JPH0637767B2 - Ground improvement method combining agitation blades and high-pressure injection - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ground improvement method using a stirring blade and high-pressure injection for ground improvement in civil engineering and construction work.

[Prior Art] Conventionally, as an example of a method of mixing the soil of the ground and the solidifying material with a stirring blade for solidifying the ground, stirring and solidifying, and forming an improved column, a hollow rod as shown in FIG. 7 is used. 1 stage of excavating blade 2 and 3 stages of stirring blades 3 (1 to 5 stages are appropriately used) are fixed above the tip, and discharge port 4a near the tip of rod 1 and uppermost stage stirring A construction method using a ground improvement device in which a discharge port 4b is provided in the rod 1 near the wing is used. The discharge ports 4a and 4b of the rod 1 are connected to a solidified material injection pump on the ground through the rod, and one unnecessary discharge port of the discharge ports 4a and 4b is blinded by a plug during construction. The rod 1 is rotated and fed by an unillustrated construction mechanism on the ground. In order to perform construction using the ground improvement device as shown in FIG. 7, the solidified material is not filled from the discharge ports 4a and 4b in the ground, and the rod 1 is rotated while being fed and excavated, After drilling to the depth,
A method of injecting, stirring, and mixing the solidified material into the soil of the ground by discharging the solidified material pumped from a pump on the ground while rotating the rod 1 and discharging the solidified material from the discharge opening 4b. While filling up from the ground,
Feed the rod 1 while rotating the rod 1, excavate to a predetermined depth, and after stirring and mixing, stop filling the solidified material,
The method of stirring and mixing the solidified material with the soil of the ground by pulling up the rod 1 while rotating the rod 1, while filling the solidified material in the ground from the discharge port 4a, the rod 1 is advanced while rotating the rod 1. Then, after excavating to a predetermined depth and stirring / mixing, the solidifying material is further stirred from the discharge port 4b in the ground, and the rod 1 is pulled up while rotating the rod 1 to mix / solidify the solidifying material with the soil in the ground. However, there is a construction method for constructing the improved pillar 10a.

As another example, a construction method using a ground improvement device in which a high-pressure discharge port 6 is provided at the lower end of a hollow rod 5 as shown in FIG. 8 is used while rotating the rod 5 while the high-pressure discharge port 6 is being rotated.
To 50 kg / cm ^{2 to} 300 kg / cm ^{2 at} a high pressure, the rod is advanced while high-pressure jetting 6a of the solidifying material, and the high-pressure jet stirs and mixes the soil in the ground with the solidifying material to construct the improved pillar 10a. The construction method is a construction method using a ground improvement device in which a high pressure discharge port 8a provided at the lower end of the rod 7 as shown in FIG. 9 is extended to a predetermined radius by a pipe 8, and 50 kg / cm ^{2 to} 300 kg from the high pressure discharge port 8a. The solidified material is injected at high pressure 8a at a high pressure of / cm ^{2 and} the rod 7 is advanced to stir and mix the soil and the solidified material in a donut-shaped cross-section.
There is a construction method to construct.

A liquid cement-based solidifying material, water glass, or the like is used as the solidifying material.

[Problems to be Solved by the Invention] However, a device for excavating and stirring while filling a low-pressure solidifying material from the low-pressure discharge ports 4a, 4b shown in FIG. 7 and its construction method, or a device shown in FIG. According to the construction method,
As shown in FIG. 12, when each of the improved columns 10a (columns solidified after the soil and the solidifying material are stirred and mixed and solidified) is circumscribed to each other, the unmodified portion 11 is large, and FIG. As shown in FIG. 5, the unimproved portion 11 remains even when the soil-solidified columns 10a are lapped with each other in a practical range. Therefore, in the case as shown in FIG. 10, if the unimproved portion 11 is to be eliminated, the construction pitch becomes small and not practical, and the construction cost becomes high and the efficiency is unavoidable. Therefore, unmodified part 1
1 and the water from the bottom of the improved ground is unmodified 11
It was difficult to prevent climbing through.

Further, in the construction method using the device as shown in FIG. 9, the unmodified portion 11 remains in the center, and since the solidifying material is filled with the soil in a donut shape, the mixing ratio of the solidifying material is uneven and the strength is not good. There were drawbacks such as.

Further, when the construction method by the ground improvement device as shown in FIG. 7 is applied to the inside of the underground structure such as steel sheet pile, concrete wall, etc. as shown in FIG. 11, the improved pillar 10a becomes the excavation blade 2 and the stirring blade. Since the rotating tip of 3 must be installed in a state where it does not come into contact with the steel sheet pile 12, the unmodified portion 11 remains between the steel sheet pile 12 and the row of the improved columns 10a, and the steel sheet pile 12 and the improved columns 10a are It is not possible to stop the water spouting from the unmodified portion 11 without the close contact. When the ground improvement device shown in FIG. 8 and FIG. 9 is used, the steel sheet pile 12 and the improved pillar 1
However, the improved pillar 10a has a drawback that the strength and strength of the improved pillar 10a are low because mixing and stirring of the solidifying material and the soil are not uniform due to the principle of the construction method, resulting in a high construction cost.

The present invention has been made in view of the above-mentioned circumstances, in which the central portion is made into a column having a uniform and strong strength by stirring with a stirring blade, and the outer portion is brought into contact with an underground structure by mixing and stirring by high-pressure injection. Provided is a ground improvement method using a combination of a stirring blade and high-pressure jet, which can be constructed as an improved pillar surrounded by a donut-shaped pillar having a water stopping ability.

[Means for Solving the Problems] Means for solving the above problems include the following first and second claims.

(1) A ground improvement method using a combination of agitation blades and high-pressure injection, which consists of combining the following steps.

One-stage drilling blade near the tip and at least one above it
While ejecting solidified sized pressure 1kg / cm ² ~15kg / cm ² while rotating the low-pressure discharge port provided in the vicinity of the rod lower end of the pump discharge side a rod having a stepped stirring blade downward of the ground to a predetermined depth The step of feeding the rod, while rotating the rod, without discharging the solidified material from the low pressure discharge port, the pressure on the discharge side of the pump from the high pressure discharge port near the tip of the excavation blade is 50 kg / cm ^{2 to} 300 kg / cm ² (2) A ground improvement method using a stirring blade and high-pressure injection, which comprises the step of pulling up the rod while injecting the solidifying material, and (2) combining the following steps.

One-stage drilling blade near the tip and at least one above it
Predetermined depth below the ground while ejecting solidified material have a pressure of 1kg / cm ² ~15kg / cm ² in the pump discharge side from the low pressure discharge port provided in the vicinity of the rod lower end while rotating the rod with a stage stirring blades to KyuSusumu rod until step, the while the pressure at the pump discharge side from the high pressure discharge port in the vicinity of the drilling blade tip of at least the bottom while rotating the rod to inject the solidifying material of 50kg / cm ² ~300kg / cm ² The step of pulling up the rod to a predetermined depth, further, while rotating the rod, the pressure on the discharge side of the pump from the high pressure discharge port is 50 kg / cm ^{2 to} 300 kg.
A step of injecting the solidifying material of / cm ² and advancing the rod to a predetermined depth below the ground, a step of stirring and pulling up while rotating the rod without discharging the solidifying material at all.

[Operation] The strength of the central part of the improved column is high because the soil and solidifying material are mixed uniformly and well by stirring by rotating the stirring blade. The soil and the solidified material are agitated on the outer side by a high-pressure jet obtained by high-pressure injection of the solidified material, so the mixed state is a little worse and the strength is somewhat lower than in the central part. Since there is no mechanical contact with the plate, structure, etc., it is possible to work closely without any unmodified parts, and it is also possible to build large-diameter improved columns together with the central part.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

1 (a) to (d) and 2 (a) to (h),
It is a construction drawing which shows the construction order of the ground improvement construction method with a stirring blade and a high pressure injection which are the 1st claim and the 2nd claim, respectively.

In the ground improvement device used for this construction method, as shown in FIG. 3 (a), an excavation blade 22 is fixed near the tip of a double pipe rod 21, and there are three stages (one or more stages depending on soil quality and construction). The stirring blades 23, 23, 23 (which are appropriately changed according to the conditions) are provided and fixed to the rod 21.

If the co-rotation preventing devices of the patents No. 1197295 and No. 1197296, which the applicant holds, are installed, the stirring effect of the stirring blades 23 is further improved. FIG. 3B is a front view in which a co-rotation preventing blade 28, which is an example of the co-rotation preventing apparatus, is mounted. The co-rotation preventing blade 28 has a diameter larger than that of the excavating blade 22 and the stirring blade 23 and the rod 21. Since it is rotatable, the excavation blade 22 and the agitation blade 23 rotate while the rod 21 is advanced / pulled up and excavated / stirred, but the co-rotation prevention blade 28 does not excavate the ground on the outer periphery of the excavation hole. Since it does not rotate by biting into the
The non-rotating co-rotation wing 28 where the soil that is stirred and moves does not rotate
At this time, mixing and stirring are often performed.

As shown in FIG. 3 (a), a low pressure discharge port 24 is formed near the tip of the rod 21, and the excavation blade 2
A high-pressure discharge port 25 is opened at the tip of 2. Although not shown, the high-pressure discharge port 25 may be provided between the tip and the root of the excavation blade 22 with the discharge port facing the tip direction. The low-pressure discharge port 24 and the high-pressure discharge port 25 are in communication with the gap between the outer pipe and the inner pipe of the double pipe and the inner pipe, and the upper end of the double pipe is connected to the low-pressure pump and the high-pressure pump on the ground. The double pipe is rotated and fed by an unillustrated construction machine on the ground.

The construction method of the present invention comprises the first claim and the second claim, and the construction method will be described below in order.

The construction method of the first claim is shown in FIGS. 1 (a) to 1 (d). First, in the ground while ejecting solidified material of the low pressure from the low pressure discharge port 24 while rotating the rod 21 (1 kg with a pressure at the pump discharge side / cm ² ~15kg / cm ²⁾ as in FIG. 1 (a) As shown in FIG. 1 (b), the rod is advanced to a predetermined depth below the ground to excavate and simultaneously mix and mix the solidifying material and the soil to construct the central improvement column 26a. Then, the discharge of the solidified material from the low-pressure discharge port 24 is stopped, and as shown in FIG. 1 (c), the high-pressure discharge port 25 at the tip of the excavation blade is pressurized to a high pressure (pressure at the pump discharge port side is 50 kg / cm ^{2 to} 300).
kg / cm ² ) of the solidified material is injected under high pressure 25a while pulling up while rotating the rod, and the outer improvement column 26b is constructed as shown in FIG.

FIG. 1 (e) is a sectional view taken along the line AA of FIG. 1 (d). The communication improving column 26a is 5 to 30 kg / cm ² , and the outer improving column 2 is
6b has a strength of ^{2 to} 10 kg / cm ² .

The construction method of the second claim is shown in FIGS. 2 (a) to 2 (h). The steps of FIGS. 2 (a) to 2 (d) are the same as those of FIGS. 1 (a) to 1 (d), but next, FIGS. 2 (e) and 2 (f). ), While again injecting the high-pressure solidifying material from the high-pressure discharge port near the tip of the excavation blade,
Feed while rotating the rod to the predetermined depth,
Since the high-pressure jet liquid is injected through the outer improving column 26b constructed in the step (c), the outer diameter of the outer improving column 26b is enlarged, and then shown in FIGS. 2 (g) and 2 (h). As described above, the rod 21 is pulled up without rotating the solidified material.

That is, when the high-pressure solidified material is injected again from the high-pressure discharge port near the tip of the excavation blade, even though the injection pressure is the same as that in the step (c), it penetrates the outer improvement column 26b built in the step (c). Since the high-pressure jet liquid reaches the hole-drilling wall and the hole diameter is expanded, although slightly, as compared with the step (c), the outer diameter of the outer improvement column 26b is increased accordingly.

FIG. 4 is a view in which the improved columns according to the method of the present invention are wrapped without any unmodified portions, and a diagram in which the outer modified columns 26b are wrapped is shown in which the outer modified columns 26b are wrapped, so that there are no unmodified portions. Further, FIG. 6 is a view in which the unmodified portion 11 is left and the outer modified columns 26b are gradually wrapped with each other.

FIG. 5 shows the outer side improved pillar 2 of the improved pillar 26 by the construction method of the present invention.
6b is wrapped inside the steel sheet pile 12 to eliminate the unmodified portion 11 at all and enhance the water blocking effect.

[Effects of the Invention] According to the method for combined use of the stirring blade and the high-pressure injection of the present invention described in detail above, the following effects are exhibited.

There is no part of the ground that cannot be improved between the improved columns, and it is possible to improve the ground completely by stopping water.

When applying the method of the present invention to the inside of underground structures such as steel sheet piles and concrete walls, since the outer improved columns are constructions by high-pressure injection of the solidifying material, the stirring blades and the like do not hit the structure, There is no unimproved portion between the structure and the improved column, and the improved column wraps and adheres closely to the structure, so that waterproofing is complete.

Compared to the conventional construction of improved columns with large-diameter excavation blades and agitation blades, the construction of improved columns of the present invention having the same outer diameter is due to stirring and mixing by the outer improved columns by injection of high-pressure solidifying material. Because there is, horsepower is small.

In the ground improvement method, generally, the ground improvement body (improved column) constructed by high-pressure injection is poor in quality, low in strength development, and expensive, but the method of kneading the solidified material injected at low pressure with the stirring blade is high. Quality and low price.
In this respect, according to the present invention, by mixing high pressure and low pressure, the improved columns can be formed by wrapping each other so that there is no unimproved portion while keeping the strength (quality) and the economical efficiency in harmony.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) to (d) are construction method diagrams showing the construction order of the first claim, and FIG. 1 (e) is a line AA of FIG. 1 (d). Sectional views, FIGS. 2 (a) to 2 (h) are construction drawings showing the construction order of the second claim, and FIG. 3 (a) is a front view of a stirring blade used in this construction method and a high-pressure jet combined ground improvement device. Fig. 3 (b) is a front view in which a co-rotation preventive device is attached to a ground improvement device using agitation blades and high-pressure injection used in the present invention, and Fig. 4 shows an improved pillar by the construction method of the present invention without unimproved parts. Fig. 5 is a plan view constructed by wrapping, and Fig. 5 is a plan view constructed by wrapping the outer improved columns of the improved columns by the method of the present invention inside the steel sheet pile, and Fig. 6 shows the outer improved columns with the unmodified portion left. FIG. 7 is a plan view showing a partially lapped portion, FIG. 7 is a front view showing an example of a ground improvement device using a conventional stirring blade and its construction state, and FIG. 8 is a conventional solidifying material. 9 is a front view showing an example of the ground improvement apparatus by high-pressure injection and its construction state, FIG. 9 is a front view showing another example of the conventional soil improvement apparatus by high-pressure injection of solidifying material, and its execution state, FIG. 10 is Fig. 11 is a plan view of the improved pillars constructed by the conventional construction method, and Fig. 11 is a plan view of the modified pillars constructed by the conventional construction method in the vicinity of the inside of the steel sheet pile. It is a top view constructed by circumscribing. 1, 5, 7, 21 ... Rod, 2, 22 ... Excavation blade, 3, 23 ... Stirring blade, 4, 24 ... Low pressure outlet, 6, 8a, 25 ... High pressure outlet, 10a, 10b , 26 …… Improvement pillar, 26a …… Center improvement pillar, 26b …… Outside improvement pillar.

Claims (2)

[Claims] 1. A ground improvement method using a combination of a stirring blade and high-pressure injection, which comprises a combination of the following steps. One-stage drilling blade near the tip and at least one above it
While the pressure at the pump discharge side from the low pressure discharge port provided in the vicinity of the rod lower end while rotating the rod with a stage stirring blade ejects consolidated material of 1kg / cm ² ~15kg / cm ² below the ground to a predetermined depth The step of feeding the rod, while rotating the rod, without discharging the solidified material from the low pressure discharge port, the pressure on the discharge side of the pump from the high pressure discharge port near the tip of the excavation blade is 50 kg / cm ^{2 to} 300 kg / cm ² The step of pulling up the rod while injecting the solidifying material of 2. A ground improvement method using a combination of a stirring blade and high-pressure jet, which comprises a combination of the following steps. One-stage drilling blade near the tip and at least one above it
While the pressure at the pump discharge side from the low pressure discharge port provided in the vicinity of the rod lower end while rotating the rod with a stage stirring blade ejects consolidated material of 1kg / cm ² ~15kg / cm ² below the ground to a predetermined depth a step of KyuSusumu the rod, the pressure at the pump discharge side from the high pressure discharge port in the vicinity of the drilling blade tip of at least the bottom while rotating the rod while injecting the solidifying material of 50kg / cm ² ~300kg / cm ² rod The pressure on the pump discharge side from the high-pressure discharge port while rotating the rod is 50 kg / cm ^{2 to} 300 kg.
A step of injecting the solidifying material of / cm ² and advancing the rod to a predetermined depth below the ground, a step of stirring and pulling up while rotating the rod without discharging the solidifying material at all.