JP2016217121A - Ground reinforcement casing and ground reinforcement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make construction easy, since the number of columnar pile is reduced, when bearing power of the columnar pile can be further increased, though a ground reinforcement technique for establishing the columnar pile by a non-earth removal system is conventionally known.SOLUTION: A ground improvement casing comprises a cylindrical casing body 3 and an overhang part 63 arranged on the base end side of the casing body and forming an external shape of overhanging to the outside in the radial direction of the casing body, and the overhang part is constituted of the same diameter enlarged diameter part 65 for enlarging a diameter in the same diameter shape and an inclined diameter reduction part 67 linked on the base end side to the same diameter enlarged diameter part and reducing a diameter in an inclined shape toward the hole drilling direction. The periphery of the established columnar pile becomes a consolidation wall, and peripheral surface frictional force is secured. A part having the overhang part 63 becomes a diameter-enlarged pile head, and since its undersurface side is inclined, the consolidation wall is also formed on its periphery, and the peripheral surface frictional force is secured. Thus, ground bearing power is secured by the presence of a pile head.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a ground reinforcing casing used for a ground reinforcing method for reinforcing a ground by creating a pile in the ground by solidifying a solidifying material such as cement milk, and a ground reinforcing method using the ground reinforcing casing. It is.

  Conventionally, as a method of reinforcing a soft ground, there is known a method in which a solidified material such as cement milk is injected into the ground, and a columnar pile is formed by the solidification, but recently, as described in Patent Document 1 In addition, the frictional force of the peripheral surface is used to strengthen the support force of the pile, and in order to make the soil free from industrial waste, the soil around the hole edge is not discharged without discharging the soil that is generated when drilling. It has been proposed to push the ground toward the ground and consolidate.

JP-A-10-280381

  If the supporting force of the pile can be further strengthened, the number of piles can be reduced, and the work at the time of creation and disposal becomes easier, but if the peripheral surface friction force is increased by increasing the peripheral area, Although the drilling capability will be increased by making the spiral blade of the casing larger, there is a limit because it assumes no soil removal.

  Therefore, an object of the present invention is to provide a ground reinforcing casing having a structure devised based on a novel viewpoint.

  The present invention was made to achieve the above object, and the invention of claim 1 is a ground reinforcement method for reinforcing the ground by creating a columnar pile from solidification of the solidified material injected into the ground. A ground reinforcing casing used for consolidation of a drilling hole and the hole edge, and a cylindrical casing body having an axial direction as a drilling direction, and fitted to the casing body, and radially outward of the casing body A projecting portion that forms an outer shape that projects to the same diameter, and the projecting portion is connected to the same diameter-enlarged portion that is expanded to the same diameter, and is connected to the same-diameter expanded portion on the front side in the drilling direction. And an inclined diameter-reducing portion that is reduced in diameter toward the direction, and is configured to be slidable in the axial direction with respect to the casing body and appropriately fixed at a predetermined position. It is a casing for ground reinforcement characterized by the above.

  According to a second aspect of the present invention, in the ground reinforcing casing according to the first aspect, the fixing means for fixing the overhanging portion to the casing body so as to be immovable in the axial direction and around the axis is provided after the boring direction of the overhanging portion. It is formed across the boundary between the inner peripheral surface of the fixing cylinder portion provided continuously on the side and the outer peripheral surface of the casing body, and is composed of an insertion hole penetrating perpendicularly to the drilling direction, and a separate insertion shaft, The ground reinforcing casing is fixed when the insertion shaft is inserted into the insertion hole.

  According to a third aspect of the present invention, in the ground reinforcing casing according to the second aspect, the concave portion on the casing body side constituting the insertion hole is formed in a thicker portion than the others. It is a casing.

  According to a fourth aspect of the present invention, in the ground reinforcing casing according to any one of the first to third aspects, the overhanging portion is formed of a casting.

  According to a fifth aspect of the present invention, in the ground reinforcing casing according to any one of the first to fourth aspects, the distal end portion of the casing body has a tubular tapered portion whose diameter is reduced in an inclined manner toward the drilling direction, and the cutting portion thereof. The ground reinforcing casing includes a solid bit portion continuously provided on the front side in the hole direction, and a discharge hole is provided in the tubular tapered portion.

  According to a sixth aspect of the present invention, in the ground reinforcing casing according to any one of the first to fourth aspects, the front end portion of the casing body rotates with the forward rotation when the drilling proceeds, and the negative portion when the reverse pulling-back is performed. In the rotation, the casing is divided from the casing body, and a slurry-like solidified material is discharged from the dividing port.

  A seventh aspect of the present invention is a ground reinforcement method using the ground reinforcing casing according to any one of the first to sixth aspects, wherein the ground reinforcing casing is used to drill a hole, and a solidified material is injected into the hole. Then, before the solidified material is completely solidified, the ground reinforcing method is characterized in that the solidified material is inserted so as to be coaxial with the columnar pile forming the bending reinforcing steel pipe.

  The invention according to claim 8 is a steel tube for bending reinforcement used in the ground reinforcement method according to claim 7, wherein the top end adjustment cap is closed on the axial top side, and the top end adjustment cap includes The steel pipe for bending reinforcement is characterized in that a top end reference surface whose diameter is increased radially outward and an air port that penetrates the top end reference surface and communicates with the inside of the pipe are provided.

  If the ground reinforcement casing of the present invention is used, the supporting force of the columnar piles created can be further increased by the same operation as before.

It is a perspective view of the casing for ground reinforcement concerning the 1st embodiment of the present invention. It is a perspective view of the overhang | projection part with which the ground reinforcement casing of FIG. 1 was equipped. FIG. 3 is a cross-sectional view of FIG. 2. It is explanatory drawing of the up-and-down movement of the overhang | projection part of FIG. It is a perspective view of the front-end | tip part with which the ground reinforcement casing of FIG. 1 was equipped. It is sectional drawing of FIG. It is explanatory drawing of the construction method of the columnar pile which uses the casing for ground reinforcement of FIG. FIG. 8 is an explanatory diagram following FIG. 7. It is explanatory drawing following FIG. FIG. 10 is an explanatory diagram following FIG. 9. It is explanatory drawing of the support state in the head of the columnar pile created in FIG. It is a side view by the side of the overhang | projection part of the ground reinforcement casing which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the ground reinforcement casing of FIG. It is a disassembled perspective view of FIG. It is a top view which shows the assembly state of FIG. It is a whole side view of the ground reinforcement casing which concerns on the 3rd Embodiment of this invention. It is a partial cross section side view of the casing main body of the ground reinforcement casing of FIG. It is a partial cross section side view of the overhang | projection part of the ground reinforcement casing of FIG. It is a partial cross section side view of the fixed state of the overhang | projection part in the ground reinforcement casing of FIG. It is explanatory drawing of the construction method of the columnar pile which uses the casing for ground reinforcement of FIG. It is a side view of the steel pipe for bending reinforcement used for a ground reinforcement construction method with a ground reinforcement casing. It is explanatory drawing of the construction method of the columnar pile at the time of using the steel pipe for bending reinforcement of FIG.

A ground reinforcing casing 1 according to a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the ground reinforcing casing 1 is provided with a long cylindrical casing body 3. Both ends of the casing main body 3 are open, the upper side is the base end side, and the lower side is the drilling side, and a helical screw blade 5 is attached to the outer peripheral surface of the drilling side.
An overhang portion 7 is disposed on the casing body 3.

  The overhanging portion 7 has a substantially cylindrical shape, and the upper side is a cylindrical portion 9 having the same diameter, and the lower end thereof has an inverted conical cylindrical portion 11 that is reduced in diameter so as to be narrowed downward. Are connected without steps. The cylinder length is relatively short in the upper-side same-diameter cylinder part 9, but the lower inclined cylinder part 11 extends long at a gentle inclination angle. In addition, a short connecting cylinder portion 15 is connected to the lower end of the lower inclined cylinder portion 11 via a stepped portion 13, and the connecting cylinder portion 15 has the same diameter. The connecting cylinder portion 15 is smaller in diameter than the lower inclined cylinder portion 11 by the stepped portion 13 (see FIG. 3).

As shown in FIGS. 2 and 3, the projecting tube portion 9, 11 to 11, the connecting tube portion 15 are formed into a cylindrical shape by abutting a pair of half-divided members 17, 17 curved in a semicircular arc shape. Has been produced.
In each half-shaped member 17, mating pieces 19, 19 are connected to both edges on the molding side of the projecting tubular portions 9, 11. The mating piece 19 is formed by bending the edge side, and projects from the upper end of the upper same-diameter cylindrical portion 9 to near the lower end of the lower inclined cylindrical portion 11 so as to project short toward the radial center in the cylinder. doing.
In addition, a mating piece 21 is also connected to the edge of the connecting cylinder portion 15 on the molding side. The mating piece 21 is also formed by bending the edge side, but projects short in the radial direction outside the cylinder.

The above-mentioned matching piece 19 is provided with a bolt insertion hole, and the matching piece 19 on the one half-shaped member 17 side and the matching piece 19 on the other half-shaped member 17 side are overlapped, respectively. When tightened at 23, as described above, the pair of halved members 17, 17 are abutted to form the projecting portion 7 in a cylindrical shape.
Further, the above-mentioned mating piece 21 is provided with a bolt insertion hole. When one mating piece 21 and the other mating piece 21 are overlapped and tightened with a bolt 23, a connecting cylinder is formed as described above. Part 15 is molded.
In FIG. 2, in order to easily identify the half-shaped members 17 and 17, one is denoted as 17 </ b> A and the other is denoted as 17 </ b> B, and its constituent parts are also distinguished from A and B.

  The overhanging portion 7 (the upper same diameter cylindrical portion 9 and the lower inclined cylindrical portion 11) to the connecting cylindrical portion 15 are formed by joining the half-divided members 17 and 17 with the above-described casing body 3 sandwiched between them and tightening them with bolts. And is externally fitted to the casing body 3. Accordingly, the projecting portion 7 has an outer shape projecting radially outward with respect to the casing body 3. When viewed from the outside, the upper same-diameter cylindrical portion 9 has the same-diameter enlarged portion and the lower inclined cylindrical portion 11. Is an inclined diameter-reduced portion.

Reference numeral 25 denotes a stopper fitting, which is composed of a pair of half-shaped fittings 27. Each half-shaped bracket 27 is formed by bending a thin strip-shaped material, the middle is curved in a semicircular shape to form a holding portion 29, and both end sides thereof are bent radially outward, A pair of mating pieces 31, 31 is formed. The mating piece 31 is provided with a bolt insertion hole. When the mating pieces 31 and 31 of the pair of half-shaped brackets 27 and 27 are overlapped with each other and tightened with the bolt 33, the holding portions 29 and 29 are provided. The inner peripheral surface is connected in an annular shape to form a stopper fitting 25.
In FIG. 2, in order to easily identify the half-shaped brackets 27, 27, one is represented as 27 </ b> A and the other is represented as 27 </ b> B, and the components are also distinguished from A and B.

In FIG. 3, reference numeral 35 denotes an O-ring.
The O-ring 35 is externally fitted to the casing main body 3 in an elastically compressed state, and the pair of half-shaped metal fittings 27 and 27 are inserted into the casing main body via the O-ring 35 at the respective holding portions 29 and 29. When the mating pieces 31, 31 are overlapped and bolted while holding 3, the casing main body 3 can be firmly attached.
Since the above-described overhanging portion 7 is slidable when fitted over the casing body 3, the stopper fitting 25 and the O-ring 35 are attached to the non-slidable and non-rotatable shaft. Two stopper fittings 25 are attached to the casing body 3 via O-rings 35 so as to sandwich the cylindrical overhanging portion 7 from above and below. The lower stopper fitting 25 is pressed from the lower side against the cylinder edge of the connecting cylinder portion 15, and the upper stopper fitting 25 enters the lower inclined cylinder portion 11 of the overhanging portion 7 and enters the stepped portion 13. It is being pressed.

With the above configuration, as shown in FIG. 4, the overhang portion 7 can be stably attached to an arbitrary position of the casing body 3.
In FIG. 4 (1), the overhang portion 7 is attached to the upper end side of the casing body 3. 4 (2) is a lower position than FIG. 4 (1), and the overhanging portion 7 is attached to the casing body 3. FIG. In this way, the mounting position can be adjusted according to the depth of the columnar pile, and there is no need to prepare a plurality of casings for each depth.
Moreover, since the overhang | projection part 7 and the stopper metal fitting 25 are comprised in the shape of a half, the troublesome thing which passes along the elongate casing main body 3 is not required for field work.
Although not shown, reinforcing ribs are attached to the inner peripheral surface of the half-shaped member 17 so as to extend in the vertical direction as protrusions, and sufficient strength is ensured.

Next, the front end side of the drilling hole will be described.
As shown in FIG. 1, a feed pipe 37 is coaxially inserted inside the casing body 3 to form a so-called double pipe structure. The feeding pipe 37 is for feeding a solidified material such as cement milk to be injected into the ground after drilling. As shown in FIG. 5, the tip side of the drilling hole, that is, the lower end side in the figure is a casing. It extends downward from the lower end of the main body 3, and its lower end is opened to form a discharge port 39.
A push block 41 protrudes from the outer peripheral surface of the extended lower end portion. The push block 41 has a substantially rectangular shape and is elongated in the vertical direction side, but the outer peripheral surface has an arc shape when viewed from the axial cross section side. Two push blocks 41 are arranged in a state of being opposed to each other in the diametrical direction with the feeding pipe 37 interposed therebetween.

A separate distal end portion 43 is disposed on the distal end side of the casing body 3 in the drilling direction. The tip portion 43 is made of a casting, and a bit portion 47 whose tip is sharpened conically is connected to a cylindrical connecting portion 45 having the same diameter. The connection part 45 side is hollow, and the connection side with the casing body 3 is open.
A pair of receiving blocks 49, 49 are fitted and fixed to the inner peripheral surface side of the connecting portion 45, and project from the center side. Each receiving block 49 is similar to the inner peripheral surface of the connecting portion 45, and the axial cross-section side is formed in an arc shape on both the outer peripheral side and the inner peripheral side, and the upper half 51 is slightly larger than the quarter arc. However, the lower half portion 53 is cut out to be 1/3 or less of the upper half portion 51, and has an inverted L shape as a whole.

Inside the connecting portion 45, a pair of receiving blocks 49, 49 are arranged rotationally symmetrically with respect to the axial center, and the axial central portion is open in the vertical direction. In addition, a gap is formed between the receiving block 49 and the receiving block 49 in the peripheral portion.
Therefore, as shown by the arrow in FIG. 5, the axial center portion of the connecting portion 45 is coaxially aligned with the feed pipe 37 and the clearance between the receiving blocks 49 and 49 is relative to the push block 41. Accordingly, when the distal end portion 43 is brought closer to the feed pipe 37, the push blocks 41 and 41 pass through the gap, and the feed pipe 37 enters deeply into the axial center portion of the connecting portion 45.

In this state, as shown in FIG. 6, when the feed pipe 37 rotates about its axis, the lower half 53 of the receiving block 49 on the distal end 43 side is moved along the movement path of the push block 41 on the feed pipe 37 side. Is located.
When the casing body 3 is drilled, the feed pipe 37 rotates about the axis in the forward direction as shown by the arrow, and the push block 41 pushes the receiving surface 55 of the lower half 53 of the tip end portion 43. The part 43 rotates with the feed pipe 37.
On the other hand, when the feed pipe 37 moves backward together with the casing body 3 for pulling out, it rotates about the axis in the negative direction as shown by the arrow, the push block 41 is separated from the receiving surface 55, and the upper half 51 is also missing. To the gap. Since this gap portion is wide enough for the push block 41 to pass through, the push block 41 passes through this gap portion, and the feed pipe 37 is pulled up with the tip portion 43 remaining.

The ground reinforcing casing 1 includes the above-described characteristic configuration on both ends in the axial direction.
This ground reinforcing casing 1 works in the same manner as a conventional columnar pile construction type.
That is, as shown in FIG. 7, the ground 1 is drilled by excavating the casing 1 (casing body 3 + tip portion 43) to a predetermined depth while rotating it forward. When reaching a predetermined depth, as shown in FIG. 8, the overhanging portion 7 is just completely buried.

Thereafter, as shown in FIG. 9, the solidified material S such as cement milk is discharged from the discharge port 39, negatively rotated, the tip end portion 43 is divided, and only the casing body 3 is pulled up.
In parallel with the above pulling, the solidified material S is sequentially injected and filled in the hollow of the front end portion 43 and its periphery, and further in the hole, and the hole is filled as shown in FIG. When this is solidified, the columnar pile K has been created.
Since the solidified material S is discharged downward from the discharge port 39, the surrounding ground is not disturbed.

As shown in FIG. 11, the circumference of the formed columnar pile K is a compacted wall (P), and as shown by the arrow, a peripheral friction force (a) is secured around the pile shaft (K1). Therefore, a sufficient pile axial direction supporting force (A) is ensured.
Moreover, the part with the overhang | projection part 7 is the pile head (K2) expanded in diameter. The enlarged view corresponds to a part of the enlarged view, but for the sake of visual recognition, the inclined portion is deformed with a large inclination angle.
As shown in this enlarged view, the pile head (K2) extends radially outward from the pile axis (K1). Since the lower surface side of the pile head (K2) is inclined, a compaction wall P is also formed around the pile head (K2), and a circumferential frictional force (b) is ensured. Therefore, even around the axis (K1) of the columnar pile K, the pile head (K2) acts directly on the foundation to secure the ground support force (B).

As described above, if the ground reinforcing casing 1 is used, a composite supporting force can be ensured even with the same shaft thickness as the conventional one, so that the supporting force can be further increased.
Since the supporting force per columnar pile has increased, if the same supporting force as before is sufficient, the number of columnar piles can be reduced by increasing the pile formation interval. Moreover, it is also possible to shorten the axial length of a columnar pile compared with the past, and it is advantageous also from this surface.
The ground supporting force depends on the shape of the overhanging portion 7 and can be adjusted by changing the tube length and the tube diameter of the upper same-diameter cylindrical portion 9 and further the setting condition of the inclination angle of the lower inclined cylindrical portion 11. , Can respond to the ground separately.

A ground reinforcing casing 61 according to a second embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 12 and 13, the ground reinforcing casing 61 is also provided with a long cylindrical casing body 3. An overhang portion 63 is disposed on the base end side of the casing body 3.

The overhang portion 63 has a substantially cylindrical shape. The upper portion is a large cylindrical portion 65 having the same diameter, and an inverted conical cylindrical portion 67 whose diameter is reduced so that the middle is narrowed downward. The cylindrical portion 69 has a small diameter, and is continuous and integrated with no step. The intermediate inclined cylinder portion 67 has an inclination angle of 30 °.
The overhang portion 63 is fitted on the casing body 3. Accordingly, the projecting portion 63 has an outer shape projecting radially outward with respect to the casing body 3. When viewed from the outside, the upper same-diameter cylindrical portion 65 has the same-diameter enlarged portion and the intermediate inclined cylindrical portion 67. It is an inclined reduced diameter part.

  As shown in FIG. 14, the overhang portion 63 opens in the vertical direction, but a pair of mating portions 71 and 71 are provided at the upper end. The mating portion 71 is composed of a ¼ arc plate on the outer peripheral side and the inner peripheral side, and a lower piece 73 is continuously provided on the inner peripheral side by being bent downward. The mating portions 71 and 71 are arranged in a state of facing the axis center, and the inner peripheral sides are opposed to each other with an interval. The mating portion 71 is provided with an insertion hole 72 </ b> A for the pin 75.

Reference numeral 77 denotes a half-shaped lifting prevention metal fitting. The lifting prevention metal fitting 77 has the same plate shape as the mating portion 71 described above, and is further provided with a pin 75 insertion hole 72B. A wall portion 79 rises from the inner peripheral edge of the lifting prevention metal fitting 77. One side of the wall portion 79 extends beyond the plate surface of the metal fitting, has an arc shape when viewed from above, and is smaller than the semicircular arc. Both end sides of the wall portion 79 are bent and become attachment portions 81. The attachment portion 81 is provided with an insertion hole 82 for a bolt 83.
Two lifting prevention metal fittings 77 are prepared. As shown in FIG. 15, the lifting prevention metal fittings 77 are superimposed on the mating portions 71 of the overhang portions 63 from above, and the insertion holes 72A and 72B communicate with each other in the vertical direction. A pin 75 is inserted into the insertion hole from above, and the lifting prevention metal fittings 77 and 77 are fixed to the overhanging portion 63 to prevent the lifting.

In this state, the wall portions 79 are connected in a ring shape, and the casing body 3 passes through the walls 79 and 79.
Then, the mounting portion 81 of one lifting prevention metal fitting 77 is opposed to the mounting portion 81 on the extension side of the other lifting prevention metal fitting 77, and the mounting portion 81 of the one lifting prevention metal fitting 77 is the other lifting prevention metal. It faces the mounting portion 81 on the extension side of the metal fitting 77.
A rubber packing 85 is interposed between the casing body 3 and the casing body 3.
The mounting portions 81 and 81 facing each other are overlapped with each other, a bolt 83 is passed through the insertion hole and fastened with a bolt and nut, and the lifting prevention metal fittings 77 and 77 are firmly fixed to the casing body 3. By this fixing, the overhanging portion 63 is attached to the casing body 3.

A rubber packing 87 is also interposed between the lower cylinder portion 69 and the casing main body 3, and rubber packing 85 and 87 are interposed at the upper and lower sides so that dirt or the like flows into the gap with the casing main body 3. It is blocked.
With the above configuration, the overhang portion 63 can be stably attached to an arbitrary position on the base end side of the casing body 3.
This overhanging portion 63 can provide the same effects as the overhanging portion 7 according to the first embodiment. Furthermore, although the overhang | projection part 63 is integral from the beginning and needs to pass through the casing main body 3, the assembly operation itself in the field is easy.

  A feeding pipe 37 is coaxially inserted inside the casing main body 3 to form a so-called double pipe structure, but the feeding pipe 37 protrudes from the upper end of the casing main body 3. The opening of the upper end of the casing body 3 is narrowed by an inward flange 89, and a connecting piece 91 is attached to the outer periphery of the part that has come out. The connecting piece 91 is fixed to the inner flange 89 of the casing body 3 so that the feed pipe 37 cannot move with respect to the casing body 3.

A ground reinforcing casing 93 according to a third embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 16, the ground reinforcing casing 93 is similarly provided with a long cylindrical casing body 95.
A short fixing cylinder 97 is inserted in the casing main body 95 in the middle and integrated by welding. As shown in the partial cross-sectional side view of FIG. 17, the outer diameter of the fixing cylinder portion 97 is continuous without a step, but the fixing cylinder portion 97 is thick, and the inner diameter is reduced accordingly. It has become.

  As shown in the cross-sectional view taken along the AA arrow, the outer peripheral surface side of the fixing cylindrical portion 97 is notched in a straight line perpendicular to the axial direction of the casing body 95, in other words, the drilling direction, and reaches both ends. This notched portion is a groove-like concave strip 99 that is recessed in a circular arc shape on the axial center side. Therefore, the concave wall of the concave strip portion 99 is the highest in the middle of the shaft center and is lowered toward both ends. A pair of concave strips 99 are provided and are opposed to each other across the axis center.

Further, a push-up pipe 101 is externally fitted to the front side in the drilling direction from the fixing cylinder portion 97 and integrated by welding. The screw blade 5 is disposed on the front side in the drilling direction with respect to the push-up pipe 101.
A short discharge cylinder portion 103 is connected to the front side in the drilling direction from the screw blade 5 and integrated by welding. The discharge cylinder portion 103 is subjected to a drawing process and has a diameter reduced in an inclined shape, and is tapered in a tapered shape toward the tip side. A pair of discharge holes 105 are formed in the discharge cylinder portion 103. The discharge holes 105 are opposed to each other across the axis center. In the figure, only one is shown because of the positional relationship.
A separate bit portion 107 is disposed on the short mouth side of the discharge cylinder portion 103, that is, on the front side in the drilling direction. The bit portion 107 is made of cast metal and has a tip sharpened in a conical shape. The bit portion 107 is welded and integrated with the discharge cylinder portion 103.

An overhang portion 109 is disposed on the casing body 95.
As shown in the partial cross-sectional side view of FIG. 18, the overhanging portion 109 has a substantially cylindrical shape. The middle part is a cylindrical part 111 having the same diameter, and an inverted conical cylindrical part 113 whose diameter is reduced in an inclined shape so as to be constricted downward is continuously provided at the lower end thereof without a step. The cylinder length is relatively short in the upper same-diameter cylindrical portion 111, but the lower inclined cylindrical portion 113 extends long at a gentle inclination angle.
A protective cylinder 115 is connected to the lower end of the lower inclined cylinder 113 without a step. The protective cylinder portion 115 has the same diameter and is short.

On the other hand, a fixing cylinder portion 117 having the same diameter is also connected to the upper end of the upper same diameter cylinder portion 111. The outer diameter of the fixing cylindrical portion 117 is smaller than the outer diameter of the upper same-diameter cylindrical portion 111. The fixing cylinder part 117 has a curved surface 119 whose outer peripheral surface is concaved inwardly on the side where it is connected to the upper same diameter cylinder part 111, and transitions to the upper same diameter cylinder part 111 without a step.
The overhanging portion 109 (fixing cylindrical portion 117 to upper same-diameter cylindrical portion 111 to lower inclined cylindrical portion 113 to protective cylindrical portion 115) is integrally formed of an aluminum-based casting and is axially formed on the inner side. An insertion hole 121 having the same diameter passes therethrough.

The overhanging portion 109 is slidably fitted to the casing body 95, and the protective cylinder portion 115 side is the drilling direction front side.
When the inner peripheral surface of the fixing tube portion 117 on the overhanging portion 109 side faces the outer peripheral surface of the fixing tube portion 97 on the casing body 95 side, a pair of insertion holes 123 and 123 (FIG. 19) are formed. It is like that.

The fixing cylinder part 117 is penetrated perpendicularly to the axial direction, in other words, the drilling direction, but as shown in the cross-sectional view taken along the arrow BB, the fixing cylinder part 117 is inserted into the tube wall from the outer peripheral surface of the fixing cylinder part 117. After entering the tube wall and entering the tube wall again, the tube tube 117 is pulled out from the outer surface. Therefore, the through-holes 125, 125 are formed in a straight line in the tube wall, and a concave strip 127 that is recessed on the cross-sectional arc is formed between them.
When the concave portion 127 faces the concave portion 99 on the casing body 95 side, it becomes a hole having a circular cross section, and the through holes 125 and 125 on both sides in the axial direction are connected to form one insertion hole 123.

As shown in FIG. 19, the overhanging portion 109 is slid with respect to the casing main body 93 and brought to a predetermined fixed position. That is, the fixing cylinder part 97 on the casing body 95 side and the fixing cylinder part 117 on the overhanging part 109 side are opposed to each other, and the concave line part 99 and the concave line part 127 are opposed to each other. A hollow portion having a circular cross section is formed by the concave stripe portion 99 and the concave stripe portion 127, and through holes 125 and 125 are connected to both ends of the hollow portion to form a straight insertion hole 123.
When the pin shaft 129 is inserted into the insertion hole 123, the overhanging portion 109 is fixed to the casing body 95 so as not to move in the axial direction and around the axis.

Even when the ground reinforcing casing 93 is used, the operation is performed in the same manner as in the first embodiment.
As shown in FIG. 20A, with the overhanging portion 109 fixed, the axial direction of the casing body 95 is set to the drilling direction of the ground G, and the ground G is dug to a predetermined depth while rotating forward. Drill a hole. 20B, assuming that the overhanging portion 109 has been buried to a predetermined depth, the pin shaft 129 can be removed from the insertion hole 123, and the casing body 95 can be slid with respect to the overhanging portion 109. State.

  Then, as shown in FIG. 20 (C), further excavation is performed, and as shown in FIG. 20 (D), the bit part 107 at the end of the casing body 95 is reached to a predetermined depth, and excavation work is performed. finish. During the excavation, the casing main body 95 is lowered while sliding with respect to the overhanging portion 109, and the overhanging portion 109 is left as it is.

  Thereafter, as shown in FIGS. 20E to 20F, the solidification material S such as cement milk is discharged from the discharge hole 105 while negatively rotating, and the casing body 95 is pulled up. The discharge cylinder 103 has a tapered shape and a gap is formed between the hole edge formed by drilling, and the solidified material S is discharged there, so that the surrounding ground is not disturbed. Absent.

At the position shown in FIG. 20 (F), the push-up pipe 101 on the casing body 95 side hits the protective cylinder part 115 on the overhanging part 109 side. Push up.
Accordingly, as shown in FIG. 20 (G), the overhanging portion 109 together with the casing body 95 is pulled out of the ground G, and the solidified material S is injected and filled in the entire drilling hole including the space where the overhanging portion 109 stays. Is done.
When this is solidified, as shown in FIG. 20 (H), the columnar pile K is formed as in the first embodiment.

Since the overhanging portion 109 is made of a casting, unlike the overhanging portion 7 of the first embodiment, there is no need to assemble at the site. Moreover, because it is made of aluminum, it is sufficient in strength.
Further, as a shape contrivance, the push-up tube 101 does not directly contact the lower inclined cylindrical portion 113 but hits the protective cylindrical portion 115, so that a load applied to the lower inclined cylindrical portion 113 at the time of pulling is increased. It is running low.
Further, the fixing cylinder portion 117 on the casing body 95 side is provided with an upper same-diameter cylindrical portion 111 that is continuously provided in order to reduce the overall weight of the overhang portion 109 and shorten the axial length of the pin shaft 129. Since it has a smaller diameter and a vertical step is formed if it is continuously provided as it is, cracks are easily formed when a load is applied to the corner of the step. However, the curved surface 119 provides a countermeasure against cracks.

  Further, the tip portion is not retained on the ground G, and is pulled up and collected together with the casing body 95, so that it can be used repeatedly. In addition, the discharge cylinder 103 is formed by constricting the casing main body 95, and a bit portion 107 of a simple casting is integrally welded to the tip of the discharge cylinder 103 to constitute a tip portion. The production itself is also easy.

Next, an example in which a bending reinforcing steel pipe 131 is used will be described.
The columnar pile described above is designed to withstand the load applied in the downward direction, and is mainly assumed to be applied to wooden buildings.
On the other hand, for steel-frame buildings, there are many structures in which the pile side and the foundation side are rigidly joined, and not only the load described above but also the force to bend the column is transmitted to the foundation. . For this reason, the use of steel pipe piles is the mainstream on the pile side.
Therefore, since the steel pipe 131 for bending reinforcement can be easily inserted in the above-mentioned columnar pile, the advantage as the columnar pile can be used as it is as a substitute for the steel tube pile. It is considered that the foundation work of the scale for buildings can have the same strength as the conventional rigid joint.

As shown in FIG. 21, the bending-reinforcing steel pipe 131 includes a straight steel pipe 133 whose both ends in the axial direction are open. A top end adjustment cap 135 is attached to one end side in the axial direction of the steel pipe main body 133.
A circular top plate 139 is attached to and closed on one axial end (upper end in the figure) of the fitting cylinder portion 137 of the top end adjustment cap 135. The top plate 139 has a diameter that is larger outward in the radial direction than the fitting tube portion 137, and the top surface is the top end reference surface 140. An air hole 141 is formed in the center of the top plate 139 so as to penetrate in the thickness direction.
The fitting cylinder portion 137 of the top end adjustment cap 135 is fitted and integrated with the steel pipe 133, and the inside of the pipe communicates with the outside of the pipe through the air hole 141 on the upper end side.

An example in which the above-described bending reinforcing steel pipe 131 is integrated by inserting it into a columnar pile K formed using a ground reinforcing casing 93 (third embodiment) is shown in FIG.
Up to FIG. 20 (G), the same operation is performed, and the overhanging portion 109 is pulled out from the ground G together with the casing body 95, and the solidified material S is applied to the entire drilling hole including the space where the overhanging portion 109 stays. Filled and filled. This state corresponds to FIG. 22A in FIG.
Thereafter, as shown in FIGS. 22B and 22C, the bending reinforcing steel pipe 131 is inserted. Since the solidifying material S is a liquid material such as cement milk and does not contain soil or the like, this insertion operation can be easily performed. Since the air in the pipe escapes through the air holes 141, the solidified material S is also filled in the pipe.
The top end reference surface 140 that is the upper surface of the top plate 139 is exposed and inserted until it is flush with the upper surface of the surrounding solidified material S, and the operation is completed.

The top plate 139 constituting the top end reference surface 140 has an enlarged diameter and acts to prevent dropping, so that it does not settle in the solidified material S, and the top end reference surface 140 is maintained in an exposed state.
This can be used as a guide for adjustment when the top level is stopped. Before the solidified material S is solidified, as shown in FIG. 22 (d), the measuring bar 143 can be placed on the top end reference surface 140 and the level can be measured using the level device 145. By inserting 140 so that 140 becomes slightly higher in advance, and then finely adjusting the insertion depth based on the measurement result, the top level stop can be accurately and easily performed. In addition, the top is beautiful with a smooth metal surface, so it looks good.
Although the bleeding phenomenon is considerably suppressed by adding an inhibitor to the solidified material S, it still appears slightly, and the upper surface of the columnar pile K around the bending reinforcing steel pipe 131 may be slightly lowered. In that case, the top end reference surface 140 may be adjusted to be flush by applying mortar or the like. On the contrary, when the solidifying material S is injected a little more, the solidifying material S around the top end reference surface 140 is raised, but in that case, the raised portion is scraped off. The top reference plane 140 may be adjusted to be flush with each other.

  Thereafter, when the solidified material S is solidified, the columnar pile K is formed as shown in FIG. The bending reinforcing steel pipe 131 is surrounded and fixed by the columnar pile K.

  In FIG. 22, the steel pipe 131 for bending reinforcement is long and extends over almost the entire length of the columnar pile K. However, since the bending moment is mainly applied to the side close to the foundation, when the columnar pile K becomes long, The steel pipe 131 for bending reinforcement is shorter than that, and may be designed to be, for example, about 1/3. However, even in such a case, the action of preventing the top end adjustment cap 135 from dropping works, so the top end reference surface 140 is The exposed state is maintained.

  The embodiment of the present invention has been described in detail above. However, the specific configuration is not limited to this embodiment, and the present invention can be changed even if there is a design change without departing from the gist of the present invention. included.

1 ... casing for ground reinforcement (first embodiment)
DESCRIPTION OF SYMBOLS 3 ... Casing main body 5 ... Screw blade 7 ... Overhang | projection part 9 ... Upper same diameter cylinder part 11 ... Lower side inclination cylinder part 13 ... Step part 15 ... Connection cylinder part 17 ... Half-divided member 19 ... Matching piece 21 ... Matching piece DESCRIPTION OF SYMBOLS 23 ... Bolt 25 ... Stopper metal fitting 27 ... Half-shaped metal fitting 29 ... Embedding part 31 ... Matching piece 33 ... Bolt 35 ... O-ring 37 ... Feed pipe 39 ... Discharge port 41 ... Push block 43 ... Tip part 45 ... Connection part 47: Bit portion 49 ... Receiving block 51 ... Upper half portion 53 ... Lower half portion 61 ... Ground reinforcing casing (second embodiment)
63 ... Overhanging portion 65 ... Upper same-diameter cylindrical portion 67 ... Intermediate inclined cylindrical portion 69 ... Lower same-diameter cylindrical portion 71 ... Lowering portion 73 ... Lower piece 72 ... Insertion hole 75 ... Pin 77 ... Lifting prevention metal fitting 79 ... Wall portion 81 ... Mounting part 82 ... Insertion hole 83 ... Bolt 85 ... Rubber packing 87 ... Rubber packing 89 ... Inner flange 91 ... Connecting piece 93 ... Ground reinforcement casing (third embodiment)
DESCRIPTION OF SYMBOLS 95 ... Casing main body 97 ... Fixing cylinder part 99 ... Concave part 101 ... Push-up pipe 103 ... Discharge cylinder part 105 ... Discharge hole 107 ... Bit part 109 ... Overhang part 111 ... Upper same diameter cylinder part 113 ... Bottom Side inclined cylinder part 115 ... protective cylinder part 117 ... fixing cylinder part 119 ... curved surface 121 ... insertion hole 123 ... insertion hole 125 ... through hole 127 ... concave strip part 129 ... pin shaft 131 ... steel pipe for bending reinforcement 133 ... steel pipe body 135 ... top end adjustment cap 137 ... fitting cylinder part 139 ... top plate 140 ... top end reference surface 141 ... air hole 143 ... measuring rod 145 ... level device G ... ground P ... consolidation wall S ... solidified material K ... columnar pile H ... Head A ... Pile-shaped support force a ... Surface friction force B ... Ground support force b ... Surface support force

Claims (8)

In the ground reinforcement method for reinforcing the ground by creating columnar piles from the solidification of the solidified material injected into the ground, the ground reinforcing casing used for consolidation of the hole and the hole edge,
A cylindrical casing body having an axial direction as a drilling direction, and a projecting portion that is externally fitted to the casing body and has an outer shape projecting outward in the radial direction of the casing body,
The projecting portion includes a diameter-enlarged portion having the same diameter and a diameter-reduced portion that is connected to the diameter-increased portion on the front side in the drilling direction and is reduced in an inclined shape toward the drilling direction. A ground reinforcing casing, comprising a diameter portion, slidable in an axial direction with respect to the casing body, and appropriately fixed at a predetermined position. In the ground reinforcement casing according to claim 1,
The fixing means for fixing the overhanging portion to the casing main body so as to be immovable in the axial direction and around the axis includes an inner peripheral surface of the fixing cylinder portion continuously provided on the rear side in the drilling direction of the overhanging portion, and the casing main body. The insertion hole is formed across the boundary of the outer peripheral surface and penetrates perpendicularly to the drilling direction and a separate insertion shaft, and is fixed when the insertion shaft is inserted into the insertion hole. Ground reinforcement casing. In the ground reinforcement casing according to claim 2,
A casing for ground reinforcement, wherein the concave portion on the casing body side forming the insertion hole is formed in a thicker portion than the others. In the ground reinforcement casing according to any one of claims 1 to 3,
A ground reinforcing casing, wherein the overhang portion is formed of a casting. In the ground reinforcement casing according to any one of claims 1 to 4,
The distal end portion of the casing body is composed of a tubular taper portion whose diameter is reduced in an inclined manner toward the drilling direction, and a solid bit portion continuously provided on the front side in the drilling direction. A ground reinforcing casing, characterized in that a discharge hole is provided in the part. In the ground reinforcement casing according to any one of claims 1 to 4,
The tip of the casing body rotates with the forward rotation when the drilling proceeds, and is separated from the casing body with the negative rotation during reverse withdrawal and retraction.
A ground reinforcing casing, wherein a slurry-like solidified material is discharged from the dividing port. In the ground reinforcement construction method using the ground reinforcing casing according to any one of claims 1 to 6,
After drilling using the ground reinforcing casing and injecting solidified material into the hole, before the solidified material is solidified, it is inserted so as to be coaxial with the columnar pile forming the bending reinforcing steel pipe The ground reinforcement method characterized by the above-mentioned. A steel pipe for bending reinforcement used in the ground reinforcement method according to claim 7,
With the top adjustment cap, the axial top is closed,
The top end adjustment cap is provided with a top end reference surface having a radially increased diameter, and an air port that passes through the top end reference surface and communicates with the inside of the pipe. Steel pipe.

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