JP6159566B2 - In-situ purification system for contaminated ground using bubbles and iron powder slurry - Google Patents

Description

The present invention relates situ purification oak stem contamination Ground Using bubbles and iron powder slurry.

  An in-situ purification method for purifying contaminants such as VOCs in-situ is known. In this purification method, there is a method in which iron powder slurry is mixed with contaminated ground and the contaminant is purified by reductive decomposition with iron powder. Alternatively, there is one that suppresses the elution of pollutants by the action of iron powder adsorption.

  In this purification method, attempts have been made to mix iron powder evenly and efficiently over a wide range of contaminated ground. For example, in the purification method described in Patent Document 1, compressed air is supplied to an iron powder slurry in which iron oxide powder is dispersed in water, and the iron powder slurry supplied with the compressed air is discharged to the ground. Moreover, in the pressure feeding method described in Patent Document 2, fine bubbles are included in the iron powder slurry containing the thickener, and the iron powder slurry containing the fine bubbles is pressure-fed.

Japanese Patent Laid-Open No. 2005-230667 JP 2004-332230 A

  In the above-described method, the iron powder slurry is also used as a drilling fluid. That is, the friction with the contaminated ground at the time of drilling is reduced by the iron powder slurry. For this reason, when excavating hard ground, the amount of iron powder for purification larger than the amount necessary for purification of the contaminated ground is supplied to the contaminated ground, which is uneconomical. In addition, since a large amount of water is supplied to the contaminated ground, the ground is softened and the amount of mud is increased.

  In order to prevent these problems, there is also a construction method in which the iron powder for purification is air-conveyed in the form of powder and mixed. However, with this method, there is concern about wear of the pressure-feed piping due to iron powder, ground deformation due to the injection of compressed air, etc., and an increase in groundwater level due to the air lift effect.

  The present invention has been made in view of such circumstances, and its main purpose is to mix an appropriate amount of iron powder slurry into the contaminated ground regardless of the hardness of the ground when mixing the iron powder into the contaminated ground. It is to supply.

To achieve the purpose of the pre-mentioned, the present invention is moved together with the ejecting air bubbles and iron powder slurry from the lower end of the stirring rod, the stirring blade provided at the lower end of the stirring rod in the direction of the depth of the contaminated soil An in-situ purification system that stirs the contaminated ground while purifying the contaminated ground in place with iron powder mixed in the contaminated ground, and detects the moving speed of the stirring rod in the depth direction a moving speed detecting section that, the more as the discharge amount of the iron powder slurry decreases the moving speed of the stirring rod is small, have a slurry discharge amount adjusting unit for adjusting the discharge amount of the iron powder slurry, the slurry The discharge amount adjusting unit includes an interlocking pump that sends out the iron powder slurry and a nonmagnetic comparative thickening liquid having a uniform viscosity in the iron powder slurry, and an electromagnetic flowmeter that measures a delivery flow rate of the comparative thickening liquid. Has a delivery rate of said comparison increased mucus, characterized by a discharge amount of the iron powder slurry.

According to the present invention, the slurry discharge amount adjusting unit adjusts the discharge amount of the iron powder slurry based on the moving speed in the depth direction of the stirring rod detected by the moving speed detecting unit. That is, when the moving speed is low, the slurry discharge amount adjusting unit decreases the discharge amount of the iron powder slurry by that amount, and increases the discharge amount of the iron powder slurry by that amount when the moving speed increases. Thereby, even if the resistance of the ground changes, an appropriate amount of iron powder slurry can be supplied regardless of the hardness of the contaminated ground. As a result, the iron powder mixing amount per unit depth can be equalized.
In addition, since the delivery flow rate of the non-magnetic comparative thickening liquid is measured with an electromagnetic flow meter and the discharge amount of the iron powder slurry, even if the iron powder slurry is difficult to accurately measure the delivery flow rate with the electromagnetic flow meter, The delivery flow rate can be obtained with high accuracy based on the delivery flow rate of the comparative thickening liquid.

  In the above-described in-situ purification system, a rotational torque measurement unit that measures the rotational torque of the stirring blade, and an adjustment of the bubble discharge amount so that the bubble discharge amount increases as the rotational torque of the stirring blade increases. It is preferable to have a bubble discharge amount adjusting unit. In this purification system, the bubble discharge amount adjusting unit adjusts the bubble discharge amount based on the rotational torque of the stirring blade measured by the rotational torque measuring unit. That is, when the rotational torque is high, the bubble discharge amount is increased by that amount and friction is reduced, and when the rotational torque is lowered, the bubble discharge amount is decreased by that amount. Thereby, even if the resistance at the time of ground stirring changes, an appropriate rotation speed can be maintained without adjusting the supply amount of the iron powder slurry. And since friction is adjusted with the discharge amount of a bubble, the softening of a ground can also be suppressed.

In addition, the present invention discharges bubbles and iron powder slurry from the lower end of the stirring rod and stirs the contaminated ground while moving the stirring blade provided at the lower end of the stirring rod in the depth direction of the contaminated ground. And an in-situ purification system that purifies the contaminated ground in place with iron powder mixed in the contaminated ground, and a moving speed detection unit that detects a moving speed of the stirring rod in the depth direction; The iron powder delivered by a separate system, having a slurry discharge amount adjusting unit that adjusts the discharge amount of the iron powder slurry so that the discharge amount of the iron powder slurry decreases as the moving speed of the stirring rod decreases. A merging portion for merging the slurry and the bubbles is provided immediately before the upper end of the stirring rod . In this purification system, since the iron powder slurry and the bubbles are joined just before the upper end of the stirring rod, the bubbles are not easily lost, and the burden due to the pressure rise to the bubble pumping portion can be suppressed. Furthermore, the homogeneous mixing state of air bubbles and iron powder slurry can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, when mixing iron powder with a contaminated ground and purifying a contaminant in-situ, an appropriate quantity of iron powder slurry can be supplied irrespective of the hardness of a contaminated ground.

It is a block diagram explaining the structure of an in-situ purification system. It is a block diagram explaining the structure of a bubble pumping part. It is a block diagram explaining the structure of a slurry pumping part. It is a side view explaining the structure of a purification construction machine. It is a perspective view explaining a stirring blade. It is sectional drawing explaining the internal structure of a line mixer. It is a block diagram explaining the principal part of a purification construction machine. It is a block diagram explaining the structure of a sequencer board. It is a flowchart explaining iron powder slurry discharge amount control. It is a flowchart explaining the discharge amount control of a bubble. It is a chart at the time of construction of drilling speed and rotational torque. It is a figure explaining a ground purification work typically.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the configuration of the in-situ purification system 1 will be described with reference to FIG. The in-situ purification system 1 includes a pressure feeding device 2, a purification construction machine 3, a sequencer panel 4, a monitor 5, and a tablet terminal 6.

  The pressure feeding device 2 is a device that manufactures, stores, and pumps iron powder slurry and bubbles. This pumping device 2 is connected to the sequencer panel 4 so as to be communicable, and adjusts the discharge amount of iron powder slurry and bubbles according to the control information transmitted from the sequencer panel 4. Further, the pressure feeding device 2 transmits information indicating the discharge amount of iron powder slurry and bubbles to the sequencer panel 4. The pressure feeding device 2 will be described in detail later.

  The purification construction machine 3 is an apparatus that excavates the contaminated ground G to be purified and mixes the iron powder slurry and bubbles sent from the pressure feeding device 2 with the contaminated ground G. For this reason, it has a stirring rod 14 and a stirring blade 15. Then, when purifying the contaminated ground G, the stirring blade 15 attached to the lower end of the stirring rod 14 is rotated while moving the stirring rod 14 in the depth direction of the ground, and the iron is fed from the lower end of the stirring rod 14. Powder slurry and bubbles are discharged. The discharged iron powder slurry and air bubbles are injected into the contaminated ground G. And the contaminated ground G in which the iron powder slurry etc. were inject | poured is stirred in the depth direction, and iron powder is mixed with this ground G.

  At the time of purification of the contaminated ground G, the purification construction machine 3 transmits information relating to the moving amount of the stirring rod 14 and information relating to the rotational torque of the stirring blade 15 to the sequencer board 4. The purification construction machine 3 will also be described in detail later.

  The sequencer panel 4 is a central part of control in the in-situ purification system 1 and is operated by an operator. The sequencer panel 4 is connected to the pressure feeding device 2, the purification construction machine 3, and the tablet terminal 6 so as to be communicable (wireless communication or wired communication), and collects necessary information and transmits control information. . The sequencer board 4 will be described in detail later.

  The monitor 5 is electrically connected to the sequencer board 4 and displays information necessary for operations on the sequencer board 4. The tablet terminal 6 is communicably connected to the sequencer panel 4 and displays various information such as the discharge amount of iron powder slurry and bubbles, the amount of movement of the stirring rod 14, and the rotational torque of the stirring blade 15.

  Next, the pressure feeding device 2 will be described in detail. As shown in FIG. 1, the pumping device 2 includes a bubble pumping unit 21, a slurry pumping unit 22, and a pumping side communication unit 23. The bubble pumping unit 21 is a part that foams a foaming material to produce bubbles, and pumps the produced bubbles. The slurry pumping unit 22 is a part that manufactures an iron powder slurry from iron powder, water, and a thickener, and pumps the manufactured iron powder slurry. The pressure-feed-side communication unit 23 is a part that communicates with the sequencer board 4 and transmits and receives various types of information. That is, the bubble pumping unit 21 and the slurry pumping unit 22 transmit and receive information via the pumping side communication unit 23.

  As shown in FIG. 2, the bubble pumping unit 21 includes a foaming material storage unit 31, a foaming material pump 32, a compressor 33, a bubble control device 34, and a foaming device 35. The foaming material storage unit 31 is a container that stores the foaming material. The foaming material pump 32 is a part that sends the foaming material stored in the foaming material storage unit 31 to the bubble control device 34. The compressor 33 is a part that compresses air to obtain compressed air. The bubble control device 34 is a portion that supplies the foaming material sent from the foaming material pump 32 and the compressed air supplied from the compressor 33 to the foaming device 35. The foaming device 35 is a part that foams a foaming material using compressed air to produce bubbles and pumps the produced bubbles.

  In the bubble pumping unit 21, the bubble control device 34 controls the supply amount and supply pressure of the foaming material and compressed air supplied to the foaming device 35. Thereby, the foaming ratio of foaming material and the delivery pressure of a bubble are adjusted. The bubble delivery pressure defines the amount of bubbles discharged from the lower end of the stirring rod 14. That is, the bubble discharge amount can be adjusted according to the delivery pressure. In addition, the delivery pressure in the bubble pressure delivery unit 21 is controlled by a sequence control unit 51 (see FIG. 8) included in the sequencer panel 4. For this reason, the set of the bubble pressure sending unit 21 and the sequence control unit 51 corresponds to a bubble discharge amount adjusting unit.

  As shown in FIG. 3, the slurry pumping unit 22 includes a slurry storage unit 41, a thickened liquid storage unit 42, a two-liquid interlocking pump 43, and a flow rate measurement unit 44.

  The slurry storage unit 41 is a part that manufactures and stores an iron powder slurry, and includes a manufacturing container, a storage container, a slurry pump, and the like (all not shown). And iron powder, water, and a thickener are thrown into a container for manufacture, and an iron powder slurry is manufactured by stirring with a mixer. The iron powder slurry to be manufactured is one whose iron powder concentration is adjusted according to construction conditions such as pollutants and concentration, and has a high concentration in terms of suppressing the amount of mud when supplying to the ground G (iron A powder concentrated slurry) is desirable. The produced iron powder slurry is transferred to a storage container by a slurry pump. The thickening liquid reservoir 42 is a container for storing a nonmagnetic and conductive comparative thickening liquid whose viscosity is equal to that of the iron powder slurry. This comparative thickening liquid is manufactured by, for example, dissolving the thickener used in manufacturing the iron powder slurry in water.

  The two-liquid interlocking pump 43 is a device that pumps the iron powder slurry stored in the slurry storage unit 41 and the comparative thickening solution stored in the thickening solution storage unit 42 individually to the flow rate measurement unit 44 at the same flow rate. . The flow rate measuring unit 44 is a part that measures the flow rate of the iron powder slurry and the comparative thickening liquid, and the first electromagnetic flow meter 44a that measures the flow rate of the iron powder slurry and the second electromagnetic flow meter that measures the flow rate of the comparative thickening liquid. 44b. These electromagnetic flowmeters 44a and 44b utilize a phenomenon in which when a conductive liquid (iron powder slurry or thickening liquid) flows in an electromagnetic field, an electromotive force proportional to the flow velocity is generated in a direction perpendicular to the flow. The flow rate of the conductive liquid is measured.

  In the slurry pumping unit 22, the flow rate of the iron powder slurry is measured by the first electromagnetic flow meter 44a. However, if a magnetic material such as iron powder is included, a measurement error increases. Therefore, in this embodiment, in addition to the iron powder slurry, a comparative thickening liquid is manufactured, and the iron powder slurry and the comparative thickening liquid are pumped under the same conditions by the two-liquid interlocking pump 43, and the flow rate of the comparative thickening liquid is 2 Measured with an electromagnetic flow meter 44b.

  Thereby, the flow volume of an iron powder slurry is manageable with the flow volume of the comparative thickening liquid measured with the 2nd electromagnetic flowmeter 44b. That is, the measurement result by the first electromagnetic flow meter 44a is used for the purpose of determining whether or not the iron powder slurry is being pumped on the assumption that an error due to the iron powder is included. And the measurement result in the 2nd electromagnetic flowmeter 44b is acquired as a flow rate of iron powder slurry. Thereby, the delivery flow rate of iron powder slurry can be acquired with high accuracy. The feed flow rate of the iron powder slurry is fed back to the sequence control unit 51 in order to control the operation of the two-liquid interlocking pump 43.

  The iron powder slurry whose flow rate has been measured by the first electromagnetic flow meter 44a is supplied from the lower end of the stirring rod 14 after being supplied to the purification construction machine 3 and injected into the contaminated ground G. Therefore, the flow rate of the iron powder slurry corresponds to the discharge amount of the iron powder slurry from the stirring rod 14. Since the delivery flow rate of the iron powder slurry is adjusted by a control signal from the sequence control unit 51, the set of the two-liquid interlocking pump 43 and the sequence control unit 51 corresponds to the slurry discharge amount adjustment unit. On the other hand, the comparative thickening liquid whose flow rate is measured by the second electromagnetic flow meter 44b is returned to the thickening liquid storage section 42 and circulated for use.

  Next, the purification construction machine 3 will be described in detail. As shown in FIG. 4, the purification construction machine 3 includes a main body 11, a leader 12, a stirring auger 13, a stirring rod 14, a stirring blade 15, a merge pipe 16, a line mixer 17, a distance sensor 18, and a torque measuring unit 19. Have.

  The main body 11 is provided with a driver's seat 11a where an operator is seated, a moving caterpillar 11b, an engine (not shown), and the like. The leader 12 is a member that supports the stirring rod 14 movably along the vertical direction. The leader 12 is attached to the front of the main body 11 by a stay 12a or the like. The stirring auger 13 is a part that generates power for rotating the stirring rod 14. The stirring auger 13 moves up and down along the leader 12 as the stirring rod 14 moves.

  The stirring rod 14 is constituted by a cylindrical steel pipe. And the stirring blade 15 is attached to the lower end part of the stirring rod 14, and the swivel joint 14a is attached to the upper end part. The swivel joint 14a is supplied with a mixture of bubbles and iron powder slurry from the line mixer 17 (hereinafter also referred to as bubble slurry). Then, the bubble slurry supplied to the swivel joint 14a flows down inside the stirring rod 14 and is discharged to the contaminated ground G.

  As shown in FIG. 5, the stirring blade 15 has a propeller shape, and a plurality of stirring blades 15 are attached in the axial direction of the stirring rod 14. In the present embodiment, three propeller members 15 a to 15 c are attached to the stirring rod 14. Further, a discharge port is provided in the vicinity of the lower end of the stirring rod 14, and the bubble slurry is discharged from the lower end portion of the stirring rod and injected into the ground G.

  As shown in FIG. 1, the merging pipe 16 is a part that joins the bubbles sent from the pressure feeding device 2 through the bubble supply pipe 7A and the iron powder slurry sent from the pressure feeding device 2 through the slurry supply pipe 7B, For example, it is composed of a Y-shaped tube or a T-shaped tube. The joining pipe 16 is provided immediately before the swivel joint 14 a together with the line mixer 17, and bubbles and iron powder slurry are joined before the stirring rod 14. Such a merging pipe 16 corresponds to a merging portion for merging the bubbles and iron powder slurry sent out by another system.

  The line mixer 17 is disposed between the merging pipe 16 and the swivel joint 14a, and is a part that mixes the bubbles after the merging and the iron powder slurry to form a bubble slurry. Various types of line mixers 17 can be used. For example, as shown in FIG. 6A, a plurality of baffle plates 17b may be alternately arranged inside the tube 17a. Moreover, as shown in FIG.6 (b), you may arrange | position the screw member 17c inside the pipe | tube 17a.

  And in this embodiment, since air bubbles and iron powder slurry are sent out by another system and merged and mixed just before being supplied to the upper end of the stirring rod 14, the air bubbles are hardly lost. This is because, after the mixing, the moving distance until the stirring rod 14 is supplied is short, so that bubbles having a small specific gravity are difficult to be crushed by the iron powder slurry having a large specific gravity. Moreover, since the bubble slurry falls by its own weight after being supplied to the stirring rod 14, it is possible to prevent the bubbles from being crushed. Thereby, the burden of the bubble pumping part 21 by a pressure rise can be suppressed. Furthermore, the homogeneous mixing state of air bubbles and iron powder slurry can be maintained.

  In addition, when bubble slurry is produced and pumped by the pumping device 2, the bubbles are crushed and energy is partially accumulated. When the accumulated energy is released, it also serves as power for pushing out the bubble slurry. Therefore, pulsation may occur in the bubble slurry by repeatedly storing and releasing energy. In particular, since the bubble slurry is supplied from the upper end portion of the stirring rod 14, the self-weight acts during the raising of the bubble slurry to the upper end portion of the stirring rod 14, and the bubbles easily collapse. As a result, pulsation is more likely to occur. On the other hand, in this embodiment, since the air bubbles and the iron powder slurry are mixed immediately before being supplied to the stirring rod 14, the pulsation of the iron powder slurry can be effectively suppressed.

  FIG. 7 is a block diagram for explaining a main part of the purification construction machine 3. As shown in this figure, the purification construction machine 3 is provided with a distance sensor 18, a torque measuring unit 19, and a heavy equipment side communication unit 20.

  The distance sensor 18 detects the moving distance of the stirring rod 14 in the depth direction. For example, as shown in FIG. 4, the distance sensor 18 is provided in each of the leader 12 and the stirring auger 13. That is, the fixed sensor 18 a is attached to a predetermined position of the reader 12, and the movable sensor 18 b is attached to the stirring auger 13. As described above, since the stirring auger 13 moves in the vertical direction together with the stirring rod 14, the moving distance in the depth direction of the stirring rod 14 is recognized by measuring the downward moving distance of the stirring auger 13. it can.

  The torque measuring unit 19 corresponds to a rotational torque measuring unit and measures the rotational torque of the stirring blade 15. In the present embodiment, the rotational torque of the drive motor M that rotates the stirring blade 15 is acquired as the rotational torque of the stirring blade 15. And when the drive motor M is an electric motor, the torque measurement part 19 is comprised by the current sensor which measures the electric current value supplied to an electric motor. That is, since the purification construction machine 3 performs control to rotate the stirring blade 15 at a specified speed, the current supplied to the electric motor is proportional to the torque of the electric motor. For this reason, the current supplied to the electric motor is measured. On the other hand, when the drive motor M is a hydraulic motor, the torque measurement unit 19 is configured by a hydraulic sensor that measures the pressure of the drive oil supplied to the hydraulic motor. That is, since the pressure of the driving oil supplied to the hydraulic motor is proportional to the torque of the hydraulic motor, the pressure of the driving oil is measured.

  The heavy equipment side communication unit 20 is a part that communicates with the sequencer panel 4 and transmits various information. That is, the moving distance information of the stirring rod 14 acquired by the distance sensor 18 and the rotational torque information of the stirring blade 15 acquired by the torque measuring unit 19 are transmitted to the sequencer panel 4. The movement distance information is used when the movement speed of the stirring rod 14 is calculated by the sequence control unit 51 (see FIG. 8) of the sequencer board 4. For this reason, the set of the distance sensor 18 and the sequence control unit 51 corresponds to a moving speed detection unit that detects the moving speed of the stirring rod 14 in the depth direction.

  Next, the sequencer board 4 will be described. As shown in FIG. 8, the sequencer board 4 includes a sequence control unit 51, a control side communication unit 52, and an input unit 53. The sequence control unit 51 includes a CPU 54 and a memory 55. The CPU 54 reads out a sequence program stored in the memory 55 and performs sequence control. The moving speed of the stirring rod 14 is calculated based on the moving distance information of the stirring rod 14 detected by the distance sensor 18. The control-side communication unit 52 communicates with the pressure-feeding-side communication unit 23 of the pressure-feeding device 2 and the heavy equipment-side communication unit 20 of the purification construction machine 3 to transmit and receive information. The input unit 53 is, for example, a keyboard, a touch panel, or a mouse, and is operated by an operator.

  Hereinafter, the sequence control by the sequence control unit 51 will be described. This in-situ purification system 1 is characterized by iron powder slurry and bubble discharge amount control according to the hardness of the ground G. For this reason, iron powder slurry discharge amount control and bubble discharge amount control will be described.

  First, the discharge amount control of the iron powder slurry will be described with reference to the flowchart of FIG. In this discharge amount control, the sequence control unit 51 first sets the standard slurry injection amount ISs and the maximum excavation speed Vs (S1).

  Here, the standard slurry injection amount ISs is the injection amount of the iron powder slurry to the contaminated ground G determined according to the concentration of the contaminant. Here, the entire amount of the iron powder slurry and bubbles discharged from the lower end of the stirring rod 14 is injected into the contaminated ground G. For this reason, the injection amount to the contaminated ground G matches the discharge amount from the stirring rod 14.

  The maximum excavation speed Vs is an excavation speed in the depth direction corresponding to the standard slurry injection amount ISs. That is, when the iron powder slurry is injected at the standard slurry injection amount ISs while moving the stirring rod 14 in the depth direction at the maximum excavation speed Vs, an amount of iron powder suitable for the contaminated ground G is mixed into the contaminated ground G. The In the following discharge amount control, the excavation speed of the stirring rod 14 is controlled so as not to exceed the maximum excavation speed Vs.

  Next, the sequence control unit 51 sets i = 0 as an initial value for the control step i in the excavation control (S2). Similarly, the standard slurry injection amount ISs is set as the injection amount of the iron powder slurry (S3). If these values are set, the sequence control unit 51 activates the slurry pressure feeding unit 22 (S4). At this time, the sequence control unit 51 transmits a control signal indicating that the injection amount of the iron powder slurry is the standard slurry injection amount ISs to the slurry pumping unit 22.

  At this time, the purification construction machine 3 is excavating the ground G to a predetermined depth. Further, as will be described later, bubble feeding is started in synchronization with the start of feeding of the iron powder slurry. For this reason, bubble slurry is discharged from the lower end of the stirring rod 14 and injected into the ground G.

  Next, the sequence control unit 51 measures the moving speed Vi in the depth direction of the stirring rod 14 (S5). That is, the sequence control unit 51 obtains the moving speed of the stirring rod 14 based on the moving distance information of the stirring rod 14 periodically transmitted from the purification construction machine 3 (distance sensor 18). Then, based on the obtained moving speed Vi, it is determined whether or not the moving speed Vi has decreased from the previous moving speed Vi (S6). Here, when the moving speed Vi decreases, it is understood that the hard contaminated ground G is excavated, and therefore the sequence control unit 51 reduces the pumping amount by which the pumping amount of the iron powder slurry is reduced by the unit control amount. The signal is transmitted to the pressure feeding device 2 (slurry pressure feeding unit 22) (S7). Thereby, the pumping amount of the iron powder slurry is reduced by the unit control amount.

  On the other hand, when the obtained moving speed Vi has not decreased from the previous moving speed Vi, the sequence control unit 51 determines whether or not the obtained moving speed Vi has increased from the previous moving speed Vi (S8). And when the moving speed Vi is increasing, it is understood that the contaminated ground G softer than before is excavated, so the sequence control unit 51 increases the pumping amount of the iron powder slurry by the unit control amount. A pumping amount increase signal is transmitted to the pumping device 2 (slurry pumping unit 22) (S9). Thereby, the pumping amount of the iron powder slurry is increased by the unit control amount.

  Next, the sequence control unit 51 determines whether or not the step update timing has come (S10). Here, when the step update timing has not yet arrived, it returns to step S4 and repeats the above-mentioned process. On the other hand, when the step update timing has arrived, the sequence control unit 51 determines whether or not the current step is the final step (S11). If it is determined that the step is not the final step, the sequence value is incremented ( +1 update) (S12), and the injection amount of the iron powder slurry is updated (S13). Then, the process proceeds to step S4, and the control with the updated injection amount is performed in the same manner. If it is determined as the final step, the series of processing ends.

  Next, bubble discharge amount control will be described with reference to the flowchart of FIG. In this discharge amount control, the sequence control unit 51 first sets the standard bubble injection amount Bs and the reference stirring torque Tc (S21).

  Here, the standard bubble injection amount Bs is a standard bubble injection amount determined according to the hardness of the contaminated ground G. The reference stirring torque Tc is also a standard rotational torque determined according to the hardness of the contaminated ground G. That is, in the case of the target contaminated ground G, appropriate construction can be performed by injecting bubbles with the standard bubble injection amount Bs and rotating the stirring blade 15 with the reference stirring torque Tc.

  Next, the sequence control part 51 sets i = 0 as an initial value regarding the control step i in excavation control (S22). Similarly, the standard bubble injection amount Bs is set as the bubble injection amount (S23). If these values are set, the sequence control unit 51 activates the bubble pumping unit 21 (S24). Here, the sequence control unit 51 transmits a control signal indicating that the bubble injection amount is the standard bubble injection amount Bs to the bubble pumping unit 21. Thereby, bubble slurry is discharged from the lower end of the stirring rod 14 and injected into the ground G.

  Next, the sequence control unit 51 measures the rotational torque Ti of the stirring blade 15 (S25). That is, the sequence control unit 51 acquires the rotational torque Ti of the stirring blade 15 based on the rotational torque information periodically transmitted from the purification construction machine 3 (torque measurement unit 19). Then, the obtained rotational torque Ti is compared with the reference stirring torque Tc (S26). If the rotational torque Ti is larger than the reference stirring torque Tc, it is understood that the contaminated ground G having a large resistance is being stirred. The sequence control unit 51 transmits a bubble amount increase signal for increasing the bubble pumping amount by the unit control amount to the pumping device 2 (bubble pumping unit 21) (S27).

  On the other hand, when the rotational torque Ti is equal to or less than the reference stirring torque Tc, the sequence control unit 51 determines whether or not the bubble injection amount Bi at that time is larger than the standard bubble injection amount Bs (S28). If the bubble injection amount Bi is larger than the standard bubble injection amount Bs, the sequence control unit 51 transmits a bubble amount reduction signal for reducing the bubble pumping amount by the unit control amount to the pumping device 2 (bubble pumping unit 21). (S9). Thereby, the pumping amount of bubbles is reduced by the unit control amount.

  Next, the sequence control unit 51 determines whether or not the step update timing has come (S30). If the step update timing has not yet arrived, the process returns to step S24 and the above-described processing is repeated. On the other hand, when the step update timing has arrived, the sequence control unit 51 determines whether or not the current step is the final step (S31). If it is determined that the step is not the final step, the sequence value is incremented ( +1 update) (S32), and the bubble injection amount Bi is also updated (S33). Then, the process proceeds to step S24, and the control with the updated injection amount is performed in the same manner. If it is determined as the final step, the series of processing ends.

  By performing the above control, as the iron powder slurry is reduced in the amount of injection as the moving speed Vi of the stirring rod 14 decreases, the iron powder mixing amount per unit volume is equalized regardless of the hardness of the contaminated ground G. Can be On the other hand, as for the bubbles, the larger the rotational torque Ti, the larger the injection amount. Therefore, the friction between the stirring blade 15 and the contaminated ground G can be reduced, and excavation can be performed while equalizing the rotational torque.

  Here, FIG. 11 is a chart at the time of construction of the drilling speed and rotational torque, (a) is a chart of roughing (bubbles 0%), (b) is a chart when 30% of bubbles are added, (c). Is a chart when 50% of bubbles are added. In all cases, the same ground G is excavated.

  In the excavation, even when the rotational torque reached the upper limit value T1 of the purification construction machine 3, excavation was possible only up to the depth D1 (for example, time t1). On the other hand, it was confirmed that by adding air bubbles of 30% or more of the earth and sand volume, the maximum value of the rotational torque can be suppressed to T2 and T3 smaller than the upper limit value T1, and excavation can be performed to double depths D2 and D3. (For example, time t2, t3). At that time, it was also confirmed that the rotational torque required for stirring can be reduced by further increasing the amount of bubbles added. This indicates that the adjustment of the bubble addition amount is effective for adjusting the rotational torque during stirring.

  As is clear from the above description, in the in-situ purification system 1 of the present embodiment, the moving speed detecting step (S5) for detecting the moving speed of the stirring rod 14 in the depth direction and the moving speed of the stirring rod 14 are determined. Accordingly, a slurry discharge amount adjusting step (S6 to S9) for adjusting the discharge amount of the iron powder slurry is performed. Thereby, for example, as shown in FIG. 12, when purifying the contaminated ground G in which the second ground layer G2 harder than the first ground layer G1 is formed between the first ground layers G1 and G1 of normal hardness, When mixing foam slurry with the earth and sand of the two formations G2, the discharge amount (injection amount) of the iron powder slurry is reduced, so even if the hardness of the contaminated ground G changes, it is appropriate regardless of this hardness. An amount of iron powder slurry can be supplied. As a result, the iron powder mixing amount per unit depth (unit volume) can be equalized.

  Further, in the in-situ purification system 1, a rotational torque measuring step (S 25) for measuring the rotational torque of the stirring blade 15, and a bubble discharge amount adjustment for adjusting the discharge amount of the bubbles according to the rotational torque of the stirring blade 15. Steps (S26 to S29) are performed. As a result, when the foam slurry is mixed with the earth and sand of the second formation, the discharge amount (injection amount) of the bubbles is increased. Therefore, even if the hardness of the ground G changes, the stirring blade 15 is appropriately rotated. Can be rotated at speed. That is, when the rotational torque is high, the bubble discharge amount is increased by that amount and friction is reduced, and when the rotational torque is lowered, the bubble discharge amount is decreased by that amount. Thereby, even if the resistance at the time of ground stirring changes, an appropriate rotation speed can be maintained without adjusting the discharge amount of the iron powder slurry. And since friction is adjusted with the discharge amount of a bubble, the softening of the ground G can also be suppressed.

  The above description of the embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof. For example, you may comprise as follows.

  In the above-described embodiment, iron powder slurry and air bubbles are mixed and used, but at least the amount of iron powder slurry is adjusted according to the hardness of the ground G, thereby equalizing the amount of iron powder mixed. can do. In this case, a material other than bubbles may be used as the friction reducing material.

  Regarding the mixing of the iron powder slurry and the bubbles, in the above-described embodiment, the mixing is performed immediately before the upper end of the stirring rod 14. Also good. In the above-described embodiment, the joining pipe 16 is provided to mix the iron powder slurry and air bubbles. However, if the construction machine (double pipe or the like) can pressure-feed the two-liquid pipe to the discharge port, the joining pipe 16 is used. Can be omitted.

  The iron powder slurry is exemplified by the addition of a thickener, but may be iron powder dispersed in water, iron powder (as powder) or colloidal iron powder.

  Regarding the pressure control of the iron powder slurry, in the above-described embodiment, the first electromagnetic flow meter 44a and the second electromagnetic flow meter 44b are used. However, only the second electromagnetic flow meter 44b may be provided for control. Further, in the above-described embodiment, the comparative thickening liquid is circulated and the control is performed based on the flow rate of the comparative thickening liquid. However, if there is a flow meter that can accurately measure the flow rate of the iron powder slurry, it may be used. .

DESCRIPTION OF SYMBOLS 1 ... In-situ purification system, 2 ... Pressure feeder, 3 ... Purification machine, 4 ... Sequencer board, 5 ... Monitor, 6 ... Tablet terminal, 7A ... Bubble supply pipe, 7B ... Slurry supply pipe, 11 ... Purification machine Main part, 11a ... Driver's seat, 11b ... Caterpillar, 12 ... Leader, 12a ... Stay, 13 ... Agitation auger, 14 ... Agitation rod, 14a ... Swivel joint, 15 ... Agitation blade, 15a-15c ... Propeller member, 16 ... Merge Pipe, 17 ... Line mixer, 17a ... Pipe, 17b ... Baffle plate, 17c ... Screw member, 18 ... Distance sensor, 18a ... Fixed side sensor, 18b ... Movable side sensor, 19 ... Torque measuring unit, 20 ... Heavy equipment side communication unit , 21 ... Bubble pressure feeding part, 22 ... Slurry pressure feeding part, 23 ... Pressure feeding side communication part, 31 ... Foaming material storage part, 32 ... Foaming material pump, 33 ... Compressor, 34 ... Foam control device, 35 ... foaming device, 41 ... slurry storage unit, 42 ... thickening liquid storage unit, 43 ... two-liquid interlocking pump, 44 ... flow rate measurement unit, 44a ... first electromagnetic flow meter, 44b ... second electromagnetic flow rate 51 ... Sequence control unit 52 ... Control side communication unit 53 ... Input unit G ... Contaminated ground G1 ... First formation G2 ... Second formation M ... Stirring blade drive motor

Claims (4)

Air bubbles and iron powder slurry are discharged from the lower end of the stirring rod, and the contaminated ground is stirred while moving the stirring blade provided at the lower end of the stirring rod in the depth direction of the contaminated ground. An in-situ purification system that purifies the contaminated ground in-situ with mixed iron powder,
A moving speed detector for detecting the moving speed of the stirring rod in the depth direction;
The stirring as discharge amount of the more mobile speed is smaller the iron powder slurry of the rod is reduced, have a slurry discharge amount adjusting unit for adjusting the discharge amount of the iron powder slurry,
The slurry discharge amount adjusting unit is
An interlocking pump that delivers a non-magnetic comparative thickening liquid having a uniform viscosity in the iron powder slurry and the iron powder slurry;
An electromagnetic flow meter for measuring the delivery flow rate of the comparative thickening liquid,
The in-situ purification system characterized in that the flow rate of the comparative thickening liquid is the discharge amount of the iron powder slurry . A rotational torque measuring unit for measuring the rotational torque of the stirring blade;
Wherein as the rotational torque of the stirring blade is much discharge amount of higher the bubble, situ purifying system according to claim 1, characterized in that it comprises a bubble discharge amount adjusting unit for adjusting the discharge amount of the bubble . Air bubbles and iron powder slurry are discharged from the lower end of the stirring rod, and the contaminated ground is stirred while moving the stirring blade provided at the lower end of the stirring rod in the depth direction of the contaminated ground. An in-situ purification system that purifies the contaminated ground in-situ with mixed iron powder,
A moving speed detector for detecting the moving speed of the stirring rod in the depth direction;
The stirring as discharge amount of the more mobile speed is smaller the iron powder slurry of the rod is reduced, have a slurry discharge amount adjusting unit for adjusting the discharge amount of the iron powder slurry,
An in-situ purification system characterized in that a merging section for merging the iron powder slurry and the bubbles sent out by another system is provided immediately before the upper end of the stirring rod . A rotational torque measuring unit for measuring the rotational torque of the stirring blade;
The in-situ purification system according to claim 3 , further comprising a bubble discharge amount adjustment unit that adjusts the discharge amount of the bubbles such that the discharge amount of the bubbles increases as the rotational torque of the stirring blade increases. .

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