JPS60173215A - Construction work of cast-in-place pile - Google Patents

Abstract

PURPOSE:To obtain a cast-in-place pile having a great horizontal bearing capacity by a method in which reinforcing bars and tension members are erected in an excavated pit, concrete is placed into the pit and hardened, and the tension members are tensed. CONSTITUTION:Reinforcing bars 4 are erected in an excavated pit 3, and plural tension members 5, e.g., PC steel wires, etc., are erected in such a way as to fix them in adequate positions of concrete placed. Concrete 8 is then placed into the pit 3 and hardened to fix the tension members 5. The tension members 5 are tensed by a jack 10 to give them a compressive stress in order to form a prestressed concrete pile 12.

Description

【発明の詳細な説明】 本発明は場所打ち杭の水平耐力を増加するようにした場
所打ち杭の築造工法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing cast-in-place piles that increases the horizontal strength of the cast-in-place piles.

場所打ち杭の水平耐力を増大させるには、建込む鉄筋量
を増加させればよいが、配筋量によっては、鉄筋の間隔
が密になり打設コンクリートのワーカビリチーなどの施
工性と品質から杭断面を拡大するなどの問題が生じる。In order to increase the horizontal bearing capacity of cast-in-place piles, it is possible to increase the amount of reinforcing bars installed, but depending on the amount of reinforcing bars, the spacing between the reinforcing bars may become close, resulting in poor workability and quality of the cast concrete. Problems such as enlarging the cross section arise.

それだと施工費がかさむことになりむやみに建込む鉄筋
量を増加させることはできない。If that were the case, construction costs would increase, and the amount of reinforcing bars to be erected could not be increased unnecessarily.

そこで、本出願人は場所打ち杭を築造する際に、打設し
たコンクリートに圧縮応力を付与してプレストレストコ
ンクリート杭として水平耐力を増加させる場所打ち杭の
築造工法について提案した（特開昭３６−１２５５２８
号公報参照）。Therefore, the present applicant has proposed a construction method for cast-in-place piles in which compressive stress is applied to the cast concrete to increase the horizontal strength of the cast-in-place piles as prestressed concrete piles. 125528
(see publication).

この工法によれば、場所打ち杭を打設する地盤を所定の
深度掘削し、掘削した孔内に鉄筋および適数本の鋼管を
建込む。次いで、鋼管内を除いて孔内にコンクリートを
打設し、コンクリートが完全に硬化する前に鋼管を引抜
く。次いで鋼管による孔を利用してさらに支持地盤を所
定の深度掘削し、その孔内にＰＣ鋼線等の引張り部材を
挿入し支持地盤にモルタルを注入して引張り部材を定着
させる。次いでジヤツキにより引張り部材を緊張するこ
とにより杭を加工させ、杭の下方に残留している掘り屑
や沈澱物を圧密して杭の鉛直支持力を増加させる。さら
に孔内にモルタルを注入して引張り部材聚抗底部にて定
着し、ジヤツキにより引張り部材を緊張して杭に圧縮応
力を与え、孔内にモルタルを注入して孔を埋める。これ
により杭に予圧縮が与えられ、杭はプレストレストコン
クリート杭となって水平耐力が増大する。According to this construction method, the ground where cast-in-place piles are to be driven is excavated to a predetermined depth, and reinforcing bars and an appropriate number of steel pipes are installed in the excavated hole. Next, concrete is poured into the hole except for the inside of the steel pipe, and the steel pipe is pulled out before the concrete completely hardens. Next, the supporting ground is further excavated to a predetermined depth using a hole formed by the steel pipe, a tensile member such as a PC steel wire is inserted into the hole, and mortar is injected into the supporting ground to fix the tensile member. Next, the pile is processed by applying tension to the tension member using jacks, and the excavated debris and sediment remaining below the pile are consolidated to increase the vertical bearing capacity of the pile. Furthermore, mortar is injected into the hole and fixed at the bottom of the tension member, the tension member is tensed by jacking to apply compressive stress to the pile, and mortar is injected into the hole to fill the hole. This applies precompression to the pile, turning it into a prestressed concrete pile and increasing its horizontal bearing capacity.

この工法によれば、杭の水平耐力の増加をはかることが
できると共に、掘削した孔内に掘り屑や沈澱物が残留し
ていても支持地盤に定着した引張り部材を利用してジヤ
ツキにより杭を下降させることにより掘り屑や沈澱物は
圧密されて杭の鉛直支持力を増加させることができる。According to this construction method, it is possible to increase the horizontal bearing capacity of the pile, and even if there is debris or sediment left in the excavated hole, the pile can be tightened by jacking using tension members fixed to the supporting ground. By lowering, the excavated debris and sediments are consolidated and the vertical bearing capacity of the pile can be increased.

しかしこの工法による場合は、鋼管の建込み、鋼管によ
る孔を利用しての支持地盤の掘削等の工事を必要とし、
その分工費がかさむという問題点がある。また例えば７
０Ｉｌｌ近い長尺な杭の全長にわたり均一に必要とＪる
予圧縮を与えることはかなり困難である。However, this construction method requires construction work such as erecting steel pipes and excavating supporting ground using holes made by steel pipes.
There is a problem in that the construction cost increases accordingly. For example, 7
It is quite difficult to uniformly apply the necessary precompression over the entire length of a long pile close to 0Ill.

ところで、地震により水平応力を生じるのは通常地表下
１０１１１程度であり、その応力は地表に近いほど大き
い。また場所打ち杭を築造するに際して掘削した孔底に
残留する掘り屑や沈澱物をコンクリートの打設に先立ち
充分除去しておけば、それ等の残留物による杭の鉛直支
持力の低下はきたさない。By the way, horizontal stress is usually generated by an earthquake about 10111 below the earth's surface, and the stress is greater as it is closer to the earth's surface. In addition, if the debris and sediment remaining at the bottom of the excavated hole when constructing cast-in-place piles are sufficiently removed prior to concrete placement, the vertical bearing capacity of the pile will not be reduced due to such residue. .

本発明者等はこれ等の事故に基づき梗々研究、実験の結
果、引張り部材を杭の底部に定着するに限らず杭の比較
的上部に定着させて、その引張り部材により杭の比較的
−Ｌ部だけに圧縮応力を与えるＪ：うにしても杭に必要
と覆る水平耐力が充分得られることを見出した。As a result of extensive research and experiments based on these accidents, the inventors of the present invention have found that the tension member is not only fixed at the bottom of the pile, but also fixed at the relatively upper part of the pile, and the tension member is used to lower the relative height of the pile. It has been found that even if compressive stress is applied only to the L portion, the required horizontal strength of the pile can be obtained.

本発明によれば、場所打ち杭を打設する地盤を所定の深
度掘削し、掘削した孔内に鉄筋を建込むと其に、打設し
たコンクリートの適所に定着するようにした複数本の引
張り部材を建込み、鉄筋および引張り部材を建込んだ孔
内にコンクリートを打設し、コンクリ−１・が硬化した
後に引張り部材を緊張して打設したコンクリート杭に予
圧縮を付与する場所打ち杭の築造工法が提供される。According to the present invention, when the ground on which cast-in-place piles are to be driven is excavated to a predetermined depth and reinforcing bars are erected in the excavated holes, multiple tensile bars are fixed at appropriate locations in the cast concrete. A cast-in-place pile that applies precompression to a concrete pile in which concrete is poured into a hole in which members have been erected, reinforcing bars and tension members have been placed, and the tension members are placed under tension after the concrete has hardened. construction methods are provided.

場所打ちにより打設する杭長は、その上に構築される構
造物の種類、地盤等にもよるが杭長が７０Ｉｌ１以上に
なることがあり、かかる場合には引張り部材は杭の途中
、例えば地震による水平応力を受けやづい杭先端から１
０１１の所に引張り部材を定着するようにする。これに
より引張り部材を定着した個所より上方にある核部分に
は予圧縮が与えられプレストレストコンクリート杭とな
って水平耐力を増加する。The length of piles driven in place depends on the type of structure to be built on the pile, the ground, etc., but the pile length may be 70Il1 or more. In such cases, the tension member is placed in the middle of the pile, 1 from the tip of the pile, which is susceptible to horizontal stress due to earthquakes
The tension member is fixed at 011. As a result, precompression is applied to the core portion above the location where the tension member is fixed, forming a prestressed concrete pile and increasing the horizontal bearing capacity.

このよ〉・に地震により水平応力を受けやずい杭の上方
部分だけに圧縮応力を与えるものであるで、必要とプる
核部分に均一な予圧縮を比較的容易に与えることができ
る。In this way, compressive stress is applied only to the upper part of the pile, which is susceptible to horizontal stress due to earthquakes, and uniform precompression can be applied relatively easily to the required core part.

以下、図面を参照して本発明の工法を実施した実施例に
つき説明する。EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the Example which implemented the construction method of this invention is demonstrated.

場所打ち杭を打設する地盤１を掘削機２により従来の態
様にしたがい所定の深度掘削する（第１図）。掘削完了
（第２図）。Ground 1 on which cast-in-place piles are to be driven is excavated to a predetermined depth using an excavator 2 in accordance with a conventional manner (FIG. 1). Excavation completed (Figure 2).

掘削した孔３内に鉄筋４を建込むと共に、打設置ノだコ
ンクリートの適所に定着するようした複数本の引張り部
材５を建込む（第３図）、引張り部材５としては例えば
ＰＣｍｌを用いる。また定着の仕方の態様として（よ定
着させる上端部以外の部分をポリエチレン６で被覆し、
下端部５ａを周面摩擦により定着させる（第７図）が、
下端にドーナツ形のシュー７を取付ける（第８図、第９
図）。Reinforcing bars 4 are installed in the excavated hole 3, and a plurality of tension members 5 are installed so as to be fixed at appropriate positions in the poured concrete (FIG. 3). The tension members 5 are made of, for example, PCml. In addition, as an aspect of the fixing method (the part other than the upper end to be fixed is covered with polyethylene 6,
The lower end portion 5a is fixed by circumferential friction (Fig. 7).
Attach the donut-shaped shoe 7 to the lower end (Figs. 8 and 9).
figure).

孔３内にコンクリート８を打ＩＪＩスる（第４図）。Pour concrete 8 into hole 3 (Fig. 4).

打設したコンクリ−１・が硬化して引張り部材５が定着
９すれば、ジヤツキ１ｏにより引張り部材５を緊張して
杭１１に圧縮応力を与え（第５図）、プレストレストコ
ンクリート杭１２とする（第６図）。When the poured concrete 1 is hardened and the tension member 5 is fixed 9, the tension member 5 is tensed by the jack 1o to apply compressive stress to the pile 11 (Fig. 5), forming a prestressed concrete pile 12 ( Figure 6).

以上説明したように本発明の場所打ち杭の築造工法は、
プレストレストコンクリ−１〜杭となして杭の水平耐力
を増加させる必要な核部分だ【プに予圧縮を与えるもの
であるので、きわめて長尺な杭の場合にもその全長を圧
縮する従来工法に比べて施工的にもコスト的にも非常に
有利な工法であり、また予圧縮も必要な核部分に均一に
付与されて従来の工法による場合に比べて実質上より水
平耐力の大きい場所打ち杭を得ることができるものであ
る。As explained above, the method for constructing cast-in-place piles of the present invention is as follows:
Prestressed Concrete - 1 - It is a necessary core part that increases the horizontal bearing capacity of piles. This construction method is extremely advantageous in terms of construction and cost, and pre-compression is evenly applied to the core area where it is required, resulting in cast-in-place piles with substantially higher horizontal bearing capacity than conventional construction methods. This is something that can be obtained.

【図面の簡単な説明】[Brief explanation of drawings]

第１図、第２図、第３図、第４図、第５図および第６図
は本発明に係る場所打ち杭の築造工法を実施した工程図
である。第７図、第８図および第９図は引張り部材の定
着の態様を示づ正面図および平面図である。 １・・・地盤　２・・・掘削１１１３・・・孔　４・・
・鉄筋　５・・・引張り部材６・・・ボリエブレン被覆
　７・・・シュー８・・・コンクリート　９・・・定着
部１０・・・ジヤツキ　１１・・・杭　１２・・・プレ
ストレス］・コンクリート杭 第７ＦｌFIGS. 1, 2, 3, 4, 5, and 6 are process charts for carrying out the method for constructing cast-in-place piles according to the present invention. FIGS. 7, 8, and 9 are front and plan views showing the manner in which the tension member is fixed. 1... Ground 2... Excavation 1113... Hole 4...
・Reinforcement bar 5... Tension member 6... Bolibrane coating 7... Shoe 8... Concrete 9... Anchoring part 10... Jacket 11... Pile 12... Prestress] - Concrete pile 7th Fl

Claims (1)

【特許請求の範囲】[Claims] 場所打ち杭を打設する地盤を所定の深度掘削し、掘削し
た孔内に鉄筋を建込むと共に、打設したコンクリートの
適所に定着するようにした複数本の引張り部材を建込み
、鉄筋および引張り部材を建込んだ孔内にコンクリート
を打設し、コンクリートが硬化した後に引張り部材を緊
張して打設したコンクリート杭に予圧縮を付与すること
を特徴とする場所打ち杭の築造工法。The ground where the cast-in-place piles are to be driven is excavated to a specified depth, and reinforcing bars are erected in the excavated holes, and multiple tension members are erected to anchor in the appropriate locations on the concrete that has been placed. A construction method for cast-in-place piles, which is characterized in that concrete is poured into a hole in which members have been erected, and after the concrete has hardened, tension members are tensioned to impart precompression to the cast concrete pile.