JPH0424488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for hardening soft ground in swamps, rivers, coasts, etc. to strengthen the ground.

In the conventional soft ground improvement method, ground hardening agents such as cement and quicklime are mixed with water using ground equipment.
A common method was to make a slurry, pump it to a stirring blade buried in soft ground, and pour it out from the stirring blade. In addition, in recent years, a construction method has come into use in which the ground hardening agent is not made into a slurry, but instead is air-fed in the form of a powder, and is injected into soft ground together with air from an agitating blade. However, in the former slurry pressure injection method, smooth transportation and uniform dissolution cannot be achieved unless the water/cement volume ratio is around 1:1 to 1:2. Moreover, since soft ground contains water, if the cement slurry poured into soft ground mixes with the soft ground, it will become even more water-rich and the strength of the ground will decrease even if it hardens. Furthermore, the cement slurry hardens in the pipe when not in use, clogging the pipe and rendering it unusable. In addition, in the latter powder type injection method, when the transported air rises and leaves the soft ground and is released to the ground, it also carries the powdered ground hardening agent, which spreads on the ground and deteriorates the ground environment along with the air. In addition, there was a problem in that the ground hardening agent sprayed in powder form could not be sufficiently dissolved in the water of the soft ground, resulting in agglomeration and a decrease in the strength of the ground.

The present invention aims to provide a method for improving soft ground hardening based on a new concept that eliminates such problems.

The gist of the present invention is to pneumatically transport a soil hardening agent in powder form from a ground device to a stirring blade embedded in soft ground, and also to transport water from the ground side to the stirring blade, and to agitate the water from the stirring blade. The powdered ground hardening agent is injected toward the soft ground space behind the rotation direction of the blade to form a water film or a water barrier, and the powdered ground hardening agent is transported to the stirring blade to form a water film or water. It is injected together with transport air from the inside of the barrier wall to the outside, collides with the water film or the water barrier, and upon contact, instantly dissolves the ground hardening agent in the water and passes through it in a jelly-like or muddy state. This is a method for improving soft ground, which is characterized by mixing it into soft ground and hardening it by mixing it with a stirring blade. Examples will be described below based on the drawings.

Figure 1 is an explanatory diagram showing the working status of the soft ground hardening improvement method, Figure 2 is a front view showing the stirring blade part,
Figure 3 is a plan view of the same, Figure 4 is a sectional view taken along the line shown in Figure 3, Figure 5 is an explanatory diagram showing the relationship between the rotating shaft of the stirring blade and the air discharge pipe, and Figure 6 is the injection nozzle section. FIG. 7 is an explanatory diagram showing another injection nozzle portion. In the figure, 1 is the stirring blade, 2 is the rotation shaft of the stirring blade, 3 is the injection nozzle, 4 is the soil hardening agent transport pipe, 5 is the water pipe, 7 is the water injection nozzle, 8 is the annular water storage chamber, and 9 is the injection nozzle. 3
recovery air discharge conduit for transport air injected from the 10
11 is a water pipe attached to the outside of the blade; 12 is a hollow key pipe for rotational driving installed in the axial direction of the rotating shaft; 13 is a work hull; 14
15 is a water supply device, 16 is a generator, and 17 is a rotating lifting support device for the rotating shaft 2.

In this embodiment, a ground hardening agent such as cement or quicklime is air-transported in a powder state by a ground device, and is transported to the stirring blade 1 through a soil hardening agent transport pipe 4 in the rotating shaft 2. The soil hardening agent is sent to the injection nozzle 3 via the ground hardening agent pipe 10 in the container. At the same time, water is sent from the ground side to the stirring blade 1 through the water pipe 5 in the rotating shaft 2, and then to the water pipe 11.
The water is sent to the water injection nozzle 7 through the water injection nozzle, and the water forms a conical water film from the rear end of the stirring blade 1 toward the rear space of the stirring blade hollowed out by the rotating stirring blade 1. It is injected in a state that On the other hand, the soil hardening agent sent to the injection nozzle 3 is injected from the injection nozzle 3 toward the conical water film with air at a high velocity. When the ground hardening agent passes through this conical water film, the powdered ground hardening agent instantly collides with the water and dissolves into a jelly-like or mud-like form that passes through the conical water film. It is thrown into the soft ground, mixes into the soft ground, and is stirred and mixed by the stirring blade 1.
The soil hardening agent is uniformly and completely dissolved and mixed into the soft ground. Since the ground hardening agent in the air transported to the injection nozzle 3 becomes jelly-like due to water injection, it does not contain powdered ground hardening agent even if it is ejected from the injection nozzle 3. Then, the ejected air is sucked through the opening of the air discharge conduit 9 installed in the vicinity of the injection nozzle 3, and is sent through the air discharge conduit to the hollow key tube 12 which becomes the key of the rotating shaft. It is then released to the atmosphere on the ground.

Here, the amount of water to make the powdered ground hardening agent into a jelly form is 1:0.1 in water to cement volume ratio.
It only takes ~0.2, which is 1:1 compared to the conventional slurry type.
Compared to 1:2, primary dissolution can be performed with a much smaller amount of water, and it is mixed into soft ground and stirred after being dissolved into a jelly-like or mud-like form, making it easy to mix with soft ground. Moreover, it is done uniformly. Furthermore, since only a small amount of water is required, the strength of the hardened ground can be increased several times without overwatering, and the hardening process can be accelerated. Since the moisture content is easy to adjust, it can be widely used in both soft ground with a lot of moisture, such as ultra-soft ground, and soft ground with little moisture. Furthermore, since the powdered ground hardening agent becomes jelly-like or muddy in the hollow space of the soft ground away from the injection nozzle, the injection nozzle, the ground hardening agent transport pipe 4, etc. will never be clogged. FIG. 7 shows various other embodiments in which the jetted water forms a water film or a water barrier in a hollow space of soft ground.

As described above, according to the present invention, the following excellent effects can be obtained.

(B): A powdered ground hardening agent is injected from an injection nozzle, collides with the water film or water barrier formed by the injected water in the soft ground, and dissolves with the injected water to form a jelly-like or Since it is mixed into the soft ground in the form of mud, it is mixed uniformly and quickly with the soft ground without forming lumps.

(B): Because the ground hardening agent instantaneously becomes jelly-like or muddy, the air released upward with the injection does not contain the powdery ground hardening agent, and the powdery ground is formed by releasing the air into the atmosphere. The curing agent will not scatter and contaminate the ground environment.

(c): Since the amount of water sprayed from the injection nozzle to make it into a jelly-like or mud-like state is small, it is possible to achieve an optimal water-cement ratio with a small proportion of water, and to ensure sufficient ground strength. .

(d): In addition, it is possible to easily adjust the optimal ratio of soil hardening agent and water according to the water content of the soft ground, so that optimal hardening improvement work can be carried out for various types of soft ground.

(E): The powdered ground hardening agent is air-pneumatically delivered from the injection nozzle in powder form until the end, so the ground hardening agent does not get clogged in the injection nozzle or in the middle of the transport pipe, allowing stable ground hardening improvement work.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the soft ground hardening improvement method of the present invention, Fig. 2 is a front view showing the stirring blade used in the present invention, Fig. 3 is a plan view of the same, and Fig. 4 is Fig. 3-
5 is an explanatory diagram showing the relationship between the rotating shaft of the stirring blade and the air discharge conduit, FIG. 6 is a sectional diagram showing the injection nozzle portion, and FIG. 7 is an explanatory diagram showing the other injection nozzle portions. It is a diagram. 1: Stirring blade, 2: Rotating shaft, 3: Injection nozzle, 7: Water injection nozzle, 13: Working hull.

Claims (1)

[Claims] 1 Pneumatically transports the soil hardening agent from the ground equipment to the stirring blades embedded in the soft ground in powder form, and also supplies water from the ground side to the stirring blades, so that the water is transported from the stirring blades to the stirring blades in the direction of rotation of the stirring blades. The powdered ground hardening agent is injected towards the rear soft ground space to form a water film or water barrier, and the powdered ground hardening agent is transported to the stirring blades from inside the formed water film or water barrier. injected outward with transport air,
Upon collision and contact with the same water film or water barrier, the ground hardening agent is instantly dissolved in water, passes through in a jelly-like or mud-like state, mixes into the soft ground, and is hardened by being kneaded with a stirring blade. A soft ground improvement method characterized by