Discharge method of solidification material

Abstract

To provide a discharge method of a solidification material that can create homogeneous stabilized soil.SOLUTION: In a discharge method of a solidification material, a second piping 52 which is a compressed air supply pipe is joined and connected to a first pipe 51 which is a solidification material pressure transport pipe, and a solidification material M is pressurized by compressed air A supplied via the second piping 52, thus, a discharge pressure P of the solidification material M at a solidification material discharge portion 47 is set to be greater than a discharge resistance R. This makes it possible for the solidification material M to reach a tip of a mixing blade 45 against the discharge resistance R of a stabilized soil, and as a result, to contribute to creation of homogeneous stabilized soil and improve quality of the stabilized soil.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for discharging a slurry-like solidification material in a ground improvement method for producing stabilized soil by stirring and mixing in-situ soil (hereinafter abbreviated as "original soil") and a slurry-like solidification material. [Background technology]

[0002] As a method for discharging a slurry solidification material in a ground improvement method, for example, the method described in Patent Document 1 below is known.

[0003] In brief, this method of discharging the solidification material involves providing a flat, wide-angle diffusion zone at the tip of the solidification material pumping pipe, and providing an acceleration zone upstream of the diffusion zone to increase the flow rate of the solidification material. When the cross-sectional area of ​​the solidification material pumping pipe is S1 and the cross-sectional area of ​​the inlet of the diffusion zone is S2, the relationship between the two is set to be "S1 ≧ S2." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3628658 Summary of the Invention [Problem to be solved by the invention]

[0005] During construction, the discharge resistance at the tip of the diffusion area (solidification material discharge port) varies depending on the fluidity and specific gravity (wet density) of the stabilized soil, the position of the solidification material discharge port (improvement depth), and other factors.

[0006] Therefore, even when the above condition (S1≧S2) is satisfied, as in the conventional solidification material discharge method, there is still room for improvement in that, depending on the properties of the stabilized soil, the solidification material may not reach the tip of the agitator blade at the tip of the diffusion area (solidification material discharge port), resulting in the creation of heterogeneous stabilized soil.

[0007] Therefore, the present invention has been devised in consideration of the technical problems of the conventional solidification material ejection methods, and aims to provide a solidification material ejection method capable of producing homogeneous stabilized soil. [Means for solving the problem]

[0008] In one aspect, the present invention provides a method for discharging a solidification material for use in a trencher-type ground improvement method, in which a trencher is used, which has a plurality of agitation blades at a predetermined pitch attached to an endless chain wound between a drive wheel attached to an upper part of a frame and a driven wheel attached to a lower part of the frame, and the plurality of agitation blades are moved around together with the chain to excavate the ground, and the raw soil and a slurry-like solidification material are mixed and stirred to produce a stabilized soil having fluidity, and the stabilized soil has a fluidity value immediately after mixing that is equal to or greater than a fluidity value at which a test specimen can be produced by a test specimen production method that does not involve compaction. the solidification material is pressurized by compressed air supplied through a compressed air supply pipe which is joined and connected to a solidification material pressure pipe provided along the longitudinal direction of the trencher from the base end side to the tip end side of the trencher, and discharged from a solidification material discharge part provided at the tip end of the trencher; when a cross-sectional area of ​​the solidification material pressure pipe is S1 and a cross-sectional area of ​​a solidification material discharge port of the solidification material discharge part is S2, a relationship of "S1>S2" is satisfied, and when a discharge pressure of the solidification material at the solidification material discharge port is P and a discharge resistance is R, a relationship of "P>R" is satisfied.

[0009] In this way, in the present invention, the solidification material is pressurized by compressed air supplied through a compressed air supply pipe that is joined to the solidification material pressure feed pipe, and the discharge pressure P of the solidification material at the solidification material discharge section is set to be greater than the discharge resistance R. This makes it possible for the solidification material to reach the tip of the mixing blade against the discharge resistance of the stabilized soil, and homogeneous stabilized soil can be produced.

[0010] In addition, as another aspect of the method of discharging the solidification material, when the wet density of the stabilized soil is ρ and the depth from the upper end of the ground improvement body to the solidification material discharging portion is H, the relationship is "R ≒ ρ × H".

[0011] In still another aspect of the method for discharging the solidification material, it is desirable that the connection between the solidification material pressure delivery pipe and the compressed air supply pipe is provided on the base end side of the trencher.

[0012] According to the present invention, since the connection between the solidification material delivery pipe and the compressed air supply pipe is provided at the base end of the trencher, the distance from the connection between the solidification material delivery pipe and the compressed air supply pipe to the solidification material discharge port, i.e., the straight portion along the longitudinal direction of the trencher, can be secured longer than when the connection between the solidification material delivery pipe and the compressed air supply pipe is provided at the tip end of the trencher near the solidification material discharge port. This suppresses the drop in discharge pressure after the solidification material and the compressed air join together, ensuring stable discharge of the solidification material.

[0013] Furthermore, if the connection between the solidification material pressure delivery pipe and the compressed air supply pipe is located outside the trencher, the distance between the connection and the solidification material discharge port will be greater, and there is a risk that, for example, a curved portion will be formed in the solidification material pressure delivery pipe, and the pressure of the solidification material pressurized by the compressed air will be attenuated by the curved portion, etc. In contrast, in the present invention, the connection between the solidification material pressure delivery pipe and the compressed air supply pipe is provided in the trencher where the solidification material discharge port is located, thereby suppressing the attenuation of the pressure of the solidification material pressurized by the compressed air downstream of the connection, and ensuring more stable discharge of the solidification material.

[0014] Also, as yet another aspect of the method for discharging the solidifying material, the solidifying material pressure feed pipe has a bent portion where the solidifying material pressure feed pipe bends in the middle of the solidifying material pressure feed pipe, and the compressed air supply pipe is connected along the delivery direction of the solidifying material on the outer peripheral side of the bent portion and downstream of the bent portion. When the pressure of the solidifying material pressure feed pipe at the confluence of the solidifying material and the compressed air is P1 and the pressure of the compressed air supply pipe is P2, it preferably has a relationship of "P1 < P2".

[0015] According to the present invention, when the solidifying material and the compressed air merge, the solidifying material pressure feed pipe and the compressed air supply pipe are connected along the delivery direction of the solidifying material on the outer peripheral side of the bent portion of the solidifying material pressure feed pipe and downstream of the bent portion. Thereby, at the connection portion between the solidifying material pressure feed pipe and the compressed air supply pipe, interference between the flow of the solidifying material and the flow of the compressed air is suppressed, and the compressed air can be more smoothly merged with the flow of the solidifying material.

[0016] Also, by setting the pressure of the compressed air supply pipe to be greater than the pressure of the solidifying material pressure feed pipe, due to the suction effect based on the negative pressure generated with the pressure difference between the pressure of the solidifying material pressure feed pipe and the pressure of the compressed air supply pipe when the compressed air merges, the load on the pump for pressure-feeding the solidifying material is reduced, and more stable pressure-feeding of the solidifying material becomes possible.

[0017] Also, as yet another aspect of the method for discharging the solidifying material, when the pipe diameter of the solidifying material pressure feed pipe is D1 and the pipe diameter of the compressed air supply pipe is D2, it preferably has a relationship of "D1 ≥ D2".

[0018] According to the present invention, by setting the pipe diameter of the solidification material pressure delivery pipe to be equal to or greater than the pipe diameter of the compressed air supply pipe, the flow rate of the compressed air becomes equal to or greater than the flow rate of the solidification material, and the compressed air can be smoothly merged with the solidification material. In particular, when the flows are merged on the outer periphery side of the bent portion, the flow rate on the outer periphery side is faster than that on the inner periphery side of the bent portion, and the pressure inside the pipe on the outer periphery side is lower than that on the inner periphery side of the bent portion, so by setting the pipe diameters of the solidification material pressure delivery pipe and the compressed air supply pipe to have the above relationship (D1≧D2), the compressed air can be more smoothly merged with the flow of the solidification material.

[0019] Furthermore, as yet another aspect of the solidification material discharging method, when the intersection point between the extension line of the inner circumference of the solidification material pressure delivery pipe downstream of the bend and the outer circumference of the solidification material pressure delivery pipe upstream of the bend is defined as X1, and the intersection point between the extension line of the inner circumference of the solidification material pressure delivery pipe upstream of the bend and the outer circumference of the solidification material pressure delivery pipe downstream of the bend is defined as X2, it is desirable that the compressed air supply pipe be connected to the solidification material pressure delivery pipe within the region between X1 and X2 at the bend.

[0020] According to the present invention, the compressed air supply pipe is connected to the solidification material pressure delivery pipe within the region between X1 and X2 at the bent portion. Therefore, the flow of the solidification material is less likely to be hindered by the compressed air compared to a case where the compressed air supply pipe is connected to the solidification material pressure delivery pipe outside the region between X1 and X2, and the compressed air can be smoothly merged with the flow of the solidification material. As a result, the flow of the solidification material is effectively assisted by the compressed air, and more stable discharge of the solidification material can be ensured.

[0021] As yet another aspect of the solidification material discharge method, when the minor angle between the upstream side of the bent portion of the solidification material pressure delivery pipe and the upstream side of the connection portion of the compressed air supply pipe is θ1 and the minor angle between the upstream side and downstream side of the bent portion of the solidification material pressure delivery pipe is θ2 at the connection portion of the solidification material pressure delivery pipe, it is desirable that the relationship be "θ1 < 90°" and "θ1 + θ2 ≒ 180°".

[0022] According to the present invention, by satisfying the relationship of "θ1<90°" and "θ1+θ2≈180°", the interior angle (minor angle) of the bent portion of the solidification material pressure delivery pipe becomes an obtuse angle, and the extending directions of the solidification material pressure delivery pipe and the compressed air supply pipe match after connection. In this way, the solidification material pressure delivery pipe bends gently, and the flow directions of the solidification material and the compressed air match (become the same direction) after merging, allowing the compressed air to merge more smoothly with the flow of the solidification material.

[0023] In other words, if the inner angle (minor angle) of the bent part of the solidification material pumping pipe is an acute angle, the flow resistance of the solidification material at the bent part increases, and the load on the pump increases. In contrast, in the present invention, the inner angle (minor angle) of the bent part of the solidification material pumping pipe is an obtuse angle, which reduces the flow resistance of the solidification material at the bent part and ultimately reduces the load on the pump.

[0024] In addition, if the extension directions of the solidification material pressure delivery pipe and the compressed air supply pipe do not match after connection, the loss of the flow velocity and pressure of the compressed air after merging increases. In contrast, in the present invention, the extension directions of the solidification material pressure delivery pipe and the compressed air supply pipe match after connection, reducing the loss of the flow velocity and pressure of the compressed air after merging, and making it possible to increase the flow velocity and pressure of the compressed air after the merging, effectively improving the discharge pressure of the solidification material.

[0025] The sum of θ1 and θ2 includes errors in the bending of the solidification material pumping pipe and errors in the connection between the solidification material pumping pipe and the compressed air supply pipe, and should be approximately 180° (specifically, 170° to 190°), with an error of about ±10° being allowed.

[0026] In yet another embodiment of the solidification material ejection method, it is desirable that the fluidity value of the stabilized soil immediately after stirring and mixing is 110 mm or more in terms of table flow value.

[0027] If the table flow value of the treated soil immediately after mixing is less than 110mm, depending on the soil properties of the original soil, the resistance during mixing may increase as the viscosity increases, causing the improved soil to become porous immediately after mixing, resulting in a non-homogeneous improved body. In contrast, by making the table flow value of the treated soil immediately after mixing 110mm or more, as in the present invention, a homogeneous improved body can be formed.

[0028] The table flow value of the stabilized soil mentioned above, 110 mm, is due to the fact that the table flow value at the water content (liquid limit) where the clayey soil changes from a plastic state to a liquid state is approximately 110 mm.

[0029] In addition, the fluidity value of the treated soil immediately after stirring and mixing mentioned above refers to treated soil within 15 to 20 minutes after the solidification material is added to the sample soil (raw soil) and stirring and mixing begins, in which gelation (hardening) of the solidification material has not yet progressed.

[0030] As yet another aspect of the method for discharging the solidification material, it is desirable that the solidification material pressure delivery pipe is branched off at a position above the driven wheel of the trencher, and the solidification material is discharged from both sides of the driven wheel so as to be diffused over a wide angle when viewed from the front of the agitator blade.

[0031] According to the present invention, the solidification material discharge section is configured such that the solidification material is discharged from both sides of the driven wheel by the branched solidification material pressure delivery pipe, and is diffused in a wide angle when viewed from the front of the agitator. Therefore, it is possible to spread the solidification material over almost the entire width of the agitator when the trencher moves. In this way, the solidification material is diffused and spread widely within the agitation range of the trencher, improving the mixing and mixing of the raw soil and the solidification material, and creating a more homogeneous stabilized soil. Effect of the Invention

[0032] According to the present invention, the discharge pressure of the solidification material in the solidification material discharge section is set to be greater than the discharge resistance, so that the solidification material can reach the tip of the mixing blade against the discharge resistance of the stabilized soil. This makes it possible to create homogeneous stabilized soil and improve the quality of the stabilized soil. [Brief description of the drawings]

[0033] [Figure 1] 1 is a schematic diagram showing a configuration of a ground improvement device according to the present invention. [Diagram 2] 2A and 2B are enlarged cross-sectional views of the trencher shown in FIG. 1, in which (a) is a front view of the trencher and (b) is a side view of the trencher. [Diagram 3] 3 is an enlarged view of the junction of the solidification material pressure delivery pipe (first piping) and the compressed air supply pipe (second piping) shown in FIG. 2, in which (a) shows the state where the compressed air supply pipe (second piping) joins the outer periphery of the solidification material pressure delivery pipe (first piping), (b) shows the state where the compressed air supply pipe (second piping) joins the inner periphery of the solidification material pressure delivery pipe (first piping), and (c) shows the state where the bent portion of the solidification material pressure delivery pipe (first piping) is formed into an angular shape. [Figure 4] 3 is an enlarged view of the solidification material discharging part shown in FIG. 2, in which (a) is a front view of the solidification material discharging part, and (b) is a side view of the solidification material discharging part. [Diagram 5] 5(a) is a plan view of the solidification material discharging section shown in FIG. 4 alone, (b) is a cross-sectional view along line AA in FIG. 5(a), and (c) is a cross-sectional view along line BB in FIG. 5(a). [Figure 6] 5 is a plan view of the vicinity of the solidification material discharging portion of the trencher shown in FIG. 4, showing the trajectory of the solidification material discharged from the solidification material discharging portion. FIG. [Figure 7] 7(a) is a plan view of the solidification material discharging section shown in FIG. 4, (b) is a cross-sectional view taken along line CC in FIG. 7(a), and (c) is a cross-sectional view taken along line DD in FIG. 7(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the solidification material ejection method according to the present invention will be described in detail with reference to the drawings. In the following embodiment, an example in which the present invention is applied to a trencher type ground improvement method is shown.

[0035] (Configuration of the ground improvement device) Fig. 1 shows a schematic diagram of the trencher type ground improvement device according to this embodiment. Fig. 2 shows an enlarged cross-sectional view of the trencher 4, where (a) shows a front view of the trencher 4 and (b) shows a side view of the trencher 4. In the explanation of each figure, the upper side in the vertical direction in each figure is referred to as "upper", and the lower side in the vertical direction in each figure is referred to as "lower".

[0036] As shown in Fig. 1, the trencher type ground improvement device according to this embodiment is configured with a backhoe 1, which is a construction machine, as a base machine, and a boom 2 and an arm 3 are rotatably connected to the front of a base 1a, which is rotatably mounted on the top of a track 1b, and a trencher 4, which is a mixing and stirring head, is detachably attached to the tip of the boom 2 and the arm 3. The backhoe 1 penetrates the trencher 4 into the ground to a planned improvement depth H, and by operating the boom 2 and the arm 3 to horizontally advance the trencher 4 back and forth, the soil is excavated and the solidification material is mixed and stirred.

[0037] 2, the trencher 4 is configured by wrapping an endless drive chain 43 around a drive wheel 41 that is rotationally driven by a hydraulic motor 44 provided on the upper part of a frame 40, and a driven wheel 42 provided on the lower end of the frame 40. A plurality of stirring blades 45 are attached to the outer periphery of the drive chain 43 at approximately equal intervals (equal pitch), and a plurality of cutter blades 46 are arranged in parallel on each stirring blade 45 along the width direction.

[0038] In addition, a solidification material discharge section 47 that opens downward is provided at the bottom of the frame 40, and a slurry-like solidification material M is discharged from the solidification material discharge section 47. Here, the solidification material M is pressurized by, for example, a pump GP shown in FIG. 1, and is pressure-fed to the solidification material discharge section 47 through a first pipe 51, which is a solidification material pressure-fed pipe provided so as to penetrate the inside of the trencher 4 along the longitudinal direction (frame 40) of the trencher 4. In addition to the pump GP, the solidification material M is also pressurized by compressed air pressurized by, for example, a compressor CP shown in FIG. 1. Specifically, a second pipe 52, which is a compressed air supply pipe connected to the compressor CP, is connected to join the first pipe 51 at the top of the trencher 4, and the solidification material M led to the solidification material discharge section 47 through the first pipe 51 is further pressurized by the compressed air pressure-fed through the second pipe 52.

[0039] It is preferable that the second pipe 52 be joined to the first pipe 51 at an upper portion of the trencher 4 and outside the trencher 4. That is, by joining the second pipe 52 to the first pipe 51 at an upper portion of the trencher 4, it is possible to ensure a longer straight portion of the first pipe 51 arranged along the longitudinal direction of the trencher 4. Also, by joining the second pipe 52 to the first pipe 51 outside the trencher 4, it is possible to easily perform connection work with the first pipe 51 and maintenance work.

[0040] With the above-described configuration, each mixing blade 45 moves in a circular movement in the vertical direction together with the drive chain 43 as the drive wheel 41, which is driven to rotate by the hydraulic motor 44, rotates, and the solidification material M is discharged from the solidification material discharge section 47, thereby stirring and mixing the excavated raw soil and the solidification material M while excavating the ground.

[0041] (Connection configuration of the first and second pipes) 3 is an enlarged view of the joining portion of the first pipe 51 and the second pipe 52, in which (a) shows a state in which the second pipe 52 joins the outer periphery side of the first pipe 51, (b) shows a state in which the second pipe 52 joins the inner periphery side of the first pipe 51, and (c) shows a state in which the bent portion 510 of the first pipe 51 is formed in an angular shape. In the explanation of each view in FIG. 3, the upstream side of the bent portion 510 of the first pipe 51 is defined as the first pipe upstream portion 511, and the downstream side of the bent portion 510 of the first pipe 51 is defined as the first pipe downstream portion 512.

[0042] As shown in Fig. 3(a), in this embodiment, the second pipe 52 is joined and connected near a bent portion 510 (specifically, in the range of an area Y between X1 and X2 described later) of the first pipe 51 bent in an arc shape outside the upper end side of the trencher 4. As a result, the compressed air A pressurized by the second pipe 52 flows into the inside of the first pipe 51, and the solidification material M flowing through the first pipe 51 is further pressurized by this compressed air A and is pressurized and sent to the solidification material discharge part 47 (see Fig. 2).

[0043] Here, in the bent portion 510 of the first piping 51, when an intersection point between an extension line L1 of the inner circumferential side 512a of the first piping downstream portion 512 and an outer circumferential side 511b of the first piping upstream portion 511 is defined as X1, and an intersection point between an extension line L2 of the inner circumferential side 511a of the first piping upstream portion 511 and an outer circumferential side 512b of the first piping downstream portion 512 is defined as X2, the second piping 52 is connected to the first piping 51 in an area Y between X1 and X2 in the bent portion 510. In this embodiment, in the area Y, the second piping 52 is connected to a position shifted from the center of the first piping downstream portion 512 toward the outer circumferential side 512b, specifically, toward the outermost side 512b.

[0044] 3(a), the pipe diameter D1 of the first pipe 51 is set to be equal to or larger than the pipe diameter D2 of the second pipe 52, and they have a relationship of "D1 ≧ D2". In this embodiment, the pipe diameter D1 of the first pipe 51 is set to be larger than the pipe diameter D2 of the second pipe 52. The relationship between the pipe diameter D1 of the first pipe 51 and the pipe diameter D2 of the second pipe 52 is preferably "D1>D2", and more preferably "D1×0.5≧D2".

[0045] 3(a), the connection between the first pipe 51 and the second pipe 52 is configured to have a relationship of "θ1<90°" and "θ1+θ2≈180°" when the minor angle between the first pipe upstream section 511 and the second pipe 52 is θ1 and the minor angle between the first pipe upstream section 511 and the first pipe downstream section 512 is θ2. Here, the sum of θ1 and θ2 includes an error in bending the first pipe 51 and an error in connecting the first pipe 51 and the second pipe 52, and may be approximately 180° (specifically, 170° to 190°), with an error of about ±10° allowed.

[0046] As another aspect of this embodiment, as shown in Fig. 3(b), the second piping 52 may be connected at a position offset toward the inner periphery 512a side from the center of the first piping downstream section 512 in the region Y between X1 and X2 in the bent section 510. Fig. 3(b) shows an example in which the second piping 52 is connected at a position offset toward the innermost periphery 512a side of the first piping downstream section 512.

[0047] 3(a) and 3(b) show an example in which the bent portion 510 is bent in an arc shape, but as shown in Fig. 3(c), the bent portion 510 may be bent in an angular shape. As shown in Fig. 3(c), the second piping 52 may be connected to a radially intermediate position in the vicinity of the center of the first piping downstream portion 512 within the region Y between X1 and X2 in the bent portion 510.

[0048] (Fluidity of stabilized soil) When preparing stabilized treated soil by stirring and mixing using the trencher 4, the stabilized treated soil must have a fluidity value immediately after stirring and mixing that allows test specimens to be made using a test specimen preparation method that does not require compaction.

[0049] The above-mentioned "specimen preparation method without compaction" refers to the specimen preparation method described in "JGS0821," in which stabilized soil is placed in a mold in about three layers, and air bubbles are removed for each layer to prepare a specimen.

[0050] "JGS0821" describes the following as the operation for removing air bubbles: (1) tapping the mold lightly against a concrete floor, (2) hitting the mold with a mallet, (3) placing the mold on a vibration table, etc. Therefore, in order to fill the mold with treated soil using this method to prepare a specimen, the treated soil needs to have a certain level of fluidity. In other words, treated soil with fluidity is treated soil that has a certain level of fluidity immediately after being excavated and stirred and mixed with a solidification material, and that can be packed into a mold by tapping to the extent that air bubbles are removed when preparing a specimen of the treated soil.

[0051] Specifically, for the treated soil to have the above-mentioned certain fluidity, it is desirable for the table flow value of the treated soil immediately after mixing and stirring to be 110 mm.

[0052] The table flow value of the stabilized soil mentioned above, 110 mm, is due to the fact that the table flow value at the water content (liquid limit) where the clayey soil changes from a plastic state to a liquid state is approximately 110 mm.

[0053] The fluidity value of the treated soil immediately after mixing refers to treated soil within 15 to 20 minutes of adding the solidification material M to the sample soil (raw soil) and starting mixing, and refers to treated soil in which gelation (hardening) of the solidification material M has not yet progressed. Although it depends on the soil properties of the raw soil, if the table flow value is less than 110 [mm], the resistance to mixing increases with an increase in viscosity, and the improved soil immediately after mixing may become porous, resulting in a non-homogeneous improved soil. More preferably, the table flow value of the treated soil is 120 [mm] or more, which allows sufficient mixing and is expected to create a more homogeneous improved soil.

[0054] In this embodiment, the table flow value is used as an example of an index of the fluidity value of the stabilized treated soil, but the index of the fluidity value of the stabilized treated soil is not limited to the table flow test, and can also be determined by a slump test, a vane test, etc.

[0055] (Example of solidification material discharge pressure) An example of specific values ​​of the solidification material M and compressed air A at the junction of the first pipe 51 and the second pipe 52 is shown below.

[0056] (1) About solidification materials The amount of solidification material added is 100 [kg / m 3 ], water-cement ratio 100[%], specific gravity of solidification material 3.06, construction volume per hour 50[m 3 13 illustrates an example of the flow velocity S1 of the solidification material M in the first pipe 51 when the flow rate is set to [ / h] and the pipe diameter of the first pipe 51 is set to 1.5 [inches]. First, 1m of raw soil 3 Calculate the amount of solidification material Mx [L] to be pumped per 1m of original soil 3 The amount of solidification material per unit Mx = amount of solidification material added × (1 / specific gravity of solidification material + water-cement ratio), so Mx = 100 [kg / m 3 ]×(1 / 3.06+100[%]) ≒133 [L] Next, 1m of the above raw soil 3Based on the amount of solidification material pumped per hour Mx, the amount of solidification material pumped per hour Vx [L / h] is calculated. Pumping volume of solidification material per hour Vx = 1m of raw soil 3 This is calculated as the amount of solidification material per unit x the amount of construction per hour, so Vx = 133 [L] x 50 [m 3 / h] ≒6634 [L / h] Based on the amount Vx of the solidification material pumped per unit time, the flow velocity Sx [m / sec] of the solidification material M in the first pipe 51 is calculated. The flow rate of the solidification material S1 = the amount of solidification material pumped per second ÷ the cross-sectional area of ​​the first pipe. S1=6634[L / h]÷(1000×60×60)÷[{(38.1[mm]÷1000) 2 ×3.14}÷4 =1.62[m / sec] In this way, the solidification material M is pumped at a speed of 1.62 [m / sec] in the first piping 51. If the second piping 52, which is a compressed air supply pipe, is not joined to the first piping 51, the internal pressure of the first piping 51 near the solidification material discharge portion 47 may become 0.2 [MPa] or less due to pipe resistance.

[0057] (2) Compressed air The following is an example of the supply of compressed air A by a compressor of 2.8 [m 3 1 shows an example of the flow velocity S2 of the compressed air A in the second pipe 52 when the flow rate is set to [ / min] and the pipe diameter of the second pipe 52 is 1.5 [inches]. Flow velocity of compressed air S2 = supply amount of compressed air ÷ flow cross-sectional area of ​​second pipe, so =2.8[m 3 / min]÷60÷〔{(38.1[mm]÷1000) 2 ×3.14}÷4 =40.95[m / sec] In this way, the compressed air A is supplied at a speed of 40.95 [m / sec] in the second piping 52. At this time, the internal pressure of the second piping 52 is about 0.7 [MPa].

[0058] As described above, since the internal pressure P1 of the first pipe 51 is about 0.1 to 0.2 [MPa] and the internal pressure P2 of the second pipe 52 is about 0.7 [MPa], the relationship of "P1 < P2" holds at the confluence of the first pipe 51 and the second pipe 52.

[0059] Also, in this embodiment, at the downstream portion 512 of the first pipe, the second pipe 52 is connected to the outer peripheral side 511b of the downstream portion 512 of the first pipe along the downstream portion 512 of the first pipe. For this reason, when the compressed air A supplied at a speed of 41.0 [m / sec] merges with the solidifying material M pumped at a speed of 1.62 [m / sec], the pressure of the solidifying material M in the downstream portion 512 of the first pipe after the merger increases, and the pumping speed in the downstream portion 512 of the first pipe is accelerated, and the solidifying material is discharged from the solidifying material discharge portion 47.

[0060] (Relationship between discharge pressure and discharge resistance of solidifying material) The compressed air A that merges with the solidifying material M flowing through the first pipe 51 is compressed air pressurized to about 0.7 [MPa] at 1 to 2.5 [m 3 / min] by a compressor. By merging the compressed air A into the first pipe 51 through which the solidifying material M flows, the pressure P of the solidifying material M from the confluence portion to the solidifying material discharge portion 47 is always maintained at 0.3 [MPa] or more. Therefore, although it also depends on the pipe diameter of the first pipe 51 (usually 1.5 to 2.0 inches), the pumping volume Vx [L / min] of the solidifying material, the pumping distance, etc., the discharge pressure P of the solidifying material M at the solidifying material discharge portion 47 is always maintained at 0.3 [MPa] or more.

[0061] Here, for example, when the wet density ρ of the stabilized soil is 1.6 [t / m 3 and the depth H from the upper end of the ground improvement portion to the solidifying material discharge portion 47 is 13 [m], the discharge resistance R at the solidifying material discharge port 470 of the solidifying material discharge portion can be calculated based on the following calculation formula. Since the discharge resistance R at the solidifying material discharge portion = the wet density ρ of the stabilized soil × the depth H from the upper end of the ground improvement portion to the solidifying material discharge portion, R = 1.6 × 13 = 20.8 [t / m 2 ​ ≒0.21 [MPa] In this manner, at the solidification material discharge port 470 of the solidification material discharge section 47, the discharge pressure P of the solidification material M is 0.3 [MPa] and the discharge resistance R is 0.21 [MPa], so that there is a relationship of "P>R."

[0062] (Configuration of solidification material discharge section) Fig. 4 is an enlarged view of the vicinity of the solidification material discharge part 47, where (a) shows a front view of the solidification material discharge part 47 and (b) shows a side view of the solidification material discharge part 47. Fig. 5 is a view showing the solidification material discharge part 47 alone, where (a) shows a plan view of the solidification material discharge part 47, (b) shows a cross-sectional view cut along line AA in Fig. 5(a), and (c) shows a cross-sectional view cut along line BB in Fig. 5(a). Fig. 6 is a plan view of the vicinity of the solidification material discharge part 47 of the trencher 4, and shows the trajectory of the solidification material M discharged from the solidification material discharge part 47.

[0063] 4, the solidification material discharge portion 47 includes a pair of a first solidification material discharge portion 471 and a second solidification material discharge portion 472 formed in a bifurcated shape at the upper portion of the driven wheel 42 of the trencher 4. The first solidification material discharge portion 471 opens downward on one side in the width direction of the driven wheel 42, and the second solidification material discharge portion 472 opens downward on the other side in the width direction of the driven wheel 42. The first solidification material discharge portion 471 and the second solidification material discharge portion 472 have the same shape.

[0064] As shown in FIG. 5, the solidification material discharge section 47 has a cylindrical discharge base 473 having a generally constant outer diameter, and a discharge tip 474 provided at the tip of the discharge base 473 and having a hexagonal shape in plan view. In this embodiment, the discharge base 473 and the discharge tip 474 are integrally formed. The discharge base 473 has a discharge passage 473a having a generally constant inner diameter R1 inside and a circular cross section. The discharge tip 474 has a conical tapered section 474a connected to the discharge passage 473a on the upstream side and having a gradually decreasing inner diameter R2 toward the tip side, and a notched groove 475 provided on the downstream side of the conical tapered section 474a and cut out in a generally rectangular groove shape along the two-face width corresponding to the width direction of the trencher 4. Further, the taper angle θx of the inner diameter R2 is set to an acute angle, and the diameter is reduced relatively gradually from the discharge passage 473a to the conical taper portion 474a.

[0065] In this way, as shown in Fig. 5(b)(c), the solidification material discharge part 47 has a conical taper part 474a and a notched groove 475 at the discharge tip 474, so that the solidification material M flowing along the inner wall of the conical taper part 474a spreads in the longitudinal direction of the notched groove 475, i.e., in the width direction of the trencher 4, and is discharged in a flat trumpet shape. More specifically, the solidification material M flowing along the inner wall of the conical taper part 474a is restricted in diffusion by colliding with the inner wall of the notched groove 475 in the short direction of the notched groove 475, as shown by the dashed arrow in Fig. 5(b)(c), and diffuses only in the longitudinal direction of the notched groove 475, resulting in the flat trumpet shape. At this time, the diffusion angle θm (see Fig. 4) of the solidification material M is equal to the taper angle θt of the conical taper part 474a.

[0066] Here, the conical taper portion 474a needs to be formed in the cross section shown in Fig. 5(b). In other words, in this embodiment, for the convenience of forming the conical taper portion 474a, a mode in which the conical taper portion 474a is formed on the entire circumference is exemplified, but in the cross section shown in Fig. 5(c), the conical taper portion 474a does not necessarily need to be formed.

[0067] As described above, in this embodiment, the solidification material M is discharged in a diffusive manner from the solidification material discharge section 47, and as the trencher 4 advances horizontally, the solidification material M forms a trajectory that spreads across the entire width of the trencher 4, as shown by hatching in Figure 6.

[0068] Figure 7 shows a modified example of the solidification material discharging section 47, where (a) shows a plan view of the solidification material discharging section 47, (b) shows a cross-sectional view taken along line CC in Figure 7(a), and (c) shows a cross-sectional view taken along line DD in Figure 7(a).

[0069] As another embodiment (modification) of the solidification material discharge part 47, the solidification material discharge part 47 may have a discharge base part 473 and a discharge tip part 474 formed separately as shown in FIG. 7. Specifically, a discharge tip part 474 having a notched groove 475 cut into a substantially rectangular groove shape along the width direction of the trencher 4 is attached to the tip part of the discharge base part 473 having a constant inner diameter R1 inside. Furthermore, the discharge tip part 474 is provided with a pair of blocking members 476 at both ends in the longitudinal direction of the notched groove 475 to block the longitudinal opening of the notched groove 475. As a result, the discharge tip part 474 forms a flat opening OP that is larger than the discharge passage 473a in the width direction of the trencher 4 and smaller than the discharge passage 473a in the direction perpendicular to the width direction of the trencher 4.

[0070] In this way, in the solidification material discharge part 47 of this modification, a flat opening OP is formed at the discharge tip 474, so that the solidification material M flowing through the discharge passage 473a diffuses in the longitudinal direction of the notched groove 475 expanding in the width direction of the trencher 4, and the diffusion is restricted by the blocking member 476, so that the solidification material M diffuses in a flat horn shape in the width direction of the trencher 4 when viewed from the front of the trencher 4 as shown by the dashed arrows in Figures 7(b) and (c). At this time, the diffusion angle θm of the solidification material M (see Figure 4) is equal to the taper angle θt formed by connecting the opening edge of the discharge passage 473a and the inner edge of the tip of each blocking member 476 at the opening OP.

[0071] (Effects of this embodiment) Even when the above condition (S1≧S2) is satisfied, as in the case of conventional solidification material discharge methods, there is still room for improvement in that, depending on the properties of the stabilized soil, the solidification material may not reach the tip of the mixing blade at the tip of the solidification material discharge outlet, resulting in the creation of inhomogeneous stabilized soil.

[0072] Specifically, for example, when the solidification material discharge amount is small (about 60 L / min), the pumping pressure of the pump GP is about 0.7 [MPa]. In this case, if the second pipe 52 is not joined to the first pipe 51, the internal pressure of the solidification material M near the solidification material discharge part 47 may drop to 0.2 [MPa] or less due to the pipe resistance.

[0073] Although it depends on the improvement depth H and the fluidity value of the stabilized soil, in the above case, the relationship between the discharge pressure P of the solidification material M and the discharge resistance R becomes "P≦R". This causes the solidification material discharge port 470 of the solidification material discharge section 47 to be temporarily blocked, resulting in a problem that the solidification material M does not reach the tip of the mixing blade 45 at the solidification material discharge port 470. In other words, if the blockage of the solidification material discharge port 470 continues, the pressure P in the solidification material pressure delivery pipe increases to "P>R", so that although the solidification material M is temporarily discharged from the solidification material discharge port 470, it is not discharged stably, which leads to the creation of inhomogeneous stabilized soil and the quality of the stabilized soil may be deteriorated.

[0074] In contrast, in the method of discharging the solidification material according to this embodiment, the second pipe 52, which is a compressed air supply pipe, is joined to the first pipe 51, which is a solidification material pressure transport pipe, and the solidification material M is pressurized by compressed air A supplied through the second pipe 52, so that the discharge pressure P of the solidification material M at the solidification material discharge section 47 is set to be greater than the discharge resistance R. This makes it possible for the solidification material M to reach the tip of the mixing blade 45 against the discharge resistance R of the stabilized soil, which contributes to the creation of homogeneous stabilized soil and improves the quality of the stabilized soil.

[0075] Here, the wet density ρ of the stabilized soil is 1.6 [t / m 3], if the depth H from the upper end of the ground improvement section to the solidification material discharge section 47 is 13 [m], then as calculated above, the discharge resistance R will be approximately 0.21 [MPa], so in order to ensure the relationship "P>R", it is desirable to set the discharge pressure P of the solidification material M to at least 0.3 [MPa] or more.

[0076] In addition, when calculating the discharge resistance R, the relationship is "R ≒ ρ × H" when the wet density of the stabilized soil is ρ and the depth from the top of the ground improvement body to the solidification material discharge part 47 is H. Here, the discharge resistance R is calculated as "R ≒ ρ × H" instead of "R = ρ × H" because there are actually various factors affecting it other than the wet density ρ and depth H of the stabilized soil.

[0077] In this embodiment, the connection portion between the first pipe 51 and the second pipe 52 is provided on the base end side of the trencher 4, i.e., on the arm 3 side in the longitudinal direction. Therefore, it is possible to ensure a longer distance from the connection portion between the first pipe 51 and the second pipe 52 to the solidification material discharge portion 47, i.e., a longer straight portion along the longitudinal direction of the trencher 4, compared to a case in which the connection portion between the first pipe 51 and the second pipe 52 is disposed on the tip end side of the trencher 4 near the solidification material discharge portion 47. This makes it possible to suppress a decrease in the discharge pressure P of the solidification material M after the compressed air A joins with the solidification material M, and ensure stable discharge of the solidification material M.

[0078] Furthermore, if the connection part between the first pipe 51 and the second pipe 52 is disposed outside the trencher 4, the distance between the connection part and the solidification material discharge part 47 will be greater, and for example, a curved part or the like will be formed in the first pipe 51, which may cause the pressure of the solidification material M pressurized by the compressed air A to attenuate. In contrast, in this embodiment, the connection part between the first pipe 51 and the second pipe 52 is provided in the trencher 4 where the solidification material discharge part 47 is disposed, thereby suppressing attenuation of the pressure of the solidification material M pressurized by the compressed air A downstream of the connection part, and ensuring more stable discharge of the solidification material M.

[0079] In addition, in the present embodiment, when the solidifying material M and the compressed air A merge, the first pipe 51 and the second pipe 52 are connected along the delivery direction of the solidifying material M on the outer peripheral side of the bent portion 510 of the first pipe 51 and on the downstream side of the bent portion 510. Thereby, at the connection portion between the first pipe 51 and the second pipe 52, interference between the flow of the solidifying material M and the flow of the compressed air A is suppressed, and the compressed air A can be more smoothly merged with the flow of the solidifying material M.

[0080] In addition, in the present embodiment, the pressure P2 of the second pipe 52 is configured to be greater than the pressure P1 of the first pipe 51, that is, to have a relationship of "P1 < P2". Therefore, when the compressed air A merges, the load of the pump GP that pumps the solidifying material M is reduced due to the suction effect based on the negative pressure generated by the pressure difference between the pressure P1 of the first pipe 51 and the pressure P2 of the second pipe 52, and more stable pumping of the solidifying material M becomes possible.

[0081] In addition, in the present embodiment, the pipe diameter D1 of the first pipe 51 is set to be equal to or greater than the pipe diameter D2 of the second pipe 52, that is, to have a relationship of "D1 ≧ D2". Therefore, the flow velocity of the compressed air A becomes equal to or greater than the flow velocity of the solidifying material M, and the compressed air A can be smoothly merged with the solidifying material M. In particular, when merging on the outer peripheral side of the bent portion 510, since the flow velocity on the outer peripheral side is faster than that on the inner peripheral side of the bent portion 510, the internal pressure of the pipe on the outer peripheral side becomes lower than that on the inner peripheral side of the bent portion 510. For this reason, by setting the pipe diameter D1 of the first pipe 51 to be equal to or greater than the pipe diameter D2 of the second pipe 52, that is, by having the above "D1 ≧ D2", the compressed air A can be more smoothly merged with the flow of the solidifying material M.

[0082] In this embodiment, when the intersection point between the extension line L1 of the inner circumferential side 512a of the first pipe downstream section 512 and the outer circumferential side 511b of the first pipe upstream section 511 is X1, and the intersection point between the extension line L2 of the inner circumferential side 511a of the first pipe upstream section 511 and the outer circumferential side 512b of the first pipe downstream section 512 is X2, the second pipe 52 is connected to the first pipe 51 side within the region Y between X1 and X2 at the bent section 510. Therefore, compared with the case where the first pipe 51 is connected to the first pipe 51 outside the region Y between X1 and X2, the flow of the solidification material M is less likely to be obstructed by the compressed air A, and it is possible to smoothly merge the compressed air A with the flow of the solidification material M. As a result, the flow of the solidification material M is effectively assisted by the compressed air A, and more stable discharge of the solidification material can be ensured.

[0083] In this embodiment, when the minor angle between the upstream side of the bent portion 510 of the first pipe 51 and the upstream side of the connection portion of the second pipe 52 is θ1 and the minor angle between the upstream side and the downstream side of the bent portion 510 of the first pipe 51 is θ2, the relationship is "θ1<90°" and "θ1+θ2≈180°". Therefore, the interior angle (minor angle) of the bent portion 510 of the first pipe 51 becomes an obtuse angle, and the extending directions of the first pipe 51 and the second pipe 52 after connection are the same. In this way, the first pipe 51 is bent gently, and the flow direction of the solidification material M after merging and the flow direction of the compressed air A are the same (they are in the same direction), so that the compressed air A can be more smoothly merged with the flow of the solidification material M.

[0084] That is, if the interior angle (minor angle) of the bent portion 510 of the first piping 51 is an acute angle, the flow resistance of the solidified material M at the bent portion 510 increases, and the load on the pump GP increases. In contrast, in this embodiment, the interior angle (minor angle) of the bent portion 510 of the first piping 51 is an obtuse angle, so that the flow resistance of the solidified material M at the bent portion 510 is reduced, and the load on the pump GP can be reduced.

[0085] Furthermore, if the extending directions of the first pipe 51 and the second pipe 52 after connection do not match, the loss in flow velocity and pressure of the compressed air A after merging increases. In contrast, in this embodiment, the extending directions of the first pipe 51 and the second pipe 52 after connection match, so that the loss in flow velocity and pressure of the compressed air A after merging is reduced and it is possible to increase the flow velocity and pressure of the compressed air A after the merging. This makes it possible to effectively improve the discharge pressure P of the solidification material M.

[0086] In the above relational equation "θ1 + θ2 ≒ 180°," the sum of θ1 and θ2 includes errors in the bending process of the first pipe 51 and the connection process between the first pipe 51 and the second pipe 52, so it is sufficient for the sum to be approximately 180°, specifically 170° to 190°, with an error of about ±10° being tolerated.

[0087] In this embodiment, the table flow value of the treated soil immediately after mixing is 110 [mm]. If the table flow value of the treated soil immediately after mixing is less than 110 [mm], depending on the soil properties of the original soil, the viscosity may increase and the resistance during mixing may increase, causing the improved soil immediately after mixing to become porous, resulting in a non-homogeneous improved body. In contrast, by setting the table flow value of the treated soil immediately after mixing to 110 [mm] or more, as in this embodiment, a homogeneous improved body can be formed.

[0088] In this embodiment, the solidification material discharge section 47 is configured to discharge the solidification material M from both sides of the driven wheel 42 by the branched first pipe 51, and to diffuse in a wide angle from the solidification material discharge port 470 of each solidification material discharge section 47 when viewed from the front of the mixing blade 45. Therefore, when the trencher 4 moves, the solidification material M can be spread over almost the entire area in the width direction of the mixing blade 45. In this way, the solidification material M is diffused and spread widely in the mixing range of the trencher 4, thereby improving the mixing and mixing property of the original soil and the solidification material M, and more homogeneous stabilized soil can be created.

[0089] The present invention is not limited to the configurations exemplified in the above-described embodiments, and can be freely modified according to the specifications of the target object within the scope of the present invention.

[0090] In particular, the connection position between the first pipe 51 and the second pipe 52 is not limited to the form exemplified in the above embodiment, and can be freely changed depending on the specifications of the trencher type ground improvement device to be applied, regardless of whether it is inside or outside the trencher 4 or before or after the bending portion 510. [Explanation of symbols]

[0091] 1...Backhoe (base machine) 2. Boom 3. Arm 4. Trencher 40…Frame 41...Drive wheel 42...Driven wheel 43…Chain 44...Hydraulic motor 45...Mixing blade 46…Cutter blade 51...First pipe (solidification material pressure pipe) 510...Bending part 511…Upstream of the first pipe 511a…Inner circumference side of the upstream part of the first pipe 511b…Outer periphery of the upstream part of the first pipe 512…Second piping downstream part 512a…inner circumference side of the upstream part of the second pipe 512b…Outer periphery of the upstream part of the second piping 52...Second pipe (compressed air supply pipe) GP…Pump CP…Compressor M…Solidification material A…Compressed air P…Discharge pressure R…Discharge resistance

Claims

1. A method for discharging a solidification material used in a trencher type ground improvement method, which uses a trencher having a plurality of agitation blades at a predetermined pitch on an endless chain wound between a drive wheel provided on the upper part of a frame and a driven wheel provided on the lower part of the frame, and excavates the ground by moving the plurality of agitation blades in a circle together with the chain, and also mixes and stirs the raw soil and a slurry-like solidification material to create a stabilized soil having fluidity, comprises: The stabilized soil has a flowability immediately after mixing that allows the preparation of a test specimen by a test specimen preparation method that does not require compaction, The solidification material is pressurized by compressed air supplied through a compressed air supply pipe connected to a solidification material pressure pipe provided along the longitudinal direction of the trencher from the base end side to the tip end side of the trencher, and is discharged from a solidification material discharge portion provided at the tip end of the trencher, When the cross-sectional area of ​​the solidification material pressure-transport pipe is S1 and the cross-sectional area of ​​the solidification material discharge port of the solidification material discharge part is S2, a relationship of "S1>S2" is satisfied, and When the discharge pressure of the solidification material at the solidification material discharge port is P and the discharge resistance is R, the relationship of "P>R" is satisfied. A method for discharging a solidifying material comprising the steps of:

2. The method for discharging a solidifying material according to claim 1, When the wet density of the stabilized soil is ρ and the depth from the top of the ground improvement body to the solidification material discharge part is H, the relationship of "R ≒ ρ × H" is satisfied. A method for discharging a solidifying material comprising the steps of:

3. The method for discharging a solidifying material according to claim 2, The connection between the solidification material pressure pipe and the compressed air supply pipe is provided on the base end side of the trencher. A method for discharging a solidifying material comprising the steps of:

4. The method for discharging a solidifying material according to claim 3, The solidification material pressure-transporting pipe has a bent portion at an intermediate portion of the solidification material pressure-transporting pipe, at which the solidification material pressure-transporting pipe is bent, The compressed air supply pipe is connected on the outer circumferential side of the bent portion along the delivery direction of the solidification material downstream of the bent portion, When the pressure of the solidification material pressure delivery pipe at the joint of the solidification material and the compressed air is P1 and the pressure of the compressed air supply pipe is P2, the relationship of "P1 < P2" is satisfied. A method for discharging a solidifying material comprising the steps of:

5. The method for discharging a solidifying material according to claim 4, When the pipe diameter of the solidification material pressure transport pipe is D1 and the pipe diameter of the compressed air supply pipe is D2, the relationship of "D1 ≧ D2" is satisfied. A method for discharging a solidifying material comprising the steps of:

6. The method for discharging a solidifying material according to claim 5, In the bent portion, when the intersection point between the extension line of the inner circumference of the solidification material pressure pipe downstream of the bent portion and the outer circumference of the solidification material pressure pipe upstream of the bent portion is defined as X1, and the intersection point between the extension line of the inner circumference of the solidification material pressure pipe upstream of the bent portion and the outer circumference of the solidification material pressure pipe downstream of the bent portion is defined as X2, The compressed air supply pipe is connected to the solidification material pressure pipe within the region between the X1 and the X2 at the bent portion. A method for discharging a solidifying material comprising the steps of:

7. A method for discharging a solidifying material according to any one of claims 4 to 6, comprising the steps of: At the connection portion between the solidification material pressure delivery pipe and the compressed air supply pipe, the minor angle between the upstream side of the bent portion of the solidification material pressure delivery pipe and the upstream side of the connection portion of the compressed air supply pipe is θ1, and the minor angle between the upstream side and downstream side of the bent portion of the solidification material pressure delivery pipe is θ2. The relationship is "θ1 < 90°" and "θ1 + θ2 ≒ 180°". A method for discharging a solidifying material comprising the steps of:

8. The method for discharging a solidifying material according to claim 7, The flow value of the stabilized soil immediately after stirring and mixing is 110 mm or more in table flow value. A method for discharging a solidifying material comprising the steps of:

9. The method for discharging a solidifying material according to claim 8, The solidification material pressure delivery pipe is branched at a position above the driven wheel of the trencher, The mixture is discharged from both sides of the driven wheel so as to be diffused in a wide angle when viewed from the front of the mixing blade. A method for discharging a solidifying material comprising the steps of:

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