JP5498881B2 - Ground improvement method - Google Patents

Description

  The present invention relates to a ground improvement method for performing ground cutting with a super-high pressure jet liquid using a swirling jet.

  Conventionally, as a ground improvement method for cutting the ground with an ultrahigh pressure jet liquid, an ultrahigh pressure jet method is known. This ultra high pressure injection method includes single pipe type super high pressure injection method such as CCP method, double pipe type super high pressure injection method such as jet grouting method (JSG method), column jet grouting method (CJG method) and rosin jet pile. There are triple pipe type ultra-high pressure injection methods such as the construction method (RJP method).

  In this ground improvement method of cutting the ground with this kind of ultra-high pressure jet liquid, the super-high pressure jet liquid (cement) is supplied from the curing material injection nozzle of the monitor mechanism provided at the tip of the injection pipe rod inserted to the target depth in the ground. Super-high pressure hardener such as milk) is sprayed into the ground and pulled up while rotating the spray tube rod to perform ground cutting with ultrahigh-pressure jet liquid and mixing stirring of soil particles and hardener with a swirling jet A pile-like solidified body (improved body) is created. The ground cutting / stirring mechanism by the super-high pressure jet liquid is based on the effective action of dynamic pressure action, impact force, pulsation load, cavitation phenomenon, wedge effect, polishing effect and the like.

  As shown in FIG. 7, the monitor mechanism has two hardener injection nozzles N1 and N2 attached to the tube side portion of the monitor tube in the opposite direction perpendicular to the tube axis so that the ultrahigh pressure liquid is reversed. There is a monitor mechanism 1 having a structure for jetting (see, for example, Patent Document 1). According to this, in a single hardened material injection nozzle, the injection reaction force of the ultrahigh pressure hardened material causes blurring at the tip portion of the injection tube rod, but the high pressure in the opposite direction from the two hardened material injection nozzles N1 and N2 Since the liquid is ejected, each of the curing material ejection nozzles N1 and N2 can cancel out the ejection reaction force of each other, and the jet tube rod can be prevented from shaking.

  The two hardener injection nozzles N1 and N2 normally have the axis X1 of one hardener injection nozzle N1 and the axis X2 of the other hardener injection nozzle N2 in parallel. In FIG. 7, when viewed in a direction parallel to the axis of the injection tube rod, an imaginary line Z (in this example, the imaginary line Z of the monitor mechanism 1 is perpendicular to the axis X1 of one of the hardener injection nozzles N1. The axis X2 of the other curing material injection nozzle N2 is also orthogonal to the imaginary line Z. That is, the direction of the axis X1 (angle formed by the imaginary line Z and the axis X1) of one of the hardener injection nozzles N1 measured from the virtual line Z is θ1, and the axis of the other hardener injection nozzle N2 is measured from the virtual line Z If the direction of X2 (the angle formed by the imaginary line Z and the axis X2) is θ2, θ1 = θ2 = 90 °. (Hereinafter, θ1 and θ2 determined in this way are referred to as “injection direction angles” of the curing material injection nozzles N1 and N2, respectively.)

  On the other hand, the injection tube rod is driven to rotate while spraying the ultra high pressure hardened material in the radial direction of the tube from the curing material spray nozzle of the monitor mechanism, and the surrounding ground is cut and stirred by the high pressure jet of the ultra high pressure hardened material. In addition, there is also known a ground improvement method for pulling up the monitor mechanism while rotating the monitor mechanism intermittently so that the monitor mechanism stops at a predetermined rotation angle for one rotation while the monitor mechanism rotates once (for example, Patent Document 2). .

JP-A-56-142914 (FIG. 5) Japanese Patent Publication No. 6-19135

  However, when the monitor mechanism 1 in which the axes X1 and X2 of the curing material injection nozzles N1 and N2 are opposite to each other and parallel is used in the method described in Patent Document 2, the same depending on the setting of the rotation angle. However, there are cases where the material is cut, and there is a possibility that a large non-uniformity may occur in the finished surface around the solidified body.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to provide a ground improvement method capable of finishing the formation surface around the solidified body more uniformly. is there.

  According to the ground improvement method of the present invention, the injection pipe rod is inserted to a target depth in the ground, and the hardening material is inserted from the ultrahigh pressure hardening material inlet of the swivel attached to the head of the injection pipe rod. The injection tube rod is pivotally driven while spraying the ultra-high pressure hardened material in the radial direction of the tube from the hardening material injection nozzle of the monitor mechanism assembled at the tip of the injection tube rod. When the surrounding ground is cut and agitated with a high-pressure jet of high-pressure hardened material, the monitor mechanism is rotated intermittently so that the monitor mechanism is stopped at every predetermined rotation angle during one rotation of the monitor mechanism. In the ground improvement method for raising the monitor mechanism, the two curing material spray nozzles are provided in opposite directions, and the axis of one curing material spray nozzle and the axis of the other curing material spray nozzle Shifted so as not to be parallel to each other, the offset angle is characterized by being set to half of the angle of one rotation angle of said monitor mechanism.

  According to the present invention, the axis of one curing material injection nozzle and the axis of the other curing material injection nozzle are shifted so as not to be parallel to each other, and this shift angle is set to half the rotation angle of the monitor mechanism once. By setting (in other words, setting the rotation angle of the monitor mechanism once to be twice the deviation angle of both injection nozzles), the other curing is performed between the stop positions of one of the curing material injection nozzles. Since the stop position of the material injection nozzle comes, the formation surface around the solidified body can be finished more uniformly.

It is a longitudinal cross-sectional view of the monitor mechanism of one Example of this invention. It is a cross-sectional view of the monitor mechanism of FIG. It is an external view of the swivel attached to the head of the injection pipe rod used for the ground improvement construction method of the present invention. It is explanatory drawing which shows the construction procedure of the ground improvement construction method of one Example of this invention. It is a schematic cross-sectional view of the monitor mechanism of FIG. It is explanatory drawing of the injection direction angle and deviation angle of the ultrahigh pressure liquid from the hardening material injection nozzle of the monitor mechanism of this invention. (A) represents a state when the monitor mechanism is rotated 180 ° (half rotation), and (b) represents a state when the monitor mechanism is rotated 360 °. It is a cross-sectional view of the hardening material injection nozzle portion of the monitor mechanism of the conventional example. It is a longitudinal cross-sectional view which shows the connection part of the ultrahigh pressure liquid channel | path and the hardening | curing material injection nozzle in the monitor mechanism of a prior art example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, a double-pipe structure monitoring mechanism 1 used in the ground improvement method of the present invention is a solidified pile in the ground by a ground improvement method such as a double-pipe super-high pressure injection method such as a jet grout method. It attaches to the front-end | tip part (lower part) of the injection pipe rod 2 for double pipes used when constructing | assembling a body (an improved body, and the same hereafter). A double pipe swivel 5 shown in FIG. 3 is attached to the head (upper part) of the injection pipe rod 2.

  As shown in FIG. 3, the swivel 5 is opened in a part of the upper peripheral surface thereof, and an ultra-high pressure curing material inlet 6 from an ultra-high pressure pump (not shown), a compressed air inlet 5 a, and an ultra-high pressure curing material. A passage 7 that extends from the inlet 6 to the center and communicates with the lower end surface along the axis, and a compressed air passage 5b that communicates from the compressed air inlet 5a to the lower end surface so as to surround the outer periphery of the passage 7. Yes. A hook portion 8 for suspending the injection tube rod 2 with a crane or the like is integrally provided on the head of the swivel 5.

  1 and 2, a double-pipe monitoring mechanism 1 is a two-injection monitoring mechanism 1 having two curing material injection nozzles N1 and N2, and includes an ultra-high pressure curing material passage 4 and a compressed air passage 21. It is attached to the front end side of the injection tube rod 2 of a double tube having The upper end portion of the ultrahigh pressure hardened material passage 4 of the injection tube rod 2 is the ultrahigh pressure hardened material inlet 6 of the double tube swivel 5 shown in FIG. 3, and the upper end portion of the compressed air passage 21 is the compressed air inlet 5a of the swivel 5. And communicate with each other.

  The double-pipe structure monitoring mechanism 1 includes an ultrahigh-pressure liquid passages 11 and 11 communicating with an ultrahigh-pressure hardener inlet 6 of the swivel 5 and an ultrahigh-pressure hardener passage 4 in the injection tube rod 2, and the swivel 5. A monitor pipe 10 having a double pipe structure having a compressed air passage 23 communicating with the compressed air inlet 5a via a compressed air passage 21 in the injection pipe rod 2, and each super high pressure liquid passage on the side of the monitor pipe 10 The two hardener injection nozzles N1, N2 provided so as to communicate with the lower end portion of 11 and the lower end portion of each compressed air passage 23 and provided so as to surround each of the hardener injection nozzles N1, N2. A compressed air injection nozzle 22 is provided.

  The ultra high pressure liquid passage 11 is configured as follows.

  Normally, as shown in FIG. 8, the curing material injection nozzle 31 for injecting the ultra-high pressure jet liquid of the monitor mechanism 30 into the ground is provided at a right angle from the ultra-high pressure liquid passage 32 (for example, JP-A-6-6 No. 306846).

However, in recent ground improvement, the development of ultra-high pressure pumps has progressed, and the discharge volume and discharge pressure of ultra-high pressure jet liquid has become possible. Increasing the diameter of the formation is recommended. By increasing the discharge volume and discharge pressure, increasing the discharge diameter and discharge pressure, increasing the injection pipe rod as a double pipe and triple pipe, increasing the number of curing material injection nozzles, and increasing the number of ultrahigh pressure pumps, We are trying to realize expansion.
Thus, in order to increase the diameter of the formed diameter, it has been required to supply a large amount of ultrahigh pressure hardened material such as cement milk that is pumped through the inside of the injection tube rod.

  However, when a large amount of such ultra-high-pressure hardened material is fed, the increase in the flow rate is unavoidable due to the limitations and limitations of the injection tube rod diameter and the monitor mechanism diameter. In particular, a turbulent flow is inevitably generated in the right-angle portion of the ultrahigh-pressure liquid passage 32 and the hardening material injection nozzle 31 as shown in FIG. This caused energy loss, and there was a limit to increasing the diameter of the product. In addition, due to the increase in the discharge amount and discharge pressure of the ultra-high pressure hardened material accompanying the increase in the diameter of the formed diameter, the monitor mechanism is severely worn, leading to an increase in the consumption cost.

  In order to solve such a problem, the ultrahigh pressure liquid passages 11 and 11 formed in the monitor mechanism 1 have been devised.

  That is, as shown in FIG. 1, the monitor mechanism 1 includes an inlet 9 for receiving an ultrahigh-pressure curing material from the ultrahigh-pressure curing material passage 4 in the injection tube rod 2 communicating with the lower end of the passage 7 of the swivel 5, ultrahigh-pressure curing. Two curing material spray nozzles N1, N2 for spraying the material in the pipe radial direction in mutually opposite directions, and an ultrahigh pressure liquid passage 11 formed in communication between the inlet 9 and each of the curing material spray nozzles N1, N2 It has a double tube structure. Each ultra-high pressure liquid passage 11 includes an inlet-side passage 12 that is continuously located on the inlet 9 side, an injection nozzle-side passage 13 that is continuously located on each of the curing material injection nozzles N1 and N2, and an inlet-side passage 12. At least one intermediate passage located continuously between the injection nozzle side passages 13, that is, in the illustrated example, two first and second intermediate passages 14 and 15 are provided.

  When the corner portion is present in the ultrahigh pressure liquid passage 11 from the inlet 9 of the monitor mechanism 1 to each of the curing material injection nozzles N1 and N2, the present inventor can bend the ultrahigh pressure curing material at the corner portion. If the bend angle exceeds 50 °, the flow state in the ultrahigh pressure liquid passage 11 becomes turbulent when the discharge amount and discharge pressure of the ultrahigh pressure liquid (curing material) increase in the ultrahigh pressure liquid passage 11. I found out. Therefore, the generation of such turbulent flow can be prevented, the ultrahigh pressure liquid smoothly enters the curing material injection nozzle N, and the jet section of the jetted ultrahigh pressure jet is made circular and the size of the circular section is reduced. Corners existing in the ultrahigh pressure liquid passage 11 from the inlet 9 of the monitor mechanism 1 to the respective curing material injection nozzles N1, N2 so that the flying distance of the ultrahigh pressure jet liquid can be dramatically increased. All the bending angles α1 to α4 are set within 50 °.

  Specifically, the angle α1 at which the axis of the inlet side passage 12 bends with respect to the axis of the injection tube rod 2 when viewed from the upstream side in the flow direction, and the first axis with respect to the axis of the inlet side passage 12 when viewed from the upstream side in the flow direction. The angle α2 at which the axis of the first intermediate passage 14 bends, the angle α3 at which the axis of the second intermediate passage 15 bends with respect to the axis of the first intermediate passage 14 when viewed from the upstream side in the flow direction, and the upstream side in the flow direction The angles α4 at which the axis of the injection nozzle side passage 13 bends with respect to the axis of the second intermediate passage 15 when viewed from above are all set within 50 °.

  As specific numerical values of α1 to α4, for example, all of α1 to α4 may be set to 45 °, α1 to α3 may be set to 50 °, and only α4 may be set to 40 °.

  With such a configuration, generation of turbulent flow can be effectively prevented, and the flight distance of the super-high pressure jet liquid can be greatly increased.

  Further, in the present embodiment, when viewed from the upstream side in the flow direction, the axis of the inlet side passage 12 is bent to the opposite side of the axis of the injection tube rod 2 from the side where each of the hardener injection nozzles N1, N2 is located. Is provided with an inlet-side passage 12 extending from the first intermediate passage 14 downward (substantially directly below), and further via a second intermediate passage 15 shorter than the first intermediate passage 14. Since it is connected to the injection nozzle side passage 13, the injection nozzle side passage 13 can be set long. As a result, the flow can be rectified in the injection nozzle side passage 13, and this aspect also contributes to an increase in the flight distance of the ultra-high pressure jet liquid.

  If the inlet-side passage 12, the first and second intermediate passages 14, 15 or the injection nozzle-side passage 13 are formed in a curved shape, rectification is not performed at the outlet of the curved passage. The first and second intermediate passages 14 and 15 and the injection nozzle side passage 13 are respectively formed in a straight line so that the flow of liquid is adjusted on the outlet side (downstream side) of each passage so that there is no turbulent flow. ing.

  The same applies to the bent portions (corner portions) of the ultrahigh-pressure liquid passage 11. If each bent portion is rounded in an arc shape, turbulent flow is likely to occur here. Therefore, the bent portion of the ultrahigh pressure liquid passage 11 is formed at the corner portion.

  The inner surface of the ultra-high pressure liquid passage 11 and the hardener injection nozzles N1 and N2 are mixed with a cemented carbide 16, for example, tungsten carbide and cobalt, in order to reduce wear due to the hardener and to provide wear resistance. It is made of sintered cemented carbide.

  The two hardener injection nozzles N1 and N2 that inject the ultrahigh-pressure liquid in opposite directions are attached to the tube side portion of the monitor tube 10 in the direction perpendicular to the tube axis.

  In the present embodiment, in the two hardener injection nozzles N1 and N2 that inject the ultrahigh pressure liquid in opposite directions, as shown in FIGS. 2 and 5, the axis a of one hardener injection nozzle N1 and the other cure The axis b of the material injection nozzle N2 is shifted so as not to be parallel to each other. The shift angle S at this time is an angle (1/2) θ that is half of the rotation angle θ of the monitor mechanism 1 (see FIG. 6A, the same applies hereinafter). 2 and 5, an arrow T indicates the rotation direction of the monitor mechanism 1. Therefore, the relationship between the jetting direction angles θ1, θ2 and the deviation angle S is θ1 = θ2 + S. In FIGS. 6A and 6B, the radial solid line indicates the stop position of one of the hardener injection nozzles N1 (its axis a), and the radial broken line indicates the axis of the other hardener injection nozzles N2 (of its axis). This represents the stop position of b).

  The one rotation angle θ of the monitor mechanism 1 is preferably varied depending on the size of the formation diameter D of the solidified body P. For example, when the formation diameter D of the solidified body P shown in FIG. 6 is 5000 mm, the one rotation angle θ is 6.00 °, and when the formation diameter D is 4000 mm, the one rotation angle θ is 8.00. When the forming diameter D is 3000 mm, the one rotation angle θ is 12.00 °. As a result, the deviation angle S is also different. That is, when the creation diameter D is 5000 mm, the deviation angle S is 3.00 °, when the creation diameter D is 4000 mm, the deviation angle S is 4.00 °, and when the creation diameter D is 3000 mm, the deviation angle S. Is 6.00 °. Therefore, it is preferable to prepare a number of monitor mechanisms having different deviation angles S in advance and use them according to the formation diameter D. In general, the larger the formation diameter D, the smaller the deviation angle S (therefore, the one rotation angle θ = 2S is also reduced).

  Next, in the ground improvement method according to the present invention by a double pipe type super high pressure injection method such as a jet grout method using the injection tube rod 2 with the monitor mechanism 1 attached to the tip, the solidified body ( A construction procedure for vertically building the improved body (hereinafter the same) P will be described below with reference to FIGS. FIG. 4A is a drilling process diagram using a leading conduit, FIG. 4B is a process diagram for building an injection tube rod, FIG. 4C is a water injection test process diagram, and FIG. 4D is a process for creating a pile-shaped solidified body. FIG. 4E is a drawing process drawing of the injection tube rod. Hereinafter, it demonstrates in order of a process.

(1) Drilling process by the leading conduit As shown in FIG. 4 (a), the boring machine M is installed on the ground, and the drilling by the leading conduit 17 is performed to the target drilling depth while jetting water or bentonite mud. . That is, water or bentonite mud is supplied to the inlet 18a of the swivel 18 connected to the upper end of the leading conduit 17, and the water or bentonite mud is discharged from the lower leading conduit 17a equipped with the metal crown 19 of the leading conduit 17, The leading conduit 17 is lowered while being swung and drilled with a metal crown 19 to insert the leading conduit 17 to a predetermined depth in the ground.

(2) Injection tube rod installation step Next, as shown in FIG. 4B, the injection tube rod 2 having the swivel 5 of FIG. 3 and the monitor mechanism 1 of FIG. After building up to the depth, the tip conduit 17 is pulled out.

(3) Injection test step with water After the injection tube rod 2 is installed, as shown in FIG. 4C, ultra high pressure water is injected into the ultra high pressure hardened material inlet 6 of the swivel 5 of the injection tube rod 2, An injection test is performed by rotating the injection tube rod 2 while continuously injecting ultrahigh pressure water W from the hardened material injection nozzle N of the monitor mechanism 1 in the tube radial direction. If there is no abnormality in the injection test, the ultra high pressure water is switched to an ultra high pressure hardener such as cement milk, and the process for creating a pile-shaped solidified body is started.

(4) Formation Step As shown in FIG. 4 (d), in the formation step, the injection tube rod 2 is pulled up while rotating together with the monitor mechanism 1, and at the same time, the ultrahigh pressure curing material G is cured with the curing material injection nozzles N1, N2. Are sprayed in opposite directions, and the surrounding ground is cut by the jet flow, and the solid particles P are formed in the cutting region by mixing and stirring the soil particles and the hardener. At that time, while the monitor mechanism 1 makes one rotation, the monitor mechanism 1 is stopped for an appropriate second, for example, 0.5 to 2.0 seconds at every predetermined rotation angle θ. Needless to say, the one rotation angle θ of the monitor mechanism is set to be twice the deviation angle S between the axis a of the one curing material injection nozzle N1 and the axis b of the other curing material injection nozzle. Absent.

  Here, because the corners α1 to α4 of the corner portions existing in the ultrahigh pressure liquid passage 11 from the inlet 9 of the monitor mechanism 1 to the respective curing material injection nozzles N1 and N2 are all set within 50 °, Even when the discharge amount of the ultra-high pressure liquid (curing material) increases in the ultra-high pressure liquid passage 11, the generation of turbulent flow can be prevented, and the ultra-high pressure liquid smoothly enters the curing material injection nozzles N1, N2. Therefore, the jet cross section of the jetted ultra-high pressure jet can be made circular and the size of the circular cross-section can be reduced, and the flying distance of the super-high pressure jet liquid can be greatly increased. The formation diameter can be increased. Further, since each of the inlet side passage 12, the first and second intermediate passages 14, 15 and the injection nozzle side passage 13 is formed in a straight line with respect to the direction of liquid flow, the flow of the liquid is discharged to the outlet of each passage. The flow can be adjusted on the side (downstream side), and the flow can be effectively and surely free of turbulence.

  Further, the axis a of one of the curing material spray nozzles N1 and the axis b of the other curing material spray nozzle N2 are shifted so as not to be parallel to each other, and this shift angle S is half of the one rotation angle θ of the monitor mechanism 1. (In other words, the rotation angle θ of the monitor mechanism 1 is set to an angle 2S that is twice the deviation angle S of the two injection nozzles N1 and N2). ), Since the stop position of the other hardener injection nozzle N2 comes between the stop positions of the one hardener injection nozzle N1, the formation surface around the solidified body P can be finished more uniformly.

(5) Extraction step of injection tube rod After completion of the formation, as shown in FIG. 4 (e), the supply of the ultra-high pressure hardener is stopped and the injection tube rod 2 is extracted to the ground. In addition, after pulling out the injection pipe rod 2, the inside of the injection pipe rod 2 is washed with fresh water and moved to the next formation point. Further, the hole 20 generated above the solidified body P by drawing out the injection tube rod 2 is filled with mud, mortar, or the like.

  In the above-described embodiment, the injection tube rod 2 is composed of a double tube, but instead of this, it may be composed of a single tube that does not include the compressed air passage 21 but has only the ultra-high pressure hardened material passage 4. In this case, the swivel 5 is not provided with the compressed air inlet 5a but is provided with only the ultra-high pressure hardened material inlet 6, and the monitor mechanism 1 is replaced with a compressed air passage instead of the double pipe structure. A single-pipe structure monitoring mechanism 1 having only the super-high pressure liquid passage 11 without using 23 is used. Moreover, although the said Example demonstrated what provided the injection nozzle in two places, what was provided in three or more places can also be implemented.

DESCRIPTION OF SYMBOLS 1 Monitor mechanism 2 Injection pipe rod 4 Super high pressure hardening material channel | path 5 Swivel 6 Ultra high pressure hardening material inlet N1, N2 Hardening material injection nozzle a, b Axis line of hardening material injection nozzle S Deviation angle of axis line of hardening material injection nozzle θ Monitoring mechanism One rotation angle of

Claims (1)

The injection tube rod was inserted to the target depth in the ground, and the hardened material was press-fitted at an ultrahigh pressure from the entrance of the ultra high pressure hardened material of the swivel attached to the head of the injection tube rod, and assembled to the tip of the injection tube rod. While rotating the injection tube rod while spraying the ultra high pressure hardened material in the radial direction of the tube from the hard material injection nozzle of the monitor mechanism, cutting and stirring the surrounding ground with the high pressure jet of the ultra high pressure hardened material At the same time, in the ground improvement method of pulling up the monitor mechanism while intermittently rotating the monitor mechanism at every predetermined rotation angle while the monitor mechanism rotates once,
The two curing material spray nozzles are provided in opposite directions, and the axis of one curing material spray nozzle and the axis of the other curing material spray nozzle are shifted so that they are not parallel to each other. Ground improvement method characterized by being set to an angle half of one rotation angle.

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