JPH0211691B2 - - Google Patents
Info
- Publication number
- JPH0211691B2 JPH0211691B2 JP7893984A JP7893984A JPH0211691B2 JP H0211691 B2 JPH0211691 B2 JP H0211691B2 JP 7893984 A JP7893984 A JP 7893984A JP 7893984 A JP7893984 A JP 7893984A JP H0211691 B2 JPH0211691 B2 JP H0211691B2
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- protective layer
- pipe pile
- coated steel
- density polyethylene
- 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 34
- 239000010959 steel Substances 0.000 claims description 34
- 239000011241 protective layer Substances 0.000 claims description 30
- 239000000463 material Substances 0.000 claims description 22
- 229920006311 Urethane elastomer Polymers 0.000 claims description 12
- 229920001684 low density polyethylene Polymers 0.000 claims description 12
- 239000004702 low-density polyethylene Substances 0.000 claims description 12
- 239000012791 sliding layer Substances 0.000 claims description 12
- 229920005601 base polymer Polymers 0.000 claims description 7
- 229920001228 polyisocyanate Polymers 0.000 claims description 3
- 239000005056 polyisocyanate Substances 0.000 claims description 3
- 229920005862 polyol Polymers 0.000 claims description 3
- 230000002093 peripheral effect Effects 0.000 claims description 2
- 150000003077 polyols Chemical class 0.000 claims description 2
- 239000003190 viscoelastic substance Substances 0.000 claims description 2
- 229920001903 high density polyethylene Polymers 0.000 description 9
- 239000004700 high-density polyethylene Substances 0.000 description 9
- 239000010410 layer Substances 0.000 description 9
- 238000007765 extrusion coating Methods 0.000 description 5
- 238000000576 coating method Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 description 1
- 239000005062 Polybutadiene Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000002075 main ingredient Substances 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000003415 peat Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920002857 polybutadiene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010734 process oil Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 description 1
- 229940006076 viscoelastic substance Drugs 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/60—Piles with protecting cases
Landscapes
- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Piles And Underground Anchors (AREA)
Description
（産業上の利用分野）
本発明は鋼管杭の中で、特に軟弱地盤における
負摩擦力を軽減するための被覆鋼管杭に関するも
のである。
（従来技術）
軟弱地盤、たとえば粘土層、泥炭層などの上に
大型構造物を建設する場合には、一般にコンクリ
ートあるいは鋼製の基礎杭が使用されるが、地盤
が軟弱なために地層の圧密により地壁沈下が起こ
り、その結果、基礎杭に下方向へ摩擦力すなわち
負摩擦力が作用し、基礎杭の支持力を著しく低下
させるため、杭の沈下もしくは座屈が誘発され
る。
従来、このような負摩擦力を軽減するための被
覆鋼管杭の例としては、鋼管杭体のの外周面にビ
チユーメンからなる被覆層を塗布形成したもの
（英国特許第900665号）、鋼管杭体の外周面にビチ
ユーメンからなる滑り層およびその上に高密度ポ
リエチレン樹脂からなる保護層を形成したもの
（実開昭54−93210号公報、実開昭56−171835号公
報（実施例））が知られている。ここで、高密度
ポリエチレンとは一般にベースポリマー（顔料や
添加剤を加えていない純粋なポリマー）の密度が
0.940〜0.965ｇ／cm3のものを指す。しかし、前者
は夏場にビチユーメン層が流れて運搬が困難であ
ることの他に、打ち込み時に滑り層が変形・剥離
したり、土や石が食い込むなどの欠点がある。そ
して、後者は前者の欠点を改良したものである
が、高密度ポリエチレンの冷却固化時の収縮によ
り、滑り層を必要以上に拘束して、本来滑り層が
有している滑り性能を低下させるという欠点があ
る。たとえば、ベースポリマーの密度が0.940
ｇ／cm3以上の時にはポリエチレン保護層の収縮応
力は220Kg／cm2以上となり、滑り性能が著しく低
下する。
すなわち、高密度ポリエチレンのような収縮応
力が大きい材料を用いた場合、滑り層に対する保
護層の締付け力が大きくなつて、スパイラル状の
ビード部において保護層に引つ掛かりが生じ、滑
り性能を著しく損うこと、およびスパイラル状の
ビード部が存在しない場合でも、鋼管杭表面の滑
り層が薄い部分でやはり引つ掛かりが生じるため
に滑り性能が低下し、滑り層を厚くしなければな
らなくなる。
（発明の目的）
本発明は上記の如き欠点を解決した、良好な滑
り性能を有する被覆鋼管杭を提供することを目的
とするものである。すなわち、本発明は従来の高
密度ポリエチレンからなる保護層が滑り層の性能
を低下させる原因を究明し、その欠点を取り除く
べく検討した結果、保護層が収縮応力を特定する
ことによつて良好な滑り性能を有する負摩擦力を
軽減するための被覆鋼管杭が得られることを見出
したものである。
（発明の構成）
本発明は杭体の外周面に粘弾性物質からなる滑
り層を形成し、さらにその外表面に保護層を形成
させた被覆鋼管杭において、保護層内の残留歪に
よる収縮応力が常温で150Kg／cm2以下であること、
保護層用材料としてベースポリマーの密度が
0.935ｇ／cm3以下の低密度ポリエチレンを使用す
ること、および保護層用材料としてウレタンエラ
ストマーを使用することを特徴とする負摩擦力を
軽減するための被覆鋼管杭である。
以下本発明の被覆鋼管杭について、図面にもと
づいて詳細に説明する。第１図は本発明の被覆鋼
管杭であり、１は鋼管杭、２は滑り層、３は保護
層である。
本発明において、保護層３の材料としては、被
覆後の残留歪による収縮応力が常温で150Kg／cm2
以下であり、かつ運搬・施工中に滑り層のにじみ
出しなどを防止できるものであればどのようなも
のでよいが、実用的にはベースポリマーの密度が
0.935ｇ／cm3以下の低密度ポリエチレン、ポリオ
ールとポリイソシアネートを反応させることによ
つて得られるウレタンエラストマーなどを用いる
ことができる。ここで低密度ポリエチレンとは一
般ベースポリマーの密度が0.910〜0.935ｇ／cm3の
ものを指す。保護層３として、低密度ポリエチレ
ンを押出被覆する方法は、低コストでかつ滑り層
に対して良好な保護効果が得られらるものでもつ
とも好ましいが、押出機やダイなどの被覆設備が
大がかりになるので、このような被覆設備が無い
場合には、厚膜の保護層を小規模な装置で能率よ
く得られるウレタンエラストマーのスプレー塗装
法を適用することが望ましい。
低密度ポリエチレンとしてはホモポリマーの他
に少量の酢酸ビニルと共重合させたものも使用で
きる。そして、必要に応じてカーボンブラツク、
紫外線吸収剤、酸化防止剤などを添加することが
ある。またウレタンエラストマーとしてはポリプ
ロピレングリコール、ポリブタジエングリコール
など分子内に２個以上の水酸基を有するポリオー
ル化合物を主剤とし、トリレンジイソシアネー
ト、ジフエニルメタンジイソシアネートなどのポ
リイソシアネート化合物を硬化剤とする二液型塗
料を反応硬化させたものを用いることができる。
そして塗装性および被覆層の性能の改善のために
プロセスオイル、炭酸カルシウム、無水石こう、
マイカ粉などを添加したものも用いることができ
る。
本発明において、保護層内の残留歪による収縮
応力が常温で150Kg／cm2以下と限定した理由は、
収縮応力が常温で160Kg／cm2のときには、滑り層
厚さを２mmとした場合に沈下速度20cm／年の地盤
中において１年後の負摩擦力が70％程度軽減され
るが、収縮応力が常温で150Kg／cm2のときには負
摩擦力が90％程度に軽減されるため、収縮応力が
常温で150Kg／cm2以下であれば充分効果を発揮す
ることができるからである。
そして、特許請求の範囲第２項の実施態様で、
保護層用材料として、ベースポリマーの密度が
0.935ｇ／cm3以下の低密度ポリエチレンと限定し
たのは、該低密度ポリエチレンの弾性率が小さい
ので、残留応力が150Kg／cm2以下になることの他
に、押出被覆法によつて低コストで能率良く被覆
できるという大きな特長であるからである。
また、特許請求の範囲第３項の実施態様で、保
護層用材料としてウレタンエラストマーと限定し
たのは、ウレタンエラストマーの内部にゴム成分
があるために、反応硬化時に収縮が起つてもすみ
やかに応力緩和が進行して残留応力がほとんどゼ
ロになるためである。そして、前述したようにウ
レタンエラストマーは比較的簡単な設備で厚膜を
能率良く被覆できるので、押出被覆設備が無い場
合にはウレタンエラストマー被覆法を適用するこ
とが好ましい。
一方、低密度ポリエチレンやウレタンエラスト
マーは高密度ポリエチレンに比べて弾性率が低い
ので、土壌中に打ち込む場合に保護層が破れると
いう懸念があつたが、本発明者らの検討では、杭
の先端に従来から用いられている鋼製の保護リン
グを取り付ければ打設時の保護層の破断が生じな
いことが明らかになつている。
次に本発明を実施例で詳しく説明する。
（実施例）
外径711mm、肉厚12mmの鋼管杭にアスフアルト
系で軟化点60℃、針入度90の滑り層材料を厚さ２
mmに被覆した後、第１表に示す保護層を被覆を施
して負摩擦力を軽減する被覆鋼管杭を作成した。
これらの被覆鋼管杭の先端に鋼製の保護リング
を取り付けて地盤沈下の大きい（沈下速度20cm／
年）地盤に打ち込んだ。それぞれの被覆鋼管杭を
複数打設し、その中の１本を引き抜いて被覆表面
を観察したところ、いずれも被覆層表面に微少な
すり疵がある他は、被覆層の破れやめくれはいつ
さい認められなかつた。
１年経過後に、これらの被覆鋼管杭にかかる圧
縮方向の軸力を測定した結果を第１表に示す。な
お、表中の収縮応力は被覆鋼管杭から保護層を切
り取つて（大きさ10cm×10cm）、沸とう水に30分
間浸漬し、このときの管周方向の収縮量から残留
歪を算出し、この値に保護層材料の15℃における
引張弾性率を乗じて得られた値である。
(Industrial Application Field) The present invention relates to steel pipe piles, particularly coated steel pipe piles for reducing negative frictional force in soft ground. (Prior art) When constructing a large structure on soft ground, such as a clay layer or a peat layer, concrete or steel foundation piles are generally used. This causes ground wall subsidence, and as a result, a downward frictional force, that is, a negative frictional force, acts on the foundation pile, significantly reducing the supporting capacity of the foundation pile, inducing sinking or buckling of the pile. Conventionally, examples of coated steel pipe piles for reducing such negative friction forces include those in which a coating layer made of bitumen is applied to the outer peripheral surface of the steel pipe pile body (British Patent No. 900665), and steel pipe pile bodies. A slip layer made of bitiumen and a protective layer made of high density polyethylene resin formed on the outer circumferential surface of the slide (Utility Model Application Publication No. 54-93210, Publication of Utility Model Application No. 56-171835 (examples)) are known. It is being Here, high-density polyethylene generally refers to the density of the base polymer (pure polymer without added pigments or additives).
Refers to 0.940-0.965g/ cm3 . However, the former has drawbacks such as the fact that the bityumen layer washes away in the summer, making it difficult to transport, and the sliding layer deforms and peels off during driving, and soil and stones dig into it. The latter improves on the drawbacks of the former, but the shrinkage of high-density polyethylene when it cools and solidifies restricts the sliding layer more than necessary, reducing the slipping performance that the sliding layer originally has. There are drawbacks. For example, if the density of the base polymer is 0.940
g/cm 3 or more, the shrinkage stress of the polyethylene protective layer becomes 220 Kg/cm 2 or more, and the sliding performance is significantly reduced. In other words, when a material with high shrinkage stress such as high-density polyethylene is used, the tightening force of the protective layer against the sliding layer becomes large, causing the protective layer to catch on the spiral bead, significantly reducing the sliding performance. Even if there is no spiral bead, the sliding layer on the surface of the steel pipe pile still gets caught in thin areas, resulting in a decrease in sliding performance and the need to thicken the sliding layer. (Object of the Invention) An object of the present invention is to provide a coated steel pipe pile having good sliding performance, which solves the above-mentioned drawbacks. That is, the present invention has investigated the cause of the deterioration of the performance of the slipping layer in the conventional protective layer made of high-density polyethylene, and as a result of studies to eliminate the drawbacks, it has been found that the protective layer has good properties by specifying the shrinkage stress. It has been discovered that a coated steel pipe pile with sliding performance for reducing negative frictional force can be obtained. (Structure of the Invention) The present invention provides a coated steel pipe pile in which a sliding layer made of a viscoelastic substance is formed on the outer circumferential surface of the pile body, and a protective layer is further formed on the outer surface of the pile body. is less than 150Kg/ cm2 at room temperature,
The density of the base polymer as a material for the protective layer
This is a coated steel pipe pile for reducing negative friction force, characterized by using low density polyethylene of 0.935 g/cm 3 or less and using urethane elastomer as a material for the protective layer. The coated steel pipe pile of the present invention will be explained in detail below based on the drawings. FIG. 1 shows a coated steel pipe pile of the present invention, where 1 is a steel pipe pile, 2 is a sliding layer, and 3 is a protective layer. In the present invention, the material for the protective layer 3 has a shrinkage stress of 150 kg/cm 2 at room temperature due to residual strain after coating.
Any material may be used as long as it satisfies the following and can prevent the slipping layer from oozing out during transportation and construction, but in practical terms, the density of the base polymer is
Low-density polyethylene of 0.935 g/cm 3 or less, urethane elastomer obtained by reacting polyol and polyisocyanate, etc. can be used. Here, low density polyethylene refers to a general base polymer having a density of 0.910 to 0.935 g/cm 3 . The method of extrusion coating low-density polyethylene as the protective layer 3 is preferable because it is low cost and provides a good protective effect for the slip layer, but it requires large-scale coating equipment such as an extruder and die. Therefore, if such coating equipment is not available, it is desirable to apply a urethane elastomer spray coating method that can efficiently obtain a thick protective layer using small-scale equipment. As the low density polyethylene, in addition to homopolymers, those copolymerized with a small amount of vinyl acetate can also be used. And if necessary, carbon black,
Ultraviolet absorbers, antioxidants, etc. may be added. In addition, urethane elastomers include two-component paints whose main ingredient is a polyol compound having two or more hydroxyl groups in the molecule, such as polypropylene glycol or polybutadiene glycol, and whose curing agent is a polyisocyanate compound such as tolylene diisocyanate or diphenylmethane diisocyanate. A reaction-cured material can be used.
and process oil, calcium carbonate, anhydrous gypsum, to improve paintability and coating layer performance.
A material to which mica powder or the like is added can also be used. In the present invention, the reason why the shrinkage stress due to residual strain in the protective layer is limited to 150Kg/cm 2 or less at room temperature is as follows.
When the shrinkage stress is 160Kg/ cm2 at room temperature, if the sliding layer thickness is 2mm, the negative friction force will be reduced by about 70% after one year in the ground with a subsidence rate of 20cm/year. This is because the negative friction force is reduced to about 90% when the stress is 150 Kg/cm 2 at room temperature, so if the shrinkage stress is 150 Kg/cm 2 or less at room temperature, sufficient effects can be exhibited. And, in the embodiment of claim 2,
As a material for the protective layer, the density of the base polymer
The reason why we limited it to low-density polyethylene of 0.935 g/cm 3 or less is that the modulus of elasticity of the low-density polyethylene is small, so the residual stress is 150 Kg/cm 2 or less, and the extrusion coating method is low cost. This is because its major feature is that it can be coated efficiently. In addition, in the embodiment of claim 3, the material for the protective layer is limited to urethane elastomer because there is a rubber component inside the urethane elastomer, so even if shrinkage occurs during reaction curing, it can quickly absorb stress. This is because the relaxation progresses and the residual stress becomes almost zero. As mentioned above, since urethane elastomer can efficiently coat a thick film with relatively simple equipment, it is preferable to apply the urethane elastomer coating method when extrusion coating equipment is not available. On the other hand, since low-density polyethylene and urethane elastomer have a lower elastic modulus than high-density polyethylene, there was a concern that the protective layer would tear when driven into the soil. It has become clear that if a conventionally used steel protective ring is attached, the protective layer will not break during pouring. Next, the present invention will be explained in detail with reference to Examples. (Example) A steel pipe pile with an outer diameter of 711 mm and a wall thickness of 12 mm is coated with an asphalt-based sliding layer material with a softening point of 60°C and a penetration rate of 90 to a thickness of 2.
mm, and then coated with the protective layer shown in Table 1 to create a coated steel pipe pile that reduces negative frictional force. A steel protection ring is attached to the tip of these coated steel pipe piles to prevent large ground subsidence (sinking rate of 20cm/
year) was driven into the ground. When we drove multiple coated steel pipe piles of each type and pulled out one of them to observe the coated surface, we found that there were only slight scratches on the coated layer surface, and no tears or cracks in the coated layer. It wasn't recognized. Table 1 shows the results of measuring the axial force in the compressive direction applied to these coated steel pipe piles after one year. The shrinkage stress in the table is calculated by cutting the protective layer from a coated steel pipe pile (size 10cm x 10cm), immersing it in boiling water for 30 minutes, and calculating the residual strain from the amount of shrinkage in the circumferential direction of the pipe. This value is obtained by multiplying this value by the tensile modulus of the protective layer material at 15°C.
【表】
同時に試験を行つた無被覆鋼管杭の１年後の圧
縮方向の軸力は170トンであつたので、比較材で
ある高密度ポリエチレン被覆材の軸力は65〜70％
程度軽減されているにすぎないが、本発明の低密
度ポリエチレン被覆材およびウレタンエラストマ
ー被覆材の軸力は90％以上軽減されており、本発
明による被覆鋼管杭は負摩擦力が著しく低下して
いることが明らかになつた。
（発明の効果）
本発明は以上に述べたような構成を有する被覆
鋼管杭であるから、従来の保護層用材料として高
密度ポリエチレンを使用した被覆鋼管杭に比べて
はるかに優れた滑り性能を有しているために地盤
沈下の大きい軟弱地盤に対しても安心して使用で
きる。そして、本発明による被覆鋼管杭は滑り性
能が優れているために地盤沈下がそれほど大きく
ない地盤に対しては従来の保護層用材料として高
密度ポリエチレンを使用した被覆鋼管杭に比べて
滑り層を薄くできるという経済的なメリツトもあ
る。
そして、保護層用材料として低密度ポリエチレ
ンを使用する場合には材料が安価である他に、押
出被覆法により生産性良く被覆できるという長所
がある。また、保護層用材料としてウレタンエラ
ストマーを使用する場合は、材料単価は低密度ポ
リエチレンよりも高価であるが、押出被覆設備の
ような大規模な設備が無い場合でも、比較的簡単
な設備で厚膜を能率良く被覆できるという長所が
ある。[Table] The axial force in the compression direction of the uncoated steel pipe pile tested at the same time after one year was 170 tons, so the axial force of the high-density polyethylene sheathing material used as a comparison material was 65 to 70%.
Although the axial force of the low-density polyethylene sheathing material and urethane elastomer sheathing material of the present invention has been reduced by more than 90%, the coated steel pipe pile of the present invention has significantly reduced negative frictional force. It became clear that there was. (Effects of the Invention) Since the present invention is a coated steel pipe pile having the configuration described above, it has far superior sliding performance compared to the conventional coated steel pipe pile using high-density polyethylene as the material for the protective layer. Because of this, it can be used safely even on soft ground with large ground subsidence. Since the coated steel pipe pile according to the present invention has excellent sliding performance, it can be used for ground where ground subsidence is not so large compared to the conventional coated steel pipe pile that uses high-density polyethylene as the material for the protective layer. It also has the economic advantage of being thinner. When low-density polyethylene is used as the material for the protective layer, it has the advantage that it is inexpensive and can be coated with high productivity by extrusion coating. In addition, when using urethane elastomer as a material for the protective layer, the unit price of the material is more expensive than low-density polyethylene, but even if large-scale equipment such as extrusion coating equipment is not available, it is possible to thicken the film with relatively simple equipment. It has the advantage of being able to coat the film efficiently.
第１図は本発明による被覆鋼管杭の一部断面斜
視図である。
１…鋼管杭、２…滑り層、３…保護層。
FIG. 1 is a partially sectional perspective view of a coated steel pipe pile according to the present invention. 1... Steel pipe pile, 2... Sliding layer, 3... Protective layer.
Claims (1)
形成し、さらにその外表面に保護層を形成させた
被覆鋼管杭において、保護層内の残留歪による収
縮応力が常温で150Kg／cm2以下であることを特徴
とする負摩擦力を軽減するための被覆鋼管杭。 ２ 保護層用材料としてベースポリマーの密度が
0.935ｇ／cm3以下の低密度ポリエチレンを使用す
ることを特徴とする特許請求の範囲第１項に記載
の負摩擦力を軽減する被覆鋼管杭。 ３ 保護層用材料として、ポリオールとポリイソ
シアネートを反応させることによつて得られるウ
レタンエラストマーを使用することを特徴とする
特許請求の範囲第１項記載の負摩擦力を軽減する
被覆鋼管杭。[Claims] 1. In a coated steel pipe pile in which a sliding layer made of a viscoelastic material is formed on the outer peripheral surface of the pile body and a protective layer is further formed on the outer surface of the pile, shrinkage stress due to residual strain in the protective layer is A coated steel pipe pile for reducing negative friction force, which is 150Kg/cm 2 or less at room temperature. 2 The density of the base polymer as a material for the protective layer
The coated steel pipe pile for reducing negative friction force according to claim 1, characterized in that low density polyethylene of 0.935 g/cm 3 or less is used. 3. A coated steel pipe pile for reducing negative frictional force according to claim 1, characterized in that a urethane elastomer obtained by reacting polyol and polyisocyanate is used as the material for the protective layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7893984A JPS60223521A (en) | 1984-04-19 | 1984-04-19 | Clad steel-pipe pile of relieved negative frictional force |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7893984A JPS60223521A (en) | 1984-04-19 | 1984-04-19 | Clad steel-pipe pile of relieved negative frictional force |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60223521A JPS60223521A (en) | 1985-11-08 |
| JPH0211691B2 true JPH0211691B2 (en) | 1990-03-15 |
Family
ID=13675848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7893984A Granted JPS60223521A (en) | 1984-04-19 | 1984-04-19 | Clad steel-pipe pile of relieved negative frictional force |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60223521A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002013675A (en) * | 2000-04-28 | 2002-01-18 | Sekisui Chem Co Ltd | Composite high-pressure pipe |
| US9903086B2 (en) | 2015-07-16 | 2018-02-27 | Foundation Technologies, Inc. | Friction reduction pile jacket with slip additive |
-
1984
- 1984-04-19 JP JP7893984A patent/JPS60223521A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60223521A (en) | 1985-11-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |