JP2007303270A - Ground improvement construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the strength of the ground by uniformly, homogeneously and vacuously permeating into the ground, by a combination of a soil improvement technology of a construction field or a construction method for supplying a grout material such as cement milk and a foaming material. <P>SOLUTION: This ground improvement construction method is composed of a process of extending a perforated pipe 3a for supplying fresh air or fresh water from the ground surface 1a of the ground 1 in polluted soil in the ground 1b to the inside of the ground, a process of putting the inside of the ground 1b in a substantially vacuum state by decompressing a peripheral area simultaneously when pumping underground water in the vicinity in the ground 1b by a super well point construction method for arranging two or more of wells 2 at a predetermined interval in the ground 1b, a process of repeating supply of the fresh air of the fresh water via the perforated pipe 3a of a grout material supply facility 3 extended in the ground 1b from the ground surface 1a, and a process of returning the underground water in the ground 1b up to a natural underground water level. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention is an improvement method of the ground in the soil improvement technology in the construction field, a method of covering the ground surface with an airtight material, a super well point method, and a grout material such as cement milk and foam from the ground The purpose of this is to improve the strength of the ground by uniformly and uniformly infiltrating into the ground by a combination with a construction method for supplying the ground.

In general, the safety and economic efficiency of underground work such as civil engineering, architectural foundation works, subways, and underground shopping streets are greatly affected by the quality of groundwater countermeasures.

Conventionally, as countermeasures for groundwater, there are known water-stopping works that prevent the inflow of groundwater with a shielding wall, or groundwater level lowering methods that lower the groundwater level by draining groundwater to the ground.

The inventors and applicants of the present application own the following patented invention.
Japanese Patent Laid-Open No. 2000-27170 (Patent No. 3243501) JP 2001-11846 (Patent No. 3280935)

The above-mentioned patented invention relates to a ground improvement method by lowering a groundwater level called a so-called superwell point method.
The outline of the superwell point method is as follows. That is, it is a construction method in which forced drainage is performed while keeping the inside of the well in a vacuum by making the strainer part into a double pipe structure (special separate screen).
Structure of special separate screen The separate screen has a double bridge structure consisting of an inner tube and a winding strainer. The groundwater flowing from the winding strainer is separated into air and water between the double pipes and flows into the well through the lower vent. Continuous vacuum drainage is made possible by applying a negative pressure to the inside of the double pipe by a vacuum pump.

This has the following effects. First, the vacuum effect is demonstrated at a large depth by the development of a special separate screen, and it can be propagated over a wide area and forcedly drained. Secondly, unlike a normal well point method which is limited to a depth of 6 to 7 m, forced drainage in a vacuum at a depth equivalent to that of a deep well is possible. Thirdly, since the well effect is improved by the vacuum effect for deep wells having poor well efficiency due to gravity drainage and requiring a large number, the number of constructions can be reduced. Fourth, when the water level is lowered to the screen position by the vacuum deep well construction method, it is possible to eliminate the fact that air enters the well and the vacuum effect is lowered. Fifth, this construction method enables forced drainage due to the vacuum effect at a deep depth, and the pumping volume is 1.2 to several tens of times larger than the conventional construction method, resulting in a rapid reduction of groundwater in a wider area. This is a deep vacuum drainage and consolidation dehydration method.

In the present invention, two or more wells are provided at a predetermined interval, and the ground improvement is further performed by carrying out the above-described superwell point method.

The first aspect of the present invention is a method of extending a perforated pipe for supplying a grout material from the ground surface to the ground in the ground improvement method, and an airtight sheet or a concrete material or When pumping groundwater in the vicinity of the ground by the process of laying an airtight material such as pavement with asphalt material or new sludge, and the super well point method with two or more wells in the ground at a predetermined interval Simultaneously reducing the pressure in the surrounding area of the ground to bring the ground into a substantially vacuum state, and supplying a grout material such as cement milk or foaming material through a perforated pipe extending from the ground surface to the ground; and It consists of the process of returning underground water to the natural groundwater level.

  The second aspect of the present invention is a method of extending a perforated pipe for supplying fresh air or fresh water into the ground from the ground surface of the contaminated soil in the ground improvement method, and a ground surface of the ground. Super well point construction method in which a single or two or more wells are provided at predetermined intervals in the ground, and a process of covering an airtight sheet or a pavement made of concrete or asphalt or a new sludge The process of pumping groundwater in the vicinity of the ground and depressurizing the surrounding area of the ground to make the ground almost vacuum, and the perforated piping of the grout material supply facility extending from the ground surface to the ground It consists of the process of repeating the supply of fresh air or fresh water through the process and the process of returning the underground water to the natural groundwater level.

According to the third aspect of the present invention, in the ground improvement method according to the first invention, the operation of the super well point method in which two or more wells are provided at a predetermined interval is stopped, or the operation of the super well point method is stopped. The airtight material laid on the ground surface is removed along with the stop, and air is supplied by natural air supply due to a difference in pressure between the ground and the ground.

According to a fourth aspect of the present invention, in the ground improvement method according to the first aspect, in the alternate layer ground of the viscous soil layer and the sand layer, the pore water pressure of the sand layer below the viscous soil layer is set at a predetermined interval between two or more wells. By applying a stress load to the viscous soil layer and depressurizing it, the viscous soil is consolidated and dehydrated by suctioning and depressurizing each other by a super well point method provided open.

According to the fifth aspect of the present invention, in the ground improvement method according to the first aspect of the present invention, in the alternate layer ground of the viscous soil layer and the sand layer, two or more wells are provided at predetermined intervals in the sand layer below the viscous soil layer. By sucking and depressurizing each other by the Superwell Point method, a vacuum is created to evaporate and dehydrate the moisture in the viscous soil layer.

A sixth aspect of the present invention is the ground improvement method according to the first aspect, wherein two or more wells are provided at predetermined intervals in the sand layer below the viscous soil layer in the alternating soil layer of the viscous soil layer and the sand layer. The existing structure foundation and the lower layer ground of the ground structure installed on the unevenly subsurface surface are drilled with a curved boring machine by sucking each other by the super well point method and reducing the pressure. By installing the perforated pipe in the lateral direction in a form that passes between the left and right sides, the grout material is injected from the perforated pipe into the ground to improve the ground, and the unevenly subsidized structure It is designed to lift up.

According to a seventh aspect of the present invention, in the ground improvement method according to the first invention, the sand layer is sucked into the ground by a super well point method in which two or more wells are provided at predetermined intervals. After reducing the water level in the ground by reducing the pressure, the dynamic consolidation method is performed.

The eighth aspect of the present invention is a ground improvement method according to the first aspect of the present invention, in the operation of a super well point method in which two or more wells are provided at predetermined intervals in the ground of a sand layer. Among the wells, a water-tightening action is generated in the ground by alternately repeating the relationship of giving a pumping action to one well and giving a suction action to the other well every predetermined time.

Since the present invention is configured as described above, the following effects can be obtained. In other words, various vacuum effects occur when pumping and compacting dewatering are performed at a large depth and a large degree of vacuum Pv≈−0.085 Mp. Using this effect, early consolidation dehydration is possible, and new ground improvement can be achieved by using the features in a complex manner.
In the first to fourth aspects, it can be expected that the water level is largely lowered by sucking each other by two or more superwell point methods due to the vacuum effect. Moreover, it can be loaded by increasing the stress load by lowering the lifting pressure of the lower part of the clay soil instead of the method of pressurizing with the embankment as a ground improvement of the clay soil. Furthermore, in claim 2, there is an effect that the soil contaminated by the uniform vacuum infiltration of fresh air or fresh water can be efficiently purified.

According to the fifth aspect of the present invention, the residual subsidence amount of the viscous soil can be subsidized even under the existing structure by sucking each other by the two or more superwell point methods.

According to the sixth aspect, the uneven settlement of the generated structure can be corrected by lifting it with a permanent grout material.

In claim 7, with a combination of two or more Superwell Point methods and dynamic consolidation methods, the water level can be lowered to a deep location, unsaturated ground can be created, and the propagation of impact can be extended to a deep location. Ground improvement became possible.

According to the eighth aspect of the present invention, the water grounding effect of the sand ground can be expected by the swing cleaning effect of the super well point method. In addition, the super well cleaning effect can strengthen the ground by removing clay and colloids from the loose sand ground.

The present invention is configured as described above, and the best mode for carrying out the invention is as follows.
As the best mode for carrying out the present invention, an airtight material is covered on the ground surface, and two wells with high pumping efficiency are excavated as a means for pumping groundwater, and the superwell point method is used. A case where a perforated pipe is buried between two wells will be described with reference to the drawings.

FIG. 1 is a flowchart showing a ground liquefaction prevention method according to this embodiment. In the same figure, in the soil improvement work of cohesive soil in the present embodiment, as a step (1): preparation work, the impermeable wall 5 is constructed so as to surround the target ground. Step (2): A plurality of wells (super well points) 2 are installed. Step (3): A supply facility 3 for grout material 9 such as cement milk or foam material is installed on the ground and in the ground. Step (4): Covering the airtight material 6 on the ground surface. Step (5): Ground water pumping and air bubbles are degassed by the super well point method installed in the step (2). Step (6): The grout material 9 is vacuum infiltrated into the underground 1b by being supplied through the perforated pipe 3a of the liquid supply equipment 3 such as cement milk or foamed material in the step (3). Then, the liquid material uniformly penetrates into the ground. Step (7): All or part of the airtight material 6 covered in the step (4) is removed. Step (8): The supply equipment installed in the step (3) is removed. Process (9): The groundwater in the ground is condensed to the natural water level. Step (10): The two wells installed in the step (2) are removed. Step (11): The impermeable wall 5 constructed in the step (1) is removed.

In the above embodiment, depending on the structure of the target ground, the structure existing on the ground, the state of the ground surface, etc., the steps (1) and (4) and the steps (7) and (11 corresponding to these, respectively. ) May be omitted. Hereinafter, each of the above steps will be described in detail, and then the state change in the ground will be described.

"Process (1): Construction of impermeable wall 5"
As shown in Fig. 2, first of all, the impervious wall 5 is covered with steel sheet piles to the required depth so as to surround the ground 1b of the alternate ground 1 consisting of the sand layers 1 ₁ and 1 ₃ and the cohesive soil layer 12 to be improved. Is constructed and constructed from the ground. At this time, it is assumed that the top height of the impermeable wall 5 is constructed so as to protrude from the ground surface 1a, and the water impermeability is secured between members such as steel sheet piles constituting the impermeable wall 5. .

"Process (2): Installation of well 2 (superwell point)"
Next, a plurality (two in the illustrated example) of wells 2 (super well points) are installed inside the impermeable wall 5 constructed in the above step (1).

Here, as shown in FIG. 8, the well 2 (super well point) includes a casing 2a, an airtight lid 2b, a strainer 2c, an earth and sand pit 2d, a pumping pump 2e, a vacuum pump 2g, pipes 2h and 2i, and a water tank 2j. This is a large-capacity, high-lift type pumping system that satisfies the functions of collecting water into well 2 and pumping out of well 2, which are the main components, with independent vacuum pump 2g and pump 2e. It has been proposed by a person (see Patent Document 1). Here, FIG. 8 shows a state in which the groundwater surface 1c is lowered, and arrows in the drawing indicate the flow directions of the groundwater and air. In addition, a state in which a negative pressure is propagated in the lower portion of the well 2 in FIG. In FIG. 2, the ground equipment shown in FIG. 8 is omitted.

"Process (3): Installation of grout material supply equipment 3"
Next, as shown in FIG. 2, the necessary number of perforated pipes 3a are installed inside the impermeable wall 5 constructed in the above step (1) using a drilling method such as a boring work, and vertically A pipe 3b and a valve 3c are installed at the upper end portion of the installed perforated pipe 3a to constitute a supply equipment 3 that functions as a grout material introduction path from the ground. Note that the valve 3c is closed at the installation stage of the supply equipment 3 for supplying grout material such as cement milk or foamed material. Here, the arrows indicate the flow direction of the grout material 9 from the ground surface 1a to the ground 1b.
The supply equipment 3 for supplying grout material 9 such as cement milk or foamed material in FIG. 3 includes two wells installed on the ground structure 8 installed on the existing foundation structure 7. Among them, from one well to the other well, use a drilling method such as curved boring from the ground surface 1a to the ground 1b, and a curved perforated hole through the underside of the existing structures 7 and 8 The pipe 3a is buried in the horizontal direction. The supply facility 3 also uses fresh air or fresh water to improve the contaminated soil so as to uniformly infiltrate the ground with vacuum.

“Process (4): Covering the airtight material 6”
Subsequently, an airtight material 6 is covered on the ground surface 1a of the underground 1b to be liquefaction-prevented surrounded by the water-impervious wall 5 constructed in the step (1), and an end portion of the airtight material Supplying the distribution route of the grout material 9 from the above-mentioned part (3) by processing so that the airtight material can be held in some openings generated by the perforated pipe 3a and the well 2 Restrict to one line of facility 3. The airtight material 6 may be an airtight sheet, a new sludge that does not emit bad odors, a pavement made of asphalt material or concrete material, or the like. The grout material 9 includes cement milk or foam material. For construction to improve contaminated soil, use fresh air or fresh water.

By going through the above steps (1) to (3), the target underground 1b is constructed in a region where the side and upper part are sealed in a certain range.

"Process (5): Groundwater pumping, air bubble deaeration"
Here, by utilizing the well 2 installed in (2) above using the super well point method, the groundwater existing in the ground 1b is collected in the well 2 and collected from the well 2 The groundwater is pumped to the ground and lowered to the required groundwater level. At this time, the state of the underground 1b is that the groundwater existing in the underground 1b in the region above the groundwater surface 1c is removed and the grout material 9 existing in the underground 1b is also excluded. However, although the soil particles constituting the underground 1b exist, a very high vacuum state (hereinafter referred to as “substantially vacuum”) is formed. In FIG. 8, the state of the fall of the groundwater surface 1c used as a natural groundwater level is shown.

"Process (6): Supply of grout material 9 such as cement milk or foam material"
Next, with the supply equipment 3 installed in the above step (3), the valve 3c is opened from the ground via the piping 3b, 3b and the perforated piping 3a through the grout material 9 such as cement milk or foaming material. Supply to underground 1b using the pressure difference. However, before proceeding to this step of supplying the grout material 9 to the underground 1b, the functions of pumping and draining the well 2 and degassing are stopped. Here, since the underground 1b is substantially in a vacuum state as described above, the underground 1b is uniformly filled at a very high diffusion rate. In addition, when supplying fresh air or fresh water to the grout material 9 instead of cement milk or foaming material, the above-described supply equipment 3 is used.

“Process (7): Removal of airtight material 6”
Next, the airtight material 6 covered in the step (4) is removed. At this time, since the atmospheric pressure in the vicinity of the ground surface 1a of the underground 1b is close to the atmospheric pressure by the step (3), there is no difference in the internal and external pressure between the underground 1b and the ground, and it can be easily removed.

“Process (8): Removal of grout supply equipment 3”
Subsequently, the grout material supply facility 3 is removed and the pipe pit is backfilled.

“Process (9): Condensate”
Here, the groundwater pumped up in the above step (5) is condensed using the well 2 to the groundwater surface 1c at the natural groundwater level. In this process, construction works with small head differences between the groundwater surface 1c after pumping the groundwater and the groundwater surface 1c in the natural state may proceed to the next step (10) without returning the groundwater taken from the well 2. What is necessary is just to determine by construction scale.

“Process (11): Removal of Well 2 (Super Well Point)”
Next, remove well 2 and refill the well.

“Process (12): Removal of impermeable wall 5”
Finally, the impermeable wall 5 is removed and the series of processes is completed. Here, when it is necessary to periodically repeat the improvement measures for the ground 1, without removing the perforated piping 3a, the well 2 and the impermeable wall 5 of the supply facility 3, it is left to reduce the man-hour for the next construction. You just have to.

Next, an embodiment in an environment different from the steps (1) to (10) will be described. However, the part which overlaps with the said process is abbreviate | omitted and only a changed part is demonstrated.

As shown in FIG. 3, when the ground surface 1a is covered with an airtight sheet or a new non-odorous sludge, concrete, or asphalt, the airtight material 6 is covered with a structure foundation in the underground 1b to be further improved. 7 and a case where a ground structure 8 such as a large oil tank or a lime tank is constructed, and further, examples of the case where the underground 1b to be improved is extensive will be explained together. .

In such an example, the steps (1), (4), (7), and (11) can be omitted, and in the step (1) for the reason of targeting a wide range of underground 1b. Without constructing the impermeable wall 5, it is possible to cope by lowering the groundwater surface 1c over the surrounding area of the target underground 1b, and the removal of the impermeable wall 5 described in the step (11) is unnecessary. It becomes. In addition, the ground surface 1a is provided with an airtight material 6, which can be used for the purpose and procurement of plastic sheets, waterproof tents, or pavement made of fresh sludge that does not emit bad odor, cement or asphalt, etc. It shall be used according to In addition, even when the airtight material 6 is not constructed, the ground structure is such that a highly airtight impermeable layer is widely formed in the upper layer of the underground 1b for the purpose of ground improvement. In this case, this impermeable layer can be an alternative material for the airtight material 6 (not shown).

However, since the existing structure foundation 7 and ground structure 8 exist at the position of the ground surface 1a of the ground 1b of the alternate layer base 1 composed of the sand layers 11 and 13 and the cohesive soil layer 12 to be improved, the step (3 ), Change the configuration of the supply equipment 3 and perform the boring of the lower ground of the structure foundation 7 instead of the perforated pipe 3a in the vertical arrangement as shown in FIG. By installing the perforated pipe 3a in the horizontal direction in the form, it becomes possible to supply the permanent grout 9 such as the effective foam material described in the step (6).

Other configurations are the same as those in the steps (2), (3), (5), (6), and (8) to (10).

From here on, by adopting the superwell point method as the groundwater pumping process of the present example, the explanation will be made more effectively, and the physical phenomenon occurring in the underground 1b, which is the target of ground improvement, will be clarified. This will be explained visually.

As shown in Fig. 4, in the steady state before the ground improvement work, the soil particles 4a, which are the main constituent materials of the underground 1b, the groundwater 4b in the form of free water, and the physicochemical (electrical) bonding strength There are adsorbed water 4c adsorbed on the soil particles 4a and air bubbles 4d interposed in the free water 4b, respectively.

Next, as shown in FIG. 5, in the above step (5), the state of the underground 1b after the pressure reducing action of the underground 1b and the pumping and draining of the groundwater 4b is the state of the groundwater 4b being the free water 4b. Therefore, since the water is collected in the well 2, only the soil particles 4a and the adsorbed water 4c exist. Here, the field pressure of the soil particles 4a and the adsorbed water 4c is almost in a vacuum 4e state. This improvement in the degree of vacuum makes a difference between the general well point method and the super well point method, and smoothly supplies the grout material 9 such as cement milk or foam to the underground 1b described in the following paragraphs. In addition, since the supply amount of the grout material can be maximized, it is a very effective means under conditions where the super well point method can be adopted.

Next, as shown in FIG. 6, in the previous step (6), the state in which the air is supplied from the ground surface 1a to the ground 1b is a region temporarily placed in the vacuum 4e state. It is filled with supplied air 4d '.

Next, as shown in FIG. 7, in the previous step (9), the groundwater 4b is condensed into the ground 1b and the groundwater surface 1c is restored to the groundwater level in the steady state. Since the free water 4b is submerged in the water, the amount of air intervening in the groundwater 4b increases, so that the air content of the groundwater 4b increases. As a result, since the degree of unsaturation of groundwater 4b, which is generally unsaturated, further progresses, the water ratio is relatively reduced to suppress the increase in the water pressure of pore water existing between the soil particles. The ground can be improved by avoiding the reduction of the frictional force.

FIG. 9 and FIG. 10 show a gate-shaped structure 8 such as a crane that supports a horizontal girder 8 ″ with two right and left columns 8 ′, and the foundation portion 7 ′ that supports the structure is unequal. The basic grout material 9 that allows foaming by the curved perforated pipe 3a shown in Fig. 3 after dehydration at an early stage by vacuum dehydration using two or more Superwell Point methods for subsidence. By pouring below the portion 7 ', the base portion can be lifted up so as to push it upward.

FIG. 11 shows a comparison of ground improvement work for loose sand ground. In other words, with the conventional dynamic consolidation method alone, the impact below the groundwater surface due to the dynamic consolidation method is weak and the increase in strength is small, so strength cannot be expected for clay soil or less. Therefore, in addition to the above-mentioned dynamic consolidation method, when two or more Superwell Point methods are used, the pressure due to the dynamic consolidation method is further reduced by reducing the groundwater level by vacuum dehydration and early consolidation dehydration. You can tell deep deep, cohesive soil layer 1 ₂ may be dehydrated in vacuum effect.

FIG. 12 shows a large amount of water (Q≈1 to 4.0 when two or more Superwell Point methods are used.
t / min) to the ground, and then vacuum suction is performed at a high degree of vacuum (Pv = -0.1 to 0.08MP). Water and suck in at the same time.
By removing the fine particles of the sand particles, the particle matrix is prepared and the strength of the sand ground is increased (see FIG. 13). Note that the decrease in strength of the sand ground is due to the inclusion of a large amount of colloid and silt in the sand. Moreover, the effect of watertightness can be expected by the swing effect.

It is a flowchart which shows the ground improvement construction method of embodiment which concerns on this invention. It is sectional drawing which shows the structure by the well, the cutoff wall, vertical perforated piping, and an airtight sheet | seat in the ground improvement method of embodiment which concerns on this invention. It is sectional drawing which shows the structure by the well, the ground structure, curved perforated piping, and pavement in the ground improvement method of embodiment which concerns on this invention. It is a fragmentary sectional view which shows the relationship with the soil particle in the steady state of the ground improvement construction method of embodiment which concerns on this invention, free water, adsorbed water, and an air bubble. It is a fragmentary sectional view which shows the relationship with the soil particle and adsorbed water in the ground water (free water) and air bubble exclusion state of the ground improvement construction method of embodiment which concerns on this invention. It is a fragmentary sectional view which shows the relationship with the soil particle in the air supply state of the ground improvement construction method of embodiment which concerns on this invention, adsorbed water, and air. It is a fragmentary sectional view which shows the relationship between the soil particle in the condensate state of the ground improvement construction method of embodiment which concerns on this invention, free water, adsorbed water, and an air bubble. It is sectional drawing which shows the well (super well point construction method) utilized in the process of pumping up ground water in the ground improvement construction method of embodiment which concerns on this invention, and the pressure reduction process in the ground. It is the schematic which shows the lift up construction in which a structure inject | pours a permanent grout material into the foundation | foundation part of a portal crane according to this invention. FIG. 10 is an enlarged cross-sectional view of a part of FIG. 9. It is explanatory drawing of the conventional construction method in sandy ground improvement. It is explanatory drawing of the sandy ground improvement construction method by this invention. It is a schematic explanatory drawing of the present invention which adopted a swing washing system. It is a schematic explanatory drawing of the present invention which adopted a swing washing system with two or more wells (super well boyt method). It is an analysis figure which shows the particle size of the soil particle after the swing washing | cleaning of FIG.

Explanation of symbols

1 …… Ground
1a …… Surface
1b …… Underground
1c …… Water table
1 ₁ …… Sand layer
1 ₂ …… Cohesive soil layer
1 ₃ …… Sand layer below the viscous soil layer
2 …… Well (Super Well Boynt)
2a …… Casing
2b …… Airtight lid
2c …… Strainer
2d …… Sediment pit
2e …… Pumping pump
2f …… Drain pump
2g …… Vacuum pump
2h, 2i …… Piping
2j …… Water tank
3 ... Air cement milk or foam grout supply equipment
3a ... Perforated piping
3b …… Piping
3c …… Valve
4a …… Soil particles
4b …… Free water (groundwater)
4c …… Adsorbed water
4d …… Air or air bubbles
4e …… Vacuum part
5 …… Impermeable wall
6 …… Airtight material
7 …… Structure foundation
8 …… Ground structure
8 ′ …… Prop
8 "…… Horizontal girder
9 …… Grout material

Claims (7)

A perforated pipe (3a) for supplying fresh air or fresh water to the ground (1b) from the ground surface (1a) of the ground (1) in the contaminated soil; A process of covering the ground surface (1a) with an airtight sheet or concrete or asphalt pavement or a new sludge or other airtight material (6) and two or more wells (2) in the ground (1b) A process of pumping groundwater in the vicinity of the ground (1b) by the superwell point method provided with an interval of The process of repeatedly supplying fresh air or fresh water through the perforated pipe (3a) of the grout material supply facility (3) extending from the ground surface (1a) to the ground (1b) (1b) Ground improvement method consisting of the process of returning groundwater. Airtight material (2a) overlaid on the ground surface (1a) when the operation of the super well point method with two or more wells (2) provided at predetermined intervals was stopped or when the operation of the super well point method was stopped The ground improvement method according to claim 1, wherein 6) is removed and air is supplied by natural air supply due to a difference in pressure between the inside and outside of the ground (1b) and the ground surface (1a). In the cohesive ground of the cohesive soil layer (1 ₂ ) and the sand layer (1 ₁ ) ・ (1 ₃ ), the pore water pressure of the sand layer (1 ₃ ) below the cohesive soil layer (1 ₂ ) is more than 2 wells (2) by reducing the pressure in each other and sucked by the super-well point method which are provided at a predetermined interval, according to claim 1, viscous soil layer by the stress load was applied to (1 ₂₎ is compacted dehydrated Clay layer (1 ₂₎ The ground improvement method described. In the cohesive ground of the cohesive soil layer (1 ₂ ) and the sand layer (1 ₁ ) ・ (1 ₃ ), the sand layer (1 ₃ ) below the cohesive soil layer (1 ₂ ) is provided with two or more wells (2). _2. The ground improvement method according to claim 1, wherein a vacuum state is created by evaporating and dehydrating moisture in the viscous soil layer (1 ₂ ) by suctioning and depressurizing each other with a super well point method provided at intervals. . In the cohesive ground of the cohesive soil layer (1 ₂ ) and the sand layer (1 ₁ ) ・ (1 ₃ ), the sand layer (1 ₃ ) below the cohesive soil layer (1 ₂ ) is provided with two or more wells (2). The existing structure foundation (7) and ground structure (8) installed on the unevenly submerged ground surface (1a) by sucking and depressurizing each other with a super well point method provided at intervals. By drilling the lower ground with a curved boring machine and installing the perforated pipe (3a) sideways in the form of passing the left and right sides of the structure foundation (7), A ground improvement method characterized by lifting up the foundation (7) and structure (8) submerged by injecting grout material (9) into the ground. In the ground of the sand layer (1 ₁ ) and (1 ₃ ), the sand layer is submerged in the ground (2) by suctioning and depressurizing each other by the Super Well Point Method with two wells (2) provided at predetermined intervals. The ground improvement construction method according to claim 1, wherein the dynamic consolidation method is performed after the water level of 1b) is lowered. In the operation of the superwell point construction method in which wells (2) are provided at predetermined intervals in the ground (1b) of the sand layers (1 ₁ ) and (1 ₃ ), one of the two wells A ground improvement method characterized by generating a water-tightening action in the ground (1b) by alternately repeating the relationship of giving a pumping action and giving a suction action to the other well every predetermined time.

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