JP2008111240A - Method of constructing underground wall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of constructing an underground wall capable of smoothly advancing an entire construction operation by reducing a load for drilling by a multi-spindle excavator even if the ground is hard, stabilizing drilling positions and drilling directions, and preventing a portion with insufficient strength which may cause the spouting of pressurized water or damage to the underground wall from being produced. <P>SOLUTION: The portions 8 expected to be drilled by the separated spindles of the excavating spindle of a multi-spindle excavator are drilled beforehand by a single-spindle excavator having a drilling diameter smaller than the drilling diameter of the multi-spindle excavator to form preceding excavation holes 6. Then, these holes are drilled by the multi-spindle excavator, and the underground wall is constructed in the drilled holes with a soil cement. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for constructing underground walls having water-stopping performance such as soil cement continuous walls.

The soil cement continuous underground wall is made of soil cement columns in the ground by agitating the excavated soil and hardened material such as cement milk when excavating with an earth auger. It is made by construction. Various techniques relating to the construction method of such underground walls have been proposed, including the following patent documents.
JP 2005-220651 A JP 2002-363975 A

  A conventional excavation method for constructing a soil cement continuous wall according to FIG. 3 shows an auger 1, which is a screw excavation shaft 3 that is rotationally driven by a drive device 2 such as a hydraulic motor, as is well known. The excavation head 4 is used as the tip of the excavation head 4, and a hardening material such as cement milk passing through the inside of the excavation shaft 3 can be injected from the excavation head 4. In addition, although illustration is abbreviate | omitted, the drive device 2 is suspended from the leader mast of a base machine so that raising / lowering is possible, and the excavation axis | shaft 3 can be lengthened by adding suitably. Further, the screw of the excavation shaft 3 may be discontinuous.

  The sequential steps will be described. First, the auger 1 is positioned (A), the excavation head 4 of the excavation shaft 3 of the auger 1 is rotated forward, and drilling is started. At that time, the hardening material 5 such as sentiment milk and air are extracted from the excavation head 4 and injected into the hole (B).

  If the injection and drilling are continued to the predetermined depth while rotating forward in this way (C) (D), the pulling up is started, and the hardening material 5 is also injected at that time. This pulling is by forward / reverse rotation (E) in which forward rotation and reverse rotation are alternately repeated.

  If it is pulled up to a certain extent, excavation and agitation are performed again in the normal rotation and reverse rotation (F), and finally, the rotation is performed while rotating in the reverse rotation (G).

  In order to construct a continuous underground wall using soil cement in this way, when a single-axis excavator is used as the auger 1, excavation is performed first at intervals of every other as shown in FIG. Then, there are a method of excavating between the excavation holes and a method of connecting them one by one while sequentially overlapping them as shown in FIG. 5, and further, even with a multi-axis excavator as shown in FIG. Similarly, excavation is performed first with a gap of one unit (in the case of multiple axes, the number of continuous holes are formed), and then the method of drilling between these drill holes and illustration is omitted. However, there is a method of connecting excavation holes one unit at a time from the end.

  By the way, as shown in FIGS. 4 and 5, when drilling with a single-axis excavator, only one excavation hole can be formed at a time, and the work period is prolonged and work efficiency is poor. There is. In addition, the multi-axis excavator connects multiple excavation shafts so that the excavation shafts do not easily deviate from each other during excavation and the drilling direction is stable, whereas the single-axis excavator tends to deviate during excavation. There is also a problem. For this reason, when the underground wall is created by a single-axis excavator, the wall surfaces become uneven, and in some cases, the excavation holes are discontinuous and a continuous underground wall may not be obtained.

  On the other hand, when a multi-axis excavator is used, since a plurality of excavation shafts are connected, it is difficult for the excavation shafts to deviate from each other during excavation, and the drilling direction is stable and the walls are aligned. There is an advantage that a continuous underground wall can be created, and a plurality of continuous drilling holes can be made at a time, so that work efficiency is improved and a construction period can be shortened.

  The structure of a general multi-axis excavator is shown in FIG. 9 and FIG. In the multi-axis excavator, the excavation shaft 3 is connected downward to a drive mechanism 14 including a hydraulic motor and a speed reducer, and a plurality of excavation shafts 3 (five in the drawing) are arranged in parallel, and rods are arranged. Bundling was performed with a binding band 19 for steadying.

  The excavation shaft 3 is provided with an excavation head 4 at the tip, and an excavation blade 3a that also serves as a stirring blade with screw blades interrupted in the middle. Although not shown in the figure, the excavation shaft 3 is a hollow shaft through which a caking liquid such as cement milk flows and can be poured out from the discharge port of the excavation head 4.

  The drive mechanism 14 is supported by a wire from a top sheave 13 of a leader mast 12 standing on a base machine 11 such as a crawler while the excavation shaft 3 is connected. Further, the drive mechanism 14 engages the bending bracket 16 provided on the back surface with the leader 17 provided along the leader mast 12. In the figure, reference numeral 18 denotes a neck-like steady rest provided at the lower end of the leader mast 12, and the excavation shaft 3 penetrates vertically.

  In order to make the excavation holes by the excavation shafts 3 continuous, the excavation shafts 3 are arranged in parallel so that the excavation ranges of the adjacent excavation shafts 3 partially overlap each other. The excavation shafts 3 are alternately arranged before and after the excavation direction so as not to collide.

  In addition, in order to create a continuous underground wall, it is necessary to connect both ends of each unit of a continuous drilling hole formed by a single drilling hole of a multi-axis excavator. Since it is necessary to perform the next excavation after aligning the end of the excavation shaft 3 in parallel with the end of the hole, the excavation shaft 3 located on both sides of the excavation shaft 3 in parallel is arranged forward in the excavation direction, It is easy to align.

  In this way, by arranging a plurality of excavation shafts 3 in parallel on a straight line and bundling and fixing them together by the binding band 19, the multi-axis excavator is continuously excavated by the number of excavation shafts in one excavation. Drill holes can be formed.

  However, even though the multi-axis excavator is relatively stable in drilling direction when drilling, if the resistance from the ground such as hard ground is too great, the drilling position and drilling direction are likely to shift. End up.

  In order to avoid this, for example, as shown in FIG. 7, a single-axis excavator provided with an excavation shaft having the same diameter as the excavation shaft of the multi-axis excavator prior to the drilling by the multi-axis excavator (hereinafter referred to as main drilling). If drilling is performed by using this as a guide and the main drilling is performed as described above, the drilling shaft of the single-axis excavator is pivoted at the time of drilling compared to the drilling shaft of the multi-axis excavator as described above. Since the drilling site in the basement of the preceding excavation hole 6 is displaced from the drilling site on the surface of the ground, as a result, even if it is intended to drill in accordance with the planned drilling site of the main drilling hole, There is a problem of deviating from the range.

  And even if the underground wall 7 made of soil cement is formed in the excavation hole by the main drilling hole, the soil cement does not reach the leading excavation hole 6 at the portion that protrudes from the drilling portion of the main drilling hole and is solidified. Becomes insufficient, and a loose drilling body with insufficient strength remains as the remaining portion 6a. Then, the portion becomes a water path, and the pressurized water is ejected from the lower side of the underground wall 7 and there is a possibility that the water shielding effect cannot be expected.

  In addition, when the underground wall 7 is a retaining wall, the retaining wall is in close contact with the natural ground and resists earth pressure on the back side (active side, lower side in the figure). When excavation work is carried out with the loose drilling body from the previous drilling hole left inside (the passive side, the upper side in the figure), a part of the underground wall 7 is loose due to insufficient vibration due to the vibration of the work. It is assumed that it moves toward the remaining portion 6a, the crack 9 is generated and damaged in the underground wall 7 of that portion, and the groundwater on the back side of the earth retaining wall is ejected therefrom.

  Further, if only one preceding drilling hole is made, even if one drilling shaft of the drilling shaft of the multi-axis excavator is inserted into the preceding drilling hole 6 in this drilling hole, There is also a possibility that the entire excavation shaft is displaced in the rotational direction, and it is not sufficient to guide the drilling position.

  In addition, the multi-axis excavator drills using multiple drilling shafts at the same time, so the resistance received from the ground during drilling increases. Especially when drilling hard ground, a heavy load is applied to the drilling shaft. Therefore, the drilling operation may be difficult.

  The present invention eliminates the inconveniences of the conventional example, stabilizes the drilling position and drilling direction even on hard ground, reduces the drilling load by the multi-axis excavator, and allows the entire construction work to proceed smoothly. And it aims at providing the construction method of the underground wall which does not produce the part of insufficient intensity | strength causing the ejection of pressurized water and the breakage of an underground wall.

  In order to achieve the above object, the underground wall construction method of the present invention is, firstly, a multi-axis excavation in which a plurality of excavation shafts are provided alternately in the front and rear in the excavation direction, and the excavation shafts on both sides are arranged in front of the excavation direction. Using the single-axis drilling machine with a drilling diameter smaller than the drilling diameter of the machine, after pre-drilling the planned drilling site for each separated axis of the drilling shaft of the multi-axis drilling machine, The main drilling hole is inserted by inserting the side drilling shaft, and this is repeated to make all the drilling holes continuous, and the underground wall with soil cement or the like is created in the drilling hole. The gist of the present invention is to inject an injection solution in which cement or bentonite is mixed with water.

  According to the first aspect of the present invention, since excavation is performed by inserting the excavation shafts on both sides of the multi-axis excavator into the preceding excavation hole, at least two of the excavation shafts on both sides are inserted during the main drilling. The preceding excavation hole serves as a guide, and the excavation shafts arranged in parallel do not shift in the rotation direction, and the drilling position and direction of the main drilling hole can be effectively stabilized.

  And at the time of drilling, by inserting the drilling shafts on both sides located in front of the drilling direction into the preceding drilling hole, the leading drilling of the single-axis drilling machine with less load when drilling compared to the multi-axis drilling machine Since the ground that has been loosened by drilling is drilled, even when drilling hard ground, the load applied to the multi-axis excavator can be effectively reduced during drilling, and the drilling operation can be performed smoothly. Can do.

  In other words, during drilling, when the drilling shaft arranged in front of the drilling direction among the drilling shafts of the multi-axis excavator drills, the area around the drilling hole already loosened by the preceding drilling is expanded. Thus, since the digging proceeds, the load on the excavation shaft can be reduced. Further, when the drilling shaft behind the excavation direction is subsequently drilled, the drilling range is partially the same as the drilling range loosened by drilling first by the drilling shaft arranged in front of the excavation direction. Since they overlap, the load applied to the excavation shaft can be reduced, and the entire load during the main excavation can be effectively reduced.

  Furthermore, the load applied to the excavation shaft during the preceding drilling can be reduced by reducing the diameter of the preceding drilling hole, and the preceding drilling itself can be performed smoothly. In addition, if the pre-drilling of all drilling shafts in a multi-axis excavator is performed in advance, the labor required for the previous drilling becomes large and the work efficiency is not good. Since it is set for every separated axis of the planned drilling portion of the excavator, the work efficiency as a whole is improved by minimizing the labor required for the preceding drilling. And by these synergistic effects, the whole construction work can proceed smoothly.

  And since the drilling diameter of the preceding drilling hole is smaller than the drilling diameter of the main drilling hole, even if the shaft is slightly deviated during the preceding drilling, the range of the preceding drilling may protrude from the drilling range of the main drilling. In addition, the protruding portion remains as a loose drilling body with insufficient strength, so that the blowout of pressurized water and the breakage of the underground wall are not caused.

  According to the second aspect of the present invention, the excavated soil by the preceding drilling hole is mixed with the injection liquid to increase the fluidity, thereby reducing the load at the time of the preceding drilling, and the book to be performed thereafter. A soil cement body can be formed smoothly by mixing a caking material such as drilling holes and cement milk with excavated soil.

  In addition, when the amount of cement contained in the injected solution is kept low so that the injected solution does not solidify before the main excavation, the strength of the part obtained by consolidation of the mixture of the injected solution and the excavated soil is However, since the range of the preceding drilling hole does not protrude from the range of the main excavation, a loose part with insufficient strength does not remain.

  In addition, the amount of injected liquid used can be reduced by reducing the diameter of the preceding hole, and the amount of mixed agitation mud discharged between the injected liquid and excavated soil discharged during drilling can also be reduced. Therefore, the load on the surrounding environment can be suppressed, and the cost required to dispose of the mixed stirred mud as industrial waste can also be reduced.

  As described above, the underground wall construction method of the present invention reduces the load of drilling by a multi-axis excavator even on hard ground, and can smoothly proceed with the entire construction work. The direction is stabilized, and there is no occurrence of an insufficiently-strength portion that causes ejection of pressurized water and breakage of the underground wall.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a first step showing an embodiment of the underground wall construction method of the present invention.

  In FIG. 1, the planned drilling location of the multi-axis excavator is indicated by a one-dot chain line. In the first step, the planned drilling location 8 for each separated axis of the multi-axis drilling machine is changed to cement and bentonite. A pre-drilling hole 6 is formed by drilling with a single-axis excavator (hereinafter referred to as a pre-drilling hole) while injecting an injection solution mixed with water. The excavation axis of the single-axis excavator is set smaller than the excavation axis of the multi-axis excavator.

  Note that the cement mixing ratio of the injected liquid is set to be small so that the inside of the preceding excavation hole 6 does not solidify until the next main excavation is performed.

  In the next second step, this drilling is performed while injecting a cemented material such as cement milk from the tip of the multi-axis excavator. Although not shown, each drilling shaft of the multi-axis excavator can be connected to each other by partially overlapping each other's drilling range, so that the drilling heads do not collide with each other. The tip position is provided by shifting the front side and the rear side, but the excavation shaft located on the front side is drilled in accordance with the position of the preceding drilling hole.

  Thereby, at the time of the main drilling, at least two preceding drilling holes 6 into which the drilling shafts 3 on both sides are inserted serve as guides, and the parallel drilling shafts are not displaced in the rotation direction, and the drilling position of the main drilling holes And the drilling direction can be stabilized effectively.

  In addition, this allows the front excavation shaft to dig so as to expand around the previously advanced excavation hole 6, so that the load on the excavation shaft can be reduced. Further, since the drilling range of the rear excavation shaft to be drilled subsequently overlaps with the drilling range loosened by the drilling by the front excavation shaft, the load on the rear excavation shaft is also reduced. It is possible to reduce, and the entire load during this drilling can be effectively reduced.

  In this drilling hole, as in the conventional example, the consolidation material is injected and stirred simultaneously with the drilling. That is, the excavation shaft is rotated forward to start drilling. At that time, a caking material such as sentiment milk and air are extracted from the excavation head and injected into the hole, and after drilling to a predetermined depth, the solidification is still performed. While injecting the binder, the excavation shaft starts to be lifted while repeating forward rotation and reverse rotation alternately. And if it raises to some extent, excavation and agitation are performed again in the normal rotation and reverse rotation, and finally, the pulling is performed while reverse rotation.

  FIG. 2 shows a cross-sectional plan view of the underground wall constructed in this way. In the figure, 7 indicates the underground wall. As the drilling by the single-axis excavator sways, the preceding drilling hole 6 will deviate from the position aligned on the ground surface, as indicated by the alternate long and short dash line. Since it is smaller than the drilling diameter, it does not protrude from the drilling range of the present drilling hole.

  For this reason, the portion where the preceding excavation hole 6 protrudes from the drilling range of the main drilling hole remains as a loose drilling body with insufficient strength, so that the discharge of pressurized water and the breakage of the underground wall 7 are not caused.

  Moreover, the ratio of the drilling area when the drilling diameter of the preceding drilling hole is the same as that of the main drilling hole and when the drilling hole diameter is smaller than that is shown in FIG. As a result, the amount of the injection solution used during the previous drilling can be reduced. For example, when the drilling diameter of the main drilling hole is 1000 mm and the drilling diameter of the preceding drilling hole is 850 mm, the amount of the injection liquid used at the time of the previous drilling is the same as the drilling diameter of the main drilling hole. 72.2% of the case where it is the same.

  In addition, if the drilling diameter of the preceding drilling hole is reduced, the amount of mixed stirring mud discharged from the injected liquid and excavated soil generated during the previous drilling can be reduced, which makes it possible to dispose of mixed stirring mud as industrial waste. Such costs can be reduced.

  As another embodiment, cement may not be used for the injection liquid at the time of prior drilling, but cement may be used only at the time of final drilling. Thereby, it is not necessary to make the excavated soil discharged at the time of preceding drilling into industrial waste containing cement.

  Also, the excavated soil is discharged from the excavated hole at one end, and the excavated soil is mixed with cement milk in an amount sufficient to obtain the amount of soil cement necessary for the construction of the underground wall, and then filled into the excavated hole. good. Even with this method, the excavated soil that has not been mixed with cement milk does not become industrial waste.

It is a top view of the 1st process which shows the 1st Example of the construction method of the underground wall of this invention. It is a cross-sectional top view which shows the underground wall in a basement. It is explanatory drawing which shows a prior art example. It is explanatory drawing which shows an example of the construction procedure of a underground wall. It is explanatory drawing which shows the other example of the construction procedure of a underground wall. It is explanatory drawing which shows the further another example of the construction procedure of a underground wall. It is a cross-sectional top view which shows the underground wall from which the preceding drilling position shifted | deviated in the underground. It is a table | surface which shows the ratio of the drilling area at the time of changing the drilling diameter of a preceding drilling hole. It is a front view of a multi-axis excavator. It is a side view of a multi-axis excavator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Auger 2 ... Drive apparatus 3 ... Excavation shaft 3a ... Excavation blade 4 ... Excavation head 5 ... Hardening material 6 ... Precise excavation hole 6a ... Residual location 7 ... Underground wall 8 ... This drilling planned location 9 ... Crack 11 ... Base Machine 12 ... Leader mast 13 ... Top sheave 14 ... Drive mechanism 16 ... Curved bracket 17 ... Leader 18 ... Stabilizer 19 ... Cable tie

Claims (2)

  Excavation of a multi-axis excavator with a single-axis excavator having a drilling diameter smaller than the drilling diameter of a multi-axis excavator in which a plurality of excavating axes are provided alternately in front and rear in the excavating direction and the excavating shafts on both sides are arranged in front of the excavating direction After pre-drilling the planned drilling location for each axis of the shaft, the drilling shafts on both sides of the multi-axis excavator are inserted into this advanced drilling hole, and this drilling is repeated to repeat all drilling holes. In addition, the underground wall construction method is characterized in that the underground wall is made of soil cement or the like in the excavation hole.   The construction method of the underground wall of Claim 1 which inject | pours the injection liquid which mixes cement and bentonite with water to a preceding excavation hole.

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