JP5414838B2 - Steel pipe pile, composite pile and composite pile manufacturing method - Google Patents

Description

  In particular, the present invention relates to a steel pipe pile used for ground improvement of a low-rise building structure, a steel pipe soil cement composite pile constructed in the ground including the steel pipe pile, and a method for manufacturing the composite pile. .

  A super mini drill (SMD) pile construction method is known as a steel pipe pile construction method suitable for ground improvement of medium- and low-rise buildings. The SMD pile construction method is a construction method in which a steel pipe pile having a spiral wing (outer wing) having a size of about 2 to 3 times the pile diameter is attached to the outer periphery of the rake tip by rotating clockwise. The penetration of the steel pipe pile is rotationally penetrating into the ground part in an undrained state because the outer wing receives a propulsive force from the ground by giving a rotational torque to the pile head. Moreover, the SMD pile construction method has a feature that cement milk is not used.

  Further, a deep layer mixing (CDM) method is known in which a cement-based solidifying material slurry and an in-situ soil are stirred and mixed in a soft ground using a processing machine and solidified to a predetermined strength. The improved piles formed by the CDM method are called column-solidified piles or soil cement columns, and are used for improving the foundation ground of various structures, as well as temporary structures such as retaining walls and securing ground stability during excavation. There are also uses.

  On the other hand, steel pipe piles have a problem that as the years pass, rust is generated on the steel pipe surface and the initial strength cannot be maintained. Moreover, the conventional steel pipe pile has the problem that the trajectory through which the spiral blade at the tip has passed remains a gap, and the frictional force around the circumference of the pile diameter is reduced, and a void is generated in the ground around the pile. On the other hand, columnar solidified piles are not as strong as steel pipe piles, and there is a problem that the pile diameter of the solidified piles is increased in order to impart strength. As a solution to such a problem, a steel pipe soil cement composite pile in which a soil cement is formed around the steel pipe pile is known. Since the composite pile has an alkaline cement around the steel pipe, it prevents rust on the surface of the steel pipe and maintains the initial pile strength. Moreover, since the core material of a composite pile is a steel pipe, since the whole pile strength becomes high, the whole pile diameter can be made small.

  As such a steel pipe soil cement composite pile, a steel pipe soil cement composite pile using a steel pipe in which concave grooves forming stripes at regular intervals on the outer periphery of the steel pipe as a core material of the soil cement pile is known ( JP 2007-191990 A). When constructing a composite pile disclosed in Japanese Patent Application Laid-Open No. 2007-191990, excavation and agitating rods are used to inject a solidifying agent such as cement milk from the tip, and the soil and the solidifying agent are mixed and stirred to form soil cement. Then, a steel pipe is inserted and embedded in the uncured soil cement.

JP 2007-191990 A (Claim 1, paragraph number 0010)

  However, since the construction method of the composite pile described in JP 2007-191990A inserts and embeds the steel pipe in uncured soil cement, is it almost impossible to install the steel pipe at the center of the composite pile? In order to install in the center, many processes are required, and there is a problem that an increase in cost is inevitable. Moreover, the steel pipe at the center does not reach the tip of the composite pile, but stops and is buried in the middle. For this reason, since the conventional composite pile cannot be embedded in the hard ground of a steel pipe, there is a problem that it does not function as a support pile but only functions as a friction pile.

  Accordingly, an object of the present invention is to provide a composite pile that functions as a support pile, to provide a construction method for a composite pile that can correctly install a steel pipe at the center of the composite pile, and to be used for it. It is to provide a steel pipe pile having a new structure.

In such a situation, the present inventors have conducted intensive studies, and as a result, the outer peripheral surface of one end portion in the axial direction of the hollow steel pipe has a spiral shape with an inclination angle α ₀ with respect to the direction perpendicular to the axial direction of the steel pipe. If a steel pipe pile that forms one or more second blades having an inclination angle α _n different from the inclination angle α ₀ on the outer peripheral surface above the first blade is provided to the hard ground It is found that a support pile can be obtained by enabling the rooting construction of the steel, and that a steel pipe can be correctly installed at the center of the composite pile by a simple method of gravity flow of the solidified material, and the present invention is completed. It came to.

That is, according to the present invention, a spiral first blade is attached to the outer peripheral surface of one end portion in the axial direction of a hollow steel pipe at an inclination angle α ₀ with respect to a direction perpendicular to the axial direction of the steel pipe. the outer peripheral surface of the upper first blade, the inclination angle alpha ₀ and are those in which the second blade to form one or more stirring or disturb the soil having different tilt angles .alpha.x, the second blade directly above the first blade the inclination angle is to provide a steel pipe, which is a larger than the inclination angle alpha _0.

In the present invention, a spiral first blade having a vertical length H ₀ between the start point and the end point of the blade is attached to the outer peripheral surface of one end portion in the axial direction of the hollow steel pipe. One or more second blades that stir or disturb the ground having a vertical length Hx between the start point and the end point of the blades different from H ₀ are formed on the upper outer peripheral surface, immediately above the first blades. The length in the vertical direction between the start point and the end point of the blades of the second blades is greater than H ₀ , thereby providing a steel pipe pile.

  The present invention also provides a composite pile comprising the steel pipe pile and a soil cement formed around the outer peripheral surface of the steel pipe pile.

  Moreover, this invention provides the manufacturing method of the composite pile characterized by having the process of supplying the solidification material around the steel pipe of this steel pipe pile, penetrating the said steel pipe pile in the ground by normal rotation. is there.

  According to the steel pipe pile of the present invention, since the orbit of the second blade enters various directions different from the first blade with respect to the ground around the steel pipe, the ground can be greatly disturbed. Moreover, since the 2nd blade | wing is a different shaped blade | wing different from a 1st blade | wing, the pressing force to a downward direction and a horizontal direction increases, and the consolidation effect to a lower ground and a surrounding ground respectively becomes large. Moreover, the steel pipe pile of this invention can be manufactured only by bolting the blade | wing which newly welded the 2nd blade | wing or the components to well-known steel pipe piles, such as the conventional SMD pile.

  Moreover, according to the composite pile of this invention, since the front-end | tip of a steel pipe can be rooted in hard ground, it has both functions of a friction pile and a support pile. Moreover, since a steel pipe pile is located in the center of a composite pile, stable support strength can be expressed. Moreover, since the steel pipe pile circumference is alkaline cement, the corrosion prevention effect of a steel pipe is high.

  Further, according to the composite pile manufacturing method of the present invention, in addition to the same effect as the steel pipe pile described above, a simple method of rotating the steel pipe pile while introducing the solidified material from the ground surface around the steel pipe, It is possible to manufacture composite piles in which steel pipes are correctly arranged.

It is a fragmentary perspective view of the steel pipe pile in the 1st Embodiment of this invention. It is a side view of the steel pipe pile of FIG. It is a simplification figure of the steel pipe pile in the 2nd Embodiment of this invention. It is a simplification figure of the steel pipe pile in the 3rd Embodiment of this invention. It is a figure explaining a partial spiral blade. It is a figure explaining another partial spiral blade. It is a figure explaining another spiral blade. It is a simplified diagram explaining the manufacturing method of the composite pile in embodiment of this invention. FIG. 9 is a simplified diagram for explaining a process following the process of FIG. 8. FIG. 10 is a simplified diagram for explaining a process following the process of FIG. 9.

(Description of steel pipe pile)
In the steel pipe pile of the present invention, a spiral first blade is attached to the outer peripheral surface of one end portion in the axial direction of the hollow steel pipe at a tilt angle α ₀ with respect to a direction perpendicular to the axial direction of the steel pipe. One or more second blades having an inclination angle α _x different from the inclination angle α ₀ are formed on the outer peripheral surface above the blade.

In the present invention, the first blade is a spiral blade and may be the same as the tip blade of a conventional SMD pile, and examples thereof include a regular spiral blade and an irregular spiral blade. By making the first blade spiral, it is possible to bite into the ground and facilitate the penetration of the steel pipe pile into the ground. A regular spiral blade is a spiral blade of one or more turns, and has the same inclination angle α ₀ at all positions of the spiral blade. For example, as shown in FIG. 7, the non-regular spiral blade does not have the same inclination angle α ₀ at all the positions of the spiral, but includes a blade including a horizontal portion 331 or a gently inclined portion. say. In the present invention, when the spiral blade is defined by the inclination angle, the regular spiral blade and the blade corresponding to the regular spiral blade are targeted. The blades corresponding to the regular spiral blades are the partial spiral blades 31A and 32A shown in FIG. 5 and FIG. 6, and a part of the regular spiral blades is omitted. It becomes a blade.

The inclination angle α ₀ of the spiral of the first blade is preferably 5 to 52 degrees. When the inclination angle α ₀ of the first blade is within the above range and a small angle is taken, it is preferable in that the steel pipe pile can bite well and the tip blade of the conventional SMD pile can be used as it is.

In the present invention, the second blade is not particularly limited as long as it has an inclination angle different from that of the first blade, and examples thereof include a spiral blade, a partial spiral blade, and a horizontal blade. The second blade has a function of disturbing (stirring) the ground around the steel pipe and enhancing the adhesion to the soil cement in the composite pile. The partially spiral blade includes a so-called inclined blade. These second blades may be installed by bolting a blade welded or partized on the peripheral surface of the steel pipe. The inclination angle α _x of the second blade is appropriately determined as 0 to 52 degrees, preferably 0 to 40 degrees, and a value different from that of the first blade. An inclination angle of 0 means a horizontal blade. In the case of a horizontal blade, the inclination angle is clearly different from that of the spiral first blade, which contributes to disturbance of the ground. In particular, when performing the up-and-down motion process (III process) of the steel pipe pile 10, the disturbance of the ground is further increased and cement milk can be easily injected.

The inclination angle of the first blade and the second blade directly above is preferably 1.5 to 2.5 times, preferably 1.8 to 2.3 times, particularly preferably 2 times, In the case of the second blade, the respective inclination angles between the second blades are preferably different from each other by 1.2 to 1.7 times, preferably 1.3 to 1.6 times. If the ratio of the inclination angle between the blades is too small, the stirring effect is lowered, and if the inclination ratio is too large, the number of blades installed is limited. Incidentally, when the second blade is two or more, the inclination angle of all of the second blade, with a different inclination angle alpha ₀ of the first blade, preferably those each having different inclination angles. When the second blade is two three-stage blades, the inclination angle α ₀ : α ₁ : α ₂ ratio is preferably 1: 1.7 to 2.3: 2.7 to 3.3, particularly preferably. 1: 2: 3 (see FIG. 2). For example, the second blade is two three-stage blades, the inclination angle α ₀ : α ₁ : α ₂ ratio is 1: 2: 3, and the depth dimension by one rotation of the first blade is 1 / When the diameter is 3 (the diameter is the diameter of the steel pipe pile), the inclination angle α ₀ is 9 degrees, the inclination angle α ₁ is 18 degrees, and the inclination angle α ₂ is 27 degrees. Further, the second blade is two three-stage blades, the inclination angle ratio α ₀ : α ₁ : α ₂ is 1: 2: 3, and the depth dimension by one rotation of the first blade is 1 / In the case of two diameters, the inclination angle α ₀ is 14 degrees, the inclination angle α ₁ is 28 degrees, and the inclination angle α ₂ is 42 degrees. In addition, when the depth dimension by one rotation of the first blade is 6 cm and the pile diameter is 89.1 to 138.5 mm, the inclination angle α ₀ of the first blade is 6 to 19 degrees, and the inclination angle α ₁ is 11 to 34. degrees, the inclination angle alpha ₂ is 16 to 45 degrees. When the depth dimension of the first blade by one rotation is 7.5 cm and the pile diameter is 89.1 to 138.5 mm, the inclination angle α ₀ of the first blade is 7 to 23 degrees and the inclination angle α ₁ is 13 40 degrees, the inclination angle alpha ₂ is 20-48 degrees. Further, above the first blade, separate from the second blade, the blade having the same inclination angle alpha ₀ and the inclination angle alpha ₀ of the first blade may be formed.

In the present invention, as a modified example in which the ratio of the inclination angle α ₀ : α ₁ : α ₂ between the first blade and the second blade in the case of two second blades is 1: 2: 3, the inclination angle α ₀ : α ₁ : alpha ₂ ratio of 1: 3: 2, 2: 1: 3, 2: 3: 1, 3: 1: 2,3: 2: 1 are mentioned.

In the steel pipe pile of the present invention, the vertical length between the start point and the end point of the blade (hereinafter also simply referred to as “vertical direction length”) is H on the outer peripheral surface of one end portion in the axial direction of the hollow steel pipe. A spiral first blade of ₀ is attached, and one or more second blades having a vertical length H _x of the blade different from H ₀ are formed on the outer peripheral surface above the first blade. In the present invention, when the second blade is a blade that is difficult to define by an inclination angle, it can be defined by the vertical length of such a blade. The start point and end point of the second blade are on the same line in the axial direction (vertical direction). Accordingly, when the start point and the end point of the second blade are not on the same line in the axial direction (vertical direction), the second blade is determined by an imaginary line whose tip extends along the blade shape.

The vertical length H ₀ of the first blade (spiral blade) is preferably 5 to 45 cm. When the vertical length H _{0 of} the first blade is in the above range and takes a small length, the steel pipe pile bites well, and the tip blade of the steel pipe pile such as a conventional SMD pile can be used as it is. preferable.

In the present invention, the second blade is not particularly limited as long as it has a different vertical length from the first blade, and examples thereof include a spiral blade, a partial spiral blade, and a horizontal blade. The second blade has a function of disturbing (stirring) the ground around the steel pipe and enhancing the adhesion to the soil cement in the composite pile. The vertical length Hx of the second blade is appropriately determined as a value different from that of the first blade in the range of ₀ to 45 cm, preferably 0 to 30 cm. A vertical length of 0 refers to a horizontal blade. In the case of a horizontal blade, the length in the vertical direction is clearly different from that of the spiral first blade, which contributes to ground disturbance.

The vertical length of the first blade and the second blade directly above is preferably 1.5 times to 2.5 times, preferably 1.8 to 2.3 times, and particularly preferably twice as long, In the case of a plurality of second blades, the vertical lengths between the second blades are preferably different from each other by 1.2 times to 1.7 times, preferably 1.3 to 1.6 times. If the ratio of the lengths in the vertical direction between the blades is too small, the stirring effect is reduced, and if the length ratio in the vertical direction is too large, the number of blades installed is limited. When there are two or more second blades, it is preferable that the vertical lengths of all the second blades are different from the vertical length H _{0 of} the first blades, and the vertical lengths are different from each other. When the second blade is two three-stage blades, the vertical length H ₀ : H ₁ : H ₂ ratio is preferably from 1: 1.7 to 2.3: 2.7 to 3.3, particularly Preferably, it is 1: 2: 3. Further, above the first blade, separate from the second blade, the vertical length H ₀ and the blade having the same vertical length H ₀ of the first blade may be formed.

In the present invention, as a modification example in which the vertical length H ₀ : H ₁ : H ₂ ratio of the first blade and the second blade in the case of two second blades is 1: 2: 3, the vertical length H Examples include ₀ : H ₁ : H ₂ ratios of 1: 3: 2, 2: 1: 3, 2: 3: 1, 3: 1: 2 and 3: 2: 1.

In the present invention, the number of installed second blades is 1 or more, preferably 1 to 4, and particularly preferably 1 to 3. One second blade means a two-stage blade including the first blade, two second blades mean a three-stage blade including the first blade, and three second blades are the first blade. Means four-stage blades. The steel pipe pile with the second blade of 0 is only the first blade (conventional SMD pile), the region through which the blade passes cannot be disturbed, and the effect of the present invention cannot be achieved. The number of second blades to be installed is appropriately determined depending on the length of the steel pipe pile and the soil quality. As the number of installed second blades increases, the ground disturbance effect increases, while the load is increased. The distance between the lower blade immediately below the upper blade, placed the number of blades is appropriately determined by such pipe pile length and soil, generally 0~H _y / 2 (H _y is the lower wing that forms the gap Vertical length)), preferably 0 to H _y / 3. If the distance between the upper blade and the lower blade directly below is too large, the number of blades installed is limited. In addition, it is preferable to install all the blades within about 1 m from the tip in relation to the construction depth.

  In the steel pipe pile of the present invention, the blade diameters of the first blade and the second blade vary depending on the length and soil quality of the steel pipe pile, and cannot be determined unconditionally, but at most three times the steel pipe diameter and at the minimum the steel pipe diameter + (4 cm ) Is preferred. That is, in the composite pile, the thickness of the soil cement coating is at least 2 cm. If there is a coating layer of this level of soil cement, corrosion prevention of the steel pipe is sufficient. The blade diameter of the first blade and the blade diameter of the second blade are preferably the same.

Next, the steel pipe pile in the 1st Embodiment of this invention is demonstrated with reference to FIG.1 and FIG.2. The steel pipe pile 10 is attached to the outer peripheral surface 11 at one end in the axial direction of the hollow steel pipe 1 with a spiral first blade 2 at an inclination angle α ₀ with respect to a direction perpendicular to the axial direction of the steel pipe 1. the outer peripheral surface of the upper first blade 2, the second blade 3a having a large inclination angle alpha ₁ than the inclination angle alpha _0, to the outer peripheral surface of the upper second blade 3a, the inclination angle of the larger than the inclination angle alpha ₁ the second blade 3b having alpha ₂ respectively is obtained by forming at a predetermined interval.

In the steel pipe pile 10, the number of the second blades is not limited to two and may be m (m is an integer of 1 or more). In this case, the inclination angle α _n (n is an arbitrary integer of m) of the second blade (n) is larger than the inclination angle α _n-1 of the blade (n-1) directly below, where m is 1 In this case, the inclination angle α ₁ of the upper blade can be defined to be larger than the inclination angle α ₀ of the blade immediately below. That is, when m is 3, the top is greater than the inclination angle alpha ₂ of the inclination angle alpha ₃ vane immediately below the blades of (4-stage) (third stage), the blades of the third stage the inclination angle alpha ₂ is greater than the inclination angle alpha ₁ of the blades (second stage) immediately below, the inclination angle alpha ₀ of the inclination angle alpha ₁ of the blades of the second-stage first blade immediately below (bottom) Is greater. Further, as shown in FIGS. 1 and 2, when m is 2, than the inclination angle alpha ₁ of the topmost inclination angle alpha ₂ is wing immediately below the blades of (third stage) (second stage) a large inclination angle alpha ₁ of the blades of the second stage is greater than the inclination angle alpha ₀ of the first blade immediately below (bottom).

  In the steel pipe pile 10, the inclination angle of the upper blade is preferably 1.2 to 2.5 times the inclination angle of the blade immediately below, and preferably 1.3 to 2.3. Further, the vertical length of the upper blade is preferably 1.2 to 2.5 times the vertical length of the blade directly below, and preferably 1.3 to 2.3. If the blades having different inclination angles and vertical lengths including the first blade are two or more, preferably three or more, the ground around the steel pipe can be sufficiently disturbed. The tip of the steel pipe pile 10 may be either an opening or a closing port. When the tip is an opening, an inner blade or an inner excavation blade may be formed inside the steel pipe. When the tip of the steel pipe pile 10 is an opening, the opening is blocked with soil during the penetration, and the penetration is stabilized.

Further, the steel pipe pile 10 has a vertical length H _n (n is an arbitrary integer of m) between the start point and the end point of the upper blade (n) between the start point and the end point of the immediately lower blade (n−1). It is greater than the vertical length H _n−1 , but when m is 1, it can be defined that the vertical length H ₁ of the upper blade is greater than the vertical length H ₀ of the blade immediately below it. . That is, when m is 3, the vertical length H ₃ of the blade at the top (fourth stage) is greater than the length H ₂ of the blade (3 stage) immediately below, the third stage of a said large than the length H ₁ of the vertical length H ₂ vane immediately below the blades (second stage), the vertical length H ₁ of the blades of the second-stage first blade immediately below ( It is larger than the length H ₀ of the lowermost stage. Further, as shown in FIGS. 1 and 2, when m is two, vertical length H ₂ vane immediately below between the start point 31b and the end 32b of the blade 3b of the top (third stage) ( a the larger than the length H ₁ of the second stage), vertical length H ₁ between the starting point 31a and the end 32a of the second-stage blade 3a and the first starting point 21 of the blade (bottom) immediately below It is larger than the length H ₀ in the vertical direction between the end points 22.

  In addition, in the steel pipe pile 10, the position of the start point 21 of the 1st blade | wing 2, the start point 31a of the 2nd blade | wing 3a, and the position of 31b of the 2nd blade | wing 3b exists in the same point in planar view (it exists in the same perpendicular direction). However, the present invention is not limited to this, and the respective starting points may be at different positions in plan view. Specifically, the starting point 31a of the second blade 3a is 70 to 126 degrees, preferably 70 degrees, from the starting point 21 of the first blade 2, and the starting point 31b of the second blade 3b is from the starting point 31a of the second blade 3a. It may be 70 to 126 degrees, preferably 70 degrees apart. Thereby, the poor stirring part is eliminated and the stirring efficiency is improved.

Next, the ground disturbing action of the blades in the steel pipe pile 10 will be described. The steel pipe pile 10 penetrates into the ground while rotating in the forward direction (reference X direction). The first blade 2 is a spiral blade, and penetrates the ground for a depth H ₀ by one rotation of the steel pipe. Until the second blade (first second blade) 3a enters the ground, the spiral-shaped orbit of the first blade 2 is cut in the ground, and the track portion is hollowed out. Next, the second blade 3a enters the ground. Since the ground through which the second blade 3a passes is the ground through which the first blade 2 has passed, it is not a virgin ground. Therefore, the trajectory of the first blade 2 becomes rate-limiting, the second blade 3a, it only travels H ₀ minutes at proceeding H ₁ minute per revolution if it alone blade. That is, the 2nd blade | wing 3a does not rotate according to a spiral shape, but advances while shifting | deviating to a horizontal direction. At this time, the second blade 3a cuts the passing ground and can disturb the ground. The second blade 3a further exerts a pressing force in the downward and lateral directions, so that a consolidation effect on the lower ground and the surrounding ground appears. Next, the second blade 3b enters the ground. Since the ground through which the second blade 3b passes is the ground through which the first blade 2 and the second blade 3a have passed, the ground is disturbed. Therefore, the trajectory of the first blade 2 becomes rate-limiting, the second blade 3b, it only travels H ₀ minutes where proceeds ₂ minutes H in one revolution if it alone blade. That is, the second blade 3b does not rotate in a spiral shape as will proceed H ₀ minutes while laterally offset. At this time, the second blade 3b cuts the passing ground and can greatly disturb the ground. Since the second blade 3b is further pressed downward and laterally, a compacting effect on the lower ground and the surrounding ground appears.

Next, the steel pipe pile in the 2nd Embodiment of this invention is demonstrated with reference to FIG. In FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals, description thereof is omitted, and different points will be mainly described. 3 differs from the steel pipe pile 10 of FIG. 2 in the inclination angle of the first blade and the second blade and the vertical length of the blade. That is, steel pipe piles 10A is a top small inclination angle alpha ₂ of the blade 23b from the inclination angle alpha ₁ of the blades (second stage) 23a just below its (third stage), the second stage of vanes 23a the angle of inclination alpha ₁ is smaller than the inclination angle alpha ₀ of the first blade (bottom) 2a directly below. Further, a top small vertical length _{H 2} of the blade 23b than the length _{H 1} of the blade (2 stage) 23a immediately below the (3-stage), the vertical of the second-stage vanes 23a direction length H ₁ is smaller than the vertical direction the length H ₀ of the first blade (bottom) 2a directly below. That is, while the steel pipe pile 10 is directed upward, the inclination angles of the plurality of blades are sequentially increased, whereas the steel pipe pile 10A is directed upward, and the inclination angles of the plurality of blades are sequentially reduced. It is going.

Next, the ground disturbing action of the blades in the steel pipe pile 10A will be described. The steel pipe pile 10A penetrates into the ground while rotating forward. First blade 2a is spiral blade and a depth H ₀ minutes penetration into the ground in one rotation of the steel pipe. Until the second blade (first second blade) 23a enters the ground, the spiral-shaped orbit of the first blade 2a is cut in the ground, and the track portion is hollowed out. Next, the second blade 23a enters the ground. Since the ground through which the second blade 23a passes is the ground through which the first blade 2a has passed, it is not a virgin ground. Therefore, the trajectory of the first blade 2a is a rate-limiting, the second blade 23a is the place does not proceed only H ₁ minute 1 rotation If this single blade, travel through a long H ₀ minutes more. That is, the 2nd blade | wing 23a does not rotate according to a spiral shape, but advances while cutting down the ground below. Next, the second blade 23b enters the ground. Since the ground through which the second blade 23b passes is the ground through which the first blade 2a and the second blade 23a have passed, it is a disturbed ground. Therefore, the trajectory of the first blade 2a is a rate-limiting, the second blade 23b is the place does not proceed only H ₂ partial one rotation If this single blade, travel through a long H ₀ minutes more. That is, the second blade 23b does not rotate in a spiral shape as will proceed H ₀ minutes while scraping below the ground. In this way, the second blades 23a and 23b cut the passing ground and can greatly disturb the ground.

Next, the steel pipe pile in the 3rd Embodiment of this invention is demonstrated with reference to FIG. 4, the same components as those in FIG. 2 are denoted by the same reference numerals, description thereof will be omitted, and different points will be mainly described. 4 differs from the steel pipe pile 10 of FIG. 2 in the inclination angle of the first blade and the second blade and the vertical length of the blade. That is, steel pipe piles 10B is a top small inclination angle alpha ₂ of the blade 33b from the inclination angle alpha ₁ of the blades (second stage) 33a immediately below the (3 stage), the first blade (bottom ) It is larger than the inclination angle α _{0 of} 2b. The inclination angle alpha ₁ of the second stage vanes 33a is larger than the inclination angle alpha ₀ of the first blade (bottom) 2b immediately below. Further, the top is a small vertical length _{H 2} of the blade 33b than the length _{H 1} of the wing (2 stage) 33a immediately below the (third stage), the first blade (bottom) 2b it is greater than the vertical length H ₀ in. Vertical length H ₁ of the second stage vanes 33a is greater than the vertical direction the length H ₀ of the first blade (bottom) 2b immediately below. That is, in the steel pipe pile 10B, the inclination angle of the plurality of blades increases from small to large and then decreases toward the top.

Next, the ground disturbing action of the blades in the steel pipe pile 10B will be described. The steel pipe pile 10B penetrates into the ground while rotating forward. First blade 2b is spiral blade and a depth H ₀ minutes penetration into the ground in one rotation of the steel pipe. Until the second blade (first second blade) 33a enters the ground, the spiral orbit of the first blade 2b is cut in the ground, and the track portion is hollowed out. Next, the second blade 33a enters the ground. Since the ground through which the second blade 33a passes is the ground through which the first blade 2b has passed, it is not a virgin ground. For this reason, the trajectory of the first blade 2b becomes the rate-determining, and the second blade 33a advances only for H ₁ minutes in one rotation if it is a single blade, but advances only for H ₀ shorter than that. That is, the 2nd blade | wing 33a does not rotate according to a spiral shape, but progresses while shaving the ground in a horizontal direction. Next, the second blade 33b enters the ground. Since the ground through which the second blade 33b passes is the ground through which the first blade 2b and the second blade 33a have passed, the ground is disturbed. Therefore, the trajectory of the first blade 2b becomes rate-limiting, the second blade 33b is the place to proceed ₂ minutes H in one revolution if it alone blade does not proceed only it shorter H ₀ minutes. In other words, the second blade 33b does not rotate according to the spiral shape, and advances only for H ₀ while cutting the ground in the lateral direction. In this way, the second blades 33a and 33b cut the passing ground, and can greatly disturb the ground.

  The steel pipe pile of the present invention is not limited to the above-described embodiment, and as the steel pipe pile 10, the inclination angle gradually increases as it goes upward, or the reverse of the steel pipe pile 10A. As in the form in which the inclination angle becomes gradually smaller, there is no regularity, and blades with different inclination angles may be formed alternately or randomly. When there are a plurality of second blades, the distance (pitch) between adjacent blades may be the same or different between all the blades.

(Description of composite pile manufacturing method)
The manufacturing method of the composite pile of this invention has the process (I process) which supplies a solidification material to the surroundings of the steel pipe of this steel pipe pile, penetrating the said steel pipe pile in the ground by normal rotation. The method of supplying the solidified material around the steel pipe pile is preferably based on gravity flow from the solidified material storage tank. Examples of the solidifying material include powdery solidifying material or cement milk.

  Then, an example of the manufacturing method of the composite pile of this invention is demonstrated with reference to FIGS. In FIG. 10, the code | symbol 71 is a soft ground and the code | symbol 72 is a hard ground (support ground). Prior to penetrating the steel pipe pile 10, a cylindrical can (solidification material storage tank) 4 including the penetrating portion and vertically penetrated is installed on the ground surface. The cylindrical can 4 can be simply placed on the ground surface. A steel pipe pile 10 is erected in the cylindrical can 4 (FIG. 8), and a design amount of the solidified material 5 is put into the cylindrical can 4. In this example, the solidifying material 5 is cement milk. Next, a rotational torque is applied to the pile head, and the steel pipe pile 10 is penetrated into the ground 7 by normal rotation. The ground disturbing action of the blades in the steel pipe pile 10 is as described above, and with the penetration of the steel pipe pile 10, the second blade disturbs the ground around the steel pipe 11 and within the blade diameter while consolidating the surrounding ground. A void will be formed in the ground. In the ground under disturbance, the cement milk 5 in the cylindrical can 4 flows down by gravity. That is, the cement milk 5 is filled in the ground around the steel pipe 11 with the penetration of the steel pipe pile 10 (step I). Since the cement milk 5 is filled in synchronism with the penetration of the steel pipe pile 10, it is sufficiently mixed with the disturbed earth and sand (FIG. 9).

In order to further accelerate the disturbance of the ground during the process I, an intrusion start point changing process (process II) for correcting the blade trajectory may be performed. Step II is performed as follows. That is, penetration of the steel pipe pile 10 is stopped in the middle of performing the I process. While the steel pipe pile 10 is stopped, the steel pipe pile 10 is pulled upward by a predetermined length, and then re-penetrating while rotating the steel pipe pile 10. The length to be pulled up is preferably an appropriate length not more than the vertical length H _{0 of} the first blade 2. Particularly preferred is 1 / 3H ₀ to 1 / 5H ₀ . The starting point of penetration of the first blade 2 is changed by pulling up the predetermined length of the steel pipe pile 10 that has stopped. That is, in re-penetration, a spiral trajectory different from the initial spiral trajectory is taken, and the disturbance of the ground is promoted. If the lifting length is the same as H ₀ , the re-penetration results in the same spiral trajectory as the first spiral trajectory, and does not promote ground disturbance. Further, when the steel pipe pile 10 is pulled up by a predetermined length, the ground can be further disturbed by the first blade 2 and the second blades 3a and 3b, and the ground and cement milk can be mixed. Step II can be performed one or more times, preferably about 2 to 5 times in the middle of Step I.

  In order to forcibly disturb the ground during the process I, the vertical movement process (III process) of the steel pipe pile 10 may be performed. In the process III, the steel pipe pile 10 is moved up and down with a large stroke while the penetration of the steel pipe pile 10 is stopped and the steel pipe pile 10 is stopped during the process I. The stroke to be pulled up is preferably the length from the tip of the steel pipe pile 10 to the uppermost second blade. By moving the steel pipe pile 10 up and down to stir the ground, the cement milk can easily flow down to the stir ground. The re-penetration of the steel pipe pile 10 may be performed from any point. Step III can be performed one or more times, preferably about 2 to 5 times in the middle of Step I.

  In the manufacturing method of the present invention, the first blade 2 may be embedded in the hard ground layer 72. By providing the piercing portion 9 penetrating into the hard ground layer 72, the tip support force of the steel pipe pile 10 is improved. Although the solidifying material 5 penetrates into the rooting portion 9, the solidifying material 5 does not need to penetrate into the rooting portion 9. Moreover, the piercing process of the steel pipe pile 10 is an arbitrary process and may be omitted. I process is complete | finished by the penetration to the design length of the steel pipe pile 10, and supply of the cement milk 5 being complete | finished. Whether the cement milk 5 is sufficiently supplied can be determined by observing the decrease in the cement milk 5 in the cylindrical can 4 during the penetration of the steel pipe pile 10. When the supply of the cement milk 5 is insufficient, the II step or the III step may be performed in the middle of the I step. The penetration of the steel pipe pile 10 is completed, an unhardened soil cement is formed around the steel pipe 11, and the unhardened soil cement hardens to become a steel pipe soil cement composite pile 20 (FIG. 10). The cylindrical can 4 is merely placed on the ground surface and can be easily removed. According to the manufacturing method of the composite pile 20 of the present invention, the steel pipe 11 can be correctly arranged at the center by a simple method of rotating the steel pipe pile 10 while gravity-flowing the solidified material from the ground surface around the steel pipe 11. .

(Description of composite pile)
The composite pile of this invention consists of a steel pipe pile and the soil cement formed around the outer peripheral surface of the steel pipe of this steel pipe pile. Soil cement is a hardened mixture of ground soil and solidified material around steel pipes. Moreover, as shown in FIG. 10, the 1st blade | wing 2 and 2nd blade | wing 3a, 3b of the steel pipe pile 10 are embedded in the soil cement 6, and the adhesiveness of the steel pipe pile 10 and the soil cement 6 is improved. . Further, the composite pile may have a root portion 9 in the hard ground layer 72 as shown in FIG. 10, or a tip that does not reach the hard ground layer 72 and does not have the root portion 9. . The composite pile 20 having the embedded portion 9 in the hard ground layer 72 functions not only as a friction pile but also as a support pile.

  The pile diameter of the composite pile 20 is substantially the same as the blade diameter of the first blade and the second blade, and specifically, the maximum is three times the steel pipe diameter, and the minimum is preferably the steel pipe diameter + (4 cm). If the thickness of the coating of the soil cement 6 is 2 cm, the steel pipe is sufficiently prevented from corrosion and has a supporting function, so that the pile diameter of the composite pile 20 is sufficient. In addition, the composite pile 20 has a surrounding ground that is consolidated, and has a high supporting force as a friction pile.

  The steel pipe pile according to the present invention can be manufactured by simply welding the second blade to the conventional SMD pile, although it has an unprecedented structure. The composite pile only needs to supply the solidified material around the steel pipe under gravity flow while penetrating the steel pipe pile, and the solidified material supply means may be a half-cut drum. For this reason, the composite pile in which the steel pipe is correctly arranged at the center can be manufactured at a low cost by an extremely simple method. Moreover, the alkaline cement is coat | covered around the steel pipe, and the anticorrosion effect of a steel pipe is high. Moreover, the composite pile which functions as a support pile can provide the stable support force over a long period of time.

DESCRIPTION OF SYMBOLS 1 Steel pipe 2, 2a, 2b 1st blade | wing 3a, 3b, 23a, 23b, 33a, 33b 2nd blade | wing 4 Cylindrical can (solidification material storage tank)
5 Solidifying material (cemented milk)
6 Soil cement 7 Ground 9 Rooting part 10, 10A, 10B Steel pipe pile 20 Composite pile

Claims (10)

A spiral first blade is attached to the outer peripheral surface of one end portion in the axial direction of the hollow steel pipe at a tilt angle α ₀ with respect to the direction perpendicular to the axial direction of the steel pipe, and the outer periphery above the first blade the surface, which the second blade for stirring or disturb the ground having an inclination angle αx different from the inclination angle alpha ₀ has been formed one or more, the inclination angle of the second blade directly above the first blade, the inclination angle steel pipe piles, characterized in that than α ₀ is large. On the outer peripheral surface of one end portion in the axial direction of the hollow steel pipe, a spiral first blade having a vertical length H ₀ between the start point and the end point of the blade is attached, and on the outer peripheral surface above the first blade, One or more second blades that stir or disturb the ground having a vertical length Hx between the start point and the end point of the blades different from H ₀ are formed , and the blades of the second blades directly above the first blades vertical length between start and end points, steel pipe piles, characterized in that it is greater than H _0. 2. The steel pipe pile according to claim 1, wherein when there are two or more second blades, the inclination angles of all the second blades are different from the inclination angle α ₀ and are different from each other. When the second wing is more than one, the vertical length between the start and end points of all the second blade, with different and H _0, according to claim 2, characterized in that each of different lengths Steel pipe pile.   The steel pipe pile according to any one of claims 1 to 4, wherein the second blade is a spiral blade, a partial spiral blade, or a horizontal blade.   The steel pipe pile according to claim 1 or 2, wherein the first blade is a spiral blade having one or two turns.   A composite pile comprising the steel pipe pile according to any one of claims 1 to 6 and a soil cement formed around an outer peripheral surface of the steel pipe of the steel pipe pile.   Manufacturing the composite pile characterized by having the process of supplying a solidification material around the steel pipe of this steel pipe pile, penetrating the steel pipe pile of any one of Claims 1-6 in the ground by normal rotation. Method.   The method for producing a composite pile according to claim 8, wherein the method of supplying the solidified material around the steel pipe pile is based on gravity flow from the solidified material storage tank.   The method for producing a composite pile according to claim 8 or 9, wherein the solidified material is a powdered solidified material or cement milk.

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