JP2000045295A - Existing pile mixed type pile foundation structure and construction method - Google Patents

Existing pile mixed type pile foundation structure and construction method

Info

Publication number
JP2000045295A
JP2000045295A JP10216912A JP21691298A JP2000045295A JP 2000045295 A JP2000045295 A JP 2000045295A JP 10216912 A JP10216912 A JP 10216912A JP 21691298 A JP21691298 A JP 21691298A JP 2000045295 A JP2000045295 A JP 2000045295A
Authority
JP
Japan
Prior art keywords
pile
existing
foundation
existing pile
new
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP10216912A
Other languages
Japanese (ja)
Inventor
Eiji Wakita
英治 脇田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shimizu Construction Co Ltd
Shimizu Corp
Original Assignee
Shimizu Construction Co Ltd
Shimizu Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shimizu Construction Co Ltd, Shimizu Corp filed Critical Shimizu Construction Co Ltd
Priority to JP10216912A priority Critical patent/JP2000045295A/en
Publication of JP2000045295A publication Critical patent/JP2000045295A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To provide existing pile mixed type pile foundation structure and executing method improved so as to be capable of restraining stress intensity of an existing pile to be reused at lower than an allowable value on a pile foundation of a renewing building constituted by mixing the existing pile and a new pile. SOLUTION: Existing pile mixed type pile foundation structure is constituted by mixing an existing pile 1 to be reused for a foundation plate 2 and a new pile, and an elastic plastic body material 6 is fundamentally interposed between the foundation plate 2 and an upper end of the existing pile 1. Materially, a cavity 8 is formed between the foundation plate 2 and the upper end of the existing pile 1 by providing a bottomed hole 7 or a through hole with a cover on the foundation plate 2 and fitting the existing pile 1 in it. Additionally, a construction method of an existing pile mixed type pile foundation is to arrange the existing pile 1 and the new pile by interposing the elastic plastic body material 6 between the foundation plate 2 and an existing pile upper end 4, constitute the pile foundation so as to hold the specified cavity 8 between the foundation plate 2 and the existing pile upper end 4 after constructing an upper part structure and seal the cavity 8 with a nonshrink material after constructing the upper part structure.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、更新建築物の杭基
礎に関し、特に、既設杭と新設杭とを混在させて構成す
る更新建築物の杭基礎において、既設杭を有効に活用で
きるように改良した既設杭混在型杭基礎構造と施工方法
に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile foundation for a renovated building, and more particularly to a pile foundation for a renewed building constructed by mixing existing piles and new piles. It relates to an improved pile foundation structure with existing piles and a construction method.

【0002】[0002]

【従来の技術】近年、地球環境への負荷軽減の必要性と
建造物に対する学会、行政面からの対応の変更等から建
築物の長寿命化に対するニーズが顕在化してきている。
特に、既存の建築物を壊して同じ場所に建築物を再構築
する場合には、既存の杭基礎を廃棄せずに次に建設され
る建築物の基礎として利用する機会が増加する傾向にあ
る。このような場合には、更新建物の荷重の方が大きい
場合が多く、更新後の杭基礎が以前よりも強度的に高い
性能を要求されることが一般的であり、又、既設構造物
の杭基礎は既に数十年間使用していることから、強度を
低減して設計する必要がある。従って、既設杭だけで更
新後の建物荷重を支持することは無理である。そこで、
新たな杭を増し打ちして、既設杭と新設杭とを混在させ
て異種基礎とせざるを得ないのが現状である。
2. Description of the Related Art In recent years, the need to extend the life of buildings has become apparent due to the necessity of reducing the burden on the global environment and changes in academic and administrative responses to buildings.
In particular, when destroying an existing building and rebuilding the building in the same place, there is a tendency that the opportunity to use the existing pile foundation as the foundation of the next building without discarding it increases . In such a case, the load of the renewed building is often larger, and the pile foundation after renewal is generally required to have higher strength than before. Since the pile foundation has been used for several decades, it is necessary to design it with reduced strength. Therefore, it is impossible to support the updated building load only with the existing piles. Therefore,
At present, it is necessary to increase the number of new piles and mix existing piles and new piles to form different foundations.

【0003】既設杭と新設杭を混在させた既設杭混在型
杭基礎構造の一般概念は、図6に示す通りである。即
ち、旧建物15が地盤16に埋設された既設杭17によ
って支持されていたものを、旧建物15を解体して荷重
の大きい更新建物18を構築する場合に、上述した事情
等から既設杭15の保持している耐力をできるだけ有効
に生かしながら、新設の杭19と補完し合うように更新
建物の杭基礎を構築している。
The general concept of an existing pile mixed pile foundation structure in which existing piles and new piles are mixed is as shown in FIG. That is, when the old building 15 is supported by the existing piles 17 buried in the ground 16 and the old building 15 is dismantled to construct a renewed building 18 having a large load, the existing piles 15 are considered from the above-described circumstances and the like. The pile foundation of the renewal building is constructed so as to complement the newly-installed piles 19 while making the best use of the strength held by the piles.

【0004】ところで、この場合の載荷重と杭の沈下量
の関係を検討してみると、図7の応力履歴図に見られる
ような状態が普通である。これらの要因としては、既設
杭は過去に載荷重を受けているために、更新構造物の荷
重が載荷される時には再載荷に相当することから、荷重
が大きくても載荷重の大きさの割には沈下量が少なく現
れて、沈下量勾配が緩やかになっている。これに対し
て、新設杭は更新構造物の荷重が処女荷重であるため
に、比較的大きな沈下量を示して沈下量勾配は急激にな
っている。
By examining the relationship between the applied load and the amount of settlement of the pile in this case, a state as shown in a stress history diagram of FIG. 7 is common. One of these factors is that the existing piles received a load in the past, and when the load of the renewal structure is loaded, it corresponds to reloading. Shows a small amount of settlement, and the slope of the settlement amount is gentle. On the other hand, since the load of the renewal structure is a virgin load, the new pile shows a relatively large settlement amount and the settlement amount gradient is steep.

【0005】又、各杭の杭種の違いによっても、この傾
向が助長されている。新設杭は、既設杭のある隙間に施
工することになるので、地盤の締め固めが強くなってい
て杭の打ち込みが困難である。このため、新設杭は施工
の比較的容易な中堀り杭構法を採用するケースが多くな
り、結果的に沈下特性の相違として現れているからであ
る。
[0005] This tendency is further promoted by the difference in the pile type of each pile. New piles will be installed in the gaps between the existing piles, so the compaction of the ground will be strong and it will be difficult to drive the piles. For this reason, newly-installed piles often use the middle-boring pile construction method, which is relatively easy to construct, resulting in a difference in settlement characteristics.

【0006】従って、既設杭と新設杭とを混在させて杭
基礎を構成すると、同じ載荷荷重に対しても、既設杭の
沈下が新設杭のそれに対して相対的に少ないために、既
設杭の方に荷重が強く集中する結果、既設杭が過剰応力
の状態に至る。以上のように、既設杭と新設杭を単純に
混在させる設計では、杭全体が均等に構造物を支持して
既設杭を有効に再利用できるように処置することができ
ないので、既設杭の応力度を許容値以下に抑える必要が
ある。
Therefore, when a pile foundation is formed by mixing an existing pile and a new pile, the settlement of the existing pile is relatively small with respect to that of the new pile even for the same load. As a result, the existing pile is over-stressed. As described above, in the design where existing piles and new piles are simply mixed, it is not possible to treat the entire pile evenly to support the structure uniformly and to reuse the existing piles effectively. The degree must be kept below the allowable value.

【0007】[0007]

【発明が解決しようとする課題】本発明は、既設杭と新
設杭とを混在させて構成する更新建築物の杭基礎におい
て、再利用する既設杭の応力度を許容値以下に抑えるよ
うに改良した既設杭混在型杭基礎構造と施工方法を提供
するものである。
SUMMARY OF THE INVENTION The present invention relates to an improved pile foundation for a rebuilt building, in which existing piles and new piles are mixed, so that the stress level of existing piles to be reused is suppressed to an allowable value or less. It is intended to provide an existing pile mixed type pile foundation structure and a construction method.

【0008】[0008]

【課題を解決するための手段】本発明による既設杭混在
型杭基礎構造は、基礎版に再利用する既設杭と新設杭と
を混在させて構成し、基礎版と既設杭上端との間に弾塑
性体状材料を介在させることを基本的にしており、具体
的には、基礎版に既設杭を嵌入させる有底孔や蓋をした
貫通孔を設けて既設杭の上端面と底部もしくは蓋との間
に空隙を形成することを特徴にしており、既設杭に許容
応力以上の荷重応力を加えないようにして、既設杭と新
設杭とを有効に活用して更新構造物を支持している。
又、本発明による既設杭混在型杭基礎の施工方法は、基
礎版と既設杭上端との間に弾塑性体状材料を介在させて
既存杭と新設杭を配置し、上部構造物の構築後に基礎版
と既設杭上端との間に所定の空隙を保持させるように杭
基礎を構成し、上部構造物を構築した後に、該空隙を無
収縮材で封鎖することを特徴としており、既設杭に許容
応力以上の荷重応力を加えずに、既設杭と新設杭とを有
効に活用した支持が可能なように施工できる。
An existing pile mixed type pile foundation structure according to the present invention is constructed by mixing existing piles to be reused for a foundation plate and new piles, and is provided between the foundation plate and the upper end of the existing pile. Basically, an elasto-plastic material is interposed.Specifically, a bottomed hole or a through hole with a lid is provided in the base plate to insert the existing pile, and the upper end surface of the existing pile and the bottom or the lid are provided. It is characterized by forming an air gap between the existing pile and the existing pile and the new pile to effectively utilize the existing pile and the new pile to support the renewal structure so as not to apply a load stress exceeding the allowable stress to the existing pile. I have.
Further, the construction method of the existing pile mixed pile foundation according to the present invention is to arrange the existing pile and the new pile by interposing an elasto-plastic material between the foundation plate and the upper end of the existing pile, and after constructing the upper structure. The pile foundation is configured to hold a predetermined gap between the foundation plate and the upper end of the existing pile, and after constructing the upper structure, the gap is sealed with a non-shrinkable material, and the existing pile is The construction can be carried out so that the existing pile and the new pile can be effectively used and supported without applying a load stress exceeding the allowable stress.

【0009】[0009]

【発明の実施の形態】図1は、本発明による既設杭混在
型杭基礎構造における既設杭の杭頭部分の断面図であ
る。図において、既設杭1は図示されていない新設杭と
共に基礎版2と一体になって杭基礎構造を構成してい
る。新設杭は、通常の構法を持って施工されているの
で、その説明は省略する。既設杭1の頭部には、複数の
中空孔3が上端面4に均一に配設してある。中空孔の底
面には鋼製の底板5が敷設されていて、後述する弾塑性
体状材料6が既設杭頭部に敷設されるのを受け支えてい
る。底板5は、弾塑性体状材料6からの荷重を既設杭全
域に均等に伝達されるように配置していることから、そ
の大きさは適宜決定されている。
FIG. 1 is a sectional view of a pile head portion of an existing pile in an existing pile mixed pile foundation structure according to the present invention. In the figure, an existing pile 1 is integrated with a foundation plate 2 together with a new pile (not shown) to constitute a pile foundation structure. Since the new pile is constructed using the normal construction method, the description is omitted. In the head of the existing pile 1, a plurality of hollow holes 3 are uniformly arranged on the upper end surface 4. A steel bottom plate 5 is laid on the bottom surface of the hollow hole, and supports the below-described elasto-plastic material 6 to be laid on the existing pile head. The size of the bottom plate 5 is appropriately determined because the bottom plate 5 is arranged so that the load from the elastic-plastic body material 6 is evenly transmitted to the entire area of the existing pile.

【0010】基礎版2から既設杭1への鉛直応力は、施
工初期の段階では直接既設杭1の頭部に伝達させず、介
在させた弾塑性体状材料6を経由して伝えられるように
構成する。このため、基礎版2の底面側には、基礎版2
の内部まで伸張した有底孔7を形成し、有底孔7には図
示のように既設杭1の頭部を嵌入して、有底孔7の底面
に弾塑性体状材料6を接触させて、既設杭1の頭部上端
面4と有底孔7の底面との間には、所定の空隙8を形成
保持させている。空隙8に通じている2本のパイプ9,
10は、無収縮グラウトの注入と空気抜き用であり、基
礎版の上の上部構造が完成して載荷荷重の状況が定着し
た段階で空隙8を封鎖するために予め設置している。
既設杭1の頭部と有底孔7との周面には、硬質ゴム製の
緩衝体11を配置しており、既設杭1と緩衝体11とが
接する間には剥離材が塗布されていて、既設杭1と基礎
版2とが鉛直方向に摺動することを可能にして、上記し
た鉛直応力伝達が円滑に行われるのを助長している。
The vertical stress from the base plate 2 to the existing pile 1 is not transmitted directly to the head of the existing pile 1 at the initial stage of construction, but is transmitted via the interposed elasto-plastic material 6. Constitute. For this reason, the base plate 2 is provided on the bottom side of the base plate 2.
Is formed, and the head of the existing pile 1 is fitted into the bottomed hole 7 as shown in the drawing to bring the elasto-plastic material 6 into contact with the bottom surface of the bottomed hole 7. A predetermined gap 8 is formed and held between the upper end surface 4 of the head of the existing pile 1 and the bottom surface of the bottomed hole 7. Two pipes 9 leading to the gap 8
Numeral 10 is for injecting non-shrinkage grout and bleeding air, and is provided in advance to close the gap 8 when the upper structure on the base plate is completed and the state of the load is fixed.
A hard rubber buffer 11 is arranged on the peripheral surface between the head of the existing pile 1 and the bottomed hole 7, and a release material is applied between the existing pile 1 and the buffer 11 while they are in contact with each other. Thus, the existing pile 1 and the base plate 2 are allowed to slide in the vertical direction, and the above-mentioned vertical stress transmission is facilitated.

【0011】次に、弾塑性体状材料を図2及び図3に基
づいて説明する。本発明で用いる弾塑性体状材料6は、
「完全弾塑性体に近い特性を備えた」弾性材を称してい
る。このような弾性体としては、極低降伏点鋼材等が該
当しているので、極低降伏点鋼材の性質を示して弾塑性
体状材料6の性質を説明する。図2は、極低降伏点鋼材
の歪ー応力度関係の特性を示している。極低降伏点鋼材
の極限応力度は、σmax =2,400〜2,600
kg/cm2程度であり、普通鋼の約半分である。そし
て、図示のように歪10%程度でこの極限応力度付近に
到達し、それ以上は歪50%付近までその値が持続する
特徴を持っている。本発明に用いる弾塑性体状材料6の
歪ー応力度関係は、図3に示すような理想的構造モデル
による「完全弾塑性体型の応力―歪関係」を指向してい
る。同応力―歪関係は、図示のようにわずかな歪で応力
度が所定値に到達しながら、それ以上に歪が増加して大
きな歪に至っても、応力度が所定値付近に留まったまま
推移する性質を示している。「完全弾塑性体に近い特性
を備えた」弾性材としては、極低降伏点鋼の他に、低降
伏点鋼や極軟鋼等も同様の特性を有している。
Next, the elasto-plastic material will be described with reference to FIGS. The elasto-plastic body material 6 used in the present invention is:
It refers to an elastic material "having characteristics close to that of a perfect elastoplastic body". As such an elastic body, an extremely low yield point steel material or the like is applicable. Therefore, the properties of the extremely low yield point steel material will be described, and the properties of the elasto-plastic material 6 will be described. FIG. 2 shows the characteristics of the strain-stress relationship of the extremely low yield point steel. The ultimate stress degree of the extremely low yield point steel material is σmax = 2,400 to 2,600
It is about kg / cm2, about half that of ordinary steel. Then, as shown in the figure, the strain reaches the vicinity of the ultimate stress at a strain of about 10%, and has a characteristic that the value is maintained up to a strain of about 50% after that. The strain-stress relationship of the elasto-plastic material 6 used in the present invention is directed to the "stress-strain relationship of a perfect elasto-plastic material type" based on an ideal structure model as shown in FIG. The stress-strain relationship shows that the stress level reaches a predetermined value with a slight strain as shown in the figure, and even if the strain increases further and reaches a large strain, the stress level remains near the predetermined value. Shows the nature of As an elastic material having "characteristics close to a perfect elasto-plastic body", in addition to the extremely low yield point steel, a low yield point steel, an extremely mild steel, and the like also have similar characteristics.

【0012】既設杭1と基礎版2とは、上述のように弾
塑性体状材料6を介在して設定されているので、上部構
造の施工時には上部構造からの鉛直応力は全て、弾塑性
体状材料6を経由して既設杭1に伝達される。弾塑性体
状材料6は、上記の特性を備えているので、伝達してい
る鉛直応力が所定応力を越えると、伝達する応力を所定
値以内に納めるように弾塑性体状材料6の長さを縮小さ
せて反応し、既設杭1には所定値以上の応力を伝達しな
い。従って、既設杭1には、上部構造物が完成した段階
までは所定の鉛直応力度より大きい応力度にならない状
態を形成することになる。
Since the existing pile 1 and the foundation plate 2 are set with the elasto-plastic material 6 interposed therebetween as described above, all vertical stresses from the upper structure during the construction of the upper structure are elasto-plastic. It is transmitted to the existing pile 1 via the material 6. Since the elasto-plastic material 6 has the above-described characteristics, when the transmitted vertical stress exceeds a predetermined stress, the length of the elasto-plastic material 6 is adjusted so that the transmitted stress falls within a predetermined value. And does not transmit a stress exceeding a predetermined value to the existing pile 1. Therefore, the existing pile 1 is formed in a state where the stress does not become larger than the predetermined vertical stress until the upper structure is completed.

【0013】図4は、本発明による既設杭混在型杭基礎
構造の載荷重と杭の沈下量の関係を示す応力履歴図であ
る。上部構造物の施工が続けられると、既設杭1は所定
の応力分のみを分担するから、上部構造物の鉛直応力度
の増加分は新設杭が負担して杭の沈下量を増やして行く
ことになる。構造物がほとんど完成し、構造物荷重がほ
ぼ完全に作用した段階で、既設杭1の空隙8に注入用の
パイプ9から無収縮グラウトを注入して既設杭1と基礎
版2とを一体化し、弾塑性体状材料6の作用を完了させ
る。これによって、構造物の竣工時点では、既設杭1に
許容可能な所定の鉛直応力を分担させ、新設杭は残りの
鉛直荷重を分担して、建物全体としては性能に応じた杭
応力分担状態を形成している。
FIG. 4 is a stress history diagram showing the relationship between the load and the settlement amount of the pile in the existing pile mixed pile foundation structure according to the present invention. If the construction of the superstructure is continued, the existing pile 1 will only share the predetermined stress, so the increase in the vertical stress of the superstructure will be borne by the new pile and the pile settlement will increase. become. When the structure is almost completed and the structure load is almost completely applied, non-shrinkage grout is injected into the gap 8 of the existing pile 1 from the injection pipe 9 to integrate the existing pile 1 and the foundation plate 2. Then, the operation of the elastic-plastic body material 6 is completed. As a result, at the time of completion of the structure, the existing pile 1 is allowed to share the allowable vertical stress, the new pile is allowed to share the remaining vertical load, and the pile stress sharing state according to the performance of the entire building is adjusted. Has formed.

【0014】以上のように、従来の工法では図7のよう
に、既設杭が小さい沈下量で大きな能力以上の荷重を分
担し、新設杭は大きな沈下量で結果的に少ない荷重分担
で済ましていたものを、本発明による既設杭混在型杭基
礎構造と施工方法によれば、図4で明らかなように、既
設杭は所定の許容応力値のままで沈下だけをさせて行
き、新設杭には単純に既設杭分を除いた残りの応力を分
担させて沈下量は既設杭と同一の値に設定できているこ
とを知ることができる。
As described above, in the conventional construction method, as shown in FIG. 7, the existing piles share a load larger than a large capacity with a small settlement amount, and the new piles have a small settlement amount and consequently a small load sharing. According to the existing pile mixed type pile foundation structure and the construction method according to the present invention, as shown in FIG. 4, the existing pile is allowed to settle only while maintaining the predetermined allowable stress value, and the new pile is moved to the new pile. Can simply share the remaining stress excluding the existing piles and know that the settlement amount can be set to the same value as the existing piles.

【0015】図5は、本発明による既設杭混在型杭基礎
構造について、他の実施の形態を示す既設杭の杭頭部分
の断面図である。本実施の形態では、既設杭1の形状は
前述の例と同様であるが、基礎版2の形状を異にしてい
る。前例では、基礎版2の底面側に基礎版2の内部まで
伸張した有底孔7を形成するために、型枠材の設定やコ
ンクリートの打設に細かい配慮が必要であるが、基礎版
2の施工を簡潔にしてコストダウンを図るのが本実施の
形態例の目的である。基礎版2には、既設杭1を挿入さ
せるために有底孔を形成せず、筒抜けの貫通孔12が設
けられており、基礎版2の貫通孔は蓋13で覆われてい
る。蓋13は、アンカーボルト14によって基礎版2と
堅固に一体化されているが、前例と同様に、既設杭1の
頭部上端面4と蓋13との間に空隙8を形成しており、
この空隙8に通じた無収縮グラウトの注入用パイプ9と
空気抜き用パイプ10を蓋13に設けている。又、既設
杭1と基礎版2の孔壁との間に緩衝材を配置することも
同様である。
FIG. 5 is a sectional view of a pile head portion of an existing pile showing another embodiment of the existing pile mixed pile foundation structure according to the present invention. In the present embodiment, the shape of the existing pile 1 is the same as that of the above-mentioned example, but the shape of the basic slab 2 is different. In the previous example, in order to form the bottomed hole 7 extending to the inside of the basic slab 2 on the bottom side of the basic stencil 2, it is necessary to pay careful attention to the setting of the form material and the casting of the concrete. The purpose of the present embodiment is to simplify the construction and reduce costs. The base plate 2 is not provided with a bottomed hole to insert the existing stake 1, but is provided with a through-hole 12 through which the cylinder passes through. The through-hole of the base plate 2 is covered with a lid 13. The lid 13 is firmly integrated with the base plate 2 by an anchor bolt 14, but as in the previous example, a gap 8 is formed between the head upper end surface 4 of the existing pile 1 and the lid 13.
A lid 9 is provided with a pipe 9 for injecting non-shrinkage grout and a pipe 10 for venting air, which are connected to the gap 8. The same applies to the arrangement of a cushioning material between the existing pile 1 and the hole wall of the base plate 2.

【0016】本発明による既設杭混在型杭基礎の施工方
法は、次のように実施される。先ず、上記各実施の形態
に従って既設杭1を基礎版2に嵌入させて杭基礎を構築
するが、この段階では既設杭1の上端に形成された空隙
8には何も注入されておらず、弾塑性体状材料6が基礎
版上の載荷荷重による鉛直荷重を既設杭に自由に伝達で
きる状態にしてある。基礎版上に、上部構造の施工が継
続されている時には上部構造からの鉛直応力は全て、弾
塑性体状材料6を経由して既設杭1に伝達される。弾塑
性体状材料6は、伝達している鉛直応力が所定値を越え
ると、その長さを縮小させて反応し、既設杭1には所定
値以上の応力を伝達しないから、既設杭1には上部構造
物が完成した段階まで所定の鉛直応力より作用しない状
態を維持する。
The method for constructing an existing pile mixed pile foundation according to the present invention is carried out as follows. First, according to the above embodiments, the existing pile 1 is inserted into the foundation slab 2 to construct a pile foundation. At this stage, nothing is injected into the gap 8 formed at the upper end of the existing pile 1, The elasto-plastic material 6 can freely transmit the vertical load caused by the load on the base plate to the existing pile. When the construction of the superstructure is continued on the base slab, all vertical stresses from the superstructure are transmitted to the existing pile 1 via the elasto-plastic material 6. When the transmitted vertical stress exceeds a predetermined value, the elasto-plastic material 6 reacts by reducing its length and does not transmit a stress exceeding a predetermined value to the existing pile 1. Maintains a state in which the upper structure does not act by a predetermined vertical stress until it is completed.

【0017】上部構造物の完成までは、既設杭1は所定
の応力分のみを分担して沈下量を増やし続けるから、上
部構造物の鉛直応力度の増加分は新設杭が負担して杭の
沈下量を増やして行くことになる。上部構造物が完成に
近くなって構造物荷重がほぼ完全に作用した段階になる
と、既設杭1の空隙8に注入用のパイプ9から無収縮グ
ラウトを注入し既設杭1と基礎版2とを一体化して弾塑
性体状材料6の作用を完了させる。これによって、施工
作業を完了するが、この状態では、既設杭1に許容可能
な鉛直応力を分担させて新設杭が残りの鉛直荷重を分担
しているから、建物全体としては性能に応じた杭応力分
担状態を形成して合理的な建物更新が達成されている。
Until the completion of the upper structure, the existing pile 1 continues to increase the amount of settlement by sharing only a predetermined stress, so that the increase in the vertical stress of the upper structure is borne by the new pile and The amount of settlement will increase. When the upper structure is almost completed and the structure load is almost completely applied, the non-shrinkage grout is injected from the injection pipe 9 into the gap 8 of the existing pile 1 and the existing pile 1 and the foundation plate 2 are connected. The operation of the elasto-plastic body material 6 is completed by integration. By this, the construction work is completed. In this state, the existing piles 1 share the allowable vertical stress and the new piles share the remaining vertical load. A rational building renewal is achieved by forming a stress sharing state.

【0018】[0018]

【実施例】弾塑性体状材料として、極低降伏点鋼を採用
した場合の形状寸法について、実施例を以下に示す。直
径1mの杭の常時許容支持力は、300tであるから、
既設杭に同様の許容支持力を所定値として設定する場合
について検討する。一般に、300tの荷重が作用した
とき、杭の沈下量は直径の1%程度といわれることか
ら、杭の直径が1mであると沈下量は最大1cm程度と
推定される。図2に示した極低降伏点鋼の特性から、1
0%の歪時に所定値としたσmax=2,400kg/
cm2 に達して、1cmの沈下が生じるようにするた
めには、弾塑性体状材料を、長さ10cm、断面5.6
cm×5.6cmにして、これを4本用意する必要があ
る。即ち、 2,400kg/cm2 ×(5.6cm×5.6c
m)×4≒300t として、300tの荷重を受けて既設杭には2,400
kg/cm2 の許容範囲内の応力を伝達しながら、1
cmの沈下に抑えられるからである。
EXAMPLES Examples of the shape and dimensions when an extremely low yield point steel is used as the elasto-plastic material will be described below. Since the always allowable bearing capacity of a 1m diameter pile is 300t,
Consider the case where the same allowable bearing capacity is set as a predetermined value for the existing pile. Generally, when a load of 300 t is applied, the settlement amount of the pile is said to be about 1% of the diameter. Therefore, when the diameter of the pile is 1 m, the settlement amount is estimated to be about 1 cm at the maximum. From the characteristics of the extremely low yield point steel shown in FIG.
Σmax = 2,400 kg /, which is a predetermined value at the time of strain of 0%
In order to reach 1 cm 2 and to cause a 1 cm subsidence, the elasto-plastic body material should be 10 cm long and 5.6 in section.
cm × 5.6 cm, and it is necessary to prepare four of them. That is, 2,400 kg / cm 2 × (5.6 cm × 5.6c
m) × 4 ≒ 300t, the existing pile is loaded with 2,400
While transmitting stress within the allowable range of kg / cm2, 1
It is because it can be suppressed to the subsidence of cm.

【0019】以上詳細に説明したように、本発明による
既設杭混在型杭基礎構造は、既存の建物を撤去した跡地
に更新建物を構築する場合や土木構造物を更新する場合
に、既設杭をその履歴状態に沿った有効な活用形態で処
置し、新設杭との補完関係において統合的に最善の杭基
礎構造を提供しているものであり、説明のために紹介し
た実施の形態及び実施例は、あくまでも例示的な内容で
あって、本発明は何らこれに限定されるものでなく、発
明の主旨を逸脱しない範囲において他の形態についても
本発明に含まれるものである。
As described above in detail, the existing pile-mixed pile foundation structure according to the present invention can be used to replace an existing pile with a new one at the site where an existing building has been removed or when renewing a civil engineering structure. It is an effective utilization form according to the history state, and provides the best pile foundation structure in an integrated manner in relation to the new pile, and the embodiment and example introduced for explanation. Is merely an example, and the present invention is not limited to this, and other forms are included in the present invention without departing from the gist of the invention.

【0020】[0020]

【発明の効果】本発明による既設杭混在型杭基礎構造
は、基礎版に再利用する既設杭と新設杭とを混在させて
構成し、基礎版と既設杭上端との間に弾塑性体状材料を
介在させることを特徴としているので、既設杭には許容
応力以上の応力度を生じさせないように新設杭の設計を
し、既設杭と新設杭とをそれぞれの特性に応じた応力分
担をするように有効に配置して更新構造物を支持できる
効果を奏している。
According to the present invention, an existing pile mixed type pile foundation structure according to the present invention is constructed by mixing existing piles to be reused for a foundation plate and new piles, and an elasto-plastic body is formed between the foundation plate and the existing pile upper end. Since the material is interposed, the new pile is designed so that the existing pile does not exceed the allowable stress, and the existing pile and the new pile are assigned stress according to their characteristics. In this way, the renewal structure can be effectively arranged and supported.

【0021】又、本発明による既設杭混在型杭基礎の施
工方法は、基礎版と既設杭上端との間に弾塑性体状材料
を介在させて既存杭と新設杭を配置し、上部構造物の構
築後に基礎版と既設杭上端との間に所定の空隙を保持さ
せるように杭基礎を構成し、上部構造物を構築した後
に、空隙を無収縮材で封鎖することを特徴としているの
で、既設杭には許容応力度以上の応力度を生じさせずに
上部構造物の構築を推進し、上部構造物の完成後は既設
杭と新設杭とが同一の沈下量の下で各杭の特性に応じた
応力の持分を分担し合った支持が可能なように施工でき
る効果を発揮するものである。
Further, the method for constructing an existing pile mixed type pile foundation according to the present invention is a method of arranging an existing pile and a new pile by interposing an elasto-plastic material between a foundation plate and an upper end of the existing pile. Since the pile foundation is configured to hold a predetermined gap between the foundation plate and the upper end of the existing pile after construction, and after constructing the upper structure, the gap is sealed with non-shrinkage material, The construction of the superstructure is promoted without causing the existing piles to exceed the allowable stress level.After the completion of the superstructure, the existing piles and the new piles have the same settlement amount and the characteristics of each pile Therefore, it is possible to carry out the construction in such a manner that the support sharing the share of the stress according to the above is possible.

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

【図1】本発明による既設杭混在型杭基礎構造における
既設杭の杭頭部分の断面図
FIG. 1 is a sectional view of a pile head portion of an existing pile in an existing pile mixed pile foundation structure according to the present invention.

【図2】本発明に用いる極低降伏点鋼の歪ー応力度関係
FIG. 2 is a diagram showing the relationship between strain and stress of the ultra-low yield point steel used in the present invention.

【図3】本発明に用いる弾塑性体状材料の歪ー応力度関
係図
FIG. 3 is a diagram showing the relationship between strain and stress of the elastoplastic material used in the present invention.

【図4】既設杭混在型杭基礎構造の載荷重―杭沈下量関
係図
Fig. 4 Relationship between loading and pile settlement of existing pile mixed pile foundation structure

【図5】本発明による他の既設杭混在型杭基礎構造にお
ける既設杭の杭頭部分の断面
FIG. 5 is a cross section of a pile head portion of an existing pile in another existing pile mixed type pile foundation structure according to the present invention.

【図6】従来の既設杭混在型杭基礎構造の概念図FIG. 6 is a conceptual view of a conventional existing pile-mixed pile foundation structure.

【図7】従来の既設杭混在型杭基礎構造の載荷重―杭沈
下量関係図
[Fig. 7] Relationship between loading capacity and pile settlement amount of conventional existing pile mixed pile foundation structure

【符号の説明】[Explanation of symbols]

1 既設杭 12 貫通
孔 2 基礎版 13 蓋 3 中空孔 14 アン
カーボルト 4 上端面 15 旧建
物 5 底板 16地盤 6 弾塑性体状材料 17 既設
杭 7 有底孔 18 更新
建物 8 空隙 19 新設
杭 9 無収縮グラウトの注入用パイプ 10 空気抜用パイプ 11 緩衝材
DESCRIPTION OF SYMBOLS 1 Existing pile 12 Through hole 2 Base plate 13 Lid 3 Hollow hole 14 Anchor bolt 4 Upper end surface 15 Old building 5 Bottom plate 16 Ground 6 Elasto-plastic material 17 Existing pile 7 Bottom hole 18 Renewal building 8 Void 19 New pile 9 None Pipe for injecting shrunk grout 10 Pipe for venting air 11 Buffer material

Claims (5)

【特許請求の範囲】[Claims] 【請求項1】 基礎版に再利用する既設杭と新設杭とを
混在させて構成する杭基礎構造において、基礎版と既設
杭上端との間に弾塑性体状材料を介在させることを特徴
とする既設杭混在型杭基礎構造。
1. A pile foundation structure in which an existing pile and a new pile reused for a foundation slab are mixed, wherein an elastic-plastic material is interposed between the foundation slab and the upper end of the existing pile. Existing pile mixed type pile foundation structure.
【請求項2】 基礎版に、既設杭を嵌入させる有底孔を
設けることを特徴とする請求項1に記載の杭基礎。
2. The pile foundation according to claim 1, wherein the foundation plate is provided with a bottomed hole into which the existing pile is fitted.
【請求項3】 基礎版に、上端を基礎版に接合の蓋で閉
塞した既設杭の貫通孔を設けることを特徴とする請求項
1に記載の杭基礎。
3. The pile foundation according to claim 1, wherein the foundation slab is provided with a through hole of an existing pile, the upper end of which is closed by a lid joined to the foundation slab.
【請求項4】 基礎版と既設杭の周壁との間に緩衝材を
配置することを特徴とする請求項1〜3のいずれかに記
載の既設杭混在型杭基礎構造。
4. The existing pile mixed pile foundation structure according to claim 1, wherein a cushioning material is arranged between the foundation slab and the peripheral wall of the existing pile.
【請求項5】 基礎版と既設杭上端との間に弾塑性体状
材料を介在させて既存杭と新設杭を配置し、上部構造物
の構築後に基礎版と既設杭上端との間に所定の空隙を保
持させるように杭基礎を構成し、上部構造物を構築した
後に、該空隙を無収縮材で封鎖することを特徴とする請
求項1〜4のいずれかに記載の既設杭混在型杭基礎の施
工方法。
5. An existing pile and a new pile are arranged with an elasto-plastic material interposed between the foundation slab and the upper end of the existing pile, and a predetermined space is provided between the base slab and the upper end of the existing pile after the upper structure is constructed. A pile foundation is constructed so as to hold a void, and after the upper structure is constructed, the void is closed with a non-shrinkable material, and the existing pile mixed type according to any one of claims 1 to 4, Construction method of pile foundation.
JP10216912A 1998-07-31 1998-07-31 Existing pile mixed type pile foundation structure and construction method Pending JP2000045295A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP10216912A JP2000045295A (en) 1998-07-31 1998-07-31 Existing pile mixed type pile foundation structure and construction method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP10216912A JP2000045295A (en) 1998-07-31 1998-07-31 Existing pile mixed type pile foundation structure and construction method

Publications (1)

Publication Number Publication Date
JP2000045295A true JP2000045295A (en) 2000-02-15

Family

ID=16695876

Family Applications (1)

Application Number Title Priority Date Filing Date
JP10216912A Pending JP2000045295A (en) 1998-07-31 1998-07-31 Existing pile mixed type pile foundation structure and construction method

Country Status (1)

Country Link
JP (1) JP2000045295A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013249709A (en) * 2012-06-04 2013-12-12 Taisei Corp Pile reinforcing structure for existing building, and constructing method thereof
CN105569098A (en) * 2016-01-12 2016-05-11 铁道第三勘察设计院集团有限公司 Determination method of pile length of free section of slope pile foundation
CN109162289A (en) * 2018-10-30 2019-01-08 江西博慧工程技术服务有限公司 The prefabricated carrying pier structure of one kind and its construction method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013249709A (en) * 2012-06-04 2013-12-12 Taisei Corp Pile reinforcing structure for existing building, and constructing method thereof
CN105569098A (en) * 2016-01-12 2016-05-11 铁道第三勘察设计院集团有限公司 Determination method of pile length of free section of slope pile foundation
CN105569098B (en) * 2016-01-12 2017-05-24 铁道第三勘察设计院集团有限公司 Determination method of pile length of free section of slope pile foundation
CN109162289A (en) * 2018-10-30 2019-01-08 江西博慧工程技术服务有限公司 The prefabricated carrying pier structure of one kind and its construction method

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