JP4137165B2 - Excavation and earthing method, caisson press-fitting method and diameter-excavating device - Google Patents

Description

  The present invention relates to an excavation and earthing method using a casing pipe as a main element for excavation of the ground, a caisson press-in subsidence method, and a diameter expansion excavator, and in particular, in the construction of a vertical shaft by caisson press-in subsidence, The present invention relates to an excavation and excavation method, a caisson press-fitting and subsidence method, and an enlarged diameter excavation device, which improve the efficiency of taking up sediment into a casing pipe when excavating and excavating in a form that expands the bottom or diameter of the blade tip.

  Since the “Ministry of Land, Infrastructure, Transport and Tourism” Law on Special Use for Public Use of Deep Underground was enforced on April 1, 2001 for the purpose of effective use of deep underground. The caisson press-in construction method is attracting attention as a construction method. Against this background, the need for caisson press-in method for underground space utilization tends to be deep and large diameter, and sometimes caisson press-in method is used even on hard ground.

  In the caisson press-in installation method on hard ground, as a drilling method, for example, a plurality of enlarged diameter drilling blades are radially attached to the outer periphery of the casing pipe, and then the casing pipe is used as a gripping part to rotate with a fully swivel all-casing excavator. Is excavating hard ground. In particular, it is possible to actively excavate under the cutting edge of the caisson by positioning the expanded drilling blade in a reduced diameter state under the cutting edge of the caisson and then expanding and rotating the expanding drilling blade. .

Many of these diameter-expanded excavators are, for example, on the front side of the intersection of the diameter-excavated blade and the casing pipe (front side in the excavation rotation direction) as described in Patent Documents 1 and 2 proposed by the present applicant. An opening (sediment intake port) is provided on the side surface of the casing pipe. And the earth and sand excavated by the enlarged diameter excavating blade are taken into the casing pipe from this opening, and the taken-in earth and sand are discharged by a lifting and discharging means such as a hammer grab or a grab bucket.
JP 2004-176530 A Japanese Patent Laid-Open No. 10-317376

  In the thing of patent document 1, although the disk called a top disk part is arrange | positioned just above the diameter-expanded excavation blade, the upper space of the diameter-expanded excavation blade tends to be substantially blocked. On the other hand, in the thing of patent document 2, although there is a difference that the upper space of the diameter-expanded excavation blade is substantially opened without the presence of the disk, the excavated earth and sand are in any case. In order to quickly and efficiently take it into the casing pipe, the excavated earth and sand does not get over the enlarged diameter excavating blade, and is pushed by the rotating enlarged diameter excavating blade. It is desirable to be introduced into the earth and sand intake opening formed in the pipe.

  However, as mentioned earlier, the distance from the outer peripheral edge of the expanded excavation blade to the sediment intake port tends to increase with the caisson's large diameter, and the excavated earth and sand can be smoothly taken into the sediment intake port. Is becoming difficult. In other words, as the distance from the outer peripheral edge of the enlarged diameter drilling blade to the soil intake port increases as described above, the amount of excavation per expanded diameter drilling blade increases, while the excavated earth and sand becomes The amount of climbing over is also increased, and as a result, the amount of earth and sand that circulates and circulates together with the enlarged diameter excavating blade increases, and the efficiency of taking in the earth and sand intake port decreases.

  In particular, when a large-diameter excavation (for example, a diameter of 5 m or more) is performed on a mudstone-based ground, the technique described in Patent Document 1 substantially uses an upper space of the enlarged-diameter excavation blade as a disk. Because of the tendency to be clogged, the excavated earth and sand may stay near the intersection of the expanded excavation blade and the disk, and the accumulated earth and sand may increase as the excavation continues, closing the earth intake port. In addition, there was a possibility that earth and sand would accumulate to the upper part of the disk, and that the gripping ability of the all-swivel all-casing excavator could be exceeded due to the increase in the total weight of earth and sand.

  On the other hand, in the technique described in Patent Document 2, when the excavated earth and sand gets over the upper diameter excavating blade, the earth and sand is collected by the subsequent larger diameter excavating blade. As the sediment that rotates and circulates along with the blades, the excavated sediment and water are mixed and agitated, and the excavated sediment is sludged (cattle). This caused troubles such as adhesion to the inner surface and blockage of the earth and sand intake port, and the extra disposal was required for the secondary disposal of the mud that had become the bottom mud.

  Thus, there is a demand for effective excavation and excavation technology and widening excavation technology for a wide variety of soil types as well as diversification and enlargement of caisson press-fitting method, and the present invention meets such a demand. It was made to respond.

  That is, the present invention is based on the same excavation and excavation technology as in Patent Documents 1 and 2, and includes an excavation and excavation method, a caisson press-fitting subsidence method, and a diameter-expanding excavator that improve the efficiency of taking excavated soil into the sediment intake It is to provide.

The invention according to claim 1 is provided with a plurality of excavating blades projecting radially on the outer periphery of a casing pipe that is press-fitted in a vertically downward direction while being rotationally driven. An opening is formed on the front side in the rotational direction from the intersection of the two, and by rotating the casing pipe together with the excavating blade, the ground is excavated using at least the lower end of the excavating blade as an excavation point, and at least the excavated soil It is assumed that the method is to guide a part along the excavating blade and take it into the casing pipe through the earth and sand intake and discharge it.

In addition, the excavation blade has a shape in which a portion above the excavation point covers the front side in the rotation direction with respect to the excavation point in a cross section perpendicular to the projecting direction of the excavation blade itself, and the excavation blade itself In the cross section perpendicular to the projecting direction, the surface on the front side in the rotational direction has a concave shape, and the earth and sand excavated by the excavating blade is guided forward in the rotational direction of the excavating blade and above the excavation point. Then, it is taken into the casing pipe and discharged.

Desirably, as described in claim 2, the tip end side far from the casing pipe covers the front side in the rotational direction with respect to the root portion side close to the casing pipe in plan view, and excavated by the excavating blade The earth and sand thus obtained are guided forward in the rotational direction of the excavating blade and upwardly from the excavation point, and are guided in the direction of the earth and sand intake to be taken into the casing pipe and discharged.

More preferably, as described in claim 3, the excavating blade has a concave surface on the front side in the rotational direction in plan view.

In particular, in preparation for excavation under the cutting edge of a caisson, as described in claim 4, the excavation blade itself expands and contracts with a fixed excavation blade and a movable excavation blade movable in parallel to the fixed excavation blade. It is desirable that the trajectory drawn by the tip of the movable excavation blade with rotation can be expanded or contracted according to the excavation diameter.

In this case, as described in claim 5, the movable excavating blade covers the tip end side far from the casing pipe in a stepwise manner toward the front side in the rotational direction with respect to the root side near the casing pipe in a plan view. In this way, the surface having the incident angle of one or more stages is formed, or the shape of the movable excavator blade itself in plan view is curved with a curve, so that the surface on the front side in the rotational direction is concave in plan view. It shall be.

  The shape curved with a curve here refers to a shape curved with a so-called quadratic curve such as a parabola or a logarithmic spiral as well as a simple circle.

For example, when excavating hard ground, as described in claim 6, excavating a preceding excavation hole having a diameter larger than the casing pipe diameter and smaller than a minimum excavation diameter that can be excavated by an excavating blade, It is desirable that the earth and sand excavated by the excavating blade is taken into the preceding excavation hole through the gap between the casing pipe and the preceding excavation hole and discharged.

In any of the above excavation methods, as means for earth removal of sediment captured in the casing, and bucket dumping means according to claim 7, and those using mud formula dumping means according to claim 8 To do.

The invention according to claim 9 specifies the method of press-fitting caisson with the excavation and earthing method according to claim 4 or 5, and the excavation blade is in a contracted state below the cutting edge of the caisson By extending the excavation blade after positioning the tip, the trajectory drawn by rotation of the tip of the movable excavation blade forming a part of the excavation blade is expanded, and the excavation blade is in an expanded state. It includes a step of excavating under the cutting edge of the caisson with an excavation diameter larger than at least the inner diameter of the caisson, and a step of press-fitting and inserting the caisson after the diameter expansion excavation under the cutting edge.

Therefore, in at least the invention described in claim 1, the excavation blade has a shape in which a portion above the excavation point covers the front side in the rotation direction with respect to the excavation point in a cross section perpendicular to the protruding direction of the excavation blade itself. In addition, since the surface on the front side in the rotational direction has a concave shape in the cross section perpendicular to the projecting direction of the excavating blade itself , the excavated earth and sand is difficult to get over the excavating blade, and the excavated earth and sand is used as the earth intake port. It becomes easier to introduce, and the efficiency of taking up sediment into the casing pipe is improved.

The invention according to claim 10 substantially captures the technique according to claim 1 as a diameter-expanded excavator, and the excavation blade is movable in parallel with the fixed excavation blade and the fixed excavation blade. The trajectory drawn by the tip of the movable excavating blade as it rotates is configured to be able to expand and contract according to the excavation diameter. In the cross section perpendicular to the moving direction of the fixed excavation blade, the upper portion of the excavation point covers the front side of the excavation direction with respect to the excavation point.

In this case, as described in claim 11, it is desirable that the fixed excavation blade has a concave shape on the front surface in the rotational direction in the cross section orthogonal to the longitudinal direction of the fixed excavation blade. .

Further, as described in claim 12, in place of the movable excavation blade according to claim 10 or 11 , the movable excavation blade has a tip portion far from the casing pipe with respect to a root portion side close to the casing pipe in a plan view. The side may be covered with the front side in the rotation direction, and the surface on the front side in the rotation direction may be concave in the cross section orthogonal to the moving direction of the fixed excavation blade itself.

In this case, as described in claim 13, it is desirable that the movable excavating blade has a concave shape on the front surface in the rotational direction in plan view.

Furthermore, as described in claim 14, the movable excavation blade is configured so that the tip end side far from the casing pipe is stepped toward the front side in the excavation progress direction with respect to the base portion side close to the casing pipe in a plan view. The surface on the front side in the rotational direction in the plan view has a concave shape by making it a shape having an incident angle of one or more steps, or by making the plan view shape of the movable excavator blade itself curved. Is desirable.

Further, in the case of assuming the diameter expanding excavator according to claim 10, as described in claim 15, the movable excavator blade has a cross section perpendicular to the moving direction of the movable excavator blade with respect to the fixed excavator blade. The amount of fogging, which is the degree of the shape where the upper part of the excavation point covers the front side in the rotational direction, is directed from the distal end side of the movable excavating blade farther from the casing pipe to the root side closer to the casing pipe. It is desirable to set it so that it gradually becomes smaller.

In any of the diameter-expanded excavators according to claims 10 to 15, as described in claim 16 , the casing pipe is provided with a plurality of tangential directions of the casing pipe in a plan view. It is assumed that the excavating blades are provided at an equal pitch, and further, as described in claim 17, the excavating blades can be excavated at a position below the excavating blades in the casing pipe and larger than the casing pipe diameter. It is assumed that a pre-excavation blade for excavating a pre-excavation hole having a diameter smaller than the minimum excavation diameter is provided.

Therefore, in particular, in the invention described in claim 15, the fogging amount in the movable excavating blade is formed in a so-called gradual deformation shape so that the moving excavating blade gradually decreases from a portion far from the casing pipe to a portion close to the casing pipe. For this reason, the earth and sand pushed by the excavating blades can be guided to the base side of the excavating blades due to the guiding effect due to the gradual change of the cover amount. This means that the earth and sand easily enter the earth and sand intake port, and the efficiency of earth and sand intake into the casing pipe is further improved.

Such sediment-induced effects, as described in claim 13, the movable drilling wing is a surface of the rotation direction front side in plan view is formed as a concave shape, it becomes more pronounced.

According to the invention described in claim 1, Yu and and rotation direction front side of the so-called fog in the cross-sectional shape faces the excavated earth and sand by the drilling wing has a concave shape, excavation advancing direction of the excavating blade Since it is guided to the front and above and taken into the casing pipe and discharged, it is difficult for the excavated earth and sand to get over the excavating wing, and the earth and sand pushed by the excavating wing are guided to the base side of the excavating wing. Therefore, it becomes easier to introduce excavated earth and sand into the earth taking-in port, and the efficiency of taking earth and sand into the casing pipe is improved. In particular, the above- described effect becomes more remarkable when the cross-sectional shape of the excavating blade is a concave surface on the front side in the rotational direction as described above.

According to the invention described in claim 2, drilling wing in addition to the surface of the organic and and rotating forward side a so-called head in cross section has a concave shape, the planar shape of the drilling blade Since the shape of the excavator blade is a so-called foggy shape, or because the surface on the front side in the rotational direction is concave , the earth and sand pushed by the excavator blade can be more reliably removed As a result, it becomes easier to introduce excavated earth and sand into the earth intake port, and the efficiency of taking earth and sand into the casing pipe is dramatically improved.

According to the fourth aspect of the present invention, the excavating blade itself can be expanded and contracted, and can be expanded or contracted according to the excavation diameter, so that excavation can be flexibly dealt with regardless of the excavation diameter. Therefore, the versatility is enhanced, and this is particularly advantageous when excavating under the cutting edge of a caisson.

According to the sixth aspect of the present invention, the excavation of the preceding excavation hole allows the earth and sand excavated by the excavating blade to be taken into the preceding excavation hole through the gap between the casing pipe and the preceding excavation hole and discharged. In particular, it is possible to cope with excavation of hard ground without difficulty, and it is also possible to reliably take in and discharge excavated soil.

According to the invention described in claim 9 , since the caisson press-fitting and sinking is performed on the premise of the excavation and soiling method as described above, it greatly contributes to the shortening of the construction period of the caisson by improving the sediment intake efficiency. become able to.

According to the invention described in claim 10, since the technique described in claim 4 is specified as a diameter expanding excavator, the same effect as the invention described in claim 4 can be obtained.

  1 to 8 show a more specific first embodiment of the excavation and earthing method and the expanded-diameter excavator according to the present invention. In particular, FIG. 1 shows a cutting edge (blade surface) 1a of a caisson 1 under a hard ground. The entire apparatus for reducing the press-fitting resistance under the cutting edge of the caisson 1 by expanding the diameter below (hereinafter referred to as the cutting edge) of the caisson 1, and press-fitting the caisson 1 while adding the segments which are constituent elements of the caisson 1 The schematic structure of is shown.

  Here, in the caisson press-fitting method, when the excavated ground is hard ground, the press-fit resistance becomes enormous due to the ground resistance under the cutting edge of the caisson. Therefore, when excavating the caisson in place after excavating the place to be a wall with caisson and replacing the earth and sand, and using a drilling device capable of expanding the caisson under the tip of the caisson, the inside of the caisson and under the tip of the caisson In some cases, the caisson is gradually press-fitted and submerged while excavating, but here, an example of application to the latter method is shown.

  1 is roughly divided into a casing pipe 2, for example, three sets of blade-shaped excavating blades 3 arranged radially around the tip of the casing pipe 2, and the casing pipe 2. A rotary push-in device 4 functioning as a driving device, a plurality of press-fitting jacks 5 as press-fitting and sinking devices for sequentially press-fitting caisson 1, and a crawler crane or the like (not shown) are suspended and supported. It is composed of a hammer grab 6 or the like that functions as lifting and discharging means for carrying out the earth and sand introduced therein.

  The rotary push-in device 4 has a function equivalent to that of a drive unit of an all-swivel all-casing excavator. After the casing pipe 2 is chucked (gripped), it is rotated in a clockwise direction in a plan view, for example. And a function of applying thrust to the casing pipe 2 and press-fitting it into the ground in parallel with the rotational driving of the casing pipe 2. The press-fitting jack 5 has a function of press-fitting and setting the entire caisson 1 below the press-fitting plate 7.

  2 is an enlarged view of the main part of the casing pipe 2, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a sectional view taken along line BB in FIG. Show. As described above, the three excavation blades 3 are radially arranged on the outer periphery of the tip of the casing pipe 2 so as to be directed in the diameter direction or the tangential direction, and below the spiral auxiliary blade 8. In addition, a three-blade leading excavation blade 9 is also mounted. A fixed excavation blade that forms a flat excavation blade 3 with respect to each blade bracket 10 is fixed to a three-fold position on the outer peripheral surface of the cylindrical body of the casing pipe 2. 12 is fixed with a plurality of bolts 11. Thereby, each excavation blade 3 is attached at equal pitches so as to be directed in the tangential direction of the casing pipe 2.

  Each excavation blade 3 is arranged so that a movable excavation blade 13 narrower than the flat excavation blade 12 and curved in a substantially arcuate shape in plan view is superimposed on the flat excavation blade 12. Whereas the width dimension (vertical direction dimension in FIG. 2) gradually decreases from the root portion side toward the tip end side, the movable excavating blade 13 has a shape with a substantially constant width dimension. It has become. As shown in FIG. 4, the movable excavation blade 13 is slidably supported by a pair of upper and lower linear guides 14 with respect to the fixed excavation blade 12, that is, is guided and supported so as to be movable in parallel. Between the blades 13, a hydraulic cylinder 15 is arranged in a bridging manner as a direct acting actuator.

  More specifically, while the cylinder tube of the hydraulic cylinder 15 is fixed to the back side of the fixed excavation blade 12, the tip of the piston rod is movable via a bracket 16 that penetrates the fixed excavation blade 12 in the thickness direction. It is connected to the excavating blade 13. Accordingly, the movable excavation blade 13 can move forward and backward with respect to the fixed excavation blade 12, and when the movable excavation blade 13 is extended with respect to the fixed excavation blade 12 by the extension operation of the hydraulic cylinder 15, it is shown in FIGS. In contrast, when the movable excavation blade 13 is contracted with respect to the fixed excavation blade 12 by the contraction operation of the hydraulic cylinder 15, it is set so that the diameter reduction state is as shown in FIGS. The entire excavating blade 3 has a structure capable of expanding and contracting.

  The diameter of the locus drawn by the maximum diameter portion at the tip of the excavating blade 3 is set to be at least larger than the inner diameter of the caisson 1 to be press-fitted as shown in FIG. Conversely, the diameter of the locus drawn by the maximum diameter portion at the tip of the excavating blade 3 in the reduced diameter state is set to be smaller than at least the inner diameter of the caisson 1 to be press-fitted as shown in FIG. .

  In addition to the lower surface of the fixed excavation blade 12 forming the excavation blade 3, a plurality of excavation blades (bits) 17 are implanted on the lower surface of the movable excavation blade 13 and the front end surface in the longitudinal direction. . Therefore, whether the excavating blade 3 is in a reduced diameter state or in an expanded state, or an intermediate state between the expanded state and the reduced diameter state (transient state from the expanded state to the reduced state or vice versa). Regardless of whether it is in a transitional state from a diameter state to an expanded state), if the rotational force and the excavation thrust are applied to the excavation blade 3 together with the casing pipe 2, the excavation blade 3 is positive in any state. Drilling is possible. That is, if a rotational force and excavation thrust are applied to the excavation blade 3 together with the casing pipe 2, the ground can be actively excavated using at least the excavation blade 17 at the lower end of the excavation blade 3 as shown in FIG. It has become. In addition, the lower surface of the fixed excavation blades 12 forming each excavation blade 3 is partially tapered, so that at least the central portion of the trajectory drawn by the lower surface of the excavation blade 3 by its rotation is substantially conical. It is set to become.

  As shown in FIG. 5 in addition to FIG. 3, the movable excavation blade 13 forming the excavation blade 3 has an axis of the fixed excavation blade 12 (the moving direction of the movable excavation blade 13 relative to the fixed excavation blade 12 or the fixed excavation blade 12. The longitudinal axis) of the tip is bent or curved in a stepwise manner forwardly in the rotational direction (front side in the excavation direction) with two incident angles θ1 and θ2 as a reference. The movable excavating blade 13 is substantially curved in a plan view, and the movable excavating blade 13 is substantially in the shape of a forward blade that is concave toward the front side in the rotational direction or the forward direction in the excavation direction in the plan view. Is formed. As described above, the movable excavating blade 13 is formed in a forward blade shape that is concave in the rotational direction in plan view, and the distal end on the outermost diameter side of the movable excavating blade 13 will be described later in the rotational direction. It is always located in front of the earth and sand intake port 21.

  That is, as shown in FIG. 5, the movable excavation blade 13 has a stepped step toward the front side in the rotation direction or the front side in the excavation progress direction with respect to the root side near the casing pipe 2 in the plan view. The sum of these incident angles θ1 and θ2 is the amount of fog in the rotational direction of the movable excavating blade 13 in plan view. As a result, as will be described later, the earth and sand excavated by the excavating blade 3 is guided toward the front side and the upper side in the rotational direction of the excavating blade 3 or the excavation traveling direction.

  As shown in FIG. 4, the movable excavation blade 13 forming the excavation blade 3 is provided with a so-called bowl-shaped earth and sand return plate 18 along its longitudinal direction. The earth-and-sand return plate 18 includes an upper plate 19 extending perpendicularly from the upper end of the movable excavating blade 13 and an oblique plate disposed at an angle θ3 so as to straddle the upper plate 19 and the movable excavating blade 13 itself. The movable excavation blade 13 has a cross section perpendicular to the longitudinal direction of the movable excavation blade 13 (the movement direction of the fixed excavation blade 12), or the excavation direction in the rotational direction. It is formed as a so-called forward wing shape that is concave toward the front side in the traveling direction.

  That is, the movable excavation blade 13 has a so-called forward blade shape that is concave toward the front side in the rotation direction or the front side in the excavation progress direction in a cross section perpendicular to the projecting direction or the longitudinal direction of the excavation blade 3 itself. By being formed, the portion located above the excavating blade 17 with respect to the excavating blade 17 serving as the lower excavation point is shaped to cover the rotational direction front side or the excavation progress direction front side, The fogging amount α, which is the degree of the concave shape of the forward blade shape, is set to be substantially constant in the longitudinal direction. As a result, as will be described later, the earth and sand excavated by the excavating blade 3 is guided toward the front side and the upper side in the rotational direction of the excavating blade 3 or the excavation traveling direction.

  As shown in FIGS. 2 and 4, the casing pipe 2 is located at substantially the same height as the root of each excavation blade 3 and interferes with the excavation blades 3 on the front side in the rotational direction of each excavation blade 3. A substantially rectangular earth and sand intake port 21 is formed in two upper and lower stages so as to communicate between the inside and the outside of the casing pipe 2 at a position where the casing pipe 2 and the excavation blade 3 intersect. As will be described later, these earth and sand intake ports 21 positively take in the earth and sand collected on the root side of the excavation blade 3 and on the front side in the rotation direction as the excavation blade 3 rotates. Will play a role.

  Further, a spiral auxiliary wing 8 is attached to a position below the mounting position of the excavating blade 3 in the casing pipe 2, and a substantially square shape is seen in a plan view at a position below the auxiliary wing 8. The three leading excavation blades 9 bent radially are arranged radially. More specifically, as shown in FIG. 6, a casing attachment 22 having substantially the same diameter, which forms a part of the casing pipe 2, is detachably attached to the tip of the casing pipe 2. For example, three preceding excavation blades 9 that are bent in a substantially U shape in plan view are mounted on the outer periphery of 22. This leading excavation blade 9 has a plurality of excavation blades 24 planted at the lower end of a blade 23 bent in a substantially U shape in plan view, and the back side is reinforced by a reinforcing plate 25. In the cylindrical body portion of the casing attachment 22, an approximately rectangular earth and sand intake 26 is formed at the same height position as the preceding excavation blade 9 at the front side in the rotation direction of the root portion so as to be close to each preceding excavation blade 9. It is.

  And the diameter of the locus which the tip (maximum diameter portion) of each preceding excavation blade 9 draws by the rotation, that is, the excavation diameter is naturally larger than the outer diameter of the casing pipe 2 (casing attachment 22) and is in a reduced diameter state. The excavation blade 3 (the state of FIGS. 7 and 8) is set smaller than the diameter of the locus drawn by the rotation. A plurality of excavating blades 27 are planted at the lower end of the casing attachment 22.

  Therefore, according to the present embodiment, as shown in FIG. 1, a predetermined excavation thrust (digging force) is applied while rotating the casing pipe 2 in the clockwise direction, and the caissons 1 are formed by the plural excavation blades 3. The caisson 1 is gradually press-fitted and submerged while excavating under the cutting edge of the blade so as to be larger than the inner diameter of the caisson 1 itself. As the caisson 1 is pressed and set, the caisson 1 itself is added to the upper side, and the casing pipe 2 is also added with a predetermined tube attachment.

  That is, in FIG. 1, each excavation blade 3 is in a diameter-expanded state as shown in FIG. 2 and FIG. 3, so that a predetermined excavation thrust (digging force) is generated while the casing pipe 2 is driven to rotate clockwise. When applied, the lowermost end of the casing pipe 2 leads into the ground first, and the earth and sand corresponding to the diameter of the casing pipe 2 is cut out from the surrounding earth and taken into the casing pipe 2, and the leading excavation blade 9 has the excavation diameter D1 in FIG. The ground is excavated and the excavated earth and sand is taken into the casing pipe 2 from the earth and sand intake 26. On the other hand, outside the casing pipe 2, each of the drilling blades 3 in the expanded state excavates the ground with a large diameter, and the excavated earth and sand are gradually gathered near the canning pipe 2, Part of the earth and sand is dropped into the excavation hole that has been excavated by the preceding excavation blade 9, and the remaining part of the earth and sand is taken into the casing pipe 2 from the earth and sand intake port 21. That is, as shown in FIG. 1, so-called three-stage stepped hole excavation is performed by excavation by the tip of the casing pipe 2, excavation by the enlarged diameter excavation blade 9 and further excavation by the excavation blade 3. .

  At this time, the spiral auxiliary wing 8 positioned directly below the earth and sand intake 21 pushes the earth and sand dropped into the excavation hole excavated by the preceding excavation wing 9 below the position of the auxiliary wing 8. In this way, the excavation efficiency of the excavated sediment from the sediment intake 26 is improved.

  Regardless of whether the excavating blade 3 is in a diameter-expanded state or a diameter-reduced state, the diameter-expanded or diameter-reduced state can be obtained by hydraulically locking the hydraulic supply path of the expansion-contraction diameter hydraulic cylinder 15. Is self-retained.

  In parallel with the progress of such excavation, the earth and sand taken into the casing pipe 2 is discharged by, for example, the hammer grab 6 shown in FIG.

  Here, the movable excavation blades 13 forming the excavation blades 3 each have a sediment return plate 18, and the cross section perpendicular to the longitudinal direction of the movable excavation blades 13 themselves is the front side in the rotational direction or the excavation progress. Since it is formed as a so-called forward-facing blade shape that becomes concave toward the front side in the direction, the excavated earth and sand will stay on the front side of the movable excavating blade 13, but the movable excavating blade 13 The earth does not get over the upper side, and the earth and sand excavated by the excavating blade 17 on the lower side of the movable excavating blade 13 is directed toward the front side in the rotational direction of the excavating blade 3 or the excavation progressing direction as shown in FIG. In addition, it is guided toward the upper side of the lower excavation blade 17 that is the excavation point, and as a result, it is pushed to the front side of the excavation blade 3 while repeatedly turning in the vertical direction as indicated by an arrow M1 in FIG. It will be. As a result, the amount of earth and sand pushed to the front side with the rotation of the excavation blade 3 is increased as compared with the conventional method, so that the sediment dropping efficiency into the excavation hole excavated by the preceding excavation blade 9 or the sediment intake is increased. Incorporation efficiency of earth and sand from the mouth 21 into the casing pipe 2 is improved.

  On the other hand, the movable excavating blade 13 forming the excavating blade 3 is formed as a so-called forward-facing blade shape whose cross section is concave toward the front side in the rotational direction or the forward direction in the excavation direction as described above. In addition, the movable excavating blade 13 is formed as a so-called forward blade shape having a concave shape toward the front side in the rotational direction or the front side in the excavation progress direction in plan view, as shown in FIG. As the earth and sand collected at the outer diameter side tip (the part far from the casing 2), the guiding direction of the movable pipe 13 is rotated by the rotation of the movable excavating blade 13 itself, that is, as indicated by the arrow M2, the casing pipe 2 It will be oriented in the center direction.

  This means that the excavated earth and sand are actively collected near the outer peripheral surface of the casing pipe 2 gradually as each of the excavating blades 3 is rotated. Therefore, dropping of earth and sand into the excavation hole or taking in of earth and sand from the earth and sand intake port 21 into the internal space of the casing pipe 2 is further promoted. Such a function is not only when the excavating blade 3 is in a diameter-expanded state as shown in FIGS. 2 and 3, but also when the excavating blade 3 is in a diameter-reduced state as shown in FIGS. Even when in a transient state,

  As described above, according to the present embodiment, the movable excavation blade 13 is formed in a so-called forward blade shape in which the cross section is concave toward the front side in the rotational direction or the front side in the excavation progress direction. In addition, since it is formed as a so-called forward-facing blade shape that is concave toward the front side in the rotation direction or the front side in the excavation progressing direction in plan view, in particular, the earth and sand can be collected together with the sediment collection efficiency or displacement efficiency by the excavation blade 3 The efficiency of taking in the casing pipe 2 from the intake port 21 is improved, and the efficiency of dropping the earth and sand excavated by the excavating blade 3 into the preceding excavation hole, and the same efficiency of taking in the soil from the earth intake port 26 into the casing pipe 2 as well. Will be improved dramatically.

  In the above embodiment, the earth and sand return plate 18 is attached only to the movable excavation blade 13, but it is of course possible to similarly provide the earth and sand return plate 18 to the fixed excavation blade 12 as described later. is there. Further, the width dimension of the earth and sand return plate 18 shown in FIG. 4 (the fogging amount α shown in FIG. 4) is substantially constant in the longitudinal direction, but the width dimension is close to the casing pipe 2 as necessary. It is good also as a shape which decreases gradually as it becomes.

  Furthermore, in the said embodiment, although the hammer grab 6 which is a bucket-type earth removal means is used as a means for discharging the earth and sand taken in in the casing 2, what kind of thing is used as an earthing means. For example, it is possible to employ a muddy water type earth discharging means instead of the hammer grab 6. In this case, as shown in FIG. 9, a sand pump 60 is introduced near the bottom of the hole at the tip of the casing 2, and the excavated sediment is once sucked up together with water in the discharge pipe 61 and stored in a sedimentation tank (not shown). After sedimentation and sieving, the water after sedimentation and sieving is returned to the hole as reused mud. Alternatively, instead of the sand pump 60 shown in FIG. 9, compressed air is introduced from the ground-side compressor to the same position as the sand pump 60, while the muddy digging earth and sand is once put on the ground by the discharge pipe 61 using the floating force of the air. Muddy water called so-called air lift system that discharges and stores in a sedimentation tank (not shown), and then sediments and sifts the sediment in the same manner as above, and returns the sedimented and sieved water to the hole as reused mud. A soil removal method may be adopted.

  FIGS. 10-12 shows the modification of the earth-and-sand return plate attached to the movable excavation blade 13 as 2nd Embodiment of this invention. In FIGS. 10 to 12, the same reference numerals are given to parts common to the first embodiment.

  The earth and sand return plate 18 of the first embodiment shown in FIG. 4 is formed by the upper plate 19 and the inclined plate 20, whereas in the second embodiment shown in FIGS. A single-plate earth and sand return plate 38 bent in a substantially U-shaped cross section is mounted obliquely upward on the front surface of the movable excavating blade 13. 11A is a cross-sectional view taken along line aa in FIG. 10, FIG. 11B is a cross-sectional view taken along line bb in FIG. 10, and FIG. 11C is a cross-sectional view taken along line cc in FIG. As shown in these figures, the earth and sand return plate 38 is formed to have a uniform cross-section throughout the entire length of the movable excavating blade 13.

  In other words, as the movable excavation blade 13 of the excavation blade 3 shown in FIGS. 10 and 11 is provided with the earth and sand return plate 38, as is clear from FIG. In a cross section perpendicular to the longitudinal direction, a shape in which a portion above the excavation blade 17 covers the front side of the excavation traveling direction with respect to the position of the excavation blade 17 that is the excavation point, that is, the moving direction or longitudinal direction of the movable excavation blade 13 In the cross section perpendicular to the direction, it is formed as a forward blade shape having a concave shape toward the front side in the excavation progress direction.

  As is clear from FIG. 10, the movable excavation blade 13 has incident angles θ1 and θ2 in plan view as in the previous embodiment, and is therefore close to the casing pipe 2 in plan view. The tip end side far from the casing pipe 2 with respect to the base portion side is covered with the front side in the excavation progress direction, that is, in the shape of a forward blade that becomes concave toward the front side in the excavation progress direction in plan view. .

  Therefore, also in the second embodiment in which the shape of the earth and sand return plate 38 is different, the same operational effects as those in the first embodiment shown in FIG. 4 can be obtained.

  That is, FIG. 12 shows the state of excavation of the earth and sand in the cross section of (A) of FIG. 11, and excavation earth and sand are guided in the order of (A), (B), and (C) of FIG. In particular, the earth and sand excavated by the excavating blade 17 on the lower side of the movable excavating blade 13 is gradually gathered by the movable excavating blade 13 toward the front side in the excavation direction. And as shown to the same figure (B) and (C), with the progress of excavation, the amount of excavated earth and sand increases so that it rises diagonally upward along the inclination of the sediment return plate 38. However, since the earth and sand where the rise has reached the limit will collapse to the front side of the excavation progress direction as shown in the figure, the earth and sand will not get over the earth and sand return plate 38, and finally the earth and sand While being pushed forward by the movable excavating blade 13 in the direction of excavation, the excavating blade 3 has a predetermined amount of cover as shown in FIG. As guided by the excavation blades 12, the excavation blades 3 are gradually guided to the base portion side of the excavation blades 3, and eventually to the earth and sand intake port 21 side under the locus M2 in FIG.

  13 and 14 are diagrams showing third and fourth embodiments of the present invention.

  In the third embodiment shown in FIG. 13, as is clear from FIG. 5, the movable excavation blade 33 forming the excavation blade 3 faces the front side in the rotational direction or the forward direction in the excavation progress direction in plan view. In forming a so-called forward-facing blade shape having a concave shape, the number of stages for bending or curving its tip toward the front side in the rotational direction or the front side in the excavation progress direction is increased from that in FIG. is there. That is, the movable excavation blade 33 is bent or curved toward the front side in the rotation direction or the front side in the excavation progress direction in four stages of θ11 to θ14. The sum total of θ11 to θ14 is the amount of fog for the movable excavating blade 33 to have a concave forward blade shape toward the front side in the rotation direction or the front side in the excavation progress direction in plan view.

  Further, in the fourth embodiment shown in FIG. 14, as is clear from the comparison with FIG. 5, the movable excavation blade 43 forming the excavation blade 3 is in the front side in the rotational direction or the forward side in the excavation progress direction in plan view. When forming a so-called forward-facing blade shape that becomes concave toward the top, the tip is bent or curved with a smooth arcuate surface toward the front side in the rotational direction or the front side in the excavation progress direction. Of course, the arcuate surface includes not only a simple circular shape but also a curvature shape of a quadratic curve such as a parabolic shape or a logarithmic spiral shape.

  In these third and fourth embodiments, it goes without saying that the same operational effects as those of the first embodiment can be obtained.

  15 and 16 are diagrams showing fifth and sixth embodiments of the present invention. In these fifth and sixth embodiments, the same reference numerals are given to the portions common to the previous first embodiment.

  In the fifth embodiment shown in FIG. 15, the movable excavating blade 13 forming the excavating blade 3 faces the front side in the rotational direction or the forward direction in the excavation progressing direction as apparent from the comparison with FIG. In forming a so-called forward blade shape having a concave shape, the slanted plate 30 itself forming the bowl-shaped sediment return plate 18 is also concave toward the front side in the rotational direction or the front side in the excavation progress direction. The one bent in a substantially U-shaped cross section is adopted.

  Further, in the sixth embodiment shown in FIG. 16, as is clear from FIG. 4, the movable excavating blade 13 forming the excavating vane 3 is in the rotational direction front side or the excavation forward direction front side in the cross section. When forming a so-called forward-facing blade shape that is concave toward the front, the slanted plate 40 itself that forms the bowl-shaped sediment return plate 18 is also directed forward in the rotational direction or forward in the excavation progress direction. What is bent into a circular arc shape so as to have a concave shape is adopted. Of course, the arcuate surface includes not only a simple circular shape but also a curvature shape of a quadratic curve such as a parabolic shape or a logarithmic spiral shape.

  According to the fifth and sixth embodiments, there is an advantage that the amount of earth and sand retained in the cross section of the movable excavating blade 13 is further improved.

  FIGS. 17 and 18 are views showing a seventh embodiment of the present invention, and the same reference numerals are given to the portions common to the first embodiment.

  As shown in FIGS. 17 and 18, the movable excavation blade 53 forming the excavation blade 3 is a so-called flat plate without bending or curving its tip in plan view as in the first embodiment. On the other hand, the flat movable excavating blade 53 is provided with a so-called bowl-shaped earth and sand return plate 28 along its longitudinal direction. Thereby, the movable excavation blade 53 has a so-called parallel movable form with respect to the fixed excavation blade 12.

  The earth-and-sand return plate 28 has an upper plate 39 extending from the upper end of the movable excavation blade 53 at a right angle to the upper surface 39, and an oblique plate arranged at an angle β so as to straddle the upper plate 39 and the movable excavation blade 53 itself. 50, the movable excavation blade 53 has a section perpendicular to the longitudinal direction of the movable excavation blade 53 (the moving direction of the excavation blade with respect to the fixed excavation blade 12). It is formed as a so-called forward wing shape that is concave toward the front side in the traveling direction. Further, the cover amount W corresponding to the width dimension of the upper plate 39 is set so as to gradually decrease from the portion far from the casing pipe 2 to the portion close to the casing pipe 2 in the movable excavating blade 53, and the oblique plate The width dimension H and the angle β of 50 are also set so that the movable excavating blade 53 gradually decreases from a portion far from the casing pipe 2 toward a portion near the casing pipe 2.

  In other words, the amount of fog, which is the degree of the concave shape of the forward blade shape in the cross section of the movable excavation blade 53, gradually decreases from the portion far from the casing pipe 2 to the portion close to the casing pipe 2 in the movable excavation blade 53. It is set as follows.

  Therefore, according to the seventh embodiment, the movable excavation blade 53 itself has a so-called flat plate shape, but the amount of fog gradually decreases from a portion far from the casing pipe 2 toward a portion close to the casing pipe 2. By providing the return plate 28, the same effects as those of the first embodiment described above can be obtained.

  Here, FIG. 1 shows a case where excavation is performed with the excavating blade 3 whose diameter is under the cutting edge of the caisson 1, but of course the excavation blade 3 with the reduced diameter is located above the blade edge of the caisson 1. It is of course possible to excavate the bottom of the hole inside the caisson 1. In other words, excavation blade 3 performs excavation with the diameter of excavation blade 3 reduced in a state where excavation blade 3 is positioned above blade edge 1a of caisson 1, while excavation blade 3 reaches the lower edge of caisson 1 for the first time. While excavating while excavating blade 3 is shifted to the expanded diameter state, it is possible to continue excavation to a predetermined depth while maintaining the expanded diameter state.

  19 to 22 are views showing an eighth embodiment of the present invention. In particular, FIG. 19 shows a reduced diameter state of the excavating blade 3 similar to FIG. 8, and FIG. 21 shows an excavating blade 3 similar to FIG. Each of the expanded diameter states is shown. In these FIGS. 19 to 22, the same reference numerals are given to portions common to the second embodiment shown in FIGS. 10 to 12.

  In this eighth embodiment, as is clear from FIGS. 20 and 22, a single-plate earth and sand return plate 38 bent in a substantially U-shaped cross section is attached to the front surface of the movable excavating blade 13 obliquely upward. In addition, a single-plate earth and sand return plate 48, which is also bent in a substantially U-shaped cross section, is mounted obliquely upward on the front surface of the fixed excavation blade 12. Regardless of whether the excavation blade 3 is in a reduced diameter state or an expanded diameter state, or in a transient state of the diameter expansion operation, the sediment return plate 38 and the fixed excavation blade on the movable excavation blade 13 side. The two sediment return plates 48 and 38 are offset in the overlapping direction of the fixed excavation blade 12 and the movable excavation 13 so that the 12-side sediment return plate 48 does not interfere with each other.

  In other words, in the excavation blade 3 shown in FIGS. 19 to 22, the earth excavation plate 38 is attached to the movable excavation blade 13, and the earth excavation plate 48 is also attached to the fixed excavation blade 13. Therefore, as is apparent from FIGS. 20 and 22, the cross section perpendicular to the longitudinal direction of the entire length of the excavating blade 3 regardless of whether it is in a reduced diameter state or an expanded diameter state. Excavation blade 3 in a shape in which a portion above excavation blade 17 covers the front side in the excavation progress direction with respect to the position of excavation blade 17 whose shape is the excavation point, that is, in a cross section perpendicular to the longitudinal direction of excavation blade 3 The whole is formed as a forward blade shape having a concave shape toward the front side in the excavation direction.

  As is clear from FIGS. 19 and 21, the movable excavating blade 13 has incident angles θ <b> 1 and θ <b> 2 in a plan view as in the second embodiment shown in FIGS. 10 to 12. The shape in which the tip end side far from the casing pipe 2 covers the front side in the excavation progress direction with respect to the base side near the casing pipe 2 in the plan view, that is, at least the movable excavation blade 13 is in the front side in the excavation progress direction in the plan view. It is formed as a forward-facing blade shape that becomes concave toward the top.

  Therefore, according to the eighth embodiment, the same effect as that of the second embodiment shown in FIGS. 10 to 12 can be obtained. In particular, the excavating blade as shown in FIG. 3, the earth and sand return plates 48 and 48 are attached to the fixed excavation blade 12 near the casing pipe 2, so that the earth and sand return plates 38 and 48 are not interrupted in the longitudinal direction of the excavation blade 3. Therefore, the effect of guiding the earth and sand at the portion near the casing pipe 2 and the earth and sand intake port 21 becomes more remarkable.

BRIEF DESCRIPTION OF THE DRAWINGS The whole schematic explanatory drawing which shows preferable 1st Embodiment of the excavation earthing method and diameter expansion excavation apparatus which concern on this invention. The principal part expansion explanatory view of FIG. It is a figure which shows the detail of an excavation blade, and is sectional drawing which follows the AA line of FIG. It is a figure which similarly shows the detail of an excavation blade, and is sectional drawing which follows the BB line of FIG. FIG. 4 is an enlarged explanatory view of a single excavation blade in FIG. 3. It is a figure which shows the detail of the principal part of FIG. 2, (A) is an enlarged view of the front-end | tip of the casing pipe containing a preceding excavation blade, (B) is the plane explanatory drawing. Explanatory drawing which shows the state which diameter-reduced the excavation blade of FIG. Explanatory drawing which similarly shows the state which diameter-reduced the excavation blade of FIG. The principal part explanatory drawing at the time of employ | adopting a reverse system instead of the hammer grab of FIG. 1 as a soil removal means. It is a figure which shows the 2nd Embodiment of this invention, and is expanded explanatory drawing of a single excavation blade. 10A and 10B are cross-sectional views taken along line aa in FIG. 10, FIG. 10B is a cross-sectional view taken along line bb in FIG. 10, and FIG. Sectional drawing which follows the cc line | wire. Explanatory drawing which shows the excavation soil state in the cross section of (C) of FIG. It is a figure which shows the 3rd Embodiment of this invention, and is expanded explanatory drawing of a single excavation blade. It is a figure which shows the 4th Embodiment of this invention, and is expanded explanatory drawing of a single excavation blade. FIG. 9 is a diagram showing a fifth embodiment of the present invention, and an enlarged cross-sectional view corresponding to a cross section taken along line BB in FIG. 2. FIG. 10 is an enlarged cross-sectional view corresponding to a cross section taken along line BB in FIG. 2, showing a sixth embodiment of the present invention. It is a figure which shows the 7th Embodiment of this invention, and is plane explanatory drawing of the casing pipe containing an excavation blade. It is a figure which shows the detail of the excavation blade in FIG. 17, (A) is an expanded sectional view which follows the CC line of FIG. 17, (B) is an expanded sectional view which follows the DD line of FIG. The expanded sectional view which follows the EE line of FIG. It is a figure which shows the 8th Embodiment of this invention, and is plane | planar explanatory drawing in the diameter reduction state of an excavation blade. 19A and 19B are diagrams illustrating cross-sectional shapes of respective portions of the excavating blade illustrated in FIG. 19, in which FIG. 19A is an enlarged cross-sectional view taken along line a <b> 1-a <b> 1 in FIG. (C) is an expanded sectional view which follows the a3-a3 line of FIG. Plane | planar explanatory drawing which shows the diameter expansion state of the excavation blade shown in FIG. FIG. 22A is an enlarged sectional view taken along line b1-b1 in FIG. 21, and FIG. 22B is an enlarged sectional view taken along line b2-b2 in FIG. 21; (C) is an expanded sectional view which follows the b3-b3 line of FIG. 21, (D) is an expanded sectional view which follows the b4-b4 line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Caisson 1a ... Cutting edge 2 ... Casing pipe 3 ... Excavation blade 4 ... Rotation pushing device 5 ... Press-fitting jack as a press-fitting settling device 6 ... Hammer grab as bucket earthing means 9 ... Leading excavation blade 12 ... Fixed excavation blade 13 ... Movable drilling blade 15 ... Hydraulic cylinder (direct acting actuator)
17 ... Drilling blade (drilling point)
DESCRIPTION OF SYMBOLS 18 ... Sediment return plate 19 ... Upper plate 20 ... Slope plate 21 ... Sediment intake port 28 ... Sediment return plate 30 ... Slope plate 33 ... Movable excavation blade 38 ... Sediment return plate 39 ... Upper plate 40 ... Slope shape Plate 43 ... Movable excavator blade 48 ... Sediment reversing plate 50 ... Slanted plate 53 ... Movable excavator blade 60 ... Sand pump (muddy water type soil removal means)
61 ... Drain pipe (muddy water type earth discharging means)
W: Cover amount α: Cover amount θ1, θ2: Incident angle (cover amount)
θ11 to θ14: Incident angle (coverage amount)

Claims (17)

A plurality of excavating blades projecting radially are provided on the outer periphery of the casing pipe that is press-fitted in the vertical downward direction while being rotationally driven, and the casing pipe is further forward in the rotational direction than the intersection with the excavating blade. The earth and sand intake port is opened, and the ground is excavated with at least the lower end of the excavating blade as the excavation point by rotating the casing pipe together with the excavating blade, and at least a part of the excavated earth and sand is along the excavating blade It is a method of guiding and discharging soil into the casing pipe through the soil intake port,
The excavation blade has a shape in which a portion above the excavation point covers the front side in the rotation direction with respect to the excavation point in a cross section orthogonal to the projection direction of the excavation blade itself, and is orthogonal to the projection direction of the excavation blade itself The surface on the front side in the rotational direction has a concave shape in the cross section
A method for excavating and discharging soil characterized in that the earth and sand excavated by the excavating blade is guided forward in the rotational direction of the excavating blade and above the excavation point, taken into a casing pipe, and discharged. The excavation blade has a shape in which the tip end side far from the casing pipe covers the front side in the rotation direction with respect to the base side near the casing pipe in a plan view,
The earth and sand excavated by the excavating blade is guided forward in the rotation direction of the excavating blade and upward from the excavation point, and is guided in the direction of the earth and sand intake to be taken into the casing pipe and discharged. The excavation and earthing method according to claim 1 . The excavation and earthing method according to claim 2, wherein the excavation blade has a concave shape on the front side in the rotational direction in plan view. The excavator blade is formed by a fixed excavator blade and a movable excavator blade that can move parallel to the fixed excavator blade so that the excavator blade can be expanded and contracted. The excavation and earthing method according to any one of claims 1 to 3, wherein the excavation and earthing method can be expanded and contracted according to a diameter. The movable excavator blade has a shape having an incident angle of one or more stages so that the tip end side far from the casing pipe is covered in a stepwise manner toward the front side in the rotation direction with respect to the root side near the casing pipe in plan view, 5. The excavation exhaust according to claim 4, wherein the plane of the movable excavation blade itself has a curved shape curved so that the surface on the front side in the rotational direction in the plan view has a concave shape. Earth method. Drilling a preceding drilling hole that is larger than the casing pipe diameter and smaller than the minimum drilling diameter that can be drilled by the drilling blade, and the earth and sand excavated by the drilling blade precedes the gap between the casing pipe and the preceding drilling hole. The excavation and earthing method according to any one of claims 1 to 5, wherein the earth is taken into and excavated into the excavation hole. The excavation and soil removal method according to any one of claims 1 to 6, wherein bucket-type soil removal means is used as means for discharging the earth and sand taken into the casing. The excavation and soil discharging method according to any one of claims 1 to 6, wherein muddy water type soil discharging means is used as means for discharging the earth and sand taken into the casing. A method for press-fitting caisson with the excavation and earthing method according to claim 4 or 5 ,
A trajectory drawn by rotation of the tip of a movable excavating blade that forms a part of the excavating blade by extending the excavating airfoil after the contracted excavating blade is positioned below the blade tip of the caisson. Expanding the diameter; and
Drilling the caisson under the cutting edge with a drilling diameter larger than at least the inner diameter of the caisson with the drilling blade in the expanded state;
A step of press-fitting caisson after diameter expansion excavation under the cutting edge;
A caisson press-fitting method characterized by comprising: A plurality of excavating blades projecting radially are provided on the outer periphery of the casing pipe that is press-fitted in the vertical downward direction while being rotationally driven, and the casing pipe is further forward in the rotational direction than the intersection with the excavating blade. The earth and sand intake opening is formed, and the ground pipe is excavated with at least the lower end of the excavating wing as an excavation point by rotating the casing pipe together with the excavating blade, and at least a part of the excavated earth and sand is removed from the earth and sand intake opening to the casing pipe. A drilling rig adapted to be incorporated in the interior,
The excavator blade is formed by a fixed excavator blade and a movable excavator blade that can move parallel to the fixed excavator blade so that the excavator blade can be expanded and contracted. While configured to be able to expand and contract according to the diameter,
At least the movable excavator blade has a shape in which a portion above the excavation point covers the front side in the rotational direction with respect to the excavation point in a cross section perpendicular to the moving direction of the fixed excavation blade, and the fixed excavation blade The diameter-expanded excavator is characterized in that the surface on the front side in the rotational direction has a concave shape in a cross section orthogonal to the moving direction of itself with respect to . 11. The diameter-extended excavator according to claim 10, wherein the fixed excavation blade, together with the movable excavation blade, has a concave surface on the front side in the rotational direction in a cross section orthogonal to the longitudinal direction of the fixed excavation blade. In place of the movable excavation blade according to claim 10 or 11 ,
The movable excavating blade has a shape in which the tip end side far from the casing pipe covers the front side in the rotational direction with respect to the base portion side close to the casing pipe in plan view, and is orthogonal to the moving direction of the fixed excavating blade itself. The diameter expansion excavator characterized in that the front surface in the rotational direction has a concave shape in the cross section. The diameter-extended excavator according to claim 12, wherein the movable excavating blade has a concave shape on the front side in the rotational direction in plan view. Whether the movable excavating blade has a shape having an incident angle of one or more stages so that the tip end side far from the casing pipe is covered stepwise toward the front side in the excavation traveling direction with respect to the base portion side close to the casing pipe in a plan view. or by a movable drill blades curved with a plan view shape of the curve itself shape, according to claim 12 or 13, characterized in that the surface of the rotating direction of the front side has a concave shape in a plan view Diameter drilling rig. In the cross section perpendicular to the moving direction of the movable excavating blade with respect to the fixed excavating blade, the amount of cover that is the degree of the shape in which the upper part of the movable excavating point covers the front side in the rotational direction with respect to the excavating point of the movable excavating blade is movable The diameter-expanded excavator according to claim 10, wherein the diameter of the excavating blade is set so as to gradually decrease from a distal end side far from the casing pipe toward a root portion near the casing pipe. The diameter expansion excavation device according to any one of claims 10 to 15, wherein the casing pipe is provided with a plurality of excavation blades oriented in a tangential direction of the casing pipe in a plan view at an equal pitch. A preceding excavation blade for excavating a preceding excavation hole having a diameter larger than the casing pipe diameter and smaller than a minimum excavation diameter that can be excavated by the excavation blade is provided at a position below the excavation blade in the casing pipe. The diameter expansion excavator according to any one of claims 10 to 16 .

Images