JPH0814102B2 - Liquefaction prevention method for soft sand ground - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing liquefaction of soft sand ground.

[0002]

2. Description of the Related Art Generally, the liquefaction phenomenon in soft sand ground is a phenomenon in which particles are disengaged from each other and float in the pore water. It is known that the ground is likely to be generated when subjected to repeated shearing forces such as earthquakes.

As measures for preventing liquefaction in this soft sand ground, there are measures for preventing the occurrence of liquefaction and measures for assuming the occurrence of liquefaction. The former one is a replacement method, a stabilization treatment method, There are various methods such as compaction method, gravel drain method, groundwater level lowering method, embankment method, etc.
The latter includes sheet pile construction, pile foundation construction, and solid foundation construction.

[0004]

However, the replacement method, the embankment method, and the stabilization method, which are measures for preventing the occurrence of liquefaction, require a long time and are economically expensive.
In addition, the compaction method has a large effect on noise and vibration and cannot be used as a foundation for existing structures, and the gravel drain method has the problem that the ground around the pile will sink after liquefaction, and the groundwater level will drop. There was a problem that the construction method had a large effect on the surrounding ground. On the other hand, the pile foundation method has a problem of maintaining the horizontal resistance, and the solid foundation method is effective only for light structures, and each of the above methods has its own problems.

The present invention has been made in view of the above problems, and an object thereof is to improve a soft sand ground uniformly and economically, and to eliminate noise and vibration.
It is to provide a method for preventing liquefaction of soft sand ground that can be applied to the foundation of existing structures.

[0006]

In order to achieve the above object, the first invention in the method for preventing liquefaction of soft sand ground of the present invention is a container for an anode and a cathode capable of transmitting water into the soft sand ground. Are embedded at appropriate intervals, a fine-grained substance containing a positively charged clay mineral is placed in the container of the positive electrode, and a direct current is passed between these two electrodes to give the positively charged viscous substance.
A fine particle substance containing a soil mineral is migrated to the container side of the cathode to adhere to the soil particles,

A second aspect of the present invention is that a container of water-permeable anode and cathode is buried at an appropriate interval in a soft sand ground, and the cathode container is a fine-grained substance containing a negative clay mineral. By applying a direct current between the two electrodes , the fine particle substance containing the negative clay mineral is migrated to the container side of the anode and adhered to the soil particles. Is to

A third aspect of the present invention is to embed a water-permeable container for an anode and a cathode in a soft sand ground at appropriate intervals, and a fine-grained material containing positive clay minerals in the container for the anode. br />, and the cathode container with fine particles containing negative clay minerals.
A granular material is put into each of the electrodes, and a direct current is passed between the two electrodes , so that the fine granular material containing the positively charged clay mineral is fed to the cathode container side, and the finely granular material containing the negatively charged clay mineral is added.
The composition is characterized in that the granular materials are respectively migrated to the container side of the anode and adhered to the soil particles,

A fourth aspect of the present invention is to embed a container for an anode and a cathode in a soft sand ground at appropriate intervals , and fine particles containing a positive clay mineral in the sand ground around the anode container .
By filling a substance and applying a direct current between these two electrodes , a fine particle substance containing the positively charged clay mineral is migrated to the container side of the cathode and adhered to the soil particles. Is to

A fifth aspect of the present invention is to embed an anode and a cathode container in a soft sand ground at appropriate intervals , and fine particles containing a negative clay mineral in the sand ground around the cathode container .
By filling a substance and passing a direct current between these two electrodes , a fine particle substance containing the negatively charged clay mineral is migrated to the container side of the anode and adhered to the soil particles. Is to

A sixth aspect of the present invention is to embed a container for an anode and a cathode in a soft sand ground at appropriate intervals , and fine particles containing a positive clay mineral in the sand ground around the anode container .
Material and negative in the sand ground around the cathode container
By filling each with a fine-grained substance containing clay minerals and applying a direct current between these two electrodes, the positively charged sticky substance
Fine particles containing soil minerals are migrated to the cathode container side, and negative particles containing clay minerals are migrated to the anode container side to adhere to the soil particles. It is to be.

[0012]

Thus, according to the above configuration, the soft sand ground
Placed in a buried permeable anode and cathode container
Positive or negativeFine-grained material containing clay mineralsBut some
Is filled in the sand ground around the anode container or cathode container.
Was positive or negativeFine-grained material containing clay minerals
However, due to the direct current flowing between these two electrodes,
Soil particles by migration to the container side or the container side of the cathode, respectively
Since it adheres to the child and adheres between the soil particles, the viscosity of the sand ground
It is possible to increase resistance or consolidation strength.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for preventing liquefaction of soft sand ground according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first invention in a method for preventing liquefaction of soft sand ground according to the present invention.

For liquefaction in the soft sand ground M, the resistivity FL against liquefaction is calculated by FL = R / L (where R is the dynamic shear strength ratio, and L is the shear stress ratio during earthquake). When the value of this resistivity is 1.0 or more, it is determined that the ground is not liquefied, and when it is 1.0 or less, the ground is liquefied.

In the present embodiment, as shown in FIG. 1, the average particle size (D50) of soil is 0.6 mm≤D50≤2.
A water-permeable anode container 1 and a cathode container 2 are horizontally and alternately arranged in a multi-step manner at intervals of 0.5 to 2.0 m in a liquefied ground M having a resistance FL of 0.806. Buried.

The anode container 1 is filled with a sticky fine-grained substance 3 containing a positively charged clay mineral, and the space between the anode container 1 and the cathode container 2 is 0.1 to 10. 5
When a direct current of V / cm is kept flowing for about 5 to 6 hours to 5 to 6 days, the positive clay mineral in the anode container 1
The sticky fine-grained substance 3 containing the particles migrates to the container 2 side of the cathode, adheres to the soil particles and adheres between the sand particles,
The viscous resistance of the sand ground is increased to uniformly improve the soft sand ground M.

The anode container 1 and the cathode container 2 are formed of a conductive metal, carbon fiber or the like in a cylindrical shape, and have a large number of small holes 1a, 2a through which water can pass.

As described above, as a result of electrophoresing the fine particles 3 containing the positive clay mineral in the liquefied ground M having the liquefaction resistivity FL value of 0.806, the following results were obtained. As shown in Table 1 of Table 1, the average particle size (R2) of soil is increased and the liquefaction resistivity FL value is 0.806 to 1.9.
Since it is 17, it is possible to prevent liquefaction of the sand ground,
Therefore, the effect of the present invention could be confirmed.

[0019]

[Table 1]

In Table 1 above, FL is the liquefaction resistivity, R is the dynamic shear strength ratio, L is the earthquake shear stress ratio, and R1 is a function of the N value and the effective loading pressure σ'v. The first term of the dynamic shear strength ratio R represented is R2, the second term of the dynamic shear strength ratio R represented by the function of the average particle diameter D50, and the third R3 is the function of the fine particle content ratio FC. The third term of the dynamic shear strength ratio R, r
d is the reduction factor of the shear stress ratio during an earthquake in the depth direction, ks is the design horizontal seismic intensity on the ground surface used for liquefaction determination, σv is the total loading pressure, σ′v is the effective loading pressure, and N is the standard penetration test. The N value, D50, obtained from the above, is the average particle size of soil.

The fourth aspect of the present invention is the same as the first aspect of the present invention.
And sticky fine-grained substance 3 containing positive clay minerals
The same results as in Table 1 can be obtained by filling the same with the above and subjecting these to electrophoresis on the cathode container 2 side (FIG. 4).

The second and fifth inventions of the present invention are also the cathode container 2 in the ground M similar to the first invention.
Alternatively, the same result as in Table 1 is obtained by filling the vicinity of the cathode container 2 with the sticky fine-grained substance 3 containing a negative clay mineral and subjecting these to electrophoresis on the anode container 1 side. It is possible (FIGS. 2 and 5).

Furthermore, the third and sixth inventions of the present invention are also the same as the above-described first invention, in the ground M, the container 1 of the anode or the periphery of the container 1 of the anode contains tacky clay containing positive clay minerals. The fine particle substance 3 of No. 3 and the viscous fine particle substance 3 containing the clay mineral having a negative polarity are filled in the container 2 of the cathode or the periphery of the container 2 of the cathode, respectively. The same results as in Table 1 can be obtained by subjecting the negative-electrode container 2 side to electrophoresis and the negatively-charged fine-grained substance 3 to the anode container 1 side, respectively (FIGS. 3 and 6).

Then, according to the present invention, positive or negative
As a fine-grained substance containing clay clay minerals,
Clay particles composed of soil minerals are used. As a clay mineral
Is montmorillonite, kaolinite, illite, etc.
Among them, montmorillonite is preferred among these
As a commercially available product, montmorillonite is
Bentonite as the main component can be used. Well
Also, clay forms a colloidal solution together with an aqueous solution.
However, it is more or less charged. This charging is the same type
In other words, it is based on the valence of the fracture part,
I have a load. Further, in the present invention, the anode container 1 and the cathode container 2 are not limited to horizontal as described above,
It can also be embedded vertically as shown in FIG.

[0025]

As described above, according to the present invention, the soft sand ground can be uniformly and economically improved without generating noise and vibration, and the structure of the existing structure can be used as a foundation of the existing structure. Can also be applied.

[Brief description of drawings]

[Figure 1] Anode container containing fine clay minerals
It is sectional drawing which put the granular material .

[Fig. 2] A cathode container containing fine clay minerals with negative polarity.
It is sectional drawing which put the granular material .

[Fig. 3] Anode container contains fine particles containing positive clay minerals.
Granules and negative clay minerals in the cathode container.
FIG. 4 is a cross-sectional view in which each of the fine particle substances is put.

[Fig. 4] Includes positive clay minerals around the anode container
FIG. 3 is a cross-sectional view in which a fine particle substance is filled.

[Fig. 5] Including negative clay mineral around the cathode container
FIG. 3 is a cross-sectional view in which a fine particle substance is filled.

[Fig. 6] Includes positive clay minerals around the anode container
Fine grained material , negative clay around the cathode container
FIG. 3 is a cross-sectional view in which fine grain substances containing minerals are filled.

FIG. 7 is a plan view showing a state in which an anode container and a cathode container are vertically embedded.

[Explanation of symbols]

M Soft sand ground 1 Anode container 2 Cathode container 3 Fine-grained material containing clay minerals

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 64-52906 (JP, A) JP-A 51-150813 (JP, A)

Claims (6)

[Claims] 1. A container of water-permeable anode and cathode is buried in a soft sand ground at an appropriate interval, and a fine-grained substance containing a positive clay mineral is put in the container of the anode, and both electrodes are charged. By passing a direct current between them, the positive
A method for preventing liquefaction of soft sand ground, characterized in that fine-grained substances containing clay minerals are migrated to the cathode container side and adhered to soil particles. 2. A permeable anode and a cathode container are buried in a soft sand ground at an appropriate interval, and a fine particle substance containing a negative clay mineral is put in the cathode container, and both anodes By passing a direct current between them, the negative
A method for preventing liquefaction of soft sand ground, characterized in that fine-grained substances containing clay minerals are migrated to the container side of the anode and attached to soil particles. 3. A container for water-permeable anode and cathode is buried in a soft sand ground at an appropriate interval, and a fine-grained substance containing positive clay mineral is put in the container for anode and cathode container. Fine particles containing negative clay minerals were placed in the container, and a direct current was passed between these electrodes to move the fine particles containing positive clay mineral to the container side of the cathode. A method for preventing liquefaction of soft sand ground, characterized by migrating fine particles containing negative clay minerals to the container side of the anode and adhering them to soil particles. 4. A container for an anode and a cathode is buried at an appropriate interval in a soft sand ground, and the sand ground around the anode container is filled with a fine-grained substance containing a positive clay mineral. ,
Liquefaction of the soft sand ground characterized by causing a fine current substance containing the positively charged clay mineral to migrate to the container side of the cathode and adhere to the soil particles by applying a direct current between these two electrodes. Prevention method. 5. A container for an anode and a cathode is buried in a soft sand ground at appropriate intervals, and the sand ground around the cathode container is filled with a fine-grained substance containing a negative clay mineral. ,
Liquefaction of the soft sand ground characterized by causing a fine-grained substance containing the negative clay mineral to migrate to the container side of the anode and attach it to the soil particles by applying a direct current between these two electrodes. Prevention method. 6. A container for an anode and a cathode is buried at an appropriate interval in a soft sand ground, and a fine-grained substance containing a positive clay mineral is embedded in the sand ground around the anode container, Contains negative clay minerals in the sand ground around the cathode container
The positive clay clay mineral was included by filling each fine granular material and applying a direct current between these electrodes .
Fine-grained material to the cathode container side, and negatively charged clay mineral
A method for preventing liquefaction of soft sand ground, characterized in that fine-grained substances containing iron are migrated to the anode container side and adhered to soil particles.