JPS6278322A - Earthquake-proofing structure of pile foundation - Google Patents
Earthquake-proofing structure of pile foundationInfo
- Publication number
- JPS6278322A JPS6278322A JP21521785A JP21521785A JPS6278322A JP S6278322 A JPS6278322 A JP S6278322A JP 21521785 A JP21521785 A JP 21521785A JP 21521785 A JP21521785 A JP 21521785A JP S6278322 A JPS6278322 A JP S6278322A
- Authority
- JP
- Japan
- Prior art keywords
- ground
- footing
- pile foundation
- piles
- earthquake
- 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
Links
Landscapes
- Foundations (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は杭基礎の耐震性能を長期にわたって保持するた
めの基礎構造、特に地盤の圧密沈下によって基礎スラブ
またはフーチング底面と地盤との間に生ずる空隙により
、杭基礎の耐震性能が低下することを防止するための杭
基礎構造に関するものである。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a foundation structure for maintaining the seismic performance of a pile foundation over a long period of time, and in particular to a foundation structure for maintaining the seismic performance of a pile foundation over a long period of time. The present invention relates to a pile foundation structure for preventing the seismic performance of the pile foundation from deteriorating due to voids.
軟弱地盤など直接地盤に支持力を回持できにくい地盤に
構造物を構築する場合には、杭基礎構造を用いることが
古くから知られている。またこの種の地盤では、圧密沈
下を生ずることがよく知られており、そのためこのよう
な現象に伴って杭に作用するネガティブフリクションな
どの問題に対しては、従来より種々の対策が提唱され、
実際に実施されている。It has long been known to use pile foundation structures when building structures on soft ground or other ground where it is difficult to directly transfer bearing capacity to the ground. In addition, it is well known that consolidation settlement occurs in this type of ground, and for this reason, various countermeasures have been proposed in the past to deal with problems such as negative friction that acts on piles due to this phenomenon.
It is actually being implemented.
しかしながら杭基礎構造における地盤の圧密沈下に伴っ
て生ずる問題点としては、前記のような杭に作用するネ
ガティブフリクションなどの現象と別に、更にもう一つ
の現象、即ら地盤の圧密沈下により基礎スラブまたはフ
ーチングの底面と地盤との間に生ずる空隙による耐震性
能の著しい低下現象が重大な問題となる。However, in addition to the above-mentioned phenomenon such as negative friction that acts on the piles, there is another problem that arises due to consolidation settlement of the ground in pile foundation structures. A serious problem is that the seismic performance deteriorates significantly due to the voids that form between the bottom of the footing and the ground.
従来におけるこの種の問題点に対する考え方としては、
一応、設計の段階で常時の荷重（自重十活荷重）に対し
ては杭の支持力でもたせているために、多少フーチング
底面の地盤が沈下したとしても、それが設計時に想定し
た範囲位のものであれば、支持力には問題を生ずること
はないとされていた。The conventional way of thinking about this type of problem is as follows:
At the design stage, the bearing capacity of the piles is used to support the constant load (dead weight and live load), so even if the ground at the bottom of the footing sinks a little, it will only be within the range assumed at the time of design. It was believed that there would be no problem with the supporting capacity.
しかしながら、このような考え方は、あくまで静的な面
からのみの評価ではあっても、地震時あるいは連続的機
械振動のような動的な面を考慮に入れた評価とは言い難
い。However, although this kind of thinking is only an evaluation from a static aspect, it cannot be said to be an evaluation that takes into account dynamic aspects such as earthquakes or continuous mechanical vibrations.
このような動的な面を考慮に入れた場合、フーチング底
面と地盤との間に空隙が生ずると、本来杭基礎が初期に
保持していた減衰効果（振動を抑制する能力）が低下す
るために増幅倍率が増大する結果となり、これが耐震性
能の著しい低下を引き起すこととなってしまう。Taking such dynamic aspects into account, if a gap is created between the bottom of the footing and the ground, the damping effect (ability to suppress vibrations) that the pile foundation originally had will decrease. This results in an increase in the amplification factor, which causes a significant decline in seismic performance.
本発明は上記のような地盤沈下によりフーチング底面と
地盤との間に空隙が生ずるために、杭基礎の耐震性能が
低下することの問題点を解消するために、杭により支持
されるフーチング底面から抗相互間の地盤中に向けて、
予じめ所定の長さをもつ多数本の突起物を突設しておき
、地盤の圧密沈下によって生ずるフーチング底面と地盤
との接触面積の減少を補うことを特徴としたものである
。The present invention aims to solve the problem that the seismic performance of pile foundations deteriorates due to the formation of voids between the footing bottom and the ground due to ground subsidence as described above. Towards the ground between the two sides,
The feature is that a large number of protrusions of a predetermined length are provided in advance to compensate for the reduction in the contact area between the bottom of the footing and the ground that occurs due to consolidation subsidence of the ground.
フーチング底面から地盤中に向は予じめ多数本の突起物
が突設されていると、地盤の圧密沈下によってフーチン
グ底面と地盤とに空隙が生じても、依然として地盤中に
突出している突起物の表面積の分だけ空隙率の増大を防
ぎ、突起物と地盤との接触面積の減少を補うこととなる
。If a large number of protrusions are pre-installed protruding from the bottom of the footing into the ground, even if a gap is created between the bottom of the footing and the ground due to consolidation settlement of the ground, the protrusions will still protrude into the ground. This prevents an increase in porosity by the amount of surface area and compensates for the decrease in the contact area between the protrusion and the ground.
次に本発明に係る構造を図面により説明すると、第１図
に示すように、支持層７に達する杭２によって地表面６
の下方の地盤８上に支持されるフーチング１内の底面か
ら、捨コンクリート４及び割栗石５を貫通して、杭２の
相互間の地盤８内に向け、予じめ所定の長さをもった多
数本の突起物３を一体的に突設して貫入させる。これら
の突起物３は、杭２と同様にコンクリートもしくは表面
に防蝕処理を施した鋼管、鋼矢板などフーチング１と実
質的な一体性をもつように突設される剛性のものであれ
ばよい。またこれらの突起物３の長さは、設計に際して
構築する構造物の耐用年数を考慮し、その耐用期間中に
おける地盤の圧密沈下量を予じめ予測し、その沈下量に
見合った突起長として設計される。なおこれらの突起物
３は、第３図に示すように地盤沈下によって生ずるフー
チング底面と地盤８との間の空隙９に伴う接触面積の減
少をできるだけ少なくするため、夫々所定の太さをもっ
て広い範囲の面積に分布されるように設けることが望ま
しい。Next, the structure according to the present invention will be explained with reference to the drawings. As shown in FIG.
From the bottom of the footing 1 supported on the ground 8 below, pass through the concrete 4 and the split stones 5 and into the ground 8 between the piles 2 with a predetermined length. A large number of protrusions 3 are integrally protruded and penetrated. Similar to the piles 2, these protrusions 3 may be made of concrete, steel pipes with corrosion-resistant surfaces, steel sheet piles, or other rigid materials that protrude substantially integrally with the footing 1. In addition, the length of these protrusions 3 is determined by considering the service life of the structure to be constructed at the time of design, predicting the amount of consolidation settlement of the ground during its service life, and determining the length of the protrusions commensurate with the amount of settlement. Designed. As shown in Fig. 3, these protrusions 3 have a predetermined thickness and are spread over a wide area in order to minimize the decrease in the contact area due to the gap 9 between the footing bottom and the ground 8 caused by ground subsidence. It is desirable to provide them so that they are distributed over an area of .
本発明に係る杭基礎をもつ構造体は、上記のようにフー
チング底面から地盤中に向けて予じめ所定の長さをもつ
多数本の突起物３を突設したので、圧密沈下によってフ
ーチング底面と地盤との間に空隙が生じた場合でも、全
ての突起物３の断面を加算した分だけ実質的にフーチン
グ底面は依然として地盤と接触状態を維持していること
となる。In the structure with a pile foundation according to the present invention, a large number of protrusions 3 having a predetermined length are provided in advance from the bottom of the footing into the ground as described above, so that the bottom of the footing is lowered due to consolidation settlement. Even if a gap is created between the footing and the ground, the footing bottom still remains in contact with the ground by the sum of the cross sections of all the protrusions 3.
従って地盤沈下に伴うフーチング底面と地盤との接触面
積の減少を突起物と地盤との接触によって補うことがで
き、本来杭基礎が初期に保持していた振動抑制能力とし
ての減衰効果が大幅に低下させることがなく、耐震性能
を長期間にわたって保持することができる。Therefore, the reduction in the contact area between the bottom of the footing and the ground due to ground subsidence can be compensated for by the contact between the protrusions and the ground, and the damping effect originally held by pile foundations as a vibration suppressing ability is significantly reduced. It is possible to maintain seismic performance for a long period of time without causing damage.
第１図は本発明に係る杭基礎構造の実施例を示す断面図
、第２図は第１図のｎ−ｎ線における断面図、第３図は
地盤が沈下した状態における第１図と同じ部分の断面図
である。
１：フーチング、２：抗、３：突起物、４：捨コンクリ
ート、５：割栗石、
６：地表面、７：支持層、８：地盤、
９：空隙。Fig. 1 is a cross-sectional view showing an embodiment of the pile foundation structure according to the present invention, Fig. 2 is a cross-sectional view taken along line nn in Fig. 1, and Fig. 3 is the same as Fig. 1 in a state where the ground has subsided. FIG. 1: footing, 2: counter, 3: protrusion, 4: waste concrete, 5: split stone, 6: ground surface, 7: support layer, 8: ground, 9: void.
Claims (1)
の地盤中に向けて、予じめ所定の長さをもつ多数本の突
起物を突設しておき、地盤の圧密沈下によって生ずるフ
ーチング底面と地盤との接触面積の減少を補うことを特
徴とした杭基礎の耐震性能保持構造。(1) A large number of protrusions of a predetermined length are provided in advance from the bottom of the footing supported by the piles into the ground between the piles, and the bottom surface of the footing is created by consolidation subsidence of the ground. A structure that maintains seismic performance for pile foundations, which is characterized by compensating for the reduction in the contact area between the pile foundation and the ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21521785A JPS6278322A (en) | 1985-09-30 | 1985-09-30 | Earthquake-proofing structure of pile foundation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21521785A JPS6278322A (en) | 1985-09-30 | 1985-09-30 | Earthquake-proofing structure of pile foundation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6278322A true JPS6278322A (en) | 1987-04-10 |
Family
ID=16668635
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21521785A Pending JPS6278322A (en) | 1985-09-30 | 1985-09-30 | Earthquake-proofing structure of pile foundation |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6278322A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10221753B2 (en) | 2016-04-28 | 2019-03-05 | Subaru Corporation | Vehicle |
-
1985
- 1985-09-30 JP JP21521785A patent/JPS6278322A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10221753B2 (en) | 2016-04-28 | 2019-03-05 | Subaru Corporation | Vehicle |
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