JP2020070582A - Ground displacement suppression method and displacement absorption pile - Google Patents

Abstract

To provide a ground displacement suppression method and a displacement absorption pile capable of improving displacement absorption efficiency and facilitating restoration at a construction site.SOLUTION: A ground displacement suppression method comprises a step arranging a displacement absorption pile 2 for absorbing displacement between a ground improvement area and an adjacent existing structure or peripheral ground to suppress ground displacement and vibration associated with ground improvement using the displacement absorption pile 2, wherein the displacement absorption pile 2 is shaped in an elastic pile shape, of which a part is pushed out to the ground surface side through absorbing the ground displacement and vibration associated with the ground improvement. The displacement absorption pile 2 is produced by: a step penetrating it to a predetermined depth excavating the ground with a penetrating member to be operated up and down and be rotated using injection treatment liquid which is treated by mixing high water-absorbing polymer with water to a gel state as well as is treated to allow its transportation through a piping with a pressure pump by mixing a fluidization agent; and a step injecting and mix or impregnating the injection treatment liquid to a previously positioned soil loosened by excavation in a process of the impregnating and/or pulling out.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a ground displacement suppressing method and a displacement absorbing pile used for the ground displacement suppressing method for preventing displacement of an existing structure or ground on an adjacent ground during foundation construction or ground improvement.

  When ground improvement is performed by sand compaction pile (SCP) method or high-pressure injection method, displacement is generated between the construction area and the object to be displaced in order to give a displacement to the existing structure and surrounding ground on the adjacent ground. A ground displacement suppressing method as illustrated in FIG. 6 (which is disclosed in Patent Document 1) is adopted for the route.

(1) The suppression structure of the same (a) is a method of embedding the steel sheet pile 20 in the displacement transmission path to block or divide the displacement factor. In this configuration, the steel sheet pile may be replaced with a solidification-improving body.
(2) The suppression structure of the same (b) is a method of absorbing the displacement factor by the vertical hole 21 provided in the displacement transmission path. In this configuration, instead of the vertical hole, a mode in which the inside of the hole is simply loosened by excavation (hereinafter, this structure is referred to as a buffer pile), a single elongated bag body is embedded in the vertical hole as disclosed in Patent Document 2, and the bag body is embedded in the bag body. There is also a mode in which a fluid is filled.
(3) In the suppression configuration of the same (c), according to the aspect of Document 2, when a ground displacement different depending on the depth occurs, only a portion of the bag body that undergoes a large ground displacement is largely displaced, and that portion is the maximum displacement amount. This is a countermeasure because the ground displacement is transmitted to the adjacent ground when the ground displacement is reached even after reaching the maximum displacement amount. Constituent features are: a plurality of flexible bags 2 which are embedded in a vertical hole in the vertical direction in a stacked state and filled with fluid; a pressure adjusting means 3 capable of adjusting the pressure of each of the bags 2; A ground displacement detecting means 4 for detecting the ground displacement for each depth and a control means 6 for controlling the pressure adjusting means 3 based on the detected state are provided.

Japanese Patent No. 4459021 JP 2001-152476 A

  Among the above-mentioned conventional ground displacement suppression, in the configuration of the above (1), when the ground displacement exceeds the fixing force of the steel sheet pile due to the ground displacement, the reduction suppression effect becomes low, and in the field recovery work after use, the steel sheet pile etc. Must be removed, which is costly and troublesome. Of the above (2), the structure having only the vertical holes is likely to collapse and is difficult to repair, and the structure having the buffer pile has an insufficient suppressing effect. Further, in the configuration of the above (3), vertical holes are formed, a plurality of bag bodies are laminated, ground displacement detecting means is installed, and connection with the pressure adjusting means is complicated and expensive.

  From the above background, an object of the present invention is to provide a ground displacement suppressing method that absorbs a displacement factor in a displacement transmission path as described in (2) and (3) above, and a displacement absorbing pile used for the method, and to improve absorption efficiency. It is to improve and also make it possible to relatively easily perform field recovery after use. Other purposes will be made clear in the following description.

  In order to achieve the above object, the invention of claim 1 is provided with a displacement absorbing pile between the ground improvement area and an existing structure adjacent to the ground or surrounding ground, and the displacement absorbing pile suppresses ground displacement and vibration associated with ground improvement. In the ground displacement suppressing method described above, the displacement absorbing pile is in the shape of an elastic pile, and a part of the displacement absorbing pile is pushed out toward the ground surface side by absorbing ground displacement and vibration accompanying ground improvement.

The present invention described above is more preferably embodied as in the following claims. That is,
(A) In the invention of claim 2, the displacement absorbing pile is processed by mixing a super absorbent polymer with water to form a gel, and mixing a fluidizing agent so that the displacement absorbing pile can be transferred through a pipe by a pressure pump. Using the injection treatment liquid, the earth is excavated by a penetrating member that is moved up and down and rotated to a predetermined depth, and the injection treatment liquid is discharged to the in-situ soil unraveled by excavation during the penetration or / and extraction process. This is a structure created by mixing or impregnating. Here, the superabsorbent polymer is, for example, the polyacrylate-based superabsorbent resin used in the examples, and it is preferable that the superabsorbent polymer has a water absorption capacity (quantity) of 100 times or more its own weight in water. Further, in this configuration, it is important to treat the super absorbent polymer without using sufficient water, that is, to treat it in a gel form. This is to leave a portion that reacts with water as the super absorbent polymer. Further, in this configuration, it is also important to mix a fluidizing agent so that the gel-like superabsorbent polymer solution can be pumped under pressure. The penetrating member is, for example, an auger (auger drilling machine) used for construction of a pile foundation or the like and an excavator similar thereto. Usually, the injection treatment liquid of the present invention can be discharged from the tip side of the auger.

(A) According to the invention of claim 3, the injection rate of the injection treatment liquid with respect to the in-situ soil is adjusted and managed within the range of 40 to 100% by the penetration speed of the penetration member and the discharge flow rate of the injection treatment liquid. It is a composition. Generally, the higher the injection rate, the more preferable it is. However, if it is lower than 40%, the degree of displacement absorption deteriorates.
(C) The invention of claim 4 further comprises a plasticizing agent capable of losing the viscosity of the fluidizing agent in a forced drainage agent solution which is an aqueous solution of a forced drainage agent capable of draining the water contained in the displacement absorbing pile. Using the mixed restoration solution, the restoration solution is discharged to the displacement absorption pile formed in the ground so as to be mixed or impregnated, so that the N value of the displacement absorption pile after use is increased. . This forced drainage agent is an additive such as calcium chloride that forcibly discharges the water impregnated in the displacement absorption pile. The plasticizing agent is an additive for returning the in-situ soil from the fluidized state to the original state by the fluidizing agent.

(D) On the other hand, the invention of claim 5 is provided between the ground improvement area and an existing structure adjacent to the ground improvement area or the surrounding ground, and suppresses ground displacement and vibration associated with ground improvement. The displacement absorption pile according to any one of 1.

  The inventions of claims 1 and 5 are of the same type as the buffer pile of the above (2) from the point that the ground displacement is absorbed by the displacement absorption pile for ground displacement absorption. However, the displacement absorbing pile of the present invention is in the shape of an elastic pile, and a part of the displacement absorbing pile is pushed to the ground side due to the ground displacement and vibration absorption accompanying the ground improvement. As a result, in the displacement absorbing pile of the present invention, the displacement absorbing action can be visually confirmed. This point cannot be expected with conventional buffer piles, and reliability can be obtained by visual confirmation.

  According to the second aspect of the invention, the displacement absorbing pile of the present invention is constructed by using an injection treatment liquid prepared by mixing a fluidizing agent into a gel aqueous solution of a superabsorbent polymer so as to enable pumping. Is discharged to the predetermined depth while excavating the ground by the penetrating member and / or mixed or impregnated into the in-situ soil unraveled by excavation in the process of penetrating or / and extracting. Therefore, the displacement absorbing pile of the present invention can be easily prepared by using an auger boring machine, a mechanical stirring type column improving machine or the like which is used for usual foundation work and ground improvement. As shown in FIGS. 1 and 2, the advantage of this displacement absorbing pile is that the ground displacement absorbing action can be improved as compared with the above-mentioned buffer pile that is simply unraveled by the spiral, and the present state recovery operation after use is claimed. As you can see, it will be easier.

  In the invention of claim 3, as the displacement absorbing pile of claim 1, it is most efficient to adjust the injection treatment liquid of claim 1 to the in-situ soil so that the injection rate falls within the range of 40 to 100%. Can be absorbed. The lower limit of the injection rate varies depending on the soil properties of the target ground improvement area and the like, but is a value determined to be optimum from various tests and empirical rules conducted by the present inventors.

  The invention of claim 4 is used as an operation of recovering the original ground condition or a condition close to it after using the displacement absorbing pile, for example, by an operation of mixing or impregnating the injection treatment liquid into the in-situ soil. Using equipment such as an auger drilling machine, the restoration solution in which the plasticizing agent is mixed in the forced drainage agent solution is discharged into the displacement absorption pile in the ground to be mixed or impregnated, and the restoration operation can be easily performed with reduced cost. it can.

It is a graph which shows an example which compared the displacement absorption effect in the horizontal direction of the displacement absorption pile by the ground displacement suppression method of the present invention, and the conventional buffer pile (only unfolded with spiral). It is a graph which shows an example which compared the vertical direction displacement absorption effect of the above-mentioned displacement absorption pile and the conventional buffer pile (only unfolded by spiral). The test conditions when investigating the displacement absorption effect of FIG. 1 and FIG. 2 are shown typically, (a) is a top view, (b) is a vertical cross-sectional view. It is a graph which shows an example which compared the displacement absorption pile by the ground displacement suppression method of FIG. 1 and FIG. 2, and the depth-N value (conversion N value) after the restoration process. (A) is a schematic cross section of the displacement absorption pile in the state before sand pile construction, (b) is a schematic cross section of the displacement absorption pile in the sand pile construction state. (A) to (c) are FIG. 5 and FIG. 6 and FIG. 1 disclosed in Patent Document 1.

  Hereinafter, a specific configuration of the ground displacement suppressing method of the present invention will be clarified. In this description, the ground suppression method of the present invention is described with reference to FIG. 3, which is performed in an embodiment, and then simply disentangled by the displacement absorption pile of the method of the present invention and a spiral of a conventional auger boring machine as a comparative example. Example 1 when investigating the displacement absorption effect of the buffer pile and Example 2 of restoring the displacement absorption pile will be described.

(Displacement absorption pile for ground displacement suppression) In Fig. 3, this ground displacement suppression method schematically shows the on-site experimental situation when the ground displacement countermeasure effect of Fig. 1 and Fig. 2 is investigated. A plurality of displacement absorbing piles 2 for absorbing displacement are provided between the existing structure adjacent to and the surrounding ground B, and the displacement absorbing piles 2 suppress the ground displacement and vibration accompanying the ground improvement. The displacement absorption pile 2 of the main part is a pre-formed predetermined injection treatment liquid, for example, as a penetrating member that is penetrated or pulled out by an elevating mechanism for civil engineering work, and is used as an original position under the ground through a spiral of an auger drilling machine. It is formed by mixing with soil. That is, each displacement absorption pile 2 penetrates to a predetermined depth while excavating the ground by a spiral of an auger boring machine that is raised and lowered and rotated, and is in-situ soil that is unraveled by excavation in the penetration or / and extraction process. It is created by discharging the injection treatment liquid into and mixing or impregnating it.

  Here, the injection treatment liquid is prepared by mixing a superabsorbent polymer with water and treating it in a gel form, that is, in a semisolid state such as agar or pudding and having no fluidity, and then the gel form of the superabsorbent polymer. The fluidizing agent is mixed into the molecule and processed so that it can be transferred through a pipe by a pressure pump. The selection criteria and action of the superabsorbent polymer, water and superplasticizer used will be clarified below.

(1) Super Absorbent Polymer (hereinafter referred to as SAP) is a polymer used as an absorber of, for example, a paper diaper and has a high water retention property, and is an absorbent polymer, a super absorbent resin, It is also called a polymer absorber. This SAP is a crosslinked body of hydrophilic linear or molecular polymers, and has a high water absorption power and does not have or has very low viscosity increasing property, cohesive property and dispersibility. In addition, SAP is generally assumed to have a water absorption capacity (amount) of 10 times or more its own weight in water, but use a water absorption capacity (amount) 100 times or more its own weight in water. Is preferred.

  That is, among the water-absorbing polymers, synthetic polymer-based SAPs include polyacrylate-based, polysulfonate-based, maleic anhydride-based, polyacrylamide-based, polyethylene oxide-based, etc. Accordingly, the absorption capacity for water can be changed by changing the type of the hydrophilic resin chain serving as the trunk, and the strength of the gel swollen by absorbing water can be changed by changing the crosslinking density. Therefore, for example, even a polyacrylic acid salt-based water-absorbing polymer may have dispersibility or have a water-absorbing power less than 10 times its own weight. In the present invention, such a water-absorbing polymer having a low water absorption is excluded, and SAP having a water absorption of 10 times or more, preferably 100 times or more, of its own weight in water is used, for example, a polyacrylate SAP. As a commercially available product, for example, a polyacrylic acid cross-linking type “HIMO SUB 300” manufactured by Himo Co., Ltd. used in the examples can be mentioned. It is a white powder and has a water absorption capacity (quantity) of 300 times or more in water.

(2) Water is used in an amount such that the superabsorbent polymer is gelled. In this case, the superabsorbent polymer can absorb and retain several hundreds to about one thousand times its own weight of water, but if cations such as sodium and potassium are present in the water, the absorption capacity is significantly reduced. For this reason, it is preferable to use neutral tap water as the water to be used, avoiding industrial water and seawater containing various components that affect the superabsorbent polymer.

(3) The fluidizing agent is an additive that increases the viscosity of the gel-like superabsorbent polymer added to water, suppresses the separation of water, and improves the pumpability. Anionic polymer flocculants that increase viscosity and suppress the separation of water are preferable, and nonionic polymer flocculants, cationic polymer flocculants and the like may also be used. These are excellent in the ability to retain water inside the hydrophilic group of the polymer and the network of the polymer. As the anionic polymer flocculant, a homopolymer of acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamido 2-methylpropanesulfonic acid, vinyl sulfonic acid, styrene sulfonic acid or the like or a copolymer with acrylamide is used. Is mentioned.

  Next, a suitable formulation example and preparation method of the injection treatment liquid of the present invention will be described. First, the blending amount of water with respect to SAP varies depending on the type of SAP, but is the ratio at which SAP becomes gel-like. In the example, water per 1,000 L was put in the mixer, and 10 kg of SAP (Hymosab 300) was put therein and stirred, so that the SAP absorbed water was gelled. Further, the amount of the fluidizing agent to be mixed with the gelled SAP is such a proportion that the fluidization can be maintained by pumping. If the fluidizing agent is too small, it will not fluidize, and it will be separated or clogged in the pipe to make it impossible to pump. On the contrary, if it is too large, the fluidizing effect will not change, but rather the cost will increase. In the examples, 5 kg of a fluidizing agent (anionic polymer flocculant) was added to the gel-like SAP in the mixer and stirred to prepare a fluid injection treatment liquid that could be pumped.

  In the construction of the displacement absorbing pile, for example, an auger drilling machine or an excavator similar to the auger drilling machine is used, and the injection treatment liquid of the present invention is discharged from the auger tip side to mix or impregnate in-situ soil under the ground. In the embodiment, the earth is excavated by an auger boring machine (spiral diameter: 500 mm) while excavating the ground to a predetermined depth, and the injecting treatment liquid is discharged and mixed or impregnated into the in-situ soil unraveled by the excavation process. Displacement absorption pile 2 was created. In this case, the injection rate of the injection treatment liquid is controlled by the penetration rate and the injection amount, and is usually in the range of 40 to 100%, more preferably about 60%. Note that the injection treatment liquid may be discharged by a penetration and extraction process or a withdrawal process. The created displacement absorbing pile 2 has a property like soft rubber, and when pressed with a finger, a reaction force is felt. Moreover, even if it is squeezed, it is not easily dehydrated. As shown in FIG. 4, the hardness is as small as about 1 or less in the converted N value at the depth of 2 to 5 m.

(Method of Restoring Displacement Absorption Pile to Original Ground) Since the displacement absorption pile 2 after use has an N value (converted N value) of about 1 or less as shown in FIG. 4, it is preferable to perform a restoration process. .. In this restoration operation, a restoration solution is used in which a forced drainage agent solution, which is an aqueous solution of a forced drainage agent that enables the water contained in the displacement absorption pile 2 to be drained, is mixed with a plasticizing agent that can lose the viscosity of the fluidizing agent. To do. This restoration solution can be restored to the original ground or a state close to the original ground by being discharged and mixed or impregnated into the displacement absorption pile 2 formed in the ground.

  Here, the forced drainage agent is a salt such as calcium chloride or sodium chloride that forcibly discharges the water impregnated in the displacement absorption pile. Functionally, for example, when polyacrylate SAP absorbs water, ions are ionized, but when a forced drainage agent solution, which is an aqueous solution of the forced drainage agent, is applied from the outside, the ion concentration inside and outside the molecule is outside. It is thick and thin inside, so we apply the phenomenon that water flows out from inside due to osmotic pressure. As the forced drainage agent, magnesium chloride or aluminum chloride may be used.

The plasticizing agent ionically adsorbs the fluidizing agent mixed in the in-situ soil to make it insoluble and lose its viscosity. For example, when the fluidizing agent is an anionic polymer agent, a cationic polymer agent having a molecular weight of 10 ⁴ to 10 ⁷ is used. When the fluidizing agent is a cationic polymer agent, an anion having a molecular weight of 10 ⁴ to 10 ⁷ is used. Use a high-molecular-weight agent. This electrically neutralizes the fluidizing agent and separates it from the water to return it to its original soil. That is, the interstitial water between soil particles returns to normal water having no viscosity, and the friction of soil particles is recovered. If the addition amount is too small, the fluidized soil will not be plasticized, and if the addition amount is too large, the cost will increase.

  Next, as a method for preparing the reconstitution solution, in the examples, 1,000 L of water was put in a mixer, 100 kg of calcium chloride and 8 kg of a plasticizer were added thereto, and the mixture was stirred. As the construction method, an auger drilling machine is used, and the restoration solution is discharged from the tip side of the auger while being injected. In this case, the injection rate of the reconstitution solution is controlled by the penetration rate and the injection amount, and is usually in the range of 5 to 15%, more preferably about 10%. The restoration solution may be discharged by a penetration and extraction process or a withdrawal process. By the above restoration process, the N value (converted N value) of the displacement absorption pile 2 becomes about 2.5 or more in hardness at the depth of −0.5 to −5.0 m from FIG.

(Embodiment 1) In Embodiment 1, in FIG. 3, the displacement absorbing piles 2 of the present invention are arranged at equal intervals at the boundary between the ground improvement area A and the existing structure or the surrounding ground B (hereinafter referred to as the surrounding ground B). This was created. On the surrounding ground B, at the intermediate position of the six displacement absorption piles 2 (between the third and fourth positions from the end), four ground surface displacement gauges 4 are arranged on a straight line at 1000 mm intervals as shown in the figure. installed. After that, in the ground improvement area A, as shown in the figure, a total of 9 sand piles 1 were laid by the sand press-fitting static compaction method, three in each of three rows. The first row sand pile 1 is 1000 mm from the pile core of the displacement absorption pile 2, the second row sand pile 1 is 1700 mm from the first row sand pile 2, and the third row sand pile 1 is the second row sand pile. 2 to 1700 mm apart. In each row, the three sand piles 1 are the six displacement absorption piles 2 between the first and the second from the end, the third and the fourth from the end, and the fifth and the sixth from the end. It has been placed in between.

  On the other hand, as a comparative example, in a comparative example area different from the above-mentioned example area, instead of the displacement absorbing pile 2 of FIG. 3, a buffer pile simply unraveled by a spiral of a conventional auger drilling machine. 3 and the sand pile 1 were placed under the same conditions as the displacement absorption pile 2 and the sand pile 1 of the example. Of course, the comparative example area has the same ground property or state as the example area.

(Results) FIGS. 1 and 2 are graphs showing the test results of the above Examples and Comparative Examples. 1 and 2 show horizontal displacements (mm) and vertical displacements (mm) measured by surface displacement gauges 4 at locations 2m, 3m, 4m, and 5m away from the pile core of one row of sand piles 1. ) Is shown. As for horizontal displacement, according to FIG. 1, when comparing the location 2 m away from the pile core of the first row sand pile 1 and the location 3 m away from it, the displacement absorbing pile 2 is displaced by about 11 mm and 9 mm, while the buffer pile is In No. 3, the displacement is about 20 mm and 19 mm. Therefore, in the displacement absorbing pile 2, as compared with the buffer pile 3, a ground displacement suppressing effect of about 2 times in horizontal displacement is obtained. As for the vertical displacement, according to FIG. 2, when comparing the location 2 m away from the pile core of the first row sand pile 1 and the location 3 m away from it, the displacement absorption pile 2 is displaced about 5 mm and 4 mm, while the buffer pile is In No. 3, displacement is about 14 mm and 7 mm. Therefore, in the displacement absorbing pile 2, as compared with the buffer pile 3, as a ground restraining effect, a restraining effect about twice or more can be obtained even in the vertical displacement.

  By the way, each of the displacement absorption piles 2 described above absorbs the ground displacement and the like caused by the construction of the sand piles 1. However, the displacement absorption material (in-situ soil is mixed with or impregnated with the injection treatment liquid of the present invention) is absorbed by the absorption. A part of it is extruded as if it were squeezed to the ground surface. FIG. 5 schematically shows the phenomenon. Although the schematic cross-sectional view of (a) shows the displacement absorbing pile 2 constructed in the above-described manner, the sand pile 1 is not yet placed in the ground improvement area A of the adjacent ground. The schematic cross-sectional view of the same (b) is a schematic representation of elastic deformation of the displacement absorbing pile 2 in a state in which a predetermined number of sand piles 1 are constructed in the ground improvement formula A.

  In this configuration, the displacement absorbing pile 2 is entirely or locally pressed from one side or the corresponding side surface of the sand pile 1 by the displacement stress (load applied to the corresponding side surface or displacement stress) caused by ground displacement or vibration accompanying the sand pile construction. , A part of it is pushed out from the ground surface. In other words, since this phenomenon does not occur in the conventional buffer pile 3, it is based on the elastic pile shape together with the fluidity which is one of the physical properties of the displacement absorbing pile 2. The elastic pile shape gives a sticky or elastic feeling when the displacement absorbing pile is touched with a hand, for example.

(Example 2) In this Example 2, a plurality of displacement absorption piles were constructed in the same manner as in Example 1 above, and one week after construction, the converted N value of the two displacement absorption piles (N value in the table is omitted. ) Was measured. The remaining four displacement absorption piles 2 were subjected to the restoration treatment of the present invention, and the converted N value of the two displacement absorption piles was measured 11 weeks after the restoration treatment. Table 1 below summarizes the measurement results.

(Table 1)

  Further, FIG. 4 shows the relationship between the depth (m) and the converted N value. That is, it can be seen that the displacement absorption pile of the present invention becomes harder by about 1.5 or more in the converted N value at the depth of −0.5 to −5.0 m by the restoration process. The converted N value is a value equivalent to the N value in the standard penetration test calculated by counting the number of rotations required to rotate the rod and slipping it into 25 cm in the Swedish Unding test prescribed by JIS A1221. Is.

  It should be noted that the above embodiments and examples do not limit the present invention in any way. The present invention only needs to include the technical elements specified in the claims, and various details can be changed as necessary.

1-sand pile 2-displacement absorption pile 3-buffer pile 4-ground displacement meter (ground displacement detector)
A: Ground improvement area B: Existing structure or surrounding ground

Claims (5)

A method for suppressing displacement of ground, which is provided with a displacement absorbing pile between an existing structure adjacent to the soil improvement area or the surrounding soil, and suppresses the displacement and vibration of the soil due to the soil improvement by the displacement absorbing pile,
The displacement absorbing pile has a shape of an elastic pile, and a part of the displacement absorbing pile is extruded to the ground surface side by absorbing ground displacement and vibration accompanying ground improvement, which is a method for suppressing ground displacement. The displacement absorbing pile is processed by mixing the superabsorbent polymer with water to form a gel, and using an injection treatment liquid treated with a fluidizing agent so that the fluid can be transferred through a pipe by a pressure pump.
Created by excavating the ground with a penetrating member that is moved up and down and rotated while penetrating to a predetermined depth, and discharging and mixing or impregnating the pouring treatment liquid into the in-situ soil that is unraveled by excavation during the penetration or / and extraction process. The ground displacement suppressing method according to claim 1, wherein the ground displacement suppressing method is performed.   The injection rate of the injection treatment liquid with respect to the in-situ soil is adjusted and managed to fall within a range of 40 to 100% by the penetration speed of the penetration member and the discharge flow rate of the injection treatment liquid. Ground displacement control method.   In the forced drainage agent solution, which is an aqueous solution of the forced drainage agent that enables the water contained in the displacement absorption pile to be drained, a restoration solution in which a plasticizing agent that allows loss of the viscosity of the fluidizing agent is mixed is used to perform the restoration. A method for suppressing ground displacement, characterized in that the solution is discharged to the displacement absorbing pile formed in the ground and mixed or impregnated to restore the N value of the displacement absorbing pile after use.   The displacement absorbing pile according to any one of claims 1 to 3, which is provided between the ground improvement area and an existing structure adjacent to the ground improvement area or a surrounding ground to suppress ground displacement and vibration associated with the ground improvement.

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