JP5755786B1 - Construction method for joints - Google Patents

Abstract

[PROBLEMS] To set a proper amount of water added and an additional amount of a solidified material at the time of blanking without generating a shearing force at the joint at the time of blanking and placing a follow-up improved pile. Provide a method. In a joint joint construction method for constructing a continuous improved pile by moving a deep mixing processor so as to have an overlap portion in a traveling direction, a stirring shaft having a plurality of axes in a direction orthogonal to the traveling direction. Is used to build the preceding improved pile 17a, and before solidification of the immediately preceding advanced pile, the solidified material is diffused by blanking so as to have the overlap portion 18, and the subsequent improved pile 17b is traced to the trace of the blanking. In the case of idle driving, water is discharged to diffuse the overlapping agent in the overlap portion, and the solidified material is additionally installed at the time of construction of the post-improvement pile. [Selection] Figure 1

Description

  The present invention relates to a joint joint construction method for constructing so that a predetermined strength can be obtained at a joint joint between adjacent improved piles in an in-situ ground improvement method using a solidified material such as cement. It is.

  As one of the in-situ ground improvement methods using a cement-based solidified material, a deep mixing method is known. In this deep mixing treatment method, as shown in FIG. 13, a deep mixing treatment machine having an excavating blade 14 at the tip of the stirring shaft 11 is made upright on the ground 19 to be improved, and the stirring shaft 11 is moved by an electric motor 12. While rotating, the ground 19 is excavated with the excavating blade 14, the solidified material 16 is discharged from the tip of the injection pipe 15, and the solidified material 16 is mixed with the ground 19 while stirring the ground 19 with the stirring blade 13, to a predetermined depth. A method for constructing a continuous wall or the like by constructing an improved pile 17 and rotating the stirring shaft 11 in the reverse direction and pulling it out, and then moving the deep mixing processor by the approximate diameter of the improved pile 17 and repeating the above operation. It is.

In this deep mixing treatment method, in order to reliably integrate the preceding improved pile 17a and the succeeding improved pile 17b, as shown in FIG. 13 (d), the overhang before the hydration reaction of the solidified material 16 proceeds. It is required to construct the wall of the improved pile 17 by constructing so that the wrap portion 18 is generated and sequentially connecting them.
In order to construct so that the overlap portion 18 is generated, it is necessary to shorten the standby time (joining interval) from the construction of the preceding improved pile 17a to the construction of the subsequent improved pile 17b as much as possible. Specifically, this joining interval is usually preferably within 24 hours, and is managed within 48 hours at the maximum.

  However, the construction may be interrupted due to stormy weather such as a typhoon, and the construction may not be resumed within a controlled joining interval for joining. In particular, in offshore construction, since it is necessary to evacuate the work boat, the joining interval may exceed 7 days.

When the joining interval is equal to or longer than the management time, solidification of the advanced improvement pile 17a proceeds, so that it becomes impossible to penetrate the deep mixing processor so that the overlap portion 18 is generated. In such a case, as shown in FIG. 13 (b), the leading improved pile 17a and the succeeding improved pile 17b have to be placed so as to make point contact, and the joint joint 20 has point or line contact. Since it is formed in a state, it is difficult to evaluate the integrity as an improved wall, and the improvement rate (improved area) defined in the design book cannot be satisfied.
Then, as shown in FIG.13 (c), there exists the construction method which drives the solidification improvement material 21 by the high-pressure injection construction method etc. in the clearance gap part between the preceding improvement pile 17a and the subsequent improvement pile 17b, and improves an integrity. . However, such measures use a machine other than the deep-mixing processor and increase the work of solidification improvement, resulting in a significant increase in construction cost and a delay in the process.

  When it is predicted that the joining interval will be longer than the management time, there is a method of using a slow-hardening cement or retarding material as the solidifying material 16 used for the improved pile 17 immediately before standby to suppress the progress of solidification and lengthening the joining interval. is there. This method has less impact on the cost and work process than the method shown in FIG. 13 (c), but in addition to the slow-hardening cement and retarding material, a device for adding these must be prepared in advance. Don't be. Moreover, the delay effect obtained is limited to about 3 to 5 days.

In addition to these methods, methods have been proposed in which the joints 20 are joined by idle driving of a deep mixing processor (Patent Documents 1, 2, and 3).
In the method described in Patent Document 1, as shown in FIG. 10 (a), the first pile A causes the ground improvement material to be ejected or discharged within the rotation range of the stirring blade, and the rotation shaft is rotated. It is created by lowering and raising it. Next, the second and third piles B and C are formed by partially overlapping one after another. When the next pile D cannot be created immediately after the pile C is created, as shown in FIG. 10 (b), the pile is lowered while rotating the rotating shaft without supplying the ground improvement material at the position where the pile D is created. Then, the mixture is raised and stirred by a stirring blade. When the blank portion b is formed in this manner, the ground improvement material in the overlap portion a of the pile C is diffused to the blank portion b that is the rotation range of the rotary blade, and the concentration becomes low. As shown in FIG. 10 (c), a pile D is formed in the blanking portion b later.

  In the method described in Patent Document 2, when the improved pile 17 is formed by arranging the biaxial deep mixing processors 10 in the traveling direction as shown in FIG. 11A, in the first step, the inner side in the traveling direction is used. The improved pile 17 is formed only on the rotating shaft, and the blanking b of only the stirring portion is formed on the outer rotating shaft without discharging the solidified material 16. Next, in the second step by moving the deep mixing processing machine, the improved pile 17 is formed at the position of the blanking b of only the previous stirring unit on the inner rotating shaft, and only the stirring unit is empty on the outer rotating shaft. Strike b is formed. Thereafter, the deep-mixing processor 10 is sequentially moved to form a continuous wall. FIG.11 (b) shows the example which uses the 3 axis | shaft deep mixing processing machine 10, forms the improvement pile 17 in the inner 2 axis | shaft, and forms the blanking part b only of a stirring part in the outer 1 axis | shaft. FIG. 11 (c) shows an example in which an improved pile 17 is formed on the inner three shafts, and an empty portion b of the stirring portion is formed on the outer one shaft, using the four-axis deep mixing processor 10. FIG. 11 (d) shows an example in which a deep pile processing machine 10 with four axes is used, an improved pile 17 is formed on the inner two axes, and an empty portion b having only a stirring portion is formed on the outer two axes. Is shown.

  In the lower left column of the second page of Patent Document 3, in the case of forming a blanking portion as shown in FIG. 10 or FIG. 11, during excavation, water or poor solidified material 16 (low specific gravity) is injected, It is described that replacement with the solidified material 16 having a high specific gravity injected at the time of another excavation is performed.

Japanese Patent Publication No. 3-59210 JP-A-6-173252 JP-A-4-143310

In the methods shown in Patent Documents 1 and 2, the solidified material 16 of the overlap portion 18 is diffused by idle driving, and the concentration is reduced and solidified, so that the succeeding improved pile 17b can be driven.
However, in these conventional methods, the advancing direction of excavation is a single line in series, so that the solidified material 16 is often insufficiently diffused by idle driving, and the solidified material 16 with the overlapped portion 18 remaining is not suitable. When solidified and the subsequent improved pile 17b is laid, the center of the deep mixing machine 10 is jumped from O1 to O2 by the remaining solidified portion as shown in FIG. In some cases, the core of the improved pile 17b may be hindered from being displaced with respect to the preceding improved pile 17a.
Further, since the traveling direction of excavation is one line in series, as shown in FIG. 12A, when a horizontal external force acts on the adjacent preceding improved pile 17a and the succeeding improved pile 17b, the joint 20 There is a problem that a shear (displacement or rotation) force is likely to occur at the boundary, which may cause a weak point in the structure.
Furthermore, Patent Document 3 describes that water is added at the time of emptying, but the amount of this water added depends on the soil, but if it is too small, solidification proceeds and the effect of emptying cannot be obtained. If the amount is too large, the strength expression rate drops rapidly, and an appropriate amount of water has been desired.

The present invention does not cause troubles such as misalignment of the core with the preceding improved pile 17a when the idle improved pile 17b is driven by forming the blanking portion, and shearing is performed at the joint 20 as a boundary. The object is to provide a method for constructing joints that do not generate any (displacement or rotation) force.
Furthermore, an object of the present invention is to provide a method for setting an appropriate amount of water at the time of emptying and a method for setting an appropriate extra amount of a solidified material.

In the joint joint construction method according to the present invention, the ground 19 is excavated by the excavating blade 14 while rotating the agitation shaft 11 of the deep mixing processor 10, the solidified material 16 is discharged from the tip of the injection pipe 15, and the agitating blade 13. After stirring and mixing, the improved pile 17 is formed, the stirring shaft 11 is pulled out, the deep mixing machine is moved so as to have the overlap portion 18 in the traveling direction, and the above operation is repeated to construct a continuous wall and the like. In the construction method of joint joints to
The step of constructing the preceding improved pile 17a using the stirring shaft 11 having a plurality of axes in the direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile 17a, a step of forming the blank portion 17c so as to have the overlap portion 18 and diffusing the solidified material 16,
And a step of constructing the succeeding improved pile 17b on the trace of the empty portion 17c.

During the step of forming the blank portion 17c, water is discharged instead of the solidified material 16, and the overlap portion 18 of the preceding improved pile 17a is diffused.
The amount of water discharged is at least the amount of the solidified material 16 at the time of construction of the advance improvement pile 17a.
In addition, in the case of clay soil, the amount of water discharged is limited to 15% with respect to 1 m ^{3 of} the solidified soil, and the strength expression rate is within a range not lower than 90% when water is not discharged.

  The process of constructing the succeeding improved pile 17b on the trace of the blanking portion 17c is a subsequent improvement in which the solidifying material 16 is added more than the preceding improved pile 17a and constructed on the trace of the preceding preceding improved pile 17a and the blanking section 17c. The strength of the joint 20 at the boundary of the overlap portion 18 with the pile 17b is increased.

The surplus of the solidifying material 16 is 1.2 times the upper limit when the preceding improved pile 17a is constructed.
In the case of cohesive soil, the amount of water discharged in place of the solidifying material 16 during the step of forming the empty portion 17c is limited to 15% with respect to 1 m ^{3 of} the solidified soil, and the strength expression rate is not when water is not discharged. The amount that does not fall below 90% and the amount of the solidified material 16 added during the process of constructing the succeeding improved pile 17b on the trace of the blank portion 17c is 1.2 times the upper limit of the preceding improved pile 17a. As described above, the strength of the joint 20 at the boundary of the overlap portion 18 between the immediately preceding improved pile 17a and the subsequent improved pile 17b built on the trace of the blank portion 17c is increased.

According to the first aspect of the present invention, the ground is excavated with the excavating blade while rotating the stirring shaft of the deep mixing processor, the solidified material is discharged from the tip of the injection pipe, and the agitating blade is stirred and mixed. In the construction method of the joint joint which constructs and pulls out the stirring shaft, moves the deep mixing treatment machine so as to have an overlap part in the traveling direction and repeats the above operation to construct a continuous wall, etc.
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
Because it consists of the process of constructing a follow-up improved pile on the trace of the empty part,
When forming a follow-up improved pile by forming an empty portion, there is no hindrance such as misalignment with the preceding improved pile, and there is a shear (displacement and rotation) force at the joint joint. Without generating, it is possible to increase the strength of the joint.
In addition, since the solidified material of the overlapped portion of the immediately preceding improved pile was diffused by discharging water instead of the solidified material during the process of forming the blanking portion, the progress of solidification of the overlapped portion was ensured Can be suppressed.
In addition, since the amount of water discharged is the amount of solidified material at the time of construction of the advanced improvement pile at the minimum, the solidification material of the overlapped portion of the previous advancement improvement pile is pushed out and replaced with water, suppressing the progress of solidification be able to.

According to the invention of claim 2 , the ground is excavated with the excavating blade while rotating the agitation shaft of the deep mixing treatment machine, the solidified material is discharged from the tip of the injection pipe, and the agitation blade is agitated and mixed. In the construction method of the joint joint which constructs and pulls out the stirring shaft, moves the deep mixing treatment machine so as to have an overlap part in the traveling direction and repeats the above operation to construct a continuous wall, etc.
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
Because it consists of the process of constructing a follow-up improved pile on the trace of the empty part,
When forming a follow-up improved pile by forming an empty portion, there is no hindrance such as misalignment with the preceding improved pile, and there is a shear (displacement and rotation) force at the joint joint. Without generating, it is possible to increase the strength of the joint.
In addition, since the solidified material of the overlapped portion of the immediately preceding improved pile was diffused by discharging water instead of the solidified material during the process of forming the blanking portion, the progress of solidification of the overlapped portion was ensured Can be suppressed.
Discharge rate of the water in the case of cohesive soil soil, the limit of 15% based solidification soil 1 m ^3, the strength expression rate was in the range of not less than 90% when no discharge of water, the Tokyo Bay Clay The best joint joint construction method can be implemented.

According to the invention of claim 3 , the ground is excavated with the excavating blade while rotating the stirring shaft of the deep mixing processor, the solidified material is discharged from the tip of the injection pipe, and the agitating blade is stirred and mixed. In the construction method of the joint joint which constructs and pulls out the stirring shaft, moves the deep mixing treatment machine so as to have an overlap part in the traveling direction and repeats the above operation to construct a continuous wall, etc.
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
It consists of the process of constructing a follow-up improved pile on the trace of the empty part,
Instead of solidifying material in the process of forming the idle portion, water is discharged to diffuse the overlap portion of the immediately preceding improved pile,
The amount of water discharged is at least the amount of solidified material at the time of construction of the advanced improvement pile. In the case of clay soil, the amount of water discharged is limited to 15% with respect to 1 m ^{3 of} solidified soil , and the strength expression rate is Since the range is set so as not to fall below 90% when water is not discharged, in addition to the effect of the invention according to claim 1, the best construction method for joint seams can be implemented on the ground of Tokyo Bay clay.

According to invention of Claim 4 , excavating the ground with a drilling blade while rotating the stirring shaft of the deep mixing processor, discharging the solidified material from the tip of the injection pipe, stirring and mixing with the stirring blade, In the construction method of the joint joint which constructs and pulls out the stirring shaft, moves the deep mixing treatment machine so as to have an overlap part in the traveling direction and repeats the above operation to construct a continuous wall, etc.
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
Because it consists of the process of constructing a follow-up improved pile on the trace of the empty part,
When forming a follow-up improved pile by forming an empty portion, there is no hindrance such as misalignment with the preceding improved pile, and there is a shear (displacement and rotation) force at the joint joint. Without generating, it is possible to increase the strength of the joint.
In addition, since the process of constructing the succeeding improved pile on the trace of the blanking portion has increased the solidification material than the preceding improved pile, the succeeding improved pile constructed on the trace of the preceding preceding improved pile and the blanking portion and It is possible to increase the strength of the joint at the boundary in the overlap portion.

According to the invention described in claim 5 , in addition to the effect of the invention described in claim 4, the increase of the solidified material is limited to 1.2 times that at the time of construction of the preceding improved pile, so a joint joint is provided. Even in this case, it is possible to obtain a compressive strength without joints.

According to the invention described in claim 6 , the ground is excavated with the excavating blade while rotating the stirring shaft of the deep mixing processor, the solidified material is discharged from the tip of the injection pipe, and the agitating blade is stirred and mixed. In the construction method of the joint joint which constructs and pulls out the stirring shaft, moves the deep mixing treatment machine so as to have an overlap part in the traveling direction and repeats the above operation to construct a continuous wall, etc.
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
Because it consists of the process of constructing a follow-up improved pile on the trace of the empty part,
When forming a follow-up improved pile by forming an empty portion, there is no hindrance such as misalignment with the preceding improved pile, and there is a shear (displacement and rotation) force at the joint joint. Without generating, it is possible to increase the strength of the joint.
In addition, in the case of cohesive soil, the amount of water discharged in place of the solidified material during the step of forming the idle portion is limited to 15% with respect to 1 m ^{3 of} the solidified soil , and the strength expression rate does not discharge water. The amount of additional solidification material during the process of constructing a follow-up improved pile at the site of an unsettled portion is the upper limit of 1.2 times that of the preceding improved pile. The strength of the joint seam at the boundary of the overlap between the preceding improved pile and the succeeding improved pile built on the trace of the empty cast is increased. The solidified material in the overlap portion is extruded and replaced with water, and the progress of solidification can be suppressed. Moreover, even when a joint is provided, it is possible to obtain a compressive strength without a joint.

It is process drawing which shows Example 1 of the construction method of the joint joint by this invention. It is explanatory drawing of the deep mixing process method by a general 4-axis deep mixing processor. It is a figure showing the physical property of marine clay collected in Tokyo Bay. It is a figure showing the result of a compounding test (1). It is a graph of a hydrolysis rate and an intensity expression rate. It is a figure showing the result of a compounding test (2). It is a graph which shows the relationship between the average value of compressive strength, and cement addition amount. It is a figure showing the compression test result of the test body which has a joint joint. The other Example of this invention is shown, (a) is explanatory drawing of Example 2, (b) is explanatory drawing of Example 3, (c) is explanatory drawing of Example 3. FIG. It is explanatory drawing of the conventional deep-layer mixing processing method represented by patent document 1. FIG. It is explanatory drawing of the conventional deep-layer mixing processing method represented by patent document 2. FIG. It is explanatory drawing of the problem of the conventional construction method. It is explanatory drawing of the conventional deep-layer mixing processing method.

According to the construction method of the joint according to the present invention, the ground 19 is excavated by the excavating blade 14 while rotating the stirring shaft 11 of the deep mixing processor, the solidified material 16 is discharged from the tip of the injection pipe 15, and the stirring blade 13 is used. After stirring and mixing, the improved pile 17 is formed, and the stirring shaft 11 is pulled out, and then the deep mixing processing machine is moved so as to have the overlap portion 18 in the traveling direction, and the above operation is repeated to construct a continuous wall and the like. In the construction method of joint joints,
The step of constructing the preceding improved pile 17a using the stirring shaft 11 having a plurality of axes in the direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile 17a, a step of forming the blank portion 17c so as to have the overlap portion 18 and diffusing the solidified material 16,
And a step of constructing a follow-up improved pile 17b on the trace of the blank portion 17c.

Water is discharged instead of the solidified material 16 during the step of forming the blank portion 17c, and the overlap portion 18 of the immediately preceding advanced pile 17a is diffused.
The amount of water discharged is at least the amount of the solidified material 16 at the time of construction of the advance improvement pile 17a.
In the case of clay soil, the amount of water discharged is limited to 15% with respect to 1 m ^{3 of} the solidified soil, and the strength expression rate is within a range not lower than 90% when water is not discharged.

The process of constructing the succeeding improved pile 17b on the trace of the blanking portion 17c is the subsequent improving pile constructed by adding the solidifying material 16 to the previous improved pile 17a and building the trace of the preceding precedent improved pile 17a and the blanking section 17c. The strength of the joint 20 at the boundary in the overlap portion 18 with 17b is increased.
The surplus of the solidifying material 16 is 1.2 times the upper limit when the preceding improved pile 17a is constructed.

In the case of cohesive soil, the amount of water discharged in place of the solidifying material 16 during the step of forming the empty portion 17c is limited to 15% with respect to 1 m ^{3 of} the solidified soil, and the strength expression rate is not when water is not discharged. The amount that does not fall below 90% and the amount of the solidified material 16 added during the process of constructing the succeeding improved pile 17b on the trace of the blanked portion 17c is immediately before the upper limit of 20% when the preceding improved pile 17a is constructed. The strength of the joint 20 at the boundary at the overlap portion 18 between the preceding improved pile 17a and the trailing improved pile 17b constructed on the trace of the blanking portion 17c is increased.

In Example 1 according to the present invention, a four-axis deep mixing processor having two axes in the vertical direction (direction orthogonal to the traveling direction) and two axes in the lateral direction (the same direction as the traveling direction) as shown in FIG. 2 is used. A method for constructing the joint according to the present invention will be described.
In FIG.
(A): A deep-mixing processing machine having an excavating blade 14 at the tip of the stirring shaft 11 is placed upright on the ground 19 to be improved.
(B): The ground 19 is excavated by the excavating blade 14 while the stirring shaft 11 is rotated by the electric motor 12, the solidified material 16 is discharged from the tip of the injection pipe 15, and the solidified material is stirred while the ground 19 is stirred by the stirring blade 13. 16 is mixed with the ground 19.
(C): The improved pile 17 is created to a predetermined depth.
(D): The stirring shaft 11 is reversely rotated and pulled out.
(E): After pulling out, the deep layer processing machine is moved in anticipation of the overlap portion 18 and the above operation is repeated to construct a continuous wall or the like.

As described above, in this deep mixed processing method, the overlap portion 18 is generated before the hydration reaction of the solidified material 16 proceeds in order to reliably integrate the preceding improved pile 17a and the subsequent improved pile 17b. Therefore, it is required to construct the wall of the improved pile 17 by sequentially connecting and constructing.
In order to construct so that the overlap portion 18 is generated, it is necessary to shorten the standby time (joining interval) from the construction of the preceding improved pile 17a to the construction of the subsequent improved pile 17b as much as possible. Specifically, this joining interval is usually preferably within 24 hours, and is managed within 48 hours at the maximum.

The joint joint construction method of the present invention in the case where the standby time (joining interval) may exceed the management time will be described with reference to FIG.
In FIG. 1 (I), it is assumed that the advanced improvement pile 17a is driven and formed by the four-axis deep mixing processor 10, and then the subsequent improvement pile that continues to the advance improvement pile 17a due to the approach of a typhoon or the like. It is assumed that the management time may be exceeded until the construction of 17b. In such a case, positioning is performed for forming the blank portion 17c as indicated by the dotted line at the succeeding subsequent position. At this time, since the improved pile 17 is constructed as a series of four cylinders, the overlapped portion 18 is formed so that no cavity is formed between the preceding and subsequent improved piles 17.

In (II), the stirrer 11 is rotated without pouring the solidified material 16 into the position positioned in the previous step, and the ground is diffused (empty) together with the preceding overlap portion 18 to idle the portion 17c. Then, the solidifying material 16 is diluted to prevent the overlapping portion 18 from being solidified. Water is discharged instead of the solidified material 16 at the time of this idle driving. The injection tube 15 that discharges water includes only the injection tube 15b1 and the injection tube 15b2 for diffusing the overlap portion 18, and the injection tube 15b3 and the injection tube 15b4 that do not include the overlap portion 18 do not discharge water. . The water is discharged only when the deep-mixing machine is penetrated, and is not necessary at the time of drawing. The discharge of water is intended to extrude the previously placed cement slurry and replace it with water. Therefore, the discharge amount of water is the same as that of the cement slurry, and the minimum discharge amount. However, in the case of the soil 19 of the clay soil, the discharged water is only mixed with the clay soil and is not drained or replaced. It is expected to dilute the cement slurry by stirring and mixing the discharged water. At this time, if the amount of discharged water is excessively increased, the viscous soil is disturbed more than necessary, and the necessary solidification strength cannot be obtained when the subsequent improved pile 17b is constructed. Therefore, in the case of cohesive soil, the amount of discharged water is limited to 15% in volume ratio with respect to 1 m ^{3 of} treated soil. Details will be described later.

(III) When the blanking portion 17c is formed, the preceding improved pile 17a in which the overlap portion 18 is cut out in an arc shape is obtained.

(IV) Construction of the follow-up improved pile 17b at the spot of the blanking portion 17c is performed in the same manner as the preceding improved pile 17a. At this time, the addition amount of the solidifying material 16 is increased in a range in which the mass ratio is 1.2 times the upper limit. When the placement of the subsequent improved pile 17b is completed, joints 20 having arc-shaped concave portions at two locations are formed. The joint 20 has two arc-shaped concave portions at positions orthogonal to the traveling direction. However, since the rotation directions of the adjacent stirring shafts 11 are opposite to each other, Problems due to the generation of shearing force and rotational axis deviation as shown in 12 (a) and (b) do not occur. The basis for the increase in the solidifying material 16 will be described later.

In FIG. 1 (II), the reason why the amount of discharged water in the case of cohesive soil is limited to 15% by volume with respect to 1 m ^{3 of} treated soil is as follows.
The physical properties of marine clay (Tokyo Bay clay) collected in Tokyo Bay are as shown in FIG.
In the blending test (1), the water content of the Tokyo Bay clay in FIG. 1 was adjusted to w = 18.6% (= liquid limit), and the cement was powdered with respect to the base material amount of 1 m ³ as the base material. A solidified soil specimen having a diameter of 5 cm and a height of 10 cm was prepared by adding 150 kg / m ³ . This is referred to as Case 1, and 5% water is added to Case 1 in an external volume ratio. Case 2 is the same, and 10%, 15%, 20 %, 30% water was added to cases 3, 4, 5, and 6, respectively. The solidified soil specimens prepared in each case were subjected to a compression test on the 28th day of the material age to determine the compression strength. FIG. 4 shows the test results.
In FIG. 4, the strength expression rate is a value obtained by dividing the uniaxial compressive strength value of each case by the compressive strength value of Case 1 as a percentage.

FIG. 5 is a graph showing the relationship between the water addition rate and the strength expression rate shown in FIG.
From FIG. 5, the water development rate is 15% and the strength expression rate is 90%, and when the water addition rate is increased, the strength development rate tends to decrease sharply. The value was 15%. On the contrary, although depending on the base material, it is desirable to set the upper limit of the water addition rate within a range where the strength expression rate does not become 90% or less.

In FIG. 1 (IV), the reason why the addition amount of the solidifying material 16 is increased within a range where the mass ratio is 1.2 times the upper limit is as follows.
The physical properties of marine clay (Tokyo Bay clay) collected in Tokyo Bay are as shown in FIG.
In the blending test (2), the water content of the Tokyo Bay clay shown in FIG. 1 was adjusted to w = 18.6% (= liquid limit), and the amount of cement added was 120 to 1 m ^{3 of the} base material. , 150, 180, 210, 240 kg / m ³ , 5 cm in diameter and 10 cm in height solidified soil specimens were prepared, and a uniaxial compression test was conducted on the 28th day of the material age. Sought a relationship. FIG. 6 shows the test results.

FIG. 7 shows the relationship between the average value of compressive strength shown in FIG. 6 and the amount of cement added. From FIG. 7, the relationship between the cement addition amount x and the compressive strength y is
y = 23.689x-2141.6 (1)
It can be asked. It can be seen from FIG. 7 that the relationship between the cement addition amount x and the compressive strength y is substantially directly proportional.

A blending test (3) was conducted. In this blending test (3), the case of 180 kg / m ³ in the blending test (2) was simulated with the joint joint construction method of the present invention, and the joint joint 20 was artificially provided with a diameter of 5 cm and a height. A 10 cm solidified soil specimen was prepared. At this time, five cases were created with the standby time (joining interval) set to five levels of 0, 3, 5, 7, and 28. FIG. 8 shows the results of investigating the relationship between the waiting time (joining interval) and the compression test for the material age 28 days and 91 days by the compression strength test using this specimen.

In FIG. 8, the strength ratio is a value obtained by dividing the average compressive strength of each case by the average compressive strength of case 1 (without joint 20). That is, the strength expression rate with or without the joint 20 is shown. From this result, it became clear that the compressive strength decreases between 0.72 and 1.00 times when the joint 20 is present. Therefore, when the joint 20 is provided, it is necessary to increase the amount of cement added with the aim of compressive strength in anticipation of reducing the compressive strength. A value obtained by dividing the compressive strength of case 1 by the strength ratio is defined as a target strength.
Next, the amount of cement added corresponding to the target strength is obtained using the above formula (1). A value obtained by dividing the cement addition amount by the cement addition amount of 180 kg / m ³ in case 1 is the cement extra rate. As shown in FIG. 8, the cement premium rate was 1.00 to 1.17. Therefore, when providing the joint 20 for the joint, it is desirable that the cement addition amount is 1.2 times (≈1.17) in consideration of safety in accordance with the case where the compressive strength is most reduced. .

In the first embodiment, a book using a four-axis deep mixing processor having two axes in the longitudinal direction (direction orthogonal to the traveling direction) and two axes in the lateral direction (the same direction as the traveling direction) as shown in FIG. The construction method of the joint joint of the invention has been described.
However, the present invention is not limited to this, and the present invention is to prevent the occurrence of problems due to the generation of shearing force and rotational axis deviation as shown in FIGS. 12A and 12B in the joint 20. A deep mixing treatment machine 10 is used in which two or more arc-shaped concave portions are formed in a direction orthogonal to the traveling direction. When such a processing machine is used, the rotation directions of the adjacent stirring shafts 11 are opposite to each other, and therefore, it is sufficient that the number of axes is plural in the vertical direction (direction orthogonal to the traveling direction). Accordingly, the lateral direction (the same direction as the traveling direction) may be a single axis or a plurality of axes.

  Specifically, FIG. 9A uses a biaxial deep mixing processor 10 that has two axes in the longitudinal direction (direction orthogonal to the traveling direction) and one axis in the lateral direction (the same direction as the traveling direction). An example is shown, and in the process I, the advance improvement pile 17a is formed, and then the blanking portion 17c is formed while discharging water, and in the process II, the addition amount of the solidifying material 16 is increased and the subsequent process is performed. An improved pile 17b is placed.

  FIG. 9B shows an example in which a three-axis deep mixing processor 10 having three axes in the vertical direction (direction orthogonal to the traveling direction) and one axis in the horizontal direction (the same direction as the traveling direction) is used. In Step I, after forming the advancement improvement pile 17a, the blanking portion 17c is formed while discharging water, and in Step II, the added amount of the solidifying material 16 is increased and the subsequent improvement pile 17b is driven. Set up.

  FIG. 9C shows an example in which an eight-axis deep mixing processor 10 having two axes in the vertical direction (direction orthogonal to the traveling direction) and four axes in the horizontal direction (the same direction as the traveling direction) is used. In Step I, after forming the advancement improvement pile 17a, the blanking portion 17c is formed while discharging water, and in Step II, the added amount of the solidifying material 16 is increased and the subsequent improvement pile 17b is driven. Set up.

  In addition to the embodiments described above, it is only necessary to form two or more arc-shaped recesses in the direction orthogonal to the traveling direction, and the number of axes in the lateral direction (the same direction as the traveling direction) is uniaxial. Or a plurality of axes may be used.

  DESCRIPTION OF SYMBOLS 10 ... Deep mixing processing machine, 11 ... Stirring shaft, 12 ... Electric motor, 13 ... Stirring blade, 14 ... Cutting blade, 15 ... Injection pipe, 16 ... Solidification material, 17 ... Improvement pile, 17a ... Advance improvement pile, 17b ... Subsequent improvement pile, 17c ... empty casting part, 18 ... overlap part, 19 ... ground, 20 ... joint joint, 21 ... solidification improvement material.

Claims (6)

Excavate the ground with a drilling blade while rotating the stirring shaft of the deep mixing treatment machine, discharge the solidified material from the tip of the injection pipe, stir and mix with the stirring blade, create an improved pile, pull out the stirring shaft, In the construction method of the joint joint that moves the deep mixing treatment machine so as to have an overlap portion in the traveling direction and constructs a continuous wall by repeating the above operation,
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
Ri Do and a step of constructing a trailing improved pile remains idle driving portion,
Instead of solidifying material in the process of forming the idle portion, water is discharged to diffuse the overlap portion of the immediately preceding improved pile,
A joint joint construction method characterized in that the amount of water discharged is at least the amount of solidified material at the time of construction of the advanced improvement pile . Excavate the ground with a drilling blade while rotating the stirring shaft of the deep mixing treatment machine, discharge the solidified material from the tip of the injection pipe, stir and mix with the stirring blade, create an improved pile, pull out the stirring shaft, In the construction method of the joint joint that moves the deep mixing treatment machine so as to have an overlap portion in the traveling direction and constructs a continuous wall by repeating the above operation,
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
It consists of the process of constructing a follow-up improved pile on the trace of the empty part,
Instead of solidifying material in the process of forming the idle portion, water is discharged to diffuse the overlap portion of the immediately preceding improved pile,
In the case of clay soil, the amount of water discharged is limited to 15% with respect to 1 m ^{3 of} the solidified soil, and the joint strength is characterized in that the strength expression rate does not fall below 90% when water is not discharged. Ground construction method. Excavate the ground with a drilling blade while rotating the stirring shaft of the deep mixing treatment machine, discharge the solidified material from the tip of the injection pipe, stir and mix with the stirring blade, create an improved pile, pull out the stirring shaft, In the construction method of the joint joint that moves the deep mixing treatment machine so as to have an overlap portion in the traveling direction and constructs a continuous wall by repeating the above operation,
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
It consists of the process of constructing a follow-up improved pile on the trace of the empty part,
Instead of solidifying material in the process of forming the idle portion, water is discharged to diffuse the overlap portion of the immediately preceding improved pile,
The amount of water discharged is the amount of solidified material at the time of construction of the advanced improvement pile at the minimum,
In the case of clay soil, the amount of water discharged is limited to 15% with respect to 1 m ^{3 of} the solidified soil, and the joint strength is characterized in that the strength expression rate does not fall below 90% when water is not discharged. Ground construction method. Excavate the ground with a drilling blade while rotating the stirring shaft of the deep mixing treatment machine, discharge the solidified material from the tip of the injection pipe, stir and mix with the stirring blade, create an improved pile, pull out the stirring shaft, In the construction method of the joint joint that moves the deep mixing treatment machine so as to have an overlap portion in the traveling direction and constructs a continuous wall by repeating the above operation,
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
It consists of the process of constructing a follow-up improved pile on the trace of the empty part,
The process of constructing a follow-up improved pile on the trace of the blanked portion is an overlap portion between the preceding improved pile and the follow-up improved pile constructed on the trace of the blanked portion by increasing the solidification material more than the preceding improved pile. A joint joint construction method characterized by increasing the strength of the joint joint at the boundary . 5. The method for constructing joints according to claim 4 , wherein the additional amount of the solidifying material is set to 1.2 times the upper limit when the preceding improved pile is constructed. Excavate the ground with a drilling blade while rotating the stirring shaft of the deep mixing treatment machine, discharge the solidified material from the tip of the injection pipe, stir and mix with the stirring blade, create an improved pile, pull out the stirring shaft, In the construction method of the joint joint that moves the deep mixing treatment machine so as to have an overlap portion in the traveling direction and constructs a continuous wall by repeating the above operation,
A step of constructing a preceding improved pile using a stirring shaft having a plurality of axes in a direction orthogonal to the direction of continuous construction;
Before solidifying the immediately preceding advanced improvement pile, a step of forming a blank portion so as to have an overlap portion and diffusing the solidified material,
It consists of the process of constructing a follow-up improved pile on the trace of the empty part,
In the case of cohesive soil, the amount of water discharged in place of the solidified material during the step of forming the empty portion is limited to 15% with respect to 1 m ^{3 of} the solidified soil , and the strength expression rate is 90 when water is not discharged. %, And the amount of additional solidification material during the process of constructing a follow-up improved pile at the site of an empty cast part is 1.2 times the upper limit of the preceding improved pile as the upper limit. A joint joint construction method characterized in that the strength of the joint joint at the boundary in the overlap part between the pile and the follow-up improved pile built on the trace of the blank joint part is increased .

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