process, the magnetic field data collected by the magnetic flux sensor array (41) is normalized by the ground data processing terminal (42), and only the magnetic field signal is retained. The processed data is then input into the Matlab software, and a three-dimensional curve of magnetic field strength-depth-time is plotted according to the programming. The diffusion radius and upward return height of the grout in each layer are calculated by the inversion algorithm, and a grouting quality inspection report is generated.

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