JPS58156619A - Method and apparatus for ground improvement work - Google Patents

Abstract

PURPOSE:To raise the efficiency of ground improvement by mixing excavated soil and cement with good efficiency by a method in which excavation is made while jetting air from the tip of an earth auger and cement is sent under pressure while inversely turning the auger. CONSTITUTION:An earth auger 6 is set on the ground's surface, and high-pressure air is jetted from the hole 21 of a nozzle 20 at the tip of the auger 6 so as to reduce frictional resistance during the excavation of pit. In this case, air is discharged to the ground's surface through the groove 15 of a shaft 13. When boring is made to a given depth, cement is sent under pressure through the pathway 16 of the shaft 13 while inversely turning the auger 6, jetted into the pit from the nozzle 20, and mixed with excavated soil. When the rise of the auger 6 is made smaller than the pitch of a screw 14, the excavated soil is consolidated and mixed with cement at the same time.

Description

[Detailed description of the invention]

The disclosed technology belongs to the field of improvement technology based on air pressure injection of cement, sand, etc. to soft ground. Accordingly, the invention of this application involves screwing an earth auger into a hole in soft ground, etc., and pumping powder such as cement through the passage inside the earth auger with gas such as air at a predetermined depth to form the tip of the earth auger. This invention relates to a ground improvement method in which the ground auger is injected into the borehole from the ground, and the earth auger is pulled up in reverse to stir and mix with the excavated soil to hydrate and solidify the water content in the ground, and a device directly used for the same. In particular, a stirring blade is integrally provided at the tip of the earth auger to crush the ground and drill the hole, and during this time the drilling is assisted by the gas fed inside the earth auger. After reaching a predetermined depth, the gas pumping is switched to the gas pumping of powder such as cement, and the earth auger is pulled up in reverse rotation to push the crushed soil downward between the earth auger blades into the excavated hole, and the stirring blades are used to collect the powder. A soil improvement method in which the earth and soil are uniformly stirred and mixed, and the transported gas is dissipated from the gas vent hole at the base of the stirring blade to the ground through the gas vent groove provided along the shaft of the earth auger, and directly thereto. This invention relates to a device to be used. As is well known, various methods have been devised and adopted as consolidation improvement methods for soft ground, but soft ground usually has a water content ratio of 100%, making it extremely weak. The injection method has the opposite disadvantage of adding liquid into the ground, and in addition, there are pollution problems such as groundwater contamination due to the chemical solution, which has become a trap that limits its use and development. To deal with this, powder improvers such as cement and quicklime are injected into the ground to hydrate it with moisture.
Housing techniques have begun to be developed. Therefore, the old method of ground improvement using powder such as Chemiyuvail and sand drain is a method of transporting the powder using a casing pipe guide, and since it is a direct filling method, it has the disadvantage that it cannot be mixed with the ground. In addition, if the depth is deep, there is a drawback that the powder cannot be reliably filled and transported. Recently, cement and other powders have been transported using gas such as air.
- Actively forms an improved area by mixing and stirring with the soil in the borehole,
Techniques for forming a uniform mixed layer have been devised one after another. In order to drill a hole and inject powder into the ground, for example, as shown in Japanese Patent Publication No. 14808/1980, ground improvement is carried out by using an earth auger and ejecting air-transported cement from its tip. A construction method has been devised. However, although the drilling injection agitation using a nuclide earth auger has an advantage in drilling, the earth auger itself has almost no ability to stir and mix the powder, and therefore, it is not an improvement even though the amount of powder injection is large. It has the disadvantage of poor accuracy and high cost. On the other hand, the agitating blade drilling method has a large agitation effect, but has the disadvantage that it is difficult to compact the mixed soil. The purpose of the invention of this application is to solve the problems of ground improvement by powder injection based on the above-mentioned prior art, and
A stirring blade is used to drill holes in the ground to be improved, crush the ground, and mix the crushed soil with the crushed soil by pumping powder gas.The stirring blade effectively suppresses the downward movement of the earth auger by rotating the earth auger in the opposite direction. An object of the present invention is to provide an excellent powder injection ground improvement method that is guided to the ground through a gas escape groove of an earth auger shaft and is useful in the field of ground improvement application in the construction industry, and a device that can be directly used in this method. It is. The structure of the invention of this application in accordance with the above-mentioned purpose is to rotate a shaft, crush the ground while injecting gas with a stirring blade at the tip, and drill a hole into the ground.An earth auger is screwed into the ground, and when a predetermined depth is reached. Gas pressure delivery. gas! Instead of transporting powder such as cement by transport, the shaft is rotated in the opposite direction and pulled up.

[The earth auger pushes the crushed soil between the auger blades downward, and the powder and stirring blades mix it uniformly, reducing the gap and eliminating the interstitial gas (
However, the main point is that technical measures were taken to ensure that the transported gas exits from the gas vent hole at the base of the stirring blade and is discharged into the ground-F through the gas vent groove on the side of the shaft, separating it from dust and dissipating it into the atmosphere. It is something to do. Next, embodiments of the invention of this application will be described below with reference to the drawings. 1 is a ground improvement device which constitutes one of the gist of the invention of this application, and a swivel joint 5 is attached below a motor 4 of a static load applying and driving device provided on a leader 3 of a heavy machine 2.
The earth auger 6 connected to the unit joint is connected to the lower side. On the other hand, the trolley 7 attached to the heavy equipment 2 has a control value f18.
．． Compressor9. High pressure air tack 10 as a high pressure gas tank connected to the compressor 9. A hose is connected to a hopper 11 for supplying cement as powder, and a transport hose 12 as a gas transport hose is connected from the hopper 11 to the sweep joint 5. As shown in FIG. 2, the earth auger 6 consists of a shaft 13 and a single-threaded screw 14 integrally formed around the shaft. An air (gas) vent groove 15 with a rectangular cross section that is not blocked by the screw 14 is formed, and a gas pumping powder passage 16 connected to the swivel joint 5 is provided inside. At the lower end of the shaft 13, a pair of stirring blades 17.17 having a substantially C-shaped cross section are attached to the side in the diametrical direction at a set distance from the lower end of the screw 14 of the auger 6. An air vent hole 18 connected to the air vent groove 15 is formed in each of the holes. Further, at the lower end of the stirring blade 17, there is a crushing blade 19.19°19.
... is formed. On the other hand, inside the stirring blade 17, the gas pressure-fed powder
An injection nozzle 20 connected to the body passage 16 is integrally fixed to the shaft 13 with nozzle holes 21, 21, . Reference numeral 22 denotes a dust removal cover, and a hood 26 is rotatably fitted in a sealed manner on a plate 25 placed on the top of the hole 24 in the ground 23, and the upper cover 27 has the above-mentioned soyaf,
An insertion hole 28 of the ground auger 13 and an insertion slit 29 for the screw 14 of the earth auger 6 are formed, while an insertion hole 28' and an insertion slit 29' are formed in the bottom cover 27'. Further, only the insertion hole 28 of the shaft 13 in the upper lid 27 has a seal slider 30 coated with Teflon on the inside to fit into the air vent groove 15 of the shaft 13, as shown in FIGS. It is clamped and engaged with the upper lid 27 of the dustproof cover 22, and is configured to slide around the hole 28 as the shaft 13 rotates, thereby sealing the air vent groove 15. Further, a pipe 32 is connected to a swivel joint 31 provided on the hood 26 of the dustproof cover 22 to connect the hood 26.
The underflow pipe 35 of the cyclone 34 is connected to the dust collector 36, and the overflow pipe 37
is open to the atmosphere. A pinion 39 of a reversible motor 38 with a speed reducer provided on the chassis of the heavy equipment 2 meshes with a gear 40 provided integrally around the side surface of the rotary hood 26, thereby aligning the hood 26 with respect to the plate 25 of the dustproof cover 22. Allows for reverse rotation. When performing ground improvement using the device configured as described above, only the stirring blade 11 and the unit earth auger 6 at the tip are used to dig in advance into the predetermined ground 23 without the dustproof cover 22 set.
The next unit earth auger 6 is inserted into the insertion hole 28, 28' and the insertion slit 29, 29' of the dustproof cover 22, the seal slider 30 is engaged with the air vent groove 15, and the reversible motor 38 is stopped, that is, The hood 26 is not rotated, but is connected to the leading earth auger 6 in a predetermined manner, and the shaft 13 is rotated in the forward direction while static pressure is applied by the motor 4, and a valve (not shown) is closed to close the cement supply hopper 11.
Close the high pressure air tank 10 and connect the high pressure air to the hose 1.
2 and the swivel joint 5 to the injection nozzle 20 of the stirring blade 17 from the passage 16. Then, a hole 24 is formed in the ground 23 by normal rotation of the shaft 13. In this case, the stirring blades 17 are crushing the ground 23, and the high-pressure air injected from the nozzles 21, 21, etc. of the injection nozzles 20 assists in drilling and crushing by reducing friction. The air used for the assistance passes through the air vent hole 18 from between the injection nozzle 20 and the stirring blade 17 and rises from the air vent groove 15 of the shaft 13, and then passes through the air vent groove 15 of the dust cover 22 and the air vent groove 15. It passes through and enters the dustproof cover 22. Inside the dustproof cover 22, the air ejected from the top lid 27 separates the dust by gravity, passes through the exhaust hole 32, the vibrator 33, and the cyclone 34 to separate the fine powder, and the air component is dissipated into the atmosphere. . In addition, for the air vent groove 1% of the shaft 13 inside the dustproof cover 22, a seal slider 30 is inserted into the insertion hole 28 in the upper cover 27.
are engaged, so air and dust are not discharged outside and do not pollute the environment. Therefore, the air supplied during the drilling process is for drilling assistance, and as far as that is concerned, the used air is sent to the earth auger 6.
The air is returned to the ground from the air vent groove 15 of the shaft 13 and is dissipated to the ground, so that no sound pressure is generated in the borehole 24, and therefore the pressure inside the borehole is increased.
This invention is completely different from the invention disclosed in the publication. Further, since the shaft 13 is rotated at a considerable angular velocity, soil and water are prevented from entering the air vent groove 15, and air bleeding is guaranteed. When the set depth is reached, the motor 38 is rotated at the set speed, and the pinion 39. The hood 26 of the dustproof hood 22 is reversely rotated with respect to the plate 25 via the gear 40, and the motor 4 is reversely rotated to reverse the shirt 13 to open the rotary pulp (not shown) of the cement supply hopper 11 and the hose 12 The injection nozzle 20 of the stirring blade 17 is connected to the passage 16 through the swivel joint 5.
Air pump the cement to the In this case, the earth auger 6 reverses and rises due to the reversal of the shaft 13, but since the hood 26 of the dustproof cover 22 is rotated in the circumferential direction to provide a set relative angular velocity difference, the earth auger 6 is ground. The rising speed of the shaft 13 is set to be slower than the rotation speed of the screw 140 compared to when drilling, so that the screw 14 of the earth auger 6 presses down the crushed and agitated soil clamped in the hole 24. to work. Therefore, the crushed and agitated soil in the borehole 24 during drilling is compressed and mixed with the cement jetted from the injection nozzle 20 by the ascending stirring blades 17, making it uniform and dense. During this time, the transported air and the gap air due to compression enter the dust cover 22 through the air vent hole 18 of the stirring blade 17, the air vent groove 15 of the shaft 13, and the dust is separated by gravity, and further separated by the cyclone 34. The air is released into the atmosphere and no pollution of the working environment occurs. Then, as the earth auger 6 rises, the screw 14
The adhering soil will be scraped off by the insertion slit 29' of the plate 25 of the dustproof cover 22 and will not enter the dustproof capacity ζ-22. In this way, the earth auger 6 and stirring blade 17 are gradually lifted up, and a homogeneous mixed structure of the drilled crushed agitated soil and cement is formed in the drilled hole 24, and over time, groundwater,
It hardens through a hydration reaction with water-containing substances. Then, the dust cover 6 is removed from the tip unit earth auger 6 and stirring blade 17 to complete the work. It is needless to say that the embodiments of the invention of this application are not limited to the above-mentioned embodiments. For example, instead of connecting a cyclone to the dustproof cover, a bag filter may be connected,
Various methods can be adopted, such as using quicklime, sand, etc. instead of cement. As mentioned above, according to the invention of this application, when improving the ground using powder, drilling is performed with a stirring blade assisted by gas injection, and when drilling the hole, the ground is primarily ground by the stirring blade. After the ground auger has been crushed and stirred at a predetermined depth, the earth auger screwed in is pulled up and rotated in the opposite direction, and the stirring blades are also rotated to eject 1-n scum transport powder. By doing so, the primary crushed and agitated soil held between the screws by the earth auger is suppressed and lowered, and is secondarily evenly stirred and mixed with the powder by the agitating blade, and is uniformly and A compact structure is formed, which is hydrated with underground moisture to form a coagulated body, which provides an excellent effect. Therefore, no unstirred parts or non-uniform parts are generated in the structure, and the excellent effect of increasing the precision of the improved area is achieved. Further, in this case, there is an effect that the compaction state can be adjusted by adjusting the rotational speed and pulling speed of the earth auger. Since the device has a structure in which a stirring blade is connected to a screw auger, the device is simple in structure, robust, and durable. In addition, since a stirring blade is attached to the tip of the auger screw, there is little resistance to screwing in the earth auger during drilling, and the stirring blade has the effect of pressing down the crushed soil during the lifting process. In addition, the gas vent hole provided at the base of the stirring blade is connected to the gas vent groove provided on the axial side of the shaft, allowing the gas to escape to the ground during powder feeding during drilling and into the drilling hole. The excellent effect of not leaving gas behind or forming voids in the constructed body and improving the construction accuracy is achieved.

[Brief explanation of the drawing]

The drawings are detailed explanatory drawings of the invention of this application, and Fig. 1 is an overall schematic explanatory drawing, Fig. 2 is a partially enlarged view of Fig. 1, Fig. 3 is a partially sectional view of the earth auger, and Fig. 4 is a dustproof cover. FIG. 5 is a perspective view, FIG. 5 is a partial sectional view of the same, and FIG. 6 is a sectional view of the dustproof device. 6...Earth Olga, 23...Ground, 24...
Hole drilling, 17... Stirring blade. 16... passage, 20... injection nozzle, 18
...Gas vent hole, 13...Shaft, 15...
・Gas vent groove

Claims (2)

[Claims] (1) An earth auger is screwed into the ground, and gas is ejected from its tip to drill a hole with gas assistance to a predetermined depth.Then, the earth auger is pulled up in reverse and powdered gas is pumped into the ground. In the ground improvement method in which the earth auger is mixed with the ground, the earth auger is screwed into the hole by drilling the ground while injecting gas with a stirring blade prior to the earth auger, and then the earth A ground improvement method characterized in that the crushed soil pressed down by the earth auger in the auger pulling process is stirred and mixed with gas-fed powder using the stirring blade. (2) In a ground improvement device having an earth auger with a gas and gas-forced powder passage therein, a stirring blade is integrally provided at the tip of the earth auger, and a gas and gas-forced powder injection nozzle provided on the stirring blade are provided. is connected to the gas and the gas pumping powder passage, and the gas vent hole provided at the base of the stirring blade is connected to the gas vent groove extended on the side surface of the shaft of the earth auger. Ground improvement equipment.