JP2584421B2 - Forced water collection method applying electroosmosis phenomenon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention simply employs a sand pile in soft ground such as a sand drain method, a sand pile method, and a sand compaction method, which are conventional methods for promoting consolidation of soft ground. Or by applying pressure or loading to the surface of the ground in addition to the sand pile, compressing and guiding the high moisture content in the soft ground in the direction of the sand pile, and collecting water near the sand pile. Unlike the construction method of using the capillary phenomenon to allow water to ooze into the surface of the sand pile to promote the compaction of soft ground, insert a slit pipe made of iron into these sand piles for the cathode, Also, in order to most rapidly increase the compaction between sand piles and sand piles, an iron bar that acts as an anode in soft ground intended for that purpose is inserted into the ground and installed. The cathode side of the slit tube is an iron bar in the ground As anode, and causing electroosmotic phenomenon during which the soil through a DC voltage,
This is a forced water collection method that forcibly performs rapid dewatering of the soft ground layer, thereby promoting the compaction of the soft water-rich layer most effectively in a short period of time.

(Prior art) Conventionally, it is necessary to strengthen the ground by promoting the consolidation of these soft layers by using various methods such as a sand drain method, a sand pile method, a sand compaction method, etc. as a processing method of these soft layers. Most of the soil is in landfills, reclaimed lands, wetlands, etc. around the estuary, and the ground is composed of extremely fine soil particles such as soft clay, silt, organic soil, and ultrafine sand.

Since the coefficient of permeability of the soil is k = 10 ^{−3 cm 2} / sec or less, it takes a long time until dewatering and consolidation are completed even in the above-mentioned conventional consolidation promoting method using various methods. The main cause is the ground composed of these viscous soils or ultrafine soils, so the water-containing state is absorbed water rather than pore water, and the absorbed water around the soil particles is It is a common belief in the field of geotechnical engineering that the formation of a target double layer makes it difficult to dewater it even under pressure. Even if a method such as vacuum is used, the upper limit of the dewatering is limited to the soil permeability coefficient k = 10 ^{−3 cm} / sec, and the depth is also limited. For this reason, dewatering in sand piles is mainly performed by using capillary phenomenon or vacuum method, but the main purpose is dehydration of adsorbed water in the soft layer composed of ultrafine soil particles between sand piles. Requires a very long time even if a sand mat or the like is loaded as a load on the surface of the ground, or if vacuum packing is performed. Conventionally, the well point was used as an electrode in a fine sand having a critical permeability coefficient of k = 10 ^{−3 cm} / sec, but in this case, a large potential difference was applied, so that the Most of the resulting current is exchanged for Joule heat and lost,
In addition, in the ground such as a landfill containing salt, the chlorine gas is generated only by the electrolysis, and the purpose of dehydration cannot be achieved.

(Problems to be Solved by the Invention) The present invention was conceived in order to solve these conventional disadvantages, and in various conventional methods for promoting consolidation,
Viscous soil with high water content and low permeability, silt,
It shortens the long working period required for consolidation of ultrafine sand and the like, and makes the dehydration effect remarkably effective.

(Means for Solving the Problems) In the present invention, the electroosmosis phenomenon is applied to a ground having a high water content in a very fine soft ground which requires dewatering and consolidation of the soft ground, that is, a low DC voltage, Connect the cathode side to the iron pipe with slit holes in the sand pile and the anode side to the iron rod between the sand piles, and apply the voltage below the voltage to the ground that requires consolidation between them. The electro-osmosis phenomenon is used to collect water and pore water from fine soil particles in the ground from the anode side to the cathode direction.

According to the method of the present invention, dehydration can be easily performed without the need for a conventional load on the ground surface or a vacuum packing method. In addition, the soil water collected in the iron slit hole electrode tube in the sand pile can be easily drained by a pump or a vacuum method.

(Embodiment) The configuration of the present invention will be described in detail with reference to the embodiment shown in FIGS.

Reference numeral 1 denotes a sand pile of a sand drain method, a sand pile method, or the like. An electrode tube 2 having an iron slit hole is inserted into the existing sand pile as a cathode. This slit electrode tube has an inner diameter of about 75 mm, and has a width of 6 mm to 8 mm and a length of 15 cm to 20 cm around the slit electrode tube 2 as shown in FIG.
The slit holes of FIG. 4 penetrate in four rows at a certain angle as shown in FIG. This iron tube 2 with slit holes
Into the sand pile 1 such as the existing sand drain or sand pile method. The depth of these iron cathode slit tubes 2 is set so as to reach a depth suitable for the soil layer requiring the most consolidation.

Further, an iron rod 3 having a diameter of about 25 mm is penetrated into the ground 4 in the middle of the planar arrangement of the electrode tube 2 with slit holes for the cathode, and these are used as the anode side. That is, after the installation of the electrode tube 2 with the slit hole for the cathode and the iron bar 3 for the anode, the electric wires are connected to the electric wire connection portions 8 and 9 on the ground portion, and
Is connected to a cathode, and 3 is connected to an anode, and direct current is supplied.

As a result, as shown in FIG. 2, the row of the electrode tubes 2 with slit holes in the sand pile is connected in parallel with the negative side of the DC current, and the group of iron rods 3 is connected with the positive side DC current in parallel.

In this case, the potential gradient of the DC voltage differs depending on the value of the hydraulic conductivity and the water content of the soil of the ground 4 requiring consolidation, but from the results of the implementation, the most appropriate voltage is cast on the ground 4. The most effective value was 025 v / cm to 050 v / cm per unit distance with respect to the distance between the iron bar 3 acting as the anode and the electrode tube 2 with a steel slit hole for a cathode installed in a sand pile. That is, a very low voltage is used.

As described above, an electroosmosis phenomenon occurs between the iron rod group on the plus side and the electrode tube 2 with the iron slit hole on the minus side, and pore water and adsorbed water existing in the ground 4 are reduced to the minus side, that is, sand. Water is collected on the circumference of the electrode tube 2 with a slit hole made of iron in a pile. Soil water collected in the electrode tube 2 with a slit hole on the minus side is easily drained on the ground by a pump or a vacuum method. The drainage lowers the water head in the iron-slit electrode tube 2 by this drainage, so that the action by the electroosmosis phenomenon is further facilitated and the water content of the ground 4 is rapidly reduced.

(Effects of the Invention) The present invention is based on the value of the hydraulic conductivity of soil before the soil 4 requiring dewatering and consolidation, and the strength of the voltage to be applied depending on the value of the soil test result in which the value of the water content is measured in advance. The purpose of this technique is to determine the potential gradient and to apply the electroosmosis phenomenon to the soil between the poles. Accordingly, it is superior to the various sand pile methods and consolidation methods in the following points.

1) The installation of the iron bar 3 as the positive electrode and the electrode tube 2 with slit holes in the sand pile on the negative side is extremely simple.

2) The operation is simple because a very low DC voltage is used.

3) Since the electroosmosis phenomenon is used, dewatering and water collection work extremely efficiently even on the ground 4 constituted by extremely fine soil particles.

4) Dehydration and water collection are extremely efficient, so that the construction period can be significantly reduced.

5) In order to confirm the present invention, experiments were conducted under various soil conditions and water content conditions. As a result, as shown in FIG. 6, it was found that the water content was extremely remarkably reduced in a short period. That is, it became clear that the progress of consolidation was achieved in a short time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectional front view showing an embodiment of the present invention, FIG. 2 is a case where the present invention is applied to an equilateral triangular arrangement of a sand pile method, and FIG. 3 is used as a cathode in the present invention. Enlarged front view of an electrode tube with an iron slit hole, FIG. 4 is a cross-sectional view taken along the line A-A 'of FIG. 3, FIG. 5 is an enlarged front view of an iron bar for an anode, and FIG. It is a table. DESCRIPTION OF SYMBOLS 1 ... Sand pile 2 ... Electrode tube with slit hole for cathode 3 ... Iron bar for anode 4 ... In the soil 5 ... Cathode side electric wire 6 ... Anode side electric wire 7 ... Slit hole 8 ... Metal fittings 9 ... Drainage fitting connection

Claims (1)

(57) [Claims] 1. An iron tube provided with a slit hole in a sand pile is driven as a cathode, and an iron bar is driven as an anode between the sand piles. More DC voltage is applied to give a potential gradient between the anode side and the cathode side, and the water content in the soft ground, which is fine-grained soil between each sand pile, is introduced into the iron slit electrode tube in the sand pile on the cathode side. Forced water collection method for the purpose of dewatering soft ground using electroosmosis phenomenon to collect water.