JPS6212003B2 - - Google Patents
Info
- Publication number
- JPS6212003B2 JPS6212003B2 JP54043619A JP4361979A JPS6212003B2 JP S6212003 B2 JPS6212003 B2 JP S6212003B2 JP 54043619 A JP54043619 A JP 54043619A JP 4361979 A JP4361979 A JP 4361979A JP S6212003 B2 JPS6212003 B2 JP S6212003B2
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- filler
- force
- composite pile
- internal pressure
- 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.)
- Expired
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 58
- 239000010959 steel Substances 0.000 claims description 58
- 239000000945 filler Substances 0.000 claims description 40
- 239000000463 material Substances 0.000 claims description 12
- 239000002131 composite material Substances 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 4
- 230000002093 peripheral effect Effects 0.000 claims description 2
- 230000001133 acceleration Effects 0.000 description 4
- 230000008602 contraction Effects 0.000 description 3
- 239000004570 mortar (masonry) Substances 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Description
この発明は鋼管の内周面にコンクリート、モル
タル等の充填材を打設して内部を密封し、密封内
部の圧力を充填分に高めて鋼管を外方に膨脹させ
た状態で充填材を養生硬化させ、養生硬化した充
填材の強度が充分に発現したとき内圧を除去し、
鋼管の収縮力を硬化した充填材に圧縮力として作
用させ、プレストレスを与えるようにした鋼管複
合パイルの製造法に関するものである。
周知の様に鋼管の内周面にコンクリートやモル
タルなどの充填材を筒状に打設した鋼管複合パイ
ルは、鋼管と充填材の材質特性を充分に発揮させ
なければ強度有るものとはならない。このために
は鋼管と充填材との境界における付着力が最も重
要となる。
従来、鋼管と充填材との付着力を高めるため、
鋼管の内面に凹凸を形成したり、又は膨脹剤を混
入したコンクリートを鋼管内面に打設して養生に
よりコンクリート膨脹させていた。またコンクリ
ート強度を高めるため鋼管内部を高温、高圧状態
にして養生していた。しかしいずれの方法も十分
な強度を発現することができず、鋼管複合パイル
の要件である両材質の特性を相互に作用させるこ
とができない。
本発明は上記に鑑み提案されたもので、鋼管の
収縮力を充填材に圧縮力として作用させ、この圧
縮力を充填材にプレストレスとして与えるように
したから、鋼管と充填材との特性が相俟つて作用
し、著しく強度有るものとなる。
本発明の鋼管複合パイルの製造法を具体的に説
明すると、先ず一端又は両端が開放した鋼管１の
内周面にコンクリート、モルタル等の充填材２を
筒状に打設する。その後この鋼管の開放面のほと
んどを気密に閉塞したら、一部の開放部分から圧
縮空気又は水蒸気を供給して鋼管の内部圧力を充
分に高めて密封し、その後鋼管を、中心軸にして
高速回転させ、遠心力により未硬化状態の充填材
２を鋼管１の内面に密着させる。この状態では鋼
管が内圧によつて弾性限界内で外方に膨脹し、ま
た充填材が膨脹した鋼管内周面に押圧して密接し
ている。
この場合、鋼管の内圧を−ｐとすると、鋼管に
は内周方向にＴ＝−ｐ・ｒ（但しｒは鋼管の半
径）の引張力が作用している（第１図）。しかし
充填材は未硬化なので、内部応力が生じていな
い。
このように内圧を充分に高めて鋼管を外方に膨
脹し、また内部の充填材を内面に密着状としたら
そのまゝ放置して自然養生したり、或いは加熱養
生して充填材を硬化させる。そして充填材が硬化
して強度が充分に発現したら端部を開放して気密
状態を解除し、内圧を除去して大気圧とする。
内圧を除去すると膨脹していた鋼管は収縮し、
この収縮力が充填材に＋ｐの外圧を与えることに
なり、この外圧により充填材に２軸方向の圧縮応
力を作用させ、同時に鋼管と充填材とに強固な付
着力が生じる。充填材２に作用する２軸方向の圧
縮力としては鋼管の収縮力に基ずく中心方向に向
う力と円周方向に沿う力とである（第２図）。
したがつて鋼管と充填材とは実質的に一体化さ
れるように強固に付着し、また充填材には常に圧
縮応力が生じていることになり、強度有る鋼管複
合パイルを製造することができる。
上記した製造法において、内部圧力が十分に高
まつている鋼管を高速回転させる速度は、等速円
運動における加速度αが15Gから45G（但しＧは
重力加速度で980cm／sec2）となる範囲である。
鋼管の高速回転時の速度の加速度αが15G以下
では回転速度が遅いので充填材を鋼管の内面に充
分に密着させることができないし、上記加速度が
αが45G以上であれば設備が大規模になるし、
45G以上にすることによる効果がない。
次に本発明の具体的例を説明する。
第３図で示すように充填材２を肉厚な円筒と
し、鋼管１により全周面に外圧ｐを受けているも
のとする。この状態では円筒状充填材２には円周
方向圧縮力σt、及び半径方向圧縮力σrが作用
し、各圧縮力は下記の式で表わされる。
上記式においてr1は充填材の内半径、r2は充填
材の外半径、ｒは充填材内の任意の位置での半径
で、r1≦ｒ≦r2である。
σtの最大はｒ＝r1である内面に、σrの最大は
ｒ＝r1の外面に各々生じ、この値（σt）nax、（σ
r）nioは第(1)式から下記の様になる。
一方、σtの最小はｒ＝r2である外面に、σrの
最少はｒ＝r1の内面に各々生じ、この値（σt）ni
ｏ、（σr）nioは第(1)式から下記の様になる。
上記で明らかなように、外圧ｐが作用したとき
円筒状充填材に生じる円周方向圧縮力σt及び半
径方向圧縮力σrは外圧ｐ及び円筒の径との函数
であり、充填材や鋼管の材質、性状などには直接
関係がない。
そして、r1＝9.9cm、r2＝15.3cmのコンクリート
管の周面に鋼管の収縮力による外圧ｐ＝10Kg／cm2
を作用させると、前記第(2)式、第(3)式より
（σt）nax＝34.4Kg／cm2 （σt）nio＝24.4Kg／cm2
（σr）nax＝10.0Kg／cm2 （σr）nio＝０
の圧縮応力がコンクリート管に作用する。
したがつて本発明により製造した鋼管複合パイ
ルのコンクリートには、内面に円周方向の圧縮応
力34.4Kg／cm2が、外面に円周方向の圧縮応力24.4
Kg／cm2が常に導入されていることになり、この圧
縮応力がプレストレスとして作用する。
次に鋼管により外周面にＰ＝10Kg／cm2の外圧を
受けている本発明の鋼管複合パイル（cp−３、
cp−４、cp−５の３種類）と、従来からあるオ
ートクレーブ養生により製造した鋼管複合パイル
Ｅとを試験体としたとき、試験結果を下記の表に
示し、また各試験体の曲げ耐力を比較するために
たわみ試験結果を第４図のグラフに示す。
In this invention, a filler material such as concrete or mortar is placed on the inner circumferential surface of a steel pipe to seal the inside, and the pressure inside the seal is increased to the amount of the filling material, and the filler material is cured while the steel pipe expands outward. When the strength of the cured filler material has been sufficiently developed, the internal pressure is removed.
This invention relates to a method for manufacturing a steel pipe composite pile in which the shrinkage force of the steel pipe acts on a hardened filler as a compressive force to apply prestress. As is well known, a steel pipe composite pile, in which a filler material such as concrete or mortar is placed in a cylindrical shape on the inner peripheral surface of a steel pipe, will not have sufficient strength unless the material properties of the steel pipe and filler are fully utilized. For this purpose, the adhesion force at the boundary between the steel pipe and the filler material is most important. Conventionally, in order to increase the adhesion between the steel pipe and the filler,
The inner surface of the steel pipe is made uneven, or concrete mixed with an expanding agent is poured onto the inner surface of the steel pipe, and the concrete is expanded by curing. In addition, to increase the strength of the concrete, the inside of the steel pipes was cured at high temperatures and pressures. However, neither method is able to develop sufficient strength, and it is not possible to make the characteristics of both materials interact, which is a requirement for steel pipe composite piles. The present invention was proposed in view of the above, and the shrinkage force of the steel pipe acts on the filler as a compressive force, and this compressive force is applied to the filler as prestress, so that the characteristics of the steel pipe and the filler are improved. They work together and become extremely strong. To specifically explain the method for manufacturing the steel pipe composite pile of the present invention, first, a filler material 2 such as concrete or mortar is placed in a cylindrical shape on the inner circumferential surface of a steel pipe 1 which is open at one or both ends. After that, most of the open surface of this steel pipe is airtightly closed, compressed air or steam is supplied from some open parts to sufficiently increase the internal pressure of the steel pipe and the steel pipe is sealed, and then the steel pipe is rotated at high speed with the center axis. The unhardened filler 2 is brought into close contact with the inner surface of the steel pipe 1 by centrifugal force. In this state, the steel pipe expands outward within its elastic limit due to the internal pressure, and the filler presses against the expanded inner circumferential surface of the steel pipe and comes into close contact with it. In this case, assuming that the internal pressure of the steel pipe is -p, a tensile force of T=-p·r (where r is the radius of the steel pipe) is acting on the steel pipe in the inner circumferential direction (FIG. 1). However, since the filler is uncured, no internal stress is generated. In this way, the internal pressure is sufficiently increased to expand the steel pipe outward, and once the internal filler is in close contact with the inner surface, it can be left as is for natural curing, or it can be heated and cured to harden the filler. . When the filler hardens and develops sufficient strength, the ends are opened to release the airtight state and the internal pressure is removed to atmospheric pressure. When the internal pressure is removed, the expanding steel pipe contracts,
This contraction force applies an external pressure of +p to the filler, and this external pressure causes biaxial compressive stress to act on the filler, and at the same time, a strong adhesive force is generated between the steel pipe and the filler. The biaxial compressive forces acting on the filler 2 are a force directed toward the center and a force along the circumferential direction based on the contraction force of the steel pipe (FIG. 2). Therefore, the steel pipe and the filler are firmly attached to each other so that they are substantially integrated, and compressive stress is always generated in the filler, making it possible to manufacture a strong steel pipe composite pile. . In the above manufacturing method, the speed at which the steel pipe with sufficiently high internal pressure is rotated is within the range where the acceleration α in uniform circular motion is 15G to 45G (where G is the gravitational acceleration of 980cm/sec 2 ). be. If the acceleration α of the high-speed rotation of the steel pipe is less than 15G, the rotation speed will be slow and the filler will not be able to adhere sufficiently to the inner surface of the steel pipe, and if the acceleration α is more than 45G, the equipment will be large-scale. It becomes,
There is no effect of setting it above 45G. Next, a specific example of the present invention will be explained. As shown in FIG. 3, the filler 2 is assumed to be a thick cylinder, and the entire circumferential surface of the filler 2 is subjected to an external pressure p by the steel pipe 1. In this state, a circumferential compressive force σ t and a radial compressive force σ r act on the cylindrical filler 2, and each compressive force is expressed by the following equation. In the above formula, r 1 is the inner radius of the filler, r 2 is the outer radius of the filler, r is the radius at any position within the filler, and r 1 ≦r≦r 2 . The maximum of σ t occurs on the inner surface where r=r 1 , and the maximum of σ r occurs on the outer surface with r=r 1 , and these values (σ t ) nax , (σ
r ) nio is obtained from equation (1) as follows. On the other hand, the minimum of σ t occurs on the outer surface where r = r 2 , and the minimum of σ r occurs on the inner surface with r = r 1 , and this value (σ t ) ni
o and (σ r ) nio are as follows from equation (1). As is clear from the above, the circumferential compressive force σ t and the radial compressive force σ r generated on the cylindrical filler when external pressure p is applied are functions of the external pressure p and the diameter of the cylinder, and are a function of the filler and the steel pipe. It has no direct relation to the material, properties, etc. Then, external pressure p = 10 Kg/cm 2 due to the contraction force of the steel pipe is applied to the circumferential surface of the concrete pipe with r 1 = 9.9 cm and r 2 = 15.3 cm.
From equations (2) and (3) above, (σ t ) nax = 34.4Kg/cm 2 (σ t ) nio = 24.4Kg/cm 2 (σ r ) nax = 10.0Kg/cm A compressive stress of 2 (σ r ) nio = 0 acts on the concrete pipe. Therefore, the concrete of the steel pipe composite pile manufactured according to the present invention has a circumferential compressive stress of 34.4 kg/cm 2 on the inner surface and a circumferential compressive stress of 24.4 kg/cm 2 on the outer surface.
Kg/cm 2 is always introduced, and this compressive stress acts as prestress. Next, the steel pipe composite pile of the present invention (cp-3,
The test results are shown in the table below, and the bending strength of each test piece is shown in the table below. For comparison, the deflection test results are shown in the graph of FIG.
【表】
上記した表及び第４図のグラフから明らかなよ
うに、本発明により製造した鋼管複合パイルは従
来から最も強度有るといわれているオートクレー
ブ養生により製造した鋼管複合パイルより曲げ耐
力及びたわみ性状がかなりすぐれていることが明
らかである。
また本発明は、気体により鋼管の内圧を高める
ので、鋼管を高速回転して未硬化状態の充填材を
鋼管の内面に密着させることができる。このため
面倒な型抜き工程を行う必要がないし、鋼管の気
密状態を解除するだけで内圧を大気圧に戻すこと
ができる。したがつて高強度の鋼管複合パイルを
一連の工程で効率良く、簡単に製造することがで
きる。[Table] As is clear from the above table and the graph in Figure 4, the steel pipe composite pile manufactured according to the present invention has better bending strength and deflection properties than the steel pipe composite pile manufactured by autoclave curing, which is conventionally said to have the highest strength. It is clear that it is quite superior. Further, in the present invention, since the internal pressure of the steel pipe is increased using gas, the steel pipe can be rotated at high speed to bring the unhardened filler into close contact with the inner surface of the steel pipe. Therefore, there is no need to perform a troublesome die-cutting process, and the internal pressure can be returned to atmospheric pressure simply by releasing the airtight state of the steel pipe. Therefore, a high-strength steel pipe composite pile can be manufactured efficiently and easily through a series of steps.
第１図は内圧を高めた場合の鋼管パイルに引張
力が作用している概略説明図、第２図は鋼管の収
縮応力が充填材に作用している概略説明図、第３
図は外圧が作用したとき円筒状充填材に作用する
圧縮応力分布図、第４図は本発明の試験における
たわみ曲線のグラフである。
Figure 1 is a schematic illustration of tensile force acting on a steel pipe pile when the internal pressure is increased, Figure 2 is a schematic illustration of shrinkage stress of steel pipes acting on filler material, and Figure 3
The figure is a compressive stress distribution diagram that acts on the cylindrical filler when external pressure is applied, and FIG. 4 is a graph of the deflection curve in the test of the present invention.
Claims (1)
の圧力を気体により充分に高めて鋼管を外方に膨
張させた状態で密封し、その後鋼管を高速回転さ
せることにより未硬化状態の充填材を鋼管内面に
密着させて成形し、その後充填材を養生硬化させ
て強度が充分に発現したら鋼管の気密状態を解除
し、鋼管の収縮力を硬化した充填材に圧縮応力と
して作用させるようにしたことを特徴とする鋼管
複合パイルの製造法。1 After placing the filler material on the inner peripheral surface of the steel pipe, the pressure inside the steel pipe is sufficiently increased with gas to expand the steel pipe outward and sealed, and then the steel pipe is rotated at high speed until it is in an unhardened state. The filler is molded in close contact with the inner surface of the steel pipe, and then the filler is cured and hardened, and once it has developed sufficient strength, the airtight state of the steel pipe is released, and the shrinkage force of the steel pipe acts on the hardened filler as compressive stress. A method for manufacturing a steel pipe composite pile, characterized in that:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4361979A JPS55135611A (en) | 1979-04-12 | 1979-04-12 | Preparation of steel pipe compound pile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4361979A JPS55135611A (en) | 1979-04-12 | 1979-04-12 | Preparation of steel pipe compound pile |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS55135611A JPS55135611A (en) | 1980-10-22 |
| JPS6212003B2 true JPS6212003B2 (en) | 1987-03-16 |
Family
ID=12668849
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4361979A Granted JPS55135611A (en) | 1979-04-12 | 1979-04-12 | Preparation of steel pipe compound pile |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS55135611A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8069880B2 (en) * | 2008-04-02 | 2011-12-06 | Ameron International Corporation | Pressure cast concrete or mortar lined steel pipes and methods of making the same |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4732813U (en) * | 1971-05-01 | 1972-12-13 |
-
1979
- 1979-04-12 JP JP4361979A patent/JPS55135611A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4732813U (en) * | 1971-05-01 | 1972-12-13 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS55135611A (en) | 1980-10-22 |
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