JP2002371790A - Lateral hole boring machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral hole boring machine making boring possible over a long distance in soil with compressive strength not higher than that of soft rocks. SOLUTION: The lateral hole boring machine performs boring by rotating a cutter head 3 provided at its front. The boring machine has on the outer periphery of the cutter head 3 cutter bits 29'-12 serving as leading boring means provided to protrude in jacking direction, and a plurality of cutter bits 29-11 to 29-1 disposed on the cutter head 3, from the cutter bits 29'-12 to radial positions of the cutter head 3 in such a way that they are located in sequence at the rear of the boring machine along the axis of the machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal hole excavator for excavating with a cutter head provided, for example, in front of a shield body, and more particularly, to a cutter bit provided at a plurality of radial positions of the cutter head. It relates to a horizontal hole excavator.

[0002]

2. Description of the Related Art A shield excavator, which is one of the horizontal hole excavators, usually has a plurality of bit mounting portions arranged in a circumferential direction of a cutter head provided in front of a shield body. In a so-called earth pressure shield excavator, the bit mounting portion is formed by a radially extending Katas spoke from a center frame at the tip of a center shaft, and each of the Katas spokes has a plurality of radial positions. The cutter bit is arranged in the. In a so-called muddy shield excavator, for example, on a substantially disk-shaped face plate, at a plurality of circumferential positions corresponding to the cut spokes, a bit mounting region extending radially from the center in the radial direction is provided to constitute the bit mounting portion. Each of these bit mounting areas also has a cutter bit at a plurality of radial positions. By rotating the cutter head having such a structure, the cutting face is excavated by the cutter bit.

[0003] The excavated earth and sand is agitated in the excavation chamber immediately behind the cutter head defined by the partition wall.
In the earth pressure type shield excavator, if necessary, mud material is injected to promote the plastic fluidization of excavated earth and sand, and the plastic fluidized earth and sand is discharged to the rear of the shield body by a soil discharging device such as a screw conveyor. I do. In the muddy shield machine, water is injected into the excavation chamber using a water injection means such as a water pipe, and the excavated earth and sand is discharged in a muddy state to the rear of the shield body by a mud draining means such as a mud drain pipe.

At this time, an erector is provided at the rear of the shield body, and the erector sequentially assembles the segment rings to construct a tunnel. Also, slightly ahead of the erector in the shield body, a plurality of shield jacks for giving propulsive force in the excavation direction to the shield body are arranged in a ring, and by extending these shield jacks and pressing the segment ring, The shield body is propelled forward, and the cutter head is pressed against the face. A backing material is injected into a hollow portion formed around the segment ring, and the hollow portion is filled.

[0005] In this manner, the front face is excavated and excavated while the shield body is propelled, and a tunnel is constructed on the rear side by a segment ring. In the shield method, a tunnel is formed in a predetermined underground section from one excavated shaft (starting shaft) to another shaft (reaching shaft) by repeating the above operation using a shield excavator. Things. By the way, in general, the soil (stratum) of the ground to be excavated by the shield machine is:
From hard to soft, there are, for example, rock, consolidated silt, clay, sandstone, cobblestone, sand, cohesive soil (silt, clay), and the like. Normally, compressive strength 500kgf / c
hard rock things than compressive strength it larger the m ² degree as a boundary,
Small ones are called soft rocks. When excavating with a shield machine, the soil other than hard rock (in other words, the soil with a compressive strength equal to or lower than soft rock, hereinafter simply referred to as “soil below soft rock” as appropriate) is used as a tip as a cutting edge (carbide tip).
Can be excavated with a normal cutter bit attached to the tip of the bit body, but when excavating hard rock, it is difficult to excavate with this normal cutter bit. In many cases, a roller bit rotatably supporting a cutting roller for cutting a face is used for a shaft connected to the shaft.

In the case of excavating a hard rock which has relatively high compressive strength and is difficult to excavate among the hard rocks, for example, as described in JP-A-2000-64788,
In a shield machine in which roller bits are arranged at a plurality of radial positions of a cutter head provided in front of a shield body and excavation is performed by rotating the cutter head, a roller bit located at a radially most central side of the cutter head is provided. , Projecting to the front in the digging direction, and arranging the roller bits at other adjacent radial positions to be sequentially retracted to the rear in the digging direction to form a digging surface such that the vertical cross-sectional shape becomes substantially step-shaped. An excavator has been proposed.

In this shield machine, excavation is performed while maintaining the vertical cross-sectional shape of the ground excavation surface in a substantially stepped shape (so-called undercutting), so that the substantially stepped edge portion (during excavation) is formed. Inducing exfoliation and crushing in the back edge of the excavation direction), thereby reducing the excavation force (pressure) required for excavation and enabling excavation of high compression strength soil with less excavation force than before. Things.

[0008]

In general, in a shield excavator, the cutter bit is worn by sliding with a face as the excavation work progresses. There are limitations. Conventionally, a shield excavator has a relatively short excavation distance, and a relatively short section (for example, 1 km) from one shaft (starting shaft) to another shaft (reaching shaft) is excavated by one shield excavator. After that, the relatively short section from the other shaft to the further shaft (the same) had to be excavated using another shield machine or after replacing worn cutter bits.

[0009] In recent years, it has become difficult to install a large number of starting and reaching shafts based on the background of the progress of urbanization and the like, and further reduction in the cost of excavating and installing shafts and the cost of manufacturing shield machine is desired. As a result, there is a growing need to increase the excavation distance by one shield excavator as much as possible.

[0010] The inventors of the present application have proposed that the same vertical cross-sectional shape as that of the above-mentioned prior art is substantially stepped, using the normal cutter bit, for the soil of the soft rock or lower which is relatively widely distributed in the stratum of Japan. By newly excavating, it was newly found that long-distance excavation is possible without using a heavy equipment structure such as the roller bit.

An object of the present invention is to provide a horizontal hole excavator which enables excavation over a long distance in soil having a compressive strength of soft rock or less.

[0012]

(1) In order to achieve the above object, the present invention relates to a horizontal hole excavator for excavating by rotating a cutter head provided at a front portion thereof. A first excavating means provided so as to protrude in the propulsion direction, and the cutter head so as to be sequentially located at a radial position of the cutter head from the preceding excavating means and at an axially rear side of the horizontal hole excavator. And a plurality of cutter bits arranged in the same manner.

In the present invention, the leading digging means is made to protrude in the digging direction at the outer peripheral portion of the cutter head, and a plurality of cutter bits are sequentially positioned radially from the leading digging means and rearward in the axial direction. To be installed in Thus, excavation can be performed (so-called undercutting) while forming an excavation surface such that the vertical cross-sectional shape becomes substantially stepwise from the excavation surface excavated by the advance excavation means. That is, the plurality of cutter bits generate cracks at the root side of the substantially stepped edge (corner) by the pressing force and cause the crack to propagate, and continuously perform oblique shear failure on most of the edge. Excavation is carried out by performing induced delamination and crushing. Therefore, the excavation force required at the time of excavation can be reduced, and the excavation of the ground can be performed with a small excavation force as compared with normal excavation. Thereby, the wear of the cutter bit caused by sliding with the cutting face can be reduced, and the excavation distance can be improved. Also, rather than excavating the ground face with the cutting edge of the cutter bit as in ordinary excavation, excavation is performed mainly by peeling and crushing as described above, so the cutting edge of the cutter bit is worn and sharpened. Excavation capacity can be secured. Therefore, the excavation distance can be improved also by this. As described above, the excavation distance can be greatly improved as compared with normal excavation, so that a sufficiently long excavation can be performed on soil having a compressive strength of soft rock or less.

Further, when undercutting is performed from the preceding excavation surface on the outer peripheral portion of the cutter head as described above, for example, when the preceding excavation means is provided at the radially central portion of the cutter head, the cutting face to be excavated is cut. Since the shape is a shape in which a concave surface (substantially mortar shape) is laid down, if it is assumed that the face collapses, the upper portion of the concave shape will collapse. On the other hand, in the present invention, the leading excavation means is provided on the radially outer peripheral portion of the cutter head, and the shape of the excavated face is a shape in which a convex surface (substantially conical shape) is laid down. When a mountain collapse occurs, the lower portion of the convex shape collapses, and the amount of collapsed soil can be reduced to a smaller amount than in the above-described case. Therefore, it is possible to reduce the possibility of occurrence of ground surface depression or the like due to the collapse of the ground.

At this time, the influence on the ground surface is less likely to occur as the earth covering becomes thicker. However, when the above-mentioned preceding excavating means is provided at the center in the radial direction and the shape of the face becomes concave, the usual lateral hole excavation is performed. Similarly to the excavator, the thickness from the upper end to the ground surface in the outer peripheral portion of the excavator is the earth covering thickness, whereas in the present invention, the leading excavation means is provided on the outer peripheral portion, and the face shape is, for example, the central portion in the radial direction projects Therefore, the thickness from the height of the central axis of the convex surface to the ground surface can be considered as the actual overburden thickness. Therefore, since the thickness of the overburden can be further increased, it is possible to further reduce the possibility of the occurrence of the collapse of the ground surface due to the collapse of the ground.

(2) In order to achieve the above object, the present invention relates to a horizontal hole excavator for performing excavation by rotating a cutter head provided at a front part thereof. A protruding excavating means provided so as to protrude, and from the preceding excavating means, a radial position of the cutter head and an axially rearward side of the horizontal hole excavator sequentially positioned from the preceding excavating surface excavated by the preceding excavating means. And a plurality of cutter bits disposed on the cutter head so as to exfoliate and crush sequentially.

(3) In the above (1) or (2), preferably, in addition to the preceding digging means provided on the outer peripheral portion of the cutter head, another preceding digging means is provided on the cutter head.

(4) In the above (3), more preferably, the other preceding excavating means is provided at a central portion of the cutter head.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing the entire structure of an embodiment of a horizontal hole excavator according to the present invention.
FIG. 2 is a front view as viewed in the direction of arrow A in FIG. 1.

In FIGS. 1 and 2, the horizontal hole excavator according to the present embodiment is a so-called shield excavator, for example, soft rock, consolidated silt, dotan, cobblestone-sand, gravel,
It is particularly suitable for excavation of soft soils such as sand and cohesive soil (silt, clay) and the like (in other words, soils other than hard rocks). For this reason, a shield body 1 having a structure in which a front body 1A located at the forefront in the excavation direction and a rear body 1B adjacent to the rear side thereof are connected in a bendable manner, and the inside of the shield body 1 and the excavation room P 2, a cutter head 3 provided on the front side (left side in FIG. 1) of the front body 1A in the excavation direction, excavating the ground face M and taking it into the excavation chamber P (described later); A cutter driving device (for example, an electric motor or a hydraulic motor) 4 that rotationally drives the head 3, and a so-called peripheral support type rotation that is attached to the partition wall 2 and transmits a driving force from the cutter driving device 4 to the cutter head 3. Transmitter 5 and, dumping device for discharging and conveying the excavated earth and sand taken into the excavation chamber P in the excavation direction rear side of the shield body 1, for example a screw conveyor 6
And a tunnel (not shown) provided in the rear trunk 1B.
And an erector device 9 for sequentially assembling the segment rings S for lining the inner surface of the device.

The rotation transmission mechanism 5 includes a cutter head 3
Four cutter arms 35 respectively connected to radial outer peripheral portions of the cut spokes 27A to 27D (details will be described later).
And a substantially annular cutter ring 34 disposed through the partition 2 and a bearing 33 having an inner ring 33a fixed to the cutter ring 34. A gear 32 is provided on the inner ring 33a of the bearing 33, and the pinion 31 attached to the cutter driving device 4 is provided.
Are engaged. These cutter driving devices 4 are fixed to the mounting portion 2a provided on the partition 2 together with the outer ring 33b of the bearing 33. Although not shown, they are annularly arranged at equal intervals.

Between the front body 1A and the rear body 1B, there is provided a center-bending mechanism 11 for slidably connecting the front body 1A and the rear body 1B. That is, a sliding portion 11a whose outer peripheral surface is substantially spherical is provided at the front end of the rear trunk 1B, and the rear end of the front trunk 1A is in sliding contact with the sliding portion 11a. 1
A substantially ring-shaped seal member 11b for sealing (preventing intrusion of earth and sand, groundwater) between the sliding portion 11a and the rear end of the front body 1A is provided.
b constitutes the center bending mechanism 11.

At this time, the center bending jack bracket 12 provided inside the front body 1A and the ring girder 13 provided at the foremost part of the rear body 1B (in detail, on the inner peripheral side of the sliding portion 11a). A plurality (for example, eight) of middle folding jacks (front trunk propulsion jacks) 14 are provided in the circumferential direction between the folding jack bracket 13a. And
At the time of constructing a curve or correcting the direction of excavation, the extension and contraction operation of the middle folding jack 14 causes the middle folding mechanism 11 to move.
The front trunk 1A is bent with respect to the rear trunk 1B through the through hole, and the angle formed by them can be changed to change the excavation direction.

Further, a shield jack bracket 13b is provided at a circumferential position of the ring girder 13 provided on the rear trunk 1B, which is different from that of the center bending jack bracket 13a.
A plurality (for example, 10) of shield jacks 15 are attached in the circumferential direction to b.

These shield jacks 15
Although not particularly shown in detail, they are arranged, for example, at equal intervals in a ring shape, and are extended to form a shield jack 15.
By pressing the spreader 16 connected to the rear end portion 15a in the excavation direction against the existing segment ring S, the pressing reaction force is applied to the cutter head 3 via the front body 1A as propulsion force forward in the excavation direction. This allows
During the excavation, the cutter head 3 is pressed against the face of the ground.

The screw conveyor 6 has a suction port 6d opened at the lower part of the excavating chamber P, and a casing 6a for forming an earth removal path for excavated earth and sand inside the casing 6a. And a driving device for rotating the screw shaft 6b, for example, a hydraulic motor 6c. The screw shaft 6b is rotated by the driving force of the hydraulic motor 6c, and is provided below the excavation chamber P. Suction port 6
d is taken in and discharged to the rear inside the shield main body 1.

A tail seal portion 8 having a plurality of tail packings 8a is provided at the rear end of the rear trunk 1B, whereby the rear end of the shield body 1 of the shield excavator moving forward. A seal is formed between the section and the segment ring S to prevent intrusion of water and earth and sand from outside the shield machine into the machine.

The above-mentioned erector device 9 is provided with an erector ring 18 which is guided by a guide roller 10 arranged along the inner periphery of the rear trunk 1B and is driven to turn by a turning motor (not shown). The segments (not shown) constituting the divided pieces of the segment ring S are lifted one by one, transported to a predetermined assembly position, and the existing segment rings S adjacent to the shield body 1 in the axial direction (the front-rear direction of excavation) and The segment ring S is assembled by sequentially fastening bolts to the existing segments adjacent in the circumferential direction.

(1A) Structural features of the shield machine according to the present embodiment The most significant structural features of the shield machine according to the present embodiment are the shape of the cutter spoke in the cutter head 3 and the arrangement of the cutter bits. Hereinafter, this will be described.

In FIG. 2 described above, the cutter head 3 extends radially from the center in the radial direction toward the outer peripheral side in the radial direction.
A plurality (four in this example) of cut-spokes 27A, 27B, 27C, 2 extending back to the middle right)
7D (see FIG. 2) and these cut-spoke pork 27A-2
An annular member 27E provided so as to sequentially connect the outermost peripheral portions of 7D in the circumferential direction. At this time, the outer diameter dimension of the cut spokes 27A to 27D (in other words, the outer diameter dimension of the annular member 27E) is substantially equal to the inner diameter dimension of the circular section to be excavated.

The cutter bits 29'-1 and 29- are provided on the cutter spokes 27A to 27D and the annular member 27E from the inner peripheral side to the outer peripheral side so as to be at a plurality of radial positions in the cutter head 3. 2,29-3,29-
4,29-5,29-6,29-7,29-8,29-
9, 29-10, 29-11, 29'-12 are arranged in this order. That is, the cutter bits 29-5 and 29-9 are arranged in this order from the inner circumferential side to the outer circumferential side in the cut-spoke 27A, and the cutter bits 29B are arranged from the inner circumferential side to the outer circumferential side in the cut-spoke 27B. The cutter bits 29-3, 29-7, and 29-11 are arranged in this order, and the cutter bits 29-4, 29- are arranged on the cutter spoke 27C and the annular member 27E from the inner peripheral side toward the outer peripheral side. 8, 29'-12 are arranged in this order, and the cutter bits 29-2, 29-6, 29 are provided on the cut spokes 27D from the inner peripheral side toward the outer peripheral side.
-10 are arranged in this order,
At the center 27F where 7A-D intersect, a cutter bit 2
9-1 are arranged, and four cutter bits 29'-12 are arranged on the annular member 27E. In addition,
The reason why five cutter bits 29'-12 on the outer peripheral side are provided is that the cutter bits 29'-12 are provided with other cutter bits 29-1 to 29-1 for excavation by peeling and crushing described later.
This is because normal excavation is performed prior to No. 1 and the excavation burden is the largest. In addition, if it becomes difficult to excavate the outermost peripheral position, the propulsion itself of the shield body 1 in the excavation direction cannot be performed. Therefore, the excavation load per cutter bit 29'-12 at this position is reduced. There is also the significance of making every effort to ensure the drilling capacity.

At this time, each of the cutter bits 29-1 to 29-2
As shown in FIG. 2, the positions of the 9'-12's are slightly shifted from each other in the radial direction, and the entire cutter bits 29-1 to 29'-12 at the 12 radial positions are radially centered. From the side to the radially outer side, so that when the cutter head 3 rotates, the outer diameter is substantially equal to the annular member 27E by the cutter bits 29-1 to 29'-12 (strictly, slightly larger). , See the two-dot chain line in FIG. 2) A circular cross section can be excavated.

The cutter bits 29-1 and 29-2
As shown in Fig. 1, the 9'-12 excavation direction arrangement is such that the cutter bit 29'-12 located at the radially outer peripheral portion (located at the radially outermost peripheral side) projects to the foremost forward direction in the excavation direction. , The radial position of the cutter bit 29'-1
Cutter bit 2 sequentially adjacent to the inner peripheral side at the radial position 2
, 29-2, 29-1 so that the cutting edges (approximately vertical blade surface portions 29Aa to be described later) are sequentially retracted rearward in the excavation direction.
7D. Then, by this, the excavation direction excavation surface Ma (see FIG. 9 described later) and the radial excavation surface Mr
Excavation surface M having (same as above) and having a substantially step-like vertical cross section
(Same as above).

FIG. 3 shows cutter bits 29-1 to 29'-.
12 showing the detailed structure of the cutter bits 29-1 to 29-11 excluding the outermost cutter bit 29'-12 of FIG.
FIG. 4 is a top view as viewed from a direction B in FIG. 3, and FIG. 5 is a side view as viewed from a direction C in FIG. In these figures, the excavation direction excavation surface Ma and the radial direction excavation surface Mr provided on the substantially stepped excavation surface M are also shown for easy understanding of the mounting direction at the time of excavation. .

In FIGS. 3, 4, and 5, the cutter bits 29-1 to 29-11 have the same structure, and include a bit body 29B and a cutting blade provided so as to be embedded in the bit body 29B. Carbide tip 2 as
9A.

The cemented carbide tip 29A is provided with a digging surface Ma in the digging direction.
A substantially vertical blade surface portion 29Aa which is substantially parallel to the inner surface of the cutter head 3, an inclined blade surface portion 29Ab provided on the inner peripheral side of the cutter head 3 and having a predetermined inclination angle θa with respect to the excavation direction excavation surface Ma, and a radial direction excavation surface Mr. A substantially horizontal blade surface portion 29Ac that is substantially parallel to the
And an inclined blade surface portion 29Ad provided on the rear side in the excavation direction and forming a predetermined inclination angle θr with respect to the radially excavated surface Mr.

With the above structure, the cutter bit 2
9 has a negative rake angle γa with respect to the digging surface Ma as shown in FIG. 4, and also has a negative rake angle γr with respect to the radial digging surface Mr as shown in FIG. .

FIG. 6 shows the outermost cutter bit 29'-1.
2 is a partially enlarged view showing a detailed structure of FIG. 2 and FIG.
FIG. 8 is a top view seen from the direction D in FIG. 6, and FIG.
It is the side view seen from the direction. In these figures, as in FIGS. 3 to 5, the digging surface Ma and the radial digging surface Mr (two in this case) are also shown.

In FIGS. 6, 7 and 8, all the cutter bits 29'-12 have the same structure. It has a shape like two joined,
Bit body 29'B and carbide tip 2 as an excavating blade provided to be embedded in bit body 29'B
9'A (this carbide tip 29'A is thicker than the carbide tip 29A).

The cemented carbide tip 29'A is provided with a digging surface M
A substantially vertical blade surface portion 29'Aa1, 29 'substantially parallel to a
Aa2, the inclined blade surface portions 29'Ab1, 29'Ab2 provided on the inner peripheral side of the cutter head 3 and forming a predetermined inclination angle θa with the excavation surface Ma in the excavation direction, and substantially parallel to the radial excavation surface Mr. Basic horizontal blade surface 29'Ac1, 29'Ac2
The inclined blade surface portion 29′Ad1, which is provided on the rear side in the excavation direction and forms a predetermined inclination angle θr with respect to the radially excavated surface Mr,
29'Ad2. It should be noted that the horizontal blade surface portion 29'Aa at the lower portion in FIG. 8 corresponds to the one newly added functionally as compared with the other cutter bits 29-1 to 29-11.
2, 29 'Ab2, 29' Ac2, 29 'Ad2
These cutter bits 29'-12 correspond to the preceding excavation, and are mainly excavation when correcting the direction of the excavation direction or when constructing a curve. That is, in the case of such excavation, excavation in the radial direction inside or outside is required together with front excavation.

With the above structure, the cutter bit 2
9′-12 has a negative rake angle γa with respect to the digging surface Ma in the excavation direction as shown in FIG. 7 and a negative rake angle γr with respect to the radial digging surface Mr as shown in FIG. Have. In the above, the cutter bits 29'-12
Constitutes a preceding excavation means provided so as to protrude in the propulsion direction described in each claim.

(1B) Basic Operation of Shield Machine The basic operation of the shield machine of the present embodiment configured as described above will be described below. The shield machine rotates the cutter head 3 with the driving force of the cutter driving device 4,
Cutter bits 29A to 27D of cutter head 3 and cutter bits 29-1 to 29-2 provided on annular member 27E.
The ground is excavated by 9'-12. At this time, the propulsive force to the cutter head 3 is given by extending the shield jack 15 with the existing segment ring S as a reaction force receiver as described above.

The excavated earth and sand is stirred and plastically fluidized in the excavation chamber P by the cutter spokes 27A to 27D of the cutter head 3, thereby preventing the collapse of the ground and stopping water. At this time, if necessary, a mud material for promoting plastic fluidization of excavated earth and sand is injected from a mud material injection pipe 28 (see FIG. 1) provided on the outermost peripheral side of the cutter head 3. . The plasticized fluidized sand is taken into the screw conveyor 6 and discharged.

After digging for a predetermined distance (for example, a distance of one stroke of the shield jack 15) in this way, the shield jack 15 is contracted, and the space created between the spreader 16 and the existing segment ring S is reduced. ,
A new segment ring S is assembled and arranged by the erector device 9 and bolted to the existing segment ring S. At this time, a backing material is injected into a hollow portion formed around the segment ring S by, for example, an injection means (not shown), thereby filling the hollow portion.

Then, the newly arranged segment ring S is again used as a reaction force, the shield jack 15 is extended, the shield body 1 is propelled forward, and the cutter head 3 is rotated to excavate the ground again. To go.

The above procedure is repeated to construct a tunnel having a circular cross section. The earth and sand around the segment ring S after the shield machine has passed is injected and filled with, for example, an age hardening backfill material by an injection means (not shown).
Fix the tunnel wall to the ground.

(1C) Detailed Excavation Operation and Action of Cutter Head The greatest feature of the operation of the shield excavator according to the present embodiment is that the radial position of the cutter head 3 on the outer peripheral side is most protruded forward in the excavation direction. From the cutter bits 29-12'28 as the excavation means, the cutter bits 29-11, 29-10,.
By arranging the cutting edges 9-2 and 29-1 so as to retreat one by one to the rear in the excavation direction, excavation is performed while maintaining the vertical cross-sectional shape of the excavated surface M of the ground in a substantially stepped shape (so-called). Undercutting).

FIG. 9 is an explanatory diagram showing a state in which this undercutting is being performed. Of the above-mentioned cutter bits 29-1 to 29'-12, the cutter bit 29-7 in FIG. The portion F is extracted and enlarged by taking a portion F representing the portion as an example. In the shield machine according to the present embodiment, the five cutter bits 2 that precede the machine direction
9'-12, a substantially conical leading excavation surface is formed on the face, and the leading excavation surface is used as a foothold for each cutter bit 2.
9-11 to 29-1 excavate sequentially. As a result, as illustrated in FIG. 9 on the outer peripheral side of the preceding excavation surface, the vertical cross-sectional shape is substantially a step-like shape including the excavation direction excavation surface Ma and the radial direction excavation surface Mr over most of the excavation surface M of the ground. An excavation surface is formed (at this time, each cutter bit 29'-12 to 29-
A surface Cc connecting the positions of the tip end portions of the first blade is a conical surface (represented by a straight line in FIG. 9). With such an excavation mode, a crack is generated at the root side of the substantially stepped edge (corner) Mc by the pressing force of the cutter bits 29-1 to 29-11 in the excavation direction (left direction in FIG. 9). Cr is generated and propagated, and most of the edge Mc (portion shaded in FIG. 9)
Peeling and crushing that continuously induces shear failure in an oblique direction can be performed. This makes it possible to reduce the excavation force required for excavation, so that excavation of the ground can be performed with a smaller excavation force than in ordinary excavation.

(1D) Effects of the Shield Machine of the Present Embodiment The effects obtained by the shield machine of the present embodiment having the above-described configuration and operation will be sequentially described below.

(1D-1) Effect of improving excavation distance by peeling and crushing As described in the above (1C), in the shield excavator of the present embodiment, mainly the cutter bits 29-1 to 29-1.
Excavation by exfoliation and crushing in 1 makes it possible to reduce the excavation force required for excavation, and it is possible to excavate the ground with a small excavation force as compared with normal excavation. Therefore, the wear of the cutter bits 29-1 to 29-11 due to sliding with the ground face (excavation surface M) can be reduced accordingly (especially for soft rock, earthen stone, cobblestone, gravel, sand, etc.). Effective), the excavation distance can be improved. In addition, instead of excavating the ground face with the cutting edge of the cutter bit as in ordinary excavation, excavation is mainly performed by peeling and crushing as described above, so that the cutter bits 29-1 to 29- Even when the cutting edge of the eleventh blade is worn and no longer sharp, a relatively large excavating ability (efficiency) can be secured. Therefore, the excavation distance can be improved also by this. As described above, the excavation distance can be greatly improved as compared with normal excavation, so that a sufficiently long excavation (for example, 2 km or more) can be performed on soil having a compressive strength of soft rock or less.

(1D-2) Reduction Effect of Cutter Driving Torque by Peeling and Crushing Excavation by peeling and crushing is more efficient than ordinary digging by cutting the ground face with the cutting edge of a cutter bit. (The ratio of the excavation amount) is greatly improved, so that the same excavation as before can be performed with a small driving torque. That is, energy saving can be achieved, and the load on the cutter driving device 4 for rotatingly driving the cutter head 3 can be reduced, and the life thereof can be improved.

(1D-3) Further Improvement Effect of Excavation Distance by Inclination Angle θa to Excavation Surface Ma As described in (1D-1), in the shield excavator of the present embodiment, the cutter bit 29 is excavated during excavation. -1 to 2
A large part of the excavation surface edge (corner) Mc is obliquely shear-ruptured by the pressing force of 9-11 to perform peeling and crushing. At this time, the carbide tips 2 of the cutter bits 29-1 to 29-11 are used.
While the substantially vertical blade surface portion 29Aa of 9A is arranged almost parallel to the excavation surface Ma in the excavation direction, the inclined blade surface portion 29Ab is obliquely arranged so as to form a predetermined inclination angle θa with the excavation surface Ma in the excavation direction. I have. Thereby, as the vehicle advances in the excavation direction, a pressing force is applied to the edge Mc in a direction (in this case, toward the radially outer peripheral side) in such a direction as to promote shear failure as indicated by a thick arrow in FIG. It becomes possible. This makes it possible to excavate the ground with a smaller excavating force, thereby reducing the wear of the cutter bits 29-1 to 29-11 and further improving the excavation distance.

(1D-4) Effect of Negative Rake Angle γa on Excavation Surface Ma in Excavation Direction The shield excavator of the present embodiment performs excavation by peeling and crushing as described in (1D-1). It is not necessary to provide a positive rake angle with respect to the excavation surface Ma in the excavation direction. Therefore, as described above, in the present embodiment,
Each of the cutter bits 29-1 to 29-10 has a negative rake angle γa with respect to the excavation surface Ma in the excavation direction (see FIG. 4). Thus, both the forward-direction excavation cutter bit and the reverse-direction excavation cutter bit are arranged corresponding to the forward / reverse bidirectional rotation of the cutter head like a normal excavation cutter bit having a positive rake angle. As shown in FIG. 2, one cutter bit 2 is provided on each of the cutter spokes 27A to 27D at each circumferential position of the cutter bit 3.
It is possible to cope with the rotation of the cutter head 3 in any direction only by providing the 9-1 to 29-11 (the five cutter bits 29'-12 have the same shape, and each has the same shape. Supports rotation in any direction). As a result, the number of cutter bits can be significantly reduced as compared with the conventional structure, so that the sliding resistance with the ground face (excavation surface M) can be reduced, and the cutter head driving torque can be further reduced.

When both the cutter bit for forward rotation and the cutter bit for reverse rotation are arranged to have a positive rake angle as in the conventional structure described above, excavated earth and sand adhere between the cutter bits on both sides thereof. By doing so, the cutter head driving torque may be increased in some cases, but such a phenomenon can be prevented beforehand (in particular, it is effective for soil, clay, etc.).

As described above, since the cutter head driving torque can be further reduced, the load on the cutter driving device 4 can be further reduced.

Further, the number of cutter bits can be reduced by reducing the number of cutter bits as compared with the conventional structure, or the number of cutter bits can be increased, for example, twice without increasing the cost.

(1D-5) Effect in Side Drilling The cutter bits 29-1 to 29-11 of the present embodiment are as follows.
An inclined blade surface portion 29Ad that forms a predetermined inclined angle θr with respect to the radial excavation surface Mr is provided (see FIG. 5). This allows
When performing digging (so-called side digging) in a direction (radial direction) perpendicular to the digging direction, the above-mentioned (1D-
As in 3), the edge M
Since it is possible to apply a pressing force to c so as to promote shear failure, it becomes possible to dig the ground with a small excavation force.

(1D-6) Effect of Preliminarily Excavating the Outer Peripheral Side This effect will be described with reference to a comparative example. In the case where undercutting is performed from the preceding excavation surface on the outer periphery of the cutter head as described above, for example, as a comparative example, a case where the preceding excavation means is provided at the radial center of the cutter head is imagined. As shown in FIG. 10A, the shape of the face to be excavated is a shape in which a concave surface (substantially mortar shape) is laid down. For this reason, if it is assumed that ground collapse of the face will occur, the upper part of the concave shape (FIG. 1)
0 (a), the portion indicated by the arrow a) collapses (see the thick arrow).

On the other hand, in the present invention, the cutter bit 29'-12, which is the preceding excavation means, is connected to the cutter head 3
As shown in FIG. 10 (b), the face to be excavated has a convex surface (substantially conical shape). For this reason, when the ground collapse of the face occurs, the lower portion of the convex shape (FIG. 10B)
The part indicated by the middle arrow A) will collapse. Therefore, as apparent from comparison with FIG. 10A, the amount of collapsed soil can be reduced as compared with the above comparative example. Therefore, it is possible to reduce the possibility of occurrence of ground surface depression or the like due to the collapse of the ground.

In general, the influence on the ground surface of a horizontal hole excavator is less likely to occur as the soil cover becomes thicker. However, in the comparative example, as in the case of a normal horizontal hole excavator, the influence on the ground surface is reduced. While the thickness to (from FIG. 10 (a)) from the upper end to the ground surface is the soil cover thickness, in the present invention, a cutter bit 29'-12, which is a preceding excavation means, is provided on the outer peripheral portion and the face shape is Since the radial center part is a protruding convex surface, the thickness t from the height of the central axis of the convex surface to the ground surface (FIG. 10)
(See (b)) can be considered as the actual earth cover thickness. Therefore, since the thickness of the overburden can be further increased, it is possible to further reduce the possibility of the occurrence of the collapse of the ground surface due to the collapse of the ground.

(ID-7) Enhancement of Excavation Force in Preceding Excavation In general, in a shield excavator, as the excavation work progresses, the cutter bit is worn by sliding with the face. Here, in the cutter head 3 according to an embodiment of the shield machine of the present invention, a substantially annular preceding excavation surface is formed on the face by the cutter bit 29′-12 preceding in the excavation direction, and the preceding excavation is performed. The cutter bits 29-11 to 29-1 sequentially perform excavation using peeling and crushing using the surface as a foothold. That is, cutter bit 2
9'-12 are the cutter bits 2 which are sequentially adjacent in the radial direction.
Since the starting point excavation which is a foothold for performing the separation and crushing of 9-11 to 29-1 is performed, the excavation burden is particularly larger than the other cutter bits 29-11 to 29-1.
For this reason, the cutter bit 29'-12 may wear out faster than the other cutter bits 29-1 to 29-11 as it is, and as a result, the improvement of the excavation distance may be insufficient.

Therefore, in the present embodiment, as described above, for the cutter bits 29'-12 on the radially outermost side, the thickness of the cemented carbide tip of the cemented carbide tip 29'A is determined by the cutter bits 29-1 to 29-1A. The thickness is made thicker than the carbide tip 29A of 29-11, and furthermore, multiple (five in this case) are arranged at positions where the excavation trajectory is substantially on the same circumference. As a result, the outer peripheral part in the radial direction (the leading excavation part) where the excavation load is greatest
And the wear resistance of the cutter bit 29'-12 is improved as compared with the other cutter bits 29-1 to 29-11. As a result, the service life of the cutter bit 29'-12 itself is improved, and the durability is improved. As a result, the excavation distance of the shield body 1 can be improved. Also, 1
Even if one bit is lost, it can be covered by the other bit, so that there is an effect that the reliability of the excavation performance can be ensured.

(ID-8) Effect of Arrangement of Sludge Injection Pipe In a normal shield excavator of this type, the sludge injection port is
It is provided at the radial center. In the present embodiment, in the case where the sludge material injection port is provided at the center in the radial direction (for example, in the vicinity of the cutter bit 29-1), the other cutter bits 29-2 to 29-11 on the outer peripheral side due to the structure. , 29'-
It is difficult for the mud material to wrap around 12 and there is a possibility that the mud material is not mixed into the excavated earth and sand particularly on the outer peripheral side. Therefore, in the present embodiment, the sludge material injection pipe 28 is provided on the outermost peripheral side in the radial direction, and the sludge material is injected from the pipe 28, so that the sludge material is spread evenly in all areas in the radial direction. It is possible to reliably mix the mud material.

In the embodiment of the present invention, the inclined blade surface portion 29Ab of the carbide tip 29A of each of the cutter bits 29-1 to 29-11 has a predetermined inclination angle θa with respect to the excavation surface Ma in the excavation direction. And the cutter bits 29-1 to 29-10 have a negative rake angle γa with respect to the excavation surface Ma in the excavation direction, but it is not always necessary to provide these structures. That is, the entire cutting direction side of the carbide tip 29A of the cutter bits 29-1 to 29-11 is set as a substantially vertical blade surface portion 29Aa, and the entire surface in the cutting direction is arranged substantially parallel to the cutting direction cutting surface Ma. The cutter bits 29-1 to 29-11 may have a positive rake angle with respect to the excavation surface Ma in the excavation direction. Also in this case, the effect of improving the excavation distance and the effect of reducing the cutter driving torque by performing peeling and crushing can be obtained.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 11 is a side sectional view showing the overall structure of another embodiment of the horizontal hole excavator (shield excavator) of the present invention. Parts equivalent to the above-described embodiment of the present invention include:
The same reference numerals are given and the description will be appropriately omitted.

In FIG. 11, the shield machine according to the present embodiment is configured such that the cutter bit 29'-12 at the outer peripheral portion in the radial direction protrudes to the forefront in the excavation direction as in the embodiment of the present invention. Cutter bit 2 sequentially adjacent to the inner circumference
In addition to the first-stage excavation section 60 for sequentially retreating the cutting edge 9 (details will be described later) backward in the excavation direction, the cutter bit 29-1 at the radially central portion (central portion) of the cutter head 3 is moved forward in the excavation direction. And a second-stage excavation part 70 in which the cutting edge of the cutter bit 29 (details will be described later) adjacent to the radially outer peripheral side is sequentially retracted rearward in the excavation direction.

That is, the first-stage excavation section 60 has the same structure as that of the embodiment of the present invention, and the cutter bit 29'-12 located on the outermost side in the radial direction is moved forward in the excavation direction. The cutter bits 29-11, 29-10, ..., 29- whose radial positions are sequentially adjacent to the inner peripheral side of the radial positions of the cutter bits 29'-12.
6, 29-5 are arranged so that the cutting edges are sequentially retracted rearward in the excavation direction. Thus, an excavation surface M1 having an excavation direction excavation surface Ma1 and a radial excavation surface Mr1 and having a substantially stepwise vertical cross-sectional shape is formed.

The second-stage excavation unit 70 includes the first-stage excavation unit 6.
The cutter bit 3 is located at the center of the cutter head 3 in the radial direction. The cutter bit 29-1 located at the center of the cutter in the radial direction is projected forward in the excavation direction. Cutter bits 29-2, 29-3,
The cutting edge of 29-4 is sequentially retracted rearward in the excavation direction, thereby forming an excavation surface M2 having an excavation direction excavation surface Ma2 and a radial excavation surface Mr2 and having a vertical cross-sectional shape substantially in a stepped shape. .

At this time, the cutter bits 29-1 to 29-
11 and 29'-12 have the same structure as the above embodiment of the present invention. That is, a vertical blade surface portion substantially parallel to the excavation direction excavation surface Ma1 (or Ma2), an inclined blade surface portion forming a predetermined inclination angle with respect to the excavation direction excavation surface Ma1 (or Ma2), and a radial excavation surface Mr1 (or It has a horizontal blade surface portion that is substantially parallel to Mr2) and an inclined blade surface portion that forms a predetermined inclination angle with respect to the radially excavated surface Mr1 (or Mr2). It has a negative rake angle and also has a negative rake angle with respect to the radial excavation surface Mr1 (or Mr2).

However, as can be seen from a comparison between FIG. 11 and FIG. 1, the cutter bits 29-1 to 29-4 are different from those of the above-described embodiment of the present invention in that the inner peripheral side and the outer peripheral side in the mounting direction are different. It is upside down. This is for the following reason. That is,
Cutter bits 29-11 to 29-5 of the first stage excavation unit 60
In the second embodiment, the cutter bit 2 of the second stage
This is because, in 9-1 to 29-4, undercutting is performed on the outer peripheral side in excavation in the excavation direction. Also, at the time of radial excavation, in the cutter bits 29-11 to 29-5 of the first stage excavation part 60, the ground to be excavated in the radial direction is on the inner peripheral side, while Step excavation part 7
This is because, in the zero cutter bits 29-1 to 29-4, the ground to be excavated in the radial excavation is on the outer peripheral side.

In the above description, the cutter bit 29
-1 constitutes another preceding excavating means provided on the cutter head in addition to the preceding excavating means provided on the outer peripheral portion of the cutter head.

(IIA) Detailed Excavation Operation and Operation by the Cutter Head of the Shield Excavator of the Present Embodiment The biggest feature of the operation of the shield excavator of the present embodiment is that Is the most protruding cutter bit 29 'on the outermost circumference side
By arranging the cutting edges of the cutter bits 29-11, 29-10,..., 29-6, and 29-5 at other radial positions adjacent to each other in order from -12 so as to be sequentially retracted rearward in the excavation direction, Undercutting is performed while maintaining the vertical cross-sectional shape of the ground excavation surface M1 in a substantially stair-like shape, and in the second-stage excavation section 70, the radial position is from the cutter bit 29-1 most protruding forward in the excavation direction. Cutter bits 29-2 and 29 at other radial positions sequentially adjacent to the outer peripheral side
By arranging the cutting edges of -3 and 29-4 so as to sequentially recede backward in the excavation direction, undercutting is performed while maintaining the vertical cross-sectional shape of the ground excavation surface M2 in a substantially stepped shape. .

That is, in the first-stage excavation section 60 (or the second-stage excavation section 70, the corresponding relation in parentheses, the same applies hereinafter), the cutting bit 29'-12 (or cutter bit 29-1) preceding in the excavation direction makes the excavation surface. A substantially annular preceding excavation surface (or a substantially conical preceding excavation surface) is formed at the radial center of M1 (or M2), and the cutter bits 29-11 to 29-5 are formed using the preceding excavation surface as a foothold. (Or 29-2 ~
29-4) excavates sequentially. As a result, most of the ground excavation surface M1 (or M2) on the inner peripheral side of the preceding excavation surface (or the outer peripheral side of the preceding excavation surface) has a longitudinal cross-sectional shape that is the same as that of the excavation surface Ma1 (or Ma2). Excavation is performed while maintaining a substantially stepped shape including the excavation surface Mr1 (or Mr2). At this time, the surfaces connecting the positions of the blade tips of the cutter bits 29'-12 to 29-5 (or 29-1 to 29-4) are represented by straight lines as is clear from FIG. With such an excavation mode, the root of the substantially step-shaped edge (corner) is pressed by the pressing force of each cutter bit 29 in the excavation direction on the same principle as the above-described embodiment of the present invention. Delamination can be performed that creates and propagates cracks on the sides and continuously induces oblique shear failures on most of the edges. This makes it possible to reduce the excavation force required for excavation, so that excavation of the ground can be performed with a smaller excavation force than in ordinary excavation.

(IIB) Effects of the Shield Machine of the Present Embodiment The effects obtained by the shield machine of the present embodiment having the above-described configuration and operation will be sequentially described below.

(IIB-1) Effects Similar to the First Embodiment of the Present Invention As described in the above (IIA), the shield excavator of the present embodiment also has the same effects as the first embodiment of the present invention. Excavation is mainly performed by exfoliation and crushing in the excavation mode of 1. Therefore, based on the same principle, (1D-1) the effect of improving the excavation distance and (ID-2) described in the embodiment of the present invention.
Cutter driving torque reducing effect, (ID-3) further excavation distance improving effect, (ID-4) further cutter driving torque reducing effect, (1D-5) side drilling effect, (I
D-7) It is possible to obtain the effect of strengthening the excavating power of the preceding excavation part and (ID-8) disposing the sludge injection pipe.

Regarding (1D-6) the effect of pre-excavation on the outer peripheral side, in the present embodiment, the pre-excavation is performed on the outer peripheral side as well as on the center side. The degree to which this effect can be obtained is reduced as compared with the embodiment. However, as compared with the comparative example shown in FIG. 10A, the effect of reducing the amount of collapsed soil and the effect of reducing the occurrence of collapse when the ground collapse occurs can be obtained.

(IIB-2) Effects Specific to the Present Embodiment In the present embodiment, as shown in FIG. 11, the cut-spokes 27A to 27D are bent so that the radial position projecting forward in the digging direction is determined. Two positions (the position of the cutter bit 29'-12 of the first stage excavation unit 60 and the position of the cutter bit 29-1 of the second stage excavation unit 70) are provided. Thus, as in the above-described embodiment of the present invention, the cut-spokes 27A to 27D are formed in a linear shape, and only one radial position protruding forward in the digging direction (the cutter bit 29 'on the radial outer peripheral side) is provided. Compared to the case where only the position of −12) is used, if the number of cutter bits is the same, the size of the cutter head in the direction of excavation (the size in the axial direction) can be reduced.

In particular, as the diameter of the shield becomes larger, the size of the cutter head 3 in the direction of excavation becomes extremely large with only one excavated portion, so that the effect is great. Therefore, the dimension in the excavation direction (machine length) of the entire shield excavator can be reduced accordingly, and the radial dimension of the starting shaft can be reduced. In addition, as the size of the cutter head 3 in the direction of excavation becomes larger, the face excavated surface becomes wider in the diagonal direction, and it tends to cause ground collapse from the spread, and it becomes difficult to perform curve construction and direction correction. The likelihood of occurrence can be reduced.

In one embodiment of the present invention and another embodiment of the present invention, the cutter bit 29 ′ is provided on the radially outer peripheral portion of the cutter head 3 on the forward side in the excavation direction.
-12 is protruded and the cutting edge of the cutter bit 29 is sequentially provided at another radial position adjacent to the radial position so as to be retracted rearward in the excavation direction.
In forming the step excavation section 60 and the second step excavation section 70, the cut-spokes 27 were also formed to have a shape that receded rearward or bent toward the inner peripheral side corresponding to such an arrangement on the cutting edge side. Not limited to That is, the cut-spoke side is configured to simply extend radially in the radial direction like a normal shield machine, and the axial length of the cutter bit attached thereto is changed for each radial position, and Such an arrangement mode of the cutting edge position may be realized. It goes without saying that a similar effect can be obtained in this case as well.

Next, still another embodiment of the present invention will be described with reference to FIG. FIG. 12 is a side sectional view showing the overall structure of a horizontal hole excavator (shield excavator) according to still another embodiment of the present invention. Portions equivalent to those in the above-described embodiment of the present invention and other embodiments of the present invention are denoted by the same reference numerals, and description thereof will not be repeated.

In FIG. 12, the shield machine according to the present embodiment is configured such that the cutter bit 29'-12 at the outer peripheral portion in the radial direction is projected to the foremost side in the excavation direction as in the embodiment of the present invention. Cutter bit 2 sequentially adjacent to the inner circumference
In addition to a first-stage excavation portion 60 for sequentially retreating the cutting edge 9 (details will be described later) to the rear in the excavation direction, a cutter bit 29 ″ slightly outside the radial center portion (central portion) of the cutter head 3 is provided.
-3 protruding forward in the excavation direction, and provided with a third-stage excavation portion 80 in which the cutting edge of the cutter bit 29 (details will be described later) adjacent to the radially outer peripheral side is sequentially retracted rearward in the excavation direction. It is.

That is, the third stage excavation section 80
The cutter bit 29 ″ -3, which is located on the radially center side of the cutter head 3 of the step excavation section 60 and is located slightly on the outer peripheral side from the radially central portion, projects forward in the excavation direction, and the radial position is The cutting edges of the cutter bits 29 "-4 and 29" -2, 29 "-1 adjacent to the outer circumference of the cutter head 3 at the radial position of the cutter bit 29" -3 are sequentially retracted rearward in the excavation direction. Thus, an excavation surface M3 having an excavation direction excavation surface Ma3 and a radial direction excavation surface Mr3 and having a substantially stepwise vertical cross-sectional shape is formed.

At this time, the cutter bits 29 ″ -1,2
9 "-2,29" -4 is basically other cutter bit 2
9-5 to 29-11, and the cutter bit 29 "-3 is the outermost cutter bit 29'-12.
It has a similar structure.

However, in the third-stage excavation section 80, unlike the first-stage excavation section 60 and the second-stage excavation section 70, as shown, the cut spokes 27A to 27D simply extend radially in the radial direction. Cutter bit 29 "-1, 29" -2, 29 "-3
Is changed for each radial position (i.e., the axial length of the cutter bit 29 "-3 is maximized, and then the cutter bits 29" -2, 29 "-4 are increased,
The cutter bit 29 "-1 is made the shortest), and the above-described arrangement of the cutting edge position is realized.

The third-stage excavation section 80 is oriented in such a manner that the cutter bit 29 ″ -4 is undercut to the outer peripheral side in the excavation in the excavation direction (that is, according to the above-described present invention). ), The cutter bits 29 "-2, 29" -1 are oriented in such a manner as to undercut inward in the excavation direction (that is, opposite to the above-described other embodiments of the present invention). In the direction of).

In the above description, cutter bit 2
9 "-3 constitutes another preceding excavating means provided on the cutter head in addition to the preceding excavating means provided on the outer peripheral portion of the cutter head.

In the shield machine according to the present embodiment configured as described above, the excavation operation of the first-stage excavation section 60 is the same as that of the other embodiments of the present invention, and will not be described. In the third-stage excavation section 80, a substantially annular pre-excavation surface is formed in the excavation surface M3 by the cutter bit 29 ″ -3 whose radial position precedes in the excavation direction, and the pre-excavation surface is used as a foothold for each. Cutter bit 29 "-2,2
9 "-1 and 29" -4 perform excavation sequentially. as a result,
Excavation surface M of the ground at the inner and outer peripheral sides of the preceding excavation surface
Excavation is performed while maintaining most of the section 3 in a substantially stair-like shape having a longitudinal cross-section Ma3 and a radial excavation plane Mr3. Exfoliation that causes cracks to develop at the root side of the substantially stepped edge (corner) by the pressing force in the excavation direction of 29 and propagates, and continuously induces oblique shear failure at most of the edge. Crushing can be performed. This makes it possible to reduce the excavation force required for excavation, so that excavation of the ground can be performed with a smaller excavation force than in ordinary excavation.

That is, in this embodiment, the same effects as those of the other embodiments of the present invention can be obtained.

In the above description, the mud taken into the excavation chamber P is discharged by a screw conveyor, and the so-called earth pressure shield excavator which opposes the earth pressure of the face by the pressure of the mud in the excavation chamber P is used. Although the invention has been described by way of example, the invention is not limited to this, and the present invention is not limited to this. The invention may be applied. In this case, a similar effect is obtained.

Further, in the above, the shield body 1
The present invention is applied to a shield machine that excavates by rotating a cutter head 3 provided in front of a pipe. However, the present invention is not limited to this. For example, a push pipe shield, a small-diameter thruster, a TBM, etc. The cutter head structure of the present invention can be applied to the horizontal hole excavator described above, and in this case, the same effect can be obtained.

[0091]

According to the present invention, the excavation is performed by so-called undercutting, so that the excavation force required for excavation can be reduced, and the excavation of the ground can be performed with a small excavation force as compared with ordinary excavation. Becomes possible. Therefore, the wear of the cutter bit due to sliding with the face can be reduced, and the life of the cutter bit can be improved. As a result, the excavation distance can be greatly improved as compared with the normal excavation, and therefore, a sufficiently long excavation can be performed on the soil whose compressive strength is equal to or less than soft rock.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an entire structure of an embodiment of a horizontal hole excavator according to the present invention.

FIG. 2 is a front view as viewed from the direction A in FIG.

FIG. 3 is a partially enlarged view of FIG. 2 showing a detailed structure of a cutter bit constituting the horizontal hole excavator of the present invention.

FIG. 4 is a top view as viewed from a direction B in FIG. 3;

FIG. 5 is a side view as viewed from a direction C in FIG. 3;

FIG. 6 is a partially enlarged view of FIG. 2 showing a detailed structure of another cutter bit constituting the horizontal hole excavator of the present invention.

FIG. 7 is a top view as seen from a direction D in FIG. 6;

FIG. 8 is a side view as viewed from a direction E in FIG. 6;

FIG. 9 is an explanatory diagram illustrating a state where excavation is being performed in the embodiment of the horizontal hole excavator according to the present invention.

FIG. 10 is an explanatory diagram for explaining an operation in the embodiment of the horizontal hole excavator of the present invention.

FIG. 11 is a side sectional view showing the entire structure of another embodiment of the horizontal hole excavator of the present invention.

FIG. 12 is a side sectional view showing the overall structure of still another embodiment of the horizontal hole excavator of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield body 3 Cutter head 27A-D Cutter spoke 29 Cutter bit 29 'Cutter bit 29 "Cutter bit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshifumi Fukawa 2-1-2-2 Konan, Minato-ku, Tokyo Obayashi Corporation Tokyo Head Office (72) Inventor Yoichi Moriya 2-5-2-1, Konan, Minato-ku, Tokyo Obayashi Corporation Tokyo Main Office (72) Inventor Kenji Yamashita 2-2-1 Konan, Minato-ku, Tokyo Obayashi Gumi Tokyo Main Office (72) Inventor Miya Kiyoshi 2-2-1 Konan, Minato-ku, Tokyo Co., Ltd. Obayashi Corporation Tokyo head office (72) Inventor Kiyoshi Tsuchiya 650, Kandamachi, Tsuchiura-shi, Ibaraki Pref.Hitachi Construction Machinery Co., Ltd. F-term in the factory (reference) 2D054 AC02 BA04 BB05

Claims (4)

[Claims] 1. A horizontal hole excavator for excavating by rotating a cutter head provided at a front part thereof, wherein said excavation means is provided on an outer peripheral portion of said cutter head so as to protrude in a propulsion direction; A plurality of cutter bits disposed on the cutter head so as to be sequentially located at the radial position of the cutter head and axially rearward of the horizontal hole excavator. Excavator. 2. A horizontal hole excavator for excavating by rotating a cutter head provided at a front part thereof, wherein said excavating means is provided on an outer peripheral portion of said cutter head so as to protrude in a propulsion direction; From the cutting head in the radial direction and to the rear side in the axial direction of the horizontal hole excavator. A horizontal hole excavator comprising a plurality of cutter bits provided. 3. The horizontal hole excavator according to claim 1, wherein another preceding excavating means is provided on the cutter head in addition to the preceding excavating means provided on an outer peripheral portion of the cutter head. Excavator. 4. A horizontal hole excavator according to claim 3, wherein said another preceding excavating means is provided at a central portion of said cutter head.