Operation method and ground improvement device

Abstract

The challenge is to be able to indirectly detect negative pressure propagation even if it is not possible to directly observe its occurrence. When operating a ground improvement device comprising: a well buried in the ground, protruding above ground level, and taking in groundwater; a vacuum pump that creates a vacuum in the area inside the well above the surface of the groundwater; a water pump placed inside the well and pumping the groundwater inside the well up to the surface; and a flow control valve that controls the flow rate of the water pumped up by the water pumping pump by controlling the opening degree, the flow rate of the water pumped up by the water pumping pump is adjusted by the flow control valve while the vacuum pump and the water pumping pump are operating, so that abnormal noise is periodically generated from the water pumping pump.

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an operation method and a ground improvement device. [Background technology]

[0002] Patent Document 1 discloses a ground improvement method. In this improvement method, a well is placed in the ground, a strainer is installed at the bottom of the well, and groundwater enters the well through the strainer. A vacuum pump is connected to the well above ground. The vacuum pump sucks in air above the water level inside the well. A pump is placed at the bottom inside the well, and a pipe inside the well is piped from the pump to the surface. The pump sucks in the groundwater and air bubbles inside the well and pumps it up to the surface. Because the pumping capacity of the pump is greater than the amount of spring water entering the well, the water level inside the well drops to the pump's intake. This causes negative pressure to propagate from the inside to the outside of the well. However, the occurrence of this negative pressure propagation cannot be directly observed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-144871 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem that the technology disclosed in this specification aims to solve is to make it possible to indirectly detect the phenomenon of negative pressure propagation even if it is not possible to directly observe the occurrence of the negative pressure propagation. [Means for solving the problem]

[0005] In order to solve the above problems, when operating a ground improvement device comprising: a well buried in the ground, protruding above ground level, and taking in groundwater; a vacuum pump that evacuates an area above the surface of the groundwater inside the well; a water pump disposed inside the well and pumping the groundwater inside the well to the surface; and a flow control valve that controls the flow rate of the water pumped up by the water pump by controlling the opening degree, the flow rate of the water pumped up by the water pump is adjusted by the flow control valve while the vacuum pump and the water pump are operating, and abnormal noise is periodically generated from the water pump. A method of operation is provided.

[0006] In order to solve the above problems, there is provided a ground improvement device comprising: a well that is buried in the ground, protruding above ground level, and that takes in groundwater; a vacuum pump that creates a vacuum in the area inside the well above the surface of the groundwater; a pumping pump that is placed inside the well and pumps the groundwater inside the well up to the surface; a flow control valve that controls the flow rate of the water pumped up by the pumping pump by controlling its opening; an acoustic sensor that detects sounds inside the well; and a control unit that controls the flow control valve based on the output signal of the acoustic sensor.

[0007] In order to solve the above problems, a ground improvement device is provided that includes: a well that is buried in the ground, protruding above ground level, and that takes in groundwater; a vacuum pump that creates a vacuum in the area inside the well above the surface of the groundwater; a pumping pump that is placed inside the well and pumps the groundwater inside the well up to the surface; a flow control valve that controls the flow rate of the pumped water pumped up by the pumping pump by controlling its opening; a flow meter that measures the flow rate of the pumped water after passing through the flow control valve; and a control unit that controls the flow control valve based on the output signal of the flow meter.

[0008] In order to solve the above problems, a ground improvement device is provided that includes: a well that is buried in the ground, protruding above ground level, and that takes in groundwater; a vacuum pump that creates a vacuum in the area inside the well above the surface of the groundwater; a pumping pump that is placed inside the well and pumps the groundwater inside the well up to the surface; a flow control valve that controls the flow rate of the pumped water pumped up by the pumping pump by controlling its opening; an acoustic sensor that detects sounds inside the well; a flow meter that measures the flow rate of the pumped water after passing through the flow control valve; and a control unit that controls the flow control valve based on the output signals of the acoustic sensor and the flow meter.

[0009] The features, objects and advantages of the operating method and the soil improvement device will become apparent from the drawings showing preferred embodiments and the description thereof. [Effects of the Invention]

[0010] Even if the occurrence of negative pressure propagation cannot be directly observed, it can be indirectly detected by an acoustic sensor or a flow meter. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of the ground on which the soil improvement device is installed. [Figure 2] FIG. 2 is a timing chart of the signal output from the acoustic sensor when the ground improvement device is in a steady state of operation. [Figure 3] FIG. 3 is a timing chart of the signal output from the water level meter of the weir-type flow meter when the ground improvement device is in a steady operating state. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described with reference to the drawings. Features and technical effects of the embodiments will be understood from the following detailed description and drawings. The scope of the present invention is not limited to the embodiments disclosed below. Because the drawings are provided for illustrative purposes only, the scope of the present invention is not limited to the examples in the drawings.

[0013] 1. Ground improvement equipment FIG. 1 is a cross-sectional view of ground 99. A part of the ground improvement device 1 is installed in the ground 99 so as to be embedded in the ground 99, and another part of the ground improvement device 1 is installed above ground. This ground improvement device 1 pumps up pore water underground, such as saturated groundwater, thereby lowering the groundwater level and improving the soft ground 99 so that it hardens. The soil of the ground 99 may be clayey or sandy. Note that the soil around the ground 99 to be improved by the ground improvement device 1 may be held in place by sheet piles, retaining walls, continuous column walls, retaining walls, or earth retaining structures to prevent collapse. The ground 99 to be improved by the ground improvement device 1 may be an excavated depression. Water from the sea, lake, river, or the like may be blocked by a damming structure such as a caisson, sheet piles, retaining walls, or continuous column walls, exposing the bottom of the sea, lake, or river to the air, and this bottom may be improved by the ground improvement device 1 as the ground 99.

[0014] The ground improvement device 1 includes a well 10, a water pump 20, a water supply pipe 21, a flow control valve 30, a weir-type flow meter 40, a vacuum pump 50, a suction pipe 51, a vacuum pressure gauge 60, a control unit 70, and an acoustic sensor 80.

[0015] Well 10 is buried in ground 99. The top of well 10 protrudes above the ground surface. Well 10 draws groundwater from the ground into its interior. The lower part of the underground portion of well 10 allows the groundwater to seep into the well 10, while the upper part of the underground portion shields the groundwater from the ground. Well 10 has an inner pipe 11, a strainer pipe 12, a cap 13, and a sediment collection pipe 15.

[0016] The inner pipe 11 is made of a steel pipe. The inner pipe 11 is buried in the ground 99 with its central axis vertical. The upper part of the inner pipe 11 protrudes upward from the ground surface. The inner pipe 11 has multiple holes 14 at the lower end of its outer periphery. These holes 14 penetrate from the outer periphery to the inner periphery of the inner pipe 11, and water passes through the holes 14.

[0017] The lower part of the inner pipe 11 is inserted into the strainer pipe 12. The strainer pipe 12 is spaced radially outward from the inner pipe 11, and a gap exists between the inner pipe 11 and the strainer pipe 12. The upper end of the gap is closed and the lower end of the gap is closed. Holes 14 formed in the inner pipe 11 are on the inside of the strainer pipe 12. The holes 14 are positioned near the lower end of the strainer pipe 12. The strainer pipe 12 filters groundwater and captures sediment. The groundwater filtered by the strainer pipe 12 permeates the inside of the strainer pipe 12. Inside the strainer pipe 12, water flows toward the holes 14, and the water flows through the holes 14 into the inside of the inner pipe 11.

[0018] The strainer tube 12 may be made of a spirally wound wire. The strainer tube 12 may be made of a plurality of rings stacked at regular short intervals along the central axis. The strainer tube 12 may be made of a punched steel pipe in which a plurality of small holes are formed. The strainer tube 12 may be made of a slitted steel pipe in which a plurality of longitudinal or circumferential slits are formed in the steel pipe.

[0019] The sediment collection pipe 15 is connected to the lower end of the inner pipe 11. The lower end of the sediment collection pipe 15 may be closed by a lid or the like. Sediment that has not been completely separated from the groundwater by the strainer pipe 12 is collected in the sediment collection pipe 15.

[0020] The cap 13 is attached to the upper end of the inner tube 11. The upper end of the inner tube 11 is closed by the cap 13.

[0021] Water inside the well 10, i.e., inside the inner pipe 11, is pumped to the weir-type flow meter 40 by the pumping pump 20. The pumping pump 20 is arranged inside the inner pipe 11 and above the hole 14. In particular, the suction port of the pumping pump 20 is arranged above the hole 14. The pumping pump 20 is, for example, a centrifugal pump. The type of the pumping pump 20 may be a turbo pump other than a centrifugal pump. The pumping pump 20 may be controlled by the control unit 70.

[0022] The pumping capacity of the pump 20, i.e., the maximum discharge volume of the pump 20 (m 3 / min) is the amount of water (m 3 / min).

[0023] The water pump 20 is connected to the lower end of the water supply pipe 21 inside the inner pipe 11. The water supply pipe 21 is provided inside the inner pipe 11 with its central axis vertical. The water supply pipe 21 and the inner pipe 11 may be arranged coaxially. The water supply pipe 21 passes through the cap 13 from top to bottom. The water supply pipe 21 is installed on the ground from the cap 13 to a weir-type flow meter 40. The flow rate of water sent by the water supply pipe 21 is controlled by a flow control valve 30, and the water flow rate is measured by the weir-type flow meter 40. The weir-type flow meter 40 outputs a signal indicating the measured value of the water flow rate to the control unit 70.

[0024] The flow control valve 30 is provided on the ground in the middle of the water pipe 21 from the cap 13 to the weir-type flow meter 40. The flow control valve 30 is an electrically operated valve such as a solenoid valve that controls the flow rate of water by operating under electrical control. The flow control valve 30 may be controlled by the control unit 70.

[0025] The weir type flow meter 40 has a temporary water storage tank 41 , a weir 44 and a water level gauge 45 .

[0026] The temporary water storage tank 41 is installed on the ground near the well 10. The temporary water storage tank 41 is cubic or rectangular, and its top end is open. The inside of the temporary water storage tank 41 is divided into a primary storage section 42 and a secondary storage section 43 by a weir 44, such as a triangular weir, a rectangular weir, or a full-width weir. The weir 44 stands perpendicular and plumb to the bottom of the temporary water storage tank 41. The weir 44 is perpendicular to the side of the temporary water storage tank 41 and parallel to the front and rear surfaces of the temporary water storage tank 41. If the weir 44 is a triangular weir, the weir 44 has a triangular notch at its top end. If the weir 44 is a rectangular weir, the weir 44 has a rectangular notch at its top end. If the weir 44 is a full width weir, the weir 44 does not have a notch at its top end.

[0027] A water pipe 21 is installed above ground from the cap 13 to the primary storage section 42, and water pumped up by a water pump 20 flows from the end of the water pipe 21 into the primary storage section 42. The water that flows into the primary storage section 42 is stored there, and then overflows from the primary storage section 42 into the secondary storage section 43 over a weir 44. The water level inside the primary storage section 42 rises and falls depending on the flow rate of the overflow water, i.e., the flow rate of the water flowing into the primary storage section 42. In other words, as the flow rate of water flowing into the primary storage section 42 increases, the water level inside the primary storage section 42 rises, and as the flow rate of water flowing into the primary storage section 42 decreases, the water level inside the primary storage section 42 rises and falls. The water inside the secondary storage section 43 is discharged through a drain pipe or the like. The primary storage section 42 may be provided with a flow rectifying section that rectifies the water heading toward the weir 44 .

[0028] An open channel may be used instead of the temporary water storage tank 41. In that case, a weir 44 may be provided in the open channel, and the water in the open channel may be blocked by the weir 44 and may overflow the weir 44.

[0029] The water level meter 45 measures the water level inside the primary storage section 42 and outputs a signal representing the measured water level to the control section 70. Because the flow rate of water flowing into the primary storage section 42 can be converted from the water level inside the primary storage section 42, the output signal of the water level meter 45 also represents the flow rate of water flowing into the primary storage section 42. In other words, the output signal of the water level meter 45 corresponds to the output signal of the weir type flow meter 40. The output signal of the water level meter 45 may be either a digital or analog signal. The water level meter 45 may have a display or pointer, and the measured value of the flow rate may be displayed by the display or pointer.

[0030] The water level gauge 45 may be of a contact type or a non-contact type. A contact type water level gauge 45 measures the water level by directly contacting the water inside the primary storage section 42. The contact type water level gauge 45 may be, for example, a pressure type, guide pulse type, capacitance type, float type, or differential pressure type water level gauge. A non-contact type water level gauge may be a radio wave type or ultrasonic type water level gauge that measures the distance from the non-contact type water level gauge to the water surface in the primary storage section 42. The distance to the water surface in the primary storage section 42 can be converted into the water level, and ultimately into the flow rate.

[0031] The inside of the well 10, i.e., the area above the water surface inside the inner pipe 11, is evacuated by a vacuum pump 50. The vacuum pump 50 is installed on the ground near the well 10. A suction pipe 51 is piped from the vacuum pump 50 to the inner pipe 11. Specifically, a first end of the suction pipe 51 is connected to the vacuum pump 50, and a second end of the suction pipe 51 is connected to the cap 13 on the ground. The vacuum pump 50 sucks air from the area above the water surface in the well 10 through the suction pipe 51 and releases the air into the atmosphere. The vacuum pump 50 may be controlled by a control unit 70.

[0032] The degree of vacuum inside the inner tube 11 is measured by a vacuum pressure gauge 60. The vacuum pressure gauge 60 is provided in the cap 13. The vacuum pressure gauge 60 may also be provided in the inner tube 11. The vacuum pressure gauge 60 outputs a signal representing the measured value of the degree of vacuum to the control unit 70. The output signal of the vacuum pressure gauge 60 may be either a digital or analog signal. The vacuum pressure gauge 60 may have a display or pointer, and the measured value of the degree of vacuum may be displayed by the display or pointer. The control unit 70 may monitor the output signal of the vacuum pressure gauge 60.

[0033] When the vacuum pump 50 and the water lifting pump 20 are operating steadily, the hollow region above the water surface inside the inner pipe 11 is evacuated to an appropriate vacuum level by the vacuum pump 50, and the water lifting pump 20 is driven at an appropriate speed. For example, when the vacuum pump 50 and the water lifting pump 20 are operating steadily, the hollow region inside the inner pipe 11 is evacuated to a vacuum level close to the maximum capacity of the vacuum pump 50, and the water lifting pump 20 is driven at an appropriate speed close to its maximum capacity.

[0034] When the vacuum pump 50 and the pumping pump 20 are operating normally, the flow rate of water pumped by the pumping pump 20 is appropriately controlled by the flow control valve 30. Here, an increase in the flow rate of the pumped water contributes to lowering the water level inside the inner pipe 11. On the other hand, the vacuum in the hollow region inside the inner pipe 11 contributes to raising the water level inside the inner pipe 11. Therefore, the vacuum in the region above the water level inside the inner pipe 11 contributes to the flow rate of the pumped water being controlled to as large an appropriate value as possible by the flow control valve 30. By controlling the flow rate of the pumped water to as large an appropriate value as possible by the flow control valve 30 during normal operation of the vacuum pump 50 and the pumping pump 20, the water level inside the inner pipe 11 is lowered to and maintained at the level of the pumping pump 20.

[0035] Because the inside of the inner pipe 11 is evacuated, negative pressure is generated in the water inside the inner pipe 11. The negative pressure also propagates to the groundwater outside the strainer pipe 12, contributing to the sucking of the groundwater outside the strainer pipe 12 into the inside of the strainer pipe 12. This significantly lowers the groundwater level outside the strainer pipe 12, creating a large unsaturated zone above the groundwater. This negative pressure causes cavitation in the groundwater outside the strainer pipe 12. This is because the groundwater vaporizes due to a drop in water pressure, generating bubbles in the groundwater. The bubbles are drawn into the strainer pipe 12 along with the groundwater. Small bubbles gather together, forming larger bubbles in the groundwater. When these larger bubbles reach the pumping pump 20, they are drawn into the pumping pump 20. This causes abnormal noise in the pumping pump 20 and a decrease in the pumping flow rate. Since large bubbles are generated periodically, abnormal noise and a decrease in the pumping flow rate occur periodically.

[0036] However, if the flow control valve 30 is opened excessively, causing the pumping flow rate to be higher than the appropriate value, the water level inside the inner pipe 11 will drop excessively. This will cause the suction hole of the pumping pump 20 to be above the water level inside the inner pipe 11. This will cause the pumping pump 20 to make continuous abnormal noises. The air from above ground will enter the inside of the inner pipe 11 through the water supply pipe 21 and the pumping pump 20, causing a decrease in the degree of vacuum inside the inner pipe 11. The decrease in the degree of vacuum inside the inner pipe 11 will lead to a decrease in the negative pressure of the groundwater, making it difficult for cavitation to occur in the groundwater. On the other hand, if the flow control valve 30 is opened too little and the pumped water flow rate is lower than the appropriate value, the water level inside the inner pipe 11 will rise excessively. As a result, even if negative pressure is generated in the water inside the inner pipe 11, the negative pressure is unlikely to propagate to the groundwater outside the strainer pipe 12. As a result, cavitation is unlikely to occur in the groundwater.

[0037] Therefore, by appropriately controlling the pumping flow rate using the flow control valve 30, cavitation occurs appropriately in the groundwater. This causes the periodic formation of large bubbles, the periodic occurrence of abnormal noise in the pumping pump 20, and a periodic decrease in the pumping flow rate. However, the appropriate value of the pumping flow rate is affected by various factors. For example, the appropriate value of the pumping flow rate is affected by the soil quality of the ground 99, the groundwater pressure, the viscosity of the groundwater, the maximum capacity of the pumping pump 20, the maximum capacity of the vacuum pump 50, the diameter of the inner pipe 11, the diameter of the strainer pipe 12, and the amount of water passing through the strainer pipe 12. Therefore, the appropriate value of the pumping flow rate cannot be determined in general. Therefore, the ground improvement device 1 detects, records, or manages the periodic occurrence of abnormal noise and the periodic decrease in the pumping flow rate, and appropriately controls the pumping flow rate using the flow control valve 30 using the results of this detection, recording, or management. This will be described in detail below.

[0038] The acoustic sensor 80 is prepared for detecting, recording, or managing the periodic occurrence of abnormal sounds. The acoustic sensor 80 is used to observe sounds inside the well 10, particularly the inner pipe 11. The acoustic sensor 80 is, for example, a microphone, a piezoelectric element, a strain gauge, a displacement sensor, a velocity sensor, an acceleration sensor, or a vibration sensor. The acoustic sensor 80 is attached to the well 10, particularly to a portion of the well 10 that protrudes above ground. For example, the acoustic sensor 80 is attached to the inner pipe 11 or the cap 13. The acoustic sensor 80 may be attached to the outer or inner surface of the inner pipe 11 or the cap 13. The acoustic sensor 80 may also be located on the inner pipe 11. The acoustic sensor 80 detects sounds, i.e., vibrations, inside the well 10, particularly the inner pipe 11, and converts the vibrations into an electrical signal. The acoustic sensor 80 or the control unit 70 has an AD converter, and the acoustic sensor 80 outputs a digital or analog electrical signal to the control unit 70. The sound generated by the water pump 20, that is, the abnormal sound generated when large air bubbles are taken into the water pump 20, is superimposed on the electrical signal output by the acoustic sensor 80 as a signal.

[0039] 2 is a time chart of the output signal of the acoustic sensor 80. When the flow rate of the pumped water is appropriately controlled by the flow control valve 30 during steady operation of the vacuum pump 50 and the water pumping pump 20, abnormal noise occurs in the water pumping pump 20, and the amplitude of the output signal of the acoustic sensor 80 periodically increases in synchronization with the occurrence of the abnormal noise.

[0040] The acoustic sensor 80 may have an oscilloscope, and the change in the output signal of the acoustic sensor 80 may be displayed by the oscilloscope.

[0041] The weir type flow meter 40 is prepared for detecting, recording, or managing the periodic occurrence of abnormal noise, and more directly for detecting, recording, or managing the periodic occurrence of the flow rate of pumped water. The weir type flow meter 40 is used to observe the flow rate of pumped water that has passed through the flow control valve 30. As described above, the weir type flow meter 40 outputs a signal representing the measured value of the water flow rate to the control unit 70. In other words, the water level indicator 45 outputs a signal representing the measured value of the water level inside the primary storage unit 42 to the control unit 70.

[0042] Figure 3 is a time chart of the output signal of the weir-type flow meter 40, i.e., the water level meter 45. If the flow rate of the pumped water is appropriately controlled by the flow control valve 30 during steady operation of the vacuum pump 50 and the pumping pump 20, the flow rate of the pumped water will periodically decrease, and the level of the output signal of the water level meter 45 will periodically change to synchronize with the decrease in the flow rate of the pumped water. In the example shown in Figure 3, the periodic changes in the output signal of the water level meter 45 are falling edges. If the output signal of the water level meter 45 is inverted by an inversion circuit or the like, the periodic changes in the output signal of the water level meter 45 are rising edges.

[0043] Output signals from the acoustic sensor 80 and the water level gauge 45 are input to the control unit 70. The control unit 70 has a main board, one or more central processing units (CPUs), one or more GPUs, random access memory (RAM), a storage device such as a solid state drive (SSD) or hard disk drive (HDD), and an input device. The main board has a bus, a bus controller, an interface circuit, etc. The main board transmits information between the CPU, GPU, RAM, storage device, and interface circuit.

[0044] The control unit 70 may have a digital or analog first filter that removes unnecessary components from the output signal of the acoustic sensor 80. The first filter may be a low-pass filter (high-cut filter), a high-pass filter (low-cut filter), a band-pass filter, or a band-cut filter. The cutoff frequency of the first filter may be variable.

[0045] The control unit 70 may have a digital or analog second filter that removes unnecessary components from the output signal of the water level gauge 45. The second filter may be a low-pass filter (high-cut filter), a high-pass filter (low-cut filter), a band-pass filter, or a band-cut filter. The cutoff frequency of the second filter may be variable.

[0046] The control unit 70 records the output signal values ​​of the acoustic sensor 80 in a time series at very short intervals in the storage device. As a result, the control unit 70 generates time-series acoustic data in the storage device, which is obtained by arranging the output signal values ​​of the acoustic sensor 80 in time series.

[0047] The control unit 70 monitors the output signal of the acoustic sensor 80. As a result, the control unit 70 determines whether or not an abnormal sound is occurring periodically based on the output signal of the acoustic sensor 80. For example, if the amplitude of the output signal of the acoustic sensor 80 exceeds a threshold, the control unit 70 detects the occurrence of an abnormal sound, which triggers the control unit 70 to start timing. If the amplitude of the output signal of the acoustic sensor 80 subsequently falls below the threshold, and then the amplitude of the output signal of the acoustic sensor 80 exceeds the threshold, the control unit 70 detects the occurrence of an abnormal sound. Then, the control unit 70 determines whether or not an abnormal sound is occurring periodically based on the measured time, i.e., the occurrence cycle of the abnormal sound. The control unit 70 repeatedly performs this process.

[0048] The control unit 70 may determine whether or not abnormal noises occur periodically by analyzing the output signal of the acoustic sensor 80 through frequency analysis using a Fourier transform, specifically a fast Fourier transform. Alternatively, the control unit 70 may determine whether or not abnormal noises occur periodically using a trained model as software-based artificial intelligence (AI). For example, the control unit 70 may build, in RAM, a trained model composed of an artificial neural network having numerous parameters, such as weights or biases, calculated through deep learning processing. The control unit 70 inputs time-series data from the output signal of the acoustic sensor 80 into the trained model. The control unit 70 then outputs a determination result indicating whether or not abnormal noises occur periodically from the trained model.

[0049] The control unit 70 records the output signal values ​​of the water level meter 45 in a time series at very short intervals in the storage device. As a result, the control unit 70 generates time-series flow rate data in the storage device, which is obtained by arranging the output signal values ​​of the water level meter 45 in time series.

[0050] The control unit 70 monitors the output signal from the water level meter 45. This allows the control unit 70 to determine whether or not there is a periodic decrease in the pumping flow rate based on the output signal from the water level meter 45. For example, if the value of the output signal from the water level meter 45 exceeds a threshold, the control unit 70 detects a decrease in the pumping flow rate, which triggers the control unit 70 to start measuring time. If the value of the output signal from the water level meter 45 subsequently falls below the threshold and then exceeds the threshold, the control unit 70 detects a decrease in the pumping flow rate and determines whether or not there is a periodic decrease in the pumping flow rate based on the measured time, i.e., the frequency with which the decrease in the pumping flow rate occurs. The control unit 70 repeatedly performs this process.

[0051] The control unit 70 may use a trained model constructed as software to determine whether or not there is a periodic decrease in the pumped water flow rate. That is, the control unit 70 inputs time-series data from the output signal of the water level meter 45 into the trained model. The control unit 70 then outputs a determination result indicating whether or not there is a periodic decrease in the pumped water flow rate from the trained model.

[0052] Each time it determines whether or not abnormal noise occurs periodically, or whether or not there is a periodic decrease in the pumped water flow rate, or each time it determines both of these, the control unit 70 controls the flow control valve 30 based on the determination results. When the control of the flow control valve 30 is based on both the determination of whether or not there is a periodic occurrence of abnormal noise and the determination of whether or not there is a periodic decrease in the pumped water flow rate, either the logical product or logical sum of the determination results of whether or not there is a periodic occurrence of abnormal noise and the determination results of whether or not there is a periodic decrease in the pumped water flow rate may be used. Several examples of the flow control valve 30 will be described.

[0053] Example 1: Result of determining whether abnormal noise occurs periodically If the control unit 70 determines, based on the output signal of the acoustic sensor 80, that abnormal noise is occurring periodically, the control unit 70 controls the flow control valve 30 to maintain the opening of the flow control valve 30. This controls the flow rate of the pumped water to an appropriate value. On the other hand, if the control unit 70 determines, based on the output signal of the acoustic sensor 80, that abnormal noise is not occurring periodically, the control unit 70 changes the opening of the flow control valve 30 by a predetermined amount, that is, controls the flow control valve 30 to increase or decrease the opening by a predetermined amount.

[0054] Example 2: Determination result of periodic decrease in pumped water flow rate If the control unit 70 determines, based on the output signal of the water level meter 45, that the pumping flow rate is being periodically reduced, the control unit 70 controls the flow control valve 30 to maintain the opening of the flow control valve 30. This controls the pumping flow rate to an appropriate value. On the other hand, if the control unit 70 determines, based on the output signal of the water level meter 45, that the pumping flow rate is not being periodically reduced, the control unit 70 controls the flow control valve 30 to change the opening of the flow control valve 30 by a predetermined amount, that is, to increase or decrease the opening by a predetermined amount. This causes the pumping flow rate to fluctuate toward an appropriate value.

[0055] Example 3: Logical OR of the results of determining whether abnormal noise occurs periodically and the results of determining whether the pumped water flow rate decreases periodically When the control unit 70 makes at least one of a positive determination that abnormal noises are occurring periodically based on the output signal of the acoustic sensor 80 and a positive determination that the pumping flow rate is periodically decreasing based on the output signal of the water level gauge 45, the control unit 70 controls the flow control valve 30 to maintain its opening degree. This controls the pumping flow rate to an appropriate value. On the other hand, when the control unit 70 makes both a negative determination that abnormal noises are occurring periodically based on the output signal of the acoustic sensor 80 and a negative determination that the pumping flow rate is periodically decreasing based on the output signal of the water level gauge 45, the control unit 70 changes the opening degree of the flow control valve 30 by a predetermined amount, i.e., controls the flow control valve 30 to increase or decrease the opening degree by a predetermined amount. This causes the pumping flow rate to fluctuate toward an appropriate value.

[0056] Example 4: Logical product of the results of determining whether abnormal noise occurs periodically and the results of determining whether the pumped water flow rate decreases periodically If the control unit 70 makes both a positive determination that abnormal noises are occurring periodically based on the output signal of the acoustic sensor 80 and a positive determination that the pumping water flow rate is periodically decreasing based on the output signal of the water level gauge 45, the control unit 70 controls the flow control valve 30 to maintain its opening degree. This controls the pumping water flow rate to an appropriate value. On the other hand, if the control unit 70 makes at least one of a negative determination that abnormal noises are occurring periodically based on the output signal of the acoustic sensor 80 and a negative determination that the pumping water flow rate is periodically decreasing based on the output signal of the water level gauge 45, the control unit 70 changes the opening degree of the flow control valve 30 by a predetermined amount, i.e., controls the flow control valve 30 to increase or decrease the opening degree by a predetermined amount. This causes the pumping water flow rate to fluctuate toward an appropriate value.

[0057] 2. How to operate the ground improvement equipment The following describes how to operate and use the ground improvement device 1 after installation of the ground improvement device 1. Additionally, the flow of processing by the control unit 70 while the ground improvement device 1 is in use will be described.

[0058] An operator turns on the power to the water pump 20, the flow control valve 30, the vacuum pump 50, and the control unit 70. An operator turns on the power to the water level gauge 45, the vacuum pressure gauge 60, and the acoustic sensor 80.

[0059] Next, an operator starts the lift pump 20. For example, the operator operates the control unit 70, and the control unit 70 controls the lift pump 20 to start the lift pump 20 in accordance with the operation. After the lift pump 20 starts, the control unit 70 may control the speed of the lift pump 20 for steady operation of the lift pump 20. For example, the control unit 70 may control the lift pump 20 at or near the maximum output of the lift pump 20.

[0060] Furthermore, the worker starts the flow control valve 30. For example, the worker operates the control unit 70, and the control unit 70 controls the flow control valve 30 to start the flow control valve 30 according to the operation. Then, the opening degree of the flow control valve 30 becomes a predetermined default value.

[0061] While the water pump 20 is operating, the control unit 70 monitors the output signal of the water level gauge 45 and the output signal of the acoustic sensor 80. The control unit 70 records the values ​​of the output signal of the water level gauge 45 in a time series in the storage device. The control unit 70 records the values ​​of the output signal of the acoustic sensor 80 in a time series in the storage device.

[0062] By controlling the water pumping pump 20, the water inside the inner pipe 11 is pumped up to the weir-type flow meter 40. The flow rate of the pumped water is adjusted according to the opening of the flow control valve 30. The water pumped by the water pumping pump 20 contributes to lowering the water level inside the inner pipe 11.

[0063] Before or after starting the water lifting pump 20, an operator starts the vacuum pump 50. For example, the operator operates the control unit 70, and the control unit 70 controls the vacuum pump 50 to start the vacuum pump 50 in accordance with the operation. After starting the vacuum pump 50, the control unit 70 may control the output of the vacuum pump 50. For example, the control unit 70 may control the vacuum pump 50 at or near the maximum output of the vacuum pump 50.

[0064] By controlling the vacuum pump 50, the air in the inner pipe 11 is sucked into the vacuum pump 50, and the pressure inside the inner pipe 11 decreases. The decrease in pressure inside the inner pipe 11 contributes to an increase in the water level inside the inner pipe 11.

[0065] During operation of the vacuum pump 50, the control unit 70 may monitor the output signal of the vacuum pressure gauge 60. The control unit 70 may record the values ​​of the output signal of the vacuum pressure gauge 60 in a storage device so as to arrange them in chronological order.

[0066] When the degree of vacuum measured by the vacuum pressure gauge 60 reaches a predetermined value, specifically, a degree of vacuum close to the maximum capacity of the vacuum pump 50, the operation of the vacuum pump 50 becomes steady, and the control unit 70 starts controlling the flow control valve 30 based on the output signal of the water level gauge 45, the output signal of the acoustic sensor 80, or both. For example, when an operator confirms that the degree of vacuum indicated by the display or pointer of the vacuum pressure gauge 60 is equal to a predetermined value, the operator may operate the control unit 70, which causes the control unit 70 to start controlling the flow control valve 30 based on the output signal of the water level gauge 45, the output signal of the acoustic sensor 80, or both. For example, when the control unit 70 determines that the value of the output signal of the vacuum pressure gauge 60 is equal to or greater than a predetermined value, the control unit 70 may start controlling the flow control valve 30 based on the output signal of the water level gauge 45, the output signal of the acoustic sensor 80, or both.

[0067] The control unit 70 then determines whether or not the pumped water flow rate is periodically decreasing based on the output signal of the water level meter 45. Furthermore, the control unit 70 determines whether or not abnormal noise is periodically occurring based on the output signal of the acoustic sensor 80.

[0068] At this point, the opening of the flow control valve 30, i.e., the flow rate of the pumped water, is usually not at an appropriate value. Therefore, the control unit 70 determines that the flow rate of the pumped water is not periodically decreasing based on the output signal of the water level gauge 45, and also determines that abnormal noise is not periodically occurring based on the output signal of the acoustic sensor 80. Then, as in any of Examples 1 to 4 above, the control unit 70 controls the flow control valve 30 to change the opening of the flow control valve 30 by a predetermined amount, i.e., to increase or decrease the opening by a predetermined amount.

[0069] Thereafter, the control unit 70 repeatedly changes the opening of the flow control valve 30 by a predetermined amount until the control unit 70 makes a positive determination that the pumped water flow rate is periodically decreasing, or until the control unit 70 makes a positive determination that abnormal noise is periodically occurring, or until the control unit 70 makes a positive determination of both. By repeatedly changing the opening of the flow control valve 30 by a predetermined amount, the pumped water flow rate gradually changes. The gradual change in the pumped water flow rate may be a gradual increase or a gradual decrease. The gradual change in the pumped water flow rate may be a gradual increase followed by a gradual decrease. The gradual change in the pumped water flow rate may be a gradual decrease followed by a gradual increase.

[0070] If the control unit 70 makes a positive determination that the flow rate of pumped water is periodically decreasing, or if the control unit 70 makes a positive determination that abnormal noise is periodically occurring, the control unit 70 controls the flow rate control valve 30 to maintain the opening of the flow rate control valve 30, as described in any of the above Examples 1 to 4. This controls the flow rate of pumped water to an appropriate value, and the ground improvement device 1 enters a steady operating state.

[0071] In addition, a worker on the surface may determine whether or not the pumping flow rate is periodically decreasing by observing the pumping flow rate on the display or pointer of the water level gauge 45. Furthermore, a worker may determine whether or not abnormal noises are periodically occurring by audibly observing the sounds inside the well 10. The worker manually operates the flow control valve 30 to gradually adjust the pumping flow rate until the worker confirms a periodic decrease in the pumping flow rate, the periodic occurrence of abnormal noises, or both. Once the worker confirms a periodic decrease in the pumping flow rate, the periodic occurrence of abnormal noises, or both, the worker stops adjusting the flow control valve 30, thereby stabilizing the pumping flow rate, and the ground improvement device 1 enters a steady operating state.

[0072] Even after the ground improvement device 1 has entered a steady operating state, the control unit 70 continues to monitor and record the output signals of the water level meter 45 and the acoustic sensor 80. After the ground improvement device 1 has entered a steady operating state, the opening of the flow control valve 30, i.e., the flow rate of the pumped water, is usually at an appropriate value. Therefore, the control unit 70 makes a positive determination of the periodic decrease in the flow rate of the pumped water based on the output signal of the water level meter 45, and also makes a positive determination of the periodic occurrence of abnormal noise based on the output signal of the acoustic sensor 80. However, for some reason, such as an excessive decrease or increase in groundwater, the periodic occurrence of abnormal noise and the periodic decrease in the flow rate of the pumped water may not occur.

[0073] In such a case, the control unit 70 determines that the pumped water flow rate has not decreased periodically based on the output signal of the water level meter 45, and also determines that abnormal noise has not occurred periodically based on the output signal of the acoustic sensor 80. Then, as in any of Examples 1 to 4 above, the control unit 70 controls the flow control valve 30 to change the opening of the flow control valve 30 by a predetermined amount. Thereafter, the control unit 70 repeats changing the opening of the flow control valve 30 by a predetermined amount until the control unit 70 determines that the pumped water flow rate has decreased periodically, or until the control unit 70 determines that abnormal noise has occurred periodically, or until the control unit 70 determines that both of these conditions have been met.

[0074] 3. Summary As described above, if the negative pressure generated by the vacuum pump 50 propagates outside the well 10, cavitation occurs in the groundwater, causing large bubbles to periodically form. When these large bubbles are drawn into the pumping pump 20, the pumping pump 20 generates abnormal noise and the pumping flow rate decreases. The acoustic sensor 80 detects sounds from inside the well 10, and the output signal from the acoustic sensor 80 can be used to determine whether the pumping pump 20 is periodically emitting abnormal noise. The acoustic sensor 80 can be used to detect the propagation of negative pressure to the groundwater by detecting the regular occurrence of abnormal noise. The pumping flow rate is detected by the water level gauge 45 of the weir-type flow meter 40, and the output signal from the water level gauge 45 can be used to determine whether the pumping flow rate periodically decreases. The water level gauge 45 of the weir-type flow meter 40 can be used to detect the propagation of negative pressure to the groundwater by detecting the regular decrease in the pumping flow rate.

[0075] This soil improvement device 1 is operated so as to reliably transmit negative pressure to the groundwater and to reliably generate cavitation in the groundwater. The transmission of negative pressure and the generation of cavitation contribute to maximizing the flow rate of water pumped by the water pumping pump 20, and ultimately to significantly lowering the groundwater level. [Explanation of symbols]

[0076] 1 Ground improvement equipment 10. Well 20 Water pump 30 Flow Control Valve 40 Weir type flowmeter 50 Vacuum Pump 80 Acoustic Sensor

Claims

1. A well is buried in the ground, protruding above ground, and draws groundwater. a vacuum pump for applying a vacuum to an area inside the well above the surface of the groundwater; a pump disposed inside the well and pumping the groundwater inside the well to the surface; a flow control valve that controls the flow rate of the water pumped by the water pumping pump by controlling the opening degree; When operating the ground improvement device, the flow rate of the pumped water is adjusted by the flow control valve while the vacuum pump and the pumping pump are in operation, so that abnormal noise is periodically generated from the pumping pump. How it works.

2. By observing the sounds inside the well, it is determined whether the abnormal sounds occur periodically. The method of claim 1 .

3. An acoustic sensor installed in the well observes the sounds inside the well. The operating method of claim 2.

4. The flow control valve adjusts the flow rate of the pumped water by adjusting the opening degree, By observing the flow rate of the pumped water that passes through the flow control valve, it is determined whether the abnormal noise occurs periodically.

3. The operating method according to claim 1 or 2.

5. The flow rate of the pumped water is observed using a flow meter installed downstream of the flow control valve. The operating method according to claim 4.

6. A well is buried in the ground, protruding above ground, and draws groundwater. a vacuum pump for applying a vacuum to an area inside the well above the surface of the groundwater; a pump disposed inside the well and pumping the groundwater inside the well to the surface; a flow control valve that controls the flow rate of the water pumped by the water pumping pump by controlling the opening degree; an acoustic sensor that detects sounds inside the well; a control unit that controls the flow control valve based on an output signal of the acoustic sensor; A ground improvement device equipped with:

7. The control unit a first process for determining whether or not an abnormal sound occurs periodically based on an output signal of the acoustic sensor; a second process of controlling the flow control valve so as to maintain the opening degree of the flow control valve when the determination of the first process is affirmative; a third process of controlling the flow control valve to change the opening degree of the flow control valve when the determination in the first process is negative; Run The ground improvement device according to claim 6.

8. A well is buried in the ground, protruding above ground, and draws groundwater. a vacuum pump for applying a vacuum to an area inside the well above the surface of the groundwater; a pump disposed inside the well and pumping the groundwater inside the well to the surface; a flow control valve that controls the flow rate of the water pumped by the water pumping pump by controlling the opening degree; a flow meter that measures the flow rate of the pumped water after passing through the flow control valve; a control unit that controls the flow control valve based on an output signal of the flow meter; A ground improvement device equipped with:

9. The control unit a first process for determining whether or not the pumped water flow rate is periodically reduced based on an output signal of the flow meter; a second process of controlling the flow control valve so as to maintain the opening degree of the flow control valve when the determination of the first process is affirmative; a third process of controlling the flow control valve to change the opening degree of the flow control valve when the determination in the first process is negative; Run The ground improvement device according to claim 8.

10. A well is buried in the ground, protruding above ground, and draws groundwater. a vacuum pump for applying a vacuum to an area inside the well above the surface of the groundwater; a pump disposed inside the well and pumping the groundwater inside the well to the surface; a flow control valve that controls the flow rate of the water pumped by the water pumping pump by controlling the opening degree; an acoustic sensor that detects sounds inside the well; a flow meter that measures the flow rate of the pumped water after passing through the flow control valve; a control unit that controls the flow control valve based on output signals from the acoustic sensor and the flow meter; A ground improvement device equipped with:

11. The control unit a first process for determining whether or not an abnormal sound occurs periodically based on an output signal of the acoustic sensor; a second process for determining whether or not the pumped water flow rate is periodically reduced based on the output signal of the flow meter; a third process of controlling the flow control valve to maintain the opening degree of the flow control valve when the determinations of both the first process and the second process are affirmative; a fourth process of controlling the flow control valve to change an opening degree of the flow control valve when at least one of the first process and the second process is determined to be negative; Run The ground improvement device according to claim 10.

12. The control unit a first process for determining whether or not an abnormal sound occurs periodically based on an output signal of the acoustic sensor; a second process for determining whether or not the pumped water flow rate is periodically reduced based on the output signal of the flow meter; a third process of controlling the flow control valve so as to maintain the opening degree of the flow control valve when at least one of the first process and the second process is determined to be positive; a fourth process of controlling the flow control valve to change the opening degree of the flow control valve when both the first process and the second process are negative; Run The ground improvement device according to claim 10.

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