Multi-stage pressurized grouting device and method

Abstract

The application discloses a multistage pressurized grouting device, which is connected with a ground grouting station through a pipeline and comprises a buffer access module, a pressurized pumping module and a variable frequency speed regulation module. The buffer access module is communicated with the pressurized pumping module through a pipeline system, and the variable frequency speed regulation module adjusts and controls the buffer access module and the pressurized pumping module. The application also discloses a multistage pressurized grouting method. The buffer access module, the pressurized pumping module and the variable frequency speed regulation module are arranged in a well. In the case that the grouting pipeline is laid for a long distance, the slurry can be pressurized twice or even multiple times, so that the slurry can be smoothly delivered to a fire prevention and extinguishing grouting area, the liquid delivery capacity is improved, the problem of too large slurry delivery times in a shallow depth mine is solved, a double closed loop control system is designed, the phenomenon of buffer tank bursting or air suction and slurry pump body air suction is effectively avoided, constant liquid level and pressure control is realized, the probability of safety accidents is greatly reduced, and the secondary pressurization work of the slurry is ensured to be smoothly carried out.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal mine grouting, and particularly provides a multi-stage pressurized grouting device and method. BACKGROUND

[0002] The existing mine generally has a ground fixed grouting system, and due to the shallow buried coal seam and small slurry drop, as the mine is further developed, the mining area is continuously expanded, and the slurry conveying distance is further lengthened. According to statistics, the average laying distance of the slurry conveying pipeline of each production mine reaches 5000m, the slurry conveying ratio is too large, and the average slurry conveying ratio is about 25, which is much larger than the experience value of 3-8. The slurry conveying capacity of the existing grouting system has been seriously exceeded, the slurry outlet pressure is obviously insufficient, and the slurry is difficult to be effectively conveyed to the fire prevention and extinguishing grouting area. If a disaster occurs in the gob area behind the working face in the mine, due to the slurry conveying ratio problem, it is difficult to effectively take the grouting fire prevention and extinguishing technical measures at the first time, the golden time for fire extinguishing and disaster relief is easily missed, and then a huge cost will be paid. At the same time, in view of the typical characteristics of the close-range coal seam, the upper gob area is also the key area for fire prevention and control. The existing grouting system cannot achieve effective grouting on the spontaneous combustion high-risk area of the upper gob area, and therefore a multi-stage pressurized grouting device and method need to be designed. SUMMARY

[0003] To solve the above problems, the present application provides a multi-stage pressurized grouting device and method.

[0004] To achieve the above purpose, the technical solution adopted by the present application is: a multi-stage pressurized grouting device connected with a ground grouting station through a pipeline, comprising a buffer access module, a pressurized pumping module and a variable frequency speed regulation module. The buffer access module is connected with a slurry input pipe, and the pressurized pumping module is connected with a slurry output pipe. The buffer access module is communicated with the pressurized pumping module through a pipeline system. The variable frequency speed regulation module adjusts and controls the buffer access module and the pressurized pumping module.

[0005] Further, the buffer access module comprises a buffer tank and a programmable controller. The upper half of the buffer tank is a rectangular body structure, and the lower half of the buffer tank is a trapezoidal body structure. The inclination angle of the inclined surface of the buffer tank is greater than the angle of repose of loess. The distance between the slurry inlet and the slurry outlet of the buffer tank is 1.5 to 1.8 meters. The slurry inlet of the buffer tank is provided with a three-way reversing valve. The inlet of the three-way reversing valve is connected with the slurry input pipe. An input flow meter is arranged on the slurry input pipe. The middle outlet of the three-way reversing valve is communicated with the buffer tank. The overflow output port of the three-way reversing valve is connected with a first overflow pipeline. The buffer tank is internally provided with a liquid level sensor and a flow sensor. The slurry outlet of the buffer tank is provided with an outlet gate valve. The programmable controller is electrically connected with the input flow meter, the liquid level sensor, the flow sensor and the outlet gate valve.

[0006] Further, the pressurizing pumping module comprises a variable frequency speed regulation three-phase asynchronous motor and a slurry pump body, and the slurry pump body is assembled at the output end of the variable frequency speed regulation three-phase asynchronous motor, the output port of the slurry pump body is connected to one end of a three-way joint in sequence through a pipeline after passing through an electromagnetic flowmeter and a pumping check valve, the second end of the three-way joint is connected to an overflow pipeline check valve and a second overflow pipeline, the first overflow pipeline and the second overflow pipeline are connected through a metal hose, the third end of the three-way joint is connected to a slurry output pipe, and the output port of the slurry pump body and the front end of the pumping check valve are both provided with a pressure sensor.

[0007] Further, the variable frequency speed regulation module comprises a variable frequency controller, and the variable frequency controller is electrically connected with the programmable controller, the electromagnetic flowmeter, the pumping check valve, the pressure sensor and the overflow pipeline check valve.

[0008] Further, the buffer access module and the pressurizing pumping module are both provided with a steel structure chassis, the buffer tank and the programmable controller are assembled on one steel structure chassis, and the variable frequency speed regulation three-phase asynchronous motor and the slurry pump body are assembled on another steel structure chassis, a forklift loading and unloading hole is arranged on the steel structure chassis, and a protective vehicle body is assembled on the steel structure chassis.

[0009] Further, the buffer tank 1 forms a slurry buffer unit, the variable frequency speed regulation three-phase asynchronous motor and the slurry pump body form a slurry pressurizing unit, the first overflow pipeline, the second overflow pipeline and the overflow pipeline check valve form a bypass overflow unit, and the programmable controller and the variable frequency controller form a pressurized slurry multi-parameter monitoring control unit.

[0010] The multi-stage pressurized grouting method adopts the multi-stage pressurized grouting device, and specifically comprises the following steps:

[0011] Step one, the multi-stage pressurized grouting device initiates a start-up preparation, the bypass overflow unit is closed, the slurry buffer unit and the pressurized slurry multi-parameter monitoring control unit are opened;

[0012] Step two, according to the feedback signal of the liquid level sensor in the slurry buffer unit, the slurry pressurizing unit is opened, and at the same time, according to the flow feedback signal of the input flowmeter, the working flow of the slurry pump body of the slurry pressurizing unit is equivalent to the monitoring flow of the input flowmeter.

[0013] Step three, according to the feedback signals of the flow and pressure of the pressurized slurry multi-parameter monitoring control unit, the opening degree of the outlet gate valve of the pressurized slurry multi-parameter monitoring control unit and the rotating speed of the variable frequency speed regulation three-phase asynchronous motor are controlled through a double-closed-loop control system, the limit lift output under the constant flow condition of the slurry and the minimum lift value output within the limit conveying distance are performed.

[0014] Step four, when the slurry buffer unit or slurry pressurization unit fails, the PLC control box controls the slurry buffer unit, the slurry pressurization unit and the pressurized slurry multi-parameter monitoring control unit to be in a closed state; at the same time, the bypass overflow unit is in an open state, and the pressurized slurry flows into the slurry output pipe through the bypass overflow unit;

[0015] Step five, when the ground grouting station sends a shutdown signal, or the input flowmeter monitors the flow to be zero, or the slurry buffer unit liquid level is lower than the set threshold, the multi-stage pressurized grouting device initiates a shutdown preparation state, controls the variable frequency speed regulation three-phase asynchronous motor to reduce to zero, then closes the outlet gate valve and the slurry pump body, and opens the bypass overflow unit to release the residual pressure, and completes the shutdown of the pressurized device.

[0016] Further, in step three, the double closed-loop control system includes a liquid level-valve control loop and a pressure-motor speed control loop;

[0017] The liquid level-valve control loop is used to prevent the buffer tank from being blown or sucked empty, and the input flow information and liquid level information are fed back by the input flowmeter and the liquid level sensor respectively, when the liquid level is out of limit, the pressurized slurry multi-parameter monitoring control unit calculates and adjusts the opening of the outlet gate valve according to the flow information, so that the liquid level returns to the set interval;

[0018] The pressure-motor speed control loop is used to ensure the slurry conveying distance, when the liquid level information is in the set interval, the outlet pressure value of the slurry pump body is monitored in real time by the pressure sensor, and the pressurized slurry multi-parameter monitoring control unit controls the speed of the variable frequency speed regulation three-phase asynchronous motor, so that the pressure is stable;

[0019] The liquid level-valve control loop is prior to the pressure-motor speed control loop, and the pressure regulation is suspended when the liquid level is out of limit.

[0020] Further, the double closed-loop control system further includes a variable frequency speed regulation open loop flow regulation, which performs fuzzy control, specifically including:

[0021] Flow error e(k)=Q d -Q m ;

[0022] Wherein: Q d is the set target flow, unit m 3 / h; Q m is the actual flow measured by the electromagnetic flowmeter, unit m 3 / h;

[0023] Error change rate Δe(k)=e(k)-e(k-1);

[0024] Wherein: e(k-1) is the flow error of the last sampling period;

[0025] According to the preset fuzzy rule table, the motor frequency correction amount Δf(k) is inferred from the flow error e(k) and the error change rate Δe(k): Δf(k)=F[e(k), Δe(k)];

[0026] According to the motor frequency correction amount Δf(k), the motor frequency is updated: f(k+1)=f(k)+Δf(k);

[0027] Wherein: f(k) is the current motor frequency, unit: Hz; f(k+1) is the corrected motor frequency, unit: Hz.

[0028] Further, the fuzzy rule table includes language variables and control output results, the language variables include negative large, negative small, zero, positive small, positive large, and the control output results include large speed increase, medium speed increase, small speed increase, keep, small speed decrease, medium speed decrease, and large speed decrease.

[0029] The beneficial effects of using the present application are:

[0030] The application sets a buffer access module, a pressurizing pumping module and a frequency conversion and speed regulation module, which are arranged underground, and the slurry can be pressurized twice or even multiple times for long-distance slurry pipeline laying, so that the slurry can be smoothly delivered to the fire prevention and extinguishing grouting area, the liquid delivery capacity is improved, and the problem of large slurry delivery times in shallow depth mines is solved.

[0031] The application sets a buffer access module in front of the pressurizing pumping module, and a slurry anti-deposition structure is designed for the buffer tank, so that the slurry can be effectively prevented from depositing without mechanical stirring, and the smooth flow of the slurry is ensured.

[0032] The application sets a bypass overflow unit, which can continue to deliver the slurry when the slurry buffer unit or the slurry pressurizing unit fails, so that the slurry buffer unit and the slurry pressurizing unit are prevented from being further damaged, and the delivery of the slurry is ensured.

[0033] The application designs a double closed-loop control system, which can effectively prevent the buffer tank from being empty or the slurry pump body from being empty, realize constant liquid level and constant pressure control, greatly reduce the probability of safety accidents, and ensure the smooth progress of the secondary pressurization of the slurry. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a front view of the application after removing the vehicle body.

[0035] Figure 2 It is a perspective view of the slurry buffer unit of the application.

[0036] Figure 3 It is a perspective view of the slurry pressurizing unit of the application.

[0037] Figure 4 Flow chart of the double closed loop control system of the present application.

[0038] The reference signs include: 1, buffer tank, 2, programmable controller, 3, variable frequency speed regulation three-phase asynchronous motor, 4, slurry pump body, 5, frequency control. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0040] Embodiment one

[0041] With reference to Figures 1 to 3 , the multi-stage pressurized grouting device is connected with the ground grouting station through a pipeline and comprises a buffer access module, a pressurized pumping module and a variable frequency speed regulation module. The buffer access module is connected with a slurry input pipe, and the pressurized pumping module is connected with a slurry output pipe. The buffer access module is communicated with the pressurized pumping module through a pipeline system, and the variable frequency speed regulation module adjusts and controls the buffer access module and the pressurized pumping module.

[0042] The buffer access module is used for receiving slurry from an upstream and eliminating slurry pulse and flow fluctuation to provide reaction time for system adjustment.

[0043] The pressurized pumping module is used for providing power for slurry to obtain required head and flow.

[0044] The variable frequency speed regulation module is used for receiving a control signal and smoothly adjusting motor speed, so as to accurately control discharge flow and pressure of the slurry pump body 4 and realize on-demand pressurization.

[0045] Specifically, the buffer access module comprises a buffer tank 1 and a programmable controller 2. The upper half of the buffer tank 1 is a rectangular body structure, and the lower half of the buffer tank 1 is a trapezoidal body structure. The inclination angle of the inclined surface of the buffer tank 1 is greater than the angle of repose of loess. The distance between the slurry inlet and the slurry outlet of the buffer tank 1 is 1.5 to 1.8 meters. The slurry inlet of the buffer tank 1 is provided with a three-way reversing valve. The inlet of the three-way reversing valve is connected with a slurry input pipe. An input flow meter is arranged on the slurry input pipe. The middle outlet of the three-way reversing valve is communicated with the buffer tank 1. The overflow output port of the three-way reversing valve is connected with a first overflow pipeline. The buffer tank 1 is internally provided with a liquid level sensor and a flow sensor. The slurry outlet of the buffer tank 1 is provided with an outlet gate valve. The programmable controller 2 is electrically connected with the input flow meter, the liquid level sensor, the flow sensor and the outlet gate valve.

[0046] The accumulation angle of loess is 33-37 degrees, and the inclination angle of the inclined surface of the buffer tank 1 needs to be greater than the accumulation angle of loess, so that the slurry naturally slides in the buffer tank 1 to form a self-cleaning effect. Through the action of gravity and the slope guide, the slurry particles are not easy to accumulate at the bottom of the tank, and the anti-deposition function can be realized without setting a stirring device. In addition, the distance between the slurry inlet and the slurry outlet is set to 1.5-1.8 meters, which ensures that the slurry has enough flow channel in the tank, so that the flow is not short-circuited due to too short distance, and the deposition risk is not increased due to too long distance, thereby ensuring the good flow dynamics of the slurry.

[0047] The input flow meter can adopt a mine explosion-proof and intrinsic safety type electromagnetic flow meter for real-time monitoring of the upstream slurry flow.

[0048] The liquid level sensor can adopt a coal mine input type liquid level sensor, which cooperates with the flow sensor to monitor the liquid level and flow rate in the tank in real time.

[0049] The outlet gate valve can adopt a mine explosion-proof type electric outlet gate valve to control the outflow by adjusting the opening degree.

[0050] Specifically, the pressurized pumping module includes a variable frequency speed regulation three-phase asynchronous motor 3 and a slurry pump body 4, and the slurry pump body 4 is assembled at the output end of the variable frequency speed regulation three-phase asynchronous motor 3. The output port of the slurry pump body 4 is connected to one end of a three-way joint through a pipeline in sequence after an electromagnetic flow meter and a pumping check valve, a second end of the three-way joint is connected to an overflow pipeline check valve and a second overflow pipeline, and a first overflow pipeline and the second overflow pipeline are connected through a metal hose. A third end of the three-way joint is connected to a slurry output pipe, and a pressure sensor is assembled at the front end of the pumping check valve and the output port of the slurry pump body 4.

[0051] A flow meter can be further arranged on the slurry output pipe for flow detection at the final delivery end, forming a three-level monitoring system of input, middle and output to improve the closed-loop control precision.

[0052] Specifically, the variable frequency speed regulation module includes a variable frequency controller 5, and the variable frequency controller 5 is electrically connected with the programmable controller 2, the electromagnetic flow meter, the pumping check valve, the pressure sensor and the overflow pipeline check valve.

[0053] Specifically, the buffer access module and the pressurized pumping module are both provided with a steel structure chassis, the buffer tank 1 and the programmable controller 2 are assembled on one steel structure chassis, and the variable frequency speed regulation three-phase asynchronous motor 3 and the slurry pump body 4 are assembled on another steel structure chassis. A forklift loading and unloading hole is arranged on the steel structure chassis, and a protective vehicle body is assembled on the steel structure chassis.

[0054] Specifically, the buffer tank 1 forms a slurry buffer unit, the variable frequency speed regulation three-phase asynchronous motor 3 and the slurry pump body 4 form a slurry pressurization unit, the first overflow pipeline, the second overflow pipeline and the overflow pipeline check valve form a bypass overflow unit, and the programmable controller 2 and the variable frequency controller 5 form a pressurized slurry multi-parameter monitoring control unit.

[0055] Embodiment two

[0056] The multi-stage pressurized grouting method adopts the multi-stage pressurized grouting device as in Embodiment one, and specifically includes the following steps:

[0057] Step one, start-up preparation, the multi-stage pressurized grouting device initiates start-up preparation, the bypass overflow unit is closed, the slurry buffer unit and the pressurized slurry multi-parameter monitoring control unit are opened.

[0058] Step two, start-up and flow matching, according to the feedback signal of the liquid level sensor in the slurry buffer unit, the slurry pressurization unit is opened, and at the same time, according to the flow feedback signal of the input flow meter, the working flow of the slurry pump body 4 of the slurry pressurization unit is equivalent to the monitored flow of the input flow meter;

[0059] Firstly, the ground grouting station is started, the slurry flows into the device through the slurry pipeline, the input flow meter monitors the incoming slurry flow in real time, and the liquid level sensor in the buffer tank 1 monitors the liquid level in real time. When the liquid level reaches the preset safe start-up liquid level, the PLC control box 2 sends a start-up signal to the variable frequency controller 5, and the slurry pressurization unit starts;

[0060] Equivalent operation refers to the real-time output flow of the slurry pump body 4 being consistent with the input flow measured by the input flow meter, so as to avoid liquid level fluctuations caused by excessively fast or slow pump speed.

[0061] Step three, double-closed-loop intelligent regulation and control, according to the feedback signals of the flow and pressure of the pressurized slurry multi-parameter monitoring control unit, the opening degree of the outlet gate valve of the pressurized slurry multi-parameter monitoring control unit and the speed of the variable frequency speed regulation three-phase asynchronous motor 3 are controlled through a double-closed-loop control system, so as to output the limit lift under the condition of constant flow of slurry and the minimum lift value within the limit delivery distance;

[0062] The outlet gate valve is mainly used for liquid level protection, and the motor speed determines the actual lift;

[0063] Under the condition of constant flow, the limit lift is output by adjusting the speed of the variable frequency speed regulation three-phase asynchronous motor 3, the speed of the variable frequency speed regulation three-phase asynchronous motor 3 is reduced when the delivery distance is short, the minimum lift is realized, energy waste and pipeline overpressure are avoided, and the service life of the equipment is improved;

[0064] The purpose of the constant value flow is to keep the flow constant, thereby preventing the concentration stratification of the slurry, pipe deposition, and ensuring the uniformity of the fire prevention and extinguishing grouting;

[0065] As shown in the figure, the double closed-loop control system includes a liquid level-valve control loop and a pressure-motor speed control loop; Figure 4

[0066] The liquid level-valve control loop is used to prevent the buffer tank 1 from overflowing or emptying. Through the input flow meter and the liquid level sensor, the input flow information and the liquid level information are fed back respectively. When the liquid level exceeds the limit, the pressurized slurry multi-parameter monitoring control unit calculates and adjusts the opening of the outlet gate valve according to the flow information, so that the liquid level returns to the set interval;

[0067] When the liquid level is too high, the opening of the outlet gate valve is increased to speed up the discharge, and when the liquid level is too low, the opening of the outlet gate valve is reduced to slow down the discharge, so that the liquid level quickly returns to the set interval;

[0068] The pressure-motor speed control loop is used to ensure the slurry conveying distance. When the liquid level information is in the set interval, the outlet pressure value of the slurry pump body 4 is monitored in real time through the pressure sensor, and the pressure is compared with the theoretical pressure value calculated according to the target conveying distance. The speed of the variable frequency speed regulation three-phase asynchronous motor 3 is controlled and adjusted by the pressurized slurry multi-parameter monitoring control unit, so that the output pressure is stabilized at the required value, and the stability of the flow is realized;

[0069] The liquid level-valve control loop is prior to the pressure-motor speed control loop, and the pressure regulation is suspended when the liquid level exceeds the limit;

[0070] The double closed-loop control system also has double loop control. If it is necessary to quickly increase the lift, the opening of the outlet valve and the speed of the lifting motor can be increased at the same time to realize double regulation of flow and pressure, form a synergistic effect, and improve the control sensitivity.

[0071] The double closed-loop control system also includes variable frequency speed regulation open loop flow regulation. The variable frequency speed regulation open loop flow regulation performs fuzzy control, which specifically includes:

[0072] Flow error e(k)=Q d -Q m ;

[0073] Wherein: Q d is the set target flow, with units of m 3 / h; Q m is the actual flow measured by the current electromagnetic flow meter, with units of m 3 / h;

[0074] Error change rate Δe(k)=e(k)-e(k-1);

[0075] ​Wherein: e(k-1) is the flow error of the last sampling period;

[0076] According to the preset fuzzy rule table, the motor frequency correction amount Δf(k) is obtained by fuzzy inference and de-fuzzification from the flow error e(k) and the error change rate Δe(k): Δf(k)=F[e(k), Δe(k)];

[0077] According to the motor frequency correction amount Δf(k), the motor frequency is updated: f(k+1)=f(k)+Δf(k);

[0078] Wherein: f(k) is the current motor frequency, unit: Hz; f(k+1) is the corrected motor frequency, unit: Hz;

[0079] The fuzzy rule table includes language variables and control output results, the language variables include negative large, negative small, zero, positive small, and positive large, and the control output results include large speed increase, medium speed increase, small speed increase, keep, small speed decrease, medium speed decrease, and large speed decrease;

[0080] The fuzzy rule table is shown in the following table:

[0081]

[0082] Wherein, NB is set as negative large, NS is set as negative small, Z0 is set as zero, PS is set as positive small, and PB is set as positive large;

[0083] The fuzzy control takes the flow error e(k) and the error change rate Δe(k) as inputs, and the ranges of the above fuzzy terms (negative large, negative small, etc.) are defined based on the actual values of the two variables, which can be referred to the following table:

[0084]

[0085] The period in the table refers to the sampling adjustment period of the control system, which is at least 15 seconds;

[0086] Through the above fuzzy control, the device can realize the limit head output under the condition of the slurry constant flow, and can also realize the intelligent matching of a minimum head output within the limit conveying distance, so as to realize the energy-saving operation.

[0087] Step four, fault emergency treatment, when the slurry buffer unit or the slurry pressurizing unit fails, the PLC control box 2 alarms and controls the slurry buffer unit, the slurry pressurizing unit, and the pressurized slurry multi-parameter monitoring control unit to be in a closed state; at the same time, the three-way reversing valve and the overflow pipeline check valve are opened, so that the bypass overflow unit is in an open state, and the pressurized slurry flows into the slurry output pipe through the bypass overflow unit, so as to ensure that the ground grouting station does not stop and the grouting operation does not interrupt.

[0088] The faults include pump body jam, motor overload, and extremely low liquid level.

[0089] Step five, when the ground grouting station sends a stop signal, or the input flow meter monitors zero flow, or the slurry buffer unit liquid level is lower than the set threshold, the multi-stage pressurized grouting device initiates a shutdown preparation state, controls the variable frequency speed regulation three-phase asynchronous motor 3 to reduce to zero, then closes the outlet gate valve and the slurry pump body 4, opens the bypass overflow unit to release residual pressure, and completes the pressurized device shutdown;

[0090] The shutdown sequence is: a, the variable frequency speed regulation three-phase asynchronous motor 3 is reduced to zero; b, the outlet gate valve is closed; c, the slurry pump body 4 is closed; d, the bypass overflow unit is opened to release residual pressure.

[0091] The above is only a preferred embodiment of the present application. For those skilled in the art, many changes can be made to the specific implementation and application range according to the idea of the present application, as long as these changes do not deviate from the concept of the present application, and all belong to the protection scope of the present application.

Claims

1. A multi-stage pressurized grouting method using a multi-stage pressurized grouting device, characterized in that: the multi-stage pressurized grouting device comprises a buffer access module, a pressurized pumping module and a variable frequency speed regulation module, the buffer access module is connected with a slurry input pipe, and the pressurized pumping module is connected with a slurry output pipe, the buffer access module is communicated with the pressurized pumping module through a pipeline system, and the variable frequency speed regulation module adjusts and controls the buffer access module and the pressurized pumping module; the buffer access module comprises a buffer tank and a programmable controller, a three-way reversing valve is arranged at a slurry inlet of the buffer tank, an inlet of the three-way reversing valve is connected with the slurry input pipe, an input flowmeter is arranged on the slurry input pipe, a middle outlet of the three-way reversing valve is communicated with the buffer tank, an overflow output port of the three-way reversing valve is connected with a first overflow pipeline, a liquid level sensor and a flow sensor are arranged in the buffer tank, and an outlet gate valve is arranged at a slurry outlet of the buffer tank, and the programmable controller is electrically connected with the input flowmeter, the liquid level sensor, the flow sensor and the outlet gate valve; the pressurized pumping module comprises a variable frequency speed regulation three-phase asynchronous motor and a slurry pump body, the slurry pump body is arranged at an output end of the variable frequency speed regulation three-phase asynchronous motor, an output port of the slurry pump body is communicated with one end of a three-way joint through a pipeline in sequence after an electromagnetic flowmeter and a pumping check valve, a second end of the three-way joint is connected with an overflow pipeline check valve and a second overflow pipeline, the first overflow pipeline and the second overflow pipeline are communicated through a metal hose, a third end of the three-way joint is connected with the slurry output pipe, and the output port of the slurry pump body and a front end of the pumping check valve are both provided with pressure sensors; the variable frequency speed regulation module comprises a variable frequency controller, and the variable frequency controller is electrically connected with the programmable controller, the electromagnetic flowmeter, the pumping check valve, the pressure sensors and the overflow pipeline check valve; the buffer tank forms a slurry buffer unit, the variable frequency speed regulation three-phase asynchronous motor and the slurry pump body form a slurry pressurizing unit, the first overflow pipeline, the second overflow pipeline and the overflow pipeline check valve form a bypass overflow unit, and the programmable controller and the variable frequency controller form a pressurized slurry multi-parameter monitoring control unit; and the multi-stage pressurized grouting method specifically comprises the following steps: step one, the multi-stage pressurized grouting device initiates a start-up preparation, the bypass overflow unit is closed, and the slurry buffer unit and the pressurized slurry multi-parameter monitoring control unit are started; step two, according to a feedback signal of a liquid level sensor in the slurry buffer unit, the slurry pressurizing unit is started, and according to a flow feedback signal of an input flowmeter, a working flow of a slurry pump body of the slurry pressurizing unit is equivalent to a monitored flow of the input flowmeter; step three, according to feedback signals of flow and pressure of the pressurized slurry multi-parameter monitoring control unit, an opening and closing degree of an outlet gate valve of the pressurized slurry multi-parameter monitoring control unit and a rotating speed of the variable frequency speed regulation three-phase asynchronous motor are controlled through a double-closed-loop control system to perform a limit head output under a slurry constant flow condition and a minimum head output within a limit conveying distance. ​ ​ ​ ​ ​ ​ ​ ​ ​ Step four, when the slurry buffer unit or slurry pressurization unit fails, the PLC control box controls the slurry buffer unit, the slurry pressurization unit and the pressurized slurry multi-parameter monitoring control unit to be in a closed state; at the same time, the bypass overflow unit is in an open state, and the pressurized slurry flows into the slurry output pipe through the bypass overflow unit; Step five, when the ground grouting station sends a stop signal, or the input flowmeter monitors the flow to be zero, or the slurry buffer unit liquid level is lower than the set threshold, the multi-stage pressurized grouting device initiates a shutdown preparation state, controls the variable frequency speed regulation three-phase asynchronous motor to reduce to zero, then closes the outlet gate valve and the slurry pump body, and opens the bypass overflow unit to release the residual pressure, and completes the shutdown of the multi-stage pressurized grouting device.

2. The method of multi-stage pressurized grouting according to claim 1, characterized in that: The multi-stage pressurized grouting device is connected with the ground grouting station through a pipeline.

3. The method for multi-stage pressurized grouting according to claim 1, characterized in that: The upper half of the buffer tank is a rectangular body structure, and the lower half of the buffer tank is a trapezoidal body structure, the inclination angle of the inclined surface of the buffer tank is greater than the angle of repose of loess, and the distance between the slurry inlet and the slurry outlet of the buffer tank is 1.5-1.8 meters.

4. The method for multi-stage pressurized grouting according to claim 1, characterized in that: The buffer access module and the pressurized pumping module are both provided with a steel structure chassis, the buffer tank and the programmable controller are assembled on one steel structure chassis, and the variable frequency speed regulation three-phase asynchronous motor and the slurry pump body are assembled on the other steel structure chassis, a forklift loading and unloading hole is arranged on the steel structure chassis, and a protective vehicle body is assembled on the steel structure chassis.

5. The method for multi-stage pressurized grouting according to claim 1, characterized in that: In step three, the double closed-loop control system includes a liquid level-valve control loop and a pressure-motor speed control loop; The liquid level-valve control loop is used to prevent the buffer tank from being empty or being full, and the input flow information and the liquid level information are fed back by the input flowmeter and the liquid level sensor respectively, when the liquid level is out of limit, the pressurized slurry multi-parameter monitoring control unit calculates and adjusts the opening of the outlet gate valve according to the flow information, so that the liquid level returns to the set interval; The pressure-motor speed control loop is used to ensure the slurry conveying distance, when the liquid level information is in the set interval, the outlet pressure value of the slurry pump body is monitored in real time by the pressure sensor, and the pressurized slurry multi-parameter monitoring control unit controls and adjusts the speed of the variable frequency speed regulation three-phase asynchronous motor, so that the pressure is stable; The liquid level-valve control loop is prior to the pressure-motor speed control loop, and the pressure adjustment is suspended when the liquid level is out of limit.

6. The method of multi-stage pressurized grouting according to claim 5, wherein: The double closed-loop control system further includes variable frequency speed regulation open loop flow regulation, and the variable frequency speed regulation open loop flow regulation performs fuzzy control, specifically including: Flow error e(k) = Q d - Q m ; where: Q d is the setpoint flow rate in m 3 / h; Q m is the actual flow rate measured by the current electromagnetic flowmeter in m 3 / h; Error change rate Δe(k)=e(k)-e(k-1); Wherein: e(k-1) is the flow error of the last sampling period; According to the preset fuzzy rule table, the motor frequency correction amount Δf(k)=F[e(k), Δe(k)] is inferred from the flow error e(k) and the error change rate Δe(k); According to the motor frequency correction amount Δf(k), the motor frequency is updated: f(k+1)=f(k)+Δf(k); Wherein: f(k) is the current motor frequency, unit: Hz; f(k+1) is the corrected motor frequency, unit: Hz.

7. The method of multi-stage pressurized grouting according to claim 6, characterized in that: Setting language variable: the fuzzy rule table includes language variable and control output result, the language variable includes negative big, negative small, zero, positive small, positive big, the control output result includes large speed increase, medium speed increase, small speed increase, keep, small speed decrease, medium speed decrease, large speed decrease.

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