Water jet ground breaking test device and method with controllable jet time

Abstract

The invention discloses a water jet ground breaking test device and method with controllable jet time, and belongs to the technical field of geotechnical engineering test equipment. The device comprises a telescopic test bed, a test soil box, a jet flow pressure supply module, a jet flow pressure and flow real-time monitoring module and a jet flow time adjusting module. The telescopic test bench realizes accurate adjustment of the height of a nozzle through a worm and gear transmission mechanism, and the jet flow pressure supply module adopts a PID controller to maintain the pressure stable; the jet time adjusting module is a core innovative unit and triggers a double-channel signal through a time controller, a first channel drives a push-pull electromagnet to push a folding thin aluminum plate to block a jet path, and a second channel delays to close a high-pressure pump to eliminate the water hammer effect. The test method comprises the steps of soil sample preparation, jet parameter setting, time cooperative control and ground breaking data acquisition, and the wake effect is thoroughly eliminated through mechanical blocking. The problem of ground breaking depth deviation caused by pipeline residual pressure in a traditional test is solved, the device has the advantages of being high in precision and reliability, and an efficient tool is provided for water jet ground breaking mechanism research and engineering parameter calibration.

Description

Technical Field

[0001] The invention belongs to the technical field of water jet soil breaking, and in particular relates to a water jet soil breaking test device with controllable jet time. Background Art

[0002] Under the current technological background, the water jet test device has a significant technical bottleneck in controlling the jet time. That is, when the test operator decides to terminate the jet, the usual operation is to directly turn off the high-pressure pump. However, this operation method has a defect that cannot be ignored: even if the high-pressure pump has stopped working, the jet will continue to impact the soil due to the high-pressure water remaining in the pipeline. This phenomenon is also called the "wake effect." The result of the wake effect is that after the set jet time ends, the soil will still be subjected to additional impact, causing the actual jet penetration depth to be greater than the theoretical expected value. This deviation not only affects the accuracy of the test data, but also limits the application potential of water jet technology in civil engineering, geological exploration and other fields.

[0003] To address this technical problem, the present invention proposes an innovative solution designed to precisely control the jet timing and effectively eliminate the influence of the wake effect. The core of the present invention lies in the introduction of a jet timing adjustment module that can quickly and effectively block the continued impact of the water jet when the set jet timing is reached, thereby avoiding the additional impact of residual high-pressure water on the soil. Specifically, the module includes a movable blocking device that can quickly move into the path of the water jet upon receiving a control signal to achieve physical blocking of the jet. Summary of the Invention

[0004] The purpose of the present invention is to provide a water jet soil breaking test device and method with controllable jet time. Through mechanical blocking and pressure coordinated control technology, millisecond-level precise control of jet time can be achieved, the wake effect can be eliminated, and accurate soil breaking depth data under different jet times can be obtained.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A water jet soil-breaking test device with controllable jet time comprises: a retractable test bench, a test soil box, a jet pressure supply module, a jet pressure and flow real-time monitoring module, and a jet time adjustment module.

[0007] The retractable test bench consists of a vertical lift column, a horizontal crossbeam, and a dual-track dovetail guide. The vertical lift column uses a worm gear mechanism to achieve millimeter-level lifting accuracy. The horizontal crossbeam integrates an integrated laser ruler to display the distance between the waterjet nozzle and the soil surface in real time. The dual-track dovetail guide secures the slider and prevents deflection. The test soil box is fixed at the bottom of the bench, and the jet timing adjustment module is mounted at the top.

[0008] The jet pressure and flow real-time monitoring module consists of a pressure transmitter installed at the nozzle inlet and an electromagnetic flowmeter integrated in the high-pressure hose. The two transmit real-time data to the host computer through an interface to generate a pressure-flow-time curve.

[0009] The jet pressure supply module primarily consists of a high-pressure plunger pump, a water tank, a high-pressure hose, a water jet nozzle, a PID controller, and an electronically controlled proportional pressure-regulating valve. The high-pressure plunger pump draws water from the water tank and delivers it to the water jet nozzle via the high-pressure hose, creating a stable high-pressure jet. The PID controller, based on the received feedback signal, uses the electronically controlled proportional pressure-regulating valve to adjust the high-pressure plunger pump's output pressure in real time, stabilizing it at a set value.

[0010] The jet timing adjustment module includes a time controller, a push-pull electromagnet, a guide rail and slider assembly, and a foldable aluminum plate. The time controller has a built-in dual-channel output signal: the first channel drives the push-pull electromagnet, driving the foldable aluminum plate to move linearly along the guide rail; the second channel delays the high-pressure plunger pump after a certain period of time to prevent water hammer.

[0011] Furthermore, the PID controller calculates the dynamic deviation between the actual pressure value and the preset target pressure, and combines the real-time flow signal to execute a PID control algorithm with a feedforward compensation function to generate a control instruction, drives the proportional pressure regulating valve through an electrical signal to generate a corresponding valve core displacement, and linearly adjusts the output pressure of the high-pressure plunger pump, ultimately achieving rapid convergence of the jet pressure to the set value and maintaining stable control.

[0012] Furthermore, the time controller has dual channels built in, the first channel is connected to the push-pull electromagnet to control the foldable thin aluminum plate, and the second channel is connected to the power supply of the high-pressure plunger pump to control the switch of the high-pressure plunger pump.

[0013] Furthermore, the first channel of the time controller has a built-in three-stage independent timing sequence, the pressure regulation stage (T1): the electromagnet is energized, the thin aluminum plate is expanded to block water, and the pressure continues until the pressure is stable. The ground-breaking stage (T2): the electromagnet is de-energized, the thin aluminum plate is folded and moved out of the path, and T2 is exactly equal to the jet action time; the termination stage (T3): the electromagnet is energized, pushing the thin aluminum plate to expand a second time to intercept the flow.

[0014] Furthermore, the output shaft of the push-pull electromagnet and the slider are rigidly locked with a flange, and the bottom of the slider is hinged to a foldable thin aluminum plate through a universal joint to ensure that the thin aluminum plate has no lateral deflection when the electromagnet thrust is transmitted axially.

[0015] Furthermore, the foldable thin aluminum plate is made of high-strength aluminum alloy, and its unfolding angle can be adjusted to a range of 90° to 135°. The surface is provided with a guide groove of a specific depth, and the groove is designed with an optimized inclination angle to reduce water flow impact vibration.

[0016] The present invention also provides a method for supporting a water jet soil-breaking test device with controllable jet time, comprising the following steps:

[0017] (1) Fill the test soil box with soil in layers according to the preset moisture content. Adjust the vertical lifting column of the retractable test bench and use a laser ruler to accurately set the distance between the water jet nozzle and the soil surface to the preset height. Set the initial position of the foldable thin aluminum plate to the lower side of the nozzle to ensure that it does not interfere with the jet path before unfolding.

[0018] (2) Connect the water tank, high-pressure plunger pump, electronically controlled proportional pressure regulating valve, pressure transmitter, electromagnetic flowmeter, and nozzle to form a closed water circuit. After moving the nozzle to the target position, open the first and second channels of the time controller. The first channel drives the push-pull electromagnet to push the foldable thin aluminum plate along the guide rail to the jet path; the second channel turns on the power of the high-pressure plunger pump, and then dynamically adjusts the electronically controlled proportional pressure regulating valve through the PID controller to make the jet pressure reach the preset value, completing the jet stability verification.

[0019] (3) The opening time of the first channel and the closing time of the second channel are set by the time controller. The opening time of the first channel should be slightly less than the closing time of the second channel, and the opening time of the first channel is the target jet time. When the first channel is closed, the push-pull electromagnet resets, the foldable thin aluminum plate no longer blocks the water jet, and the jet begins to impact the soil surface. At the same time, the time controller starts timing.

[0020] (4) When the jet duration reaches the set value, the first channel of the time controller opens and drives the push-pull electromagnet, pushing the foldable thin aluminum plate to move along the guide rail to the jet path, physically cutting off the water flow at an angle of 90° to 135°; then the second channel of the time controller turns off the high-pressure plunger pump after reaching the preset time to avoid the water hammer effect.

[0021] (5) After the test, the accumulated water in the test soil box was extracted and gypsum solution was poured into the scouring pit. After solidification, the gypsum model was taken out to measure its three-dimensional dimensions. The actual soil breaking depth was compared with the theoretical value to calculate the error rate of the wake effect.

[0022] (6) Automatically record the jet time, pressure, flow rate and ground-breaking depth data, generate a pressure-time-ground-breaking depth correlation curve, establish a mapping relationship between the jet time and soil parameters based on the test results, and optimize the subsequent parameter settings.

[0023] The beneficial effects of the present invention are:

[0024] 1. By combining a mechanical blocking device with collaborative control logic, the water flow is physically cut off immediately when the set jet time is reached, avoiding the jet timeout problem caused by residual pressure in the pipeline in traditional methods, significantly improving the accuracy of the ground-breaking depth data, and providing a reliable experimental basis for the study of the water jet ground-breaking mechanism.

[0025] 2. The high-strength folding baffle structure and optimized diversion design can withstand the continuous impact of high-pressure water jets, effectively extending the service life of key components, while reducing the vibration interference caused by water impact, ensuring the speed and stability of the blocking action.

[0026] 3. Through modular design and dynamic parameter adjustment capabilities, it can flexibly respond to the test requirements of different soil types, layered structures and dynamic working conditions, while reducing ineffective jetting time and energy waste, achieving high efficiency and energy saving while ensuring test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the main body of the device of the present invention.

[0028] Figure 2 It is a top view of the device of the present invention.

[0029] Figure 3 This is the operation diagram of the jet time adjustment module.

[0030] Figure 1 and Figure 2 Middle: 1. Vertical lifting column, 2. Test soil box, 3. Horizontal beam, 4. Double-track dovetail groove guide rail, 5. Worm gear transmission mechanism, 6. Nozzle, 7. Electromagnetic flowmeter, 8. Pressure transmitter, 9. Computer, 10. Folding thin aluminum plate, 11. Push-pull electromagnet, 12. Time controller, 13. Electronically controlled proportional pressure regulating valve, 14. High-pressure hose, 15. High-pressure plunger pump, 16. PID controller, 17. Water tank.

[0031] Figure 3In the experiment: (1) The jet pressure and flow rate are adjusted in the early stage. At this time, the dual channels of the time controller are opened, and the push-pull electromagnet 11 pushes the folding thin aluminum plate 10 to the middle position between the nozzle 6 and the soil surface, blocking the nozzle fluid from impacting the soil surface; (2) The jet time is set through the first channel of the time controller 12, and the shutdown time of the high-pressure plunger pump 15 is set through the second channel. The first channel of the time controller 12 is closed, and then the push-pull electromagnet pulls the folding thin aluminum plate 10 away from the nozzle. Within the preset time, the fluid in the nozzle impacts the soil to form a scouring pit; (3) After the jet time is reached, the first channel of the time controller 12 is opened. After the power is turned on, the push-pull electromagnet 11 simultaneously pushes the folding thin aluminum plate 10 toward the nozzle, blocking the nozzle fluid from further impacting the soil surface. Then the second channel of the time controller 12 is closed, and the high-pressure plunger pump 15 stops running. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below with reference to the embodiments, but should not be construed as limiting the present invention:

[0033] like Figure 1 and 2 As shown: A water jet soil-breaking test device with controllable jet time, the bottom of the vertical lifting column 1 is welded by square steel, the top is welded with a threaded steel pipe, and a worm gear transmission mechanism 5 is configured for lifting the height; the test soil box 2 has a size of 50×50×50cm and is made of 50mm thick steel plate. The side walls of the box are designed as double doors, which makes it highly resistant to deformation and convenient for excavation; the double-track dovetail groove guide rail 4 is 80cm long, the guide rail shaft is made of high-carbon steel, and the bottom is supported by aluminum. The slider is ground and polished and can be fixed in any position. The nozzle 6 uses a circular nozzle with a nozzle diameter of 1.25mm; the electromagnetic flowmeter 5 uses a DN50 universal flowmeter with an applicable pressure of 0-10MPa; the pressure transmitter 8 uses a glass micro-melting core pressure transmitter, which can monitor the jet pressure of 0-20MPa; the foldable thin aluminum plate 10 is 0.8mm thick and has an unfolding angle of 90°~135°. Its surface is provided with a guide groove with a depth of 0.5mm and an inclination of 15° to reduce the impact vibration of the water flow; the push-pull electromagnet 11 has a push-pull distance of 15cm; the time controller 12 uses a pluggable dual-channel multi-functional electrical appliance with a controllable range of 0.01-999s; the high-pressure hose 14 is a 304 stainless steel corrugated pipe, 5m long and with an inner diameter of about 2cm; the electric proportional pressure regulating valve 13 has a pressure adjustment range of 0-10MPa and an adjustment accuracy of 0.02Mpa; the maximum pressure of the high-pressure plunger pump 15 is 50MPa.

[0034] Before the water jet soil breaking test, the worm gear transmission mechanism 5 is adjusted so that the target distance reaches the preset value. The dual channels of the time controller 12 are opened, and the high-pressure plunger pump 15 is started. The high-pressure plunger pump 15 pumps water from the water tank 17 and pumps it into the high-pressure hose 14, and then flows out of the nozzle 6. The PID controller 16 is turned on and the electronically controlled proportional pressure regulating valve 13 is adjusted so that the readings of the electromagnetic flowmeter 7 and the pressure transmitter 8 reach the preset jet pressure. At this time, the test is officially started. The opening time of the first channel of the time controller 12 is set to the target jet time, and the closing time of the second channel is set to the shutdown time of the high-pressure plunger pump. The first channel of the time controller 12 is closed, and the push-pull electromagnet 11 pulls the foldable thin aluminum plate 9 away from the nozzle. The fluid flowing out of the nozzle impacts the soil surface, forming a scouring pit. This process continues until the target jet time. Then the first channel of the time controller 12 is immediately opened, and the push-pull electromagnet 11 is energized at the same time. The foldable thin aluminum plate 10 returns to its initial position, blocking the water jet from continuing to impact the soil. Then the second channel of the time controller 12 is closed and the high-pressure plunger pump 15 is turned off.

[0035] Test Results: Using the test methods of the four embodiments described above, the jet depth achieved by directly shutting off the high-pressure plunger pump upon reaching the preset jet time was used as a comparative example. With all other conditions remaining the same, the resulting ground-breaking depths are shown in Table 1. The results in Table 1 demonstrate that, if the wake effect is not considered, the resulting ground-breaking depth is significantly greater than the assumed depth. This demonstrates that the experimental apparatus and test methods of the present invention can produce more realistic water jet ground-breaking test data.

[0036] Table 1

[0037]

Claims

1. A water jet soil breaking test device with controllable jet time, characterized in that: include: Retractable test bench, test soil box, jet pressure supply module, jet pressure and flow real-time monitoring module, jet time adjustment module, among which; The retractable test bench consists of a vertical lifting column, a horizontal beam and a double-track dovetail groove guide rail. The vertical lifting column adopts a worm gear transmission mechanism, the horizontal beam integrates a laser ruler, and the double-track dovetail groove guide rail fixes the slider and supports the jet time adjustment module. The jet pressure supply module includes a water tank, a high-pressure plunger pump, an electronically controlled proportional pressure regulating valve, a high-pressure hose and a water jet nozzle, which are connected in sequence. The high-pressure plunger pump dynamically adjusts the output pressure through a PID controller; The jet pressure and flow real-time monitoring module includes a pressure transmitter installed at the nozzle inlet and an electromagnetic flowmeter integrated in the high-pressure hose, both of which are connected to the host computer through an interface; The jet time adjustment module includes a time controller, a delay relay, a push-pull electromagnet, a guide rail slider assembly and a foldable thin aluminum plate; the time controller has a built-in dual-channel output signal, the first channel drives the push-pull electromagnet to push the foldable thin aluminum plate to block the jet path, and the second channel delays the shutdown of the high-pressure plunger pump.

2. The device according to claim 1, characterized in that The PID controller executes a control algorithm including a feedforward compensation function: it calculates the deviation between the actual pressure and the target pressure in real time, generates a control instruction based on the real-time flow signal of the electromagnetic flowmeter, and drives the electronically controlled proportional pressure regulating valve to linearly adjust the output pressure of the high-pressure plunger pump.

3. The device according to claim 1, characterized in that The foldable thin aluminum plate is made of high-strength aluminum alloy, and its unfolding angle can be adjusted to a range of 90° to 135°. The surface is provided with a guide groove of a specific depth, and the groove is designed with an optimized inclination angle to reduce water flow impact vibration.

4. The device according to claim 1, characterized in that The first channel of the time controller has a built-in three-stage independent timing sequence: pressure regulation stage (T1): the electromagnet is energized, the thin aluminum plate is expanded to block water, and the pressure continues until the pressure is stable; ground breaking stage (T2): the electromagnet is de-energized, the thin aluminum plate is folded and moved out of the path, and T2 is exactly equal to the jet action time; termination stage (T3): the electromagnet is energized, pushing the thin aluminum plate to expand a second time to intercept the flow.

5. A water jet soil breaking test method with controllable jet time, based on the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Fill the test soil box with soil in layers and compact it, and adjust the retractable test stand so that the nozzle spacing reaches the preset height; (2) Connect the water circuit and pre-adjust the jet pressure to the set value to complete the jet stability check; (3) Set the target jet time and blocking delay time, and start the jet to impact the soil surface; (4) When the jet time reaches the target jet time, the foldable thin aluminum plate is triggered to block the jet path, and the high-pressure plunger pump is turned off after the delay time is reached; (5) When the pressure drops to a safe threshold, the foldable thin aluminum plate is retracted and the groundbreaking data is collected and analyzed.

6. The method according to claim 5, characterized in that In step (5), the scour pit shape is obtained by using the gypsum pouring and solidification method.

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