JP2004068439A - Pressurized liquid injecting head for excavating ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a head for injecting pressurized liquid from a boring hole in order to disperse soil, which is attached to the end of a drill string including a liquid feeding means for feeding the pressurized liquid. <P>SOLUTION: The head includes a body and an outer wall, and the body has at least one injection nozzle installed therein, which has an insertion port with a diameter of d and extends along an axis x-x'. The body further has a duct forming means which has a central line including a first end connected to the lower end of the liquid feeding means and a second end connected to the injection nozzle in a tangential direction with respect to the axis x-x'. The central line is defined by at least one curved portion having a radius of curvature which is continuously varied. The cross sectional surface of the duct forming means is regularly reduced at least one half of its entire length from a first end to a second end. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pressurized liquid injection head for ground excavation, and more particularly to an injection head for implementing a technique known as "jet grouting".
[0002]
[Prior art]
The technique of jet grouting consists in dispersing the soil by a very high kinetic energy liquid jet, which is implemented in a borehole, which erodes the ground to be excavated. To eject the liquid, a nozzle fixed to the end of the drill string is used, and the rod of the drill string carries the high-pressure liquid to the nozzle and simultaneously translates the nozzle progressively in the soil. More precisely, one or more nozzles are fixed to a member attached to the lower end of the drill string, commonly referred to as a "monitor" or "injection head", and the lower end of the monitor itself is fitted with a mechanical boring tool. Arbitrarily fit. Also, as is well known, cement-based slurries are generally used as the liquid to form a cement element that is poured into a predetermined location in the soil after boring.
[0003]
The liquid conveyed by the drill string is delivered from the surface by a pump under a pressure of 10 to tens of megapascals (MPa). The inside diameter of the drill string carrying the liquid must be large enough to minimize head loss in the drill string. Generally, this inner diameter may be between 20 millimeters (mm) and 50 mm. On the other hand, the inner diameter of the outlet from the nozzle needs to be sufficiently small to obtain a speed at which soil can be eroded remotely by the ejection of the liquid emitted from the nozzle. Generally, the inner diameter of the outlet of the nozzle is 2 mm to 5 mm, and the speed of the liquid exiting the nozzle is 100 to several hundred meters per second (m / s).
[0004]
In order to ensure good jetting, it is desirable to optimize the internal shape of the nozzle so that the jetting of the liquid is maintained as high as possible when transporting the liquid from the nozzle toward the soil. To be able to erode as much soil as possible with minimal kinetic energy. Nozzle shapes optimized to meet this need are used in a wide range.
[0005]
However, it has been found that even with such a nozzle, the soil erosion effect of the liquid squirt is quickly lost, in which case the drill string moves in parallel and arbitrarily rotating, for example from the nozzle. Significant levels of kinetic energy are required to erode the soil at distances as far as a few decimeters (dm). Also, the active diameter of the pressurized liquid jet to form a cylinder, fan, or planar element depends on the method to be implemented, the nature of the soil, and the energy provided, and is generally a few decimeters to 1 meter (m) or In the range of 2 m, it remains insufficient.
[0006]
[Problems to be solved by the invention]
For the purpose of enhancing the ejection effect, in particular, in US Pat. No. 5,228,809, a proposal has been made to satisfy the demand for improving the ejection characteristics for an injection head or a monitor.
[0007]
The attached FIG. 1 shows an injection head according to the above-mentioned patent invention. The injection head 10 includes a body 12 having a side wall 14 defining an interior space. A nozzle 16 for injecting pressurized liquid is mounted in the outer wall 14 of the monitor. Also shown is an element 18 connected to the drill string and a drill string connected to a pipe of pressurized liquid and capable of introducing liquid to the injection nozzle and simultaneously supplying air to the annular nozzle. Elements 20, 22 connected to annular air pipes arranged along are shown. According to this patent invention, from the pipe 22 for supplying the pressurized liquid, through the passage 24 formed in the main body of the monitor 10 and the tube 26 connecting the end of this passage and the insertion port of the injection nozzle 16. Thus, the liquid is introduced into the injection nozzle 16. Tube 26 has a constant cross-section and regularly varying curvature to limit the turbulence of the pressurized liquid that occurs between the drill string and injection nozzle 16 itself. However, as described, the diameter of the injection nozzle is very small compared to the diameter of the pipe that supplies the pressurized liquid disposed along the drill string. Therefore, the solution presented in the above-mentioned US patent invention is not completely satisfactory.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an injection head capable of further improving the ejection characteristics from a nozzle of an injection head attached to a lower end of a drill string, particularly an injection head for performing jet grouting. .
[0009]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a head attached to an end of a drill string including a liquid supply means for supplying a pressurized liquid, for injecting a pressurized liquid from a boring hole to disperse soil, A body having an outer wall and an upper end connected to the lower end of the drill string, at least one injection nozzle attached to the body, having an insertion port diameter d and along the axes x, x '; At least one bend including a first end connected to the lower end of the supply means and a second end connected to the nozzle tangentially to the axes x, x 'and having a continuously changing radius of curvature; Supplying the supplied liquid to the nozzle having a defined centerline and having a cross-section that is regularly reduced over at least half of the length from the first end to the second end. To provide a head, characterized in that a duct forming means for introducing into and included mouth.
[0010]
The cross-section of the duct forming means, e.g. a tube, extends over at least half the length from the end connected to the pipe for supplying the pressurized liquid to the connection to the insertion orifice of the injection nozzle, It will be appreciated that the progressive and regular reduction substantially improves the characteristics and direction of ejection from the injection nozzle. Still further, by adding the feature that the center line of the duct forming means has a radius of curvature that changes regularly, it is possible to minimize the disturbance of the liquid flow generated in the tube, A maximum energy eruption with erosive power maintained up to the maximum distance from the soil to the soil is achieved.
[0011]
In a first embodiment, the axis of the liquid supply means is substantially coincident with the axis of the body of the injection head, and the center line of the duct forming means is such that the recess has a first sign and has a regularly varying curvature. A first curved portion from the one end to the middle point, and a second curved portion from the middle point to the second end, wherein the concave portion has a sign opposite to the first sign and has a regularly changing curvature. I have.
[0012]
Due to the special shape of the duct forming means such as a tube having two curved portions as described above, for a given outer diameter of the injection head, the length of the tube is increased and the injection nozzle in the tube is increased. It will be appreciated that it is possible to increase the length of the part exhibiting a large radius of curvature, which is directly connected to
[0013]
In a second embodiment, a feed tube for feeding the liquid is provided over the injection head, and the first end of the duct forming means is substantially tangential to the feed tube. It is a side branch of Irisu.
[0014]
Other features and advantages of the present invention will become more apparent with the various embodiments of the present invention set forth below by way of non-limiting examples. For the following description, reference is made to the accompanying drawings.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The injection head 30 shown in FIG. 2 comprises a cylindrical side wall 34, a lower end 36 including means for securing a mechanical boring tool, such as a thread 38, and an upper end 40. A main body 32 is provided. The upper end 40 is connected to a thread 42 for connection with the lower end of the drill string 44 and to a pipe 48 provided inside the drill string 44 for pressurizing and transporting a liquid, generally composed of a slurry as described above. And an inner sleeve 46. In the embodiment specifically shown here, an annular space 50 between the drill string 44 and the pipe 48 is used to carry pressurized air. However, it goes without saying that this annular space may be omitted in other embodiments.
[0016]
Above the lower end 36 is the sidewall 34 of the injection head with the injection nozzle 50 along the x, x 'axis. In the embodiment shown here, the x, x 'axis of the injection nozzle 50 is substantially orthogonal to the vertical axis z, z', but in other embodiments this axis is, for example, relative to the horizontal axis. It may be in the range of + 15 ° to -15 °. Also, as shown in FIGS. 4 and 5, the injection nozzle may be orthogonal to the outer wall of the monitor (injection nozzle 50 ′ of FIG. 4) or may be substantially in contact with the outer wall of the monitor (FIG. 4). 5 and the x, x 'axis may be in any direction therebetween. Inside the cavity 52 of the injection head body, there is an inlet 46 for the pressurized liquid and an injection nozzle 50. There is a tube 54 connecting the insertion port 50. The cross section of the pipe 46 for introducing the pressurized liquid is written as S1, and the cross section of the insertion port of the injection nozzle 50 is s1. The tube 54 having the centerline L has a first end 56 connected to the pipe 46 and a second end 58 connected to the injection nozzle, the first end 56 of the tube 54 being transverse. It has the same cross section S′1 as the surface S1, and the second end has an injection nozzle. Has the same cross section s'1 as the cross section s1 of the tube 54. Further, the cross section of the tube 54, that is, the cross section of the tube in a plane perpendicular to the center line L is regular from S'1 to s'1. Tube 54 may include a very short cylindrical portion.
[0017]
The cross section of the tube may be circular, but may be oval, elliptical, etc. The cross-sections of the ends 56, 58 are generally circular, but they may also be elliptical. The center line L of the tube 54 has a curvature that is not constant but changes regularly. In the embodiment shown in FIG. 2, the center line L of the tube 54 defines the first curved portion L1 from the first end 56 to the intermediate point A and the second curved portion L2 from the intermediate point A to the second end 58. Have. The radius of curvature of the first curved portion L1 maintains the same sign, and the radius of curvature of the second curved portion L2 also maintains the same sign. However, the sign of the radius of curvature of the second curved portion L2 and the first curved portion L1 Is opposite to the sign of the radius of curvature. That is, the first curved portion L1 and the second curved portion L2 are connected so as to be in contact with each other at an intermediate point A which is an inflection point of the center line L.
[0018]
In the present embodiment, in particular, the second curved portion L2 of the center line, that is, the portion corresponding to the tube makes it possible to increase the length of the portion having a large radius of curvature in the region of the tube connected to the injection nozzle. . Further, with such a configuration, the flow of the pressurized liquid in the tube 54 near the injection nozzle 50 can be further stabilized.
[0019]
Of course, the tube 54 has another curvature provided that its center line has a regularly varying curvature and its cross-section is reduced substantially regularly from a first end 56 to a second end 58 which joins the injection nozzle. It may be shaped. The tube needs to have only one radius of curvature, but its center line is not in one plane and may form a spiral, ie, a three-dimensional curve.
[0020]
Obviously, the injection head having a plurality of nozzles does not depart from the spirit of the invention, in such an injection head having a plurality of tubes similar to the tubes 54, each of which is included in the drill string. And it becomes the structure couple | bonded separately with the pipe which introduces the pressurized liquid.
[0021]
When the tube 54 is shaped as shown in FIG. 2, it is possible to keep the outer dimensions of the working portion of the injection head within small values corresponding to the diameter D1 and the height H1, and to reduce the center line L of the tube. Note that it is possible to increase the overall length. By increasing the length of the tube 54, it becomes possible to more gradually reduce the cross section with respect to the predetermined cross section at the two ends of the tube. In the embodiment shown, the diameter D1 is less than 15 centimeters (cm) and the active height H1 of the injection head is less than 50 cm.
[0022]
FIG. 3 shows a second embodiment of the monitor according to the present invention. In this monitor, a pipe 48 for introducing pressurized liquid is extended into the monitor by a pipe 70 for feeding liquid to a mechanical tool mountable in the threaded sleeve 38. In that they are essentially different. When the mechanical tool is installed, liquid is pumped into the mechanical tool by the pipe 70 via the controllable valve 72. In such a case, the first end 56 ′ of the tube 54 ′ becomes a side branch of the pipe 70. This side branch is preferably substantially tangential to the wall of the pipe 70.
[0023]
In the present embodiment described above, it will be understood that the center line L 'of the tube 54' is a three-dimensional curve. The tube 54 '"wraps" around the pipe 70 from the side branch 56' to the insertion port of the injection nozzle 50.
[0024]
In the above description, the tube 54 is a portion separated from a pipe mounted inside the main body of the injection head. However, even if the main body of the injection head is a molded product, and the tube 54 is formed by an appropriate technique during the molding, it does not depart from the gist of the present invention. In such a case, the main body of the injection head may be a solid product in which the tube 54 is constituted by a cavity formed therein.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a known injection head.
FIG. 2 is a longitudinal sectional view showing a first embodiment of an injection head or a monitor according to the present invention.
FIG. 3 is a longitudinal sectional view showing a second embodiment of the injection head according to the present invention.
FIG. 4 is a partial cross-sectional view showing an example of embedding in an injection nozzle according to the present invention.
FIG. 5 is a partial cross-sectional view showing another example of embedding in the injection nozzle according to the present invention.
[Explanation of symbols]
30 injection head 32 main body z 'injection head main body shaft 34 side wall (outer wall)
36 Lower end 40 Upper end 44 Drill string 48 Pipe (liquid supply means)
z Pipe (liquid supply means) shaft 50, 50 ', 50''Injection nozzle (monitor)
54, 54 'tube (duct forming means)
56, 56 'First end 58 Second end L Center line L1 of tube (duct forming means) First curved portion L2 Second curved portion A Intermediate point 70 Pipe (inlet pipe)

Claims (10)

A head attached to an end of a drill string including a liquid supply means for supplying a pressurized liquid, for injecting a pressurized liquid from a boring hole to disperse soil;
A body having an outer wall and an upper end connected to the lower end of the drill string;
At least one injection nozzle attached to the body, having an insertion port diameter d and having axes x, x ';
At least one having a first end connected to the lower end of the liquid supply means and a second end connected to the injection nozzle tangentially to the axes x and x 'and having a continuously changing radius of curvature. Injecting the supplied liquid having a centerline defined by a bend and having a cross-section that is regularly reduced over at least half of the length from the first end to the second end; A duct forming means for introducing the nozzle into the insertion port of the nozzle. The pressurized liquid injection head according to claim 1, wherein a first end of a center line of the duct forming unit is connected tangentially to an axis of a lower end of the liquid supply unit. The axis of the liquid supply means is substantially coincident with the axis of the body of the injection head, and the center line of the duct forming means is from the first end where the recess has a first sign and has a regularly varying curvature. A first bend to an intermediate point, and a second bend from the intermediate point to the second end, the recess having a sign opposite to the first sign and having a regularly changing curvature. The pressurized liquid injection head according to claim 1, wherein 2. The pressurized liquid injection head according to claim 1, wherein said duct forming means has a substantially circular cross section. The pressurized liquid injection head according to claim 1, wherein the duct forming means has an oval cross section. 2. The pressurized liquid injection head according to claim 1, comprising a plurality of injection nozzles and a plurality of duct forming means connected to the individual injection nozzles. 2. The pressurized liquid injection head according to claim 1, wherein the duct forming means is a tube separated from the main body of the injection head. 2. The pressurized liquid injection head according to claim 1, wherein the main body of the injection head is a molded product, and the duct forming means is formed during the molding. A head attached to an end of a drill string including a liquid supply means for supplying a pressurized liquid, for injecting a pressurized liquid from a boring hole to disperse soil;
A body having an upper end, a lower end, and an outer wall connected to the lower end of the drill string;
At least one injection nozzle attached to the body, having an insertion port diameter d and along the axes x, x ';
A tool attached to the lower end of the body,
A feed pipe connected to the liquid supply means and provided throughout the main body, for feeding liquid to the tool;
A first end connected substantially tangentially to the inlet tube and a second end connected to the injection nozzle, the first end connected to the inlet tube and axes x, x '; A centerline defined by at least one curved portion that includes the second end tangentially connected to and has a continuously varying radius of curvature, and whose cross-section is from the first end to the second end. A duct forming means that is regularly reduced over at least half of the length up to the two ends. The axis of the inlet tube is substantially coincident with the axis of the body of the injection head, and the center line of the duct forming means extends from the first end where the recess has a first sign and has a regularly varying curvature. A first bend to an intermediate point, and a second bend from the intermediate point to the second end, the recess having a sign opposite to the first sign and having a regularly changing curvature. The pressurized liquid injection head according to claim 9, wherein:

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