JP2005171616A - Rotary penetration pile and its work-execution method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary penetration pile and its work-execution method having high penetration performance into the ground, and superior in support performance and economic efficiency. <P>SOLUTION: Two blades 2 having an inner diameter smaller than an inner diameter of a hollow pile 1 and having an outer diameter larger than an outer diameter of the hollow pile 1, are installed on a tip surface 3 of the hollow pile 1 by welding. A surface of the respective blades 2 forms about the half periphery of a weight surface expanding to the pile tip side. In construction, the hollow pile 1 is pressed in the ground while rotating. The tip of the hollow pile 1 forms the opening end. When rotatingly penetrating the hollow pile 1, sediment is taken inside the hollow pile 1. Since the surface formed of the blades 2 is the weight surface, the penetration performance is improved, and cross-sectional performance to vertical directional force is also enhanced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a rotary penetrating pile with wings that can rotate and penetrate into the ground, and a construction method thereof.

  Conventionally, various steel pipe piles that can be rotated and penetrated have been developed in which flat or spiral wings are provided on the tip or the outer periphery of the tip.

  For example, Patent Document 1 describes a structure in which a wing made of two or three fan-shaped flat plates is attached by cutting out the tip of a pile spirally.

  Patent Document 2 describes a rotary penetrating pile on the outer peripheral surface of the tip of a hollow pile wound with a curved spiral blade.

  In Patent Document 3, the tip of the steel pipe is cut out in a spiral shape, and the outer diameter is 1.5 to 3 times the outer diameter of the steel pipe pile, and the inner diameter is 0.4 to 0.9 times the inner diameter of the steel pipe pile. The one with a spiral wing attached is described.

In addition, Patent Document 4 describes a structure in which a frustoconical bottom-up support wing is provided on the outer peripheral portion of a small-diameter steel pipe in order to ensure a large support force and suppress initial settlement.
Japanese Patent Laid-Open No. 10-102489 JP 2001-077332 A JP 2001-193063 A JP 2002-221947 A

  For winged piles that are rotated and penetrated, we expect an improvement in the tip support force by the wing part, and a high support force is obtained, the penetration is good, the strength of the wing is sufficient, and the economy It is required to be excellent.

  Therefore, it is described in the above-mentioned Patent Document 1 that the step of the spiral blade attachment portion is defined within a predetermined range, and in Patent Document 3, the outer diameter is 1.5 to 3 times the outer diameter of the steel pipe. It is stated that by cutting a donut-shaped steel plate with an inner diameter of 0.4 to 0.9 times to form a spiral wing and by defining the mounting position, it has excellent penetration and high support force. ing.

  However, when the spiral wing is formed from a flat plate, if the outer diameter of the wing is increased in order to obtain a high supporting force, the penetrability is deteriorated, and the resistance from the ground and the proof strength of the wing against the supporting force become problems. For this reason, if the thickness of the blade is increased, all the requirements cannot be satisfied as the penetration becomes worse and the economic efficiency is also impaired.

  In addition, when the blade is installed at the tip of the steel pipe, the penetrability is good, but it is difficult to penetrate straight, and the stability with respect to the supporting force after the penetration tends to be problematic. On the other hand, when the spiral wing is attached at a predetermined interval from the tip, stability is easily obtained, but there is a problem that the penetrability is poor.

  On the other hand, the invention described in Patent Document 2 is expected to improve the bending rigidity of the wing by bending the wing. However, since the wing is attached to the outer peripheral surface of the hollow pile, the wing attachment position is large. There is a problem that a bending moment acts, and there is a problem that workability deteriorates when earth and sand are clogged between wound wings and pile circumference.

  Further, the invention described in Patent Document 4 is expected to improve the supporting force and stability by the frustoconical bottom expansion support wing, and the bottom expansion support wing is provided on the outer periphery of the pile. Since there is no cut or notch, all of the sediment below the wing must pass upward from the narrow discharge port, which causes a serious problem in penetration.

  The invention of the present application provides a rotary penetrating pile that has been devised in the wing shape based on the background as described above, has high penetrability into the ground, and is excellent in supporting performance and economy, and its construction method. It is an object.

  The rotary penetrating pile according to claim 1 of the present application has a plurality of blades having an inner diameter smaller than an inner diameter of the hollow pile and an outer diameter larger than the outer diameter of the hollow pile on a front end surface of the hollow pile. Each of these forms a substantially conical surface or a part of a substantially polygonal conical surface extending to the pile tip side.

  Hereinafter, in order to simplify the description, a substantially conical surface, a polygonal conical surface, or a part thereof will be described as a “conical surface”.

  As a typical form of the invention according to claim 1, in the case where there are two blades of the rotary penetrating pile, each blade is substantially semicircular in the circumferential direction of the pile, and the surface of each blade forms a conical surface. A form is mentioned.

Since the surface of the spiral wing of a conventional rotary penetrating pile is on a flat surface, the proof strength of the wing is related to the resistance or supporting force from the ground. Is controlled by the coefficient (b · t ² ) / 6 (t is the plate thickness, b is the width, but in this case, the width b should be considered in any direction of the wing in terms of resistance from the ground or bearing capacity. Can do that.)

  In the case of the present invention, since the plate constituting the wing has a conical surface as a whole (including the case of forming a conical surface as a whole by joining a plurality of divided flat plates). With respect to the resistance or supporting force from the ground, the section modulus is greatly improved as compared to the case of a flat surface, and the plate thickness for obtaining the same section performance is reduced, the economy is improved, and the penetration is also improved.

  In addition, the bearing capacity of the ground depends on the shear strength near the wing at the tip of the pile, and in the case of unconsolidated sand and gravel, a confining effect is obtained by the shape of the wing that forms a conical surface. Supporting force is improved.

  Furthermore, the wing end is positioned below the tip of the pile, making it easier to penetrate the pile, and the other end of the wing is horizontal (vertical to the pile) or above it, propulsive force is increased. improves.

  In addition, the wing is attached not to the outer peripheral surface of the hollow pile, but to the tip surface, the inner diameter side of the wing is located inside the inner diameter of the hollow pile, and the outer diameter side of the wing is positioned outside the outer diameter of the hollow pile. Therefore, the bending acting on the attachment position is small with respect to the resistance in the vertical direction from the ground, and the stability of the blade attachment portion is higher than when the blade is attached to the outer peripheral surface.

  The rotary penetrating pile according to claim 2 of the present application has a plurality of blades having an inner diameter smaller than an inner diameter of the hollow pile and an outer diameter larger than the outer diameter of the hollow pile on a front end surface of the hollow pile. Each has a conical surface (substantially a conical surface or a part of a substantially polygonal conical surface) extending to the rear end side of the pile.

  The plates that make up the wings have a conical surface as a whole, and the section modulus is significantly improved with respect to the resistance or bearing force from the ground compared to a flat surface. This is the same as the invention according to claim 1 in that the point is improved and the stability of the blade attachment portion is high.

  In the invention according to claim 2, the direction in which the conical surface spreads is opposite to that of the invention according to claim 1, and the tip supporting force as a pile is slightly inferior to that of the invention according to claim 1, but in the ground Has a downward conical shape or a polygonal pyramid shape, and therefore the penetrability is better than that of the invention according to claim 1.

  What is necessary is just to select the rotation penetration pile concerning these Claims 1 and the rotation penetration pile concerning Claim 2 according to the ground conditions, design conditions, etc. which are related to the obtained support force and penetration property.

  According to a third aspect of the present invention, in the rotary penetrating pile according to the first or second aspect, the tip surface of the hollow pile to which the plurality of wings are attached is inclined in one direction around the pile axis together with each wing. It is a feature.

  In consideration of penetration by rotational penetration, it is desirable that each blade be inclined in a spiral direction, for example. The conical surface formed by the plurality of wings does not have to be a single one, and includes cases where each conical surface forms another conical surface. In addition, it is necessary to process the front end surface of a hollow pile by notching etc. according to the attachment position of each wing | blade.

  For example, if two wings are arranged on a spiral that is shifted by half a circle, the wings can be symmetrical or nearly symmetrical with respect to the plane including the pile axis. The stability is also high in terms of performance. The case where there are three or more wings can be considered as in the case where there are two wings.

  Further, each wing is not required to be mounted on the spiral as described above. For example, in the case of mounting two wings, a member that forms a frustoconical surface is simply 2 A wing having a split shape may be attached to the tip of the pile so that the inclination directions are alternate.

  According to a fourth aspect of the present invention, in the rotary penetrating pile according to the first, second, or third aspect, the tip of the hollow pile is opened on the inner diameter side of the plurality of blades.

  In the present invention, the wing is attached to the tip surface of the rotary pile, but by opening the inner diameter side of the wing, the earth and sand can be taken into the hollow pile at the time of rotation penetration, Construction of low soil removal can be performed efficiently.

  The construction method of the rotation penetration pile which concerns on Claim 5 of this application is penetrated in the ground, if the rotation penetration pile which concerns on Claim 1, 2, 3 or 4 is rotated around a pile axis | shaft. Is.

  The rotary penetrating piles according to claims 1 to 4 are provided with a plurality of wings on the tip surface for rotary penetrating into the ground, and can be constructed by the same method as conventional rotary penetrating piles. It can be used mainly for non-polluted construction.

  According to the invention according to claim 1 of the present application, by forming the conical surface in which the wing attached to the tip surface of the pile spreads downward, the penetration into the ground can be improved and the workability can be improved. .

  Moreover, the cross-sectional performance of the blade with respect to the force in the vertical direction is improved, and a large proof stress is obtained. When the same proof strength is obtained, the blade thickness can be reduced. Since the wing is attached to the tip of the pile, the mounting stability is high.

  In addition, since the wings are not in the same plane, the wings do not slip at the position where the layer changes, and the angle of the blade tip is larger than that of a flat plate or spiral plate, so the penetration performance is improved and the cobblestone is gathered in the center and the steel pipe The performance of taking in is improved.

  Since the surface of the wing that contacts the ground is a conical surface that spreads downward, the support force can be improved by the confining effect.

  According to the invention according to claim 2 of the present application, the penetration into the ground is further enhanced by forming a conical surface in which the wing attached to the pile spreads upward, and similar to the invention according to claim 1 The cross-sectional performance of the wing against vertical force is improved and the mounting stability is high.

  In the invention which concerns on Claim 3, resistance of rotation penetration decreases further, and stability is high also in terms of the penetration property at the time of construction, and the support performance after construction by arrange | positioning a wing | blade symmetrically.

  In the invention which concerns on Claim 4, at the time of rotation penetration, earth and sand can be taken in in a hollow pile from the opening part of the internal diameter side of a wing | blade, and construction of non-exhaust soil or low soil removal can be performed more efficiently.

  According to the invention according to claim 5 of the present application, the rotary penetrating piles according to claims 1 to 4 are rotationally penetrated into the ground. Therefore, compared with conventional pile construction by rotary penetration, the penetrability is high and the workability is improved. Can be planned.

  1 and 2 show an embodiment of a rotary penetrating pile according to claim 1 of the present application. In this example, two blades 2 are provided on the tip surface 3 of the hollow pile 1.

  Each blade 2 has a shape in which the steel material forming the truncated cone-shaped conical surface is substantially divided into two, and is inclined so as to intersect the notched pile tip surface 3 when viewed from the side. Welded. In addition, a blade-like excavation blade 5 is provided on the leading side of each blade 2 at the time of rotation penetration so that the rotation penetration becomes smooth.

  In construction, the hollow pile 1 is press-fitted while rotating in the direction indicated by the arrow in FIG. Moreover, in this example, the inner part surrounded by the wing | blade 2 of the front-end | tip of the hollow pile 1 is an open end, and earth and sand are taken in into the inside of the hollow pile 1 from the opening part 4 in the rotation penetration of the hollow pile 1. , The penetration resistance is alleviated.

  In a conventional winged pile of the same type as shown in Patent Document 1 listed in the section of the prior art, the surface formed by the wing is a plane, whereas the surface formed by the wing 2 as in the present invention. Since it becomes the weight surface, the penetration performance can be improved, the workability can be improved, and the cross-sectional performance with respect to the force in the vertical direction can be improved. Wings can provide greater yield strength.

  Further, since the surface of the wing 2 in contact with the ground is a conical surface that extends downward, it is possible to improve the supporting force by the above-described confining effect.

FIG. 2D schematically shows the relationship between the blade attachment angle θ ₁ and the spread angle θ ₂ in this embodiment, and the relationship between θ ₁ and θ ₂ is θ ₂ = 180 ° −2θ. ₁

  FIG. 3 is a diagram illustrating a case where the outer peripheral end of one end portion of the wing is above a plane perpendicular to the axial direction of the pile at a connection position between the end portion and the pile.

  FIG. 4 shows an embodiment of a rotary penetrating pile according to claim 2 of the present application. Each blade 2 is manufactured by welding four steel plates having an arcuate outer periphery by welding, and forms an approximately half circumference (approximately 180 °) of an octagonal conical surface that is nearly a cone extending to the pile tip side. ing.

  The major difference from the rotary penetrating pile according to claim 1 is the spreading direction of the weight surface formed by the surface of the wing 2, which is spread to the pile rear end side, contrary to the case of claim 1.

  The sectional performance with respect to the force in the vertical direction is in principle the same as in the case of claim 1, and a larger section modulus can be obtained compared to a conventional blade spread in a plane.

  However, there is no confining effect as in the invention according to claim 1. On the other hand, since the diameter at the front end side of the pile is small, the penetrability is better than the case of the invention according to claim 1.

  By pressing the hollow pile 1 while rotating it in the direction indicated by the arrow in the figure, it is rotated and penetrated into the ground as in the case of the invention according to claim 1 shown in FIGS.

It is a perspective view of the pile front-end | tip part which shows one Embodiment of the rotation penetration pile which concerns on Claim 1 of this application. Fig. 1 shows the details of the rotary penetrating pile shown in Fig. 1. (a) is a front view, (b) is a side view, (c) is a bottom view, and (d) is a cross-sectional view along line AA in (a). is there. It is a side view of the pile front-end | tip part which shows other embodiment of the rotation penetration pile which concerns on Claim 1 of this application. It is a perspective view of the pile front-end | tip part which shows one Embodiment of the rotation penetration pile which concerns on Claim 2 of this application.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hollow pile, 2 ... Wing, 3 ... Tip surface, 4 ... Opening part, 5 ... Excavation blade

Claims (5)

  The front end surface of the hollow pile has a plurality of wings whose inner diameter is smaller than the inner diameter of the hollow pile and whose outer diameter is larger than the outer diameter of the hollow pile, and each of the plurality of wings has a substantially conical surface extending to the pile front side or Rotating penetrating pile characterized by being part of a polygonal pyramid surface.   The front end surface of the hollow pile has a plurality of wings whose inner diameter is smaller than the inner diameter of the hollow pile and whose outer diameter is larger than the outer diameter of the hollow pile. Or the rotation penetration pile characterized by having comprised a part of polygonal cone surface substantially.   The rotary penetrating pile according to claim 1 or 2, wherein a tip end surface of the hollow pile to which the plurality of blades are attached is inclined in one direction around the pile axis together with each blade.   The rotary penetrating pile according to claim 1, 2, or 3, wherein a tip of the hollow pile is opened on an inner diameter side of the plurality of blades. A method for constructing a pile, characterized in that if the rotary penetrating pile according to claim 1, 2, 3 or 4 is rotated around a pile axis, the pile penetrates into the ground.

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