JP2006336282A - Natural ground reinforcing method, and prepared hole boring bit for use therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a natural ground reinforcing method including a prelining method and a mirror portion reinforcing method, for reinforcing the natural ground in front of a working face during excavation of a tunnel, wherein a consolidation agent is prevented from leaking, to thereby easily and positively achieve reinforcement of the natural ground, and to provide a prepared hole boring bit for use in the method. <P>SOLUTION: According to the natural ground reinforcing method, a stepped prepared hole h consisting of a first borehole portion h1 having a diameter almost equal to that of a drilled hole for driving a reinforcing pipe 1 therein, and a second borehole portion h2 concentric with the first borehole portion h1 and having a diameter larger than that of the first borehole portion h1, is formed in the natural ground. Thereafter, a drilled hole H having a diameter almost equal to that of the first borehole portion is further formed in the natural ground in a manner extending the first borehole portion h1, and at the same time the reinforcing pipe 1 is driven into the drilled hole H. Then, a sealing means 20 is interposed between a rear end external surface of the reinforcing pipe 1 and an internal surface of the second borehole portion h2, and thereafter the interior of the reinforcing pipe 1 and the natural ground around the same are filled with the consolidation agent 1 via the reinforcing pipe 1, to thereby achieve reinforcement of the natural ground. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is, for example, through a ground reinforcement method such as a so-called receiving construction or mirror reinforcement work for reinforcing the ground in front of the face during tunnel excavation, in particular, through a reinforcement pipe placed in the ground by a double pipe drilling method or the like. In particular, the present invention relates to a natural ground reinforcing method for reinforcing a natural ground by filling a solidified material in the reinforcing pipe and the surrounding natural ground, and a pilot hole forming bit used therefor.

  Conventionally, for example, a double pipe cutting in a ground reinforcement method such as a leading construction A or a mirror part reinforcement construction B for reinforcing the front ground G of the face f when excavating the tunnel T as shown in FIGS. At the same time as drilling, a reinforcing pipe having a large number of through holes in the peripheral surface is placed in the drilling hole, etc., and a solid material g is filled in the surrounding natural ground through the reinforcing pipe. What reinforces a mountain is known (see Patent Document 1 below).

  FIG. 10 shows an example of a specific process up to placing a reinforcement pipe in the above-described ground reinforcement method. First, as shown in FIG. A pilot hole h having a diameter larger than that of the reinforcing pipe is drilled from the predetermined position toward the front ground mountain G by a depth of about 300 mm. Next, a drilling hole H is formed from the lower hole h by a double pipe drilling method or the like, and at the same time, a reinforcing pipe is driven into the drilling hole. In the case of the figure, as shown in FIG. A drill bit 3 is rotatably provided at the tip of a reinforcing tube 1 having a large number of through holes 1a through a casing shoe 2 and the like, and the tip of the drill rod 4 inserted into the reinforcing tube 1 is connected to a bit adapter. In a state of being engaged with the drill bit 3 via 5, the drill bit 3 is rotated together with the drill rod 4.

  As a result, the hole H is formed in the ground G, and at the same time, the reinforcing tube 1 is driven into the hole H. At that time, the hole 4 and the reinforcing tube 1 are usually Each formed to a predetermined length is successively added with a coupler or the like. When the hole is drilled to a predetermined depth and the reinforcing tube 1 having a predetermined length is drawn into the hole H and driven, the drilling rod 4 and the bit adapter 5 are pulled out and collected. The bit 3 is left in the hole H.

  Next, the space inside the reinforcing pipe 1 is used to inject and fill the solidified material into the reinforcing pipe and the surrounding natural ground. As the injection method, for example, as shown in FIG. Such a step injection method and a simultaneous injection method as shown in FIG. That is, FIG. 11 (a) divides the inside of the reinforcing tube 1 into a plurality of chambers by a packer 6 or the like, and sequentially injects the consolidated material into each chamber via an injection hose 7 or the like. In this case, by injecting a chemical solution into the packer 6 from the packer injection hose 9, both ends in the longitudinal direction of the packer 6 are inflated to adhere to the inner surface of the reinforcing tube 1, and the chemical solution is supplied from the middle of the packer 6 to the reinforcing tube 1. After a partition is formed inside and outside the reinforcing tube 1 by discharging to some extent outside, the inside of the reinforcing tube 1 and the plurality of chambers partitioned by the packer 6 are injected by injecting a caking material from the injection hose 7. It is the structure which inject | pours and fills the consolidated material in the surrounding natural ground. In the figure, 10 is an exhaust hose.

  FIG. 11 (b) also shows a plurality of injection hoses 11a to 11c having different lengths in the reinforcing tube 1, and simultaneously injecting the caking material into the reinforcing tube 1 from the injection hoses 11a to 11c. In the reinforcing pipe and the surrounding natural ground, a solidification material is filled. Particularly, in the case of the figure, a static mixer 12 is provided at the outlet side end of each of the injection hoses 11a to 11c, and the inside of the reinforcing pipe 1 The urethane-based consolidated material is injected into the reinforcing tube 1 through the porous insert tube 13 provided over almost the entire length.

  By the way, the problem in the injection of the binder in the above-described ground reinforcement method is that if the seal on the mouth side of the reinforcing pipe 1, that is, the opening side of the drilled hole H is incomplete, the binder is It will flow out (leak) to the face side. Therefore, in FIGS. 11 (a) and 11 (b), the end of the reinforcing pipe 1 is closed by the cap 14 in FIG. 11 (a) and the caulking material 15 in the pipe in FIG. As a sealing means for the opening side end portion of the hole H, the mouth caulking material 16 is filled between the lower hole h and the reinforcing pipe 1 and is closed.

  Moreover, in the following Patent Document 2, in order to solve the above-mentioned problem, a predetermined length of the mouth portion of the reinforcing tube is configured with a porous tube, and first, by causing the consolidated material to actively leak from there. There has been proposed a method in which a bulkhead serving as a partition wall is formed in a natural ground around the mouth portion, and thereafter, injection is performed on the back side of the hole.

  However, in any of the above cases, when the reinforcing pipe is driven forward or obliquely forward from the peripheral edge of the tunnel face or the mirror surface, the guide cell of the drill jumbo J as shown in FIG. 8 and FIG. The reinforcing pipe 1 is supported by J1, and the hole H is formed in the horizontal direction or obliquely upward, and at the same time, the reinforcing pipe 1 is placed in the hole. Therefore, as shown in FIGS. 12B and 12C, the core of the lower hole and the core of the reinforcing pipe are displaced in such a direction that the lower end position of the reinforcing pipe is aligned with the lower end position of the lower hole, so that the drilling hole and the reinforcing pipe are provided. Will be made.

  For example, in the first receiving work A as shown in FIG. 8 and FIG. 12 (a), in the case where a reinforcing pipe is placed by drilling in an oblique direction, the built support work s is used as a guide to drill the hole. However, the reinforcing tube 1 as described above is extended by connecting several pipes having a diameter of about 100 mm and a length of about 3 m with a sleeve-like coupler 17 or the like. Since the center of the tube is aligned at the tip of the tube that is considerably long with respect to the diameter, the reinforcing tube is inevitably driven in a state where it is displaced to the lower inner peripheral surface side of the lower hole by its own weight.

  As a result, as shown in FIGS. 12B and 12C, the reinforcing pipe is shifted to the lower side of the lower hole, and it becomes difficult or impossible to pack a sealing material such as a caulking material around the reinforcing pipe. On the other hand, since the upper side of the reinforcing tube is wide open from the lower hole, it is easy to pack the sealing material, but it must be packed in a large amount. Therefore, the sealing work is complicated and troublesome, and it is not always possible to sufficiently seal. For example, in Patent Document 1, there is a risk that the consolidated material that has flowed in between the reinforcing tube and the drilling hole may leak. There is a risk of leakage of the caking material for forming the bulk head.

JP 2000-34882 A JP 2001-329779 A

  The present invention has been proposed in view of the above-described problems, and a solidified material is filled in the reinforcing pipe and the surrounding natural ground through a reinforcing pipe placed in the natural ground by a double pipe drilling method or the like. An object of the present invention is to provide a natural ground reinforcement construction method capable of easily and surely reinforcing a natural ground by preventing leakage of the above-mentioned consolidated material when reinforcing the natural ground and a bit for forming a pilot hole suitable therefor And

  In order to achieve the above object, the ground reinforcement method according to the present invention and the bit for forming a pilot hole used therefor have the following configurations. That is, the ground reinforcement method according to the present invention includes a first perforated portion having a diameter substantially equal to a diameter of a drilling hole for placing a reinforcing pipe, a diameter larger than the first perforated portion, and a concentric first. After forming a stepped pilot hole having two perforated portions in the ground, the first perforated portion is extended so that a hole having substantially the same diameter as that of the first perforated portion is formed, and at the same time in the bore After a reinforcing pipe is placed and a sealing means is interposed between the outer periphery of the rear end of the reinforcing pipe and the inner surface of the second perforated part, the reinforcing pipe is inserted into the reinforcing pipe and the surrounding natural ground via the reinforcing pipe. It is characterized by reinforcing the natural ground by filling the material with caking material. Further, the pilot hole forming bit according to the present invention is a pilot hole forming bit used in the above-described ground reinforcement method, and includes a first bit part for forming the first perforated part, and the second perforated part. The second bit portion for forming the portion is integrally and continuously provided concentrically.

  As described above, when the prepared hole is formed, the first prepared hole corresponding to the diameter of the reinforcing pipe to be placed is formed continuously with the normal prepared hole (second formed hole). When the stepped bit as described above is used as the working bit, the stepped pilot hole can be efficiently formed in one step. Moreover, the core of the lower hole and the core of the reinforcing tube were aligned by performing the double tube drilling hole and the reinforcing tube by inserting the reinforcing tube into the first perforated part formed as described above. Can be placed accurately in the form. In addition, the region where the sealing means in the second perforated portion of the prepared hole is to be interposed can be accurately formed in an annular shape around the reinforcing tube. As a result, the sealing work around the reinforcing pipe at the mouth portion can be made simple and reliable, and the sealing work is not troublesome. Further, it is possible to reliably prevent leakage from the mouth portion of the consolidated material to the face side.

  Hereinafter, the ground reinforcement method according to the present invention will be described in detail based on the embodiment shown in the drawings. FIG. 1 and FIG. 2 are process explanatory views showing an embodiment of a natural ground reinforcing method according to the present invention. First, as shown in FIG. A pilot hole h is formed. In the prepared hole forming bit b, in the illustrated example, as shown in FIGS. 1 (a) and 3, a first bit portion b1 for forming a first perforated portion h1 and a larger size than the first perforated portion h1. A second bit part b2 is provided which forms a second perforated part h2 which is concentric with the diameter.

  The diameter d1 of the first perforated part h1 and the first bit part b1 that forms the first perforated part h1 is formed to be substantially the same as or slightly larger than the diameter D of the reinforcing pipe 1 described later, and the reinforcing pipe 1 is driven. The diameter of the drilling hole H is approximately the same. In the drawing, b3 is a guide bit for drilling a guide hole h3 having a smaller diameter prior to the first bit portion b1, and b0 is an attachment base portion of the bit b. As shown in a), a drilling rod 18 or the like is connected by a joint 18a or the like, and the drilling rod 18 is rotated at a predetermined speed to prepare a pilot hole h having a first drilling portion h1 and a second punching portion h2. Is formed.

  After the pilot hole h having the concentric first perforated part h1 and the second perforated part h2 is formed as described above, the first perforated part h1 is extended as shown in FIG. Then, a drilling hole H having substantially the same diameter as the first drilled portion h1 is formed by the drilling bit 3 or the like as shown in FIG. 5C, whereby the drilled hole H is formed into the first drilled portion h1 and the second drilled portion h1. It can be accurately formed concentrically with the perforated part h2.

  In the present embodiment, the drill bit 3 is rotatably provided at the tip of the reinforcing tube 1 via the casing shoe 2 in the same manner as in the conventional example, and is formed by a drill rod 4 inserted into the reinforcing tube 1. The configuration is such that it is rotated via the bit adapter 5. The hole drilling hole 3 is drilled by a rotating motion accompanied by a hitting as required by the drilling bit 3, and at the same time the bit adapter 5, the drilling bit 3 and the casing shoe are inserted by the operation of inserting the drilling rod 4 into the drilling hole. The reinforcing tube 1 is driven through 2 in such a manner as to be drawn into the drilling hole.

  As the reinforcing pipe 1, for example, as shown in FIG. 4, a steel pipe having a large number of through holes 1a formed at a predetermined pitch on the peripheral surface (diameter) of about 100 mm, a high-strength vinyl chloride pipe, an FRP pipe, or the like Is used. Further, the reinforcing tube 1 and the drilling rod 4 are inserted into the drilling hole H while being sequentially added as necessary. In this case, the adding method is appropriate. For example, as shown in FIG. It can be added via a cylindrical coupler 17 or the like, or a male and female threaded portion can be formed at the end to be connected and screwed into each other, or an adhesive or welding can be used together.

  When the hole H having a predetermined depth is formed as described above, the reinforcing tube 1 having a predetermined length is sequentially placed in the hole H as shown in FIG. The bit adapter 5 and the drilling bit 3 are released from each other by reversing the rotation, and then the bit adapter 5 is pulled out and collected together with the drilling rod 4 from the reinforcing tube 1. Is left in the hole H. The drilling rod 4 and the bit adapter 5 drawn out and collected from the reinforcing tube 1 can be used repeatedly.

  The configuration of the drill bit 3 and the like is not limited to the above, and can be changed as appropriate. For example, a disposable bit such as a ring bit is attached to the tip of the reinforcing tube 1 and the disposable bit is attached to the tip of the drill rod 4. It may have a configuration in which a collecting bit such as an engaging center bit is mounted, or a so-called expanding bit that can be expanded to the same or slightly larger than the outer diameter of the reinforcing tube 1 at the time of drilling. At the time of drilling, the hole is projected forward from the tip of the reinforcing pipe, and the reinforcing pipe is placed while drilling. After the reinforcing pipe is placed, the expanding bit is reduced in diameter and collected. You may have done.

  In the illustrated example, the reinforcing tube is driven in such a manner that the reinforcing rod is pulled into the drilling hole in conjunction with the insertion operation of the drilling rod 4 into the drilling hole H. However, for example, it is independent of the insertion operation of the drilling rod 4. Alternatively, at the same time, the rear end portion of the reinforcing pipe may be pushed into the drilling hole or may be driven into the drilling hole H.

  Next, as shown in FIG. 1 (d), when the reinforcing tube 1 having a predetermined length is driven into the hole H, the mouth (opening) of the hole H is sealed with appropriate sealing means 20. In this embodiment, a donut-shaped packer 21 as shown in FIG. 2A is used as the sealing means 20. In the case of the figure, the packer 21 has a structure in which a water-expandable powder 22 that expands by reacting with water is accommodated in a hollow cylindrical elastic bag body 21a as shown in FIGS. In this embodiment, the water-swellable powder 22 is a mixture of a water-absorbing polymer 22a such as sodium polyacrylate and a water-curable solid material such as cement 22b. In the figure, reference numeral 23 denotes a water injection pipe for injecting water into the packer 21.

  The packer 21 is inserted between the second perforated part h2 and the reinforcing tube 1 as shown in FIG. 2 (b). In this case, for example, as shown in FIGS. 2 (a) and 5, the reinforcing tube 2 is inserted into the outer periphery of the end of the reinforcing tube 1 as shown in FIG. 2 (b) with the packer 21 fitted on the outer peripheral surface of the guide cylinder 24 having a diameter slightly larger than 1. FIG. If the guide cylinder 24 is pulled out and removed as in (), the packer 21 can be easily mounted on the outer peripheral surface of the reinforcing tube 1. In this case, if the bag body 21a of the packer 21 is formed of a stretchable material and the inner diameter of the packer 21 containing the water-expandable powder is smaller than the outer diameter of the reinforcing tube 1, the packer When 21 is fitted to the outer peripheral surface of the guide cylinder 24 or the reinforcing tube 1, the elastic bag body 21 a can be held in close contact with the outer peripheral surface of the guide cylinder 24 or the reinforcing tube 1.

  After mounting the packer 21 on the outer peripheral surface of the reinforcing pipe between the second perforated part h2 and the reinforcing pipe 1 as described above, water is injected into the packer 21 from the water injection pipe 23 as shown in FIG. Then, the water expandable powder 22 may be expanded. In the illustrated example, the water injected into the packer 21 is absorbed by the water absorbent polymer 22a of the water expandable powder 22 shown in FIG. The polymer 22a and the like expand from the state shown in FIG. As a result, as shown in FIG. 2D, both the inner and outer surfaces of the cylindrical packer 21 are brought into close contact with the outer peripheral surface of the rear end portion of the reinforcing tube 1 and the inner surface of the second perforated portion h2, and the reinforcing tube 1 and the lower hole h are formed. The gap is closed. Thereafter, in the embodiment, the water absorbed by the water-absorbing polymer 22a is gradually absorbed by the cement 22b in the packer 21 and gradually hardens by the hydration reaction of the cement, and the packer 21 expands and hardens. Kept in a state.

  Thereafter, as in the conventional example, the end of the reinforcing tube 1 on the mouth side is closed with a cap 14 as shown in FIG. 11 (a), an in-tube caulking material 15 as shown in FIG. 11 (b), and the like. What is necessary is just to reinforce by injecting and filling the solidified material into the reinforcing pipe 1 and the surrounding natural ground by the step injection method as shown in (a), the simultaneous injection method as shown in FIG.

  As described above, in the present invention, after forming the pilot hole h having the first perforated part h1 and the second perforated part h2 having a diameter larger than that of the first perforated part h1, the first perforated part h1 is extended. In this way, by providing the drilling hole H and simultaneously placing the reinforcing pipe 1 in the drilling hole H, a sealing means is provided between the outer peripheral surface of the rear end portion of the reinforcing pipe 1 and the second perforated part h2. Since the region to be interposed is formed in an accurate ring shape, the sealing means 20 can be interposed easily and reliably here.

  In particular, when the doughnut-shaped packer 21 containing the water-expandable powder 22 as in the above embodiment is interposed as the sealing means 20, there is a deviation or variation in the interval between the reinforcing tube 1 and the second perforated part h2. Since it is formed in an annular shape accurately, it is easy to load and can be easily and reliably sealed. Further, when the water-absorbing polymer 22a and the cement 22b are used as the water-expandable powder 22 as in the above-described embodiment, the water-absorbing polymer 22a expands when it absorbs water, and then hardens by the hydration reaction of the cement 22b. Thus, it can be stably and more reliably sealed.

  If the stretchable bag 21a of the packer 21 is made of a water-permeable material, the water-expandable powder 22 such as the water-absorbing polymer 22a in the packer is inflated by spring water that has permeated from the ground. The spring water can be temporarily stopped, and then the reinforcing tube mouth portion can be reliably sealed by hardening the cement 22b.

  As described above, the natural ground reinforcement method according to the present invention and the pilot hole forming bit used therefor have the above-described configuration, so that it is suitable for, for example, a so-called front receiving work or mirror part reinforcing work for reinforcing the natural ground in front of the face during tunnel excavation. In addition to the above, it can be effectively applied to ground reinforcement and other ground reinforcement methods.

(A)-(d) is process explanatory drawing to the reinforcement pipe | tube setting process which shows one Embodiment of the natural ground reinforcement construction method by this invention. (A)-(d) is process explanatory drawing of the mouth sealing process in the said embodiment. Explanatory drawing which shows an example of the bit for pilot hole formation. Explanatory drawing which shows an example of a reinforcing pipe and its connection coupler. The longitudinal cross-sectional view which shows an example of the packer as a sealing member. (A) And (b) is a perspective view of the packer before and after expansion. (A) And (b) is a schematic diagram of the water-expandable powder before and after expansion. The longitudinal cross-sectional view which shows an example of the conventional natural ground reinforcement construction method. The cross-sectional view of the conventional natural ground reinforcement method. (A)-(b) is process explanatory drawing to the reinforcement pipe | tube placing process in the conventional natural ground reinforcement construction method. (A) And (b) is explanatory drawing of the consolidation agent injection | pouring process in the conventional natural ground reinforcement construction method. (A) is explanatory drawing of the drilling state in the conventional natural ground reinforcement construction method, (b) is the one part enlarged view, (c) is the front view.

Explanation of symbols

A Preliminary work B Mirror part reinforcement G Ground mountain H Drilling hole f Cutting face g Consolidating material h Pilot hole
DESCRIPTION OF SYMBOLS 1 Reinforcement pipe 2 Casing shoe 3 Drilling bit 4 Drilling rod 5 Bit adapter 20 Sealing means 21 Packer 21a Stretchable bag 22 Water-expandable powder 22a Water-absorbing polymer 22b Cement 23 Injection pipe 24 Guide cylinder

Claims (5)

  A stepped pilot hole having a first perforated portion having a diameter substantially equal to a diameter of a drilling hole for placing the reinforcing pipe, and a second perforated portion having a diameter larger than that of the first perforated portion and concentric with the first perforated portion. After forming in the natural ground, the first perforated part is extended so as to extend a hole having substantially the same diameter as the first perforated part, and at the same time, a reinforcing pipe is placed in the drilled hole. After a sealing means is interposed between the outer periphery of the rear end portion and the inner surface of the second perforated portion, a solid material is filled by filling the reinforcing pipe and the surrounding natural ground via the reinforcing pipe. A natural ground reinforcement method characterized by reinforcement.   2. The natural ground reinforcement method according to claim 1, wherein the sealing means is a packer in which water-expandable powder that expands by reacting with water is contained in a hollow cylindrical bag.   The guide tube is inserted between the end portion of the lower hole side of the reinforcing tube and the inner surface of the second perforated portion in a state where the packer is fitted to the outer peripheral surface of the guide tube body having a larger diameter than the reinforcing tube. The ground reinforcement method according to claim 2, wherein the body is pulled out and removed.   The natural ground reinforcement method according to claim 2 or 3, wherein the stretchable bag is made of a water-permeable material.   2. A pilot hole forming bit for forming the stepped pilot hole according to claim 1, wherein the first bit part for forming the first punch part and the second punch part are formed. A bit for forming a pilot hole, characterized in that the second bit portion is provided continuously and concentrically integrally.

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