JP5759201B2 - Cement injection material injection method - Google Patents

Description

  The present invention relates to a method for injecting cement-based injection material.

  In constructions such as strengthening the foundation ground, seismic reinforcement, preventing liquefaction, and reinforcing dams and tunnels, cement-based injections are injected into the ground to strengthen the ground. When strengthening the ground by injecting cement-based injecting material, it is required to efficiently reinforce a wide area in the ground, and for that purpose, the condition that cement particles easily penetrate into the gaps between the particles constituting the ground. It is advantageous to perform grouting.

  In order to perform grouting under conditions that allow cement particles to easily permeate, conventionally, the injection of cement milk is sequentially switched from poor to rich. If the cement milk containing a rich mixture is continuously injected, the ground is easily clogged with cement particles from the initial injection stage. If the ground is clogged with cement particles at the initial stage of injection, the injection pressure rises, making it impossible to inject cement milk at an early stage, thus preventing the penetration of cement particles. Therefore, as a conventional injection method, cement cement with poor blending is injected at the initial stage of injection, and then the cement milk is clogged with cement particles at the initial stage of injection by sequentially switching the blending of cement milk from poor blending to rich blending. There is an injection method that prevents cement and facilitates penetration of cement particles.

  Alternatively, the cement particles used in the cement milk can be easily penetrated between the ground particles by using a cement having a small particle diameter. Conventionally, an ultrafine particle cement having a maximum particle size of 18 μm and a size of 2.2 μm or less has been disclosed as an ultrafine particle cement-based injectant that is a cement-based injectant having a small particle system (see, for example, Patent Document 1). Moreover, the ultra-ultrafine particle cement whose particle amount of a particle size of 1-5 micrometers is 60-80% volume% is also disclosed (for example, refer patent document 2).

Japanese Patent No. 3423913 JP 2007-238428 A

  However, in the conventional injection method that switches the blending of cement milk from poor to rich, the concentration of cement entering the ground decreases as the distance from the injection port increases, and the strength in the ground tends to be uneven. There was a problem. In order to ensure a certain level of strength in the ground, it is conceivable to arrange the injection points at a high density or adjust the cement injection amount. However, these methods have a problem in that work man-hours and wasteful use of cement occur.

  On the other hand, when the ultra fine particle cement or the ultra ultra fine particle cement is used, it is possible to improve the work man-hour. However, these problems have not been greatly improved, and the amount of cement used may tend to increase. In particular, the ultra-fine particle cement is highly demanded for the suppression of the amount of use thereof because it takes time and effort during production.

  Accordingly, an object of the present invention is to provide a method for injecting cement-based injecting material that can inject cement particles in a wide range and can suppress the amount of ultra-fine particle cement used.

The injection method of the cement-based injection material according to the present invention that has solved the above problems is a method of injecting a cement-based injection material that injects a cement-based injection material into the reinforcement target ground and reinforces the reinforcement target ground, An injection port insertion step of inserting an injection port at a predetermined location in the ground to be reinforced, and an ultra-fine particle cement system having an average particle size larger than that of the ultra-fine particle cement-based injection material and having an average particle size of 1 to 3 μm from the injection port It includes a preceding injection step of injecting an injection material in advance and a subsequent injection step of injecting an ultrafine cementitious material having an average particle diameter of 3 to 5 μm from the injection port.

  In the cement-based injection material injection method according to the present invention, an ultra-fine particle cement-type injection material having an average particle diameter of 1 to 3 μm is injected in advance. For this reason, since the ultra-fine particle cement-based injecting material having a small average particle size penetrates into a region far from the injection port, the cement particles can be injected while exhibiting high permeability in a wide range. When the prior injection of the ultra-fine particle cement-based injection material is completed, the ultra-fine particle cement having an average particle size of 3 to 5 μm is subsequently injected. By injecting the ultrafine cement injection material after the injection of the ultra ultra fine cement injection material, the ultra ultra fine cement injection material is pushed out to the far region of the injection port by the ultra fine particle cement injection material. For this reason, the filling property of the cement particles in the far region of the injection port can be enhanced. In addition, since the ultra-fine particle cement-based injection material having a small particle size permeates in the region far from the injection port, the possibility of clogging can be reduced.

  On the other hand, in the region near the injection port, the penetration range of cement particles is narrow, so even when using an ultrafine cement injection material without using an ultra ultra fine cement injection material, the possibility of clogging is low, High filling ability can be exhibited. Therefore, the cement particles can be injected in a wide range, and the amount of the ultra-fine particle cement used can be suppressed.

  Here, it can be set as the aspect by which the water cement ratio W / C of the ultra-ultrafine particle cement type injection material is 400 to 1600%.

  Thus, when the water cement ratio W / C of the ultra-fine particle cement-based injecting material is set to 400 to 1600%, it is possible to more suitably inject cement particles in a region far from the injection port.

  Moreover, it can be set as the aspect which further includes the intermediate | middle injection | pouring process which inject | pours the injection material of a poorer compound than an ultra-ultrafine particle between a preceding injection | pouring process and a subsequent injection | pouring process.

  In this way, by injecting the poorly blended ultra-fine particle cement-based injection material that is poorer than the ultra-fine particle cement-based injection material between the preceding injection process and the subsequent injection process, in a region far from the injection port The permeability of the cement-based injection material can be further increased. As a result, cement particles can be injected at a higher concentration in a wide range.

  Further, when the cement-based injection material is injected in the process between the preceding injection process and the subsequent injection process, the cement-based injection material can be injected by dynamic injection or ultrasonic vibration imparting injection.

  Thus, in injecting the cement-based injection material, by filling the cement-based injection material by dynamic injection or ultrasonic vibration imparting injection, it is possible to further improve the filling properties of cement particles in a region far from the injection port. .

Further, the ultra-fine particle cement contains 2 to 25% by mass of cement clinker having a content of 3CaO · Al ₂ O ₃ of 5% by mass or less, 74 to 97% by mass of blast furnace slag, and 1 to 5% by mass of gypsum, It can be set as the aspect formed by mixing the ultra-fine particle cement with the particle size of 1-5 micrometers in a body being 60-80 volume%.

  Thus, the ultra-fine particle cement-based injection material can be suitably manufactured by using the above-described blending and components.

  According to the method for injecting cement-based injection material according to the present invention, cement particles can be injected in a wide range, and the amount of ultra-fine particle cement used can be suppressed.

It is a figure which shows typically the ground in which the cement type injection material was inject | poured. It is process drawing explaining the process of inject | pouring a cement type injection material. FIG. 3 is a process diagram illustrating a process following FIG. 2. It is a block diagram of the test apparatus used for the one-dimensional injection test. It is a table | surface which shows the grout used for the test, and a test result. It is a graph which shows the uniaxial compressive strength distribution in a test body. (A) is a diagram schematically showing the ground into which only an ultrafine cement injection material is injected, and (b) is an injection of an ultra fine cement injection material after an ultra ultra fine cement injection material is injected. It is a figure which shows the done ground typically.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each embodiment, portions having the same function are denoted by the same reference numerals, and redundant description may be omitted.

  The cement-based injection material injection method according to this embodiment is performed at the time of so-called secondary injection in an injection method such as a double pipe strainer method or a double packer method. In general, in the double tube strainer method, primary injection that is instantaneously coupled and secondary injection that is loosely coupled are performed. In the double packer construction method, there are primary injection by injection of cement bentonite material (CB material) and secondary injection by slow setting. This embodiment is performed at the time of secondary injection in these construction methods, so that it is possible to inject cement particles in a wide range more effectively and to suppress the amount of ultra-fine particle cement used. Can do.

  In the cement-based injecting method according to the present embodiment, the ultra-fine cement and the ultra-fine cement are mixed and stirred in water to form a slurry-like cement-based injecting material to be reinforced. inject. The ultra-fine cement cement-based injection material used here is composed of, for example, ultra-fine cement containing Portland cement or Portland cement clinker, blast furnace slag, and gypsum as essential components. The ultrafine particle cement-based injection material has a maximum particle size of about 10 to 16 μm and an average particle size of 4.0 μm. As the ultrafine cementitious injection material, one having an average particle diameter of 3 to 5 μm is used.

In addition, the ultra-fine particle cement-based injecting material has a content of 3CaO · Al ₂ O ₃ · of 5% by mass or less, 2 to 25% by mass of cement clinker, 74 to 97% by mass of blast furnace slag, and 1 to 5% by mass of gypsum. And an ultra-fine particle cement having a particle size of 1 to 5 μm in the powder of 60 to 80% by volume and a polycarboxylic acid dispersant are mixed as essential components. The ultra-fine particle cement-based injection material has an average particle size of 1.5 μm. As the ultra-fine particle cement-based injection material, one having an average particle diameter of 1 to 3 μm is used.

  As a preferable form of the ultra-fine particle injection material composition, the polycarboxylic acid dispersant is a repeating unit derived from an unsaturated polyalkylene glycol monomer and a repeating unit derived from an unsaturated carboxylic acid monomer. It is the form containing the polycarboxylic acid-type copolymer which has this. Furthermore, it is preferable that the method for producing the ultra-fine particle cement-based injection material has a high-speed stirring step of mixing and stirring at a peripheral speed of 314 m / min or more.

  Furthermore, it is preferable that the ultra-fine particle cement-based injection material sets the water cement ratio W / C to 400 to 1600%. This is because if the water cement ratio W / C is less than 400%, the amount of cement is large, so that clogging occurs and it is difficult to continue the injection. Further, when the water cement ratio W / C exceeds 1600%, the amount of cement is small, and it becomes difficult to secure a predetermined strength and penetration length.

  Next, the flow of the cement-based injection material in the ground when the cement-based injection material is injected into the ground by the cement-based injection material injection method according to the present embodiment will be described. When the cement-based injection material is injected into the ground, it is required that the cement in the cement-based injection material penetrates the ground in a wide range and uniformly. In the cement-based injection material injection method according to the present embodiment, as shown in FIG. 1, an ultrafine-particle cement-based injection material injection region SO in which an ultrafine-particle cement-based injection material has penetrated mainly in the vicinity of the injection port P. In the region far from the injection port P, an ultra-fine particle cement-based injection material injection region SV into which the ultra-fine particle cement-based injection material is mainly penetrated is formed.

  Since the ultrafine particle cement-based injection material has an average particle size larger than that of the ultra-ultrafine particle cement-based injection material, the permeability to the ground is inferior to that of the ultra-ultrafine particle cement-based injection material, and the improvement range becomes narrow. However, since the amount of cement is concentrated by the dewatering filtration phenomenon, the volume of cement occupying the space in the ground within the improved range increases. On the other hand, the ultra-fine cement cement-based injection material has a smaller average particle size than the ultra-fine particle cement injection material, so that it has excellent permeability to the ground and a wide range of improvement. However, since there is little concentration of cement, in order to fill the gap in the ground and obtain sufficient improvement strength, a very large amount of ultra-fine cement injection material is required. Furthermore, the ultrafine particle cement-based injection material is more likely to be clogged when injected into the ground than the ultrafine particle cement-based injection material.

  Based on these characteristics, in the present embodiment, the ultra-fine cement cement-based injecting material is injected in advance from the injection port, and then the ultra-fine particle cement-based injecting material is subsequently injected. The ultra-fine particle cement-based injection material injected into the ground penetrates around the injection port P in the ground G. Since the average particle size of the ultra-fine particle cement-based injection material is as small as 1.5 μm, the ultra-fine particle cement-based injection material is less likely to be clogged in the region near the injection port P. For this reason, it penetrates widely without causing clogging from the vicinity region of the injection port P to the far region.

  After the injection of the ultra-fine cement cement-based injection material, the subsequent injection of the ultra-fine cement cement-based injection material is performed. Already injected ultra-fine particle cement-based injection material permeates around the injection port P in the ground G. However, since the ultrafine particle cement-based injection material has an extremely small average particle size, clogging in the ground G is prevented even when the ultrafine particle cement-based injection material is injected.

  On the other hand, the average particle size of the ultrafine cementitious injection material is larger than that of the ultrafine particle cement injection material. When the ultrafine cement injection material is injected after the injection of the ultra fine cement injection material, it is pushed out by the ultra fine cement injection material, or the ultra fine cement injection material is injected into the injection port P together with the ultra fine cement injection material. It penetrates far away. In the vicinity of the injection port P, an ultra-fine cement injection material injection region SO into which the ultra-fine particle cement injection material has mainly penetrated is formed. The ultra-fine particle cement-based injection material injection region SV into which the material has mainly penetrated is formed.

  Therefore, for example, when injection is performed by arranging only a plurality of injection pipes or moving the injection pipe, and only injection is performed using an ultrafine cement cement-based injection material, as shown in FIG. The improvement is made in a state where the ultrafine cement injection material injection region SO into which the system injection material is injected is adjacent. On the other hand, when the injection of injecting the ultrafine cement cement injection material is performed after the injection of the ultra ultra fine cement cement injection material, the ultra ultra fine cement injection material SV is injected as shown in FIG. Improvement is made in the state in which the ultra-fine particle cement-based injecting material regions adjacent to each other are adjacent. Here, the ultra-ultra fine cementitious injection material region SO is formed inside the ultra-fine particle cement-based injection material region.

  In this way, clogging in the region near the injection port P can be prevented by injecting the ultrafine particle cement-based injection material in advance and subsequently injecting the ultrafine particle cement-based injection material in succession. Furthermore, since the cement-based injection material can be injected and penetrated in a wide range up to the far region of the injection port P, the strength of the reinforced ground G can be improved and the strength distribution is smooth. Thus, the strength of the ground G can be made uniform. In addition, an ultrafine cementitious injection material having a relatively large average particle size is injected in the vicinity of the injection port P. For this reason, the usage-amount of a cement type injection material, especially an ultra-fine particle cement type injection material can be suppressed.

  Next, the procedure for actually injecting cement-based injection material into the ground will be described. FIG. 2 is a process diagram showing a process when a cement-based injection material is injected into the ground. When injecting the cement-based injection material into the ground, first, as shown in FIG. 2 (a), a boring hole is drilled at a predetermined location on the ground G, which is the ground to be reinforced, and the drilled hole is drilled. The casing 1 is inserted into the housing.

  When the casing 1 is inserted into the ground G, as shown in FIG. 2 (b), the injection hose 2 is inserted inside the casing 1, and the seal grout 3 is discharged from the injection hose 2, thereby sealing the inside of the casing 1. Inject grout 3. The seal grout 3 has fluidity and is solidified with the passage of a predetermined time.

  When the seal grout 3 has been injected, the injection hose 2 is pulled out of the casing 1 before the seal grout 3 is solidified. Thereafter, as shown in FIG. 2C, the sleeve pipe 4 is inserted inside the casing 1. The sleeve pipe 4 is inserted before the seal grout 3 is solidified.

  A pipe cap 5 that closes the lower opening of the sleeve pipe 4 is provided at the lower end of the sleeve pipe 4. For this reason, the penetration of the seal grout 3 into the sleeve pipe 4 when the sleeve pipe 4 is inserted into the casing 1 is prevented. A plurality of inlets 4A, 4B, 4C, 4D are formed on the side surface of the sleeve pipe 4 at predetermined intervals in the length direction. Cement-based injection material is injected from these injection ports. The insertion of the sleeve pipe 4 is an injection port insertion process.

  When the insertion of the sleeve pipe 4 is completed, the casing 1 is pulled out from the hole formed in the ground G before the seal grout 3 is solidified. Then, after waiting for a while, the seal grout 3 in the hole is solidified. When the seal grout 3 is solidified, a solidified seal grout 6 is generated between the sleeve pipe 4 and the ground hole G in a state where the inside of the sleeve pipe 4 is hollow.

  Thereafter, as shown in FIG. 3 (a), the double packer 7 is inserted inside the sleeve pipe 4 which is hollow, and is arranged on the side of the inlet 4A located at the top. The double packer 7 is provided with an injection pipe, and the cement-based injection material is discharged into the sleeve pipe 4 by operating the injection pipe. Here, as the cement-based injection material, the ultra-fine particle cement-based injection material is discharged in advance.

  Thereafter, by continuing to discharge the ultra-fine particle cement-based injection material, as shown in FIG. 3 (b), the ultra-fine particle cement-based injection material is discharged from the injection port 4A in the sleeve pipe 4 and cracked laterally. C is formed, and the ultra-fine cementitious injection material penetrates into the cracking C. In this way, injection of the ultra-fine particle cement-based injection material into the ground G is performed as a preceding injection step.

  When the ultra-fine particle cement-based injection material penetrates to a predetermined range in the ground G, the double packer 7 is moved to the side of the lower inlet 4B as shown in FIG. Inject ultra-fine particle cement-based injection material. Thereafter, the double packer 7 is disposed on the side of the similar injection ports 4C and 4D, and the ultra-fine particle cement-based injection material is injected into the ground G.

  In the embodiment shown in FIG. 3, injection is started by a so-called step-down construction procedure in which injection is started from the injection port 4 </ b> A arranged at the top, and the injection is gradually lowered to the injection ports 4 </ b> B to 4 </ b> D positioned below. However, the injection can also be performed by a so-called step-up construction procedure. When performing the injection in the step-down construction procedure, first, the injection is started from the injection port 4D arranged at the lowermost position, and the injection is gradually performed up to the injection ports 4C to 4A located at the upper side.

  Thus, after the injection of the ultra-fine particle cement-based injection material is completed, the cement-based injection material discharged from the double packer 7 to the sleeve pipe 4 is changed from the ultra-fine particle cement-based injection material to the ultra-fine particle cement-based injection material. An injection process is performed. Subsequent injection of the ultrafine cementitious injection material is performed by the same procedure as the preceding injection of the ultrafine particle cementitious injection material. Thus, as shown in FIG. 1, it is possible to inject the ultra-fine particle cement-based injection material mainly into the region far from the injection port, and mainly the ultra-fine particle cement-based injection material into the region near the injection port. Can be injected.

  Next, the penetration state of the cement-based injecting material when the ultra-fine particle cement-based injecting material is injected in advance and the ultra-fine particle cement-based injecting material is subsequently injected will be described. The inventors of the present invention conducted a one-dimensional injection test on the state of penetration of these cement-based injection materials. In the one-dimensional injection test, cinnabar 7 test soil was used.

  As shown in FIG. 4, in the one-dimensional injection test, the test soil is filled in a vertical acrylic cylinder 11 having an inner diameter of 5 cm and a length of 1 m, and the ends are closed with the lower lid 12 and the upper lid 13, respectively. Thus, a specimen 14 imitating the ground was constructed. The sand layer constituting the specimen 14 had a fine particle content of 6% and a relative density of 87%. A lower filter material 15 and an upper filter material 16 are provided between the lower lid 12 and the specimen 14, and between the upper lid 13 and the specimen 14, respectively.

  An injection inlet 17 is formed in the lower lid 12, and an injection outlet 18 is formed in the upper lid 13. The sample soil is filled between the lower filter material 15 and the specimen 14 and between the upper filter material 16 and the specimen 14 so that there is no gap. The length of the specimen 14 (distance between the upper end of the lower filter material 15 and the lower end of the upper filter material 16) is 97.5 cm.

  The injection inlet 17 is connected to a grout tank 21 by an injection pipe 19. The grout tank 21 is a container with a lid that can be hermetically sealed. The grout tank 21 includes a mixer 23 for agitating the grout 22. By applying a predetermined pressure from the outside, the grout 22 in the grout tank 21 is supplied from the injection inlet 17. 14 can be injected. The injection outlet 18 is connected to the outside by a discharge pipe 20, and the amount of fluid discharged from the injection outlet 18 can be measured by a graduated cylinder 24.

As the cement-type injection material used for the grout, the ultra-fine particle cement-type injection material and the ultra-fine particle cement-type injection material were used in a plurality of combinations with or without being divided into the preceding material and the following material. The cement-based injection material was blended with a water-cement ratio of W / C 600%, and was injected at a design injection amount that resulted in a volume with a gap of 100% in the sand layer. The unit cement amount was 158 kg / m ³ in any grout.

  As shown in FIG. 5, in the injection by the first grout, 100% of the ultra-fine particle cement-based injection material was injected. In the injection by the second grout, 100% of a cement-based injection material in which 50% by mass of ultra-fine cementitious cement-based injection material and 50% by mass of ultra-fine cementitious injection material were mixed in advance was injected. In the injection by the third grout, 100% of the ultrafine cement-based injection material was injected. In the fourth grout injection, 50% by volume of the ultrafine cementitious injection material was injected, and then 50% by volume of the ultrafine particle cementitious injection material was injected. In the fifth grout injection, 50% by volume of the ultra-fine cementitious injection material was injected, and then 50% by volume of the ultra-fine cementitious injection material was injected.

  In injecting the grout, water is injected into the specimen 14 from the injection inlet 17 at a constant pressure, and the water passes through the gap between the soil particles of the specimen 14 and is discharged from the discharge pipe 20 connected to the upper injection outlet 18. The soil particles were filled and the gaps between the soil particles were filled with water. Next, an experiment was conducted in which the grout 22 in the grout tank 21 was injected at a constant pressure from the injection inlet 17 so that the total grout injection amount was equal to the design injection amount. The injection amount of the grout 22 can be grasped by measuring the amount of discharged water with the measuring cylinder 24.

After injecting a grout having an injection amount equal to the design injection amount, the penetration length of the grout into the specimen (cm), the average value of uniaxial compressive strength at the age of 7 days (kN / m ² ), and its standard deviation (kN / M ² ) was determined for each of the first to fourth grouts. The result is shown in FIG.

  Furthermore, after the specimen was solidified, the specimen was cut in 10 cm increments, and the uniaxial compressive strength distribution at the age of 28 days was examined. The result is shown in FIG. In FIG. 6, specimen number 1 was assigned to the lowest specimen (injection inlet 17 side) of the cut specimen, and specimen number 2 was assigned to the specimen above it. Furthermore, specimen numbers increased in order of specimen number 3, specimen number 4... Further, the first grout is indicated as “USF”, the second grout as “USF + SF”, the third grout as “USF → SF”, and the fourth grout as “SF”.

As shown in FIGS. 5 and 6, in the first grout made of the ultra-ultrafine particle cement-based injection material, the permeation length was 100% and permeated throughout the entire specimen. In addition, the uniaxial compressive strength decreases as the specimen advances from the injection inlet 17 to the injection outlet 18, and the average is 1422 kN / m ² , the variation coefficient indicating the intensity variation is 39%, and the standard deviation is 559 kN / m ² . The variation was large.

Moreover, in the 2nd grout which mixed the ultra-fine particle cement-type injection material and the ultra-fine particle cement-type injection material, the penetration length was 80 cm, and the sample was clogged. Further, the uniaxial compressive strength had a distribution with unevenness, and the average was 2070 kN / m ² , the variation coefficient was 40%, and the standard deviation was 822 kN / m ^2, and the variation was large.

Further, in the third grout using the ultrafine cement cement-based injecting material, the permeation length was 60%, resulting in large clogging. The uniaxial compressive strength was 1169 kN / m ^{2 on} average, the coefficient of variation was 28%, and the standard deviation was 324 kN / m ² , and although the variation was somewhat small, the uniaxial compressive strength itself was very small.

Moreover, in the 4th grout which used the ultra-fine-particle cement type injection material as a preceding material, and used the ultra-ultra fine particle cement-type injection material as a succeeding material, the penetration length was 100%, and the grout penetrated the entire specimen. Further, the uniaxial compressive strength has a distribution with unevenness, and the average is 1502 kN / m ² , the coefficient of variation is 69%, and the standard deviation is 1043 kN / m ² , and the variation is large.

In the fifth grout using the ultra-fine cement cement-based injecting material as the preceding material and the ultra-fine cement cement-injecting material as the succeeding material, the infiltration length was 100%, and the grout penetrated the entire specimen. Further, the uniaxial compressive strength was smoothed from the injection inlet 17 to the injection outlet 18 of the specimen, and the variation was small with an average of 1463 kN / m ² , a variation coefficient of 14%, and a standard deviation of 241 kN / m ² .

From the above results, the fifth grout in which the ultra-fine particle cement-based injecting material was pre-injected and the ultra-fine cement-based injecting material was subsequently injected resulted in small variations in the specimen. On the other hand, in the other grouts , the standard deviation tended to be larger than that of the fifth grout . Therefore, it is possible to inject the cement-based material to the far side of the injection port and to obtain a smooth distribution by injecting the ultra-fine particle cement-based injecting material first and then injecting the ultra-fine particle cement-based injecting material. Strength of can be achieved.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above embodiment, the ultra-fine cement cement-based injecting material is injected immediately after the ultra-fine particle cement-based injecting material is immediately injected. It can also be set as the aspect which inject | pouring a poor mixing | blending ultra fine particle cement type injection material as an intermediate | middle injection | pouring process between subsequent injections of a cement type injection material. As the poor blend ultra-fine particle cement-based injection material, for example, the water cement ratio W / C is 1600 to 4000%, and the integrated W / C of the preceding injection and the intermediate injection is 1600% or less. Thus, by injecting the poorly mixed ultra-fine particle cement-based injecting material, it has a predetermined strength and permeability with a smaller amount of cement. The improvement range can be expanded.

  Moreover, when inject | pouring a cement type injection material, it can also be set as the aspect which performs injection | pouring which provided dynamic injection | pouring or ultrasonic vibration. Such dynamic injection or injection given ultrasonic vibration is particularly preferably performed when injecting an ultra-fine particle cement-based injection material. By performing dynamic injection or injection with ultrasonic vibration, the cement-based injection material can be smoothly infiltrated into the ground.

DESCRIPTION OF SYMBOLS 1 ... Casing 2 ... Injection hose 3 ... Seal grout 4 ... Sleeve pipe 4A, 4B, 4C, 4D ... Injection port 5 ... Pipe cap 6 ... Solidification seal grout 7 ... Double packer 11 ... Transparent acrylic cylinder 12 ... Lower lid 13 ... Upper cover 14 ... Specimen 15 ... Lower filter material 16 ... Upper filter material 17 ... Injection inlet 18 ... Injection outlet 19 ... Injection pipe 20 ... Discharge pipe 21 ... Grout tank 22 ... Grout 23 ... Mixer 24 ... Measuring cylinder C ... Cracking G ... Ground P ... Injection port SO ... Ultra fine particle cement injection material injection region SV ... Ultra fine particle cement injection material injection region

Claims (5)

A cement-based injection material injection method for injecting a cement-based injection material into a reinforcement target ground to reinforce the reinforcement target ground,
An inlet insertion step of inserting an inlet at a predetermined location in the ground to be reinforced, and
A pre-injection step of pre-injecting an ultra-fine particle cement-based injectant having an average particle size of 1 to 3 μm from the injection port;
A subsequent injection step of injecting and injecting an ultrafine particle cement-based injection material having an average particle size larger than that of the ultra-ultrafine particle cement-based injection material and having an average particle diameter of 3 to 5 μm from the injection port;
A method for injecting cement-based injecting material, comprising:   The cement-based injection material injection method according to claim 1, wherein the ultra-fine particle cement-based injection material has a water cement ratio W / C of 400 to 1600%.   The intermediate injection process of inject | pouring the poor mixing | blending very ultrafine cementitious injection material of a poorer compound than the said ultra-ultrafine-particle cement injection material between the said pre-injection process and the said subsequent injection | pouring process is further included. Or the injection method of the cement-type injection material of Claim 2.   The cement-based injection material is injected by dynamic injection or ultrasonic vibration imparting injection in injecting the cement-based injection material in a process between the preceding injection process and the subsequent injection process. The injection method of the cement-type injection material of any one of them. The ultra-fine particle cement-based injection material includes 2 to 25% by mass of cement clinker having a content of 3CaO · Al ₂ O ₃ of 5% by mass or less, 74 to 97% by mass of blast furnace slag, and 1 to 5% by mass of gypsum. The cement-based injection according to any one of claims 1 to 4, wherein ultra-fine cement having a particle size of 1 to 5 µm in the powder is 60 to 80% by volume is mixed. Material injection method.

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