JPH0554537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to an injection device for injecting an injection material into the ground to improve the ground.

<<Background of the invention>> The high-pressure injection injection method is a type of ground injection method, in which a cement milk or other injection material is injected at high pressure through a nozzle to cut the ground, and the soil particles and the injection material are mixed and stirred to form a solidified material. This is a construction method in which the soil is created in the ground.

One of the characteristics of this method is that dynamic pressure is applied to the injection material to perform ultra-high-pressure injection, and by providing directionality to the injection, a uniform column-shaped or wall-shaped solid body can be created in the target area. There are things you can do.

However, the injection device for the injection material used in the conventional construction method of this type has the following problems.

<<Problems to be solved by the invention>> In other words, in order to create a good consolidation material using the above construction method, it is generally necessary to increase the concentration of the injection material, although this varies depending on the properties of the ground. .

However, conventional injection devices supply the injection material in the form of a slurry, so the higher the concentration, the more
There were problems in that high pressure was required to pump this, the pressure pump became large, and the pressure pump was also subject to significant wear and tear.

This invention was made in view of these conventional problems, and its purpose is to:
To provide a soil improvement injection device that does not cause the size of a pressure pump to increase even when the concentration of injection material is high, and has low wear and tear.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides an injection shaft in which a consolidation material transport pipe is arranged concentrically around the outer periphery of the high-pressure water transport pipe, and an injection shaft provided at the tip of the injection shaft. A drilling bit connected to each of the transport pipes, and a high-pressure water spout hole provided at the high-pressure water supply end and the tip of the drilling bit within the drilling bit, so that the supply pressure of high-pressure water is higher than a predetermined level. a pressure-sensitive shutoff valve mechanism that closes the ejection hole when the ejection hole is reached; an orifice for forming a jet flow that opens from the high-pressure water supply end to the consolidation material supply end side perpendicular to the axial flow direction of the high-pressure water; and the drilling bit. It consists of a jet nozzle opening coaxially with the orifice toward the outer periphery of the orifice.

<<Operation>> Due to the ejector effect of the jet stream of high-pressure water ejected from the orifice, a negative pressure is created inside the consolidation material supply end, and the consolidation material is jetted together with high-pressure water toward the outside of the drilling bit.

<<Example>> Hereinafter, an example of the present invention will be described in detail using the drawings.

Fig. 1 is an explanatory diagram showing the overall structure of the device of this invention and the construction order using the device, Fig. 2 is a sectional view showing the tip of the drilling bit of the device, and Fig. 3 shows the orifice portion of the drilling bit. It is a partially enlarged view.

Among the figures, especially FIG. 1a shows the entire structure of the apparatus.

This device is a caterpillar driven base machine 1
, a vertical guide 2 provided at the tip of the base machine 1 so as to be able to stand upside down, an injection shaft 3 supported so as to be rotatable and movable up and down along the vertical guide 2, and a vertical guide 2.
A drive motor 4 for rotationally driving the injection shaft 3 and a conical drilling bit 5 provided at the tip of the injection shaft 3 are provided at the lower part of the injection shaft 3. The upper end of the injection shaft 3 is connected to a swivel 6, and its center is connected to a water tank 7 located near the excavation position and a silo 8 containing powdered solidifying material such as cement.
is connected to.

The water tank 7 and the silo 8 each have a valve 9,
10 is connected, and a pump P for high-pressure water injection is provided in the supply path of the water tank 7.

Note that the silo 8 may be provided with a compressor for supplying the consolidation material into the supply path.

The injection shaft 3 is a double hollow tube, with an inner cylinder serving as a high-pressure water transport pipe, and an inner peripheral portion of the outer cylinder serving as a consolidating material transport pipe.

Accordingly, the upper part of the drilling bit 5 has a double concentric shape as shown in FIG. A communication hole 52 formed between the peripheral edge and the outer circumferential cylindrical portion 5a of the drilling bit 5 is connected to the consolidation material transport pipe side.

In addition, a high pressure water spout hole 5 is provided at the lower end of the drilling bit 5.
3 is formed as an opening, and this jet hole 53 is connected to a supply end 51a which has a smaller diameter than the central flow hole 51.
is connected to. A pressure-sensitive shutoff valve mechanism 54 is interposed in this communication path, and when the supply pressure of high-pressure water exceeds a predetermined value, this shutoff valve mechanism 54 operates to close the communication path.

The shut-off valve mechanism 54 is located at the periphery of the high-pressure water supply end 51a and is connected to a pressure receiving chamber 5 formed at the lower part of the partition wall 55.
6, and a valve 57 protruding from the center of the pressure receiving chamber 56.
It consists of a spring 58 that always biases the valve 57 toward the open side, and a plurality of passages 60 that connect the funnel-shaped valve seat surface 59 formed on the lower surface of the valve 57 and the ejection hole 53.

The lower surface of the valve 57 has a funnel shape according to the shape of the valve seat surface 59, and a piston 62 and a piston rod 63 are integrated at the lower portion thereof. The piston 62 is slidably housed in a spring chamber 64 formed at the lower center of the valve seat surface 59, and is always supported by the aforementioned spring 58 interposed between this lower portion and the inner bottom surface of the spring chamber 64. It is biased upward. Note that an air venting passage 64a communicating with the ejection hole 53 is opened in the spring chamber 64.

On the other hand, the piston rod 63 passes through a first cavity 65 communicating with the lower part of the spring chamber 64 and the lower part of each passage 60, and projects into a second cavity 66 located directly above the jet hole 53. There is.

Further, an L-shaped passage 67 is formed in the lower part of the piston rod 63, with its lower end facing the jet hole 53 and its side opening into the first cavity 65.

Next, on the upper side of the partition wall 55, an orifice 68 for injection formation is formed at the side of the high-pressure water supply end 51a and penetrates the cylindrical partition wall 5b perpendicular to the axial flow direction. A jet injection hole 69 is opened in the drilling bit 5 and is in communication with the side flow hole 52 and is coaxial with the orifice 68 .

As shown in FIG. 3, the orifice 68 has a support member 72 for forming an orifice attached to a female threaded portion 71 that is threaded continuously into a small hole 70 opening in the cylindrical partition wall 5a. This support member 72
A sapphire drill 73 with an orifice hole 73a is buried on the side opposite to the small hole 70. A through hole 74 is formed in the support member 72 and enlarged at the rear of the sapphire wheel 73.

On the other hand, a carbide chip 75 is embedded in the jet nozzle 69.

As described above, the jewel 73 and the carbide tip 75 prevent the orifice 68 and the jet hole 69 from being worn out.
The required orifice jetting effect can be obtained.

Next, the operation inside the excavation bit 5 having the above structure will be explained.

If water is now supplied to the high-pressure water supply end 51a, the pressure against the upper pressure receiving surface of the valve 57 is generated by frictional resistance in addition to the resistance of the passages 60, 67 and the jet hole 53.

When the water supply flow rate is low, the pressure on the upper pressure receiving surface of the valve 57 is less than the spring pressure of the spring 58, so the valve 57 is in a stationary state.

Then, as the flow rate gradually increases, the spring force becomes responsive, the spring 58 is compressed, and the valve 57 moves downward.

Due to this movement, the passage area of the passage 67 becomes smaller, so the frictional resistance increases, the balance between the spring force and the pressure acting on the upper pressure receiving surface of the valve 57 is lost, and the valve 57 moves downward more and more.
Eventually, the valve 57 will come into close contact with the valve seat surface 59, and the valve 57 will be closed with strong pressure.

If you continue to supply high pressure water in a closed state,
This high-pressure water gradually reaches an extremely high pressure state, passes only through the orifice 68, whose amount has been negligible up until now, passes through the flow hole 52, and jets out through the jet hole 69 to the outside. In this state, when the powder compaction material is supplied to the flow hole 52 side, the flow hole 69 becomes negative pressure due to the engine effect of the ultra-high pressure jet water stream ejected from the orifice 68, and the high pressure jet flow of the compaction material becomes negative. The injection material is then jetted outside as a stirred and mixed injection material. Therefore, by adjusting the supply pressure of high-pressure water, the jet can be injected into the ground of the consolidation material.

Next, this order will be explained using FIG. 1 again.

That is, FIG. 1a shows the excavation preparation state, and the injection shaft 3 is located at the uppermost position.

When the pump P is driven at a low pressure from this state, high pressure water is jetted out only from the spout hole 53 of the drilling bit 5. Therefore, by lowering the motor 4 and swivel 6 while ejecting, the drilling bit 5 is rotated and lowered as shown in FIG. 1b.

In this way, the drilling bit 5 is penetrated to a predetermined depth as shown in FIG. 1c.

From this state, the injection shaft 3 is rotated and raised again as shown in d. In this case, the valve 10 is opened so that the solidified material in the silo can be transferred. When the pump P is driven at high pressure, as described above, due to the closing action of the shutoff valve mechanism 54, the solidified material is jet-injected as an injection material along with water onto the outer periphery of the excavation bit 5, and is stirred and mixed with the ground while cutting the ground. Ru.

In this way, when the injection shaft 3 returns to near the ground surface, the injection material is in the state shown in Figure 1e,
By curing this, a column-shaped solidified body can be obtained.

Now, in the injection device configured as above, the consolidating material and the high-pressure water transport pipe are each separate, so simply adjusting the pressure of the high-pressure water
You can easily change the concentration of the injection material injected into the ground.
Even if the injection material is highly concentrated, the pump for pumping the injection material does not need to be as large as conventional devices of this type.

<<Effects of the Invention>> As explained in detail in the embodiments above, according to the injection device of the present invention, transport energy for transporting the consolidation material is almost unnecessary, and the injection concentration of the injection material can be reduced by pumping. Excellent effects such as easy adjustment can be obtained without increasing the size.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing the overall structure and construction order of the apparatus according to the present invention, and FIG. 2 is a sectional view showing the main parts of the present invention. FIG. 3 is an enlarged sectional view showing the orifice portion. 3... Injection shaft, 7... Water tank, 8... Silo, 5
4... Closing valve mechanism, 68... Orifice, 69...
...Jet vent.

Claims (1)

[Claims] 1. An injection shaft having a consolidating material transport pipe arranged concentrically around the outer periphery of the high-pressure water transport pipe, an excavation bit provided at the tip of the injection shaft and connected to each of the transport pipes, and within the excavation bit, a pressure-sensitive shutoff valve mechanism that is interposed between the high-pressure water supply end and a high-pressure water spout hole provided at the tip of the drilling bit and closes the spout hole when the high-pressure water supply pressure exceeds a predetermined value; a jet-forming orifice that opens from the high-pressure water supply end toward the consolidation material supply end, and a jet nozzle that opens toward the outer periphery of the drilling bit coaxially with the orifice. A ground improvement injection device characterized by: