JPH10114937A - Electric infiltration dehydration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength of a ground on average by an electric infiltration dehydration method wherein a large quantity of underground water is dehydrated in a shorter time from a soft viscous ground compared with a conventional method and on average, the moisture content of a ground is decreased. SOLUTION: A direct current having pressure being as high as possible is energized between a pair of electrodes 14 and 15 erected in a ground 19. This constitution collects underground water to the electrode 14 on the anode side and dehydration from the electrode 14 is effected. In which case, by converting polarities of the electrodes 14 and 15 at a period at which a dehydration speed from the electrode 14 is reduced, underground water gathers at the electrode 15 and dehydration from the electrode 15 is effected. Thus, a large quantity of underground water is dehydrated from the ground 19 in a short time, and on average, the moisture content of the ground 19 is reduced and on average, the strength of the ground is improved along with reduction of the moisture content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electroosmotic dehydration of ground, and more particularly, to a method in which a direct current is applied to a pair of electrodes installed at intervals in, for example, silt or clay ground. The present invention relates to an electroosmotic dewatering method for a ground which aims to improve the strength of the ground by moving groundwater in the ground to a collecting-side electrode and drain the groundwater, or to lower the water content ratio of a soil material.

[0002]

2. Description of the Related Art There are a plurality of types of dewatering methods for dewatering the ground. Which dewatering method is to be employed is determined from a cumulative particle diameter curve of soil particles.

In general, a gravity drainage method such as a deep well is used for a ground having relatively good permeability formed of sand, gravel or the like. In addition, a suction drainage method such as a well point is used for a ground having poor water permeability such as silt or clay. When the ground is formed by viscous soil having further poor water permeability, a so-called electroosmotic dewatering method is employed. This electroosmosis dewatering method is to place a pair of electrodes in a soft silt or clay ground that is going to be dewatered, apply a direct current between the two electrodes to generate electroosmosis, and collect water by this electroosmosis. The groundwater collected at the electrode on the side is drained to improve the strength of the ground or to reduce the water content of the soil material.

[0004] Generally, the charged state (interface potential) on the surface of soil particles on the ground is negative. For this reason, the electrode used as a cathode becomes an electrode on the water collecting side. However, the charged state of the soil particle surface may be positive depending on external conditions such as clay minerals and pH in the ground. In this case, the electrode serving as the anode is the electrode on the water collecting side.

In the electroosmotic dewatering method, when the charged state of the soil particles on the ground is negative, a ground electroosmotic dewatering apparatus 1 as shown in FIG. 9 is generally used. The electroosmotic dewatering apparatus 1 has an anode 2, a cathode 3, a power supply 7, and a vacuum pump 8.

[0006] A reinforcing rod is used for the anode 2, and a metal tube having a drain hole 4 at one end is used for the cathode 3.
The anode 2 is placed directly on the ground 5, the cathode 3 is placed on a sand pile 6 formed on the ground 5 with one end facing downward, and the other end is connected to a vacuum pump 8. These anodes 2
The cathode 3 is connected to a power supply 7.

According to such an electroosmotic dehydrator 1,
When a direct current is applied between the anode 2 and the cathode 3 by the power source 7, groundwater in the ground 5 moves from the anode 2 into the sand pile 6 on the cathode 3 side by electroosmosis, and is discharged through the drain hole 4 of the cathode 3. And is pumped up by the vacuum pump 8. In this manner, the ground 5 is dehydrated.

[0008]

However, the conventional ground electroosmotic dewatering apparatus 1 described above has the following problems. That is, when the groundwater existing in the ground 5 is dehydrated by the operation of the electroosmotic dewatering device 1, the water content in the ground 5 is lower around the anode 3 than in the state before dehydration, as shown in FIG. In the vicinity of the cathode 3, the characteristics are improved as compared with the state before the dehydration.

Therefore, as shown in FIG.
However, there is a problem that the strength of the ground 5 around the anode 2 is lower than that before dehydration, but the strength around the cathode 3 is lower than that before dehydration.

The groundwater that has moved to the cathode 3 side and collected in the sand pile 6 flows downward by the highly drainable sand, and flows into the inside of the cathode 3 from the drain hole 4 below the cathode 3. For this reason, the part located above the groundwater level of the sand pile 6 dries and becomes an insulator. Thereby, the anode 2 and the cathode 3
There is also a problem that the electrode function of the above-mentioned electrode is reduced, and the effect of collecting water on the cathode 3 side is reduced.

Further, when the ground is soft clayey soil, etc., since the moving speed of the groundwater in the ground is relatively slow, it takes a long time to dewater the ground by the electroosmotic dewatering apparatus 1 described above. There was also a problem.

It is an object of the present invention to provide a method of electroosmotic dewatering of ground, in which the water content of the ground is averagely reduced in a shorter time than in the prior art, and the strength of the ground is averagely improved.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a direct current is applied to a pair of electrodes installed in the ground at an interval, and groundwater in the ground is moved to a drainage-side electrode for drainage. This is a method of electroosmotic dewatering of the ground for improving the strength of the ground, and is configured as follows in order to solve the above-mentioned technical problem.

That is, in the method of electroosmotic dewatering of the ground according to the present invention, the pair of electrodes is constituted by a cylindrical body having a hole for inflow of groundwater on the outer peripheral surface, and the outer peripheral surface of the cylindrical body is closely attached to the ground. Applying a direct current between the pair of electrodes, moving the groundwater to the collecting-side electrode, draining the groundwater collected inside the collecting-side electrode, The polarity of the pair of electrodes is converted at a time when the dehydration rate is reduced after the start of direct current application between the pair of electrodes, and the direct current is again applied between the pair of electrodes whose polarities have been converted, and the pair of electrodes is turned on. And lowering the groundwater level of the ground in between.

The components of the present invention will be individually described below. The number of holes for inflow of groundwater in the cylindrical body used as the electrode is not limited, but it is preferable to provide a plurality of holes scattered on the outer peripheral surface of the electrode. In this case, the outer diameter of the electrode is 5 to 5.
It is preferable to use a thing of 6 inches and a wall thickness of 3 to 5 mm, place an installation interval of 2 to 5 m, and push in the electrode while digging the inside of the electrode arranged on the ground with an auger. . The material of the cylindrical body may be a conductor, but is preferably a metal such as steel or iron.

The direct current flowing between the pair of electrodes may be supplied from a direct current source such as a direct current generator or the like, and may be supplied by a combination of a commercial power source and a rectifier, or a direct current source by a combination of an alternating current generator and a rectifier. It may be supplied from a device. Further, it is preferable to apply a DC voltage as high as possible when applying a DC voltage between the pair of electrodes, since it is possible to increase the amount of groundwater dewatered from the ground. Specifically, the driving interval between the pair of electrodes is 2 to 5
m, the voltage gradient between the pair of electrodes is 0.5
It is desirable to supply a direct current of V / cm to 5 V / cm.

The above-mentioned dehydration rate is the amount of groundwater discharged per unit time. Further, the time when the dehydration rate decreases after the start of direct current application between the pair of electrodes is defined as follows. That is, dehydration is started by energizing between the pair of electrodes, and each dehydration rate from the start of dehydration (start of energization) to a certain time rapidly increases, reaches a maximum at a certain time, and thereafter It has the characteristic of gradually lowering. Assuming that the maximum dehydration rate in this characteristic is 100%, the time when the maximum dehydration rate decreases from 70% to 50% is defined as the time when the dehydration rate decreases.

The means for draining groundwater may be any as long as the collected groundwater is drained by, for example, pumping it up to the ground. For example, a pump can be used as the drainage means. When a pump is used, it is preferable to use, for example, one of a vacuum pump, a submersible pump, and a manual pump. However, any type of pump may be used as long as it is used for the ground dewatering method.

The polarity of the pair of electrodes may be changed by changing the conducting wire connecting the power supply and the electrodes.
It is preferable from the viewpoint of labor saving that the polarity of the electrode is converted by this on / off using a polarity conversion device.

The polarity conversion device may be of any structure such as a mechanical type, an electrical type or an electronic type as long as the polarity can be converted. Further, the polarity converter may be automatically turned on / off at predetermined time intervals to convert the polarity of the electrode.

The method for electroosmotic dewatering of the ground of the present invention is preferably used for silt or clay ground. In particular, it is preferably used when dewatering a soft clay ground having a high water content.

The method of electroosmotic dewatering of the ground is based on the water content of the ground, the clay mineral, pH, or the target state of improvement, and the like. Can be set or changed as appropriate.

According to such an electroosmotic dewatering method for ground, first, a cylindrical body having a hole for inflow of groundwater on an outer peripheral surface serving as a pair of electrodes is placed in a state where the outer peripheral surface is in close contact with the ground. Cast each one. Next, for example, of the pair of electrodes, one of the electrodes is used as an anode and the other electrode is used as a cathode, and a high-voltage direct current from one electrode to the other electrode is applied between the pair of electrodes. At this time, when the charged state on the surface of the soil particles on the ground is, for example, negative, one electrode becomes an electrode on the non-water collecting side and the other electrode becomes an electrode on the water collecting side.
That is, a water flow that flows from the other electrode to the one electrode is generated in the ground due to electroosmosis, and groundwater in the ground moves toward the other electrode. This groundwater is collected by flowing into the inside of the other electrode from the groundwater inflow hole, and is drained by groundwater drainage means such as a vacuum pump. Thus, the groundwater is dehydrated from the other electrode. As a result, the water content of the ground around one of the electrodes becomes lower than at the start of dehydration.

When the polarity of the electrodes is changed by, for example, switching the polarity switching device at the time when the dehydration rate from the other electrode is reduced, the direction of the direct current flowing between the pair of electrodes is changed from the other electrode to the one electrode. Reverse in the direction toward. Accordingly, the direction of the water flow in the ground is also reversed in the direction from the other electrode toward one electrode. As a result, groundwater in the ground moves to the one electrode side, and is collected inside the one electrode, and is drained by being pumped up by, for example, a vacuum pump or the like.

At this time, the dewatering rate of the groundwater from one electrode maintains substantially the same dehydration rate as that before the dewatering rate of the groundwater on the other electrode side decreases until a certain time elapses. Therefore, a large amount of groundwater is dewatered from the ground in a relatively short time.

Finally, the water content of the ground around the other electrode also decreases, and the groundwater level of the ground between the pair of electrodes is reduced on average, whereby the strength of the ground decreases. It will be in a uniformly improved state.

Further, since the outer peripheral surfaces of the pair of electrodes are placed in close contact with the ground, if the ground is, for example, clay ground, free water may be removed by dewatering the ground by the electroosmotic dewatering method. Only (free water) and a part of the adsorbed water are dehydrated, and the ground around the electrodes is in a wet state. Therefore, the function of the electrode does not deteriorate.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The method for electroosmotic dewatering of ground in the present invention will be described in more detail with reference to the preferred embodiment shown in the drawings. FIG. 1 shows an electroosmotic dewatering device 10 used in the electroosmotic dewatering method of the present invention.

The ground electroosmotic dewatering device 10 includes a power supply 11, a rectifier 12, a polarity switching device 13, a pair of electrodes 14, 15, a vacuum pump 17, and a riser tube 16.
And a water storage tank 18, which is used for dehydration of the soil 19 having high moisture content and soft viscous soil.

The power supply 11 is connected to a rectifier 12 for converting an alternating current to a direct current. The rectifier 12 is connected to a polarity switching device 13, and the polarity switching device 13 is connected to a pair of electrodes 14 and 15, respectively.

The polarity switching device 13 reverses the polarity of the pair of electrodes 14 and 15 by switching the connection between the rectifier 12 and the pair of electrodes 14 and 15. That is, when the polarity switching device 13 is in the “OFF” state, the electrode 15 functions as an anode and the electrode 14 functions as a cathode, and direct current flows in a direction from the electrode 15 to the electrode 14. .

On the other hand, when the polarity switching device 13 is in the "on" state, the electrode 14 functions as an anode and the electrode 15 functions as a cathode, and a direct current flows in a direction from the electrode 14 to the electrode 15. It has been like that.

The pair of electrodes 14 and 15 have the same configuration. Here, the electrode 14 will be described as an example.
Numeral 4 is constituted by a steel cylindrical body, and a plurality of slits 20 as holes for inflow of groundwater existing in the ground 19 are provided on a side wall of the cylindrical body, as shown in FIG. Each slit 20 is provided so as to be scattered along the axial direction of the electrode 14.

The pair of electrodes 14 and 15 are placed at a predetermined position in the ground 19 in a substantially vertical direction at an interval, and the outer peripheral surfaces of the pair of electrodes 14 and 15 and the ground 19 are brought into close contact with each other. I have. The upper portions of the pair of electrodes 14 and 15 are closed by a seal member 22.

The electrodes 14 and 15 are connected to the ground 1
The electrodes 14 and 15 are arranged in the axial direction on the base plate 9, and the electrodes 14 and 15 are pressed into the ground 19 while inserting the augers into the electrodes 14 and 15 and digging the ground 19.

A well point (not shown) is provided at one end of the riser tube 16. This well point has a groundwater inlet and a spherical valve. Also,
This well point has a strainer 2
The groundwater flowing into the electrodes 14 and 15 is filtered, and flows into the riser pipe 16 through the well points.

The riser tube 16 has a pair of electrodes 14 and 15.
Each is arranged inside along the axial direction. One end of each riser tube 16 is disposed slightly above the bottom surfaces of the electrodes 14 and 15, and the other end of each riser tube 16 passes through the seal member 22 and is located above the ground. .

The other end of each riser pipe 16 is connected to a vacuum pump 17 through a swing hose 24 and a header pipe 25.
And each vacuum pump 17 is connected to a water storage tank 18.
Connected to each other.

As a result, when the vacuum pump 17 is driven, the spherical valve at the well point (not shown) is sucked up by the vacuum pressure.
The groundwater collected therein flows into the riser pipe 16 from a suction hole at a well point (not shown), is pumped up through the riser pipe 16, and is stored in a water storage tank 18.
As a result, the groundwater in the ground 19 is dehydrated.

The initial state of the polarity switching device 13 of the electroosmotic dehydration device 10 is “OFF” and the ground 1
An example of the electroosmotic dehydration method in the case where the charged state of the soil particle surface is negative in No. 9 is described below.

When the electroosmotic dewatering device 10 is operated, an alternating current flows from the power supply 11, and this alternating current is converted into a direct current by the rectifier 12 and flows to the polarity switching device 13. Then, since the polarity switching device 13 is in the “OFF” state, the electrode 15 indicates the polarity of the anode and the electrode 14 indicates the polarity of the cathode,
Direct current flows from the electrode 15 to the electrode 14. The gradient of the DC voltage applied between the electrodes 14 and 15 was set to a relatively high voltage, specifically, 5 V / cm.

At this time, since the charged state of the soil particle surface of the ground 19 is negative, the electrode 1
A water flow in the direction from 5 to the electrode 14 is generated (see the solid arrow in FIG. 1). As a result, the groundwater existing around the electrode 15 moves around the electrode 14. That is, the electrode 1
4 is the electrode on the water collecting side, and the electrode 15 is the electrode on the non-water collecting side. The moved groundwater flows into the electrode 14 through the slit 20 of the electrode 14 and is stored in the electrode 14.

The groundwater contained in the electrode 14 flows into the riser pipe 16 from a suction hole at a well point (not shown) by the vacuum pressure of the vacuum pump 17 and is pumped to the ground through the riser pipe 16. And
The groundwater is sent to the water storage tank 18 via the swing hose 24, the header pipe 25, and the vacuum pump 17. Thereby, the groundwater in the electrode 14 is drained.

As described above, the groundwater is collected on the electrode 14 and drained, and dewatering from the ground 19 is performed. The dewatering rate of groundwater at this time increases with a substantially constant gradient,
It reaches a maximum and then gradually decreases. Then, the polarity switching device 13 is switched to the “ON” state when the dehydration speed becomes 70% of the maximum dehydration speed. Then, rectifier 1
2 and the connection state between the electrodes 14 and 15 is switched, the polarity of the electrode 14 is changed from the cathode to the anode, and the polarity of the electrode 15 is changed from the anode to the cathode. Become. In the present embodiment, the dehydration rate was reduced to 70% of the maximum dehydration rate 72 hours after the power supply to the electrodes 14 and 15 was started.

By changing the polarity of the pair of electrodes 14 and 15, the direction of the water flow due to electroosmosis is opposite to the direction before the polarity switching device 13 is turned on, that is, from the electrode 14 to the electrode 15. Direction (see the dashed arrow in FIG. 1)
Becomes As a result, the groundwater existing around the electrode 14 moves around the electrode 15 and flows into the inside of the electrode 15 through the slit 20 of the electrode 15. Then, the inflowing groundwater is pumped up through the riser pipe 16 by the vacuum pump 17 and stored in the water storage tank 18.

The dehydration rate from the electrode 15 increases again due to the polarity conversion, and gradually decreases after a certain period of time. In this way, the groundwater is dehydrated from the electrode 15 and when 240 hours have passed since the start of energization between the pair of electrodes 14 and 15, the energization was stopped and the ground 1
End the dehydration from 9.

According to the electroosmotic dewatering method for the ground, the water content of the ground 19 after the dewatering is reduced on average in comparison with the water content before the dewatering, as shown in FIG. Accordingly, the strength of the ground 19 after the dewatering is almost uniformly improved as shown in FIG. 5 than the strength of the ground 19 before the dewatering. [Experimental Examples] Experimental examples supporting the effect of the above-described electroosmotic dewatering method for ground according to the present embodiment will be described below. 1. In this experimental example, a dehydration experiment was performed in an experimental soil tank using a loam having a high water content, and the relationship between the voltage between the electrodes, the dehydration rate, the water content reduction state, and the like and the electrical conditions were grasped. The effect of the electroosmotic dewatering method for the ground according to the present invention was confirmed, and conditions for properly using the method were determined. 2. Experimental Apparatus The experimental apparatus used in this experimental example will be described with reference to the apparatus schematic diagram of FIG. As shown in FIG. 6, width B = 200 m
In an experimental earthen tub 30 having a length of L = 400 mm and a height of H = 300 mm, a loam 31 is placed up to a height of 250 mm. The loam 31 has a depth of about 100 mm and a diameter of about 30 mm.
2 mm holes are provided at intervals of 200 mm, and a cylindrical member made of carbon having an outer diameter φ ₀ = 30 mm and an inner diameter φ ₁ = 9 mm is inserted into each hole as a pair of electrodes 32a and 32b. I have. On the outer peripheral wall of each electrode 32a, 32b,
An inflow hole (not shown) for allowing water contained in the loam 31 to flow into each of the electrodes 32a and 32b is formed.
Water flowing into each of the electrodes 32a and 32b through the inflow holes is sucked up by a vacuum device (not shown), and is dehydrated from the loam 31. A power supply device 33 is connected to each of the electrodes 32a and 32b via a conductive wire.
Direct current is applied between the electrodes 32a and 32b.

The data of ROHM 31 used in this experiment are as follows. - water content w = about 100% R50: Gravel min (2 mm) 14% sand fraction 19%, silt 43%, clay content (5 [mu] m or less) 24% - consistency (緊硬degree): liquid limit W _L = 12
1.6%, plastic limit W _P = 72% ph = 7.3 to 5.6 Experimental Method Experiment 1: A direct current was applied between the electrodes 32a and 32b for 10 days (240 hours), and the outflow of dewatered water from the loam 31 was measured. When the voltage gradient (constant voltage) between the electrodes 32a and 32b during energization is 0.5,
V / cm (= 10 V) (Experiment 1-1), 1 V / c
m (= 20 V) (Experiment 1-2), 2 V / cm (=
40V) (Experiments 1-3). Experiment 2: The voltage gradient between both electrodes 32a and 32b was set to 1 V / cm, and a direct current was applied between both electrodes 32a and 32b for 9 days (216 hours).
The outflow of dehydrated water from 1 was measured. However, the polarity of each electrode 32a, 32b is changed 24 hours after the start of the experiment, and each electrode 32a, 32b, 96 hours after the start of the experiment.
The polarity of 32b was converted again. At the start of the experiment, the experiment was performed with the electrode 32a set as the anode and the electrode 32b set as the cathode. Experiment 3: A voltage gradient between the two electrodes 32a and 32b was set to 5 V / cm, and a direct current was applied between the two electrodes 32a and 32b for 72 hours. Subsequently, the voltage gradient is reset to 1 V / cm, and the current is supplied for 168 hours. Thus, a total of 240
The energization was performed for a time, and the outflow of water dehydrated from the loam 31 was measured. However, the polarity of the electrodes 32a and 32b was changed when about seven hours had elapsed from the start of energization. 4. Experimental Results Experimental results of Experiments 1 to 3 described above will be described with reference to FIGS. 7 and 8.

FIG. 7 is a graph showing the change over time of the outflow amount of water due to the difference in electric conditions, and shows the experimental results of Experiments 1 to 3, respectively. According to FIG. 7, the amount of water flowing out at the end of the experiment was 1350 ml
In Experiments 1-3, the volume was about 1220 ml, in Experiment 2, 1000 ml, in Experiment 1-2, 620 ml, and in Experiment 1-1, 600 ml.

According to the results of Experiment 3 shown in FIG. 7, the larger the voltage gradient (constant voltage) applied between the pair of electrodes 32a and 32b, the larger the amount of water flowing out (the more water is dehydrated). I can do that).

From the gradient (= dehydration rate) of each graph showing the results of Experiment 1, the dehydration rate increased from the start of the experiment until the lapse of 60 to 80 hours from the start of the experiment, and became the maximum. Has a characteristic that the gradient gradually relaxes (the dehydration rate gradually decreases), and it was found that dehydration was performed continuously from the start of the experiment to the end of the experiment.

From the comparison between the results of Experiments 1-2 and 2 that the polarities of the pair of electrodes 32a and 32b are changed, the polarities of the pair of electrodes 32a and 32b are shorter than when the polarities of the pair of electrodes 32a and 32b are not changed. It was found that a large amount of water could be dehydrated in a long time. Also, from the results of Experiment 2, the electrodes 32a,
It was also found that the conversion of the polarity of 32b again increased the dehydration rate, which had tended to decrease.

FIG. 8 is a diagram showing the distribution of the water content in the experimental earthen tub 30 after the end of the experiment. And FIG.
(A) shows the results of Experiments 1-2, and FIG.
(B) shows the result of Experiment 2.

According to FIG. 8A, the water in the loam 31 is dehydrated from the electrode 32a (anode), and the average water content w1 around the electrode 32a is 89.78% (86.0%, 92.6%).
%, 92.2%, 88.3%). In contrast,
The water content around the electrode 32b is lower than that around the electrode 32a, and the average water content w2 is 78.08% (77.
4%, 79.9%, 79.4%, 75.6%). The difference (w1-w2) in the average water content is 11.7%.
Met.

On the other hand, according to FIG. 8B, the water in the loam 31 is dehydrated from both the electrodes 32a and 32b,
The average water content w1 around 2a is 82.08% (81.7).
%, 82.8%, 82.8%, 81.0%).
On the other hand, the water content around the electrode 32b is slightly lower than that around the electrode 32a, and the average water content w2 is 7%.
7.78% (80.4%, 79.6%, 78.0%, 7
3.1%). And the difference in average water content (w ₁ −
w ₂ ) was 4.30%.

From the experimental results shown in FIGS. 8A and 8B, it can be seen that the method of Experiment 2 reduces the water content by averaging as compared with the method of Experiment 1-2. Experiment 2
Average water content (w1 + w2 / 2 = 79.93)
%) Is the average water content (w1 + w) in the results of Experiments 1-2.
2/2 = 83.93%), which indicates that the method of Experiment 2 can dehydrate more water.

As described above, according to the method of Experiment 2, that is, the method of electro-osmotic dewatering of the ground according to the present invention, the water content ratio is reduced by averaging and shorter than the conventional method of electro-osmotic dewatering of the ground. It turns out that a lot of water can be dehydrated in time. 5. Conclusion From the above experimental results, conditions for properly using the electroosmotic dewatering method for ground according to the present invention are as follows. (1) The higher the voltage gradient applied between the electrodes 32a and 32b, the greater the amount of water flowing out.
It is desirable that the voltage gradient applied between them is as high as possible. (2) The change with time (dehydration rate) of the outflow of water is large during several tens of hours from the start of energization, and then tends to gradually decrease thereafter. When starting, it is desirable to change the polarity of the electrodes 32a, 32b. (3) According to (1) and (2), when the energization is started, a DC voltage as high as possible is applied to the electrodes 32a and 32b, and the polarity of the electrodes 32a and 32b is changed at a time when the dehydration rate is reduced. A large amount of water can be dehydrated in a short time and ROHM 3
It is possible to reduce the water content ratio of 1 substantially by averaging.

According to the electroosmotic dewatering method for the ground according to the present embodiment, the polarity of the pair of electrodes 14 and 15 is changed to reverse the direction of the water flow due to the electroosmosis, thereby obtaining the ground 1.
The water content ratio in 9 decreases uniformly without being biased around the electrode 14 or around the electrode 15.

Further, since the pair of electrodes 14 and 15 are directly cast on the ground 19 of the cohesive soil without being cast on the sand pile as in the prior art, the electrodes 14 and 15 are disposed above the groundwater level of the sand pile as in the conventional technique. There is no danger that the located part is dried and the function of the electrode is reduced.

As described above, the groundwater level (water content) of the ground 19 between the pair of electrodes 14 and 15 can be reduced on average by the electroosmotic dehydration method of the ground,
Accordingly, the average ground strength can be improved.
Further, the water content ratio of the soil material can be reduced. In addition, a relatively high voltage direct current is applied between the pair of electrodes 14 and 15, and the polarities of the electrodes 14 and 15 are reversed when the dehydration rate of the electrodes 14 decreases.
More groundwater can be dewatered from the ground 19 in a shorter time than in the past.

As shown in FIG. 3, the electroosmotic dewatering apparatus 10 according to the present embodiment has a pair of electrodes 14 and 1.
5, a submersible pump 26 may be arranged at one or both bottoms, and the riser pipe 16 may be connected to the submersible pump 26. If the submersible pump 26 can sufficiently drain the groundwater collected inside the electrode 14 or the electrode 15, the vacuum pump 17
, The groundwater pumped by the submersible pump 26 may be sent to the water storage tank 18 via the swing hose 24 and the header pipe 25. When the polarities of the electrodes 14 and 15 are converted by the polarity converter 13,
The current supply to the electrodes 14 and 15 may be stopped once.

[0062]

As described above, according to the method for electroosmotic dehydration of the ground according to the present invention, the groundwater level (water content) of the ground is obtained by changing the polarity of the pair of electrodes.
Can be reduced on average and the strength of the ground can be improved on average. Further, since the electrode is cast in a state where the outer peripheral surface of the electrode is in close contact with the ground, it is possible to prevent the function of the electrode from deteriorating.

Further, by applying as high a voltage as possible when applying a direct current between the pair of electrodes, it is possible to dehydrate a large amount of groundwater in the ground. In addition, by changing the polarity of the pair of electrodes at a time when the dehydration rate decreases after the start of energization, a large amount of groundwater can be dehydrated from the ground in a shorter time than in the past.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a partially crushed apparatus used in an electroosmotic dewatering method for ground in one embodiment of the present invention.

FIG. 2 is a perspective view showing an electrode in the electroosmotic dewatering device for ground shown in FIG. 1;

FIG. 3 is an explanatory view showing a part of an electroosmotic dewatering device for ground in another embodiment.

FIG. 4 is a diagram showing a comparison between the water content ratio before ground dewatering and the water content ratio after ground dewatering by the electroosmotic dewatering method for ground in the present embodiment.

FIG. 5 is a diagram comparing the ground strength before ground dewatering and the ground strength after ground dewatering by the electroosmotic dewatering method for ground in the present embodiment.

FIG. 6 is an explanatory diagram of an experimental apparatus used in an experimental example.

FIG. 7 is a graph showing experimental results of an experimental example.

FIG. 8 is an explanatory diagram showing an experimental result of an experimental example.

FIG. 9 is an explanatory view showing a conventional ground electroosmotic dewatering apparatus with a part thereof crushed.

FIG. 10 is a diagram showing a comparison between a water content ratio before ground dewatering by a conventional electroosmotic dewatering device and a water content ratio after ground dewatering.

FIG. 11 is a diagram showing a comparison between a ground strength before ground dewatering by a conventional ground electroosmotic dewatering device and a ground strength after ground dewatering.

[Explanation of symbols]

 Reference Signs List 10 ground electroosmotic dewatering device 13 polarity switching device 14 electrode 15 electrode 17 vacuum pump 18 water storage tank 19 ground 20 slit (hole for inflow of groundwater) 26 submersible pump

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinori Yamamoto 2-10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Corporation

Claims (2)

[Claims] 1. A method of electroosmotic dewatering of a ground in which a direct current is applied between a pair of electrodes provided at a predetermined interval in the ground to move groundwater in the ground to a collecting-side electrode and drain the groundwater. In the above, the pair of electrodes, constituted by a cylindrical body having a hole for inflow of groundwater on the outer peripheral surface, the outer peripheral surface of the cylindrical body is cast in a state of closely contacting the ground, between the pair of electrodes Applying a direct current to move the groundwater to the collecting-side electrode, draining the groundwater collected inside the collecting-side electrode, and starting the direct current supply between the pair of electrodes. The polarity of the pair of electrodes is converted at a time when the dehydration rate is reduced, and a direct current is applied between the pair of electrodes whose polarity has been converted, and the groundwater level of the ground between the pair of electrodes is reduced on average. And a method for electroosmotic dehydration of ground. 2. When a direct current is applied between said pair of electrodes,
The method for electroosmotic dewatering of ground according to claim 1, wherein a DC voltage as high as possible is supplied.