JPH09125367A - Dry type ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform mix density of improvement additive despite of deep or shallow ground depth without spoiling superior points of a conventional dry method. SOLUTION: A casing tube 30 set in a press-in device is adjusted in a pile core position of a soft ground, the press-in device is erected on the ground, an agitating rod 40 provided with a leader 2 is screwed in the ground in the adjacent to the pile core position, and the casing tube 30 is pressed in by the press-in device, while using the reaction of this screwed agitating rod 40. The improvement additive which is put in the casing tube 30 is grouted in the ground into a column shape from the tip of the casing tube 30 by drawing-out action of the casing tube 30, the agitating rod 40 is inversely rotated so as to be drawn out, the agitating rod 40 moved to the pile core where the improvement additive is put in is screwed, normally/inversely rotated, and cuts while mixedly agitating, and when it cuts to the prescribed depth, the agitating rod 40 is inversely rotated so as to be drawn out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry ground improvement method for stabilizing and strengthening the ground by mixing and agitating a powder or granular improvement additive with soft ground.

[0002]

2. Description of the Related Art Various scientific ground improvement methods have been proposed and developed in order to stabilize and strengthen the ground by mixing and agitating a soft ground with an improved additive. In addition, this scientific ground improvement method has made great strides with the recent development of excellent construction machines and materials, and is widely used in various civil engineering and construction works. Generally, the improved additive used by mixing and stirring with soil is
There are two cases: when it is used by dissolving it in a liquid (the method using this is called the wet improvement method) and when it is used as powder or granules (the method using this is called the dry improvement method). Broadly divided.

[0003]

In the former wet improvement method, the one generally called cement milk method is generally used. However, for example, various facilities such as a plant, a generator, a water tank, and a water supply are inevitable. Since it is indispensable, there is a problem that the construction space is large and the transportation cost and maintenance cost are high. In addition, the following inconveniences also occur in this wet improvement method. Slow construction speed and inefficiency, waste soil treatment and drainage of wastewater, plant operation personnel required, a large number of workers required, groundwater contamination due to infiltration into the ground There is a risk of this, and construction costs will increase significantly.

On the other hand, the dry improvement method can eliminate the drawbacks of the wet method enumerated here, and can reduce the water content in the soil to stabilize the soil quality.
Especially, it is effective for high hydrous soil. However, with this dry improvement method, it is difficult to evenly mix the improved additive material into the ground soil to be improved, and the mixing ratio tends to decrease as the soil deepens.

In view of the above-mentioned circumstances, the present invention provides a dry ground having a uniform mixed concentration of the improved additive regardless of the depth of the soil and having the advantages of the conventional dry improved method. It is intended to provide an improved method.

[0006]

[Means for Solving the Problems] That is, according to the invention of claim 1, after injecting a powder or granular improving additive into soft ground, the injected improving additive is mixed and stirred to mix the ground. It is a dry ground improvement method for improving the stability of the soil, and after the casing tube set in the press-fitting machine installed in the leader of the erecting pile driving device is press-fitted into the soil, the improvement additive is added to the soil. A stirring rod provided in parallel with the casing tube is screwed into the portion to rotate forward and backward to uniformly stir the improved additive material, thereby stabilizing the ground.

[0007]

An embodiment of the present invention will be described below with reference to the accompanying drawings. In this embodiment, first, a dry ground improvement apparatus used in the dry ground improvement method of the present invention will be described. 1 and 2 are a side view and a front view showing a dry ground improvement apparatus according to the present invention. This dry ground improvement device includes a device main body 1 provided with a cockpit 1A and an outrigger 1B, a long substantially box-shaped reader 2 standing upright on the device main body 1 (having a substantially H-shaped cross section), and this reader 2. On both sides (eg 50 cm to 1 in this embodiment)
The press-fitting mechanism section 3 and the excavation mechanism section 4 are installed. The details of each part constituting this dry ground improvement device are the same as those described in the pile driving device already filed by the same applicant and in the 1995 patent application No. 44912 filed on Feb. 9, 1995. Please refer to this because it is almost the same.

The press-fitting mechanism section 3 is configured to drive a substantially cylindrical casing tube 30 (see FIG. 3) arranged in the leader 2 with a hydraulic press-fitting machine (see FIG. 3) 31. The casing tube 3 shown in FIG.
0 is a valve 30 that opens and closes by being divided into two at the tip from the center
A is provided so that when it is pulled up from the soil to the upper side, it is naturally released by the action of gravity and the action of pressure by the improved additive material introduced inside. Further, a vibrator 32 (see FIG. 5) is attached to the lower portion of the press-fitting machine 31, so that the improved additive inside the casing tube 30 can be easily extracted from the casing tube 30.

The excavation mechanism section 4 is provided on the side of the leader 2 opposite to the casing tube 30 and is oriented in various directions.
The stirring screw 40 (see FIG. 7) provided with 0B is rotated by a hydraulic motor 41 so as to be freely reciprocal. The stirring screw 40 shown in FIG. 7 is provided with a bit 40A having a radius dimension D larger than the outer diameter dimension d of the casing tube 30 at the tip portion, and the improvement additive is soiled by rotation of the bit 40A and the blade 40B. And mix with stirring.

Next, a dry ground improvement method according to the present invention will be described with reference to the drawings using the dry ground improvement apparatus of this embodiment. First, in the lakeshore, coastal marshes, and other soft ground G having an N value of about 5 or less, which is to be improved as shown in FIG. 1, the outrigger 1B firmly fixes the apparatus main body 1 that has moved near the desired pile core position.・
After stabilizing, it was laid down horizontally (dashed line)
The leader 2 is erected by, for example, the erection / rotation mechanism 5. In other words, the outrigger 1B and the reader 2 stand upright on the ground in a stable state. Then, by using a winch (not shown) attached to the press-fitting machine 31 provided on one side of the reader 2, after the casing tube 30 is lifted and set to the standing state, as shown in FIG. Stand upright at the pile core position.

Next, a stirring rod 40 (FIG. 7) which is installed in parallel with the casing tube 30 and stands upright on the other side of the leader 2 is screwed into the ground to prepare for reaction force when driving the casing tube 30. I'll do it.

Next, the casing tube 30 is pressed into the ground by the press-fitting machine 31. The press-fitting action at this time can be efficiently and promptly performed by utilizing the gravity of the press-fitting machine 31 and the casing tube 30 itself as well as the reaction force of the stirring rod 40.

In this way, the casing tube 30
When the tip of the powder reaches a predetermined depth, as shown in FIG. 4, an appropriate improvement additive material (in the form of particles or powder) 6
Hopper 33 provided with the casing tube 30 on the upper side thereof
Then, it is gradually fed into the inside of the hollow casing tube 30.

When the amount of the improved additive material 6 reaches the specified value, the addition is immediately stopped and the casing tube 30 is pulled out by the press-fitting machine 31, as shown in FIG. The valve 30A provided at the tip of the casing tube 30 automatically opens, and the improved additive material 6 comes out from the opened tip. In this way, when the casing tube 30 is pulled out from the ground, as shown in FIG. 6, the improved additive material 6 is injected and formed in the ground in a columnar shape, and remains. In addition, at the time of the pulling-out work here, by operating the vibrator 32 attached to the press-fitting machine 31 to vibrate, the improved additive material 6 can be quickly and reliably separated from the casing tube 30.

Next, if the stirring rod 40 previously used for the reaction force removal is reversed by the hydraulic motor 41 and pulled out from the ground, the standing rotation mechanism 5 slightly rotates the leader 2 ( The stirring rod 40 is moved to the pile driving position at an angle such that it can be moved by the distance between the casing tube 30 and the stirring rod 40 (for example, about 10 to 20 degrees). Then, after the stirring rod 40 is aligned with the pile core position, the hydraulic motor 41 is normally rotated and screwed into the ground as shown in FIG. 7. Thus, when the bit 40A at the tip of the stirring rod 40 reaches a predetermined depth, the blade 40B is rotated by rotating the hydraulic motor 41 in the forward and reverse directions to evenly mix and stir the improved additive material 6.

When the improved additive material 6 is uniformly mixed and stirred, the hydraulic motor 41 is reversed and the stirring rod 40 is pulled out from the ground to complete the stirring operation. As a result, as shown in FIG. 8, in the desired ground, the piles 6'having a uniform mixed concentration depending on the depth, that is, having a substantially uniform strength.
Can be a pillar. In addition, to the next place
You can move the, and repeat the same work to build the same pile in the ground in other places.

[0017]

As described above, according to the present invention, the stirring tube is screwed into the underground portion into which the improved additive is introduced after the casing tube is press-fitted, and the stirring rod is rotated forward and backward to improve. Since the additive material can be evenly stirred, it not only has the excellent features of the conventional dry ground improvement method, but also has a uniform and uniform depth that is difficult to achieve in the conventional dry method. The stirring / mixing action can be performed reliably and quickly, and a low-cost, high-quality dry ground improvement method can be provided.

[Brief description of the drawings]

FIG. 1 is a side view showing a dry ground improvement device used in the present invention.

FIG. 2 is a front view.

FIG. 3 is an explanatory view showing a dry ground improvement method of the present invention.

FIG. 4 is an explanatory view of the same.

FIG. 5 is an explanatory diagram of the same.

FIG. 6 is an explanatory view of the same.

FIG. 7 is an explanatory view of the same.

FIG. 8 is an explanatory view of the same.

[Explanation of symbols]

 1 Device Main Body 2 Leader 30 Casing Tube 31 Press Fitting Machine 40 Stirring Rod 41 Hydraulic Motor 6 Improved Additive

Claims (1)

[Claims] 1. After injecting a powder or granular improving additive into soft ground, mixing the injected improving additive.
A dry ground improvement method that stirs and strengthens the ground stability.The casing tube set in the press-fitting machine installed in the leader of the erecting pile driving device is pressed into the soil, and then the additive is added. In the soil part that has been prepared, the stirrer rod provided in parallel with the casing tube is screwed in and rotated forward and backward to evenly stir the improved additive material to stabilize and strengthen the ground. Dry ground improvement method.