JP4916758B2 - Ground improvement method by high-pressure jet agitation - Google Patents

Description

  The present invention relates to a ground improvement method by high-pressure jet stirring.

Conventionally, when it is necessary to improve the ground when installing a new structure in the ground below the existing structure or facility, it may not be possible to perform construction from the ground. There is a case where the ground is improved horizontally from here (see, for example, Patent Document 1).
Japanese Patent No. 2647572

However, in the case of drilling in the horizontal direction, when performing the injection method or the high-pressure injection method, the formed tube used is relatively thin with a diameter of about 40 to 150 mm. It is inevitable that the accuracy of straightness also decreases.
That is, particularly in soft ground, the drilled pipe (or self-drilling tube) is always bent downward by the weight of the tip and the drilled tube (or self-drilled tube) itself, and the drilling length is reduced. The longer it is, the greater the bending of the hole (the hanging of the hole). As a result, as shown in FIG. 11, the position of the improved body may increase or become a bow, making it impossible to improve the target position. In addition, if the drilled pipe (or self-piercing type formed pipe) has a bow shape, the ground resistance at the time of rotation increases, which causes jamming. Furthermore, unlike the case of rotating while maintaining straight advanceability, a hole is drilled while greatly breaking the surrounding ground, causing a risk that the range of loosening of the ground is widened.
Also, when drilling and creating the entire length at a stretch when performing construction at long and deep depths, the continuous work time becomes too long, it is difficult to take over work by changing workers, and the risk of troubles increases. Furthermore, since the working time is increased, there is a problem that the cost is increased due to an increase in labor cost.
Accordingly, the main problem of the present invention is that in the ground improvement method by high-pressure jet agitation in the horizontal direction, the accuracy of straightness of the improved body is maintained by minimizing the bending of the hole during drilling, and the work efficiency is improved. Another object of the present invention is to propose a ground improvement method that reduces the risk of troubles associated with work transfer and reduces costs.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
The invention according to claim 1 is a state in which the formation pipe is inserted into the ground along the substantially horizontal direction from the shaft , and the high pressure grout is injected through the formation pipe or the high pressure water is injected and the grout is injected. Or in combination with this, it is a ground improvement method by high pressure jet stirring that jets compressed air and stirs and mixes grout to create an improved body around the pipe,
While extracting and rotating the above-mentioned forming tube inserted up to a predetermined depth, the grout is sprayed at high pressure, the ground is cut and mixed with stirring, and the surrounding area is improved to create a section of improved body,
After the preceding improvement body has obtained a predetermined compressive strength, the preceding improvement body is drilled in advance for a predetermined length from the base end side,
Using the pre-drilled hole as a guide, insert the created tube to a predetermined depth in a new next improved section on the unimproved side,
After that, the grouting tube is pulled and rotated while being pulled out, and the grouting is sprayed at high pressure, and the ground is cut and mixed with stirring to improve the surrounding area and create an improved body in the next improved section, and connect to the preceding improved body. Repeat the process sequentially,
It is a ground improvement method by high-pressure jet agitation characterized in that an improved body is formed over the entire length while sequentially creating improved bodies divided into a predetermined length.

<Invention of Claim 2>
Invention of Claim 2 is the ground improvement construction method by the high-pressure jet stirring of Claim 1 whose length of the improvement body of one division divided and created is about 5-20m.

(Function and effect)
By constructing the improved body over the entire length while sequentially creating the improved body divided into a predetermined length, the deformation of the formed pipe can be kept to a minimum compared to creating the improved body at once without splitting. The accuracy of the straightness of the improved body can be maintained. In addition, after the preceding improved body has obtained a predetermined compressive strength, the process of creating a new improved body on the unmodified side of the inner part in contact with the deepest part of the improved body is sequentially repeated, so that it is always hard and stable. Since the ground is drilled, the bending of the hole (dangging of the hole) can be kept to a minimum even when the unmodified portion is drilled, and the straightness accuracy of the improved body can be maintained.
In order to maintain the accuracy of the straightness of the improved body, if the predetermined length of one improved body that is divided and formed is about 5 to 20 m, the work can be taken over smoothly by changing the workers. Therefore, it is possible to reduce the risk of troubles due to work takeover and to reduce costs by shortening the work time.

<Invention of Claim 3>
The invention according to claim 3 is a first step of drilling the ground to create an improved body, and an improved body formed by the first step is configured to perform percussion drilling or direction control by a drilling tube. A second step of performing a possible drilling and forming a guide hole for inserting a forming tube for forming an unmodified portion, and sequentially repeating these first step and second step, It is the ground improvement construction method by the high-pressure jet stirring of Claim 1 or 2 which builds an improved body over the full length.

(Function and effect)
In the second step, a guide for inserting a formed tube for forming an unimproved portion by performing a striking-type drilling or a direction-controllable drilling on the improved body formed in the previous step. If the hole is formed, the striking-type hole or the hole whose direction can be controlled is excellent in straightness, and therefore, in the next step (first step), it is possible to make a drilled tube with excellent straightness. .

<Invention of Claim 4>
The invention described in claim 4 includes a first step of injecting a chemical solution in advance so that the ground has a predetermined compressive strength prior to drilling for the improvement body, and an injection in advance by the first step. A second step of creating an improved body by high-pressure jet agitation with respect to the ground, and the first step and the second step are sequentially repeated to create an improved body over the entire length. Or it is the ground improvement construction method by the high-pressure jet stirring of 2.

(Function and effect)
In the first step, prior chemical injection is performed and the ground is drilled, thereby preventing jamming during drilling with the created pipe and preventing the ground from collapsing. Further, it is possible to prevent the bending of the hole at the time of drilling. It should be noted that prior chemical injection in the first step is effective when used on soft ground with high groundwater level, especially in sandy soil. However, it may be performed so as not to cause jamming.

<Invention of Claim 5>
The invention according to claim 5 includes a first step of injecting a chemical solution in advance so that the ground has a predetermined compressive strength prior to drilling for the improvement body, and an injection in advance by the first step. A second step of creating an improved body by high-pressure jet stirring with respect to the ground thus obtained, and a drilling hole or a direction-controllable drilling hole for the improved body formed by the second step by a drilling tube And a third step of forming a guide hole for inserting a forming tube for forming an unmodified portion, and sequentially repeating the first step, the second step, and the third step. The ground improvement method by high-pressure jet stirring according to claim 1 or 2, wherein an improved body is formed over the entire length.

(Function and effect)
In the first step, prior chemical injection is performed and the ground is drilled, thereby preventing jamming during drilling with the created pipe and preventing the ground from collapsing. Further, it is possible to prevent the bending of the hole at the time of drilling. It should be noted that prior chemical injection in the first step is effective when used on soft ground with high groundwater level, especially in sandy soil. However, it may be performed so as not to cause jamming.
Also, in the third step, the improved body formed in the second step is subjected to percussion type drilling or direction controllable drilling with a drilling tube, and a formed tube for creating an unmodified portion is inserted. If the guide hole for forming is formed, the striking-type hole or the hole whose direction can be controlled is excellent in straight advancement, and therefore, in the next step, it is possible to make a formed pipe excellent in straight advancement.

  According to the present invention, in the ground improvement method by high-pressure jet stirring in the horizontal direction, the accuracy of straightness of the improved body is maintained by minimizing the bending of the hole during drilling, and the work efficiency is improved. There are advantages such as reducing the risk of troubles caused by work transfer and reducing costs.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a shaft is excavated in the ground G, and the side surface of the ground G is supported by earth retaining 91 such as an underground continuous wall. From the inside of the vertical shaft 90 blocked by the earth retaining 91, the ground pipe G is drilled by the forming pipe 1 and the ground G is improved by high-pressure jet agitation. As shown in FIG. Divided into a plurality of stages in the direction (for example, 2 to 5 stages), the length of one stage is about 5 to 20 m, and the stage on the front side of the shaft 90, which is the first stage, is improved. After the value is obtained, the next stage is drilled and improved, and all stages are improved by repeating this process in sequence.

  Here, the forming pipe 1 used in the present invention has, for example, a self-piercing double pipe structure in which a bit (not shown) or the like is formed at the tip, and is configured by appropriately connecting unit pipes. As the forming tube 1, one having a diameter of about 100 mm is used. Further, as shown in FIG. 1, an injection window 10 which is a communication port is provided on the peripheral wall of the tip, and the grout is grouting from the injection window 10 by an injection nozzle 10a while rotating the forming tube 1 around the axis. Or grout is injected while jetting high pressure water, the ground G is cut, and the cut soil and grout are stirred and mixed. By this stirring and mixing, a substantially cylindrical improvement body 100 with the forming tube 1 as an axis is formed. In addition, if the formation pipe | tube of a triple pipe structure is used, it can cut with the compressed air of high pressure water, and it is also possible to fill grout with a high pressure or a low pressure. In addition, about the magnitude | size of the diameter of the forming pipe 1, it is not limited to said numerical value.

  Examples of the grout include cement milk, cement clay, and cement lime, and those obtained by adding fine particles such as fly ash, slag, bentonite, and the like. Further, as grout auxiliary materials, for example, quick setting agents such as water glass, calcium chloride, aluminum hydroxide, calcium sulfoaluminate (CSA), separation inhibitors, dispersants, foaming agents, foaming agents, etc. Can be used.

  In the above injection operation, the mud pipe 2 is inserted substantially horizontally with respect to the ground G so that the base end portion thereof is located in the shaft 90. This insertion may be performed along the upper end of the part where the improved body 100 (and 200,...) Is formed. An intake window 20 serving as a communication port is provided on the peripheral wall of the distal end portion of the mud discharge pipe 2, and the cutting mud in the ground G is discharged through the intake window 20 using the internal pressure of the improved portion. It is taken into the mud pipe 2 and stored in a storage tank (not shown) installed in the shaft 90 through the mud pipe 2.

  In the ground improvement method according to the present invention, first, the mouth apparatus 4A, 4B is attached to the earth retaining plate 91 as shown in FIG. In addition, when it is necessary to give a gradient according to the ground condition, an angled mouth device can be used as the mouth device.

Next, in the case of a soft ground with a high groundwater level, especially sandy soil, a pre-injection work is performed before the improvement body construction work as shown in FIG. Specifically, as a pre-injection work for the stage 1, after attaching the mouth devices 4A and 4B, the self-drilling type injection pipe 30 (about 40 mm in diameter) is placed in the mouth devices 4A and 4B for the respective forming pipes and drainage pipes. The ground G is drilled to a predetermined length (for example, about 7 m). Here, when drilling an unimproved portion (ground to be improved), it is preferable to use a stabilizing liquid such as bentonite mud water for drilling water because jamming can be prevented. While pulling out the injection tube 30 toward the front, as shown in FIG. 3, a chemical solution is injected to stabilize the natural ground. For loose sandy ground, which is easy to collapse, if a chemical solution with relatively low strength (compression strength after injection: about 0.02 to 0.2 MN / m ² ) is injected beforehand, This is because jamming is prevented and the ground is prevented from collapsing. As a result, it is possible to prevent bending of the forming pipe 1 and the sludge pipe 2 when drilling. Moreover, since it is not too strong as a strength, drilling can be easily performed.

  The pre-injection range may be a substantially cylindrical cross-sectional diameter of about 0.5 to 1 m around the axis of the injection tube 30. As the chemical solution, it is desirable that the earth and sand be separated during cutting stirring by high pressure injection.

  In addition, as an injection method, after drilling to the front-end | tip of a predetermined depth, you may inject | pour while pulling out the injection tube 30, and you may inject | pour while drilling. As described above, this pre-injection work prevents the collapse of the natural ground, stabilizes the natural ground, and minimizes the bending of the hole during drilling, which is a subsequent process, so that the improved body 100 to be formed later is formed. Has the role of improving the accuracy of straightness. It also has the effect of preventing jamming and preventing collapse of surrounding ground. As described above, the pre-injection work is performed in a soft ground with a high groundwater level, especially in the case of sandy soil, and thus is not necessary depending on the ground condition.

  Next, as shown in FIG. 4, as the drilling work and improved body construction work of the stage 1, as shown in FIG. Drilling with a self-drilling type mud pipe 2 equipped with When the drilling hole reaches a predetermined depth, as shown in FIG. 5, the grout is high-pressure jetted while being rotated while being pulled out, and the ground is cut and stirred to improve the surroundings, as shown in FIG. 6. Then, the improved body 100 is formed. Here, an improved body is formed by high-pressure jet stirring while pulling out the forming pipe 1 and the sludge pipe 2 from the deepest part of the divided target ground (stage 1), and after completion, the gate valves of the mouth apparatus 4A, 4B are turned on. Close and prevent injected grout and mud from leaking out of mouth. The improved body 100 may have a substantially cylindrical cross-sectional diameter of about 2 m with the axis of the forming tube 1 as the center.

Next, after the compressive strength of the improved body 100 reaches about 0.2 MN / m ² or more, as shown in FIG. 7, a bit (not shown) is provided at the tip as the preceding drilling work of the stage 2. The drilled pipe 5 is drilled with percussion (not shown). It is preferable that the drilling is performed from the tip of the improved body 100 formed by the above-described improved body construction work to a portion about 0.5 to 1 m in front. Here, the reason why the hole is drilled by percussion is that it is superior in straightness as compared with the case where the hole is drilled by rotating with a rotary drill. A drilling tube 5 having a slightly larger diameter is used. The larger the bore diameter of the drilled pipe 5, the better the straightness, but if it is too larger than the formed pipe 1, the pipe hangs downward, so that the difference in the pipe diameter is suitably 50 mm or less. The straightness can be improved by inserting the injection tube 30 and the forming tube 1 used in the next stage while using the injection hole thus formed as a guide.

  In addition, it may replace with said striking-type drilling, and may drill with a drilling machine provided with the drilling tube in which direction control is possible. This is because of course excellent straightness.

  Moreover, about the drainage hole into which the drainage pipe 2 is inserted, the drilling pipe 5 may be pre-drilled by percussion (not shown) and inserted into the hole, but it is not always necessary.

  The preceding drilling is preferably performed in order to improve the straight accuracy of the drilling in the next stage pre-injection, drilling, and improved body construction.

  Thereafter, the drilling tube 5 is pulled out, and the formed hole functions as a guide hole, and as a pre-injection work for the stage 2, a self-drilling type injection tube 30 is inserted as shown in FIG. While digging up to a predetermined length (for example, about 12 m) in the tip direction from the hole drilled by drilling and improvement body construction, injection is performed on the surrounding ground, with the axis of the injection tube 30 as the center Improve the surrounding area by infiltrating about 1m in cross-sectional diameter. In addition, as an injection | pouring method, after making a hole first, you may inject | pour a chemical | medical solution, drawing out the injection tube 30, or you may inject | pour while drilling.

  Next, after the range of about 1 m in diameter around the hole formed by the pre-injection process of the stage 2 is improved, self-drilling is performed for each hole as a drilling process and an improved body creation process of the stage 2 With the mold forming pipe 1 and the self-drilling type mud pipe 2, it is inserted to the tip of the improved body while drilling. Next, as shown in FIG. 9, the grout is injected at high pressure while rotating the forming tube 1, and the ground is cut and stirred to improve the surroundings, thereby forming the improved body 200. Here, an improved body is formed by high-pressure jet stirring while pulling out the forming pipe 1 and the sludge pipe 2 from the deepest part of the divided target ground (stage 2), and after completion, the gate valves of the mouth apparatus 4A, 4B are turned on. Close and prevent injected grout and mud from leaking out of mouth.

  Next, as shown in FIG. 10, a drilling pipe 5 provided with a bit (not shown) at the tip is drilled by percussion (not shown) as a preceding drilling work for the stage 3. The drilling is performed from the tip of the improved body 200 formed by the above-described improved body construction work to a portion about 0.5 to 1 m in front.

  As described above, as shown in FIG. 11, stage 3, stage 4,... And pre-injection work (unnecessary depending on the ground condition), drilling work and improved body creation work, preceding drilling work (unnecessary depending on the ground condition) You can improve all the stages by repeating the above. In this way, in order to improve the ground at a long depth, it is divided into a plurality of stages in the horizontal direction (for example, 2 to 5 stages), and the length of one stage is set to about 5 to 15 m, before the shaft 90 as the first stage. After improving the stage on the side and obtaining the value of the improved strength above a certain level, the next stage is drilled and improved, and all stages are improved while repeating the steps in order, There are advantages.

  That is, the entire length of the portion to be improved is divided into a plurality of stages, and the drilling length of each stage is as short as about 5 to 20 m. Therefore, compared with the case where the improved body is formed at a stretch without dividing, Deflection is also minimized and the accuracy of straightness of the improved body can be maintained.

  In addition, by injecting a chemical solution in advance to the target ground of the unimproved portion, it is easy not only to obtain straightness in the forming pipe 1 and the mud pipe 2, but also in the case of drilling with the forming pipe 1 and the mud pipe 2 The jamming of the ground can be prevented and the collapse of the ground can be prevented.

  Further, the improved body formed in the previous step is subjected to a striking-type drill or a hole whose direction is controllable by a drill pipe 5 having a slightly larger diameter than the formed pipe 1 to create an unmodified part 1. If the guide hole for inserting the hole is formed, the striking-type hole or the hole whose direction can be controlled is excellent in straightness, and therefore, in the next step, the formed pipe 1 and the sludge pipe having higher straightness. Two holes can be drilled.

It is a longitudinal cross-sectional view which shows the arrangement | positioning relationship of the formation pipe and sludge pipe used for the ground improvement construction method which concerns on this invention. It is a longitudinal cross-sectional view for demonstrating the mouth apparatus installation work in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the pre-injection work (stage 1) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the drilling work (stage 1) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the improvement body construction work (stage 1) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the improved body created by the improved body construction work (stage 1) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the preceding drilling work (stage 2) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the pre-injection work (stage 2) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the improvement body construction work (stage 2) in a ground improvement construction method. It is a longitudinal cross-sectional view for demonstrating the preceding drilling work (stage 3) in a ground improvement construction method. It is a longitudinal cross-sectional view which shows the outline | summary of the improvement body formed by the ground improvement construction method which concerns on this invention, and the conventional improvement body example.

  DESCRIPTION OF SYMBOLS 1 ... Construction pipe, 2 ... Drainage pipe, 4A, 4B ... Mouth device, 5 ... Drilling pipe, 10 ... Injection window, 10a ... Injection nozzle, 20 ... Intake window, 30 ... Injection pipe, 90 ... Vertical shaft, 91 ... Earth retaining, 100, 200 ... improved body, G ... ground.

Claims (5)

With the construction pipe inserted from the shaft along the horizontal direction in the ground, high pressure grout is injected through this construction pipe, or grout is injected while injecting high pressure water, or in combination with this, compressed air A ground improvement method by high-pressure jet agitation, in which the grout is agitated and mixed to create an improved body centering on the constructed pipe,
While extracting and rotating the above-mentioned forming tube inserted up to a predetermined depth, the grout is sprayed at high pressure, the ground is cut and mixed with stirring, and the surrounding area is improved to create a section of improved body,
After the preceding improvement body has obtained a predetermined compressive strength, the preceding improvement body is drilled in advance for a predetermined length from the base end side,
Using the pre-drilled hole as a guide, insert the created tube to a predetermined depth in a new next improved section on the unimproved side,
After that, the grouting tube is pulled and rotated while being pulled out, and the grouting is sprayed at high pressure, and the ground is cut and mixed with stirring to improve the surrounding area and create an improved body in the next improved section, and connect to the preceding improved body. Repeat the process sequentially,
A ground improvement method by high-pressure jet agitation characterized in that an improved body is formed over the entire length while sequentially creating improved bodies divided into predetermined lengths.   The ground improvement method by high-pressure jet agitation according to claim 1, wherein the length of the divided improvement body formed by dividing is about 5 to 20 m. A first step of drilling the ground to create an improved body;
The improved body formed by the first step is subjected to a striking-type drill or a hole whose direction is controllable by the drill pipe, and a guide hole for inserting the formed pipe for creating the unmodified part is formed. A second step,
The ground improvement method by high-pressure jet agitation according to claim 1 or 2, wherein the first and second steps are sequentially repeated to form an improved body over the entire length. A first step of injecting a chemical solution in advance so that the ground has a predetermined compressive strength prior to drilling for the improvement body;
A second step of creating an improved body by high-pressure jet stirring on the ground previously injected by the first step;
The ground improvement method by high-pressure jet agitation according to claim 1 or 2, wherein the first and second steps are sequentially repeated to form an improved body over the entire length. A first step of injecting a chemical solution in advance so that the ground has a predetermined compressive strength prior to drilling for the improvement body;
A second step of creating an improved body by high-pressure jet stirring with respect to the ground previously injected in the first step;
The improved body formed by the second step is subjected to a striking-type hole or a hole whose direction is controllable by the hole tube, and a guide hole for inserting the tube that forms the unimproved portion is formed. A third step,
The ground improvement method by high-pressure jet stirring according to claim 1 or 2, wherein the first step, the second step, and the third step are sequentially repeated to form an improved body over the entire length.

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