JP2008240270A - Under-reamed pile and under-reamed bucket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an under-reamed pile which enables a base enlargement ratio to be increased even if an under-reamed portion is low, and which hardly causes stress concentration. <P>SOLUTION: In this under-reamed pile 100, the under-reamed portion 102, the diameter of which becomes larger than that of a shaft portion 101, is formed on a portion as the bottom of the pile. The under-reamed portion 102 is provided with a gradually-widened portion 102b which is expanded in a funnel shape downward from the shaft portion 101. Additionally, the gradually-widened portion 102b is formed by rotating an arc, in which a center 102c for connecting an upper end to a lower end of a lateral line of the shaft portion 101 is located on the outside the pile, on the axial center of the pile. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an expanded bottom pile in which an expanded bottom portion that is enlarged from a shaft portion is formed in a portion that becomes a bottom portion of the pile, and an expanded bucket for constructing the expanded pile.

  Conventionally, a bottom-up concrete pile as a cast-in-place concrete pile in which a bottom-up portion expanded from a shaft portion is provided at a portion that becomes a bottom portion of the pile is known (see Patent Documents 1 to 3 and the like).

  This bottomed pile has a standpipe built on the ground, the inside of which is excavated by an excavator to form a shaft part, and the bottom part of the bottomed pile is gradually expanded with a bottomed bucket to cut the bottom part Build by forming the part that becomes.

The widened portion is configured by a truncated conical inclined widened portion whose side line extends linearly downward, and a columnar vertical portion provided below the widened portion.
JP 2004-263561 A JP 2001-164867 A JP 59-490A

  However, in the conventional expanded bottom pile described above, a corner is formed at the boundary between the lower end of the columnar shaft portion and the upper end of the truncated conical inclined widened portion, so stress is concentrated on the corner portion. May cause local destruction.

  In addition, in the conventional building foundation structure design standard (Architectural Institute of Japan), since the inclination angle of the inclined widened portion is regulated to be within 12 degrees, if you want to increase the diameter of the expanded bottom portion relative to the shaft portion, It was necessary to increase the bottom expansion ratio (diameter of the bottom expanded portion / diameter of the shaft portion) by increasing the inclined widened portion.

  However, if the bottom area becomes high, the amount of excavated soil to excavate the ground will increase, and the bottom area bucket to be used will also be large, so it will not be possible to attach it to a small excavator, use a sub-crane, You have to switch to the machine.

  Moreover, since the ground which forms an expanded base part is the ground used as a support layer of a pile, there are many hard grounds, and it was difficult to cut with the conventional expanded bucket.

  Therefore, the present invention provides a bottom-expanded pile that can increase the bottom-expansion rate even when the bottom-expanded portion is low, and is less likely to cause stress concentration, and a bottom-expanded bucket that can easily form the bottom-expanded portion of the pile even in hard ground. It is aimed.

  In order to achieve the above object, the expanded bottom pile of the present invention is an expanded bottom pile in which a bottom expanded portion having a diameter larger than that of a shaft portion is formed in a portion that becomes a bottom portion of the pile, and the expanded bottom portion includes the shaft. It has the gradually widened part which spreads in a morning glory shape toward the downward direction from a part, It is characterized by the above-mentioned.

  Here, the gradually widened portion is formed by rotating an arc whose center is connected to the lower end of the side line of the shaft portion on the outside of the pile around the axis of the pile. it can.

  Moreover, the bottom expansion bucket of this invention is a bottom expansion bucket for forming the bottom expansion part which expanded the diameter rather than the axial part in the part used as the bottom part of a pile, Comprising: The cylindrical main body part and the diameter of the main body part A widened wing portion that is formed so as to be openable so as to expand, and a side end portion of the widened wing portion is formed in a concave curve, and a rotatable roller bit extends in a direction in which the side end portion extends. It is characterized in that a plurality are provided at intervals.

  Here, a fixed bit is fixed between the roller bit and the roller bit at the side end of the widening wing.

  Moreover, it is preferable that the protrusion part is formed in the lower end of the said main-body part below the said widening wing | blade part. Here, an annular stabilizer that adjusts the diameter of the protrusion can be detachably provided.

  Further, the widened wing portion is formed in a shape in which an equal width portion having a substantially constant width is formed in the vicinity of the lower end, and the upper portion thereof is tapered, and the roller bit is formed at a side end portion of the equal width portion. The plate-shaped cutting plate blade portion can be configured to be switchable.

  In addition, a transmission shaft for receiving a force from the ground drill kelly bar is disposed inside the main body so as to be movable in the vertical direction of the main body, and is flexibly connected to the transmission shaft. A lower end of the connecting member is connected to the widened wing portion, and a reduction device may be interposed between the lower end of the kelly bar and the transmission shaft portion.

  Here, the transmission shaft portion is slidably accommodated in a guide tube attached to the inside of the main body portion, and the transmission shaft portion depends on the height of an opening adjustment plate that is detachably attached to the upper end of the guide tube. It can be configured such that the amount of downward movement of the transmission shaft portion is set.

  Further, the transmission shaft portion is slidably accommodated in a guide tube attached to the inside of the main body portion, and a slide groove inclined in a direction intersecting the axial direction is formed on the peripheral surface of the guide tube. In addition, the connecting portion between the transmission shaft portion and the connecting member can be protruded from the slide groove, and the transmission shaft portion can be moved in the vertical direction using it as a guide.

  The bottom expanded pile of this invention comprised in this way forms the gradually widened part which spreads in a morning glory shape from a shaft part.

  For this reason, compared with the shape of the conventional bottomed pile which linearly becomes large in a fixed ratio, even if height is low, the diameter of a bottom expanded part can be enlarged. Moreover, since it spreads in the morning glory shape, there is no place where the shape changes suddenly, and stress concentration hardly occurs.

  Furthermore, by forming a gradually widened portion that extends in a curved line with an arc whose center is on the outside of the pile, it is possible to suppress the magnification that expands in the portion close to the shaft portion, and to greatly increase the bottom expansion rate as it approaches the bottom portion. .

  In other words, it is possible to increase the bottom expansion rate in a short distance while suppressing changes near the boundary between the shaft portion and the bottom expansion portion where stress concentration is likely to occur, so that stress concentration is difficult to occur and stress can be dispersed appropriately. it can.

  In addition, the bottom expansion bucket of the present invention configured as described above is provided with a plurality of rotatable roller bits at the side end portion of the widened wing portion, and the roller bits are cut into a groove shape by biting into the ground. The ground sandwiched between the grooves becomes brittle and it becomes easy to cut. For this reason, even if it is a hard ground, it can be easily expanded.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  Fig.1 (a) is explanatory drawing explaining the structure of the bottom expanded pile 100 of this Embodiment.

  First, to explain from the configuration, the expanded bottom pile 100 includes a shaft portion 101 extending in a columnar shape with a predetermined diameter from the ground, and a bottom expanded portion 102 formed below the shaft portion 101 by expanding the diameter. And mainly consists of

  The expanded pile 100 is a cast-in-place concrete pile formed by building a steel material such as a reinforcing bar in a hole excavated from the ground.

  Further, the expanded bottom portion 102 has a vertical portion 102a as a bottom plate of the expanded bottom pile 100 that rises in a cylindrical shape from the pile bottom with a larger diameter than the shaft portion 101, and a morning glory shape that connects the upper end of the vertical portion 102a and the lower end of the shaft portion 101. It is comprised from the gradually widened part 102b.

  As shown in the side view of FIG. 1A, the gradually widened portion 102b includes a side line that connects the side line of the vertical linear shaft portion 101 and the side line of the vertical portion 102a in a curved line. It is formed in a shape that looks like a flower (or a shape that looks like a mountain skirt).

  The curvilinear side line of the gradually widened portion 102b is formed by an arc having a radius R having a center 102c at a point on the outside of the pile, and the diameter of the gradually widened portion 102b increases as it goes downward. ing.

  Here, if the diameter of the shaft portion 101 is the denominator and the diameter of the bottom expanded portion 102 is the numerator, the bottom expansion rate of the pile is a value obtained by dividing the diameter of the vertical portion 102a by the diameter of the shaft portion 101, and the gradually widened portion 102b. The width expansion ratio obtained by dividing the diameter of the shaft portion 101 by the diameter of the shaft portion 101 gradually increases from 1 as it goes downward, and becomes equal to the bottom expansion rate at the boundary with the vertical portion 102a.

  The increase in the magnification ratio of the gradually widened portion 102b is such that when the radius R is small, the change in the vicinity of the shaft portion 101 is small and rapidly increases in the vicinity of the vertical portion 102a, and increases at a rate close to a constant as the radius R increases. To come.

  On the other hand, FIG.1 (b) is a side view explaining the structure of the conventional cone type bottom expanded pile 8. FIG. The cone-shaped bottom expanded pile 8 includes a cylindrical shaft portion 81 and a bottom expanded portion 82, and the bottom expanded portion 82 includes a vertical portion 82a and a truncated conical inclined widened portion 82b.

  Since the inclined widened portion 82b has a straight oblique side, a corner portion 84 whose shape changes suddenly is formed at the boundary between the shaft portion 81 and the expanded bottom portion 82.

  Moreover, when the inclination | tilt angle of an inclination wide part is 12 degree | times, in the same height as the bottom expansion part 102 of the bottom expansion pile 100 of this Embodiment shown to Fig.1 (a), the dashed-two dotted line of FIG.1 (b) In order to make the bottom expansion ratio the same, it is necessary to make the inclined widened portion 82b higher like the bottom expanded portion 82 indicated by the solid line.

  FIG. 2 is a diagram showing an analysis model 9 of the analysis performed to confirm the shape effect of the expanded pile 100 of the present embodiment.

  This analysis model 9 is a model in which a portion on the right side of the axis of the cross-section of the expanded pile 100 is modeled on the right side of the symmetrical axis 93. The diameter of the shaft portion 101 is D and the expanded diameter of the expanded portion 102 is DW. Model 91 was created.

  Further, three layers of ground models 92 a, 92 b, and 92 c were created around the expanded-pile model 91, and a peripheral surface model 91 a was interposed between the side surfaces of the expanded-pile model 91.

  Further, the vertical boundary 94 of the ground models 92a, 92b, and 92c constrains the movement in the vertical direction, and the horizontal boundary 95 constrains the movement in the horizontal direction.

  The mesh model is not shown in the analysis model 9 shown in FIG. 2, but the inside of the expanded pile model 91, the peripheral surface model 91a, and the ground models 92a, 92b, and 92c are meshes of an appropriate number and shape. It is divided into

  Using the analysis model 9 created in this way, the load W was loaded on the upper end of the expanded bottom pile model 91, and the analysis was performed by the finite element method (FEM).

  FIG. 3A is a diagram schematically showing the stress distribution obtained as a result of the FEM analysis in the right half of the cross section of the bottomed pile 100.

  According to FIG. 3 (a), it can be seen that the maximum stress is widely generated around the center of the curved side surface of the gradually widened portion 102b, and the stress is distributed concentrically around that portion. .

  On the other hand, FIG. 3B is a stress distribution diagram obtained as a result of modeling and analyzing the conical expanded bottom pile 8 for comparison. In this shape, stress concentration occurs in the vicinity of the corner 84, It turns out that it may cause local destruction.

  The stress distribution diagrams of FIGS. 3A and 3B are schematic diagrams and do not show the maximum stress value. However, the maximum stress of the conical expanded bottom pile 8 compared to the maximum stress of the expanded bottom pile 100 ( The stress at the stress concentration portion was 1.2 times or more.

  Table 1 exemplifies a plurality of types of expanded bottom piles 100 whose proof stress was confirmed by punching shear stress and shear stress of FEM analysis.

  In the widened pile 100 of the present embodiment configured as described above, a gradually widened portion 102b that spreads in a morning glory shape from the shaft portion 101 is formed.

  For this reason, even if the height is low, the diameter of the bottom expanded portion 102 can be increased as compared with the shape of the conventional conical bottom expanded pile 8 whose diameter increases linearly at a constant rate. In addition, since the gradually widened portion 102b gradually spreads in a morning glory shape from the shaft portion 101, there is no portion where the shape suddenly changes, and stress concentration hardly occurs.

  Furthermore, if the center 102c is formed with a gradually widened portion 102b that is curved in an arc on the outside of the pile, the magnification spreading in the portion close to the shaft portion 101 can be suppressed, and the bottom expansion rate is greatly increased as it approaches the bottom portion. be able to.

  That is, while suppressing the change near the boundary between the shaft portion 101 and the widened portion 102 where stress concentration is likely to occur, the bottom expansion rate can be increased in a short distance, so that stress concentration is difficult to occur and the stress is appropriately dispersed. be able to.

  Further, if the height of the expanded bottom portion 102 can be reduced, the amount of excavated soil can be significantly reduced, so that the construction period can be shortened and the amount of soil discharged can be reduced.

  Furthermore, if the amount of excavated soil can be reduced, loosening of the tip ground due to stress release during excavation can also be reduced, so that the supporting ground can be kept in a good state.

  Moreover, since the dead weight of the bottom expanded pile 100 can be reduced by making the bottom expanded part 102 small, the amount of applied load can be increased correspondingly.

  Furthermore, since the circumferential area is increased by making the side surface curved as compared with the case of a straight line, the supporting force can be increased when the peripheral frictional force can be included in the supporting force of the pile.

  Hereinafter, the bottomed bucket 1 for constructing the bottomed pile 100 of the above-described embodiment will be described. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  FIG. 4 is a perspective view showing the configuration of the bottom-enlarged bucket 1 of Example 1 used when constructing the bottom-extended pile 100.

  First, in terms of configuration, the bottom expansion bucket 1 of the first embodiment includes a cylindrical main body portion 11 and two widened blade portions 12 and 12 that are formed to be openable so as to increase the diameter of the main body portion 11. And.

  The bottomed bucket 1 is a device that is attached to an earth drill (not shown). Specifically, a pin or the like is provided at the lower end of the kelly bar 2 of the earth drill including a swivel body, a boom, a kelly rope, a kelly bar 2 and the like. It is detachably attached via.

  The main body portion 11 of the bottomed bucket 1 is formed to have a diameter that can be inserted into the excavation hole 60 as shown in FIG. 9 (a) excavated by an excavation bucket (not shown), and an annular stabilizer 4 is formed on the upper portion. Is arranged.

  Further, the widened wing parts 12 and 12 are closed when the bottomed bucket 1 is lifted to form a part of the side surface of the cylindrical main body part 11, and as shown in FIG. When inserted, it is opened and the wall surface of the excavation hole 60 is cut and widened.

  As shown in FIG. 5, the widened wing portion 12 is formed with a uniform width portion 12a having a substantially constant width near the lower end, and a triangular portion 12b having a tapered shape at the upper portion thereof. As shown in FIG.

  The equal width portion 12a is formed to a height of about 500 mm, for example, and a portion cut by the equal width portion 12a becomes a vertical portion 102a as a bottom plate of the expanded pile 100 having a thickness of about 500 mm.

  Further, the triangular portion 12b is formed by an arc having a center on the outer side so that a side end portion which becomes a hypotenuse of a right triangle becomes a concave curve.

  Further, as shown in FIG. 4, a plurality of roller bits 121,... Are provided at the side end portion of the widened wing portion 12 at intervals in the extending direction of the side end portion.

  As shown in FIG. 8A, the roller bit 121 is attached so that the bead-shaped bit portion 121a of the abacus rotates around a shaft 121b fixed to the side end portion.

  In addition, a plurality of fixed bits 122 having a smaller amount of lateral protrusion than the roller bit 121 are fixed between the roller bit 121 and the roller bit 121.

  That is, the roller bit 121 protrudes outward from the fixed bit 122, and the roller bit 121 comes into contact with the excavation wall surface 6 first to cut the ground into a groove shape.

  Further, since the roller bit 121 rotates around the shaft 121b, the generation of excessive stress can be suppressed by rotating when the roller bit 121 is in contact with the hard ground.

  The main body 11 is formed with a notch 11a that can accommodate the roller bits 121, ... and the fixed bits 122, ... when the widened wings 12, 12 are closed.

  And the lower end of the connection member 141 is being fixed to the inner surface below this widening blade part 12, and the widening blade part 12 opens and closes by the force which acts via the connection member 141.

  That is, the transmission shaft portion 14 to which the lower end of the kelly bar 2 of the earth drill is connected is accommodated in the main body portion 11 as shown in FIGS. 4 and 5, and the connecting member 141 is connected to the lower end of the transmission shaft portion 14. The upper ends of the two are connected to each other with a universal joint structure.

  In the first embodiment, the speed reduction device 3 is interposed between the transmission shaft portion 14 and the lower end of the kelly bar 2, and the lower portion of the speed reduction device 3 and the upper end of the transmission shaft portion 14 are connected by the connecting flange 5. Has been. The upper and lower portions of the flange 5 are reinforced by reinforcing plates 5a and 5b as shown in FIG.

  The speed reduction device 3 is a device that operates when a load is applied to the bottom expansion bucket 1 by rotation and increases torque by slowing the rotation of the bottom expansion bucket 1. That is, since the speed reduction and the increase in torque can be achieved by the number of gears combined in the reduction gear 3, the bottom expansion pile 100 having the large diameter bottom expansion portion 102 can be constructed even with a relatively small earth drill. It becomes like this.

  Further, the transmission shaft portion 14 is accommodated in a cylindrical guide tube 15 whose upper end is opened, and is configured to be movable in the vertical direction (axial direction) of the main body portion 11.

  .. Are fixed to the upper and lower portions of the outer peripheral surface of the guide tube 15 by welding or the like, and the other side of the mounting plate 151 is fixed to the inner surface of the main body 11. Has been.

  In addition, oval slide grooves 152, 152 extend in the longitudinal direction of the guide cylinder 15 on the opposing peripheral surface portions of the guide cylinder 15, and are connected to the transmission shaft portion 14 from the slide grooves 152, 152. A connecting bar 142 as a connecting portion for connecting the member 141 is projected.

  As shown in FIG. 6 (cross section AA in FIG. 5), the connecting bar 142 is inserted into a reinforcing tube 14a fitted in a hole penetrating in the direction perpendicular to the axis near the lower end of the cylindrical tubular transmission shaft portion 14. Is done.

  Both ends of the connecting bar 142 are projected from the slide grooves 152, 152, and cylindrical reinforcing covers 142a, 142a are attached to the projected both ends, respectively.

  Then, when the kelly bar 2 is rotated in the R direction in FIG. 6, the rotational force is transmitted to the transmission shaft portion 14 via the speed reduction device 3, so that the transmission shaft portion 14 rotates and is attached to the connecting bar 142 that rotates accordingly. The reinforcing cover 142a, 142a pushes and rotates the guide cylinder 15, and the main body 11 is rotated by the rotational force transmitted through the mounting plates 151, ... attached to the guide cylinder 15.

  The upper ends of connecting members 141 and 141 extending in opposite directions are fixed to the reinforcing covers 142a and 142a, respectively, so as to be freely bent.

  Further, the lower end of the connecting member 141 is flexibly connected to a fixed portion 141a attached to the inner surface of the widened wing portion 12 as shown in FIG.

  When the bottomed bucket 1 configured in this manner is in a state in which the transmission shaft portion 14 is pulled up with respect to the main body portion 11 as shown by a two-dot chain line in FIG. 5, the reinforcing cover 142a of the connecting bar 142 is provided with the slide groove 152. The connecting member 141 stands up and the widened wings 12 and 12 are closed.

  When the transmission shaft portion 14 moves downward from this state, the reinforcing cover 142a is lowered along the slide groove 152, and the upper and lower universal joints of the connecting member 141 are bent, so that the connecting member 141 is inclined and the widened blades are bent. The parts 12 and 12 are pushed out to the side and opened (see the solid and broken lines in FIG. 5).

  FIG. 7 is a plan view showing a state in which one widened blade 12 is opened and the other widened blade 12 is closed in order to explain the movement of the widened blades 12, 12. Will not be in such a state, and the widened wings 12 and 12 open and close simultaneously.

  As shown in FIG. 7, the widened blade portion 12 can form an annular widened portion having a width substantially the same as the diameter before widening, in other words, the maximum widened portion 120 having a diameter nearly three times larger.

  Further, a closing blade stopper 125 is provided inside the main body portion 11 so as not to enter the inside of the widening blade portion 12 when the widening blade portion 12 is closed. The widened wing part 12 is stopped at a predetermined position by contacting the inner peripheral surface near the part.

  Further, the lower end of the connecting member 141 is connected to the fixing portion 141a attached to the inner peripheral surface of the widened wing portion 12 so as to be freely bent, but the widened wing portion 12 is opened as shown in FIG. The extending direction of the connecting member 141 changes between when it is closed and when it is closed.

  Further, as shown in FIGS. 4 and 5, a projecting portion 13 is formed at the lower end of the main body portion 11 below the widened wing portions 12 and 12. For example, the protruding portion 13 having a height of about 200 to 600 mm is provided for the bottomed bucket 1 having a height of about 3 m.

  Further, a conical lid portion 131 is attached to the projecting portion 13 so as to be freely opened and closed. As shown in FIG. 10, the excavated sediment accumulated in the main body portion 11 is discharged by opening the lid portion 131.

  Next, the construction method of the expanded bottom pile 100 of Example 1 will be described and the operation thereof will be described.

  First, a drilling bucket (not shown) is attached to the lower end of the ground drill kelly bar 2 to construct a cylindrical drilling hole 60 as shown in FIG.

  Then, once the excavation bucket is lifted from the excavation hole 60 and removed from the kelly bar 2, the bottom expansion bucket 1 is attached to the lower end of the kelly bar 2 instead.

  In this state, the bottom expansion bucket 1 is lowered to the excavation hole 60, and the lower surface of the bottom expansion bucket 1 is brought into contact with the bottom of the excavation hole 60 to obtain the state shown in FIG.

  Subsequently, when the earth drill is driven to rotate the kelly bar 2, the bottom expansion bucket 1 starts rotating by the rotational force transmitted by being decelerated by the reduction gear 3. By interposing the speed reduction device 3, even when the resistance force against the rotation of the bottom expansion bucket 1 is large, it can be rotated with a small torque of the kelly bar 2.

  Moreover, since this reduction gear 3 can be accommodated in the inside of the main-body part 11, the height required in order to attach the bottom expansion bucket 1 to the kelly bar 2 can be made low, and it becomes a comparatively small-sized earth drill. Can also be attached.

  Thus, in the state where the bottom surface of the widened bucket 1 is brought into contact with the bottom of the excavation hole 60, the main body 11 of the widened bucket 1 does not fall any further. On the other hand, the transmission shaft portion 14 to which the weight of the Kelly bar 2 is transmitted is lowered along the guide tube 15.

  Then, when only the transmission shaft portion 14 is lowered in a state where the main body portion 11 is not lowered, the lower end of the connecting member 141 that is flexibly connected to the lower end thereof spreads outward, and the widened wing portions 12 and 12 are slightly opened. .

  A plurality of roller bits 121,... And fixed bits 122,... Are provided at the side ends of the widened wings 12, 12, and as shown in FIG. The excavation wall surface 6 is cut into a groove shape by... And the ground therebetween is scraped by the fixed bits 122.

  That is, since the roller bit 121 has an acute-angled shape toward the outside, it is easy to bite into hard ground, and when the ground soaked is too hard and has high resistance, it rotates to avoid generating excessive stress. Therefore, the bit part 121a is hardly damaged or worn out in a short time.

  Further, by cutting the ground into a groove shape in advance by the roller bits 121,..., The ground between the grooves is less likely to collapse because the upper and lower restraining forces become smaller, so the fixed bits 122,. It can be scraped off efficiently, and the load acting on the fixed bits 122,... Can be reduced.

  When the excavation wall surface 6 is cut, the widened blades 12 and 12 are more likely to spread outward, so that the bottomed bucket 1 rotates with the rotation of the kelly bar 2 and the widened blades 12 and 12 are gradually opened. The degree is increased, and finally, an expanded bottom portion 60b as a widened excavation hole with a morning glory lying on a cylindrical shape as shown in FIG. 9B is formed.

  Further, when the widened wings 12 and 12 start to open, the protruding portion 13 is embedded as shown in FIG. 9B and is restrained by the ground, so that the resistance during widening is reduced. Even if it becomes larger, the position of the lower end of the widened bucket 1 does not shift, and the left and right opening degrees of the widened wings 12 and 12 are equalized, so that an accurate shaped widened part 60b can be formed at an accurate position. .

  The excavation hole 60 of the expanded pile 100 drilled in this way can expand the expanded portion 60b to approximately 2000 mm with respect to the shaft portion 60a having a diameter of approximately 900 mm, for example.

  On the other hand, the excavated earth and sand generated during the widening excavation is collected inside the main body 11 by the rotating widening blades 12 and 12.

  When the kelly bar 2 is lifted, the transmission shaft portion 14 rises along the guide tube 15, the connecting member 141 connected to the transmission shaft portion 14 rises and the widened wing portions 12, 12 are closed.

  If the lifting of the kelly bar 2 is further continued in this state, the reinforcing cover 142a of the connecting bar 142 comes into contact with the upper end of the slide groove 152, and the main body 11 is lifted.

  When the bottomed bucket 1 in which the excavated earth and sand is housed in this way is moved to the dumping site and the lid 131 is opened as shown in FIG. 10, the excavated earth and sand are discharged from the bottomed bucket 1.

  Further, the excavation wall surface 6 cut by the roller bits 121,... And the fixed bit 122 may be uneven as shown in FIG. When the formation is desired, the bottomed bucket 1 is pulled up once to remove the excavating blade to which the roller bits 121,... Are fixed from the attaching / detaching portion 124. Instead, a plate-shaped cutting plate blade as shown in FIG. The part 123 is fixed to the side end part of the widened wing part 12 through the attaching / detaching part 124.

  Then, the bottomed bucket 1 is inserted into the drilling hole 60 again to rotate the kelly bar 2 and the widened blades 12 and 12 are widened. 6 can be formed.

  The bottomed pile 100 made of cast-in-place concrete is completed by inserting a reinforcing bar into the excavation hole 60 thus excavated and placing concrete.

  Hereinafter, another embodiment of the bottomed bucket 1 described in the first embodiment will be described. The description of the same or equivalent parts as those described in the above embodiment or Example 1 will be given the same reference numerals.

  FIG. 11 is a view showing a state in which the opening adjustment plate 7 is arranged on the upper surface of the guide cylinder 15 in order to adjust the descending amount of the transmission shaft portion 14.

  In other words, in the first embodiment, the reinforcing cover 142a of the connecting bar 142 is brought into contact with the lower end of the slide groove 152 to widen the widened wings 12 and 12 to the maximum extent. In some cases, it is not necessary to increase the width until the portion 120 is reached.

  Therefore, a plate-shaped opening degree adjustment plate 7 having a through hole larger than the diameter of the transmission shaft portion 14 can be arranged on the upper surface of the guide tube 15 so that the transmission shaft portion 14 can be adjusted so as not to be lowered too much. The amount of movement of the transmission shaft portion 14 can be adjusted by the height of the opening adjustment plate 7, and this height is adjusted by the height or number of sheets per sheet.

  Further, the opening adjusting plate 7 can be easily mounted from the side surface of the transmission shaft portion 14 by being divided in half and connected to be freely opened and closed by a hinge.

  In the second embodiment, the speed reducer 3 arranged in the first embodiment is not attached, and the lower end of the kelly bar 2 is connected to the upper end of the transmission shaft portion 14 by the connecting flange 5.

  Further, reinforcing plates 5a,... Are attached to the lower surface of the connecting flange 5, and are reinforced so as not to be deformed even when they collide with the opening adjustment plate 7.

  When the transmission shaft portion 14 is lowered to a predetermined position, the lower surface of the connecting flange 5 comes into contact with the opening adjustment plate 7, and the transmission shaft portion 14 does not lower below that.

  When the lowering of the transmission shaft portion 14 stops in this way, the widened wing portions 12 and 12 also stop in a partially open state, and the desired size of the expanded bottom portion 60b can be maintained.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or Example 1, and thus description thereof is omitted.

  Hereinafter, a bottom-up bucket having a different form from the first and second embodiments will be described. The same or equivalent parts as those described in the first and second embodiments will be described with the same reference numerals.

  In the third embodiment, as shown in FIG. 12, a case where a guide cylinder 15A having a slide groove 152A obliquely provided on the peripheral surface is used will be described.

  The guide tube 15A is a cylindrical tube member that is open at least at the top, and is fixed to the inner surface of the main body 11A via mounting plates 151A and 151B fixed to the upper and lower portions of the outer peripheral surface.

  Further, as shown in FIGS. 12A and 12B, a slide groove 152A inclined in a direction intersecting the axial direction is formed on the peripheral surface of the guide cylinder 15A. Here, FIG. 12A is a cross-sectional view taken along the line CC in FIG. 12B, and FIG. 12B is a side view seen from the direction BB in FIG.

  Cylindrical reinforcing pipes 153 and 153 are disposed and reinforced on both sides of the slide groove 152A.

  The guide tube 15A accommodates the transmission shaft portion 14 such that the reinforcing cover 142a of the connecting bar 142 provided at the lower end of the transmission shaft portion 14 protrudes from the slide groove 152A.

  When the transmission shaft portion 14 moves in the vertical direction while rotating, the protruding reinforcing cover 142a moves up and down while changing the direction. That is, as shown in FIG. 12B, the reinforcing cover 142a protrudes to the left in the drawing when it is in contact with the upper end of the slide groove 152A, and protrudes in the direction perpendicular to the paper surface when it is in contact with the lower end.

  By configuring the reinforcing cover 142a to be connected to the connecting member 141 in this manner so as to move up and down while rotating around the guide cylinder 15A, it is possible to cancel the torsion that occurs when the widened wings 12 and 12 are opened and closed. The widened wings 12 and 12 can be smoothly opened and closed without generating excessive stress on the connecting member 141 or the universal joint.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or Examples 1 and 2, and thus description thereof is omitted.

  Hereinafter, a fourth embodiment different from the first embodiment will be described. Note that the same or equivalent parts as those described in the first embodiment will be described with the same reference numerals.

  In the fourth embodiment, a case will be described in which the widened portion 60b is formed in the excavation hole 60 in which the shaft portion 60a having a diameter larger than that of the main body 11 is excavated.

  When the bottomed bucket 1 is inserted into the excavation hole 60 having a diameter larger than that of the main body portion 11 in this way, a gap is opened between the main body portion 11 and the wall surface of the excavation hole 60, and as shown in FIG. The stabilizer 4 and the lower stabilizer part 133 are projected over the upper and lower parts of the body so that the main body part 11 does not deviate from the center position when the floor is expanded.

  That is, in the upper stabilizer 4, the ¼ arc-shaped slide plate 4 a,... Is pushed out in the diameter direction, and fills the space between the main body 11 and the wall surface of the excavation hole 60. Further, as shown in FIG. 14, the lower stabilizer portion 133 is disposed in an annular shape on the outer periphery of the body portion 132 having the same diameter as the main body portion 11, and between the body portion 132 and the wall surface of the excavation hole 60. fill in.

  As described above, the protruding portion 13A of the fourth embodiment includes the cylindrical body portion 132, the annular lower stabilizer portion 133 disposed on the outer periphery thereof, and the conical lid portion 131 that closes the lower surface of the body portion 132. It is mainly composed by.

  The lower stabilizer 133 is formed by connecting four arc portions 133a,..., Which are, for example, 1/4 arc-shaped steel boxes, and the circumferential end of the arc portion 133a. Are formed with ridges 133b and ridges 133c extending in the diameter direction.

  Then, the protrusions 133b and the recesses 133c of the arc part 133a are inserted into the recesses 133c and the protrusions 133b of the arc parts 133a and 133a on both sides thereof, and the adjacent arcs by bolts 133e as shown in FIG. The parts 133a,... Are joined together.

  Further, as shown in FIG. 14, a convex portion 133 d is formed in the approximate center of the inner peripheral surface of the arc portion 133 a, and a concave portion 132 a into which the convex portion 133 d is fitted is formed on the outer peripheral surface of the body portion 132. (See FIG. 13).

  Then, the convex portion 133d is fitted into the concave portion 132a by bringing the inner peripheral surface of the arc portion 133a into contact with the outer peripheral surface of the body portion 132, and both are joined by a bolt 134 as shown in FIG.

  Thus, if the outer peripheral surface of the lower stabilizer part 133 is continuously formed in the same plane, when the widened wing parts 12 and 12 are opened by rotating the bottom widened bucket 1, the temporarily eccentric load is projected. Even if it acts on 13A, the lower stabilizer 133 does not bite into the excavation wall surface 6 and prevent the bottom-up bucket 1 from rotating.

  Further, the lower stabilizer portion 133 is firmly integrated by inserting the protrusion 133b into the recess 133c, and is also firmly integrated with the body portion 132 by fitting the protrusion 133d and the recess 132a. Yes.

  For this reason, when the bottom expansion bucket 1 is rotated, it sufficiently resists the shearing force generated between the body portion 132 and the lower stabilizer portion 133 and the shearing force generated between the arc portions 133a,. be able to.

  Since the resistance received from the ground when opening the widened wing parts 12 and 12 is larger in the lower part than in the upper part of the widened bucket 1, only the lower stabilizer part 133 is formed in an annular configuration in the fourth embodiment. However, the present invention is not limited to this, and the upper stabilizer 4 can be configured in the same manner as the lower stabilizer portion 133.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  The best mode and examples of the present invention have been described in detail above with reference to the drawings. However, the specific configuration is not limited to this mode and examples, and does not depart from the gist of the present invention. A degree of design change is included in the present invention.

  For example, in the above embodiment, the side surface of the gradually widened portion 102 is formed in a morning glory shape by rotating an arc around the axis of the pile, but is not limited to this, and the lower end of the shaft portion 101 and the vertical portion The upper end of 102a should just be connected with the concave curve which turned the outer periphery to the axial center side of the pile.

  Moreover, although the bottom expansion bucket 1 was demonstrated in Example 1 thru | or 4 as an apparatus which constructs the bottom expansion pile 100, it is not limited to this, The bottom expansion part 102 is formed by the bottom expansion bucket of another mechanism, a deep foundation method, etc. You may build the expanded bottom pile 100 which spreads in a morning glory shape. Moreover, although the bottomed pile 100 of the said embodiment does not show the part formed by the protrusion parts 13 and 13A of Examples 1-4, it is not necessary to provide this part.

  Further, in the first embodiment and the like, the roller bits 121,... Are provided above the widened wings 12, 12, but the present invention is not limited to this, and the roller bits 121,. If the ground to be excavated is soft, the adjustment can be performed by removing the upper roller bits 121.

  Moreover, although the said Example 1 etc. demonstrated the planar view circular arc plate-shaped wide wing | blade part 12, it is not limited to this, For example, the triangular part 12b may be a frame structure. Further, the main body portion 11 only needs to be formed in a circular arc plate shape so as to close the space between the equal width portions 12a and 12a, and a triangular portion extending upward is omitted from that portion. Can be.

  In the first embodiment, the configuration in which the speed reduction device 3 is accommodated in the bottomed bucket 1 has been described. However, the configuration is not limited to this. For example, the speed reduction device 3 and the stabilizer 4 are integrally configured. It may be.

(A) is explanatory drawing explaining schematic structure of the bottom expanded pile of the best embodiment of this invention, (b) is explanatory drawing explaining schematic structure of the conventional cone type bottom expanded pile. It is explanatory drawing of the analysis model for performing the analysis of the bottom expansion pile of the best embodiment of this invention. (A) is a schematic diagram explaining the stress distribution of the bottom expansion pile of the best embodiment of this invention, (b) is a schematic diagram explaining the stress distribution of the conventional cone type bottom expansion pile. It is a perspective view explaining schematic structure of the bottom expansion bucket of Example 1. FIG. It is a side view explaining the structure of an expanded bucket. It is AA sectional drawing of FIG. It is explanatory drawing for demonstrating the widening range of a widening wing | blade part. (A) is an enlarged detail drawing for demonstrating the excavation shape of a roller bit, (b) is an enlarged detail drawing for demonstrating the excavation shape of a cutting-plate blade part. (A) is explanatory drawing which showed the state which arranged the bottom expansion bucket in the excavation hole before widening, (b) is explanatory drawing which showed the state of the bottom expansion part and bottom expansion bucket at the time of widening. It is a perspective view explaining the soil discharging method of an expanded bucket. It is sectional drawing which showed the structure of the bottom expansion bucket which has arrange | positioned the opening degree adjustment plate of Example 2. FIG. It is a figure explaining the structure of the guide cylinder of Example 3, Comprising: (a) is CC sectional drawing of (b), (b) is the side view seen from the BB line direction of (a). . It is a perspective view explaining the schematic structure of the bottom expansion bucket which provided the lower stabilizer part of Example 4. FIG. It is the top view which looked at the structure of the protrusion part of Example 4 from the top.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Expanded bottom pile 101 Shaft part 102 Expanded bottom part 102a Vertical part 102b Gradually widened part 102c Center 1 Expanded bucket 11, 11A Main body part 12 Widened wing part 12a Equal width part 12b Triangular part 121 Roller bit 122 Fixed bit 123 Cutting plate blade part 124 Detachable part 13, 13A Protruding part 133 Lower stabilizer part (stabilizer)
14 Transmission shaft part 142 Connection bar (connection part)
142a Reinforcing cover (connecting part)
141 Connecting member 15, 15A Guide tube 152, 152A Slide groove 2 Kelly bar 3 Deceleration device 60a Shaft 60b Expanding bottom 7 Opening adjustment plate

Claims (3)

A bottomed pile in which a bottomed portion having a diameter larger than that of a shaft portion is formed in a portion that becomes a bottom portion of the pile,
The said bottom expansion part has a gradually widening part which spreads in a morning glory shape toward the downward direction from the said axial part, The bottom expansion pile characterized by the above-mentioned.   The gradually widened portion is formed by rotating an arc whose center is connected to the lower end of the side line of the shaft portion on the outer side of the pile around the axis of the pile. Expanded bottom pile described in 1. A bottom expansion bucket for forming a bottom expanded portion having a diameter larger than that of a shaft portion in a portion to be a bottom portion of a pile,
A cylindrical main body portion and a widened wing portion that can be opened so as to increase the diameter of the main body portion are provided, and the side end portion of the widened wing portion is formed with a concave curve and is rotatable. A plurality of roller bits are provided at a distance in the extending direction of the side end portion of the roller bit.

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