JPH08120662A - Injection method for plastic grout - Google Patents

Abstract

PURPOSE: To improve development of early strength by a method wherein plastic grout made of a suspension, mainly composed of a hardening developing material, and water glass is injected at a specified running speed and a pressure through an injection pipe having a section in a specified size. CONSTITUTION: Liquid A, made of a suspension mainly composed of a hardening developing material such as cement, and liquid B, made of water glass, are supplied under pressure respectively from a tank 5 for the liquid A and a tank 7 for the liquid B with flow-rate controlling pumps 6 and 8. The liquid A and the liquid B are joined together and mixed by a line mixer 9, and the mixed liquid is gelled at a point near the port of an injection pipe 2. Then, plastic gel is discharged from an injection port through the injection pipe 2, that is in a section approximately uniform all over the length from a point where the liquid A and the liquid B join together to the injection port, at the speed of 5m/sec. or below and the injection pressure of 9kgf/cm<2> or below, and furthermore the value obtained by multiplying the speed by the square root of the injection pressure is set at about 5 or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to large gaps and cavities such as gravel layers in soft ground (cavities in natural ground and cavities at the boundary between structures and natural ground, eg backfilling of shield tunnels).
The present invention relates to a method for injecting and filling a two-component water glass-based plastic grout.

[0002]

2. Description of the Related Art Generally, a two-liquid water glass grout is
Both have the characteristics of gelation-curing process as shown in the graph of FIG.

Of these, LW, which is a typical warm-up type grout, has a gel time of about 1 minute when liquid A (suspension) and liquid B (water glass) are mixed, as shown in FIG. Fluidized and solidified (they are gelled but the grout itself does not have the strength to stand on its own and has the physical physical property of fluidity) and the plasticized solidified region (the grout itself has no fluidity, , Has the property of forming a firm gel (hereinafter referred to as a consolidated grout) through a consolidation region (which does not flow with a slight increase in pressure) through a slight pressure).

However, there is a property that the strength development after consolidation is very small.

As described above, in the injection of the solidified grout, since the fluidized and plastic solidified regions are very short immediately after gelation, the solidification (gelation) of the grout is caused between the soil particles in the ground or in the cavity. Will be done in.

[0006] Therefore, the solidified grout is not kneaded (disturbed) by the pressure and flow velocity of the grout itself, so that it is injected without being disturbed by the kneading. be able to.

[0007] However, since the solidified grout has a long gel time, it has a drawback that it is diluted with water before gelling and causes material separation, which makes it impossible to obtain a uniform solidifying strength. Since there is no expression (after 1 to 3 hours), it is not possible to quickly expect a consolidation strength equal to or higher than that of the natural ground.

[0008] For this reason, in the ground injection, multi-layered ground (gravel, sand,
When targeting silt, clay, etc.), suspension type grout (high homogel strength) such as LW has poor permeability, so it is injected into rough soil (gravel, etc.) or layer boundary and ground After making the whole uniform, a method of injecting a solution type grout with good permeability into fine soil is used.

In this case, if the strength of the suspension type grout to be injected first is not higher than a certain level (usually a solidification strength corresponding to the injection pressure is required), the solution type grout to be injected later is a suspension type grout. It will be pressed into the grout and an effective compound injection will not be obtained.

For this reason, the suspension type grout must have a solution type grout to be performed until it reaches a certain strength or more, and as a result, workability and workability are deteriorated.

Also in the backfill injection, LW (consolidation type) has a long gel time, so that it is diluted with water before gelling, and the materials are separated, so that a uniform consolidation strength cannot be obtained.

Further, since the early strength is poorly expressed, the strength equivalent to the natural ground cannot be obtained promptly, and there is a drawback that the ground change (subsidence) occurs without being able to withstand the pressure of the surrounding natural ground. Rarely used.

A plastic grout has been developed to solve the problems of the solidified grout.

This plastic grout is the above-mentioned consolidated LW.
Unlike that, the caking strength is very weak immediately after gelation, but a remarkable strength development is observed early, and a caking strength of about 1 Kgf / cm2 or more is obtained after 3 hours.

Further, the plastic grout has a short gel time (about 20 seconds or less), is not diluted with ground water, and has a uniform solidifying strength. Further, the plastic grout has a plastic region (5 to 30) immediately after gelation. (Less than a minute) and has excellent filling properties, and is effective for the above-mentioned ground injection and backfill (cavity) injection.

However, since the plastic grout is injected in a very weak gel state called a plastic gel at the time of injection,
Depending on the injection method, that is, the injection conditions, the plastic gel is kneaded (disturbed) to destroy the gel, which has a fatal defect of inhibiting the development of early strength peculiar to water glass-based grout.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problem of inhibiting the early development of strength due to the kneading of the plastic gel at the time of injection, a curing agent is used as a main component as a liquid A. A method in which a suspension and water glass as solution B are pressure-fed by separate injection pipes, mixed and mixed in front of the injection port to generate a plastic gel before reaching the injection port, and the method is described below. [A], [B], [C], [D]
It is an injection method of plastic grout characterized by satisfying the condition of.

[A] The flow rate of the plastic grout discharged from the inlet is not more than about 5 m / sec.

[B] The injection pressure of the plastic grout discharged from the injection port is about 9 Kgf / cm 2 or less.

[C] The value obtained by multiplying the flow velocity of [A] by the square root of the pressure of [B] is about 5 or less.

[D] The cross section of the injection pipe from the junction of liquids A and B before the injection to the injection port has almost the same size.

The invention of the above configuration is proposed.

Further, according to the present invention, a suspension containing a curing agent as a main component as a liquid A and a water glass as a liquid B are pressure-fed by separate injection pipes, respectively, and are mixed and mixed in front of the injection port to be plasticized. A method for forming and injecting the gel-like gel at the same time as or immediately after the release at the injection port, which comprises
A method for injecting a plastic grout characterized by satisfying the conditions [B] and [C].

[A] The flow rate of the plastic grout discharged from the inlet is not more than about 5 m / sec.

[B] The injection pressure of the plastic grout discharged from the injection port is about 5 kgf / cm 2 or less.

[C] The value obtained by multiplying the flow velocity of [A] by the square root of the pressure of [B] is about 5 or less.

The invention having the above-mentioned configuration is proposed.

In the case of ground injection, the term "released injection port" as used in the present invention means the time at which the tip of an injection pipe (generally a double pipe is used because the gel time is short) is press-fitted into the ground, which is backfill injection. Then, it means the time when you leave the grout hall and enter the rocky ground.

The flow rate of the present invention refers to the flow rate of plastic grout at the inlet (also referred to as the injection speed), and the pressure refers to the pressure of the plastic grout at the inlet, which is a normal injection pump. It is not a pressure gauge attached to.

The hardening developing agent for the liquid A used in the method of the present invention is a material containing cement, slag and cement, slag and lime or cement slag, sand and the like as a main component and hardening by adding water.

Further, the suspension of the liquid A is a hardening manifesting material alone or to which an adhesive agent such as clay mineral or fine particle aggregate is added, and further, if necessary, a dispersant, a retarder, etc. are added. Agents can be added.

The water glass used in the liquid B of the present invention is not particularly limited, but preferably has a molar ratio of about 3 or more.

[0033]

According to the present invention, as a result of various experiments conducted to solve the problem of inhibiting the early development of strength due to the kneading of the plastic gel during the injection, the cause of the kneading of the plastic gel is the first. Is the flow rate of the plastic gel itself, and second is the pressure at that time. The third cause is that the shape of the injection pipe, that is, the plastic gel is formed in the injection pipe up to the injection port. In the case of injection, it was found that if the cross section of the injection tube is uneven, the plastic gel causes a kneading phenomenon regardless of the flow rate and pressure, and the development of early strength is inhibited.

When the flow rate of the plastic gel grout of the first cause exceeds about 5 m per second, and the pressure of the grout itself of the second cause exceeds about 9 Kgf / cm 2, the kneading phenomenon is large and the early strength is high. Expression is extremely reduced.

Experiments have also revealed that there is a certain range between the flow velocity and the pressure even if the flow velocity and the pressure are under the above conditions. That is,

1) The flow rate (injection rate) of the plastic grout discharged from the injection port is about 5 m or less per second.

2) The injection pressure of the plastic grout discharged from the injection port is about 9 Kgf / cm 2 or less.

3) Further, even if the flow velocity and the pressure are under the above conditions, there is a certain relationship between them, but from the experimental results, the flow velocity (m / sec) multiplied by the parallel root of the pressure is used as the standard. Was found to be in the range of about 5 or less.

The plastic grout referred to in the present invention is
A grout having a plasticity retention time (detailed in Experiment-1) of about 5 minutes or more.

[0040]

EXAMPLES The present invention will be described in detail below with reference to examples.

The water glass used in the experiment has a specific gravity of 1.32, Na 2 O,
An aqueous solution of 8.6%, SiO2 26.5%, ordinary Portland cement (hereinafter referred to as cement) was used as a hardening agent, and bentonite (250 mesh) was used as a thickener.

"Experiment-1 (Comparative Example)" ... Immediately before gelation in order to see the gel time and early strength development (old) of the compound of Table 1 of suspension type injection material LW as a conventional consolidation (type) grout. The result of Experiment No. 1 in Table 2 was obtained by filling a mold having a diameter of 5 cm and a height of 10 cm, and curing the composition in a stationary state.

[0043]

[Table 1]

[0044]

[Table 2]

In order to measure the plasticity retention time,
According to the test using a static penetration resistance measuring machine (asphalt penetration test JIS K 2530-1961), the static penetration resistance value was measured using a 36 mm long penetration cone with a total weight of 230 g and a tip angle of 15 degrees. It was measured.

In this test, the penetration value after gelation is 15
It took about 30 seconds to reach mm (this penetration value
15 mm corresponds to a uniaxial compressive strength of about 0.1 Kgf / cm2 and was the upper limit of the plastic consolidation strength).

From the above two experiments, solidified grout LW
The gel time was about 50 seconds, but it can be seen that the plastic consolidation area is very short from immediately after gelation to the consolidation area, and the initial strength (old level) is not so much expressed.

[Experiment-2 (Example)] In order to see the gel time and early strength development of the plastic grout of the present invention, the plastic grout was packed in a mold having a diameter of 5 cm and a height of 10 cm immediately before gelation and left standing. The results of Experiment No. 2 in Table 4 were obtained when the measurement was carried out by training in.

[0049]

[Table 4]

On the other hand, immediately after gelling the formulations shown in Table 3 in a plastic bag, knead well by hand to completely break the gel (by kneading, the plastic consolidated gel is fluidized and consolidated. 5cm diameter and 10cm height
After filling in the mold of No. 3 and curing in a state of standing, the results of Experiment No. 3 in Table 4 were obtained.

[0051]

[Table 3]

Further, when the plasticity (consolidation) grout was gelled and was allowed to stand still, the plasticity retention time was carried out according to the method of the consolidation grout of the above Experiment-1, and the penetration value after gelation was 15 mm. It took about 30 minutes to reach.

From the above experiments, the plastic grout of the present invention has a very short gel time, but the plasticity retention time is very long, about 30 minutes, and the early development of strength is extremely high when the plastic grout is left standing after gelation. It turns out to be remarkable.

On the other hand, in Experiment No. 3 in which the mixture was kneaded with the plastic grout immediately after gelling, the caking strength was about 1/5 in 3 hours as compared with Experiment No. 2 and 1 in 1 day. It turns out to be extremely low at / 12.

A graph of the results of Experiment No. 1 of Experiment 1 and Experiment No. 2 of Experiment 2 is shown in FIG.
The characteristics of the curing process are shown.

“Experimental apparatus (a)”: flow rate and injection pressure of grout in the plastic consolidation region (including fluid consolidation region) immediately after gelation of grout (plastic consolidation type and consolidation type) In order to see the effect of, the experiment was performed using the experimental apparatus shown in FIG.

Grout kneading device 1 shown in FIG.
Is an iron box-shaped body having a width almost the same as that of the injection pipes 2 connected to the front and back thereof, and a plurality of partition plates 3 are alternately installed inside the top and bottom so that a gap is formed at the tip thereof, thereby forming a meandering shape. The flow path is formed so that the pebbles 4 are packed therein, and the total cross-sectional area of the gap between the pebbles 4 in the cross-section of this flow path is made substantially the same as the cross-sectional area of the injection pipe 2.

The liquid A is pumped from the liquid A tank 5 to the injection pipe 2 by the flow rate control pump 6, and the liquid A is pumped from the liquid B tank 7 to the flow control pump 8 so that A and B
Both liquids are combined and mixed by the line mixer 9, and the flow velocity and pressure of the mixed liquid are adjusted to predetermined flow velocity and pressure by the flow rate adjusting valve 12 while being measured by the flow meter 10 and the pressure gauge 11.
The pressure is fed to the kneading device 1.

After mixing the liquids A + B, the kneading device 1
The gel is formed in the vicinity of the mouth of the injection pipe 2 before entering, and the grout (A of the plastic consolidation region (including the fluid consolidation region))
+ B liquid) is kneaded while passing through the gap of the pebbles 4 in the flow path of the kneading device 1, and the grout of the plastically consolidating region discharged from the outlet at the tip is a vinyl chloride half-divided cylinder with a diameter of 5 cm. The sample was collected as a sample by filling the sample collecting mold 13, which is a container.

A pressure gauge 11 'and a flow rate adjusting valve 12' are also installed in the injection pipe 2 on the outlet side of the kneading device 1.

The uniaxial compressive strength of the collected sample was measured 3 hours after gelation.

"Experimental apparatus (b)": In order to see the phenomenon in which the plastically-consolidated grout twists when passing through an uneven injection tube, the experimental apparatus shown in FIG. 2 was used.

Grout kneading device 14 shown in FIG.
Is a structure in which 2-inch short pipes 14a and 1-inch short pipes 14b having different cross-sectional areas are alternately connected, and the liquid A and the liquid B are confluently mixed and gelated in the same manner as in the experimental apparatus a, and the plasticity A turbulent flow was generated while the grout (solution A + B) was alternately passed through the short tubes 14a and 14b, and the mixture was kneaded, and was allowed to enter a sampling mold 13 similar to that used in the experimental apparatus a, which was attached to the discharge port. Is configured to create.

The injection pipe 2 in front of the kneading device 1
A flow meter (velocity meter) 10 and a pressure gauge 11 are attached to the same as in the experimental device a.

[Experiment-3 (Comparative Example)] As a preliminary test before using the grout using the experimental apparatus a, in order to make the flow velocity and the pressure in the grout kneading apparatus 1 constant, a flow was performed using water. The flowmeter and pressure gauge at the inlet and outlet were activated and adjusted.

Then, using the experimental apparatus a, the flow rate on the injection side of the solidified grout (compound of Table 1) was changed to 0.6 per second.
When pressure was fed at 8 m at a pressure of 1.0 Kgf / cm 2, a grout sample in a plastically consolidated region was obtained from the sampling container 13 through the outlet.

After the injection, when the kneading device was opened, a small flow passage (estimated from the layer cross section where the cement particles settled was estimated to be 10 m / m or less) was confirmed as if the grout had passed to the end, and solidification around it was confirmed. The strength was almost uniform.

The uniaxial compressive strength of the collected consolidated grout after 3 hours was 0.64 kgf / cm 2.

Further, as in the above, the injection pressure is 10 kgf / cm2,
The uniaxial compressive strength of the test piece obtained after adjusting the flow rate to 7.5 m per second after 3 hours was 0.60 kgf / cm 2.

On the other hand, solidified grout was added to the uneven injection pipe of FIG. 2 at a flow rate (flow rate of a 2-inch pipe of 60 liters / minute) per second.
3 of the specimens obtained by pressure feeding at 0.51 m and pressure of 8.0 Kgf / cm2
The uniaxial compressive strength after time was 0.63 Kgf / cm2.

As described above, the solidified grout was compared with the uniaxial compressive strength in the stationary state (Table 2), and after 3 hours after the kneading phenomenon was caused using the experimental apparatus a and the experimental apparatus b. It was found that there was not much difference from the uniaxial compressive strength and that it was hardly affected.

[Experiment-4 (Example)] Using the experimental apparatus a, as in Experiment-3, the initial strength due to the kneading phenomenon under the influence of the flow velocity and pressure of the plasticized grout having the composition shown in Table 3 was used. An experiment for confirming the presence or absence of expression was conducted and the results shown in Table 5 were obtained.

This experiment was carried out by a method in which the liquid A and the liquid B were mixed and mixed and passed through the injection tube 2 shown in FIG. 1 and simultaneously a plastic gel was produced.

[0074]

[Table 5]

It is clear from Table 4 that the expression of early strength of the plastic grout (after 3 hours) is greatly influenced by the kneading of the grout. The degree of this kneading is shown in Table 5 and the flow rate of the grout and the It can be seen that it is greatly affected by pressure.

That is, early strength of grout (after 3 hours)
In Table 4, the uniaxial compressive strength when allowed to stand after gelation in Table 4 is 1.60 kgf / cm2, while the reduction to about 1.0 Kgf / cm2, which is about 40% reduction, is within the scope of the present invention.

Accordingly, when the plastic grout gel of the present invention is produced at the same time as or immediately after the release at the injection port,

[A] The flow rate of the plastic grout discharged from the inlet is not more than about 5 m / sec.

[B] The injection pressure of the plastic grout discharged from the injection port is about 9 kgf / cm 2 or less.

[C] Further, it should be about 5 or less of the value obtained by multiplying the flow velocity of [A] by the square root of the pressure of [B].

It is necessary to satisfy the above three conditions, and in Table 5, a range surrounded by the thick lines is shown as a range satisfying these conditions.

[Experiment-5 (Example)] .. The plastic grout gel was flown to the kneading device 14 having a concavo-convex tubular shape with different tube diameters shown in FIG. 2 (flow rate of 2 inches, 30 liters / minute).
The uniaxial compressive strength of the obtained test piece after 3 hours was 0.61 kgf / cm2 after pressure-feeding at 0.25 m / sec and a pressure of 1 kgf / cm2.

Similarly, the uniaxial compressive strength after 3 hours of the test piece obtained by pressure-feeding at 0.51 m / sec (flow rate of 2-inch tube: 60 liter / min) at 7 kgf / cm2 was 0.54 kgf / cm2. .

As described above, when the plastic grout gel of the present invention is formed and then pressure-fed to short pipes having different cross-sectional areas of 2 inches and 1 inch, the early strength of the gel is that of the gel when left standing. Uniaxial compressive strength of 1.60kgf / cm2 compared with 0.61kgf /
It was found that cm2 and 0.54 kgf / cm2 could not reach 1.0 kgf / cm2, which is the range of the present invention.

From this, it is understood that the condition of the plastic gel is that the cross-sections of the injection tube have almost the same size.

[0086]

INDUSTRIAL APPLICABILITY As described above, by injecting by the method according to the present invention, even if the plasticity-holding time of the plasticity grout is extremely long, the insufflation strength is the same as the early strength development when the plastic grout is left standing after gelation. The expression of can be significantly increased.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of an experimental apparatus a used in the present invention.

FIG. 2 is a vertical cross-sectional side view of the experimental apparatus B used in the present invention.

FIG. 3 is a diagram showing the characteristics of the gelling-curing process of grout.

[Explanation of symbols]

 1 Kneading device 2 Injection pipe 3 Partition plate 4 Pebble 5 A liquid tank 6 Flow control pump 7 B liquid tank 8 Flow control pump 9 Line mixer 10 Flow meter 11 Pressure gauge 11 'Pressure gauge 12 Flow rate adjustment valve 12' Flow rate adjustment valve 13 Sampling mold 14 Kneading device 14a 2 inch short tube 14b 1 inch short tube

Claims (2)

[Claims] 1. In a method for injecting plastic grout into a large gap or a cavity of soft ground, a suspension containing a hardening agent as a main component as a liquid A and a water glass as a liquid B are respectively provided as separate injection pipes. It is a construction method in which the mixture is mixed under pressure in front of the injection port to form a plastic gel before reaching the injection port and injected. An injection method of plastic grout characterized by satisfying the conditions. [A] The flow rate of the plastic grout discharged from the inlet is about 5 m / sec or less. [B] The injection pressure of the plastic grout discharged from the injection port is about 9 Kgf / ^cm 2 or less. [C] The value obtained by multiplying the flow velocity of [A] by the square root of the pressure of [B] is about 5 or less. [D] The cross section of the injection pipe from the confluence point of the A liquid and the B liquid before the injection to the injection port has almost the same size. 2. In a method of injecting plastic grout into large gaps or cavities of soft ground, a suspension containing a hardening agent as a main component as a liquid A and water glass as a liquid B are respectively provided as separate injection pipes. Is a method for forming and injecting a plastic gel at the same time as or immediately after the release when the mixture is mixed and mixed in front of the injection port and discharged at the injection port.
A method for injecting a plastic grout characterized by satisfying the conditions [B] and [C]. [A] The flow rate of the plastic grout discharged from the inlet is about 5 m / sec or less. [B] The injection pressure of the plastic grout discharged from the injection port is about 5 Kgf / ^cm 2 or less. [C] The value obtained by multiplying the flow velocity of [A] by the square root of the pressure of [B] is about 5 or less.