A pressure self-control device for static load test of a foundation pile and a control method thereof

Abstract

The application discloses a pressure self-control device for a static load test of a foundation pile and a control method thereof. The pressure self-control device for the static load test of the foundation pile can automatically pressurize or depressurize according to a real-time pressure value, and realizes automatic operation in the whole process. Meanwhile, in the control method, different pressure control stages are determined according to a conversion result of an actual pressure value and a target pressure value, and the rotation speed of a driving unit is correspondingly adjusted to accurately adjust the oil outlet speed of hydraulic oil of an oil pump, so that the pressure self-control device realizes stepwise pressurization and stepwise depressurization, and the efficient and accurate pressure control is realized.

Description

Technical Field

[0001] This invention relates to the field of building foundation pile testing equipment, specifically to a pressure self-control device and its control method for static load testing of foundation piles. Background Technology

[0002] The principle of the static load test for foundation piles is as follows: Figure 1 As shown, after foundation pile 2 is built in soil layer 1, to test the bearing capacity of foundation pile 2, a load support frame 3 is first built on the ground around foundation pile 2. Then, the maximum load 4 required for the test (the load is generally composed of sandbags or stones) is piled on the load support frame 3. A hydraulic jack 5 is placed between foundation pile 2 and load 4 (the hydraulic jack 5 should be placed at the center of the top surface of the foundation pile). By changing the distribution of oil in the hydraulic jack 5, the top of the hydraulic jack 5 is extended outward to provide support force to the load 4. The longer the top of the hydraulic jack 5 extends, the greater the support force provided to the load 4. Similarly, the shorter the top of the hydraulic jack 5 extends, the smaller the support force provided to the load 4. Since the hydraulic jack 5 is located between foundation pile 2 and load 4, the support force provided by the hydraulic jack 5 to the load 4 is equal to the pressure on the foundation pile. By applying different pressures to the foundation pile and holding them for the required time, the displacement of the foundation pile relative to the soil layer is measured, thereby determining the bearing capacity of the foundation pile. Based on this principle, there are currently various pressure control devices for static load testing of foundation piles, but none of them can achieve both high efficiency and accuracy in the test.

[0003] Currently, the main pressure control techniques used for static load testing of foundation piles are manual pressure application and depressurization methods and electric hydraulic pump pressure application and depressurization methods.

[0004] 1. Manual Pressure Application and Relief Method: This method uses a hydraulic jack in conjunction with a manual pump. When pressurizing the foundation pile, the valve is locked, and the lever of the manual pump is cranked up and down. The manual pump forces hydraulic oil from the oil tank into the hydraulic jack. The hydraulic jack's inlet is equipped with a one-way valve, allowing hydraulic oil to enter the jack but not exit. The increased oil volume in the hydraulic jack pushes the jack's jack head outward, increasing the load pressure. The real-time pressure provided by the hydraulic jack is read from the pressure gauge on the jack. When depressurizing the foundation pile, the valve is loosened, and the hydraulic oil in the hydraulic jack flows back into the oil tank. The decrease in hydraulic oil in the hydraulic jack correspondingly reduces the pressure provided to the load.

[0005] This device is simple in structure, easy to operate, and inexpensive, but it has many problems: a) Manual pressurization requires a lot of manpower and is inefficient. The test pressure value and pile displacement value are all recorded manually, which is prone to large errors; b) Depressurization is difficult to control and is prone to being depressurized too quickly, resulting in excessive depressurization and the need to manually pressurize again; c) The speed of rocking the lever during pressurization and the degree to which the unloading valve is loosened during depressurization depend entirely on the operator's experience, making it difficult to meet the pressure control accuracy.

[0006] 2. Electric Hydraulic Pump Pressure Adjustment Method: This method uses an electric hydraulic pump to replace manual pressure adjustment. For easier pressure control, a control box for the electric hydraulic pump and a computer for sending pressure adjustment commands are required. The hydraulic pump unit has a T-junction at the reservoir interface, controlled synchronously by a reversing switch. When the reversing switch is in pressurization mode, hydraulic oil flows into the lower tank of the hydraulic jack through the outlet pipe, while hydraulic oil in the upper tank flows back to the reservoir through the return pipe. When the reversing switch is in depressurization mode, hydraulic oil flows into the upper tank of the hydraulic jack through the return pipe, while hydraulic oil in the lower tank flows back to the reservoir through the outlet pipe. One-way valves on the outlet and return pipes prevent reverse flow of hydraulic oil into the pump. A pressure sensor connected to the outlet pipe measures the pressure of the hydraulic oil in the lower tank in real time and feeds this pressure back to the computer, which then controls the pump operation based on the pressure value.

[0007] While the aforementioned pressure control device enables real-time monitoring of pressure values, with both pressurization and depressurization controlled by a computer, simplifying the testing process and offering greater reliability compared to manual pressurization and depressurization methods, it also presents the following problems: a) A reversing switch is installed on the electric oil pump. When reversing pressurization and depressurization, the switch needs to be manually activated. If the operator forgets to activate the switch, the jack may continue to pressurize during depressurization, affecting the experiment and potentially even overturning the load platform; b) Based on different oil output speeds, oil pumps can be broadly categorized into high-flow-rate pumps and low-flow-rate pumps. With a high-flow-rate pump, after the pump motor stops at the target pressure or depressurization value, the actual pressure value often exceeds the target value significantly, failing to meet accuracy requirements. With a low-flow-rate pump, the pressure control value is more precise, but the low efficiency means that pressurization and depressurization require a longer time during high-load experiments.

[0008] In summary, the manual pressure control method relies entirely on human labor, resulting in inaccurate pressure control and low efficiency. The electric hydraulic pump pressure control method requires manual reversing, which is cumbersome. Different flow rate electric hydraulic pumps offer varying levels of control accuracy and efficiency, failing to achieve both precision and high efficiency. For static load tests of different tonnages, pumps with different flow rates are required to meet accuracy requirements. Therefore, given the technical limitations of existing pressure self-control devices for pile static load tests, there is an urgent need to develop a pressure self-control device that is easy to operate and can achieve both high efficiency and accuracy. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in the prior art by providing a pressure self-control device for static load testing of foundation piles that is easy to operate, fully automated, and has high and accurate pressure control efficiency. This pressure self-control device can automatically switch between pressurization and depressurization modes based on real-time pressure values, achieving fully automated operation. Furthermore, in terms of control method, different pressure control stages are determined based on the conversion results of real-time and target pressure values. Correspondingly, the rotational speed of the drive unit is adjusted to change the hydraulic oil output speed of the oil pump, achieving staged pressurization and staged depressurization of the pressure self-control device, thus balancing pressure control efficiency and accuracy.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A pressure self-control device for static load testing of foundation piles includes a control unit, a valve assembly, a drive unit, a power supply, a detection unit, an oil tank, an oil outlet pipe, an oil return pipe, and an execution unit. The valve assembly includes a loading valve and an unloading valve. The drive unit, the detection unit, the loading valve, and the unloading valve are all connected to the control unit. The output end of the drive unit is connected to the input end of an oil pump, and the drive unit drives the oil pump to rotate synchronously. The control unit controls the rotational speed of the drive unit. One end of the oil pump inlet pipe is connected to the oil tank, and the other end of the inlet pipe... The device can be selectively connected to the oil outlet pipe and the oil return pipe; the oil outlet pipe is connected to the oil inlet end of the execution unit, and an oil outlet branch is connected to the oil outlet pipe, which is connected to the oil storage tank through an unloading valve; the oil return pipe is connected to the oil outlet end of the execution unit, and a oil return branch is connected between the oil return pipe and the execution unit, which is connected to the oil storage tank through a loading valve; the detection unit is installed on the oil outlet pipe for real-time measurement of the oil pressure in the oil outlet pipe; the power supply provides electrical energy to the device.

[0012] Specifically, the drive unit is a DC motor, and the oil pump is a high-flow oil pump.

[0013] Specifically, the oil pump is equipped with a three-way valve, through which the oil inlet pipe can be selectively connected to the oil outlet pipe or the oil return pipe, and the actuator is a hydraulic jack.

[0014] Furthermore, a first check valve is installed on the oil outlet pipe between the three-way valve and the hydraulic jack, which prevents hydraulic oil from flowing back into the oil pump outlet; a second check valve is installed on the oil return pipe between the three-way valve and the hydraulic jack, which prevents hydraulic oil from flowing back into the oil pump outlet.

[0015] Specifically, the detection unit is configured as an oil pressure sensor, the oil outlet pipe is connected to the branch of the oil outlet pipe through a tee connector, and the oil pressure sensor is installed on the tee connector.

[0016] Furthermore, a motor speed control module is provided on the control unit, which can adjust the speed of the drive unit.

[0017] This invention uses a DC motor oil pump, which is designed for high flow rates. A control unit is installed on the oil pump to adjust the speed of the DC motor, thereby changing the oil pump's output speed. Furthermore, loading and unloading valves are installed on the oil pump's outlet and return pipes, both connected to the control unit. The control unit controls the opening and closing of the loading and unloading valves, enabling the pressure self-control device of this invention to automatically switch between pressure-adding and unloading modes based on real-time pressure values ​​and automatically adjust the pressure-adding and unloading speeds, achieving fully automated operation.

[0018] The present invention also provides a control method for the above-mentioned pressure self-control device, including the following steps:

[0019] Step 1: Obtain the target pressure value F d Parameter information; the control unit reads the pressure value of the detection unit in real time and calculates the real-time pressure value F of the execution unit based on the conversion factor of the execution unit. t ;

[0020] Step 2: Determine the pressurization or depressurization mode;

[0021] Step 3: Based on the calculation results of formula (1), determine the control stage for pressurization or depressurization, and perform staged pressurization or depressurization operations. During the execution process, continuously acquire real-time pressure values.

[0022]

[0023] Where B is the ratio of the error between the real-time pressure value and the target pressure value to the target pressure value;

[0024] Step 4: Maintain the target pressure value F dThe time required to maintain the real-time pressure value F t Within the specified threshold e of the target pressure value F d If it is not within the specified threshold e, repeat step three; if it is within the specified threshold e, maintain the real-time pressure value F t Within the specified threshold e.

[0025] According to the real-time pressure value obtained by the detection unit and the result of conversion of the target pressure value, the present invention determines the pressurization and depressurization modes and determines different pressure control stages, correspondingly adjusts the rotation speed of the drive unit to change the oil output speed of the oil pump hydraulic oil, so that the pressure self-control device can automatically perform staged pressurization or staged depressurization, achieving both pressure control efficiency and accuracy; at the same time, by detecting the pressure situation in the execution unit in real time, automatically performing precise pressurization or depressurization operations on the pressure values exceeding the accuracy range, so as to ensure that the real-time pressure value and the target pressure value always remain within the required accuracy range, greatly improving the test efficiency and the accuracy of the test results.

[0026] Specifically, when B < 0, open the loading valve, and the control unit controls the pressure self-control device to perform staged pressurization; when B > 0, open the unloading valve, and the control unit controls the pressure self-control device to perform staged depressurization.

[0027] Specifically, the staged pressurization or staged depressurization operations are as follows:

[0028] When B ≤ -20% or B ≥ 20%, modulate the drive unit to rotate at full speed, and read the real-time pressure value F at regular intervals t , and use the current real-time pressure value F t(n+1) Subtract the previous real-time pressure value F tn to obtain the pressure change rate n is a natural number greater than or equal to 1; calculate a certain number of pressure change rates and calculate the first average pressure change value As the real-time pressure value F t is continuously read, continuously update the full-speed average pressure change value D with the first average pressure change value ; 全 ;

[0029] When -20% < B ≤ -10% or 10% ≤ B < 20%, keep the corresponding valve open, and modulate the drive unit to rotate at half speed. Calculate the second average pressure change value when the drive unit rotates at half speed in the same way as in step 1 and calculate the first average pressure change value according to calculation formula (s) and the second average pressure change value to update the full-speed average pressure change value D according to the result of the average value 全 ,

[0030]

[0031] When -10% < B < -|e| or |e| < B < 10%, the rotational speed of the driving unit is set according to the calculation formula (3).

[0032]

[0033] Where:

[0034] V is the rotational speed of the driving unit.

[0035] F d is the target pressure value, V 全 is the speed value when the driving unit rotates at full speed.

[0036] ││ represents the absolute value.

[0037] e represents the specified threshold value.

[0038] When -|e| ≤ B ≤ |e|, the driving unit stops working, the loading valve and the unloading valve are closed, the driving unit stops rotating, and the pressure value at this time is maintained; if during the maintenance process, -10% < B < -|e|, the loading valve is opened, and the driving unit is started to pressurize at the rotational speed obtained from the calculation formula (3); if during the maintenance process, 10% > B > |e|, the unloading valve is opened, and the driving unit is started to depressurize at the rotational speed obtained from the calculation formula (3).

[0039] In order to achieve the accuracy and efficiency of the pressurization process, specifically, the step-by-step pressurization includes the following steps:

[0040] When B ≤ -20%, the loading valve is opened, the driving unit is adjusted to rotate at full speed, and the real-time pressure value F is read every certain period of time. t , the current real-time pressure value F t(n+1) minus the previous real-time pressure value F tn to obtain the pressure change rate. n is a natural number greater than or equal to 1. Every certain number of pressure change rates are calculated. Then the first average pressure change value is calculated. As the real-time pressure value F t is continuously read, the first average pressure change value is continuously used. to update the full-speed average pressure change value D. 全 ;

[0041] As the pressurization continues, when - |20%| < B ≤ -10%, the loading valve is kept open at this time, and the driving unit is adjusted to rotate at half speed. Similar to step 1, the second average pressure change value when the driving unit rotates at half speed is calculated. Calculate the first average pressure change value according to calculation formula (2). And the average value of the second average pressure change value The full-speed average pressure change value D is updated according to the result of the average value 全 ;

[0042] As the pressurization continues, when -10% < B < -|e|, the rotational speed of the drive unit is set according to calculation formula (3).

[0043] As the pressurization continues, when -|e| ≤ B ≤ |e|, the drive unit is stopped, the loading valve is closed, the rotation of the drive unit is stopped, and the current real-time pressure value is maintained within this range according to the time required for the target pressure value; if during the maintenance process, 10% > B > |e|, the unloading valve is opened, and the drive unit is started at the rotational speed obtained by calculation formula (3) for pressure relief.

[0044] To achieve the accuracy and efficiency of the pressure relief process, specifically, the step-by-step pressure relief includes the following steps:

[0045] When B ≥ 20%, the unloading valve is opened, the drive unit is adjusted to rotate at full speed, and the real-time pressure value F is read every certain interval t , using the current real-time pressure value F t(n+1) Subtract the previous real-time pressure value F tn To obtain the pressure change rate n is a natural number greater than or equal to 1; every certain number of pressure change rates are calculated And calculate the first average pressure change value As the real-time pressure value F t Is continuously read, the full-speed average pressure change value D is continuously updated with the first average pressure change value ; 全 ;[[ID=X]] [[ID=Y]]

[0046] As the pressure relief continues, when 10% ≤ B < 20%, the unloading valve is kept open at this time, and the drive unit is adjusted to rotate at half speed. Similarly to step 1, calculate the second average pressure change value when the drive unit rotates at half speed And calculate the first average pressure change value according to calculation formula (2) And the average value of the second average pressure change value The result of the average value is used to update the full-speed average pressure change value D full;

[0047] As the pressure relief continues, when |e| < B < 10%, the rotational speed of the drive unit is set according to calculation formula (3);

[0048] As the pressure relief continues, when -|e| ≤ B ≤ |e|, the drive unit stops working, the unloading valve is closed, and the drive unit stops rotating. The current real-time pressure value is maintained within this range according to the time required for the target pressure value. If during the maintenance process, -10% < B < -|e|, the loading valve is opened, and the drive unit is started to pressurize at the rotation speed obtained from formula (3).

[0049] Further, in step two, the control terminal (such as a computer or mobile phone) sends a pressurization or pressure relief instruction. If the control instruction sent by the control terminal does not match the actual situation, the control unit compares with the specified threshold e according to formula (1), and controls the pressure automatic control device to perform pressurization or pressure relief operations.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] 1. The present invention uses a large-flow pressure automatic control device, combined with an innovative pressure control method, which can automatically adjust the control strategy and control stage according to the result of converting the real-time pressure value and the target pressure value, and correspondingly adjust the rotation speed of the DC motor to change the oil output speed of the oil pump, realizing the automatic step-by-step pressurization and step-by-step pressure relief of the pressure automatic control device, achieving both the pressure control efficiency and accuracy; at the same time, by detecting the pressure situation in the execution unit in real time, accurate pressurization or pressure relief operations are automatically performed on the pressure value exceeding the accuracy range, so as to ensure that the real-time pressure value remains within the accuracy range specified by the target pressure value, greatly improving the test efficiency and the accuracy of the test results.

[0052] 2. The pressure automatic control device of the present invention has a simple structure and is very convenient for on-site installation; the pressure control process is fully automated without manual intervention, and the control process is sent to the upper computer such as a mobile phone or computer for monitoring in real time, and the operation process is convenient and fast.

[0053] 3. The present invention can be powered by a storage battery, which can meet the harsh working environments such as no power or power outage at the static load test site. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the working principle of the pressure automatic control device in the prior art;

[0055] Figure 2 It is a schematic diagram of the overall structure of the pressure automatic control device in the first embodiment of the present invention;

[0056] Figure 3 It is a schematic diagram of the pressurization process of the pressure automatic control device in the first embodiment of the present invention;

[0057] Figure 4 It is a schematic diagram of the pressure relief process of the pressure automatic control device in the first embodiment of the present invention;

[0058] Figure 5 This is a flowchart of the control method for the pressure self-control device in Embodiment 2 of the present invention;

[0059] Figure 6 This is a flowchart illustrating the pressurization process control method of the two-pressure self-control device according to the present invention.

[0060] Figure 7 This is a flowchart of the pressure relief process control method of the two-pressure self-control device according to the present invention;

[0061] In the diagram: 1. Soil layer; 2. Foundation pile; 3. Load support frame; 4. Load; 5. Hydraulic jack; 6. Power supply; 7. Oil tank; 8. DC motor; 9. Oil pump; 10. Three-way valve; 11. Second check valve; 12. Unloading valve; 13. Loading valve; 14. First check valve; 15. Oil outlet branch; 16. Oil return pipeline; 17. Oil outlet pipeline; 18. Oil pressure sensor; 19. Control unit. Detailed Implementation

[0062] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] Example 1

[0064] like Figure 2As shown, this embodiment provides a pressure self-control device for static load testing of foundation piles, including a control unit 19, a valve assembly, a drive unit, a power supply unit 6, a detection unit, an oil tank 7, an oil outlet pipe 17, an oil return pipe 16, and an execution unit. The valve assembly includes a loading valve 13 and an unloading valve 12. The drive unit, the detection unit, the loading valve 13, and the unloading valve 12 are all communicatively or electrically connected to the control unit 19. The output end of the drive unit is connected to the input end of the oil pump 9, and the drive unit drives the oil pump 9 to rotate synchronously. The control unit 19 controls the rotational speed of the drive unit. One end of the oil inlet pipe of the oil pump 9 is connected to the oil tank 7. The other end of the oil inlet pipe can be selectively connected to the oil outlet pipe 17 and the oil return pipe 16; the oil outlet pipe 17 is connected to the oil inlet end of the execution unit, and an oil outlet pipe branch 15 is connected to the oil outlet pipe 17. The oil outlet pipe branch 15 is connected to the oil storage tank 7 through an unloading valve 12; the oil return pipe 16 is connected to the oil outlet end of the execution unit, and an oil return pipe branch is connected between the oil return pipe 16 and the execution unit. The oil return pipe branch is connected to the oil storage tank 7 through a loading valve 13; the detection unit is installed on the oil outlet pipe 17 to measure the oil pressure in the oil outlet pipe in real time; the power supply 6 provides electrical energy to the device.

[0065] Preferably, both the loading valve 13 and the unloading valve 12 can be electromagnetic valves, which are convenient to control and have high stability.

[0066] Specifically, the drive unit is a DC motor 8, the oil pump 9 is equipped with a three-way valve 10, and the oil inlet pipe can be selectively connected to the oil outlet pipe 17 or the oil return pipe 16 through the three-way valve 10. The execution unit is a hydraulic jack 5.

[0067] Furthermore, a first check valve 14 is installed on the oil outlet pipe 17 between the three-way valve 10 and the hydraulic jack 5. The first check valve 14 prevents hydraulic oil from flowing back into the oil outlet of the oil pump 9. A second check valve 11 is installed on the oil return pipe 16 between the three-way valve 10 and the hydraulic jack 5. The second check valve 11 can prevent hydraulic oil from flowing back into the oil outlet of the oil pump 9.

[0068] Specifically, the detection unit is set as an oil pressure sensor 18, the oil outlet pipe 17 is connected to the oil outlet pipe branch 15 through a tee connector, and the oil pressure sensor 18 is installed on the tee connector.

[0069] Specifically, the control unit 19 is communicatively or electrically connected to the DC motor 8. The control unit 19 is equipped with a motor speed control module, which can adjust the speed of the DC motor 8. The shaft of the DC motor 8 and the shaft of the oil pump 9 are fixedly connected by fasteners (such as screws), so that when the DC motor 8 rotates, it drives the oil pump 9 to rotate synchronously. The oil inlet of the oil pump 9 is connected to the oil reservoir 7, which contains hydraulic oil. When the oil pump 9 rotates, the hydraulic oil in the oil reservoir 7 flows into the oil pump 9. The oil pump 9 is equipped with a three-way valve 10, which selectively directs hydraulic oil into the outlet pipe 17 or the return pipe 16. The outlet pipe 17 is connected to the lower oil tank connector of the hydraulic jack 5, and the return pipe 16 is connected to the upper oil tank connector of the hydraulic jack 5. A first check valve 14 is installed on the outlet pipe 17 between the three-way valve 10 and the hydraulic jack 5 to prevent hydraulic oil from flowing back into the outlet of the oil pump 9. A second check valve 11 is installed on the return pipe 16 between the three-way valve 10 and the hydraulic jack 5 to prevent hydraulic oil from flowing back into the outlet of the oil pump 9. An outlet pipe branch 15 is connected to the outlet pipe 17 between the first check valve 14 and the hydraulic jack 5. The outlet pipe branch 15 is connected to the oil storage tank 7, and an unloading valve 12 is installed on the outlet pipe branch 15. A return oil branch is connected to the return oil pipe 16 between the second one-way valve 11 and the hydraulic jack 5. The return oil branch is connected to the oil storage tank 7, and a loading valve 13 is installed on the return oil branch. Both the loading valve 13 and the unloading valve 12 are solenoid valves and are either communicatively or electrically connected to the control unit 19. A tee connector is installed on the oil outlet pipe 17 between the first one-way valve 14 and the hydraulic jack 5. The oil pressure sensor 18 can be tightened onto the tee connector. The oil pressure sensor 18 is communicatively connected to the control unit 19. The oil pressure sensor 18 measures the hydraulic oil pressure in the oil outlet pipe 17 in real time and feeds the pressure value back to the control unit 19. The control unit 19 is equipped with a microprocessor unit, which can calculate the real-time load pressure on the hydraulic jack 5 based on the real-time pressure value and the conversion factor of the hydraulic jack 5. The power supply 6 (which can be a battery or other form of power supply) is electrically connected to the control unit 19. The control unit 19 is equipped with a power conversion circuit, which converts the electrical energy provided by the power supply 6 into various power supplies required by the device.

[0070] The control unit 19 is equipped with a wireless communication module, which can receive the target pressure value and the duration of maintaining that pressure from a control terminal (e.g., a mobile phone or computer) via wireless signals. The wireless communication module can use a communication frequency of 433MHz. The control unit 19 calculates the real-time pressure value and determines whether to pressurize or depressurize based on the difference between the real-time pressure value and the target pressure value.

[0071] like Figure 3As shown, when pressurization is applied, the three-way valve 10 is connected to the oil outlet pipe 17, and the loading valve 13 is opened. Then, the DC motor 8 is started. The DC motor 8 rotates and drives the oil pump 9 to draw in oil. At this time, the hydraulic oil flows into the lower oil tank of the hydraulic jack 5 through the oil outlet pipe 17. The oil volume in the lower oil tank of the hydraulic jack 5 increases, and the liquid pressure in the lower oil tank increases, pushing the top of the hydraulic jack 5 to extend outward. The hydraulic oil in the upper oil tank of the hydraulic jack 5 is squeezed and flows out through the return oil pipe 16. At this time, the loading valve 13 is opened, and the hydraulic oil flows back to the oil storage tank 7 through the loading valve 13.

[0072] like Figure 4 As shown, when depressurization occurs, the three-way valve 10 is connected to the return oil pipe 16, and the unloading valve 12 is opened. Then, the DC motor 8 is started. The DC motor 8 rotates and drives the oil pump 9 to draw in oil. At this time, the hydraulic oil flows into the upper oil tank of the hydraulic jack 5 through the return oil pipe 16. The oil volume in the upper oil tank of the hydraulic jack 5 increases, and the liquid pressure in the upper oil tank increases, pushing the top of the hydraulic jack 5 to contract inward. The hydraulic oil in the lower oil tank of the hydraulic jack 5 is squeezed and flows out through the oil outlet pipe 17. At this time, the unloading valve 12 is opened, and the hydraulic oil flows back to the oil storage tank 7 through the unloading valve 12.

[0073] Furthermore, the control unit 19 includes a memory for storing program code and various data. The memory can be configured as a read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), or any other computer-readable storage medium capable of carrying or storing data.

[0074] The control unit 19 may take the form of a combination of one or more central processing units (CPUs), MPUs, microprocessors, digital processing chips, and various control chips. The control unit 19 connects to the DC motor 8, the unloading valve 12, the loading valve 13, and the detection unit through various interfaces and lines. The control unit 19 runs or executes programs or modules stored in the memory of the control unit 19 and stores the data during the execution process. By calling the data stored in the memory, the control unit 19 can control the opening and closing of the DC motor 8, the unloading valve 12, and the loading valve 13, and meet the data processing needs of the control unit 19.

[0075] Furthermore, the control unit 19 is wirelessly connected to the control terminal. Preferably, the control terminal can be a wireless remote control or a mobile terminal (such as a smartphone or smart tablet). A wireless communication module is connected to the connection interface (such as a USB interface) on the control terminal to communicate wirelessly with the control unit 19. The control terminal is equipped with static load testing software commonly used in the prior art (the static load testing software here is software commonly used in the field, and only needs to meet the requirements of this invention). Before starting the static load test, the test specifications, loading levels, unloading levels, and maximum target pressure value are selected in the static load testing software. Then, the static load testing software automatically sends pressurization or depressurization commands. The pressure self-control device for the static load test of the foundation pile receives the command information and automatically performs pressurization or depressurization operations.

[0076] Example 2:

[0077] The present invention also provides a control method for the pressure self-control device of Embodiment 1, such as... Figure 5-7 As shown. Static load testing software is installed on the control terminal (mobile phone or computer). Before starting the static load test, the test specifications, loading stages, unloading stages, and target pressure value F are selected in the static load testing software. d Based on parameters such as pressure value, the control unit 19 automatically switches between pressurization and depressurization modes, and adjusts the speed of the DC motor 8 and the hydraulic oil output speed of the oil pump 9 according to different pressure control stages, thereby automatically adjusting the pressurization and depressurization speed. This invention's control method requires no manual operation throughout the entire process, greatly improving testing efficiency and achieving extremely high pressure control accuracy, thus balancing pressure control efficiency and precision. The control process of this invention is as follows:

[0078] Step 1: The control unit 19 reads the pressure value of the detection unit in real time and calculates the real-time pressure value F of the execution unit according to the conversion factor of the execution unit. t ;

[0079] Step 2: Determine the pressurization or depressurization mode;

[0080] Step 3: Based on the calculation results of formula (1), determine the control stage for pressurization or depressurization, and perform staged pressurization or depressurization operations. During the execution process, continuously acquire real-time pressure values.

[0081]

[0082] Where B is the ratio of the error between the real-time pressure value and the target pressure value to the target pressure value;

[0083] Step 4: Maintain the target pressure value F d The required time to maintain the real-time pressure value F tWithin the specified threshold e: -|e|≤B≤|e|: If not within the specified threshold e, repeat step three; if within the specified threshold e, maintain the real-time pressure value F. t Within the specified threshold e range.

[0084] The threshold 'e' represents the allowable error range, or accuracy, which can be customized according to actual working conditions or can adopt industry-standard error range values.

[0085] Through the above control method, different pressure control stages can be determined based on the difference between the real-time pressure value and the target pressure value. This enables the pressure self-control device to automatically perform graded pressurization or graded depressurization, thereby improving the efficiency of pressurization and depressurization and achieving precise pressure control. At the same time, the pressure in the hydraulic jack 5 can be detected in real time. For pressure values ​​that exceed the accuracy range, automatic and precise pressurization and depressurization operations can be performed according to the control method, thereby ensuring that the actual pressure value and the target pressure value remain within a certain accuracy range, greatly improving the testing efficiency and the accuracy of the test results.

[0086] Furthermore, in step two, if the control command sent by the control terminal (e.g., a computer or mobile phone) does not match the actual situation, the control unit 19 compares the calculation formula (1) with the specified threshold e, and controls the pressure self-control device to perform pressurization or depressurization operations. Preferably, if the pressurization or depressurization command sent by the control terminal (computer or mobile phone) is opposite to the actual situation, that is, when the target pressurization pressure value F is received... d ,but Then, perform the pressure relief operation using the above-described pressure relief steps; upon receiving the target pressure value F... d ,but Then, follow the pressurization steps described above to perform the pressurization operation.

[0087] The specific staged pressurization process is as follows: When the ratio B of the error between the real-time pressure value and the target pressure value to the target pressure value is less than 0, the control unit 19 controls the pressure self-control device to pressurize:

[0088] Open loading valve 13 and start DC motor 8;

[0089] Continuously acquire real-time pressure values ​​and determine the control phase based on the B value.

[0090] like Figure 6 As shown, when B ≤ -20%, the DC motor 8 is modulated to 100% speed, i.e., full speed rotation, and the real-time pressure value F is read at regular intervals. t Using the current real-time pressure value F t(n+1) Subtract the previous real-time pressure value F tn Obtain the rate of change of pressure For each calculation of a certain number of pressure change rates And calculate the first average pressure change value As the real-time pressure value F t is continuously read, continuously use the first average pressure change value to update the full-speed average pressure change value D 全 .

[0091] Specifically, read the real-time pressure value F every 10 milliseconds t and record them as F t1 , F t2 , F t3 ... F t(n+1) , use the current real-time pressure value minus the previous real-time pressure value to obtain the pressure change rate, and record them respectively as That is n is a natural number greater than or equal to 1, that is to say represents the pressure change rate every 10 milliseconds. Every time 10 pressure change rates are calculated, sort them from small to large, then remove the maximum value and the minimum value, add the remaining values, and divide the sum by 8 to get the first average pressure change value The first average pressure change value represents the average pressure change rate every 10 milliseconds when the DC motor 8 runs at full speed; as the real-time pressure value F t is continuously read, every time 10 new pressure change rates are calculated then update the first average pressure change value once and use to update the full-speed average pressure change value D 全 ;

[0092] As the pressurization continues, when -20% < B ≤ -10%, modulate the DC motor 8 to 50% speed, that is, half-speed rotation, use the current real-time pressure value minus the previous real-time pressure value to obtain the pressure change rate, and calculate the second average pressure change value when the DC motor 8 rotates at half speed and calculate the first average pressure change value according to the following calculation formula (2) and the second average pressure change value to update the full-speed average pressure change value D according to the result of the average value 全 ; as the real-time pressure value is continuously read is continuously updated, and D 全 is also continuously updated

[0093]

[0094] As the pressurization continues, when -10% < B < -|e|, the rotation speed of the DC motor 8 is set according to the following calculation formula (3)

[0095]

[0096] in:

[0097] V is the rotational speed of DC motor 8.

[0098] F d V is the target pressure value. 全 This is the speed value of DC motor 8 rotating at full speed.

[0099] ││ represents absolute value.

[0100] e represents the specified threshold.

[0101] As pressurization continues, if -|e|≤B≤|e|, then the DC motor 8 stops working, the loading valve 13 is closed, and the current real-time pressure value is maintained within this range for the time required to maintain the target pressure value.

[0102] As pressurization continues, if 10% > B > |e|, the unloading valve 12 is opened, and the DC motor 8 is started at the speed obtained by calculation formula (3) to unload pressure.

[0103] The specific staged pressure relief process is as follows: When the ratio B of the error between the real-time pressure value and the target pressure value to the target pressure value is greater than 0, it indicates that the real-time pressure value F t Greater than the target pressure value F d The control unit 19 controls the pressure self-control device to perform a pressure relief operation:

[0104] Open unloading valve 12 and start DC motor 8;

[0105] Continuously acquire real-time pressure values ​​and determine the control stage based on the B value.

[0106] like Figure 7 As shown, when B ≥ 20%, the DC motor 8 is modulated to full speed, and the real-time pressure value F is read at regular intervals. t Using the current real-time pressure value F t(n+1) Subtract the previous real-time pressure value F tn Obtain the rate of change of pressure n is a natural number ≥ 1; for each calculation of a certain number of pressure change rates The first average pressure change value was calculated. With real-time pressure value F t The data is continuously read and continuously used with the first average pressure change value. Update the full-speed average pressure change value D 全 ;

[0107] Specifically, the real-time stress value F is read every 10 milliseconds. t And denote them as F respectivelyt1 , F t2 , F t3 ……F t(n+1) , and subtract the previous real-time pressure value from the current real-time pressure value, and record them respectively as That is That is to say, represents the pressure change rate per 10 milliseconds. For every 10 pressure change rates calculated, sort them from small to large, then remove the maximum value and the minimum value, add the remaining values, and divide the sum by 8 to obtain the first average pressure change value The first average pressure change value represents the average pressure change rate per 10 milliseconds when the DC motor 8 runs at full speed; as the real-time pressure value F t is continuously read, for every newly calculated 10 pressure change rates then use the first average pressure change value to update the full-speed average pressure change value D once 全 ;

[0108] As the pressure relief continues, when 10% ≤ B < 20%, keep the unloading valve 12 open at this time, and modulate the DC motor 8 to rotate at half speed. Calculate the second average pressure change value when the DC motor 8 rotates at half speed in the same way as in step 1 and calculate the first average pressure change value according to the following calculation formula (2) and the second average pressure change value of the average value to update the full-speed average pressure change value D 全 ,

[0109]

[0110] As the pressure relief continues, at this time if |e| < B < 10%, the rotation speed of the DC motor 8 is set according to the calculation formula (3);

[0111]

[0112] Where:

[0113] V is the rotation speed of the DC motor 8,

[0114] F d is the target pressure value,

[0115] V 全 is the speed value when the DC motor 8 rotates at full speed,

[0116] ││ represents the absolute value,

[0117] e represents the specified threshold;

[0118] As the pressure relief continues, when -|e| ≤ B ≤ |e|, the operation of the DC motor 8 is stopped, the unloading valve 12 is closed, and the current real-time pressure value is maintained within this range according to the time required to maintain the target pressure value; during the maintenance process, if -10% < B < -|e|, the loading valve 13 is opened, and the DC motor 8 is started to pressurize at the rotational speed obtained by the calculation formula (3).

[0119] Under normal circumstances, the above steps of pressurization or pressure relief are continuous processes. However, during the actual test process, there may be various unknown reasons such as power failure that cause the device to stop working, and the hydraulic jack 5 still maintains the pressure at the moment before the power failure. When the device works normally again, the control stage where the pressure self-control device actually is is determined by calculating the B value, and the pressurization or pressure relief operation is continued according to this control stage, that is, the device continues to work according to the state before it stopped working.

[0120] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pressure self-control device for static load testing of foundation piles, comprising a control unit, a valve assembly, a drive unit, a power supply, a detection unit, an oil reservoir, an oil outlet pipe, an oil return pipe, and an execution unit, characterized in that, The valve assembly includes a loading valve and an unloading valve; the drive unit, the detection unit, the loading valve, and the unloading valve are all connected to the control unit; the output end of the drive unit is connected to the input end of the oil pump, and the drive unit drives the oil pump to rotate synchronously; the control unit controls the speed of the drive unit; one end of the oil pump inlet pipe is connected to an oil storage tank, and the other end of the inlet pipe can be selectively connected to the outlet pipe and the return pipe; the outlet pipe is connected to the inlet end of the execution unit, and an outlet pipe branch is connected to the outlet pipe, which is connected to the oil storage tank through an unloading valve; the return pipe is connected to the outlet end of the execution unit, and a return pipe branch is connected between the return pipe and the execution unit, which is connected to the oil storage tank through a loading valve; the detection unit is installed on the outlet pipe for real-time measurement of the oil pressure in the outlet pipe; the power supply provides electrical energy to the device; The control method for the pressure self-control device used in the static load test of the foundation pile includes the following steps: Step 1: Obtain the target pressure value Parameter information; the control unit reads the pressure value of the detection unit in real time and calculates the real-time pressure value of the execution unit based on the conversion factor of the execution unit. ; Step 2: Determine the pressurization or depressurization mode; Step 3: Based on the calculation results of formula (1), determine the control stage for pressurization or depressurization, and perform staged pressurization or staged depressurization operations. During the execution process, continuously obtain the real-time pressure value. (1); Real-time pressure value With target pressure value The ratio of the error between the values ​​to the target pressure value; Step 4: Maintain the target pressure value The required time to maintain Within the specified threshold e: If not within the specified threshold e, repeat step three; if within the specified threshold e, maintain... Within the specified threshold e; when When the loading valve is opened, the control unit controls the pressure self-control device to perform staged pressurization; when At that time, the unloading valve is opened, and the control unit controls the pressure to automatically unload the pressure in stages using the control device; The staged pressurization or staged depressurization operation is as follows: when or At that time, the drive unit is tuned to full speed rotation, and the real-time pressure value is read at regular intervals. Using the current real-time pressure value Subtract the previous real-time pressure value Obtain the rate of change of pressure n is a natural number ≥ 1; for each calculation of a certain number of pressure change rates And calculate the first average pressure change value. With real-time pressure values The data is continuously read and continuously used with the first average pressure change value. Update the full-speed average pressure change value ; when or At the same time, keep the corresponding valve open and adjust the drive unit to rotate at half speed. Calculate the second average pressure change value when the drive unit rotates at half speed, similar to the steps above. And calculate the first average pressure change value according to formula (2). Second average pressure change value The average value is used to update the full-speed average pressure change value. , （2）； when or At that time, the rotation speed of the drive unit is set according to the calculation formula (3). （3） in: The rotational speed of the drive unit, For the target pressure value, This represents the speed at which the drive unit rotates at full speed. ││ represents absolute value. e indicates the specified threshold; when If the pressure value is reached, the drive unit will stop operating, the loading and unloading valves will be closed, the drive unit will stop rotating, and the pressure value will be maintained. If, during the maintenance process... When the rotational speed is calculated using formula (3), the loading valve is opened to activate the drive unit and apply pressure; if the rotational speed is maintained during the process, When the pressure is released, the unloading valve is opened, and the drive unit is activated to release pressure at the rotational speed obtained by formula (3).

2. The pressure self-control device for static load testing of foundation piles according to claim 1, characterized in that, The oil pump is equipped with a three-way valve, which allows the oil inlet pipe to be selectively connected to the oil outlet pipe or the oil return pipe. The actuator is a hydraulic jack.

3. The pressure self-control device for static load testing of foundation piles according to claim 2, characterized in that, A first check valve is installed on the oil outlet pipe between the three-way valve and the hydraulic jack. The first check valve prevents hydraulic oil from flowing back into the oil pump outlet. A second check valve is installed on the oil return pipe between the three-way valve and the hydraulic jack. The second check valve prevents hydraulic oil from flowing back into the oil pump outlet.

4. The pressure self-control device for static load testing of foundation piles according to claim 2, characterized in that, The detection unit is set as an oil pressure sensor, the oil outlet pipe is connected to the branch of the oil outlet pipe through a tee connector, and the oil pressure sensor is installed on the tee connector.

5. The control method of the pressure self-control device for static load testing of foundation piles according to claim 1, characterized in that, The specific staged pressurization process is as follows: when At that time, the loading valve is opened, and the drive unit is tuned to full speed rotation. The real-time pressure value is read at regular intervals. Current real-time pressure value Subtract the previous real-time pressure value Obtain the rate of change of pressure Where n is a natural number ≥ 1, and the pressure change rate is calculated for a certain number of times. Then the first average pressure change value is calculated. With real-time pressure values The data is continuously read and continuously used with the first average pressure change value. Update the full-speed average pressure change value ; As the pressurization continues, when At this time, keep the loading valve open and modulate the drive unit to rotate at half speed. Calculate the second average pressure change value when the drive unit rotates at half speed, similar to the steps above. And calculate the first average pressure change value according to formula (2). Second average pressure change value The average value is used to update the full-speed average pressure change value. ; As the pressurization continues, when At that time, the rotation speed of the drive unit is set according to the calculation formula (3); As the pressurization continues, when If the pressure value is reached, the drive unit will stop operating, the loading valve will be closed, the drive unit will stop rotating, and the pressure value will be maintained. If, during the maintenance process... When the pressure is released, the unloading valve is opened, and the drive unit is activated to release pressure at the rotational speed obtained by formula (3).

6. The control method of the pressure self-control device for static load testing of foundation piles according to claim 1, characterized in that, The specific depressurization process is as follows: when At that time, the unloading valve is opened, and the drive unit is tuned to full speed rotation. The real-time pressure value is read at regular intervals. Using the current real-time pressure value Subtract the previous real-time pressure value Obtain the rate of change of pressure n is a natural number ≥ 1; for each calculation of a certain number of pressure change rates And calculate the first average pressure change value. With real-time pressure values The data is continuously read and continuously used with the first average pressure change value. Update the full-speed average pressure change value ; As depressurization continues, when At this time, keep the unloading valve open and adjust the drive unit to rotate at half speed. Calculate the second average pressure change value when the drive unit rotates at half speed, similar to the steps above. And calculate the first average pressure change value according to formula (2). Second average pressure change value The average value is used to update the full-speed average pressure change value. ; As depressurization continues, when At that time, the rotation speed of the drive unit is set according to the calculation formula (3); As the depressurization process continues, If the pressure value is reached, the drive unit will stop operating, the unloading valve will be closed, the drive unit will stop rotating, and the pressure value will be maintained at that time; if during the maintenance process, When the rotation speed is calculated using formula (3), the loading valve is opened to activate the drive unit for pressurization.

7. The control method of the pressure self-control device for static load testing of foundation piles according to claim 1, characterized in that, In step two, the control terminal sends a pressurization or depressurization command. If the command sent by the control terminal does not match the actual situation, the control unit compares the calculation formula (1) with the specified threshold e and controls the pressure self-control device to perform pressurization or depressurization operation.

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