JP4099199B2 - Open-ended type ready-made pile and excavation head used therefor - Google Patents

Description

  The present invention relates to a ready-made pile with open ends and a drilling head used therefor, which has a small amount of soil removal and good penetration from the ground surface regardless of the geology.

  For example, when constructing a structure such as a low-rise building such as a wooden house on a ground with low bearing capacity such as a landfill or embankment, it is necessary to It is necessary to place, press-fit, or construct a pile that reaches the support layer, or a pile that obtains a support force by frictional force with the ground in the ground.

  When an off-the-shelf pile is used as the pile, the pile is often inserted into the ground by rotary press-fitting from the viewpoint of reducing the influence on nearby areas such as vibration and noise. Moreover, in order to suppress the amount of soil discharged during excavation, the use of an open-ended pile is suitable, but a spiral blade or wing may be fixed to the tip of the pile to assist in press-fitting by rotation ( Patent References 1 to 5).

Japanese Patent Laid-Open No. 11-247183 (FIGS. 1 and 6 to 9) Japanese Patent Laid-Open No. 2001-73365 (FIGS. 1, 2, 4, and 5) Japanese Patent Laid-Open No. 11-93163 (FIGS. 2 and 3) Japanese Patent Laying-Open No. 2005-42457 (FIGS. 1, 2, and 6) JP-A-9-151456 (FIGS. 2 and 3)

  In the pile which protruded the wing | blade which has a width | variety large at the front-end | tip of a pile main body like the patent documents 1-4, and specifically about the width of a half of a pile diameter, there exists an advantage which obtains high support force from a ground after fixation. . However, since the resistance received until reaching the target progress is large, it is not suitable for insertion on a hard ground, and there is a possibility that a boulder will bounce back if there is a boulder in the ground to be excavated. In particular, because the resistance received by the wings is large, the torque required to rotate the pile body becomes excessive, and the frictional resistance received from the earth and sand also increases. Therefore, high power is required for the motor for rotating and press-fitting the pile body. .

  Furthermore, in the case of Patent Documents 1 to 4, because the wing protrudes to the outer periphery of the pile body, the range of earth and sand to be cut during excavation becomes wider and disturbs the earth and sand in the region about twice the diameter of the pile. Only by doing this, the horizontal resistance force received from the surrounding ground after the penetration of the pile body is reduced. For this reason, the process for ensuring the stability with respect to the horizontal force which a pile main body receives, such as filling a mortar in a ground after penetration of a pile main body, is needed.

  In patent document 4, while making a wing | blade protrude also to the inner peripheral side of a pile main body, while trying to suppress the inflow of the earth and sand to the inside of a pile main body, it is going to reduce the bending stress which arises in a pile main body. However, as a result of the wing projecting to the inner peripheral side of the pile body, the inflow of earth and sand into the pile body is likely to be prevented, so that the portion below the wing is likely to be clogged with sand and the press-fit of the pile body may be hindered There is.

  In FIG. 6 of Patent Document 4, an attempt is made to increase excavation efficiency by projecting an excavating blade having a different length at the tip of the pile body, but the excavating blade does not serve to assist the inflow of earth and sand into the inside of the pile body. It does not prevent clogging of the earth and sand described above.

  In Patent Document 5, a cutting claw for cutting and a spiral guide blade for assisting the press-fitting of the pile main body are projected at the tip of the pile body, but the cutting claw and the guide blade are separated and discontinuous. Therefore, the tip of the guide blade may receive resistance from the ground. In particular, since the guide blade is located above the extension line (spiral) of the cutting claw, the earth and sand cut by the cutting claw is likely to enter the lower surface side of the guide blade, which may hinder smooth penetration of the pile body.

  In view of the above background, the present invention proposes an open-ended pre-made pile with a small amount of soil removal and good penetrability regardless of geology, and an excavation head used therefor.

Open tip ready piles of claim 1, the outer peripheral surface of the distal end portion of the pile body, the double several blades inclined with respect to the timber axis of the pile body is protruded tip portion of said blade Projecting from the tip position of the pile body to the excavation side across the outer peripheral surface and the inner peripheral surface of the pile body, and the blade is spirally continuous from the tip portion to the outer peripheral surface of the pile body , The blade formed by being bent or curved convexly upward at an intermediate portion in the length direction, and gradually bent or curved downward in the width direction on the upper side across the intermediate portion in the length direction of the blade, It is a constituent requirement to provide a pressing piece for pressing the cut earth and sand against the hole wall . The tip of the pile body and the tip of the blade point to the lower end of each.

  The blade projecting from the outer peripheral surface of the pile body tip continues from the tip position of the pile body to the outer surface, so that the earth and sand cut by the blade tip moves on the upper surface of the blade along with the excavation by the rotation of the pile body. Since the blade is carried along the cutting position, the resistance that the blade receives from the earth and sand in the ground is small, and the penetration is improved. In particular, since the tip of the blade protrudes from the tip of the pile body, the possibility that the pile body is damaged even in hard ground is low.

  Moreover, the tip of the blade straddles the outer peripheral surface and inner peripheral surface of the pile body, so that the earth and sand existing on the outer peripheral side and inner peripheral side of the pile main body can be cut, and the outer peripheral surface and inner peripheral surface of the pile main body are In order to reduce the resistance received at the time of penetration, penetration of the pile body into the ground will be helped. This resistance reduction effect by cutting the blade tip functions effectively when the pile is penetrated into hard ground that is difficult to penetrate. When there is a gravel layer or a boulder in the process of penetrating the pile body, a super steel tip for protecting this may be attached to the tip of the blade.

  Since the tip of the blade straddles the outer peripheral surface and the inner peripheral surface of the pile main body, the portion above the front end protrudes from the outer peripheral surface of the pile main body. However, it does not prevent the inflow of earth and sand into the inside of the pile body as in the case of projecting. Therefore, clogging of earth and sand inside the pile main body is avoided, and the penetration of the pile main body is not hindered due to this.

While blade to prevent damage to the pile body, but sufficient that at least one projecting on the outer peripheral surface of the pile body on which is penetrated without resistance in the ground, the center of the pile body as claimed in claim 7 In the case where a plurality of nozzles are equally arranged in the circumferential direction, and a plurality of them are provided to protrude evenly in the circumferential direction, stability during penetration is obtained and verticality is maintained. As a result, the possibility that the pile body tilts during penetration also with respect to hard ground is reduced.

  The soil cut by the blade tends to move upward relative to the pile body along the upper surface of the blade as the pile body penetrates. Sediment that stays on the blade tries to fall from the upper end of the blade by being pushed by the sand pushed up from below, but if the sediment is highly viscous, it will be compacted and lumped on the blade until it falls. there is a possibility.

  Here, when the blade is straight (as a simple spiral) as seen from the side surface of the pile body as in Patent Document 5, when the earth and sand are consolidated, the blade extends from the tip to the upper end. In the section, the earth and sand try to stay on the blade and try to fall in a lump. Even if it is not consolidated, the sediment on the blade is only pushed down by the sediment from below and falls, so the sediment in the borehole is simply loosened. If the earth and sand is a viscous earth, it is easy to maintain the state where the earth and sand are attached to the blade due to the viscosity. Therefore, it is easy to deposit on the blade, and it is difficult to naturally drop the earth and sand from the blade.

On the other hand, when the blade is bent upward or convex at the intermediate portion in the longitudinal direction as described in claim 1 , the material shaft of the pile body sandwiching the position of the intermediate portion Therefore, the earth and sand placed on the blade at the portion where the angle changes can be naturally dropped from the blade as the pile body rotates. The middle part of the blade bends upwards, etc., so that the earth and sand placed on the blade can be easily separated from the state attached to the blade during rotation of the pile body, including the case of viscous soil. Is difficult to maintain, and as a result, it tends to fall off the blade.

  When falling from above the blade, the earth and sand are subjected to centrifugal force and fall from a position near the hole wall of the pile body, so that after falling from the blade, the earth and sand are easily pressed against the hole wall side by the side surface of the blade passing through that position. When the cut earth and sand are pressed against the hole wall, the hole wall is hardened and the stability of the hole wall is easily secured. In the case of Patent Document 5, since the earth and sand cut by the cutting claws easily enter the lower surface side of the guide blade, the effect of the guide blade pressing the earth and sand against the hole wall is not expected.

The blade according to claim 1 is formed from a single plate such as a steel plate, or a plurality of blade configurations such as plates and flat bars divided in the length direction of the blade as described in claim 4 Sometimes it is made of wood. In this case, the plurality of blade components are divided, for example, at positions where the blades are bent at an intermediate portion in the length direction.

In addition, as described in claim 2, when the portion of the blade located on the hole wall side with respect to the pile body is bent or curved in the width direction so that the hole wall side is convex when the pile body is viewed in the circumferential direction. In this case, the sediment on the blade can be easily dropped from the bent portion of the blade toward the hole wall, so that sedimentation of the sediment can be easily avoided.

  At the same time, the blades stabilize the hole wall and prevent its collapsing because it becomes easy to exert the effect of pressing the earth and sand falling from the blade against the hole wall with the rotation of the pile body. Contribute. The function of pressing the earth and sand falling from the blade against the hole wall is bent in the width direction so that the hole wall side is convex, and the part facing the hole wall fulfills the function.

When the blade is a flat plate, the falling of the earth and sand placed on the blade is not promoted, so the cutting earth and sand are sequentially fed as described above, so that the earth and sand are gradually consolidated, and the earth and sand are rotated when the pile body rotates. Can become a resistance. On the other hand, in the first to third aspects, since the fall of the cut soil is promoted, the possibility of consolidation on the blade is reduced, and the generation of resistance due to the consolidation of the cut soil is avoided or alleviated.

Specifically, the blade according to claim 2 has a shape in which the blade is twisted from the position near the tip to the upper end as described in claim 3 , so that the outer periphery of the pile body of the blade can be obtained. A portion far from the surface is bent or curved in the width direction so that the hole wall side is convex.

The blade according to claim 2 is also formed from a single plate or the like, and is composed of a plurality of blade components such as plates and flat bars divided in the width direction of the blade as described in claim 4. In some cases. In the case where the blade is twisted in claim 1 (claim 3), the shape of the blade is bent like the upper portion in the width direction from a position which is bent like a convex upward.

Since the blade according to any one of claims 1 to 4 protrudes from the outer peripheral surface of the pile body to the hole wall side and has an upper surface facing upward and a lower surface facing downward, the penetration of the pile body into the ground is completed. When the pile main body supports the superstructure, in addition to the frictional force on the inner peripheral surface and the outer peripheral surface of the pile main body, a frictional force acts between the surrounding earth and sand on the upper and lower surfaces of the blade. Since this frictional force is added to the peripheral surface frictional force of the pile body, it contributes to the improvement of the supporting force as a whole pile.

  Moreover, when the wing | blade of the magnitude | size which block | closes the cross section is projected at the front-end | tip of a pile main body like patent document 4, earth and sand do not enter in a pile main body, and the inner peripheral surface of a pile main body is exposed to air Therefore, it is necessary to fill the tip of the pile body with concrete or the like in order to prevent corrosion due to groundwater. On the other hand, in the present invention, since earth and sand enter the pile main body and the inner peripheral surface of the pile main body is protected by earth and sand, treatment for preventing corrosion such as filling with concrete is not required. By eliminating the need for filling with concrete or the like, the material containing cement does not enter the groundwater, so there is no problem of groundwater contamination. Furthermore, since soil and sand enter the pile body, there is no need for soil removal, so there is no problem of residual soil treatment.

  The earth and sand cut by the tip of the blade is pressed against the hole wall by the portion above the tip, but the pile body is once inserted into the excavation hole formed by loosening the earth and sand by the blade. Here, if the distance between the outer peripheral surface of the pile main body and the hole wall of the excavation hole is larger than the outer diameter of the pile main body, the pile main body tends to be inclined in the excavation hole and may become unstable. . Therefore, in order to stabilize the pile body in the excavation hole, it is preferable that the width of the blade, that is, the protrusion width from the outer peripheral surface of the pile body is small.

On the other hand, in order to ensure the penetrability of the pile main body, it is necessary for the blade to loosen the earth and sand in a certain region. From the above, it is appropriate that the width of the blade is specifically in the range of 0.01 to 0.5 times the outer diameter of the pile body as described in claim 5 . The width of the blade varies depending on the pipe thickness of the pile body, but it is appropriate that the blade width is within the above range even if this point is included.

  If the width of the blade is less than 0.01 times the outer diameter of the pile main body, the effect of the blade loosening the ground around the pile main body is small, so that the pile main body is difficult to penetrate into the excavation hole. On the other hand, when the width of the blade exceeds 0.5 times the outer diameter of the pile main body, the resistance received by the blade surface increases, so that the pile main body is difficult to rotate when penetrating. In addition, since the range of loosening the ground around the pile body is expanded, the frictional force received from the ground after penetrating the pile body is reduced, and the reaction force against the horizontal force that the pile receives during an earthquake is less likely to be received from the ground. May be less stable.

  On the other hand, if the width of the blade is in the range of 0.01 to 0.5 times the outer diameter of the pile main body, the penetration workability of the pile is improved, so that the pile penetration work is facilitated. Moreover, since the range which loosens the ground around a pile main body at the time of penetration is not expanded and the distance between the outer peripheral surface of a pile main body and a hole wall can be suppressed after penetration, it is easy to obtain a peripheral friction force from the ground. In addition, the horizontal force due to the earthquake or the like that the pile receives from the upper structure is transmitted to the ground, and it is easy to receive a reaction force from the ground, so a resistance force against the horizontal force is ensured.

  The part above the tip of the blade works to restore the soil on the hole wall by sending the soil cut by the tip to the upper part of the blade as the pile body rotates and penetrates (pushing up) and pressing it against the hole wall. Therefore, the length of the blade is determined so that this function is effectively exhibited.

  For example, if the length of the blade is less than 0.04 times the circumference of the pile body, the effect of scooping up the cut earth and sand is hardly exhibited. On the other hand, when a plurality of blades project from the pile body, if the length of one blade exceeds 0.5 times the circumference of the pile body, it is the same as when the blade width is large. The resistance that the blade receives from earth and sand increases.

From the above, when there are a plurality of blades, the length of the blades is suitably in the range of 0.04 to 0.5 times the circumferential length of the pile body as described in claim 6 . When a plurality of blades are protruded, the blade does not go around the pile body because the length of one blade is 0.5 times or less the circumferential length of the pile body. When there is one blade, the length of the blade exceeds 0.5 times the circumference of the pile body, and the pile body may circulate. The length of the blade refers to the length before or after the projecting to the pile body.

  If the length of the blade is in the range of 0.04 to 0.5 times the circumference of the pile body, the blade tip cuts up the earth and sand once while suppressing the resistance when the pile body penetrates. After that, the blade can be dropped from above the blade and pressed against the hole wall.

The tip open type ready-made pile according to any one of claims 1 to 7 is formed by connecting an excavation head constituting a part of the tip end side and a pile body of the ready-made pile as described in claim 8 . Is also produced. The excavation head is joined to both the inner pipe, the outer pipe having a diameter shorter than the inner pipe and larger than the diameter of the inner pipe, and straddling between the tip of the inner pipe and the tip of the outer pipe. A ring steel plate formed into a truncated cone shape, the pile body side between the inner pipe and the outer pipe is opened, and the pile body is inserted into a gap between the inner pipe and the outer pipe. The blade is projected from the inner peripheral surface of the inner tube through the ring steel plate to the outer peripheral surface of the outer tube. The blade continues spirally from its tip to the outer peripheral surface of the outer tube, which is the outer peripheral surface of the pile body.

The pile body side between the inner pipe and the outer pipe of the excavation head is opened, and the ready-made pile that is the pile body is inserted into the gap between the inner pipe and the outer pipe, and the excavation head and the pile main body are integrated. To do. The excavation head according to claim 8 has a double pipe structure of an inner pipe and an outer pipe, and a space is secured between the inner pipe and the outer pipe by a ring steel plate, so that it is mainly combined with a ready-made concrete pile. Combination with steel pipe piles is also possible. When the pile main body is a ready-made concrete pile, the excavation head and the pile main body are integrated by, for example, welding an outer tube to a band plate fixed for a joint around the tip of the ready-made concrete pile.

In claim 8 , the excavation head is manufactured separately from the pile main body, and is connected to the pile main body to constitute an open-ended pre-made pile. Therefore, the thickness (pipe thickness) of the pile main body is the inner pipe of the excavation head If it is equal to the distance between the outer pipe and the outer pipe, it can be freely combined with existing ready-made concrete piles and steel pipe piles having different lengths. Therefore, the excavation head can give a function of penetration to a ready-made pile that cannot penetrate into the ground alone, and contributes to expanding the use of the ready-made pile.

According to claim 8 , the ring steel plate on which the blade protrudes is inclined with respect to the penetration direction of the pile body, so that the ring steel plate removes the earth and sand cut by the blade from the center of the hole to the hole wall side. It has a function. The earth and sand cut by the blade tends to move from the hole bottom to the hole wall as the excavation head rotates due to the inclination of the ring steel plate. In other words, the ring steel plate places earth and sand on the blade from the bottom of the hole and acts to encourage the blade to press the earth and sand against the hole wall, making it easier to keep the blade always in contact with the bottom of the hole. Increases efficiency. In addition, since the effect of pressing the earth and sand against the hole wall is also increased, the frictional force received from the hole wall is also increased, and the stability of the pile body due to the frictional force after penetrating the pile body is improved.

  The blade projecting on the outer peripheral surface of the pile body tip continues from the tip position of the pile body to the outer surface, so that the earth and sand cut by the blade tip is moved to the upper surface of the blade along with the excavation by rotation of the pile body. Therefore, the blade does not receive resistance from the earth and sand in the ground, and the penetration of the pile body is improved.

  In addition, the tip of the blade straddles the outer peripheral surface and inner peripheral surface of the pile body, cutting the earth and sand present on the outer peripheral side and inner peripheral side of the pile main body, and the resistance received by the outer peripheral surface and inner peripheral surface of the pile main body Since it can reduce, the penetration of the pile main body into the ground can be helped.

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

  In FIG. 1, one or a plurality of blades 3 inclined with respect to the material axis of the pile main body 2 are projected on the outer peripheral surface of the tip end of the pile main body 2, and the tip 3 a of the blade 3 is An open-ended ready-made pile (hereinafter referred to as “piles”) that protrudes from the tip position of the pile body 2 to the excavation side across the outer peripheral surface and the inner peripheral surface, and the blade 3 is spirally continuous from the tip portion 3a to the outer peripheral surface of the pile body 2 A specific example of 1 is shown.

  A steel pipe is mainly used because the blade 3 protrudes from the pile body 2. For example, if the anchor is formed on the blade 3 and the anchor can be embedded in the concrete, the pile body 2 is attached to the pile body 2. It may be molded with concrete piles (prestressed concrete piles (PHC piles)). When the pile main body 2 is a concrete pile and the blade 3 is protruded by welding, it is sufficient that at least the section where the blade 3 protrudes is made of steel out of the entire length of the pile main body 2. In some cases, a steel plate is wound around the outer peripheral surface of the tip portion of 2.

  As shown in FIGS. 1-4, the front-end | tip part 3a of the braid | blade 3 straddles the outer peripheral side and inner peripheral side of the pile main body 2 front end, and is a bowl shape which pinches | interposes the pile main body 2 front end, The outer peripheral side of the pile main body 2 in it The main body portion 3b of the blade 3 continues in a spiral shape from the portion located at, and is integrated with the outer peripheral surface of the pile body 2 by welding or the like. The tip 3a of the blade 3 projects from the tip position of the pile body 2 to the penetration side, thereby functioning as a claw for excavating (cutting) the ground.

  In the drawing, when the pile body 2 rotates clockwise with respect to the material axis, the blade 3 protrudes in a spiral shape so that the blade 3 enters the ground, but the direction of the spiral of the body portion 3b is not limited. In some cases, the direction is reversed. 3 and 4 are three-dimensional views of the side surface of the pile 1 shown in FIG.

  In the drawing, three blades 3 are equally arranged in the circumferential direction of the pile body 2, but the number of the blades 3 is arbitrary. For example, one blade 3 that spirals around the pile body 2 is arranged. May be placed. The blade 3 is basically formed of a single plate, a flat bar or the like, but may be formed by combining a plurality of plates or the like.

  The main body 3b of the blade 3 is bent or curved upward at an intermediate portion in the length direction, and the inclination angle with respect to the material axis of the pile main body 2 or the horizontal plane is different across the position of the intermediate portion. As shown in FIG. 1, the inclination angle α2 with respect to the upper horizontal plane across the intermediate portion of the main body 3b is smaller than the inclination angle α1 with respect to the lower horizontal plane, and the main body 3b is placed on the main body 3b as the pile main body 2 rotates. The adhesion of the earth and sand to the main body 3b is cut, and the earth and sand are easily dropped from the main body 3b.

  The main body 3b of the blade 3 is twisted to the hole wall side from the side closer to the tip 3a to the upper side on the side away from the outer peripheral surface of the pile main body 2 (hole wall side). When viewed in the circumferential direction, the hole wall is bent or curved in the width direction so as to be convex.

  In FIG. 1, the portion above the middle portion of the main body 3b is twisted, but twisting may be introduced from the portion near the tip 3a. The portion twisted toward the hole wall side of the main body portion 3b facilitates the fall of the earth and sand placed on the main body portion 3b, and the earth and sand dropped from the main body portion 3b is moved to the hole wall as the pile main body 2 rotates. It works to push.

  When the main body 3b of the blade 3 is twisted from the side closer to the tip 3a to the upper side, the main body 3b is formed when the blade 3 is formed from a single plate having a constant width. The protrusion width from the outer peripheral surface of the pile main body 2 gradually decreases from the tip 3a side upward.

  Due to the gradual reduction of the protruding width, the earth and sand placed on the main body portion 3b are difficult to maintain when the pile main body 2 is rotated, and are easily dropped. When the blade 3 is composed of a single plate having a variable width, or formed from a plurality of plates in the width direction, the protruding width may be constant.

  When the projecting width of the blade 3 gradually decreases, the distance between the portion where the projecting width decreases and the hole wall becomes smaller, so the frictional force that the blade 3 receives from the hole wall during the rotation of the pile 1 is reduced. Is done. Since the resistance at the time of penetration of the pile 1 is reduced by reducing the frictional force, the pressure required for the penetration of the pile 1 does not increase, and the motor 6 equipped in the pile driving machine 4 does not require high power. There is.

  FIGS. 5A and 5B show a state when the pile main body 2 (pile 1) integrated with the blade 3 is penetrated into the ground. As shown in FIG. 1, the width W of the tip 3 a of the blade 3 is 0 of the outer diameter D of the pile body 2 from the relationship of ensuring the stability of the pile 1 after penetration while ensuring the penetration workability of the pile 1. For example, if the outer diameter D of the pile body 2 is 600 mm, the width W of the blade 3 is about 6 to 300 mm. In particular, an appropriate range of the width W of the blade 3 tip 3a is about 1.2 to 1.8 times the tube thickness t of the pile body 2. For example, if the tube thickness t is 9 mm, the blade 3 tip 3a The width W is preferably about 11 mm to about 16 mm. The protruding length of the blade 3 tip 3a from the tip of the pile main body 2 varies depending on the properties of the ground, but may be about 10 to 60 mm regardless of the outer diameter D of the pile main body 2 or the like.

  Further, the length (peripheral length) L of one blade 3 along the peripheral surface of the pile body 2 is based on the relationship in which the plurality of blades 3 exerts the effect of scooping up earth and sand and then pressing the hole wall. When the outer diameter D of the pile body 2 is 600 mm within the range of 0.04 to 0.5 times the circumferential length R (πD) of the pile body 2, the length L of the blade 3 is about 80 to 940 mm. become. In relation to the outer diameter D of the pile body 2, the optimum range of the length L of the blade 3 is about 0.3 to 1.0 times the outer diameter D. If the outer diameter D of the pile body 2 is 600 mm, the range of the length L of the blade 3 is preferably 200 to 600 mm, and if the outer diameter D is 300 mm, 100 to 300 mm is preferable.

  As shown in FIG. 7, the pile 1 is suspended from the arm 5 of the pile driving machine 4 and is penetrated into the ground by applying pressure downward in the vertical direction while being rotated by the motor 6. For the pile 1, for example, a wire 7 is stretched along the material axis direction inside and outside the pile 1, and the both ends of the wire 7 are pulled by using the weight of the pile driving machine 4 as a reaction force. Is pressed into the ground along the leader 8. FIG. 7- (a) shows the construction procedure when the ground level is located above the pile driving machine 4 and (b) is located below.

  FIG. 6 shows the situation of the tip of the pile 1 in the ground. By rotating the pile 1, the tip 3a of the blade 3 protruding from the tip of the pile body 1 cuts the ground, and the pile 1 penetrates into the cut hole. Since the drilling hole is formed at the position of the tip 3a of the blade 3 as shown in FIG. 5- (a), the pile 1 descends in the ground that has been cut, and earth and sand are not clogged in the pile body 2. .

  As shown in FIG. 5- (a), the ground cutting width w by the tip portion 3a of the blade 3 is a size obtained by adding a displacement due to swinging at the time of penetration of the pile 1 to the width W of the tip portion 3a. Yes, the diameter of the excavation hole required for penetrating the pile 1 is kept to a minimum, and it is not necessary to form an excavation hole having a diameter larger than necessary.

  The earth and sand cut by the tip portion 3a of the blade 3 is once placed on the main body portion 3b of the blade 3 and relatively sent to the upper portion of the main body portion 3b as the pile 1 is dug. Or, since it is bent or curved in the width direction, it is dropped from the main body 3b after being sent upward. The earth and sand that has fallen from the main body 3b is pressed against the hole wall by the blade 3 that passes under the sand and sand as the pile 1 is bent because the main body 3b is bent or curved in the width direction. The loosened hole wall is repaired and hardened.

  Since the protrusion width of the main body 3b of the blade 3 from the pile main body 2 gradually decreases as described above, the resistance at the time of penetration of the pile 1 decreases, so the pile 1 penetrates into the excavation hole. It is easy. On the other hand, as shown in FIG. 6, at the time of completion of penetration when the tip 3 a of the blade 3 reaches the support layer, the sediment on the hole wall above the tip of the pile body 2 is consolidated in the radial direction of the hole wall. The frictional force of the entire pile 1 received from the hole wall is increased, and the supporting force by the circumferential frictional force is increased accordingly.

  FIG. 8 shows a manufacturing example of the pile 1 in which a plurality of blades 3 and a plurality of cutting claws 31 are projected from the tip of the pile body 2 in order to enhance the ground cutting effect. Here, the pile body 2 is manufactured from two inner pipes 21 and outer pipes 22 having different diameters and lengths, and a ring steel plate 23 formed in a truncated cone shape straddling between the tips of both pipes 21 and 22. In this case, the pile 1 has a double pipe structure.

  In the case of FIG. 8, steel pipes are mainly used for the inner pipe 21 and the outer pipe 22, but the pile 1 can also be molded as a concrete pile filled with concrete between the inner pipe 21 and the outer pipe 22. Although FIG. 8 shows a case where three blades 3 and three cutting claws 31 are projected, the number of each is arbitrarily set.

  As shown in FIG. 8- (d), the inner tube 21 and the outer tube 22 have the end surfaces of the respective upper ends aligned, the tip of the inner tube 21 having a small diameter and a large length, and the tip of the outer tube 22 having a large diameter. The ring steel plates 23 are welded between the tips of both the tubes 21 and 22. The interval between the inner tube 21 and the outer tube 22 is held by a ring-shaped interval holding member 24 interposed therebetween.

  The blade 3 protrudes so that the tip 3a extends from the inner peripheral surface of the inner tube 26 to the outer peripheral surface of the ring steel plate 28, and the main body 2b protrudes spirally from the ring steel plate 28 to the outer tube 27. . The cutting claw 31 straddles the outer peripheral surface and the inner peripheral surface of the pile body 2 in the same manner as the tip portion 3a of the blade 3, and protrudes from the tip position of the pile body 2 to the excavation side. In the case of FIG. It has a shape straddling between the outer peripheral surface and the inner peripheral surface of the inner tube 21.

  Pile 1 is mainly used for constructing structures such as low-rise buildings such as wooden houses, steel structures, reinforced concrete structures, etc. on ground with low bearing capacity such as landfills and embankments. Used as a pile. In addition, as a foundation and main pillar for slope reinforcement piles, landslide prevention, flood damage prevention, wind and snow prevention, soundproofing / protection nets, etc., as a foundation for traffic lights, street lights, road signs, etc. It is also used as a parent pile for retaining walls after a sediment disaster.

  Since the pile 1 shown in FIG. 8 has a double pipe structure, as shown in (a) and (b), it is used as a retaining wall by cutting out a part of the outer pipe 22 in the circumferential direction. It is also possible to be used as a parent pile for a pile pile. The sheet pile is inserted into the notch portion of the pile 1 from above.

  FIG. 9 shows a manufacturing example of the excavation head 25 in a form in which a part of the front end side of the pile body 2 manufactured from the inner tube 21 and the outer tube 22 and the ring steel plate 23 shown in FIG. Indicates. The excavation head 25 shown here is manufactured from an inner pipe 26 and an outer pipe 27 having different diameters and lengths, and a ring steel plate 28 formed into a truncated cone shape, like the pile main body 2 shown in FIG. The opposite end is open. Steel pipes are used for the inner pipe 26 and the outer pipe 27, and fan-shaped steel sheets are used for the ring steel plates 28.

  Specifically, the excavation head 25 includes an inner tube 26, an outer tube 27 having a diameter shorter than the inner tube 26 and larger than the diameter of the inner tube 26, and between the tip of the inner tube 26 and the tip of the outer tube 27. And a ring steel plate 28 which is joined to both sides and formed into a truncated cone shape, and the blade 3 projects from the inner peripheral surface of the inner tube 26 to the outer peripheral surface of the outer tube 27 through the ring steel plate 28. . The excavation head 25 is combined with a ready-made pile such as a ready-made concrete pile or a steel pipe pile, which is the pile body 2, thereby constituting the open end ready-made pile 1.

  As with the blade 3 of the pile main body 2 shown in FIG. 8, the blade 3 protrudes from the inner peripheral surface of the inner tube 26 to the outer peripheral surface of the ring steel plate 28 so as to protrude from the ring steel plate 28 to the outer tube 27. The main body 2b is projected in a spiral manner. In FIG. 9, the three blades 3 are projected evenly in the circumferential direction, but the cutting claw 31 in FIG. 8 may be projected between the adjacent blades 3, 3.

  The ready-made pile which is the pile body 2 is inserted into the excavation head 25 from the open end as shown in FIG. 9- (b), and is integrated with the excavation head 25 by means such as welding. For example, when the pile main body 2 is a ready-made concrete pile (prestressed concrete pile), since the band plate 2a for the connection with the pile main body 2 to be joined is fixed to both ends of the pile main body 2, this band plate The pile main body 2 and the excavation head 25 are integrated by welding the outer tube 27 of the excavation head 25 to 2a.

  In order to supplement the integration of the pile body 2 and the excavation head 25, ribs 27a are continuously or intermittently provided in the axial direction of the pile body 2 on the inner peripheral surface of the outer pipe 27 as shown in FIG. 9- (b). In addition, the groove 27 may be provided in the outer peripheral surface of the band plate 2a so that the rib 27a enters.

It is the elevation which showed the example of manufacture of the tip open type ready-made pile of this invention. It is a bottom view of FIG. It is the elevation which showed the tip open type ready-made pile shown in FIG. 1 in three dimensions. It is the perspective view which showed the inside of the front end side of the front-end | tip open type ready-made pile shown in FIG. (A) is the longitudinal cross-sectional view which showed the mode at the time of penetration | invasion of the tip open type ready-made pile shown in FIG. 1, (b) is a top view. It is the elevation which showed the mode after penetration | intrusion into the ground of the open end type | mold ready-made pile shown in FIG. (A) Elevated view showing the state of penetration of the open-ended ready-made pile by the pile driver when the ground level is located above the pile driver, (b) is the ground level from the pile driver It is the elevation which showed the mode of penetration when located below. (A) is the perspective view which showed the manufacture example of the pile of a double pipe structure, (b) is the side view of (a), (c) is the end view of the front end side of (b), (d) is the pile of It is sectional drawing cut | disconnected by the surface which passes along an axis | shaft. (A) is the perspective view which showed the manufacture example of the excavation head, (b) is the longitudinal cross-sectional view of (a).

Explanation of symbols

1 ... …… Open-ended ready-made pile 2 ………… Pile body 2a …… Band plate 21 …… Inner tube 22 …… Outer tube 23 …… Ring steel plate 24 …… Spacing retainer 25 …… Drilling head 26 …… Inner Tube 27 …… Outer tube 27a… Rib 28 …… Ring steel plate 3 ……… Blade 3a …… Tip 3b …… Main body 31 …… Cutting claw 4 ……… Pile driver 5 ……… Arm 6 ……… Motor 7 ……… Wire 8 ……… Reader

Claims (8)

The outer peripheral surface of the leading end portion of the pile body, the pile body double several blades inclined with respect to the timber axis is projected,
The blade tip protrudes from the tip position of the pile body to the excavation side across the outer peripheral surface and inner peripheral surface of the pile body,
The blade is spirally continuous from the tip portion to the outer peripheral surface of the pile body , and is bent or curved upward at an intermediate portion in the longitudinal direction of the blade,
It is provided with a pressing piece for pressing the earth and sand cut by the blade against the hole wall, which is formed by being bent or curved gradually downward in the width direction on the upper side across the intermediate portion in the length direction of the blade. Open-ended pile with open end. Of the blade, the portion positioned in the hole wall side with respect to the pile body when viewed the pile body in the circumferential direction, that the hole wall is bent or curved in the width direction so as to project The tip open type ready-made pile according to claim 1 . 3. The tip open type ready-made pile according to claim 2 , wherein the blade has a shape twisted from a position near the tip to an upper end. The tip open type ready-made pile according to any one of claims 1 to 3 , wherein the blade is made of a plurality of blade components divided in the length direction or the width direction. The width | variety of the said blade exists in the range of 0.01-0.5 times the outer diameter of the said pile main body, The tip open | release type ready-made pile in any one of the Claims 1 thru | or 4 characterized by the above-mentioned. The length of the said blade exists in the range of 0.04-0.5 times the circumference of the said pile main body, The tip open type ready-made pile in any one of Claim 1 thru | or 5 characterized by the above-mentioned. The tip open type pre-made pile according to any one of claims 1 to 6 , wherein a plurality of the blades are equally arranged in a circumferential direction with respect to a center of the pile main body. An excavation head constituting a part of the tip end side of the tip open type ready-made pile according to any one of claims 1 to 7 ,
An inner tube, an outer tube having a diameter shorter than the length of the inner tube and larger than the diameter of the inner tube, and a junction between both ends of the inner tube and the outer tube. With a ring steel plate molded into
The pile main body side between the inner pipe and the outer pipe is opened, and the pile main body is inserted into a gap between the inner pipe and the outer pipe,
The open-ended pile excavation head for an open-ended pile, wherein the blade projects from the inner peripheral surface of the inner pipe to the outer peripheral surface of the outer pipe through the ring steel plate.

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