JP5971537B1 - Ground improvement method - Google Patents

Abstract

The present invention provides a ground injection device and a ground improvement method capable of more efficiently infiltrating a ground improvement material into a required location in the ground with a large discharge amount and low-pressure infiltration between soil particles. A plurality of injection pipes 2 are built in a hole 1 and a columnar penetration source 4 is provided at an injection material discharge port portion at the tip of each injection pipe 2. Between the hole wall of the hole 1 and each injection pipe 2, a filter layer S filled with dredged sand or the like and a seal packer layer BP containing bentonite are formed in alternate layers, and a sealing material CB made of cement bentonite or the like on the top. Is filled. The column penetration source 4 of each injection pipe 2 is located in the filter layer S of different height, and the ground improvement material discharged from each injection pipe 2 is a filter layer S in which the upper part and the lower part are restrained by the seal packer layer BP. It penetrates into a plurality of injection stages A, B, C, and D in the ground from the hole wall of the hole 1 with a width according to the height of the filter layer S. [Selection] Figure 4

Description

The present invention constitutes a columnar seepage source by an injection pipe installed in a drilling hole formed in the ground, a filter layer mainly composed of sand filled between the injection pipe and the drilling wall, and a sealing means. it relates ground improvement method using a ground injection equipment to.

  As the ground injecting material to be permeated into the ground, solidified ground improving materials such as silica-based grout materials and plastic grout materials, micro bubbles for ground improvement, and the like are used.

Incidentally, ground improvement method referred to in the present application, or to improve the direct ground strength by caking of soil improvement material, if the ground by unsaturated improve liquefaction strength by injection into the ground of the micro-bubble This refers to a method of improving the properties of the ground, and does not include ground purification technology by removing or fixing pollutants, and the soil injection material referred to in this application is an injection material for the purpose of soil improvement and is intended for soil purification. Does not include soil cleaner.

  Patent Document 1 discloses an injection pipe device and an injection pipe built in a drilling hole as an injection pipe apparatus and an injection method capable of uniformly injecting as large a volume of injection material as possible under low pressure injection. A check valve that opens and closes an injection material discharge port provided in the injection pipe, and a columnar space water guide member that covers a certain range in the tube axis direction including the check valve are attached, respectively, and the drilling wall and the injection A columnar seepage source consisting of a columnar space water-conducting member covered with the seal grout between the drilling wall and the injection tube is fixed in the tube axis direction. Even if a large volume of injection material is injected into the surrounding ground from the hole wall of the drilling hole, the injection material will seal grout from a certain length covered with the columnar space water conveyance member. It can be broken and injected at low pressure by columnar injection. Technology that was so that has been disclosed.

  Patent Document 2 discloses curing for solidifying a non-alkali silica sol using ferric sulfate and / or polyferric sulfate as an arsenic insolubilizing agent and a non-alkali silica sol as a soil solidifying agent as an infusion solution for preventing arsenic diffusion. By using an acid that does not contain a phosphorus atom as the acid having the function of the agent and pH adjuster, the gelation time of the chemical solution itself can be lengthened appropriately, and arsenic insolubilization and soil solidification after injection can be achieved. A technique for purifying contaminated soil that can be performed quickly and can be solidified with high strength is disclosed.

  In Patent Document 3, in the in-situ purification method such as bioremediation, the injection / penetration of the cleaning solution by the multi-point injection is performed within the same time so as to restrain each other in the range to be handled according to the ground conditions. In this case, the purification liquid is uniformly infiltrated into the target area by performing the synchronization so that the predetermined amount of injection is constrained and completed. A technique for preventing the object from being pushed out of the target range is disclosed.

Japanese Patent No. 4848553 Japanese Patent No. 5209128 Japanese Patent No. 5569618

  For example, in bioremediation, the purification solution is a non-solidifying aqueous solution in which a microbial nutrient is dissolved in water, and its viscosity and underground behavior are almost the same as water. By the way, since such a purifying liquid has no caking property, when it is injected into the ground, it flows to a portion having high water permeability, and when the ground is an alternating layer, it is difficult to permeate into silt and clay. Moreover, the purification solution itself moves together with the groundwater by the injection pressure without affecting the soil permeability.

  Non-hardening cleaning liquid does not gel when injected, so it penetrates to any extent, easily deviates along rough layers and layer boundaries, and at the same time it also extrudes contaminants or accumulates contaminants. It is difficult to in-situ clean up because it does not penetrate the board.

  For example, the injection by the conventional general double packer method is injection at every depth (usually 33 cm) in one injection tube, but injection at an arbitrary injection stage (discharge port) (normally a discharge amount of 10 per minute). Liters to 15 liters), and when moving to the next injection stage (discharge port) and injecting, the purifying liquid injected in advance is pushed out by the pressure of the injection, so that the purifying liquid becomes a rough soil layer. As a result, the contaminants are pushed out and diffused easily, and there is a problem that the cleaning solution does not easily act on the contaminants in the fine-grained soil.

  Moreover, when the silica grout with gelation and the purification material are injected in combination (Patent Document 2), the purification material in the gelled purification solution does not effectively act on the pollutant, or in the soil due to the presence of the gel. There is a problem that the activation of microorganisms is inhibited. In addition, when a purification material that does not cause gelation is injected, the purification solution is insufficiently penetrated into the ground where the contaminants are distributed by deviating from the soil layer where the purification material easily penetrates. For this reason, there is a problem that the environment of the activity of microorganisms is not sufficiently prepared, and the concentration reduction of the pollutant does not proceed.

  In addition, natural injection is a method of infiltrating the purification solution from the ground into the ground by gravity through a well provided with a perforated tube or slit at the depth of the aquifer, but in natural injection, water permeability is good. There is a problem that the cleaning solution penetrates into the soil, but does not penetrate into silt or clay.

  The problem concerning the penetration into the ground is the same in the injection of ground injection materials for improving the ground such as silica-based grout materials and plastic grout materials.

  The technique described in Patent Document 3 is intended to solve such a problem, but efficient control may be difficult depending on ground conditions and the like. In addition, there is a problem in that the seal grout formed around the injection pipe is broken by using the injection pressure of the ground injection material to cause osmotic injection to cause variations.

  The present invention aims to solve the above-mentioned problems in the prior art, and more efficiently by injecting the ground injecting material into the required place in the ground with a large discharge amount and low-pressure permeation between soil particles. The purpose is to provide a ground injection device and a ground improvement method that can be infiltrated and the gel properties and permeability of the injection material are not affected by the chemical properties (especially alkalinity and calcium salt) and strength of the seal grout. It is said.

The ground injection device used in the present invention is installed in a drilling hole formed in the ground, an injection pipe having an injection material discharge port at one or a plurality of locations in the pipe axis direction, an outer peripheral portion of the injection pipe, and the A filter layer mainly composed of sand filled below including the injection material discharge port position between the drilling wall of the drilling hole, and between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole. It consists of a sealing material filled above the position of the injection material discharge port, and the consolidation or microbubble ground injection material for ground improvement discharged from the injection material discharge port is constrained at the top by the seal material. The filter layer is configured to penetrate through the hole wall into the ground through the entire length of the filter layer.

The ground injection material used in the present invention, for example, silica-based grout, other curable ground injection material such as plastic grout material include micro bubble to improve liquefaction strength by desaturate Ground .

  Because these ground injection materials are uniformly dispersed in the filter layer mainly composed of sand, the injection material injected from the injection material discharge port of the injection pipe penetrates into the target formation from the drilling wall, The injection material can be permeated at a low pressure with a large discharge amount. In addition, the interval between the injection tubes can be increased accordingly.

  In the ground injection device of the present invention, in the injection of the ground injection material, the filter layer mainly composed of sand functions as a columnar penetration source, the penetration rate per unit penetration area is small with a large discharge amount, and the injection pressure is low. Large volume osmotic injection is possible.

  In the present invention, the filter layer mainly composed of sand has a function as a columnar penetration source. However, a double columnar penetration source can be obtained by using a conventionally known column penetration source for the discharge port portion of the injection tube. May be formed. In addition, for the discharge portion of the injection tube, use one having one or a plurality of discharge ports, a combination of a plurality of injection capillaries with different discharge port heights, or a device whose injection position can be changed to a double packer system. Also good.

  The sealing material filled above the filter layer has water tightness and is intended to prevent the injecting material from flowing out of the target formation. In addition to water tightness such as cement bentonite, it is hardened and strong. It is preferable to use a material comprising

The ground injection device according to another embodiment used in the present invention is installed in a drilling hole formed in the ground, and has an injection pipe having an injection material discharge port at one or a plurality of positions in the pipe axis direction, and the injection pipe A seal packer layer including bentonite formed above, above and below the position of the injection material discharge port between the outer periphery of the injection hole and the hole wall of the hole, and the outer periphery of the injection tube and the hole A filter layer mainly composed of sand that is filled below or above and below the seal packer layer between the drilling wall and a consolidation for ground improvement discharged from the injection material discharge port ground grout sex or microbubbles, to characterized in that the top at the sealing packer layer, or the upper and lower becomes configured to penetrate the ground in from the drilling wall through the filter layer constrained .

Again, with respect to the ground injection material for soil improvement, other caking injection material such as silica-based grout and plastic grout material, it can be utilized Ma Ikurobabu Le as grout.

  In addition, the discharge port portion of the injection tube also has one or a plurality of discharge ports, a combination of a plurality of injection capillaries with different discharge port heights, a type in which the injection position can be changed to a double packer system, columnar penetration Sources etc. are applicable.

  For the seal packer layer, bentonite pellets having water absorbability and the like can be used. Bentonite pellets are commercially available in granular form, etc. By inserting bentonite pellets into the upper part of the filled filter layer, it absorbs moisture in the hole and swells, and a seal packer layer with water-stopping properties. Is formed.

  Depending on the soil distribution of the target ground, a filter layer mainly composed of sand is provided corresponding to the position of the highly permeable sand layer and silt layer, and bentonite is added to the boundary part and the boundary part with the low permeable clay layer. A seal packer layer is provided so that the injected material efficiently penetrates into the targeted formation through the filter layer.

  Moreover, it is preferable that the particle size of the sand forming the filter layer is better in water permeability than the surrounding soil.

  When the filter layer mainly composed of sand is formed in the vertical direction, the upper part of the uppermost filter layer or the upper part of the uppermost seal packer layer is filled with a sealing material such as cement bentonite as necessary.

  In addition, the filter layer mainly composed of sand depends on the construction conditions, but by making it a pillar shape whose height is larger than the diameter, the injection material as the ground improvement material is permeated into the pillar shape with a wide width according to the height. Can be made.

Ground improvement method of the present invention is a method using a note pipe device described above,
(1) excavating the ground using a casing and forming a hole in the ground;
(2) installing an injection pipe having an injection material discharge port in one or a plurality of places in the pipe axis direction in the drilling hole;
(3) While pulling up the casing, the sand is filled up to a position above the injection material discharge port position between the outer periphery of the injection pipe and the drilling wall of the drilling hole to form a filter layer mainly composed of sand. And a process of
(4) A step of filling a sealing material such as a bentonite-containing seal packer layer or cement bentonite above the filter layer between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole while pulling up the casing. When,
(5) a step of discharging the ground injection material of solidification or microbubbles for ground improvement from the injection material discharge port of the injection tube;
Have
The ground injection material discharged from the injection material discharge port is infiltrated into the ground from the hole-drilling wall through the filter layer whose upper portion is restricted by the sealing material.

As ground grout, other caking injection material such as silica-based grout and plastic-like grout, that can be utilized Ma Ikurobabu Le as injection material and, in as described above with respect to the configuration of each injection tube is there.

  In the case of using the double packer method in the injection from the injection tube, the injection tube has an injection outer tube having an injection material outlet at one or a plurality of locations in the tube axis direction, and an injection installed in the injection outer tube. It consists of an inner tube, and the ground injection material discharged from the injection inner tube into the injection outer tube is discharged from the injection material outlet of the injection outer tube and penetrates from the hole wall into the ground through the filter layer mainly composed of sand. It becomes a form.

  The injection inner pipe is provided with a double packer above and below the discharge port at the tip, and the injection material passes through the filter layer from one or more discharge ports having a check valve of the injection outer tube located between the upper and lower double packers. It is injected into (Fig. 6).

The ground improvement construction method in another aspect of the present invention,
(1) excavating the ground using a casing and forming a hole in the ground;
(2) installing an injection pipe having an injection material discharge port in one or a plurality of places in the pipe axis direction in the drilling hole;
(3) While pulling up the casing, the sand is filled up to the lower side including the injection material discharge port between the outer periphery of the injection pipe and the drilling wall of the drilling hole to form a filter layer mainly composed of sand. And a process of
(4) While pulling up the casing, a seal packer layer containing bentonite or a layer of a sealing material such as cement bentonite is formed above the filter layer between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole. A process of
(5) -1 When there is an injection material discharge port of the injection pipe above the seal packer layer, while pulling up the casing, between the outer peripheral portion of the injection pipe and the hole wall of the hole Forming a filter layer mainly composed of sand by filling the sand up to the lower position of the injection material discharge port in between,
(5) -2 a step of forming a seal packer layer above the filter layer between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole while pulling up the casing;
(5) -1 and (5) -2 are repeated one or more times, and
(6) a step of discharging the ground injection material of solidity or microbubbles for ground improvement from the injection material discharge port of the injection tube;
Have
The ground injection material discharged from the injection material discharge port is infiltrated into the ground from the hole wall through the filter layer in which an upper part or an upper part and a lower part are constrained by the seal packer layer.

As ground grout for soil improvement, silica grout injection of caking of the injection material, such as plastic-like grout, and can be utilized such as ground injection of micro bubble, when using a double packer method In addition to the above, the configuration of various injection tubes is as described above.

  The ground injection device of the present invention includes a filter layer mainly composed of sand that promotes penetration of a ground injection material for ground improvement around an injection pipe, and a sealing material such as cement bentonite and bentonite pellets that prevent penetration of the ground injection material. The seal packer layer containing bentonite such as is formed in alternate layers, and the injection material discharge port of the injection tube is configured to be located in the filter material layer mainly composed of sand, so that it is discharged from the injection material discharge port. The ground injection material for ground improvement is configured to penetrate into the ground through a filter layer mainly composed of sand constrained by a seal packer layer with a seal material, and the ground injection material is necessary in the ground. It is possible to infiltrate efficiently at a low pressure with a large discharge amount at low pressure by inter-soil particle infiltration.

  In the case of the conventional seal grout, the seal grout component may cause a chemical change with the ground injection material. On the other hand, a strong seal grout such as cement bentonite covers the discharge port of the injection pipe. On the other hand, since the ground injection device of the present invention permeates through the filter layer mainly composed of sand, there is no problem with respect to chemical change or smooth discharge during injection.

It is a vertical sectional view showing a construction procedure in one embodiment of the present invention. It is a schematic diagram which shows the structure of the multipoint ground injection | pouring apparatus in the case of performing multipoint simultaneous injection | pouring regarding this invention. It is a vertical sectional view showing a construction procedure in another embodiment of the present invention. It is the vertical sectional view which showed roughly the case where simultaneous injection is performed to each layer of the ground. It is the vertical sectional view which showed roughly the case where it inject | pours into the specific layer of the ground. It is the vertical sectional view which showed roughly the case where it constructs by applying the double packer construction method to the present invention. It is a schematic diagram which shows the apparatus structure in the case of performing multipoint simultaneous injection | pouring about the ground improvement construction method corresponding to FIG. It is a schematic diagram which shows other embodiment in the case of performing multipoint simultaneous injection | pouring. It is the figure which showed the standard cross section of the soil columnar figure in an experiment, an injection | pouring test hole, and an observation hole (observation well). It is a plane layout view of an injection test hole, an observation hole (observation well), and a confirmation hole (boring) in a demonstration experiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments.

FIG. 1 shows a construction procedure in one embodiment of the present invention, and construction can be performed by the following procedure.
(1) Excavate the ground using the casing 3 to form a hole 1 in the ground (see FIG. 1 (a)).
(2) The injection tube 2 is installed in the drilling hole 1 (see FIG. 1 (b)). The illustrated example is a case where the columnar permeation source 4 is provided around one or a plurality of discharge ports at the tip of the injection tube 2. This columnar penetration source 4 is provided at a position corresponding to the depth of the layer to be injected in the ground.
(3) While pulling up the casing 3, sand such as dredged sand is filled between the outer peripheral portion of the injection pipe 2 and the drilling wall of the drilling hole 1 to the upper side of the columnar penetration source 4 to form a columnar filter layer S made of sand. It forms (refer FIG.1 (c)-(d)).
(4) While pulling up the casing 3, the bentonite pellets obtained by processing bentonite into a granular shape are filled on the filter layer S between the outer peripheral portion of the injection pipe 2 and the hole wall of the hole 1. Moisture is absorbed and swelled in the bentonite pellet drilling hole 2 to form a watertight seal packer layer BP (bentonite pellet) (see FIG. 1 (e)).
(5) While the casing 3 is further pulled up, a sealing material CB (cement bentonite) such as cement bentonite is filled on the seal packer layer BP between the outer peripheral portion of the injection pipe 2 and the drilled wall of the drilled hole 1 ( (See FIG. 1 (f)).
(6) The ground injection device of the present invention is formed by the above procedure, and the ground injection material for ground improvement is discharged from the columnar seepage source 4 provided at the discharge port of the injection pipe 2 (see FIG. 1 (g)). . The discharged ground injection material smoothly penetrates the columnar filter layer S mainly composed of sand with high water permeability, and allows a large volume of ground injection material to permeate the target ground layer in the ground at low pressure from the drilling wall. Can do.

  Depending on the depth of the ground to be injected and other conditions, the procedure (4) described above may be omitted and the filter layer S may be directly filled with a sealing material CB such as cement bentonite. .

Ground grout is not limited to solidifying the injected material, such as silica-based grout and plastic-like grout may be unsaturated material such as a micro bubble in accordance with the purpose of construction.

  FIG. 2 relates to the present invention and schematically shows the configuration of a multipoint ground injection apparatus when performing multipoint simultaneous injection.

  The multi-point ground injection device A includes a ground improvement material storage tank 10 and a number of unit pumps 12 that are operated by independent drive sources 15 such as motors and are connected to and controlled by a central control device 17. 2 and a plurality of injection pipes 2 respectively connected through the unit pumps 12 and the pipes 11 arranged at injection points in the ground.

  A large number of independent unit pumps 12 are provided with a rotational speed transmission 15 such as an inverter connected to a centralized control device 17, and each of the conduits 11 connecting the unit pump 12 and the injection pipe 2 is concentrated. A flow pressure detector 13 connected to the management device 17 and controlled is provided.

  With the above-described configuration, the flow rate and / or pressure data signal from the flow rate pressure detector 13 is transmitted to the central control device 17, and the ground injection material in the injection material storage tank 10 is arbitrarily injected by the operation of each unit pump 12. It can be pumped to each injection pipe 2 at a speed, injection pressure or injection amount, and can be injected into the ground simultaneously from a plurality of filter layers S mainly composed of sand.

FIG. 3 shows a construction procedure in another embodiment of the present invention, and construction can be carried out according to the following procedure.
(1) The ground is excavated using the casing 3, and the drilling hole 1 is formed in the ground (see FIG. 3 (a)).
(2) A plurality of injection pipes 2 for different formations are installed in the borehole 1 (see FIG. 3 (b)). The illustrated example is a case where the columnar permeation source 4 is provided around one or a plurality of discharge ports at the tip of each injection tube 2. This columnar penetration source 4 is provided at a position corresponding to the depth of the layer to be injected in the ground.
(3) While pulling up the casing 3, sand such as dredged sand is filled between the outer peripheral portion of the injection pipe 2 and the drilling wall of the drilling hole 1 up to the upper part of the columnar permeation source 4 at the lowest stage, and the filter layer S is made of sand. (See FIG. 3C).
(4) While pulling up the casing 3, the bentonite pellets obtained by processing bentonite into granules are filled on the lowermost filter layer C between the outer peripheral portion of the injection pipe 2 and the drilled wall of the drilled hole 1. The bentonite pellet absorbs moisture in the hole 2 and swells to form a watertight seal packer layer BP (bentonite pellet) (see FIG. 3 (d)).
(5) While further pulling up the casing 3, the second-stage filter layer S and the seal packer layer BP are formed in the same manner (see FIG. 3 (e)).
(6) Similarly, a third-stage filter layer S, a seal packer layer BP, and a fourth-stage filter layer S are formed (see FIG. 3 (f)).
(7) While further lifting the casing 3, a sealing material CB made of cement bentonite or the like is placed on the uppermost (fourth stage) filter layer S between the outer periphery of the injection pipe 2 and the hole wall of the hole 1. Fill (see FIG. 3 (g)). In some cases, a fourth-stage seal packer layer BP made of bentonite pellets is formed on the uppermost (fourth-stage) filter layer S, and a sealing material CB made of cement bentonite or the like is filled thereon. Also good.
(8) The ground injection device of the present invention is formed by the above procedure, and the ground injection material for ground improvement is discharged from the columnar seepage source 4 provided at the discharge port of the injection pipe 2 (see FIG. 3 (h)). . The discharged ground injection material smoothly penetrates the filter layer S mainly composed of sand with high water permeability for each layer where the columnar penetration source 4 is located, and a large volume of ground injection material is injected into the ground at a low pressure from the drilling wall. It can penetrate into the target strata.

Ground grout is not limited to solidifying the injected material, such as silica-based grout and plastic-like grout may be a micro-bubble in accordance with the purpose of construction.

  FIG. 4 is a vertical sectional view schematically showing a case where simultaneous injection is performed in each layer of the ground in the embodiment of FIG.

  A plurality of injection pipes 2 are built in the hole 1 and a columnar permeation source 4 is provided at the tip of each injection pipe 2. The structure of the columnar permeation source 4 is, for example, a structure in which the tip of the injection tube 2 is closed, one or a plurality of injection material discharge ports are formed on the side of the tip, a check valve is provided, and a columnar space water guide member is provided around the check valve Are attached to each.

  What is necessary is just to form a water-permeable coating in the fixed range of the pipe-axis direction including the part which has an injection material discharge port of the injection pipe outer peripheral part. In this case, it is desirable that the material has a certain thickness, is a net or sponge, and is formed from a material having a high permeability and elasticity into a cylindrical shape or a belt shape. Materials, various drain materials, tubes having a plurality of injection material discharge ports and injection material discharge slits, nets or baskets made of bags or resin fibers, and synthetic resin tape, etc. Can do.

  In addition, if one or more discharge ports are provided at the tip of the injection pipe and a covering material that acts as a check valve is provided on the discharge port, the ground injection material that has come out of the discharge port will have a columnar sand column in the axial direction. Or flow into the surrounding ground and then penetrate into the surrounding ground and penetrate into the column.

  The tip of each injection tube 2 configured in this way is arranged so as to be positioned at a predetermined interval in the depth direction of the drilling hole 1. A filter layer S filled with columnar sand or the like is formed between the hole wall of the hole 1 and each injection pipe 2.

  In such a configuration, the filter layer S constitutes a double columnar permeation source, and the injection material is injected into the plurality of injection pipes 2 at the same time, whereby the injection material is injected into the plurality of injection stages A, B, C, and D. Can be injected at the same time.

  FIG. 5 is a vertical sectional view schematically showing the case where the injection is performed on a specific layer of the ground.

  According to the present invention, the seal-packer layer BP formed by filling the columnar filter layer S with sand and bentonite pellets in the hole 1 is formed in a mutual layer, and the specific columnar shape is formed from the discharge port provided on the side surface of the injection pipe 2. The ground injection material for ground improvement is discharged to the filter layer S, the filter layer S acts as a columnar penetration source, and the ground injection is performed from the hole wall of the drilling hole 1 to the specific ground layer.

  FIG. 5 (a) shows a case where injection is performed simultaneously on the upper and lower two layers, and FIG. 5 (b) shows a case where injection is performed only on the upper layer, and the filter layer S acts as a columnar penetration source. The injection material can be uniformly infiltrated into the surrounding ground.

  FIG. 6 is a vertical sectional view schematically showing a case where construction is performed by applying the double packer method to the present invention.

  In this example, the injection tube 2 includes an injection outer tube 2a having injection material discharge ports 5b at a plurality of locations in the tube axis direction, and an injection inner tube 2b installed in the injection outer tube 2a. The ground injection material discharged into the outer tube 2a is discharged from the injection material discharge port 5a of the injection outer tube 2a, and from the hole wall of the drilling hole 1 through the columnar filter layer S whose upper and lower portions are constrained by the seal packer layer BP. It is configured to penetrate into the ground.

  The injection inner tube 2b is provided with a double packer 6 above and below the discharge port 5b at the tip, and is injected from one or a plurality of discharge ports 5b having a check valve of the injection outer tube 2a located between the upper and lower double packers 6. The material is injected into the ground through the filter layer S.

  Also in this case, the sand filter layer S acts as a homogeneous and highly water-permeable columnar penetration source, and allows the ground injection material to efficiently penetrate into the required location in the ground with large discharge and low pressure between soil particles. be able to.

  FIG. 7 schematically shows an apparatus configuration in the case of performing multipoint simultaneous injection for the ground improvement method corresponding to FIG.

  That is, the injection material can be simultaneously injected into a plurality of injection stages A, B, C, and D at a plurality of injection points. In the figure, a plurality of injection pipes 2 of the ground injection device shown in FIGS. 3 and 4 are built in each drilling hole 1 formed at each of a plurality of injection points.

  The tip of each injection tube 2 is arranged so as to be positioned at a predetermined interval in the depth direction of the hole 1. Further, a columnar filter layer S made of sand and a seal packer layer BP filled with bentonite pellets are formed between the hole wall of the drilling hole 1 and each injection pipe 2, and a seal made of cement bentonite is formed at the top. The material CB is filled.

  Further, other configurations such as the provision of an injection material storage tank 10, a conduit 11, a unit pump 12, a flow rate pressure detector 13 and the like are basically the same as those in the case of multipoint injection in FIG.

  Then, by simultaneously or selectively injecting the injection material into the injection tube 2 at each injection point, the injection material is simultaneously injected into the ground of the plurality of injection stages A, B, C, D at the plurality of injection points. Can do.

  FIG. 8 is also configured by the multipoint injection method so that the injection material for ground improvement can be sequentially or simultaneously injected into the ground of the injection stages A, B, C, and D at a plurality of depths at a plurality of injection points. Fig. 6 schematically shows another embodiment of the ground injection device. This example is a case where construction is performed by applying a double packer method using an injection tube 2 having an injection outer tube 2a and an injection inner tube 2b as shown in FIG.

  In the drawing, an injection outer tube 2 is built in each hole 1 formed at each of a plurality of injection points. Also, an injection inner tube lifting device 18 for changing the injection stage by moving the injection inner tube 2b up and down and an injection stage management device 19 for managing the injection stage of the injection inner tube 2b are respectively attached.

  Although not shown in FIG. 8, the tip of each injection outer tube 2 a is closed, a plurality of injection material discharge ports 5 are formed on its side, and a check valve is attached to each discharge port 5. The structure in which the upper and lower portions are constrained by the seal packer layer BP and penetrated from the hole wall of the hole 1 into the ground is the same as in the case of FIG.

  Moreover, the point which is equipped with the injection material storage tank 10, the conduit | pipe 11, the unit pump 12, the flow volume pressure detector 13, etc. is the same as that of embodiment of FIG. 2, FIG.

  In such a configuration, when a flow rate / and / or pressure data signal from the flow rate pressure detector 13 is transmitted to the central control device 17, the injection material in the storage tank 10 is arbitrarily changed by the operation of each unit pump 12. It is pumped to each injection inner tube 2b at the injection speed, injection pressure and injection amount.

  Then, at a plurality of injection points, the injection material is discharged from the plurality of injection material discharge ports 5 of each injection outer tube 2a into the plurality of 7 functioning as columnar penetration sources, and further from the columnar filter layer S at each injection point. It is infused simultaneously into the surrounding ground.

  At this time, the injection inner tube 2b at each injection point is operated by the injection inner tube lifting / lowering device 18 in accordance with an instruction from the central control device 17, and the injection inner tube 2b rises in the injection outer tube 2a. The injection material can be sequentially injected into the ground of each of the injection stages A, B, C, and D at a plurality of injection points.

  Each of the unit pumps 12 can be operated by a drive source 16 such as a motor. Further, each drive source 16 can be operated by a rotational speed transmission 15 such as an inverter controlled by a centralized management device 17.

  Therefore, according to this embodiment, it is possible to configure as a single united infusion device which is composed of a large number of unit pumps 12 and has a small capacity as a whole and is compact.

〔Demonstration experiment〕
In order to confirm the state of penetration according to the present invention, a demonstration experiment was conducted using an aqueous solution in which lithium chloride was dissolved as an injection solution (tracer).

  FIG. 9 shows a soil columnar figure and a standard cross section of an injection test hole and an observation hole (observation well). FIG. 10 shows an injection test hole I, observation holes (observation wells) W1 to W4, and confirmation holes (boring). It is a plane arrangement drawing of B1-B4.

  As for the injection test hole I, as shown on the left side of FIG. 9, the casing is drilled to a depth of 3.5 m from the ground surface reaching the fine sandstone layer in the soil columnar diagram, and the sand (gravel) layer in the soil columnar diagram The longer injection tube (200 mm column penetration source is formed at the discharge port) that reaches the diameter of the column and the column filter layer of dredged sand (No. 3) is formed to a thickness of 900 mm between the drilling wall, A 200 mm thick seal packer layer is formed on the bentonite pellets, and the shorter injection pipe (the discharge port is a column penetration source) that reaches the organic silt layer in the soil columnar diagram is installed. A columnar filter layer of cinnabar sand (No. 3) is formed to a thickness of 900 mm between them, a seal packer layer of 300 mm thickness is formed with bentonite pellets thereon, and cement bentonite is further filled thereon. And a depth corresponding to the organic clay layers and modified soil layer sealed restrained in soil histogram by a sealing member made.

  An aqueous solution in which lithium chloride was dissolved was used as an injection solution (tracer). The dilution rate of lithium chloride was 200 mg / l (ppm).

  The observation holes (observation wells) W1 to W4 are the same as in the case of the injection test hole I as shown on the right side of FIG. 9 (however, a seal packer layer made of bentonite pellets is also formed in the lowermost fine sandstone layer portion). A short 500 mm long strainer tube that observes the groundwater in the sand (gravel) layer and the upper groundwater. A strainer tube having a length of 500 mm provided at the tip of the slab was configured to observe groundwater in the organic silt layer.

  About confirmation hole (boring) B1-B4, (phi) 86mm core collection was performed and the soil data were analyzed.

  For the analysis of lithium, the soil samples were prepared by applying the test solution according to Ministry of the Environment Notification No. 19 (2003) and measured by flame atomic absorption spectrometry. Groundwater was measured by flame atomic absorption.

  Table 1 summarizes the lithium content at each depth in the confirmation holes B1 to B4 in this test, and Table 2 summarizes the lithium content at each depth at the upper and lower portions of the observation holes W1 to W4.

  In addition, since lithium chloride does not exist in soil in a natural state, it is suitable as a tracer as described above, and since the solution is almost neutral, it has little influence on the soil and ground injection material.

  In addition to the previous penetration confirmation test, in the ground improvement method according to the present invention, lithium chloride is added to solidified injection materials such as silica-based grout materials and plastic grout materials, and microbubbles for ground improvement. It can also be used for confirmation of penetration.

S ... Filter layer (sand),
BP ... Seal packer layer (bentonite pellet),
CB ... Sealing material (cement bentonite),
1 ... drilling,
2 ... Injection tube,
2a ... outer pipe,
2b ... inner pipe,
3 ... casing,
4 ... Columnar penetration source,
5 ... discharge port,
10: Injection material storage tank,
11 ... Conduit,
12 ... Unit pump,
13. Flow rate pressure detector,
14 ... Check valve,
15 ... rotational speed transmission,
16 ... drive source,
17 ... Centralized management device,
18 ... Inner tube lifting device,
19 ... Injection stage management device

Claims (13)

Excavating the ground using a casing and forming a hole in the ground;
Installing an injection tube having an injection material discharge port in one or a plurality of locations in the tube axis direction in the drilling hole;
A step of forming a filter layer mainly composed of sand by filling the sand up from the position of the injection material discharge port between the outer periphery of the injection pipe and the drilling wall of the drilling hole while pulling up the casing; ,
Filling the sealing material above the filter layer between the outer periphery of the injection pipe and the drilling wall of the drilling hole while pulling up the casing;
And having a step of discharging the ground injection material of solidity or microbubbles for ground improvement from the injection material discharge port of the injection pipe,
A ground improvement construction method characterized by allowing the ground injection material discharged from the injection material discharge port to permeate into the ground from the hole wall through the filter layer whose upper portion is constrained by the sealing material. The ground improvement construction method according to claim 1 , wherein the sealing material is cement bentonite. 3. The ground improvement method according to claim 1 or 2 , wherein the injection tube is formed by bundling a plurality of injection capillaries having injection material discharge ports at one or a plurality of locations in the tube axis direction, and the discharge ports of the injection tube have different heights. A ground improvement method characterized by being a bundled injection capillary tube. The ground improvement construction method according to claim 1 or 2 , wherein the injection pipe includes an injection outer pipe having an injection material discharge port at one or a plurality of places in the pipe axis direction, and an injection inner pipe installed in the injection outer pipe. The hole injection wall through the filter layer whose upper part is constrained by the sealing material by discharging the ground injection material discharged from the injection inner tube into the injection outer tube from the injection material discharge port of the injection outer tube A ground improvement method characterized by infiltrating from the ground into the ground. Excavating the ground using a casing and forming a hole in the ground;
Installing an injection tube having an injection material discharge port in one or a plurality of locations in the tube axis direction in the drilling hole;
A step of forming a filter layer mainly composed of sand by filling the sand up to a position below the position of the injection material discharge port between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole while pulling up the casing; ,
Forming a seal packer layer containing bentonite above the filter layer between the outer periphery of the injection tube and the drilling wall of the drilling hole while pulling up the casing;
When the injection material discharge port of the injection pipe is further above the seal packer layer, the injection material between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole is raised while the casing is pulled up. A step of forming a filter layer mainly composed of sand by filling sand below the discharge port position, and the filter between the outer peripheral portion of the injection pipe and the drilling wall of the drilling hole while pulling up the casing A step of forming a seal packer layer containing bentonite above the layer, a step of repeating one or more times,
And having a step of discharging the ground injection material of solidity or microbubbles for ground improvement from the injection material discharge port of the injection pipe,
The ground, wherein the ground injection material discharged from the injection material discharge port is permeated into the ground from the hole wall through the filter layer in which an upper portion or an upper portion and a lower portion are constrained by the seal packer layer. Improvement method. The ground improvement construction method according to claim 5 , wherein the seal packer layer is made of bentonite pellets. 7. The ground improvement method according to claim 5 or 6 , wherein the injection tube is formed by bundling a plurality of injection capillaries having injection material discharge ports at one or a plurality of locations in the tube axis direction, and the discharge ports of the injection tube have different heights. A ground improvement construction method comprising a bundle injection capillary provided with a filter layer mainly composed of sand around a discharge port of the bundle injection capillary. The ground improvement construction method according to claim 5 or 6 , wherein the injection pipe includes an injection outer pipe having an injection material discharge port at one or a plurality of places in the pipe axis direction, and an injection inner pipe installed in the injection outer pipe. The filter in which the ground injection material discharged from the injection inner tube into the injection outer tube is discharged from the injection material discharge port of the injection outer tube, and the upper part, or the upper part and the lower part are restrained by the seal packer layer. A ground improvement construction method characterized in that it penetrates into the ground from the drilling wall through a layer. The soil purification construction method according to any one of claims 1 to 8, wherein an injection pipe in which a columnar infiltration source is provided at the injection material discharge port is used as the injection pipe. The ground improvement construction method according to any one of claims 1 to 9 , wherein the sand-based filter layer has a columnar shape whose height is larger than the diameter. The ground improvement construction method according to any one of claims 1 to 10 , wherein the caking ground injection material is a silica grout material. The ground improvement construction method according to any one of claims 1 to 10 , wherein the caking ground injection material is a plastic grout material. The ground improvement construction method according to any one of claims 1 to 12 , wherein lithium chloride as a tracer is added to the ground injection material.