JP2005098108A5 - - Google Patents

Description

Method of burying ready-made piles, foundation pile structure and ready-made piles

This invention Rutotomoni improves the reliability of the supporting force in Kuiana拡底unit, to increase the pull-out resistance force, and relates to embedded method and the foundation pile structures and prefabricated pile of ready-made pile with enhanced拡底portion.

  Conventionally, when embedding a concrete ready-made pile in a pile hole widening bottom portion, in the straight pile 16 with a constant outer diameter, the bottom surface 17 (outer diameter D) is supported on the supporting ground (the ground bottom surface) 11 (FIG. 15 (a )). Further, even a so-called ST pile 24, which is a ready-made pile and has a large diameter at the lower end, was supported on the support ground 11 by the bottom surface 25 (outer diameter D) (FIG. 15B).

Further, basic structure of the so-called Fushikui provided with ribs on the outer periphery of the pile which has been conventionally carried out, section prefabricated pile there only straight Kuiana relates live load and drawing anti force, the shape and the拡底portion Consideration of the shear stress to the node etc. was inadequate in the dimension and the embedding construction which especially provided the bottom expanded part.

In general, by injecting cement milk in the pile hole, when the method of forming a soil cement layer and cement milk and drilling mud were mixed stirred at the upper portion of Kuiana, drilling mud was left . This is because the packing material in the upper layer of the pile hole overflows on the ground as the ready-made pile descends into the pile hole and is discarded, and it is considered that the quality of the pile structure is not affected.
Japanese Patent No. 3020187 Japanese Patent No. 2651893

In conventional ready-made piles, it is considered that the expression of the support force is mainly limited to the bottom surfaces 17 and 25 of the ready-made piles, and the magnitude of the support force depends on the width of the bottom area of the ready-made piles. Also, the magnitude of the pulling resistance had largely for by the surface friction of the pile, depending on the sizes of the relevant surface area. Therefore, the outer diameter DD ₁ of the expanded bottom portion 28 of the conventional pile hole 26 is limited to about 1.2 to 1.5 of the outer diameter DD ₀ of the shaft portion 27. In addition, there is a special amount of adhesion between the side surfaces 16a and 24a of the ready-made pile at the time of burial and the end surfaces 17 and 25 of the lower end of the pile and the cement milk solidified in the pile hole 26 or soil cement mixed with excavated soil. It had not been consideration of (Figure 15).

Further, Fushikui is a pile having a function to be held in the ground by the frictional force at the sides, usually, the length of the pile (depth Kuiana) was Tsu der about 10 to 30 m. Therefore, it is used in a completely different standard field from the straight piles 16 and the like, and the bottomed portion for solidifying has not been formed. Therefore , the support force and the pull-out resistance force at the lower end are not particularly considered, and it is a substance that does not have a foundation structure that makes full use of the strength of the pile node.

That is, in Kuiana a straight embedding the Fushikui, Kuiana径at substantially the same diameter as the knuckles outer diameter, a slight gap between the pile unit and the Kuiana inner wall further with regard construction of the root hardened portion , lower end surface of the pile and, considering shearing force by the upper and lower stress propagated from the lower end portion each node portions, drilling and buried installation of piles in the shape and dimensions of the well utilizing the Kuiana piles performance line It wasn't.

In addition, when the ready-made pile is lowered through the excavated mud layer remaining in the upper part of the pile hole, it is buried in the pile hole with the mud film formed on the outer surface of the ready-made pile. In addition, there was a problem that initial settlement occurred and cement milk or soil cement and the ready-made pile could not be sufficiently integrated in the pile hole.

    Therefore, it is necessary to improve the stability of the quality at the time of initial subsidence when the bearing capacity of the pile is developed, and there is no construction method that takes into account the geology with poor bearing capacity including silt, etc. However, there was a problem that the strength of each ready-made pile was not utilized effectively corresponding to the stratum.

    In addition, in order to fully demonstrate the performance of each pile in the foundation pile, several connected piles are usually adopted, but in the case of heterogeneous connected piles using joint piles that are representative of conventional protruding piles, vertical support is used. The lower pile using the friction force due to the projections (nodes) mainly as the force and the cylindrical pile having the predetermined bending stress as the horizontal support force are made as the upper pile, and the shaft diameter of both piles is Usually, it is comprised as the same dimension (for example, patent 2651893 etc.). In other words, the heterogeneous pile connection with the lower pile with protrusions is composed of an upper pile (cylindrical pile) with horizontal bearing capacity and a lower pile (node pile) with frictional force, and the shaft diameters of both piles are set to the same size. It was the method of connecting both in a part. In addition, various structures have been proposed in which the horizontal force of the upper pile is strengthened as the dimensions of the shaft diameters of both piles are different, and the changed part of the pile diameter dimension is provided in the pile body or the pile connection part. Is located in the shaft part of the pile hole and the changed part cannot be sufficiently reinforced with pile circumference soil cement, etc., and it is difficult to respond from the technical and economic aspects to the strength and stress concentration of the changed part. there were. Therefore, in the conventional connection technique, for example, when the supporting force of the lower pile is large, it is not possible to adopt the pile shape / outer diameter dimension in which the horizontal supporting force of the upper pile is the optimum value. As a whole, the optimal connection configuration could not be designed. In other words, it was difficult to achieve the optimum bearing capacity for the entire foundation pile.

However the invention includes within Kuiana拡底part, by employing a buried methods and new basal Kui構Concrete prefabricated pile buried prefabricated piles having a projection on the outer periphery, it has solved the problem.

That is, the present invention excavates a pile hole having a widened portion, injects cement milk into the widened portion and agitates it to form a soil cement with the excavated soil and cement milk, and at least on the outer periphery of the lower end portion. Lowering the ready-made pile having a protrusion and fixing it so that at least one of the protrusions fits into the expanded bottom portion, and forming a predetermined gap between the lower surface of the protrusion and the ground bottom surface of the expanded bottom portion of the pile hole A method for burying a ready-made pile characterized by: excavating a pile hole having an expanded bottom, injecting cement milk into the expanded bottom and stirring to form a soil cement with excavated soil and cement milk; to, lowers the prefabricated pile having a projection at least on the lower end outer periphery, at least one of said protrusions is allowed to settle so as to fit into拡底portion, and a lower surface of the protrusion, ground bottom surface of Kuiana拡底portion And between the upper surface of the projection, between the top surface of the Kuiana 拡底 portion is buried method prefabricated pile which is characterized in that to form a predetermined gap.

Further another aspect of the present invention, the cement milk, solidified strength of soil cement is, it is an intensity and mechanically strength such that homogeneous or more support ground.

Further, in the bottom expanded portion of the pile hole lower portion, a soil cement mixed with excavated soil and cement milk is filled, and into the soil cement, a ready-made pile having a protrusion on the outer periphery of the lower end is inserted and installed, into the expanded bottom portion, At least one protrusion of the ready-made pile is inserted, and a predetermined gap is provided between the lower surface of the protrusion and the ground bottom of the expanded bottom portion, and the soil cement is filled in the gap. It is a characteristic foundation pile structure.

  Next, the lower end is a prefabricated pile embedded in the expanded bottom portion of the pile hole, and a protrusion is provided at a position having a predetermined gap from the bottom surface of the expanded portion in the shaft portion of the pile entering the expanded bottom portion. The shaft portion that enters the pile hole other than the widened portion is straight, and one or more projections of the shaft portion in the widened portion are provided.

  Another embedding method is to excavate a pile hole having an expanded portion, and then inject cement milk into the expanded portion so that the solidification strength is mechanically equal to or higher than that of the supporting ground. A soil cement layer is formed almost up to the pile mouth, and a ready-made hollow pile having projections at least at the outer periphery of the lower end portion is lowered in the pile hole while rotating if necessary, and the lower end portion of the ready-made pile is placed in the pile hole. A method for burying a ready-made pile to be fixed in an expanded bottom portion, wherein a predetermined gap is formed between the bottom end surface of the ready-made pile and a ground bottom surface of the bottom portion of the pile hole, and the uppermost position located in the expanded bottom portion of the ready-made pile. A pre-built pile embedding method characterized in that a predetermined gap is formed in the vertical direction between the projection at the position and the uppermost position of the pile hole widened portion, and a soil cement layer is formed in both the gaps.

  Further, another embedding method is to excavate a pile hole having a bottom portion in a layer having poor geology, and then, in the bottom portion, a predetermined cement milk whose solidification strength is mechanically equal to or higher than that of the supporting ground. And then replacing the excavated soil in the expanded bottom with the cement milk, and subsequently forming a soil cement layer up to the substantially pile hole opening in the pile hole shaft, and having a protrusion at least at the outer periphery of the lower end in the pile hole , While rotating, if necessary, and a method of burying a ready-made pile that fixes the lower end portion of the ready-made pile at a predetermined position in the bottom of the pile hole, the lowest end surface of the ready-made pile and the pile A predetermined gap is formed between the bottom of the hole and the bottom of the ground, and a predetermined gap is formed in the vertical direction between the uppermost protrusion located on the bottom of the ready-made pile and the uppermost position of the pile hole. And forming a cement milk layer in the gaps Preparative a burying method of prefabricated pile was characterized by.

In the burying method, a pile hole having an expanded bottom portion having a predetermined outer diameter is excavated, and then cement milk is injected into the pile hole, and the pile hole shaft portion forms a soil cement layer almost to the pile hole opening, and the pile hole A pre-made pile having a protrusion at least at the outer periphery of the lower end, and a predetermined gap is formed between the bottom surface of the ground and the lowest end surface of the pre-made pile. A predetermined gap is formed in the vertical direction between the uppermost protrusion located at the bottom of the pile and the uppermost position of the pile hole bottom, and a soil cement layer or a cement milk layer is formed in both the gaps, This is a burying method in which protrusions on the outer periphery of the lower end of the ready-made pile are embedded in the expanded bottom portion of the pile hole, and the expanded outer diameter D ₁₁ is set to a value not less than A and not more than B below. However, A and B are the following values.

A = {shaft outer diameter of ready-made pile} + {(thickness of soil cement layer between bottom end surface of ready-made pile and ground bottom of widened portion) ÷ √3} × 2
B = {outside diameter of the protrusion of the ready-made pile} + {[(height from the lowermost end surface of the ready-made pile to the uppermost protrusion in the widened portion) + (the lowermost end surface of the ready-made pile and the bottom of the ground of the widened portion) The thickness of the soil cement between)) ÷ √3} × 2
In the embedding method, the pile hole is constructed by excavating a bottom portion having an outer diameter of about 1.2 to 2.5 times the outer diameter of the shaft portion of the pile hole.

In the above, “the outer diameter D ₁₁ of the expanded bottom portion is not less than the value of A and not more than B” or “the outer diameter of 1.2 to 2.5 times the outer diameter of the shaft portion of the pile hole” The reason why the pile hole is formed by excavating the widened portion is to exhibit an efficient supporting force with respect to the pile itself including the protruding portion with a smaller excavation diameter of the bottom expanded portion. In addition, in the above, the interval between the protrusions is at least larger than √3 times the “height from the shaft outer diameter of the ready-made pile to the tip of the protrusion”. This is to propagate the support pressure.

Keru you before Symbol √3 represents the "square root 3 (about 1.732 ...)".

A built-up pile with a protrusion at the lower end is buried in the pile hole excavated at the bottom, and a pile structure with a good integration quality of the ready-made pile and soil cement is constructed. There were propagated on the support ground, it is possible to form a supporting surface on the supporting ground or拡底upper surface at the conical bottom or top surface of a predetermined angle, in order can be supported throughout拡底unit, one pile to be borne The vertical load and the pulling force can be increased significantly (twice or more) than before.

Further, by sinking a prefabricated pile to form a soil cement to pile Anaguchi, so as not to form a fixed layer of Dodoro on the surface of the knuckles or the like of the ready-made pile, the better the close contact between the prefabricated pile and soil cement, soil it is possible to prevent the initial subsidence at the time of the cement solidification.

In addition, if the buried ground contains silt, etc., and the quality of the supporting ground is not good, the excavated soil and cement milk are replaced. Therefore, the quality of the soil cement is not affected by the geology of the supporting ground. Stable strength and quality can be obtained.

In addition, a protrusion is provided and the upper shaft diameter is made larger than the lower shaft diameter, and an inclined step portion that gradually increases in diameter toward the upper side is provided to constitute a ready-made pile. the also is positioned within拡底of Kuiana, since the embedded prefabricated pile into Kuiana, in addition to supporting lifting pressure from the projection, by also adding supporting lifting pressure from the inclined step portion, the vertical load have even higher Can withstand.

In addition, by changing the thickness and compressive strength etc. of the ready-made pile with protrusions, considering the balance between the lower pile and upper pile with protrusions, the lower pile and upper pile have almost the same axial force strength. by setting, to a substantially constant axial force strength of the entire prefabricated pile, it is possible to prevent destruction of the pile material when an excessive load is applied efficiently.

(1) The excavation rod is rotated forward to excavate the shaft portion (hole diameter D ₀₀ ) 2 of the pile hole 1 equivalent to a normal pile hole.

(2) by reversing the drill rod (using or other drilling head for expanding drilling), excavating拡底portion 3 to Kuiana 1 (FIG. 1 (a)), the hole diameter D _11. Cement milk (solidifying strength of about 100 to 300 kg / cm ² corresponding to the strength of the supporting ground) is poured into the expanded bottom portion 3 and stirred and mixed with excavated soil to form a soil cement. Next, cement milk as a pile circumference fixing liquid is poured into the pile hole shaft and stirred with the excavated soil to form a soil cement up to the pile hole opening.

(3) Next, a concrete ready-made pile (shaft diameter D ₀ ) 4 having annular ribs ( protrusions, outer diameter D ₁ ) 5, 6, 7 formed at the lower end in the pile hole 1 is lowered (FIG. 1). (B)). The annular ribs are 5, 6, 7 in order from the bottom.

(4) The bottom end of the pile hole 1 is located at the predetermined height DH ₁ (thickness corresponding to the required strength of the soil cement ) from the ground bottom surface 11 of the bottom expanded portion 3 in the bottom expanded portion 3 . The pile structure 10 is constructed by burying the ready-made pile 4. In its This is embedded as the annular rib 5 and 6 are arranged in拡底portion 3 of Kuiana 1.

(5) Here, when a vertical load acts on the ready-made pile 4, not only the lower end surface 8a of the shaft portion 8 of the ready-made pile 4, but also the lower surfaces 5a and 6a of the annular ribs 5 and 6 on the side surface of the ready-made pile 4 in the periphery, the shearing force is propagated, angle occurs supported lifting pressure portion corresponding to the conical bottom of each corner theta ₁ (about 30 °), the supporting ground surface (ground bottom) 11, D _8a, D _5a, acts on the order of D _6a, an annular rib 5, 6 at拡底portion within 13, due to the high integrity of the soil cement, the vertical load is expressed throughout拡底unit.

Therefore, compared with the conventional straight pile (approximately D ₀ corresponds) can significantly increase the one bearing capacity of piles structure 10.
(6) Next, when a drawing stress is applied to the ready-made pile 4, shear force propagates at the peripheral edges of the upper side 5 b and 6 b of the annular ribs 5 and 6 , and each has an angle θ ₂ (about 30 °). The gap DH ₂ (soil cement) acts between the uppermost annular rib 6 in the expanded bottom portion 3 and the horizontal plane X of the uppermost end of the expanded bottom portion 3 (the lowest end of the pile hole shaft portion 2). the a required intensity component thickness.) is provided (i.e. DH ₂ between are not formed annular rib) due to high annular rib integral of soil cement portion of the inside拡底part 3, pulling resistance拡底part can be expressed in all body. Accordingly, the pulling force of a single pile can be greatly increased as compared with a straight pile, as in the case of the action of a vertical load .
Here, the supporting force of the projections and, if it is desired to further increase the pullout force is to increase the number of projections of prefabricated pile in拡底portion or ground surface of the lower surface and拡底portion of the outer diameter or the protrusion of the protrusion and (in protrusions are not destroyed limit) by increasing the gap to the upper surface and拡底upper surface of the projections is possible.

Further, in this embodiment, to sufficiently act each other bear range of shear forces one of the projections do not overlap borne range of shear next to the projection, propagation angle of the shear force θ (θ _1, θ ₂₎ Considering the height of each protrusion, there is a sufficient margin between the annular ribs.

Therefore, the number of stages of the projections when increasing (the number of vertical direction), in order to sufficiently exhibit the supporting force of the protrusions, propagation angle theta shear force of each projection as described above (theta _1, theta ₂₎ It is necessary to set an interval in consideration of (FIGS. 1B and 1C).

As described above, if the diameter of the bottom expanded portion 3 of the pile hole 1 is increased to increase the area of the bottom surface as much as possible, the supporting force and the pulling force increase. However, the strength of the ready-made pile, the embedding interval of the ready-made pile, and The optimum excavation diameter of the bottom-expanded part considering excavation efficiency etc. is about 1.2 to 2.5 times the outer diameter of the shaft diameter of the pile hole, and constitutes a pile hole. It is desirable to use ready-made piles with parts.

  In addition, the burying method is effective even in geology where the tip ground strength is less than N value 50, but when the geology is not particularly good, when there is a lot of silt or the like and the strength is affected, the excavated soil in the expanded bottom portion is used. It is possible to replace cement milk to be injected, to reduce mixing of silt and the like as much as possible, to improve the quality of cement milk at least at the bottom expanded portion 3, and to stabilize and improve the strength after solidification.

  That is, based on the above-mentioned invention, when placing and embedding / fixing the protrusions of a prefabricated pile (so-called knots etc.) in the bottomed solidified part of the pile hole, The downward shearing force acting on the protrusion by constructing the foundation pile taking into account the shape and dimensions, the composition of the filling in the bottom of the pile hole, and the embedded position of the ready-made pile in the bottom of the pile hole. It is possible to realize a high vertical bearing pile with a tip bearing force using the same, and also a high pulling force pile using an upward shearing force due to the projection.

  In addition, in the ready-made pile having a high vertical supporting force with a projection and a high pulling force according to the above-mentioned invention, in order to balance with other pile characteristics and constitute a higher performance foundation pile, In order to adapt to the high vertical support force and high pull-out force, etc., by introducing a new technology to form the foundation pile connecting the desired upper pile to the lower pile having the protrusion that demonstrated the tip support force by the protrusion in It is possible to easily realize a well-balanced foundation pile in which desired performance by an upper pile having a predetermined shape dimension, that is, a horizontal support force is adapted.

  Moreover, although the said invention was set as the lower pile which strengthened both the high vertical support force and the high pull-out force, the lower pile which strengthened only one of the high vertical support force or the high pull-out force by the performance of the foundation pile to obtain | require Moreover, an upper pile can be connected and it can also be set as a foundation pile (ready-made pile). Also in this case, an upper pile is connected by the same structure to the lower pile embed | buried in a pile hole (bottom expansion part) by the structure which can strengthen only one of a high vertical support force or a high pull-out force. In this case as well, it goes without saying that a more balanced high-performance foundation pile not obtained in the past can be obtained.

  Embodiments of the present invention will be described with reference to the drawings.

The concrete ready-made pile 4 used in this embodiment forms an annular rib over its entire length. The annular ribs form annular ribs 5 and 6 embedded in the expanded bottom portion 3 of the pile hole 1 and annular ribs 12 and 12 embedded in the shaft portion 2 of the pile hole 1. Moreover, the prefabricated pile 4 is formed with an outer diameter D ₀ = 60cm, outer diameter D ₁ = 75 cm of each annular rib, the annular rib pitch P = 100 cm of the shaft portion 8 (FIG. 2).

Next, a pile hole 1 having a diameter D ₀₀ (80 cm) of the shaft portion 2 and a diameter D ₁₁ (150 cm) of the expanded bottom portion 3 is excavated (FIG. 3A). Here, cement milk having a predetermined solidification strength (300 kg / cm ² ) is poured into the expanded bottom portion 3 of the pile hole 1 and filled with soil cement that is stirred and mixed with excavated soil. The shaft 2 of the pile hole 1 is injected with cement milk of solidification strength (200 kg / cm ² ), and the soil cement (about 30 kg / cm ² ) generated by stirring and mixing with the excavated soil is almost piled. Fills up to the hole.

Subsequently, the ready-made pile 4 is lowered into the pile hole 1, and the lower end portion 9 of the ready-made pile 4 is held in the bottom expanded portion 3 of the pile hole 1. Here, the bottom face (lowermost end face) 8a of the ready-made pile 4 has a height DH ₁ (60 cm) higher than the ground bottom face 11 of the bottom expanded part 3. The thickness of the soil cement layer between the bottom face 8a of the ready-made pile 4 and the ground bottom face 11 The gap DH ₂ (60 cm) is provided between the uppermost annular rib 6 located in the widened portion 3 and the uppermost horizontal plane X in the widened portion 3.

    The pile structure 10 in which the ready-made pile 4 is embedded in the pile hole 1 is constructed by solidifying the soil cement (FIG. 3A).

    In the above, the ready-made pile 4 can also be lowered into the pile hole 1 while rotating. In this way, soil mud can be prevented from being fixed to the surface of the ready-made pile 4.

    In addition, although the lower layer of the buried ground of this example is sandy soil, if the buried ground contains silt or the like and the geology is not good, cement milk is injected into the bottom end of the expanded bottom part, and the silt is not good in strength. Etc. are pushed up and replaced with the upper layer portion of the pile hole to form a cement milk layer having a required strength and quality with as little unwanted silt as possible in the expanded bottom portion.

Next, a vertical load W ₁ is applied to the pile structure 10 and finally (W ₁ = about 1000 kg / cm ² ), the pile structure 10 is broken by generating a crack 13a (FIG. 3 (b)).

The crack 13a is generated from the periphery of the lower surface 6a of the annular rib 6 positioned above in the bottom expanded portion 3 of the pile hole 1, and is downwardly conical 14pr of the bottom surface 14a at an angle θ ₁ (about 30 °). Formed.

    That is, it can be confirmed that the supporting pressure of the ready-made pile 4 is generated not only in the bottom surface 8a but also in the conical shape from the peripheral edges of the surfaces 5a and 6a directed downward of the annular ribs 5 and 6 in the bottom expanded portion 3 (FIG. 1). (C)).

Further, in the pile structure 10 of the same a pile length 14m, was added argument 抜力 _{W 2 (W 2 = 10t /} m 2 or so), finally pile structure 10 not generated is pulling was healthy.

Further, when a pulling force is applied, the pile structure 10 is broken by generating a crack 13b. The crack 13b is generated from the periphery of the upper surface 5b of the annular rib 5 positioned below in the bottom expanded portion 3 of the pile hole 1, and is formed into a conical shape 14pu on the bottom surface 14b upward at an angle θ ₂ (about 30 °) formed with the vertical. It is formed (FIG. 3C).

    That is, it can be confirmed that the pull-out stress of the ready-made pile 4 is generated in a conical shape from the peripheral edges of the surfaces 5b, 6b facing the upper sides of the annular ribs 5, 6 in the widened portion 3 (FIG. 1 (d), FIG. 3 ( c)).

Further, pile structure 10 for a good integrity of the soil cement and the ready-made pile 4, when the vertical load is bought or, as the ground bottom surface 11 of the D _A is also below the ground, stress is propagated ( FIG. 1 (c)).

Further, in the same manner as described above, even when took drawing stress in the pile structure 10, from the horizontal plane X of the top of拡底portion 3 above the ground, as D _B, stress is propagated, anchors manner It plays a role (FIG. 1 (d)).

[Experimental example]
A straight pile 16 having the same shaft diameter D _{0 and} not forming the annular ribs 5, 6,... Is buried in the same degree of cement milk in the pile hole 1 to constitute a foundation pile structure 18 (FIG. 4). ).

When a similar test is performed, a conical crack 13c is generated from the bottom surface 17 of the straight pile 16 of the pile structure 18 and is broken at a vertical load W ₃ (= about 500 kg / cm ² ).

Therefore, W ₁ is about twice W ₃ , and with the addition of the improved quality of the integration of the annular rib and soil cement, which was previously thought not to act on vertical loads, the support pressure was significantly increased. It was confirmed that it was obtained.

Similarly, when the pull-out test is performed, in the case of the foundation pile structure 18 of FIG. 4, a pull-out force of about 5 t / m ² is recognized in a normal calculation value, but as described above, in the pile structure 10 of the present invention. A pulling force W _{2 of} about 10 t / m ^2, more than twice this, was confirmed, and a significant increase was obtained.

That is, in the above experiment, the prefabricated piles 4 are embedded so that the annular ribs 5 and 6 of the prefabricated piles are embedded in the pile hole widening portion 3 of a predetermined diameter filled with the soil cement, and the vertical load and the pulling force are reliably transmitted. A gap DH ₁ is provided between the bottom surface 8 a of the base plate 11 and the ground bottom surface 11 of the widened portion 3, and a gap DH ₂ is provided between the uppermost annular rib 6 positioned in the widened portion 3 and the horizontal surface X of the uppermost portion of the widened portion 3. In addition, it was confirmed that the integrity of the ready-made pile 4 and the soil cement was good, and the result was obtained under other conditions (such as the strength of cement milk).

  Next, another embodiment will be described with reference to FIGS.

In the first embodiment, the annular ribs 5, 6,... Are provided over the entire length of the ready-made pile 4, but at least one annular rib is formed in a portion located in the bottom expanded portion 3 of the pile hole 1. This is an example .

  In the first embodiment, the annular ribs 5, 6,... Are provided, but intermittent protrusions (plane cross-shaped) 21, 22, 23 can be alternately provided up and down (FIG. 5A). The protrusion 21 is from the protrusion pieces 21a and 21a (FIG. 5D), the protrusion 22 is from the protrusion pieces 22a and 22a (FIG. 5C), and the protrusion 23 is from the protrusion pieces 23a and 23a (FIG. 5A). ), Respectively.

Further, in Example 1, but the annular rib 5, 6 and 7 were the same diameter, D ₂ so that the larger diameter in this order from the bottom, D _3, D ₄ and different outer diameters (D ₂ <D ₃ <D ₄ ) (FIGS. 6A and 6B), or conversely, an outer diameter (D ₂ > D ₃ > D ₄ ) that is small (not shown). ).

Another embodiment of the present invention will be described with reference to FIGS. In the foundation pile structure 10 of the first embodiment, the inside of the bottom expanded portion 3 of the pile hole 1 is strengthened against a significant vertical load and pulling force. In this embodiment, the pile hole shaft portion is further strengthened to obtain a foundation pile. The entire structure is a ready-made pile that can realize a well-balanced reinforcement at the shaft and widened part, and it also increases construction efficiency.

  In the first and second embodiments, the vertical support force (vertical load resistance) and the pull-out force are strengthened more than twice as the whole foundation pile, but the ready-made pile in the expanded bottom portion 3 forms protrusions on the shaft portion as a whole. A predetermined strength is ensured. In this case, since the shaft diameter of the ready-made pile in the expanded bottom portion 3 is small for its strength, the shaft diameter of the ready-made pile in the expanded bottom portion 3 remains the same as the upper portion of the ready-made pile. If applied to (the part of the prefabricated pile placed on the pile hole shaft part above the expanded bottom part 3), the strength of the pile material generally tends to be insufficient at the upper part of the prefabricated pile, and the construction range is limited. It also becomes.

  Therefore, from the viewpoint of corresponding to the difference in performance required in the depth direction, the upper pile and the lower pile are connected to form a foundation pile, and the upper pile and the lower pile are configured according to the required performance. It becomes effective. That is, in a construction site where a large bending moment or compressive force is required at the pile hole shaft portion, an upper pile that satisfies a predetermined specification such as strength required at the depth is used. And this upper pile is connected to the lower pile (having a predetermined supporting force and a pulling force) embedded in the expanded bottom portion of the pile hole to constitute a ready-made pile, and in the pile hole satisfying the predetermined performance ( If it is embedded in the bottom expanded part and the shaft part), the construction range is not limited, and it becomes easy to meet the performance specifications required for the entire foundation pile. Thus, if an upper pile and a lower pile are connected and a foundation pile is comprised, it can be set as the foundation pile of a structure desirable also from versatility and a cost surface. In addition, as in the case of connecting the upper pile and the lower pile, even if one ready-made pile is used, depending on the performance required for the upper and lower parts of one ready-made pile, the shaft diameter and protrusion It is also effective to configure the parts with different specifications.

That is, in the bottom expanded root solidified portion according to the present invention, a new technique for forming a foundation pile by connecting a desired upper pile to a lower pile having a protrusion for exerting the tip support force is used. In the pile, by providing a part that adjusts the shape and size of the lower pile to the shaft portion of the upper pile or the shape and size of the outer pile, the shape and size of the connecting portion between the lower pile and the upper pile can be matched or connected easily The size and shape can be reduced. Therefore, the selection range of the shape dimension of the upper pile is expanded, the selection range of the horizontal support force is also expanded, the stress matching between the upper pile and the lower pile is facilitated, and the overall performance as the whole foundation pile can be improved.

  In addition, it is needless to say that the desired upper pile can be similarly adjusted in a well-balanced manner with respect to a bearing having a high pulling force that exerts an upward shearing force due to the protrusion. Furthermore, in the connection between the lower pile and the upper pile, it is desirable that the connection portions of the lower pile and the upper pile are aligned with the adjustment portion of the lower resistance so that they have a cylindrical shape with the same outer diameter. This makes it easy to balance the stress between the upper and lower piles, and is reliable and stable in the connection work.This foundation pile has high performance and requires unprecedented construction management. This is advantageous as well as economical.

The ready-made pile 4 of this embodiment has one or a plurality of upper piles 30 used for a portion located in the shaft portion 2 of the pile hole 1 and a lower pile 32 used for a portion located in the expanded bottom portion 3 of the pile hole 1. It is a hollow concrete pile composed of The upper pile 30 is formed with an outer shape D ₉ (= 700 mm), a wall thickness of 110 mm, and a concrete compressive strength of 850 kg / cm ² (FIG. 8A).

The lower pile 32 has a shaft portion 33 outer diameter D ₀ (= 600 mm) and a shaft portion thickness of 90 mm, and two annular ribs (outer diameter D ₁ = 750 mm) 5 and 6 are formed at the lower end portion and the intermediate portion. The upper end portion is bulged to form a connecting portion (outer diameter D ₉ = 700 mm) 34 with the upper pile 30, and the connecting portion has an inner thickness of 165 mm and a concrete compressive strength of 1000 kg / cm ² . Here, the pile used as the upper pile usually has a large amount of prestress, so the thickness of the upper and lower piles, concrete compressive strength, etc. are varied to make the axial force strength almost the same strength. A step portion 35 whose outer diameter gradually changes is formed at the boundary between the bulging connecting portion 34 and the shaft portion 33 (FIG. 8A). The interval between the annular ribs 5 and 6 of the lower pile 32 and the step portion 35 is such that the annular rib 5 is located at a position 500 mm from the bottom surface 8a of the lower pile 32, the annular rib 6 is located at a position 1500mm, and the step portion 35 is located at a position 2000mm. Form each one.

In this embodiment, the proof strength of each pile material in the foundation pile is configured in a well-balanced manner and a structure that realizes high strength is provided. That is, in the root consolidation part, the lower pile 32 is embedded in the root consolidation part up to the step part 35 including the shaft part 33.

Here, for example, when the stepped portion 35 is taken out from the rooting portion, and the shaft portion 33 is also formed at the upper portion outside the rooting portion, the portion of the shaft portion 33 that is located outside the rooting portion is supported. The strength is the same as that of a normal pile having an outer diameter D ₀ (600 mm). Therefore, the strength of this part is about one half of the support strength of the high-strength root-solidified portion, and about 70% of the upper pile (700 mm) connected to the upper portion of the step portion 35 exhibits the support strength. I can't.

  Therefore, in order to make use of the strength of the root consolidation part and the pile material, it is optimal to embed the shaft part 33 and the step part 35 of the lower pile 32 in the root consolidation part.

  Further, the lower pile 32 is a bar arrangement in which a spiral reinforcing bar 38 is provided around the PC steel rods 37 and 37 arranged at equal intervals along the circle of the shaft portion 33 (FIG. 9A). b)).

  In the manufacture of the lower pile 32, a dedicated concave and convex formwork may be used, but a protrusion may be formed by attaching a taper to the inner surface of the formwork of a conventional cylindrical pile (straight pile). Yes (not shown).

Next, a pile hole 1 having a diameter D ₀₀ (= 780 mm) of the shaft portion 2 and a diameter D ₁₁ (= 1500 mm) of the bottom expanded portion 3 is excavated, and in the bottom expanded portion 3 of the pile hole 1 as in the first embodiment. Is injected with cement milk with a predetermined solidification strength (300 kg / cm ² ), filled with soil cement stirred and mixed with excavated soil, and cemented milk with solidification strength (200 kg / cm ² ) in the shaft portion 2 of the pile hole 1. Is mixed with the excavated soil and filled with soil cement (about 30 Kg / cm ² ) to the pile hole (FIG. 7A).

Subsequently, the lower pile 32 is rotated and lowered if necessary so as not to allow dirt to adhere to the pile surface (FIG. 7B), and the upper pile 30 is connected to the connecting portion 34 of the lower pile 32. Then, it is lowered (FIG. 7C). The lower pile 32 of the ready-made pile 4 is held in the expanded bottom portion 3 of the pile hole 1. Here, the bottom surface (lowermost end surface) 8 a of the lower pile 32 of the ready-made pile 4 is located at a height DH ₁ (about 60 cm) from the ground bottom surface 11 of the expanded bottom portion 3. Further, the step portion 35 of the connecting portion 34 of the lower pile 32 is located on the upper side in the bottom expanded portion 3 of the pile hole 1 and a gap DH ₂ (from the uppermost annular rib 6 to the uppermost horizontal plane X of the bottom expanded portion ( The connection surface 34 a (the lower edge 31 of the upper pile, the upper edge of the lower pile) is located inside the shaft portion 2 of the pile hole 1. By solidifying the soil cement, a pile structure 10 in which the ready-made pile 4 is embedded in the pile hole 1 is constructed (FIG. 7D).

  The pile structure 10 constructed in this manner is similar to the first embodiment, with respect to the vertical load, the bottom surface 8a, the surfaces 5a and 6a directed downward of the annular ribs 5 and 6, and the step portion 35 below. The directed surface acts to significantly increase the vertical load to be borne as compared to the first embodiment (FIG. 1 (c), FIG. 3 (b)). Further, similarly to the first embodiment, the surfaces 5b and 6b directed upward of the annular ribs 5 and 6 act on the pulling force, and a high pulling strength equal to or higher than that of the first embodiment can be obtained. (FIG. 1 (d), FIG. 3 (c)).

  In the above, the outer diameter of the upper pile 30 can be appropriately larger than the outer diameter of the shaft portion 33 of the lower pile 32, the bending moment of the shaft portion (upper pile 30) of the ready-made pile 4 is increased, and the pile hole 1 is expanded. The strength against the horizontal load and vertical load of the pile structure 10 at the pile hole 1 shaft portion 2 can be enhanced while maintaining the reinforcement as the pile structure 10 at the portion 3. Moreover, by making the outer diameter of the upper pile 30 larger than the outer diameter of the shaft portion 33 of the lower pile 32, the outer surface of the ready-made pile 4 (upper pile 30) and the inner surface of the pile hole 1 can be obtained by the pile hole 1 shaft portion 2. Can be reduced, and the usage amount of the pile fixing liquid in the pile hole 1 shaft portion 2 can be reduced. If the outer diameter of the upper pile 30 is made larger than the outer diameter of the shaft portion of the lower pile 32 and smaller than the outer diameter of the annular ribs 5 and 6 while strengthening the proof strength against horizontal load, vertical load, etc., the pile surface area Becomes smaller and the pile can be easily inserted.

  In the above-described embodiment, the lower pile 32 of the ready-made pile 4 is arranged only in the shaft portion 33, but reinforcing reinforcing bars such as deformed steel bars 39 and 39 are also arranged in the upper bulging connecting portion 34, and the ring It can also reinforce with the lines 40, 40 (FIGS. 10A and 10B).

  Thus, by arranging the deformed steel bars 39, 39 on the outer periphery of the PC steel bars 37, 37, it is possible to prevent the pile head from being broken against a vertical load and a horizontal force acting from a ground structure or the like. In addition, by arranging the deformed steel bar 39, it is possible to withstand an excessive horizontal force. The effect of the deformed steel bar 39 is the same as that described in detail in the fourth embodiment, and is not described in this embodiment. As in the fourth embodiment, a plurality of (for example, two types) of deformed reinforcing bars 39 having different lengths are prepared, and adjacent deformed reinforcing bars can have different lengths (FIG. 14 (c)). ).

  Further, the lower pile 32 can be reinforced by arranging the deformed steel bars 41 and 41 obliquely through the hollow portion 36 (so-called “X bar arrangement”) in the gap between the PC steel bars 37 and 37. (FIGS. 11A and 11B).

Moreover, in the said Example, although it is desirable for the upper pile 30 and the lower pile 32 to set intensity | strength in the range of 800-1000 kg / cm < ² > compressive strength, it can also be set as another intensity | strength.

Moreover, in the said Example, the inclination | tilt angle of the step part 35 of the lower pile 32 of the ready-made pile 4 can also be formed with the propagation angle (theta) ((theta) ₁ , (theta) _2, about 30 degrees) of axial force, and vertical load effect | action Although the step portion is sometimes desirable because it works more effectively (FIG. 8C), the angle of the step portion can be set arbitrarily. Moreover, the lower pile 32 can also form the connection part 42 which bulged in the lower end part similarly to the upper end part (FIG.8 (d)), and can further improve a support force and a drawing-out force in this case. .

  Moreover, in the said Example, the lower pile 32 of the ready-made pile 4 can also extend the connection part 34 upwards, and can also form it in length L (FIG.8 (b)). The length L is appropriately selected and set in consideration of the load of the upper pile 30 connected to the upper portion and the structure constructed on the upper portion of the pile structure 10. Moreover, if the length L of the connection part 34 is made into the length of the upper pile 30 required, it can also be set as an integrated ready-made pile as a single pile, the upper pile 30 is unnecessary, and a joint work can be omitted in construction. .

  Moreover, in the said Example, although the upper pile 30 and the lower pile 32 were made into the concrete pile, it can also be comprised by winding a steel pipe around the outer periphery of a concrete pile, or can also be set as the steel pipe pile of the same structure (not shown). ).

  (1) Another embodiment of the present invention will be described with reference to FIGS. In Example 3, in addition to strengthening the vertical load and pull-out force in the pile structure 10 of Example 1, the pile hole shaft part can also be strengthened to achieve a well-balanced reinforcement between the shaft part and the bottom expanded part as a whole pile structure. The construction efficiency was also improved. In the present embodiment, the high vertical bearing strength strength capability of the rooting portion is utilized to the maximum, and the production efficiency is enhanced.

(2) Configuration of ready-made pile The ready-made pile 4 of this embodiment is located in one or a plurality of upper piles 30 used for the portion located in the shaft portion 2 of the pile hole 1 and the bottom expanded portion 3 of the pile hole 1. It is the hollow concrete pile comprised from the lower pile 32 used for a part. The upper pile 30 has an outer shape D ₉ (= 700 mm), a wall thickness of 110 mm, and a concrete compressive strength of 850 kg / cm ² (FIG. 13A).

The lower pile 32 has a shaft portion (lower shaft portion) 33 outer diameter D ₀ (= 600 mm), a shaft portion thickness of 90 mm, an annular rib (outer diameter D ₁ = 750 mm) 5 at the lower end portion and the middle portion, 6 are formed, and the upper end portion forms a straight pile-shaped upper shaft portion 43 having an outer diameter D ₉ , and the upper end portion of the upper shaft portion 43 is a connection portion with the upper pile 30 (outer diameter D ₉ = 700 mm). ) 34 is formed, the inner thickness of the connecting portion is 140 mm, and the concrete compressive strength is 1000 kg / cm ² .

Since the upper shaft portion 43 is continuously formed integrally with the upper surface (located at the uppermost portion) of the annular rib 6, the shaft portion 33 does not appear in this portion as in the third embodiment. The upper shaft portion of the outer diameter D ₉ is an outer the diameter D ₁ is continuously formed in the (D _1> D _9), annular surface of the obliquely upward on the outer peripheral portion upper surface 6c of the annular rib 6 of the annular rib 6 Is formed (FIG. 13A).

    Here, the pile used as the upper pile 30 is usually one having a large amount of prestress, as in Example 3, so that the thickness of the upper and lower piles, the concrete compressive strength, etc. can be varied to increase the axial force strength. Are almost the same strength. The interval between the annular ribs 5 and 6 of the lower pile 32 is such that the annular rib 5 is formed at a position 500 mm from the bottom surface 8 a of the lower pile 32 and the annular rib 6 is formed at a position 1500 mm. Further, the lower pile 32 is a bar arrangement in which a spiral reinforcing bar 38 is provided around PC steel rods 37 and 37 arranged at equal intervals along the circle of the shaft portion 33. In addition, deformed reinforcing bars 44 and 44 fixed to the joint end plate 45 are annularly arranged at the upper end portion of the upper shaft portion 43 (FIGS. 14A and 14B).

As described above , by disposing the deformed steel bars 44, 44 on the outer periphery of the PC steel bars 37, 37, the pile head is prevented from being broken against a vertical load and a horizontal force acting from a ground structure or the like. be able to. Moreover, when it is set as a connection pile, this can be transmitted to the solidification part 3 substantially uniformly with respect to the vertical load which propagates from the upper pile 30 to the lower pile 32. At this time, it is desirable that the PC steel bar 37 bar arrangement position of the upper pile 30 and the deformed steel bar 44 bar arrangement position coincide. In addition, a helical rebar can be arranged around the deformed steel bar 44 (not shown).

  Further, by arranging the deformed steel bar 44, it is possible to withstand an excessive horizontal force. In addition, by preparing a plurality (for example, two types) of deformed reinforcing bars having different lengths and having adjacent deforming reinforcing bars of different lengths (FIG. 14 (b)), a load near the breaking load acts. When it does, it can prevent that a ready-made pile will be crushed at once.

The effect of the deformed steel bar 44 can be similarly achieved in the deformed steel bar 39 of the third embodiment.

In the production of pre SL under piles 32 may be used formwork dedicated uneven shape, although it is also possible to form the protruding portions by attaching a tapered inner surface of the mold of a conventional cylindrical pile (straight pile) (Not shown).

Further, (for the preparation of high bearing capacity piles ribbed) under piles 32 of the present invention, the outer diameter D ₉ cun method of the upper shaft portion 43, a small diameter than the outer diameter D ₁ dimension of the annular rib 5 and 6 Therefore, there is an advantage that it is possible to use a facility for easily manufacturing a conventional pile with an annular rib with a simple manufacturing form exchange, and to produce a flexible product quantitatively without constructing a new manufacturing line.

(3) Foundation pile embedding method / foundation pile structure Next, as in Example 3, a pile hole 1 having a diameter D ₀₀ (= 780 mm) of the shaft portion 2 and a diameter D ₁₁ (= 1100 mm) of the expanded bottom portion 3 is formed. After excavation, in the same manner as in Example 1, cement milk having a predetermined solidification strength (200 kg / cm ² ) is injected into the expanded bottom portion 3 of the pile hole 1 and filled with soil cement stirred and mixed with excavated soil. Cement milk having a solidification strength (200 kg / cm ² ) is poured into the shaft portion 2 of the hole 1 and stirred and mixed with the excavated soil, so that the soil cement (about 30 kg / cm ² ) is almost filled up to the hole of the pile (FIG. 12). (A)).

Subsequently, the lower pile 32 is rotated and lowered if necessary so as not to allow dirt to adhere to the pile surface (FIG. 12B), and the upper pile 30 is connected to the connecting portion 34 of the lower pile 32. Then, it is lowered (FIG. 12 (c)). The lower end portion of the lower pile 32 of the ready-made pile 4 is installed in the expanded bottom portion 3 of the pile hole 1. Here, the bottom surface (lowermost end surface) 8 a of the lower pile 32 of the ready-made pile 4 is located at a height DH ₁ (about 50 cm) from the ground bottom surface 11 of the expanded bottom portion 3. Further, a gap DH ₂ (about 50 cm) is provided from the uppermost annular rib 6 of the lower pile 32 to the uppermost horizontal plane X of the expanded bottom portion, and the connection surface 34a (the lower edge 31 of the upper pile, the upper edge of the lower pile) Is located in the shaft 2 of the pile hole 1. By solidifying the soil cement, a pile structure 10 in which the ready-made pile 4 is buried in the pile hole 1 is constructed (FIG. 12D).

    In the pile structure 10 constructed in this way, the surface directed downward from the bottom surface 8a and the surfaces 5a and 6a directed downward from the annular ribs 5 and 6 acts on the vertical load in the same manner as in the first embodiment. Thus, the vertical load to be borne can be significantly increased as compared to the first embodiment (FIG. 1 (c), FIG. 3 (b)). In this case, since the inclined step portion 35 is not formed as compared with the third embodiment, the number of the downwardly acting surfaces is small, but a sufficient effect can be obtained.

    In addition, with respect to the pulling force, the surface 5b directed upward of the annular rib 5 and the upward outer peripheral surface 6c of the annular rib 6 act to obtain a high pulling strength equal to or higher than that of the first embodiment ( FIG. 1 (d) and FIG. 3 (c)).

(4) Action (a) Action effect by not making the outer diameter of the upper shaft part 43 of the lower pile 32 larger than the rib outer diameter D ₁ (D ₉ ≦ D ₁ ):
When designing the pile foundation, the required vertical support force to support the building to be built is set first, so the structure of the rooting part (the bottom expansion part 3 of the pile hole 1) that bears most of the support force and its It is usual that other conditions such as horizontal force are adjusted based on the construction method.

    In this embodiment, as described above, the excavation work in the construction of the pile foundation is usually 10 to 50 m while first excavating the shaft portion 2 of the pile hole 1 from the ground and simultaneously kneading the excavated mud into the pile hole wall. The pile hole 1 shaft portion 2 is formed to a certain depth. Next, when the predetermined depth for forming the root solidified portion is reached, the excavation diameter is expanded within a range of several meters to obtain a root solidified portion having a predetermined size and shape, and cement milk having a required solidification strength is obtained by a predetermined method. Filled and constructed, it is constructed so that the support force of the root consolidation part can be expressed efficiently.

Therefore, in order to ensure the adhesion quality of the injected cement milk and the piles 32, 30, the excavation diameter of the shaft portion 2 of the pile hole 1 is the lower pile 32 with the annular ribs 5, 6 embedded in the root consolidation portion. It is a dimension necessary for the excavation mud to be smoothly buried without being fixed to the annular ribs 5 and 6 while the pile hole 1 shaft portion 2 is being laid down. The outer diameter (D ₁ ) of the 32 annular ribs is about 30 mm ”.

Therefore, for the same purpose, the outer diameter dimension D ₉ of the “upper shaft portion 43 (upper pile 30) of the lower pile 32” that can be embedded in the pile hole 1 shaft portion 2 is the annular rib 5 embedded in the rooting portion, It is more efficient to make the outer diameter (D ₉ ≦ D ₁ ) not larger than the outer diameter D _{1 of} 6 and use the excavation diameter of the pile hole 1 shaft portion 2 as it is instead of double excavation.

    For example, when using the “upper shaft portion 43 (upper pile 30)” having a larger diameter, it is necessary to excavate the large-diameter pile hole 1 shaft portion 2 over a depth 10 times or more that of the bottom expanded portion 3. However, the increase in the support diameter is small for increasing the excavation diameter of the shaft portion 2, and it is economically inefficient.

    Therefore, when the pile hole excavation depth is large and a plurality of ready-made piles 4 are connected to each other, the shaft diameter of the upper pile 30 embedded in the pile hole 1 shaft portion 2 and the lower pile 32 positioned at the root consolidation portion Since the shaft diameter of the upper shaft portion 43 is the same as that of the upper shaft portion 43 and is connected to each other, it is advantageous that the shaft diameter of the upper shaft portion 43 of the rooting portion is not larger than the outer diameter D of the annular ribs 5 and 6. .

That is, when the ready-made pile 4 is used as a single piece, the upper shaft portion 43 of the pile located in the upper end portion of the root-sealed portion is also located in the one shaft portion of the pile hole and is integrated (FIG. 13 (b)). for pile outer diameter of Uekui 30 located in the upper shaft portion 43 and the Kuiana first shaft portion 2 of the lower pile located root hardened portion are connected in the same dimension D ₉ (FIG. 13 (a)) .

(B) operation and effect of the diameter D ₉ of the upper shaft portion 43 which is larger than the shaft diameter D ₀ of the lower shaft portion 33:
The foundation pile 4 having an annular rib in the rooted portion has a high bearing capacity, and the bearing capacity is expressed by the upper and lower of the annular rib in order to utilize the support pressure of the annular rib in addition to the support force of the tip of the conventional pile. The peripheral portion is also covered with a cement milk layer having a predetermined solidification strength, and a strong root-solidified portion is formed by integrating the ready-made anti-resin and cement milk in the pile hole. That is, in order to fully develop the bearing pressure of the annular rib, it is necessary to make the cement milk solidified surface in contact with the annular rib as wide and thick as possible, in order to increase the diameter difference (D ₁ -D ₀ ). As a result, the shaft diameter D ₀ of the lower shaft portion 33 of the lower pile 32 is made as small as possible within the allowable range as a support force with respect to the outer diameter D ₁ of the annular rib.

    In addition, as a means for increasing the horizontal strength of the upper pile 30 (in the case of a single pile, the upper shaft portion 43), increasing the pile outer diameter increases the material strength of the pile or a higher strength pile. It is more economical than seeds, and the choice of both pile material and pile hole diameter is wide and advantageous.

Therefore, it is necessary to make the diameter D ₉ of the upper shaft portion 43 larger than the diameter D ₀ of the lower shaft portion 33 in order to make full use of the performance of the root-clamping portion, and to appropriately select the D ₉ size. It is easy and economical to adapt to the required bearing capacity of the building required by

(C) The effect which formed the upper axial part 43 of the lower pile 32 directly on the annular rib 6 located in the uppermost part:
The foundation pile that exhibits a high bearing capacity that positions the annular rib in the root consolidation part is used to express the bearing capacity using the support pressure of the annular rib in addition to the bearing capacity of the tip of the pile. In addition, it is thickly covered with a cement milk layer having a predetermined solidification strength to form a strong root-solidified portion in which the pile and cement milk are integrated. As a result, in the structure of the foundation pile, it has been confirmed by experiments that a vertical supporting force about twice as high as that of a cylindrical pile (straight shape) having the same outer diameter D ₀ can be obtained.

Therefore, if the pile positioned from the upper end of the pile hole rooting portion to the pile hole shaft portion is the same pile material as the lower shaft portion 33 (diameter D ₀ ) of the root hardening portion, It is difficult to make full use of the ability of the solidified part that has a low pile strength compared to the bearing capacity and exhibits high bearing capacity. Therefore, in order to make full use of the high vertical bearing strength strength capability of the root consolidation part, the pile material of the upper shaft part 43 (upper pile 30) is of high quality (generally expensive) with higher strength than the pile material of the root consolidation part. Although it is conceivable to use a pile material, it is necessary to connect with a large-diameter pile, so there are many technical problems and the construction is restricted.

  As this solution, although it can be solved as the lower pile 32 of the structure of FIG. 8D of the third embodiment, this method has to take a large depth of the root-solidified portion, and both the member cost and the construction cost are required. growing. In particular, the construction of the stepped portion of the pile due to the long stepped rooted pile, the handling during transportation, and the quality and reliability of the rooted portion need to be managed inherent in construction.

In order to solve this fundamental problem, the fourth embodiment has a structure in which the upper shaft portion 43 (large-diameter shaft portion D ₉ ) is integrally formed immediately above the annular rib 6 located at the uppermost portion.

  By using the above structure, it is easy to connect the cylindrical pile to the annular rib 6 within the above-mentioned size range by changing the formwork on the manufacturing equipment, so the shaft of the pile hole matched to the required support force for the building Selection of the part diameter becomes easy.

Since there is no small-diameter shaft portion 33 (shaft diameter D ₀ ) and stepped portion on the annular rib 6, the entire pile length can be shortened, and there is no pile portion with weak stress at all, which facilitates quality control such as manufacturing and construction. A simple and compacted structure pile was obtained.

  In addition, since the required pulling force is generally smaller than the vertical support force in the foundation pile, the bottom surfaces 5a and 6a of the two annular ribs 5 and 6 are used for the vertical support force, and the single pulling force is used. If the upper surface 5b of the annular rib 5 is used, it is practically possible.

Therefore, if the upper shaft portion 43 (shaft diameter D ₉₎ is formed directly from the upper side of the top of the annular rib 6, the vertical bearing capacity of the foundation anti together with the desired supporting force of the annular rib two pins is obtained The vertical support pressure in the annular rib 6 is further reinforced by the upper shaft portion 43 (large diameter) at the upper portion to improve the reliability.

  Further, the pulling force is almost borne by the support pressure of the annular rib 5, and the upper annular rib 6 hardly contributes. Therefore, there is no problem in practical use, and on the contrary, the structure is efficient. That is, the vertical support force and the pull-out force are practically balanced, and it is possible to develop a large horizontal support force and a vertical support force, and a pile foundation structure having a practical high support force that has never been obtained has been obtained.

(5) Reinforcement of the ready-made pile 32 The ready-made pile 32 is, for example, PC steel in the case of the ready-made pile 4 having a lower shaft diameter D ₀ = 600 mm, a protrusion diameter D ₁ = 750 mm, and an upper shaft diameter D ₉ = 700 mm. A plurality of rods 37 are arranged uniformly (annularly at regular intervals) so as to be positioned at a substantially central portion of the wall thickness 90 mm with a shaft diameter D ₀ (600 mm), and the outer periphery thereof is wound with a spiral reinforcing bar 38 to It is formed (FIG. 14C). At this time, the pitch of the spiral reinforcing bars 38 to be wound is preferably the same pitch over the entire length of the pile.

    Next, the upper and lower pile end plates are attached to both ends of the reinforcing bar cage. At this time, the shaped steel bars 44, 44 are attached to the pile end plate 45 on the upper shaft portion 43 side, and outside the PC steel bars 37, 37 and between the PC steel bars 37 and the PC steel bars 37. Arranged (FIG. 14A).

    Moreover, two types of lengths of the deformed steel bars 44, 44 are prepared (for example, 500 mm and 700 mm), and the deformed steel bars 44 having different lengths are arranged alternately (FIG. 14B). The deformed steel bar 44 can also be provided over the entire length of the upper shaft portion 43 (not shown).

    Thereafter, in the same manner as in the conventional method of manufacturing ready-made piles, the PC steel rods 37, 37 are pulled, prestressed, centrifugally formed, subjected to predetermined curing, and the ready-made piles 32, 4 of the present invention. Is completed (FIG. 14C).

A cylindrical pile having an outer diameter of 700 mm is formed on the upper end of the ready-made pile 32 (lower shaft diameter D ₀ = 600 mm, protrusion diameter D ₁ = 750 mm, upper shaft diameter D ₉ = 700 mm) formed by arranging the bars as described above. After being connected, a bending test was performed with two types of specimens having the same outer shape and the presence or absence of the deformed reinforcing bar 44.

    The ready-made pile provided with the deformed steel bar 44 was able to obtain a strength value about 1.5 times that of the ready-made pile provided with no deformed steel bar 44.

    From this, it is desirable to use a ready-made pile provided with a deformed steel bar 44, but it may be selected as appropriate in consideration of stress from the ground structure or the like.

(6) Other Examples In the above, the outer diameter of the upper pile 30 can be appropriately larger than the outer diameter of the shaft portion 33 of the lower pile 32, and the bending moment of the shaft portion (upper pile 30) of the ready-made pile 4 is increased. Thus, the strength against the horizontal load and vertical load of the pile structure 10 at the pile hole 1 shaft portion 2 can be enhanced while maintaining the reinforcement as the pile structure 10 at the pile hole 1 bottom expanded portion 3. Moreover, by making the outer diameter of the upper pile 30 larger than the outer diameter of the shaft portion 33 of the lower pile 32, the outer surface of the ready-made pile 4 (upper pile 30) and the inner surface of the pile hole 1 can be obtained by the pile hole 1 shaft portion 2. Can be reduced, and the usage amount of the pile fixing liquid in the pile hole 1 shaft portion 2 can be reduced. Moreover, if the outer diameter of the upper pile 30 is made larger than the outer diameter of the shaft portion of the lower pile 32 and smaller than the outer diameter of the annular ribs 5 and 6 while strengthening the proof strength against horizontal load, vertical load, etc., the pile surface area is reduced. Becomes smaller and the pile can be easily inserted.

    In the said Example, although the lower pile 32 of the ready-made pile 4 was arranged only to the axial part 33 similarly to Example 3, reinforcement of deformed steel bars 39 and 39 etc. also to the bulging connection part 34 of the upper part is carried out. Reinforcing bars can be arranged and reinforced by the ring bars 40, 40 (FIGS. 10A and 10B).

    Further, the lower pile 32 can be reinforced by arranging the deformed steel bars 41 and 41 obliquely through the hollow portion 36 (so-called “X bar arrangement”) in the gap between the PC steel bars 37 and 37. (FIGS. 11A and 11B).

Moreover, like the said Example 3, in the said Example, although it is desirable for the upper pile 30 and the lower pile 32 to set intensity | strength in the range of 800-1000 kg / cm < ² > compressive strength, it is set as other intensity | strength. You can also.

    Moreover, in the said Example, the lower pile 32 can also form the connection part 42 which bulged similarly to the upper end part also in the lower end part (FIG.13 (d)), and in this case, support force and extraction force are further provided. Can be improved.

Moreover, in the said Example, the cyclic | annular rib 7 can also be formed in the intermediate part of the upper axial part 43 (FIG.13 (c)). By providing the annular rib 7 on the upper shaft portion 43, the annular rib 7 is positioned on the shaft portion 2 of the pile hole 1. As a result, the surface area of the pile is increased, and the peripheral surface support force can be increased in the pile hole shaft portion 2. In addition to the support force in the pile hole root consolidation portion 3, the strength of the foundation pile structure as a whole is further increased. Will improve. Also, the annular rib 7 provided on the upper shaft portion 43, and by the outer diameter of the annular rib 7 of the upper shaft portion 43 is substantially the same at D _1, insert the ready-made pile 32 and 30 to Kuiana 1 drilled It is possible to prevent so-called eccentricity, in which the ready-made piles 32 and 30 are inclined.

    Moreover, in the said Example, like the said Example 3, the lower pile 32 of the ready-made pile 4 can also be extended in the connection part 34 and can be formed in length L (FIG.13 (b)). The length L is appropriately selected and set in consideration of the load of the upper pile 30 connected to the upper portion and the structure constructed on the upper portion of the pile structure 10. Moreover, if the length L of the connection part 34 is made into the length of the upper pile 30 required, it can also be set as an integrated ready-made pile as a single pile, the upper pile 30 is unnecessary, and a joint work can be omitted in construction. .

    Moreover, in the said Example, although the upper pile 30 and the lower pile 32 were made into a concrete pile like Example 3, it should be comprised by winding a steel pipe around the outer periphery of a concrete pile, or making it a steel pipe pile of the same structure. (Not shown).

Some vertical sectional view taken generally an example of the present invention, also while drilling Kuiana, state, also the pile (c) building the piles are embedded (b) also prefabricated pile into the pile hole (a) The figure explaining support force, (d) It is a figure explaining drawing force similarly . (A) partial front view of the prefabricated pile invention this is a cross-sectional view, cross-sectional view taken along the middle line B-B (c) also (a) in the middle line A-A (b) also (a). (A) partial longitudinal sectional front view of a pile structure constructed in Example of the invention this part longitudinal sectional front view of a fractured state when added to similarly load (b), when added to well pullout force (c) Explanatory drawing of the destruction state of . Similarly, in the pile structure of the comparative example, an explanatory diagram of a broken state when a load is applied is shown. (A) also partial front view of another embodiment of a ready-made pile, (b) also a cross-sectional view of the middle line C-C (a), cross-sectional view taken along the middle line D-D (c) also (a), ( it is a cross-sectional view in d) also (a) middle line E-E. Similarly, in another embodiment of the ready-made pile, (a) is also a partial front view, and (b) is also a partial bottom view. In longitudinal sectional view schematically illustrating the embedding method of the embodiment 3 of the present invention, are embedded (a) also of Kuiana that drilling Kuiana state, (b) (c) also prefabricated pile into the pile hole intermediate states is a state constructed (d) is also piles. Similarly (a) thru | or (d) are the front views of the ready-made pile used for Example 3. FIG. Similarly, (a) is an enlarged cross-sectional view of the ready-made pile used in Example 3, and (b) is a schematic front view illustrating the bar arrangement. Similarly, in another ready-made pile used in Example 3, (a) is an enlarged cross-sectional view, and (b) is a schematic front view for explaining bar arrangement. Similarly, in another ready-made pile used in Example 3, (a) is an enlarged cross-sectional view, and (b) is a schematic front view for explaining bar arrangement. It is the general | schematic longitudinal cross-sectional view explaining the embedding method of Example 4 of this invention, (a) is the state which excavated the pile hole, (b) (c) is the state in the middle of embedding the ready-made pile in the pile hole (D) is the state which built the pile. Similarly (a) thru | or (d) are the front views of the ready-made pile used for Example 4. FIG. Similarly, (a) is an enlarged cross-sectional view, (b) is a partial front view, and (c) is a schematic front view for explaining bar arrangement in the ready-made pile used in Example 4. (A) (b) is the partial longitudinal cross-sectional view which outlined the foundation pile structure of the prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pile hole 2 Shaft part of a pile hole 3 Expanded bottom part of a pile hole 4 Ready-made pile 5, 6, 7, 12 Annular rib (ready-made pile)
8 Shaft (ready-made pile)
8a Bottom of ready-made pile (bottom end)
10 Pile structure 11 Support ground surface (ground bottom)
16 Straight pile (conventional example)
18 Pile structure (conventional example)
21, 22, 23 Protrusion 24 ST pile (conventional example)
26 Pile hole (conventional example)
27 Shaft hole shaft (conventional example)
28 Expanded bottom of pile hole (conventional example)
30 Upper Pile 32 Lower Pile 33 Lower Pile Shaft 34 Lower Pile Connection 35 Lower Pile Step 37 PC Steel Bar 39 Deformed Steel Bar 43 Upper Pile of Lower Pile 44 Deformed Steel Bar

Claims (7)

Drilled Kuiana with拡底portion, to form a source-yl cement by injecting cement milk in the enlarged bottom portion, within said拡底portion, lowers the prefabricated pile having a projection on the lower end outer periphery, at least of said projections A method for embedding a prefabricated pile characterized in that one is fixed so as to be accommodated in the expanded bottom portion, and a predetermined gap is formed between the lower surface of the protrusion and the bottom of the ground of the expanded bottom portion of the pile hole.   Drilling a pile hole having an expanded bottom, injecting cement milk into the expanded bottom and stirring to form a soil cement with the excavated soil and cement milk, and forming a ready-made pile having a protrusion on the outer periphery of the lower end in the expanded bottom The protrusion is lowered and fixed so that at least one of the protrusions fits in the expanded bottom portion, and is located between the lower surface of the protrusion and the ground bottom surface of the pile hole expanded bottom portion, and between the upper surface of the protrusion and the pile hole expanded bottom portion. A method for burying a ready-made pile, wherein a predetermined gap is formed between the upper surface and the upper surface.   3. The method for embedding ready-made piles according to claim 1 or 2, wherein the cement milk has a strength such that the solidification strength of the soil cement is mechanically equal to or higher than that of the supporting ground.   The bottom of the pile hole is filled with a soil cement mixed with excavated soil and cement milk, and a pre-made pile having a protrusion on the outer periphery of the lower end is inserted and installed in the soil cement. A foundation pile in which at least one protrusion of the pile is inserted, and a predetermined gap is provided between a lower surface of the protrusion and a ground bottom surface of the expanded bottom portion, and the soil cement is filled. Construction.   A ready-made pile whose lower end is embedded in the expanded bottom portion of the pile hole, and is provided with a protrusion at a position having a predetermined gap from the ground bottom of the expanded bottom portion in the shaft portion entering the expanded bottom portion. Pile.   The ready-made pile according to claim 5, wherein the shaft portion of the pile that enters the pile hole other than the expanded bottom portion is straight, and one or more protrusions of the axial portion in the expanded bottom portion are provided.   The ready-made pile according to claim 4, wherein the ready-made pile is a joint pile or an integral pile, and one or more protrusions are provided on the pile shaft portion embedded in the pile hole shaft portion.