JP6171418B2 - Pile-foundation joint structure and method - Google Patents
Pile-foundation joint structure and method Download PDFInfo
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- JP6171418B2 JP6171418B2 JP2013046497A JP2013046497A JP6171418B2 JP 6171418 B2 JP6171418 B2 JP 6171418B2 JP 2013046497 A JP2013046497 A JP 2013046497A JP 2013046497 A JP2013046497 A JP 2013046497A JP 6171418 B2 JP6171418 B2 JP 6171418B2
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Description
本発明は、杭と基礎との接合構造及び方法に関する。 The present invention relates to a joining structure and method of a pile and a foundation.
地震時の水平力により杭頭部と基礎との接合部に生じる曲げモーメントを緩和することを目的として、杭頭部を基礎に埋設せずに基礎の底面に接するように配し、杭頭部と基礎とをこれらに跨る鉄筋で接合したものが知られている（例えば、特許文献１、２参照）。特許文献１に記載の杭と基礎との接合構造では、上記鉄筋の全体を杭頭部と基礎とに付着させることにより杭頭部と基礎とを接合している。また、特許文献２に記載の杭と基礎との接合構造では、杭頭部に生じた曲げモーメントによる杭頭部のコンクリートの圧壊を抑制することを目的として、杭頭部に位置する上記鉄筋の中間部分を杭頭部に付着させない付着切り部としている（図７参照）。 In order to alleviate the bending moment generated at the joint between the pile head and the foundation due to the horizontal force during an earthquake, the pile head is placed in contact with the bottom of the foundation without being embedded in the foundation. And a foundation joined with a reinforcing bar that straddles them are known (see, for example, Patent Documents 1 and 2). In the joint structure of the pile and the foundation described in Patent Document 1, the pile head and the foundation are joined by attaching the entire reinforcing bar to the pile head and the foundation. Moreover, in the joining structure of the pile and foundation described in Patent Document 2, for the purpose of suppressing concrete collapse of the pile head due to the bending moment generated in the pile head, The intermediate portion is an attachment cut portion that does not attach to the pile head (see FIG. 7).
特許文献１、２に記載の杭と基礎との接合構造では、地震時にせん断力を基礎から杭頭部へ上記鉄筋を介して伝達させることはできるが、上記鉄筋の全体又は中間部分以外が基礎と杭頭部とに付着されており、杭頭部が基礎に上記鉄筋を介して拘束されている。このため、地震時に杭頭部の回転が妨げられ、杭頭部と基礎との接合部に生じる曲げモーメントを効果的に緩和することができない。 In the joint structure of the pile and the foundation described in Patent Documents 1 and 2, shear force can be transmitted from the foundation to the pile head through the reinforcing bar during an earthquake, but the whole or other than the intermediate part of the reinforcing bar is the foundation. The pile head is constrained to the foundation via the reinforcing bars. For this reason, rotation of a pile head is prevented at the time of an earthquake, and the bending moment which arises in the junction part of a pile head and a foundation cannot be relieved effectively.
本発明は、上記事情に鑑みてなされたものであり、基礎から杭へのせん断力の伝達性能を確保すると共に、地震時に杭頭部と基礎との接合部に生じる曲げモーメントを効果的に緩和することを課題とするものである。 The present invention has been made in view of the above circumstances, and while ensuring the transmission performance of the shearing force from the foundation to the pile, it effectively reduces the bending moment generated at the joint between the pile head and the foundation during an earthquake. It is an object to do.
上記課題を解決するために、本発明に係る杭と基礎との接合構造は、杭頭部が基礎底面に直接接し、又は、シート状の縁切り層を介して接するように、かつ前記基礎底面から離間可能に配され、複数の丸鋼が間隔をおいて杭頭部と基礎とに跨るように配された杭と基礎との接合構造であって、前記複数の丸鋼の杭頭部に配された部分の全体と前記複数の丸鋼の基礎に配された部分の全体との少なくとも一方は、当該部分が配された杭頭部又は基礎と付着しないように構成されていることを特徴とする。 In order to solve the above problems, the joint structure between the pile and the base according to the present invention, pile head is direct contact to the base bottom surface, or to contact through the sheet-like edge cutting layer and said base A pile-foundation structure in which a plurality of round bars are arranged so as to be separable from the bottom surface, and are arranged so as to straddle the pile head and the foundation at intervals, the pile heads of the plurality of round steels That at least one of the entire portion disposed on the foundation and the entire portion disposed on the foundation of the plurality of round steel bars is configured not to adhere to the pile head or the foundation on which the portion is disposed. Features.
上記杭と基礎との接合構造において、杭は既製杭であってもよく、その場合、前記丸鋼は、前記既製杭の頭部に打設された中詰めコンクリートに配されてもよい。 In the joint structure between the pile and the foundation, the pile may be a ready-made pile, and in that case, the round steel may be disposed on the filling concrete placed on the head of the ready-made pile.
上記杭と基礎との接合構造において、前記既製杭は既製コンクリート杭であってもよい。 In the joint structure between the pile and the foundation, the ready-made pile may be a ready-made concrete pile.
また、本発明に係る杭と基礎との接合方法は、杭頭部を基礎底面に直接接し、又は、シート状の縁切り層を介して接するように、かつ前記基礎底面から離間可能に配し、複数の丸鋼を間隔をおいて杭頭部と基礎とに跨るように配する杭と基礎との接合方法であって、前記複数の丸鋼の杭頭部に配する部分の全体と前記複数の丸鋼の基礎に配する部分の全体との少なくとも一方を、当該部分を配する杭頭部又は基礎と付着しないように構成して、前記丸鋼に作用する引張力を低減させることにより前記丸鋼のせん断力に対する耐力を高めることを特徴とする。 Further, method of joining the pile and the base according to the present invention, the pile head and direct contact to the underlying bottom surface, or to contact through the sheet-like edge cutting layer, and separably distribution from said base bottom surface And a method of joining the pile and the foundation to arrange the plurality of round steels so as to straddle the pile head and the foundation at intervals, and the whole portion to be arranged on the pile heads of the plurality of round steels , Configuring at least one of the entire portions disposed on the plurality of round steel foundations so as not to adhere to a pile head or foundation on which the portions are disposed, and reducing a tensile force acting on the round steel. Thus, the yield strength against the shearing force of the round steel is increased.
本発明によれば、基礎から杭へのせん断力の伝達性能を確保すると共に、地震時に杭頭部と基礎との接合部に生じる曲げモーメントを効果的に緩和することができる。 ADVANTAGE OF THE INVENTION According to this invention, while ensuring the transmission performance of the shearing force from a foundation to a pile, the bending moment which arises in the junction part of a pile head and a foundation at the time of an earthquake can be relieve | moderated effectively.
以下、本発明の一実施形態を、図面を参照しながら説明する。図１は、一実施形態に係る杭２０と基礎３０との接合構造１０を示す立断面図である。この図に示すように、接合構造１０では、ＰＨＣ杭やＰＲＣ杭等の既製コンクリート杭である杭２０の頭部が、基礎３０に埋設されるのではなく、ビニールシート等の縁切り材４０を介して基礎３０の底面３１に接するように配されている。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Drawing 1 is an elevation sectional view showing joined structure 10 of pile 20 and foundation 30 concerning one embodiment. As shown in this figure, in the joint structure 10, the head of the pile 20, which is a ready-made concrete pile such as a PHC pile or a PRC pile, is not embedded in the foundation 30, but via an edge cutting material 40 such as a vinyl sheet. Are arranged in contact with the bottom surface 31 of the foundation 30.
また、接合構造１０では、杭２０の頭部には、中詰めコンクリート２２が打設されており、丸鋼である複数の差筋５０が、中詰めコンクリート２２と基礎３０とに跨るように配されている。なお、複数の差筋５０は、平面視における縦横（紙面における左右方向及び奥行方向）に並べて配されている。 Further, in the joint structure 10, the filling concrete 22 is placed on the head of the pile 20, and a plurality of differential bars 50 made of round steel are arranged so as to straddle the filling concrete 22 and the foundation 30. Has been. The plurality of difference bars 50 are arranged side by side in the vertical and horizontal directions (left and right direction and depth direction in the drawing).
杭２０の天端面２１には鋼製のキャップ２３が取り付けられており、該キャップ２３の内側において、縁切り材４０からなる縁切り層が、中詰めコンクリート２２と基礎３０との間に介在している。 A steel cap 23 is attached to the top end surface 21 of the pile 20, and an edge cutting layer made of the edge cutting material 40 is interposed between the filling concrete 22 and the foundation 30 inside the cap 23. .
ここで、差筋５０の上側は基礎３０内に下側は中詰めコンクリート２２内に配されているが、差筋５０の上側と基礎３０のコンクリート、及び差筋５０の下側と中詰めコンクリート２２とは、これらの間にグリース等の潤滑剤を介在させること等により、付着しないように構成されている。 Here, the upper side of the difference bar 50 is arranged in the foundation 30 and the lower side is arranged in the filling concrete 22. However, the upper side of the difference bar 50 and the concrete of the foundation 30, and the lower side of the difference bar 50 and the filling concrete. 22 is configured so as not to adhere by interposing a lubricant such as grease between them.
図２及び図３は、杭２０と基礎３０との接合部の施工手順を示す立断面図である。まず、図２に示すように、杭２０を打設してその頭部に中詰めコンクリート２２を打設する。この際、中詰めコンクリート２２は、杭２０の頭部に型枠を設置して打設したり、杭２０内に頭部を残して土砂を詰めてその上に打設したりする等、従来から知られている方法により打設する。 2 and 3 are elevation sectional views showing a construction procedure of a joint portion between the pile 20 and the foundation 30. FIG. First, as shown in FIG. 2, the pile 20 is placed and the filling concrete 22 is placed on the head. At this time, the filling concrete 22 is conventionally placed by placing a formwork on the head of the pile 20, or leaving the head in the pile 20, stuffing earth and sand, and placing on the top. It is placed by the method known from
次に、図３に示すように、中詰めコンクリート２２が硬化する前に差筋５０の下側を中詰めコンクリート２２に挿入し、中詰めコンクリート２２上にビニールシート等の縁切り材４０を敷設する。この際、差筋５０にグリース等の潤滑剤を塗布することにより、硬化後の中詰めコンクリート２２と差筋５０の下側とが付着しないようにする。 Next, as shown in FIG. 3, before the filling concrete 22 is cured, the lower side of the differential bar 50 is inserted into the filling concrete 22, and an edge cutting material 40 such as a vinyl sheet is laid on the filling concrete 22. . At this time, a lubricant such as grease is applied to the differential reinforcement 50 so that the solidified concrete 22 after curing and the lower side of the differential reinforcement 50 do not adhere.
そして、杭２０の上に基礎３０を構築する。この際、図１に示すように、杭２０の頭部が基礎３０に埋設されずに縁切り材４０を介して基礎３０の底面３１に接するように、基礎３０のコンクリートを打設する。また、差筋５０にグリース等の潤滑剤を塗布することにより、硬化後の基礎３０のコンクリートと差筋５０の上側とが付着しないようにする。 Then, the foundation 30 is constructed on the pile 20. At this time, as shown in FIG. 1, the concrete of the foundation 30 is placed so that the head of the pile 20 is not embedded in the foundation 30 and is in contact with the bottom surface 31 of the foundation 30 via the edge cutting member 40. Further, a lubricant such as grease is applied to the differential bar 50 so that the concrete of the foundation 30 after curing and the upper side of the differential bar 50 do not adhere.
図４は、本実施形態に係る杭２０と基礎３０との接合構造１０の作用を示す立断面図である。この図に示すように、地震時に杭２０と基礎３０との接合部に対して水平力が作用した場合、差筋５０の上下が基礎３０と中詰めコンクリート２２に差し込まれていることにより、基礎３０から杭２０の頭部へせん断力Ｐが伝達される。即ち、差筋５０のダボ効果により、基礎３０と杭２０の頭部との間のせん断力Ｐの伝達性が確保される。 FIG. 4 is an elevational sectional view showing an operation of the joint structure 10 between the pile 20 and the foundation 30 according to the present embodiment. As shown in this figure, when a horizontal force is applied to the joint between the pile 20 and the foundation 30 during an earthquake, the top and bottom of the differential bar 50 is inserted into the foundation 30 and the filled concrete 22 so that the foundation Shear force P is transmitted from 30 to the head of the pile 20. That is, due to the dowel effect of the differential bar 50, the transmission of the shearing force P between the foundation 30 and the head of the pile 20 is ensured.
また、基礎３０から杭２０の頭部へせん断力Ｐが伝達されて、杭２０が頭部を支点として回転しようとする際、差筋５０が、中詰めコンクリート２２に付着しておらず、中詰めコンクリート２２に対して相対的に上下に動くことにより、杭２０の回転を妨げない。これにより、杭２０の頭部と基礎３０との固定度を効果的に低下させることができ、地震時に杭２０の頭部と基礎３０との接合部に生じる曲げモーメントを効果的に低下させることができる。従って、杭２０や基礎３０に要求される耐力を抑えることができるため、杭２０や基礎３０の断面の増大や鉄筋の配筋量の増加を抑えることができる。 Further, when the shear force P is transmitted from the foundation 30 to the head of the pile 20 and the pile 20 tries to rotate with the head as a fulcrum, the difference bar 50 is not attached to the filling concrete 22 and By moving up and down relatively with respect to the stuffed concrete 22, the rotation of the pile 20 is not hindered. Thereby, the fixing degree of the head of the pile 20 and the foundation 30 can be effectively reduced, and the bending moment generated at the joint between the head of the pile 20 and the foundation 30 during an earthquake can be effectively reduced. Can do. Therefore, since the proof stress requested | required of the pile 20 and the foundation 30 can be suppressed, the increase in the cross section of the pile 20 or the foundation 30 and the increase in the amount of reinforcement arrangement | positioning can be suppressed.
特に、本実施形態では、差筋５０の上側についても基礎３０に付着させず、また、杭２０の天端面２１と基礎３０の底面３１との間に縁切り材４０を設けてこれらを離間し易く構成したことにより、杭２０の頭部と基礎３０との固定度をより一層効果的に低下させることができ、地震時に杭２０の頭部と基礎３０との接合部に生じる曲げモーメントをより一層効果的に低下させることができる。 In particular, in this embodiment, the upper side of the differential bar 50 is not attached to the foundation 30, and the edge cutting member 40 is provided between the top end surface 21 of the pile 20 and the bottom surface 31 of the foundation 30 to easily separate them. By comprising, the fixing degree of the head of the pile 20 and the foundation 30 can be reduced more effectively, and the bending moment which arises in the junction part of the head of the pile 20 and the foundation 30 at the time of an earthquake is further increased. It can be effectively reduced.
ここで、図５に示すように、異形鉄筋５１を杭２０及び基礎３０に付着させた場合には、当該異形鉄筋５１にはせん断力Ｑのみならず、引張力Ｒも作用するため、当該異形鉄筋５１のせん断力Ｑに対する耐力が低下する。これに対して、本実施形態では、差筋５０を杭２０や基礎３０に付着させないようにしたことにより、差筋５０に作用する引張力を低減させることができ、これにより、差筋５０のせん断力に対する耐力を高めることができる。 Here, as shown in FIG. 5, when the deformed reinforcing bar 51 is attached to the pile 20 and the foundation 30, not only the shearing force Q but also the tensile force R acts on the deformed reinforcing bar 51. The proof stress with respect to the shearing force Q of the reinforcing bar 51 is reduced. On the other hand, in the present embodiment, the tensile force acting on the differential bar 50 can be reduced by preventing the differential bar 50 from adhering to the pile 20 or the foundation 30, and thereby, The resistance to shearing force can be increased.
本実施形態に係る杭２０と基礎３０との接合構造１０の効果を確認するための実験を実施したので、以下説明する。図６は、不静定柱加力形式の載荷試験の概略を示す図であり、図７は、片持ち柱加力形式の載荷試験の概略を示す図である。また、図８は、両試験での試験体の仕様をまとめた表である。 Since the experiment for confirming the effect of the joint structure 10 of the pile 20 and the foundation 30 according to the present embodiment was performed, the following description will be given. FIG. 6 is a diagram showing an outline of a loading test in a static column force type, and FIG. 7 is a diagram showing an outline of a loading test in a cantilever column force type. FIG. 8 is a table summarizing the specifications of the specimens in both tests.
図６に示す不静定柱加力形式の載荷試験は、杭３と基礎５との接合部の界面でのせん断耐力を把握することを目的として、図８の表中の試験体Ｎｏ１〜４を用いて実施した。一方、図７に示す片持ち柱加力形式の載荷試験は、杭２０と基礎３０との接合部における曲げモーメントＭと杭頭部の回転角θとの関係を把握することを目的として、図８の表中の試験体Ｎｏ５，６を用いて実施した。 The load test of the statically indeterminate column force type shown in FIG. 6 is for the purpose of grasping the shear strength at the interface of the joint portion between the pile 3 and the foundation 5, and the test bodies No1 to No.4 in the table of FIG. It carried out using. On the other hand, the loading test of the cantilever column force type shown in FIG. 7 is performed for the purpose of grasping the relationship between the bending moment M at the joint between the pile 20 and the foundation 30 and the rotation angle θ of the pile head. It implemented using the test body No5 and 6 in the table | surface of 8. FIG.
図８の表に示すように、試験体Ｎｏ１〜６の杭３は、直径５００ｍｍ、厚さ８０ｍｍ、コンクリート強度が１０５Ｎ／ｍｍ２のＰＲＣ杭である。また、基礎５及び中詰めコンクリート４には、呼び強度が２１Ｎ／ｍｍ２のコンクリートを用い、スタブ部分２には、呼び強度が３６Ｎ／ｍｍ２のコンクリートを用いた。また、基礎５の寸法は、試験体Ｎｏ１〜４では１２５０×１２５０ｍｍ、試験体Ｎｏ５では１０００×１０００ｍｍ、試験体Ｎｏ６では１１００×１１００ｍｍである。さらに、中詰めコンクリート４の深さは、１／２Ｄとして２５０ｍｍとした。なお、試験体Ｎｏ１〜４は、接合部界面のせん断耐力を把握することを目的とすることから、基礎５での破壊を防止できるように杭心から基礎５の縁までの距離を１．２５Ｄ（Ｄ：杭径）とした。 As shown in the table of FIG. 8, the piles 3 of the test bodies No 1 to 6 are PRC piles having a diameter of 500 mm, a thickness of 80 mm, and a concrete strength of 105 N / mm 2 . The foundation 5 and the filling concrete 4 were concrete having a nominal strength of 21 N / mm 2 , and the stub portion 2 was concrete having a nominal strength of 36 N / mm 2 . Further, the dimensions of the foundation 5 are 1250 × 1250 mm for the test bodies No 1 to 4, 1000 × 1000 mm for the test body No 5, and 1100 × 1100 mm for the test body No 6. Furthermore, the depth of the filling concrete 4 was set to 250 mm as 1 / 2D. In addition, since test body No1-4 aims at grasping | ascertaining the shear strength of a junction interface, the distance from a pile center to the edge of the foundation 5 is 1.25D ( D: pile diameter).
差筋６は、φ２０、２５、１６ｍｍの丸鋼（ＳＮＲ４９０）であり、試験体Ｎｏ１〜５では矩形状に配筋し、試験体Ｎｏ６では円形に配筋した。試験体Ｎｏ１では、φ２０ｍｍの差筋６を４本、試験体Ｎｏ２、４では、φ２０ｍｍの差筋６を９本、試験体Ｎｏ３、５では、φ２５ｍｍの差筋６を９本、試験体Ｎｏ８では、φ１６ｍｍの差筋６を８本配筋した。中詰めコンクリート４の断面積に対する差筋６の断面積の割合（以下、差筋量という）は、試験体Ｎｏ１〜３では夫々１．３８％、３．１１％、４．８７％であり、試験体Ｎｏ４〜６では夫々３．１１％、４．８７％、１．７７％である。さらに、差筋６の基礎５への挿入長さは７ｄ（ｄ：差筋６の直径）であり、差筋６の中詰めコンクリート４への挿入長さはＤ／２かつ７ｄ＋４０ｍｍ以上である。 The difference bar 6 is a round steel (SNR490) of φ20, 25, and 16 mm, and the specimens No. 1 to No. 5 were arranged in a rectangular shape, and the specimen No. 6 was arranged in a circular shape. In specimen No. 1, four differential muscles 6 with a diameter of 20 mm are used. For specimens No. 2 and 4, nine differential muscles 6 with a diameter of 20 mm are provided. In specimens No. 3 and 5, nine differential bars 6 with a diameter of 25 mm are provided. , 8 differential bars 6 having a diameter of 16 mm were arranged. The ratio of the cross-sectional area of the differential bar 6 to the cross-sectional area of the filling concrete 4 (hereinafter referred to as the differential bar amount) is 1.38%, 3.11%, and 4.87% in the specimens Nos. 1 to 3, respectively. In the specimens Nos. 4 to 6, they are 3.11%, 4.87% and 1.77%, respectively. Furthermore, the insertion length of the differential bar 6 into the foundation 5 is 7d (d: the diameter of the differential bar 6), and the insertion length of the differential bar 6 into the filling concrete 4 is D / 2 and 7d + 40 mm or more.
ここで、試験体Ｎｏ４は、接合部界面のせん断耐力に対する基礎５の浮き上がりの影響を把握することを目的として、基礎５と杭３との間に３０ｍｍの隙間を設けた。また、試験体Ｎｏ５、６には夫々、２５００ｋＮ（σｎ＝２３．７Ｎ／ｍｍ２）、１０００ｋＮ（σｎ＝９．５Ｎ／ｍｍ２）の軸力Ｔを載荷した。 Here, test body No4 provided the 30 mm clearance gap between the foundation 5 and the pile 3 in order to grasp | ascertain the influence of the raising of the foundation 5 with respect to the shear strength of a junction part interface. Further, each of the specimens No5,6, 2500kN (σ n = 23.7N / mm 2), and loading an axial force T of 1000kN (σ n = 9.5N / mm 2).
図６及び図７に示すように、本実験では、軸力用のジャッキと水平載荷用のジャッキとの荷重をロードセルにより計測し、スタブ部分２に固定した計測治具により各載荷点および杭頭部周辺の水平・鉛直変位を計測した。下記（１）式で示すように、本実験において変形角Ｒは、中腹部水平載荷点（接合部界面からの高さｈ＝５５０ｍｍ）の水平変位δｈを高さｈで除した値と定義する。
As shown in FIGS. 6 and 7, in this experiment, the load of the axial force jack and the horizontal loading jack are measured by a load cell, and each loading point and pile head are measured by a measuring jig fixed to the stub portion 2. The horizontal and vertical displacement around the head was measured. As shown in the following equation (1), in this experiment, the deformation angle R is defined as a value obtained by dividing the horizontal displacement δ h at the horizontal loading point (height h = 550 mm from the joint interface) by the height h. To do.
また、軸力を載荷した試験体Ｎｏ５、６においては、軸力用のジャッキを受ける球座の水平変位δＴを計測し、軸力による付加曲げモーメントを考慮して杭頭曲げモーメントを算定した。 In the specimens No5,6 that loading axial force, by measuring the horizontal displacement [delta] T of ball seat for receiving a jack for axial force were calculated Pile Head bending moment considering the additional bending moment due to the axial force .
図９〜図１２は、試験体Ｎｏ１〜４の実験結果を示すグラフである。これらのグラフの横軸は変形角Ｒ（×１０−３ｒａｄ）を示し、縦軸は杭頭部のせん断力（ｋＮ）を示す。これらのグラフに示すように、差筋量が増えるほど接合部界面でのせん断耐力が増加することを確認できる。従って、差筋６によって基礎５から杭３へ十分にせん断力が伝達されると言える。 9-12 is a graph which shows the experimental result of test body No1-4. The horizontal axis of these graphs indicates the deformation angle R (× 10 −3 rad), and the vertical axis indicates the shear force (kN) of the pile head. As shown in these graphs, it can be confirmed that the shear strength at the joint interface increases as the amount of the differential reinforcement increases. Therefore, it can be said that the shear force is sufficiently transmitted from the foundation 5 to the pile 3 by the differential bar 6.
図１３は、試験体Ｎｏ５、６の実験結果を示すグラフである。このグラフの横軸は変形角Ｒ（×１０−３ｒａｄ）を示し、縦軸は杭頭曲げモーメント（ｋＮｍ）を示す。また、グラフ中の破線は、図５の比較例で示すようにダボ鉄筋を杭と基礎とに定着させた場合の杭頭曲げモーメントの計算値であり、グラフ中の太線は、ダボ鉄筋が付着していない場合の杭頭曲げモーメントの計算値である。これらの計算値は、平面保持を仮定したファイバーモデルを用いて計算した値である。そして、グラフ中の細線は、杭頭曲げモーメントの実験値である。 FIG. 13 is a graph showing the experimental results of specimens Nos. 5 and 6. The horizontal axis of this graph indicates the deformation angle R (× 10 −3 rad), and the vertical axis indicates the pile head bending moment (kNm). The broken line in the graph is the calculated value of the pile head bending moment when the dowel reinforcement is fixed to the pile and the foundation as shown in the comparative example of FIG. 5, and the thick line in the graph is the attachment of the dowel reinforcement It is the calculated value of the pile head bending moment when not. These calculated values are values calculated using a fiber model that assumes plane retention. And the thin line in a graph is an experimental value of a pile head bending moment.
このグラフに示すように、杭頭曲げモーメントの実験値と、ダボ鉄筋が付着していない場合の杭頭曲げモーメントの計算値（最大値）とはほぼ一致することを確認できる。従って、せん断抵抗材を差筋として杭と基礎とに定着させないようにしたことで、効果的に杭頭曲げモーメントを低減できると言える。 As shown in this graph, it can be confirmed that the experimental value of the pile head bending moment and the calculated value (maximum value) of the pile head bending moment when the dowel reinforcing bar is not attached substantially coincide. Therefore, it can be said that the pile head bending moment can be effectively reduced by preventing the shear resistance material from being fixed to the pile and the foundation as a differential bar.
なお、上述の実施形態は、本発明の理解を容易にするためのものであり、本発明を限定するものではない。本発明はその趣旨を逸脱することなく、変更、改良され得ると共に本発明にはその等価物が含まれることは勿論である。例えば、上述の実施形態では、既製杭として既製コンクリート杭を例に挙げて本発明を説明したが、既製杭としての鋼管杭にも本発明を適用できる。また、杭として既製コンクリート杭を例に挙げて本発明を説明したが、杭としての場所打ちコンクリート杭にも本発明を適用できる。さらに、単杭に限らず、壁杭にも本発明を適用できる。 In addition, the above-mentioned embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof. For example, in the above-described embodiment, the present invention has been described by taking a ready-made concrete pile as an example of a ready-made pile, but the present invention can also be applied to a steel pipe pile as a ready-made pile. Although the present invention has been described by taking a ready-made concrete pile as an example of the pile, the present invention can also be applied to a cast-in-place concrete pile as a pile. Furthermore, this invention is applicable not only to a single pile but to a wall pile.
また、上述の実施形態では、せん断抵抗材として丸鋼を例に挙げたが、ＣＦＲＰ製の棒材等の他のせん断抵抗材も適用できる。また、せん断抵抗材と杭及び基礎とを付着させないために、これらの間にグリース等の潤滑剤を介在させることは必須ではなく、該潤滑剤を介在させなくても、せん断抵抗材と杭及び基礎とが付着しないのであれば、該潤滑剤を省略してもよい。さらに、せん断抵抗材を杭及び基礎の双方に付着させないことは必須ではなく、杭には付着させずに基礎には付着させたり、杭には付着させるが基礎には付着させなかったりしてもよい。 Moreover, in the above-mentioned embodiment, although the round steel was mentioned as an example as a shear resistance material, other shear resistance materials, such as a bar material made from CFRP, are applicable. Further, in order to prevent the shear resistance material and the pile and the foundation from adhering, it is not essential to interpose a lubricant such as grease between them, and even if the lubricant is not interposed, the shear resistance material and the pile and If the foundation does not adhere, the lubricant may be omitted. Furthermore, it is not essential that the shear resistance material does not adhere to both the pile and the foundation, even if it adheres to the foundation without adhering to the pile or adheres to the pile but not to the foundation. Good.
また、上述の実施形態では、杭の天端面と基礎の底面との間の縁切り層を、シート状の縁切り材により構成したが、中詰めコンクリートと基礎のコンクリートとを打ち分けて、中詰めコンクリートと基礎の底面とに表面処理を施して離間し易いように構成してもよい。さらに、杭の天端面と基礎の底面との間に縁切り層を形成することは必須ではない。 Moreover, in the above-mentioned embodiment, the edge cutting layer between the top end face of the pile and the bottom face of the foundation is configured by a sheet-like edge cutting material. However, the filling concrete is divided into the filling concrete and the filling concrete. And a bottom surface of the foundation may be subjected to surface treatment so as to be easily separated. Furthermore, it is not essential to form an edge cutting layer between the top end face of the pile and the bottom face of the foundation.
２ スタブ部分、３ 杭、４ 中詰めコンクリート、５ 基礎、６ 差筋、１０ 接合構造、２０ 杭、２１ 天端面、２２ 中詰めコンクリート、２３ キャップ、３０ 基礎、３１ 底面、４０ 縁切り材（縁切り層）、５０ 差筋（せん断抵抗材）、５１ 異形鉄筋 2 Stub part, 3 pile, 4 fill concrete, 5 foundation, 6 differential bars, 10 joint structure, 20 pile, 21 top end face, 22 fill concrete, 23 cap, 30 foundation, 31 bottom, 40 edge cutting material (edge cutting layer) ), 50 differential bars (shear resistance material), 51 deformed bars
Claims (4)
前記複数の丸鋼の杭頭部に配された部分の全体と前記複数の丸鋼の基礎に配された部分の全体との少なくとも一方は、当該部分が配された杭頭部又は基礎と付着しないように構成されていることを特徴とする杭と基礎との接合構造。 Pile head is direct contact to the base bottom surface, or to contact through the sheet-like edge cutting layer, and arranged so as to be spaced from said base bottom surface, a pile head a plurality of round steel is at a distance It is a joint structure between a pile and a foundation arranged so as to straddle the foundation,
At least one of the entire portion disposed on the plurality of round steel pile heads and the entire portion disposed on the plurality of round steel foundations is attached to the pile head or foundation on which the portions are disposed. A pile-to-foundation structure characterized by being configured not to
前記複数の丸鋼は、前記既製杭の頭部に打設された中詰めコンクリートに配されていることを特徴とする請求項１に記載の杭と基礎との接合構造。 The pile is a ready-made pile,
The pile-foundation structure according to claim 1, wherein the plurality of round steel bars are arranged in an inside-filled concrete placed on a head of the ready-made pile.
前記複数の丸鋼の杭頭部に配する部分の全体と前記複数の丸鋼の基礎に配する部分の全体との少なくとも一方を、当該部分を配する杭頭部又は基礎と付着しないように構成して、前記丸鋼に作用する引張力を低減させることにより前記丸鋼のせん断力に対する耐力を高めることを特徴とする杭と基礎との接合方法。 The pile head and direct contact to the underlying bottom surface, or to contact through the sheet-like edge cutting layer, and separably disposed from said base bottom surface, and pile head at intervals a plurality of round bars A method of joining a pile and a foundation arranged so as to straddle the foundation,
At least one of the entire portion disposed on the plurality of round steel pile heads and the entire portion disposed on the plurality of round steel foundations is not attached to the pile head or the foundation on which the portions are disposed. A method for joining a pile and a foundation characterized in that, by reducing the tensile force acting on the round steel, the yield strength against the shearing force of the round steel is increased .
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