JP2022046072A - Multistage simultaneous injection device - Google Patents

Abstract

To provided a multistage simultaneous injection device and a method thereof allowing infiltration of grout to be finely carried out under lower pressure by injecting the grout with low outlet amount in the spaces between sandy soil particles.SOLUTION: A multistage simultaneous injection device 1 is provided with: an outer pipe 2 provided with outer pipe nozzles 3 to 3''' arranged with the number of four stages or more in a depth direction corresponding to an injection step injecting grout; a four cylinder four series injection pump 4; and an air generator 9 supplying gas by pressure, wherein four outlet ports 5 to 5''' provided in the injection pump 4 are connected to injection pipes 7 to 7''' having outlet holes 8 to 8''' placed in four stages in a depth direction corresponding to an injection step, the air generator 9 is connected to five air packer members 12 to 12'''' sealing gaps between upper parts and lower parts to allow gas to be supplies by pressure through communicated air pipes 11, of which one of air pipes 11 has an inner pipe configured to place four injection pipes 7 to 7''' therearound, and the inner pipe is inserted into the outer pipe 2 and configured to be liftable in the outer pipe 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a strainer method for infiltrating grout into soft ground, especially in the gaps between sandy soil particles to stop water and strengthen the ground. It relates to a multi-stage simultaneous injection device that simultaneously injects grout into four stages and a multi-stage simultaneous injection method using the same.

Conventionally, a chemical solution (hereinafter referred to as grout) injection method has been widely used for the purpose of stopping water in soft ground and strengthening the ground. In particular, in recent years, due to the frequent occurrence of earthquakes and natural disasters, measures against liquefaction or earthquake resistance of existing structures are required.

These target grounds are sandy soils that have been deposited over many years in rivers and seaside areas, because the soft alluvial sandy soils are formed in layers by sedimentation during the sedimentation process. Is not uniform, and is often composed of sand particles with a coarse bottom and fine top.

In addition, sandy soil is a complex and diverse layered ground such as cohesive soil and gravel. For this reason, the permeability (permeability coefficient) is also significantly different, and the permeability coefficient is larger in the horizontal direction than in the vertical direction, and the stratum boundary also tends to be larger.

The strainer method is mainly used as a method of injecting grout into such a non-uniform sandy soil layer under groundwater. The strainer method includes a single tube strainer method (see Non-Patent Document 1, P131) and a double packer method in the order of development. Typical examples of the double packer method include a soletanche method and a sleeve method (see Non-Patent Document 1, P132 to 133). Since then, a super-multi-point injection method (see Patent Document 2 and Non-Patent Document 2) has been developed.

[Single tube strainer method]
The single-tube strainer method was first developed in Japan. This single-tube strainer method consists of two steps: installation of an injection tube in the first step and injection in the second step. In the first step, an injection pipe provided with a large number of surrounding injection holes, which is a gas pipe with a sharp tip, is driven into the target ground and installed. In the second step, the injection tube is filled with a solution-type drug solution in advance to gel the gap between the injection tube and the ground and the inside of the injection tube, and then the inside of the injection tube within the injection range (injection action length is about 1 m). Drain by washing with water to secure the injection hole.

Next, when the grout is injected with one pump with one hose, due to the difference in the ground (ground resistance pressure), the injected grout will be placed in the injection hole where no pressure is applied even if the pressure difference is extremely small. It penetrates a lot, and on the contrary, it becomes difficult to penetrate into the injection hole where pressure is applied.

This tendency expands over time, and if the injection is continued for a longer time than the gel time, the pores are finally closed in combination with the gelation. On the contrary, the number of holes to be injected is several, resulting in non-uniform penetration. For this reason, the single-tube strainer method has a fatal defect that it cannot stop water or strengthen the ground, and is not used at all at present.

[Double packer method]
After that, the double packer method (also known as the Soletanche method), the sleeve injection method, and the double strainer method, which were introduced from France, were developed and are now the mainstream. In addition, this double packer method belongs to the double pipe strainer method in terms of classification.

This double packer method consists of two steps: installation of an injection pipe in the first step and grout injection in the second step. In the first step, a hole is drilled to set a casing pipe, and the pipe is filled with seal grout (mainly CB liquid). After that, the injection pipe (outer pipe) is inserted, and the casing pipe is pulled out before the seal grout is cured. Then, after the seal grout is cured, the seal grout cured by water pressure is cracked to secure the grout flow path.

In the second step, a double packer device is connected to the injection pipe (inner pipe) in the injection pipe (outer pipe), and packers (double packers) are formed and fixed above and below the outer pipe nozzle at a predetermined position, and grout is performed. Inject. The double packer device is then pulled up to the upper step and similarly infused with grout. This is repeated, and after the injection is completed, the double packer device is collected. This double packer device corresponds to the inner pipe.

This double packer method can inject low discharge and low pressure, but it takes a long time to inject because only one point is injected per injection method. Therefore, even if the discharge amount of grout is as large as 8 to 10 L per minute, there is a problem in construction that the work efficiency is inferior, and there is a problem that it is not possible to efficiently inject at low pressure with low discharge.

In the double packer method, it is technically possible to connect a plurality of double packer devices (for example, 3 to 4 points) in a plurality of stages in one injection method. However, since there is only one injection pipe, as described in the single-tube strainer method described above, it is not possible to uniformly discharge from each injection hole due to the difference in ground resistance pressure at the time of injection, so this is currently practiced. not.

[Ultra multi-point injection method]
The ultra-multi-point injection method consists of two steps: installation of an injection pipe in the first step and grout injection in the second step. In the first step, the casing is installed in a predetermined position, and the seal grout is filled therein. Then, when the seal grout is not yet solidified, insert the injection pipe, pull out the casing pipe, and fix the injection pipe. This injection pipe is used as a bundle at a plurality of multi-stage positions (injection steps), and is used as a device for simultaneously injecting into a plurality of (usually 3 to 5 points) per injection work.

In the second step, after cracking the seal grout, grout is multi-staged from one unit (connecting a large-capacity multi-unit heavy-duty pump to multiple small-capacity pumps) from each pump, injection hose, and nozzle tip at the tip of the injection pump. Simultaneously inject into (point). For this reason, injection from one point can be finely permeated at low pressure with a low discharge rate (about 3 to 5 L / min), and one injection work can be completed in one injection, improving work efficiency. There is an advantage to do.

On the other hand, technically, unlike the double packer method, the injection pipe (inner pipe) is not used, and the packer is not used, and the injection pipe is installed in the center of the seal grout to ensure the packer effect. There is a drawback that it is difficult to demonstrate.

Further, for example, when five pipes are installed for each step, the position of the uppermost injection pipe overlaps with the other four injection pipes, and the grout injected from the nozzle is cracked (flow path of the crack). There is also the difficulty that it is difficult to inject evenly into the ground through the entire surface.

Further, in terms of construction, the injection pipe and the tip nozzle after injection are fixed to the seal grout and cannot be recovered, and it is also a problem that they are left as they are. Another drawback is that the ultra-multi-point injection device used in the ultra-multi-point injection method is expensive.

The double packer method and the ultra-multi-point injection method described above have advantages and disadvantages, respectively, and a method that eliminates these disadvantages and incorporates (or utilizes) the advantages is desired. That is, using a multi-stage packer device in which packers are provided above and below multiple injection holes in the injection pipe (outer pipe, strainer pipe) for one injection, multi-stage simultaneous injection is possible and grout injection is performed at low pressure with a low discharge amount. A possible injection method is desired. In addition to that, an injection method capable of recovering the inner tube (multi-stage simultaneous injection device) after the completion of injection is also desired.

JP-A-2015-36503 Japanese Unexamined Patent Publication No. 11-81296

Kazuto Kusano, "Handbook of Chemical Injection Method", Yoshii Shoten, July 5, 1983, P131-135 Ryozo Yonekura and Shunsuke Shimada, "Design and Construction of Permanent Grout Main Injection Method", Modern Science Co., Ltd., October 31, 2016, pp. 133-135

Therefore, the present invention has been devised to solve the above-mentioned problems, and the purpose thereof is to inject grout into the gaps between sandy soil particles at a low discharge rate (1 to 8 L / min). It is an object of the present invention to provide a multi-stage simultaneous injection method capable of finely infiltrating with low pressure.

The multi-stage simultaneous injection device according to the first invention is a multi-stage simultaneous injection device for simultaneously infiltrating a grout into a plurality of stages in the depth direction in a sandy soil particle gap to stop water and strengthen the ground, and is an injection for injecting the grout. It is equipped with an outer pipe provided with four or more outer pipe nozzles in the depth direction according to the step, a four-cylinder four-series injection pump, and an air generator that pumps gas, and the injection pump has four. It has a discharge port, and these four discharge ports are connected to an injection pipe having four discharge holes provided in the depth direction corresponding to the injection step, and the air generator moves between the upper and lower parts of the injection step. An inner pipe bundled by arranging four injection pipes around one air pipe, which is connected so that gas can be pumped to each air packer member through an air pipe communicating with five air packer members to be closed. The inner pipe is inserted into the outer pipe and is configured to be able to move up and down with respect to the outer pipe.

The multi-stage simultaneous injection device according to the second invention is characterized in that, in the first invention, the grout injected by the injection pump is a one-component grout having a gelation time of 30 minutes or more.

In the multi-stage simultaneous injection method according to the third invention, the multi-stage simultaneous injection device according to claim 1 or 2 is used to simultaneously infiltrate the grout into the sandy soil particle gaps in a plurality of stages in the depth direction to stop water or ground. This is a multi-stage simultaneous injection method for strengthening, in which gas is sent from the air generator to the air packer member via the air pipe, each of the five air packer members is inflated, and the space between the upper and lower parts of the injection step is closed. An air packer expansion step is performed, and then the grout is squeezed from the discharge hole of the injection pipe installed in four stages in the depth direction according to the injection step at a low discharge rate of 1 to 8 L / min using the injection pump. In addition to performing the grout injection step of injecting four stages at the same time, the inner pipe is pulled up to the upper injection step, and the air packer expansion step and the grout injection step are repeated to inject grout in every four injection steps. It is a feature.

According to the first to third inventions, due to the low pressure and the low discharge amount, not only the soil particle gap can be finely infiltrated instead of split infiltration, but also the injection time can be increased because it can be simultaneously injected into multiple stages (4 points). It can be shortened to save construction labor and reduce construction costs. Moreover, according to the first to third inventions, unlike the super multi-point injection method, the inner tube can be easily recovered after the grout injection is completed.

In particular, according to the second invention, since it is a one-component grout, it has extremely excellent permeability and can be finely penetrated.

FIG. 1 is a schematic cross-sectional view schematically showing a configuration of a multi-stage simultaneous injection device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line of FIG. FIG. 3 is a cross-sectional view taken along the line of FIG. FIG. 4 is a cross-sectional view taken along the line Ha-ha of FIG. FIG. 5 is a process explanatory view showing a construction procedure of the multi-stage simultaneous injection method according to the embodiment of the present invention. 6A and 6B are plan views schematically showing a grout consolidated body, in which FIG. 6A is a grout consolidated body formed in Example 1, and FIG. 6B is a grout consolidated body formed in Comparative Example 1. be. 7A and 7B are side views schematically showing a grout consolidated body, in which FIG. 7A is a grout consolidated body formed in Example 1, and FIG. 7B is a grout consolidated body formed in Comparative Example 1. be. 8A and 8B are horizontal cross-sectional views schematically showing a grout consolidated body, in which FIG. 8A is a grout consolidated body formed in Example 1, and FIG. 8B is a grout consolidated body formed in Comparative Example 1. Is.

Hereinafter, the multi-stage simultaneous injection device according to the embodiment of the present invention and the multi-stage simultaneous injection method using the same will be described with reference to the drawings.

<Multi-stage simultaneous injection device>
First, the multi-stage simultaneous injection device 1 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view schematically showing the configuration of the multi-stage simultaneous injection device 1 according to the embodiment of the present invention.

As shown in FIG. 1, the multi-stage simultaneous injection device 1 according to the embodiment of the present invention includes an outer pipe 2 which is a PVC pipe, an injection pump 4 which pumps grout through the outer pipe 2, and the like.

(Outer pipe)
The outer pipe 2 is installed in the same manner as the above-mentioned double packer method or super multi-point injection method (there is no outer pipe 2 and the hose is inserted in a bundle). That is, a casing pipe (not shown) is installed in the ground by drilling a hole, and the casing pipe is filled with a seal grout 14 mainly composed of a CB liquid (cement bentonite liquid). After that, the outer pipe 2 which is an injection pipe is inserted, and before the seal grout 14 is hardened, the casing pipe is pulled out, so that the outer pipe 2 is solidified and fixed by the seal grout 14. Of course, the seal grout 14 is cracked by water pressure to secure a grout flow path.

The outer tube 2 is provided with outer tube nozzles 3 to 3'''in a plurality of stages in the vertical direction (depth direction) according to the injection step for injecting grout, and these outer tube nozzles 3 to 3'''. Through'', the grout described later is injected into the ground made of sandy soil in order to stop water in the soft ground and strengthen the ground.

(Infusion pump)
This injection pump 4 is a 4-cylinder 4-series plunger type that is an improvement of the 4-cylinder 2-series plunger type (piston type) multi-cylinder pump used for grout pumping and has a discharge port for each cylinder. It is a multi-cylinder pump.

The injection pump 4 has four discharge ports 5 to 5''', and each of the four discharge ports 5 to 5'''' has four resin injection hoses 6 to 6''''. It is connected. Further, metal injection pipes 7 to 7 ″ are connected to these four injection hoses 6 to 6 ″. The tip of the injection pipe 7 to 7'''is a discharge hole 8 to 8''', and the grout pumped by the injection pump 4 is discharged from these discharge holes 8 to 8''' to crack the seal grout 14. It is injected into the ground through.

These discharge holes 8 to 8'''and outer tube nozzles 3 to 3'' are in the injection step depth direction (vertical direction) for injecting grout, similarly to the above-mentioned outer tube nozzles 3 to 3'''. It is installed in 4 stages. That is, the installation depth (height) of each stage of the discharge holes 8 to 8'''and the outer pipe nozzles 3 to 3'' corresponds to the grout injection step of the multi-stage simultaneous injection method, and is above and below these. The interval is usually about 30 cm to 50 cm.

(Air generator)
Further, the multi-stage simultaneous injection device 1 includes an air generator 9 including a compressor or the like. A resin air hose 10 is connected to the air generator 9, and an air pipe 11 which is a metal pipe is connected to the air hose 10. The air pipe 11 is provided with five air discharge ports so as to sandwich the discharge holes 8 to 8'', which are the injection steps of each stage, and the air pipe 11 is provided to a position deeper than the discharge holes 8'''' in the lowermost stage. Has reached.

(Air packer member)
Five air packer members 12 are mounted on these five air discharge ports. The air packer member 12 is made of a stretchable material such as a rubber elastic body, expands when gas is sent from the air generator 9, closes between the upper and lower parts of the injection step, and the grout to be injected is injected downward. It has a function to prevent escape to the step.

Nitrogen gas is adopted as the gas for inflating the air packer member 12 according to the present embodiment. Of course, it goes without saying that other gases such as air may be used. The air packer member 12 closes the upper and lower sides of the outer pipe nozzles 3 to 3 ″ of each of the four stages in the outer pipe 2, and ensures grout from the outer pipe nozzles 3 to 3''''. It is possible to penetrate the gap.

(Inner tube)
FIG. 2 is a cross-sectional view taken along the line of FIG. 1 and FIG. 3 is a cross-sectional view taken along the line Loro of FIG.
Further, FIG. 4 is a cross-sectional view taken along the line Ha-ha of FIG. As shown in FIGS. 2 to 4, the four injection pipes 7 to 7'' and the air pipe 11 are arranged in advance with the air pipe 11 as the center and four injection pipes 7 to 7''' around the air pipe 11. It is fixed in a bundle. In this way, the inner pipe 15 (advanced device, drawing) is a bundle in which four injection pipes 7 to 7'''are arranged around the air pipe 11 in which the above-mentioned air packer member 12 is attached. It is called 1).

As shown in FIGS. 2 to 4, since the inner pipe 15 (the upper part can be wound with an injection hose and an air hose) is bundled together, the inside of the outer pipe 2 is the injection pipe 7 to 7'''and the air pipe 11. The space for grouting is secured without being filled with such things, and the grout can be freely injected from the outer tube nozzles 3 to 3'''. This point is different from the super multi-point construction method described in the background technology. Further, as will be described later, the inner pipe 15 is inserted into the outer pipe 2 and is configured to be able to move up and down with respect to the outer pipe 2 by the elevator 18 (see FIG. 5).

The seal grout 14 shown in FIG. 1 is injected and filled in the gap between the outer pipe 2 and the ground (ground) when the outer pipe 2 is installed, and will be described in detail in the construction procedure described later.

<Multi-stage simultaneous injection method>
Next, the multi-stage simultaneous injection method according to the embodiment of the present invention will be described. First, the discharge amount and the injection pressure will be described.

[Discharge volume and injection pressure]
As described above, the injection pump 4 of the multi-stage simultaneous injection device 1 according to the embodiment of the present invention has multiple stages of grout from four discharge ports 5 to 5'''independent of one pump (4 points: deep). Inject simultaneously into 4 different injection steps). For this reason, the injection for each stage enables an extremely small discharge amount (injection rate) of 1 to 8 L per minute, and as a result, fine penetration injection can be performed in the soil particle gap at low pressure, and the injection time is long. It has the advantage of being significantly shortened.

Specifically, assuming that the discharge amount of the pump is 12 L / min, the discharge amount of each stage (4 points) is 12 × 1/4 = 3 L, which is an extremely small amount of discharge, so the injection pressure is also extremely low. Penetration injection is possible with.

Further, assuming that the discharge amount of the pump is 8 L per minute, the discharge amount of each stage is 8 × 1/4 = 2 L. This is a low pressure that cannot be accurately discharged by a normal 4-cylinder double pump (two-component pump set at 8 to 16 L / min).

For example, when a soft alluvial fine sand soil (N value of about 10 and a hydraulic conductivity of ^10-3 [cm / sec]) is injected at a discharge rate of 8 L (double packer) per minute, the pressure is 0.3 [MPa]. It has been demonstrated that a high value is required (see Table 1).

On the other hand, as will be described later, it has been confirmed that in the multi-stage simultaneous injection method according to the present embodiment, injection can be performed at a very low pressure of 0.15 [MPa] with a low discharge amount of 3 L / min (Table). See 1). That is, in order to infiltrate the grout into the soil particle gaps of the sandy soil which is the target of the multi-stage simultaneous injection method according to the present embodiment, an injection pressure exceeding the resistance pressure (ground resistance pressure) for accepting the grout is required. This resistance pressure is proportional to the discharge amount (the capacity of the grout per injection time), and if the discharge amount is large, a high pressure is applied, and it cannot penetrate into the soil particle gap, expanding the ground and splitting (pulse). It penetrates while infiltrating into the shape) and cannot penetrate uniformly. This phenomenon is called split osmosis injection.

On the other hand, the smaller the discharge amount, the slower and finer the penetration into the soil particle gap with a smaller pressure. That is, the smaller the discharge amount, the lower the pressure, which is ideal.

However, in consideration of workability, a discharge amount of a certain level or more is required, and in consideration of the performance of a practical injection pump, in the multi-stage simultaneous injection method according to the present embodiment, the discharge amount is preferably , The lower limit is 2 L / min. Further, the upper limit of the discharge amount is preferably 5 L / min, which enables fine penetration. That is, the discharge amount in the multi-stage simultaneous injection method according to the present embodiment is in the range of 2 to 5 L / min per injection point (8 to 20 L / min in total at the four points).

[Construction procedure]
Hereinafter, the construction procedure of the multi-stage simultaneous injection method according to the embodiment of the present invention will be described with reference to FIG. An example will be described in which the above-mentioned multi-stage simultaneous injection device 1 is used to inject into a ground made of sandy soil in order to stop water in soft ground and strengthen the ground. FIG. 5 is a process explanatory view showing a construction procedure of the multi-stage simultaneous injection method according to the present embodiment.

The multi-stage simultaneous injection method according to the embodiment of the present invention is the same as the first step of the double packer method described in the background technique until the outer pipe 2 is installed, and the difference is that the multi-stage simultaneous injection method is performed. The point is that the inner tube 15 of the device 1 is used.

(1. Drilling and casing pipe installation)
As shown in FIG. 5 (1), in the multi-stage simultaneous injection method according to the present embodiment, first, (1) the ground is drilled to a predetermined depth by a boring machine to provide a standing hole, and a casing pipe (shown) is provided therein. Perform the drilling and casing pipe installation process.

(2. Seal grout filling)
Next, as shown in FIG. 5 (2), in the multi-stage simultaneous injection method according to the present embodiment, (2) the seal grout 14 mainly composed of CB liquid (cement bentonite liquid) is injected and filled into the casing. Perform the seal grout filling process.

(3. Installation of outer pipe)
Next, as shown in FIG. 5 (3), in the multi-stage simultaneous injection method according to the present embodiment, after the outer pipe 2 is inserted before the seal grout 14 filled in the previous step is cured, the casing (3) The outer pipe installation step of pulling out the pipe, hardening the seal grout 14 and installing the outer pipe 2 is performed.

Further, as described above, the outer pipe 2 is provided with a plurality of outer pipe nozzles 3 to 3 ″ around the positions of the discharge holes 8 to 8 ″ of the inner pipe 15. In this step, after the seal grout 14 is hardened, water is pumped from the outer pipe nozzles 3 to 3'''via the injection hose 6 to 6'' and the injection pipe 7 to 7''', and water pressure is applied. Cracking (cracking) is generated and the grout injection flow path is secured.

The steps from (1. drilling / casing pipe installation) to (3. outer pipe installation) are the same as the double packer method described in the background technique.

(4-1. Air packer expansion process)
Next, as shown in FIG. 5 (4-1), in the multi-stage simultaneous injection method according to the present embodiment, as described above, four injections are made around the air pipe 11 in which the air packer member 12 is attached. Insert the inner pipe 15 in which the pipes 7 to 7'''are arranged and bundled.

Then, as shown in FIG. 5 (4-1), in the multi-stage simultaneous injection method according to the present embodiment, nitrogen is sent as a gas from the air generator 9 via the air hose 10, the air pipe 11, and the air flow path 13, and 5 An air packer expansion step of inflating each of the air packer members 12 to 12'''' at each location to close the space between the upper and lower parts of the injection step is performed (see also FIGS. 2 to 4).

(4-2. Grout injection process)
After that, as shown in FIG. 5 (4-2), in the multi-stage simultaneous injection method according to the present embodiment, the injection pump 4 is used from the discharge holes 8 to 8'''' of the injection pipes 7 to 7''. A grout injection step of injecting a one-component grout is performed.

Specifically, in the injection pump 4, which is a 4-cylinder 4-unit type plunger type multi-cylinder pump, as described in [Discharge amount and injection pressure], injection for each stage is 1 to 8 L per minute. , Preferably, inject with a very small discharge amount of 2 to 5 L. Therefore, according to the multi-stage simultaneous injection method according to the present embodiment, it is possible to slowly and finely permeate the one-component grout into the soil particle gaps of the sandy soil with a small pressure, and the uniform grout solidified body 17 (sand gel). ) Can be created to strengthen the ground and stop water (see Fig. 5 (5-1), etc.).

(5. Injection step replacement process)
Next, in the multi-stage simultaneous injection method according to the present embodiment, the air generator 9 is operated to remove nitrogen (gas) from the air packer members 12 to 12'''', and the air packer members 12 to 12''''. Squeeze. Then, as shown in FIG. 5 (5-1), in the multi-stage simultaneous injection method according to the present embodiment, a bundled tip device is used by using an elevator 18 that winds up a wire rope 19 that suspends an inner pipe 15 by a motor. An injection step replacement step is performed in which the inner pipe 15 of the above is pulled up to the upper multi-stage injection step.

Next, as shown in FIG. 5 (5-1), the above-mentioned air packer expansion step is performed. Then, as shown in FIG. 5 (5-2), the grout injection step described above is performed.

In this way, the air packer expansion process and the grout injection process are repeated in sequence, and the process of simultaneously injecting four stages of injection steps is repeated to inject the one-component grout described later into the ground at a predetermined depth (injection work). ) Is completed.

Although the elevator 18 has a configuration in which a wire rope is wound up by a motor is illustrated and illustrated, it is possible to adopt a machine having any configuration as long as it has a mechanism capable of lifting and moving the inner pipes 15 together. Needless to say.

As described above, according to the multi-stage simultaneous injection method according to the present embodiment, by using the multi-stage simultaneous injection device 1 which is a simple facility centered on the 4-cylinder 4-unit injection pump 4, 4 at a time. One-component grout can be injected into the stages (4 points) at the same time with a low discharge amount. Therefore, according to the multi-stage simultaneous injection method according to the present embodiment, not only can the soil particle gaps be finely infiltrated instead of split-penetration injection due to the low pressure and low discharge amount, but also the injection time can be simultaneously injected in multiple stages. It is possible to reduce the construction cost by shortening the construction labor and saving the construction labor. Moreover, after the grout injection is completed, the inner pipe 15 can be pulled up by the elevator 18 and easily collected.

[One-component grout]
Next, the grout to be injected into the ground by the multi-stage simultaneous injection method according to the embodiment of the present invention described above will be described in more detail.

The grout used in the multi-stage simultaneous injection method according to the embodiment of the present invention is premised on pumping through four injection hoses 6 to 6'''and the like using a four-cylinder four-series injection pump 4. Therefore, a one-component grout with a gel time (gelation time) of 30 minutes or more is adopted.

The one-component grout is not particularly limited, but is typically an acidic silica sol solution type (hereinafter, simply referred to as silica sol grout) in which an acid is removed from water glass with an acid, a water glass-ultrafine cement type, or an ultrafine grout. Examples thereof include fine-grained cement-based permeable grout.

Here, the ultrafine particles are composed of particles having a particle diameter of approximately 2.5 μm or less, and are mixed with a plane value of 6,000 [cm ³ / g] or more. In addition, cement-based cements include ordinary Portorant cement, early-strength Portorant cement, ultra-early-strong Portorant cement, moderate-heat Portrant cement, low-heat Portrant cement, and sulfate-resistant Portorant cement. Not only blast furnace cement, silica cement, fly ash cement cement-slag mixed cement are also included. In addition, the cement system shall also include the slag-lime system.

However, as the one-component grout, the silica sol type is most preferable. This silica sol is an acidic silica sol grout with a gel time of 30 minutes or more and a pH of 4 or less, which is obtained by proportionally continuous mixing (silica sol production equipment) of water glass water solution obtained by diluting water glass with water and sulfuric acid (75% industrial one). This is because it has extremely excellent permeability.

[Effect confirmation experiment]
Next, using the above-mentioned multi-stage simultaneous injection device 1, the results of measuring the change in the injection pressure value due to a slight difference in the discharge amount of the grout are shown in Table 1 below, which was executed according to the above-mentioned multi-stage simultaneous injection method. I will explain. In addition, the shape of the grout consolidated body 17 after injection was confirmed, and the permeation form of the grout was confirmed by splitting the grout consolidated body 17 in half.

The injection ground is a soft alluvial fine sand layer 1.5 to 5 m below the surface near the river (N value 5, permeability coefficient 10 ^-3 [cm / sec] order).

The one-component grout used was a silica sol-based solution type, and dilute sulfuric acid was added to 500 L of water glass solution in which 350 L of water was added to 150 L of water glass (SiO ₂ 25.2%, Na ₂ 7.0%, molar ratio 3.72). 17 L (75% for industrial use) was added to produce 1 m ³ of silica sol grout with a silica sol making machine. This silica sol was an acidic solution having a viscosity of 1.8 cP (centipores: mPa · s) and a pH of 3.0, and had a gel time of 10 hours.

For injection, use a 4-cylinder 4-unit injection pump from each outer pipe nozzle (diameter 3 mm, 4 locations) at 4 stages of injection points 2.0 m, 2.5 m, 3.0 m, and 3.5 m below the surface of the earth. Simultaneous injection was performed using.

However, in the injection performed as a comparison, the grout from one of the four discharge ports of the four-cylinder four-unit injection pump is returned to the injection pump, and the grout from the remaining three discharge ports is returned to the injection pump. It was injected into one injection hose at one point 2.0 m below the ground surface.

From Table 1, in the multi-stage simultaneous injection using a 4-cylinder 4-unit injection pump, when injection was performed in Examples 1 to 4 of the 1st to 4th stages (points) of 3 L / min, which was extremely small, the injection started 1 minute. The subsequent injection pressure is 0.05 [MPa], and gradually increases as the injection time (measurement time) elapses, and continues to increase until the end of injection (15 minutes later) without decreasing the injection pressure. , 0.10 to 0.15 [MPa], but it was confirmed that injection was possible at extremely low pressure.

On the other hand, in Comparative Example 1 at 9.0 L / min, which has a large discharge rate, it was as high as 0.20 [MPa] even 1 minute after the start of injection, and increased to 0.25 [MPa] 2.5 minutes later. However, at the end of the injection, the highest injection pressure was shown at 0.30 [MPa]. As a result, it was found that the injection pressure differs greatly between the case where the discharge rate is 3.0 L / min (Examples 1 to 4) and the case where the discharge rate is 9.0 L / min (Comparative Example 1).

Next, the shape and the like of the grout consolidated body will be described with reference to FIGS. 6 to 8. 6A and 6B are plan views schematically showing the grout consolidated body, in which FIG. 6A is the grout consolidated body formed in the above-mentioned Example 1, and FIG. 6B is the grout formed in the above-mentioned Comparative Example 1. It is a consolidated body. Further, FIG. 7 is a side view schematically showing the grout consolidated body, in which (a) is the grout consolidated body formed in the above-mentioned Example 1 and (b) is formed in the above-mentioned Comparative Example 1. It is a grout consolidated body.

One week after the injection, the grout consolidation formed by the above-mentioned multi-stage simultaneous injection was dug up to 2.5 m from the ground surface, and the shape was confirmed. As shown in FIG. 6A, the grout consolidation according to Example 1 was observed. It was confirmed that the body was permeated and consolidated in an almost circular shape (spherical shape) in a plan view. On the other hand, as shown in FIG. 6B, it was confirmed that the consolidated solidified body according to Comparative Example 1 had an elliptical shape elongated in two horizontal directions in a plan view.

Further, as shown in FIG. 7A, in the side view, the grout consolidation body according to the first embodiment has a substantially circular shape, and is infiltrated and consolidated in a spherical shape together with the plan view. Was confirmed. On the other hand, as shown in FIG. 7B, the consolidated solid body according to Comparative Example 1 has an elliptical shape that is elongated in two horizontal directions even in the side view, and is in the horizontal direction together with the plan view. It was confirmed that the length was smaller than the thickness and the shape was flat.

Further, in order to confirm the permeation form of the grout of the grout consolidated body, it was visually confirmed even if it was divided in half at the center of the grout consolidated body, and it is shown in FIG. 8A and 8B are horizontal cross-sectional views schematically showing the grout consolidated body, in which FIG. 8A is the grout consolidated body formed in Example 1 described above, and FIG. 8B is formed in Comparative Example 1 described above. It is a grout consolidated body.

As shown in FIG. 8A, the cross section of the grout consolidated body according to Example 1 showed no trace of split infiltration of the grout. It is considered that this is because the grout was slowly injected at a low discharge rate with a low discharge amount, so that the osmotic solidified body was formed into a spherical shape by gradually expanding the osmosis to the outside while penetrating into the soil particle gap.

Based on this, by half-split visual verification of this grout solidified body, by simultaneous injection in multiple stages at low pressure with the above-mentioned low discharge amount, it is possible to infiltrate finely and inject grout in a short time instead of split infiltration. It was proved that it is an extremely excellent permeation injection type injection method that can be performed.

On the other hand, as shown in FIG. 8 (b), the cross section of the rout consolidated body according to Comparative Example 1 in which the discharge amount per hour was larger than that in the example became white in a streak-like manner centering on the central portion. It was possible to see the traces of splitting invasion, and it was confirmed that the cracks had penetrated into the surrounding area. From this, it can be said that the injection form according to Comparative Example 1 was found to be split permeation.

In short, it can be concluded that the difference between the two injection forms is due to the difference in the grout discharge amount.

The multi-stage simultaneous injection device according to the embodiment of the present invention and the multi-stage simultaneous injection method using the same have been described above. However, the above-mentioned or illustrated embodiments are merely shown as one embodiment embodied in carrying out the present invention, and the technical scope of the present invention is limitedly interpreted by the illustrated embodiments. It should not be.

1: Multi-stage simultaneous injection device 2: Outer pipe 3 to 3''': Outer pipe nozzle 4: Injection pump 5 to 5''': Discharge port 6 to 6''': Injection hose 7 to 7''': Injection Pipe 8-8''': Discharge hole 9; Air generator 10: Air hose 11: Air pipe (inner pipe)
12-12'''': Air packer member 13: Air flow path 14: Seal grout 15: Inner pipe 17: Grout consolidation body 18: Elevator 19: Wire

The multi-stage simultaneous injection device according to the first invention is a multi-stage simultaneous injection device for water stoppage and ground strengthening by simultaneously infiltrating gas in a plurality of stages using a 4-cylinder 4-unit injection pump in the depth direction in the sandy soil particle gap. It is an injection device and includes an outer pipe provided with four or more outer pipe nozzles in the depth direction corresponding to the injection step for injecting grout, and an air generator for pumping gas. The injection pump is 4 It has one discharge port, and these four discharge ports are connected to an injection pipe having four discharge holes provided in the depth direction corresponding to the injection step, and the air generator is located between the upper and lower parts of the injection step. Gas is pumped and connected to each air packer member through an air pipe that communicates with the five air packer members that block the air, and four injection pipes are arranged around one air pipe and fixed in a bundle. It has an inner pipe that is a tip device that can be lifted and moved together and can be fixed to the outer pipe by inflating the air packer member, and the inner pipe is inserted into the outer pipe and into the outer pipe. On the other hand, it is characterized in that it is configured to be able to move up and down.

According to the first invention, due to the low pressure and the low discharge amount, not only the soil particle gap can be finely infiltrated instead of split infiltration, but also the injection time can be shortened because it can be simultaneously injected into multiple stages (4 points). Labor can be saved and construction costs can be reduced. Moreover, according to the first invention, unlike the super-multi-point injection method, the inner tube can be easily recovered after the grout injection is completed.

Claims (3)

It is a multi-stage simultaneous injection device that simultaneously infiltrates grout into the gaps between sandy soil particles in multiple stages in the depth direction to stop water and strengthen the ground.
It is equipped with an outer tube provided with four or more outer tube nozzles in the depth direction according to the injection step for injecting grout, a four-cylinder four-series injection pump, and an air generator that pumps gas.
The injection pump has four discharge ports, and these four discharge ports are connected to an injection pipe having four discharge holes provided in four stages in the depth direction according to the injection step.
The air generator is connected so as to be able to pump gas to each air packer member through an air pipe communicating with five air packer members that block the space between the upper and lower parts of the injection step.
It has an inner tube in which four injection pipes are arranged and bundled around one air pipe.
The multi-stage simultaneous injection device, wherein the inner pipe is inserted into the outer pipe and is configured to be able to move up and down with respect to the outer pipe. The multi-stage simultaneous injection device according to claim 1, wherein the grout injected by the injection pump is a one-component grout having a gelation time of 30 minutes or more. A multi-stage simultaneous injection method for simultaneously infiltrating grout into the sandy soil particle gaps in a plurality of stages in the depth direction to stop water and strengthen the ground by using the multi-stage simultaneous injection device according to claim 1 or 2.
Gas is sent from the air generator to the air packer member through the air pipe, each of the five air packer members is inflated, and an air packer expansion step of closing between the upper and lower parts of the injection step is performed.
Then, using the injection pump, grout injection is simultaneously injected into four stages at a low discharge rate of 1 to 8 L per minute from the discharge holes of the injection pipes installed in four stages in the depth direction according to the injection step. As well as performing the process
A multi-stage simultaneous injection method characterized in that the inner pipe is pulled up to the upper injection step, the air packer expansion step and the grout injection step are repeated, and the grout is injected every four injection steps.

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