CA1227646A - Protected pile and joist bridge shore approach - Google Patents
Protected pile and joist bridge shore approachInfo
- Publication number
- CA1227646A CA1227646A CA000453434A CA453434A CA1227646A CA 1227646 A CA1227646 A CA 1227646A CA 000453434 A CA000453434 A CA 000453434A CA 453434 A CA453434 A CA 453434A CA 1227646 A CA1227646 A CA 1227646A
- Authority
- CA
- Canada
- Prior art keywords
- pipeline
- riser
- piling
- ice
- cone
- 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
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- Foundations (AREA)
Abstract
A B S T R A C T
PROTECTED PILE AND JOIST BRIDGE SHORE APPROACH
A cone protected pile and joist bridge shore approach is provided for oil rig-to-shore pipelines in the Arctic seas. The bridge carries the pipeline far enough offshore to a location where thaw unstable permafrost conditions do no exist.
PROTECTED PILE AND JOIST BRIDGE SHORE APPROACH
A cone protected pile and joist bridge shore approach is provided for oil rig-to-shore pipelines in the Arctic seas. The bridge carries the pipeline far enough offshore to a location where thaw unstable permafrost conditions do no exist.
Description
~22764~i - I
The invention relates to a structure for protecting a pipeline from forces exerted by ice as the pipeline is passed from offshore, under a midline and then through an ice layer to onshore.
Substantial reserves of oil and gas lie below the sun-face of Arctic seas such as the Beau fort Sea. Techniques have been developed for tapping such offshore oil and gas reserves by using either offshore platforms erected on the sea floor or artifi-coal islands. Bringing the produced oil and gas to shore via pipelines in these areas presents new and unusual problems not normally found in most conventional pipeline shore approaches. For at least a major portion of each year, the ice extends downwardly to a midline over a substantial distance from the shoreline. In this region, thaw unstable permafrost exists under a soil layer which seasonally thaws and freezes. Heat from the pipeline thaws the unstable permafrost resulting in gross settlement. Seasonal freezing and thawing at the midline will tend to lift objects, even of considerable weight, which penetrate it, because of the expansion due to freezing water. Moreover structures in this region are subjected to severe ice loads due to movements of the ice when the ice is not fixed to the midline.
According to the invention the structure for protecting a pipeline from forces exerted by ice as the pipeline is passed from offshore, under a soil line and then through an ice layer to onshore, comprising: a series of substantially vertical pilings supporting substantially horizontal joist members; a protective ~LZ2'7~
- lo -cone about each piling, the bottom of the protective cone resting on the soil line and the protective cone having an angle of about 45 and being essentially unconnected to the piling; and SUE
a riser, extending along one of the pilings, for accommo-dating the transition of the pipeline located under the soil line to the pipeline supported by the joist members, wherein the riser extends within the protective cone and wherein the riser is essentially unconnected thereto.
The principal purpose of the present invention is to provide a protected pile and joist bridge shore approach for a pipeline extending from offshore, under the soil line or seafloor and then through an ice layer above thaw unstable soil to onshore. The present invention minimizes the ice loads exerted on the pipeline support structure, protects the pipeline in the transition from buried to elevated mode and prevents thawing of the unstable permafrost.
The invention will be described by way of example in more lo detail with reference to the drawings, wherein jig. 1 shows a side-view of the structure according to the invention; and Fig. 2 shows detail II of Figure 1 on a scale which is larger than the scale of Figure 1.
2Q The present invention provides an elevated shore approach for one or more pipelines in an arctic area characterized by thick ice extending a substantial distance offshore in bottom contact with a soil fins or midline and by thaw unstable soil. As shown in Figure 1, a pipeline 10 approaches from the offshore side at the left hand side of the figure, under a natural midline 11 and a mean waterline 12, to a riser 13 which is parallel to a vertical piling 14. In a preferred embodiment of the invention, the riser 13 is clamped to the piling 14.
Both the piling 14 and the riser 13 pass through a protective 30 cone 15 which rusts on the muslins 11. The protective cone 15 is not attached directly to the piling 14 or to the riser 13, but it is able to heave up and down with a freeze-thaw cycle while still providing protection to the riser 13 and the piling 14 from the ice.
~2Z~76~6 The piling 14 extends upwardly to horizontal joist member 16, which comprises preferably two parallel long-span joists. The riser 13 connects the pipeline 10 to a pipeline 17 which is supported by joist members 16 and conventional sliding shoe support cross members (not shown). Thermal expansion of the pipeline is accommodated with expansion offsets 18 contained within the open area between the joist members 16.
A sectional view of protective cone 15 is shown in Figure 2.
The outside shell of cone 15 and a reinforcing member 20 are preferably at an angle of about 45 degrees with respect to the bottom portion 19 of the cone which rests on the midline 11. The angle of the cone of about 45 degrees minimizes the lateral loads exerted by the ice on the piling and consequently minimizes the required piling diameter, thickness and embedment depth. Bottom portion 19 is further tied to reinforcing member 20 and the cone 15 by a reinforcing member 21.
In the Beau fort Sea on the worth Slope of Alaska, a shore approach begins in about 7 feet water depth and extends approximately one mile to a point 200 feet onshore. A one mile span elevates the pipeline by utilizing 240 feet joist members supported by 6 feet diameter steel piles. A riser extends below the midline to allow a cover of 3 feet over the top of the pipeline. Expansion in the elevated pipeline is allowed by expansion offsets every 480 feet.
The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described apparatus and method may be made within the scope of the appended claims without departing from the spirit of the invention.
The invention relates to a structure for protecting a pipeline from forces exerted by ice as the pipeline is passed from offshore, under a midline and then through an ice layer to onshore.
Substantial reserves of oil and gas lie below the sun-face of Arctic seas such as the Beau fort Sea. Techniques have been developed for tapping such offshore oil and gas reserves by using either offshore platforms erected on the sea floor or artifi-coal islands. Bringing the produced oil and gas to shore via pipelines in these areas presents new and unusual problems not normally found in most conventional pipeline shore approaches. For at least a major portion of each year, the ice extends downwardly to a midline over a substantial distance from the shoreline. In this region, thaw unstable permafrost exists under a soil layer which seasonally thaws and freezes. Heat from the pipeline thaws the unstable permafrost resulting in gross settlement. Seasonal freezing and thawing at the midline will tend to lift objects, even of considerable weight, which penetrate it, because of the expansion due to freezing water. Moreover structures in this region are subjected to severe ice loads due to movements of the ice when the ice is not fixed to the midline.
According to the invention the structure for protecting a pipeline from forces exerted by ice as the pipeline is passed from offshore, under a soil line and then through an ice layer to onshore, comprising: a series of substantially vertical pilings supporting substantially horizontal joist members; a protective ~LZ2'7~
- lo -cone about each piling, the bottom of the protective cone resting on the soil line and the protective cone having an angle of about 45 and being essentially unconnected to the piling; and SUE
a riser, extending along one of the pilings, for accommo-dating the transition of the pipeline located under the soil line to the pipeline supported by the joist members, wherein the riser extends within the protective cone and wherein the riser is essentially unconnected thereto.
The principal purpose of the present invention is to provide a protected pile and joist bridge shore approach for a pipeline extending from offshore, under the soil line or seafloor and then through an ice layer above thaw unstable soil to onshore. The present invention minimizes the ice loads exerted on the pipeline support structure, protects the pipeline in the transition from buried to elevated mode and prevents thawing of the unstable permafrost.
The invention will be described by way of example in more lo detail with reference to the drawings, wherein jig. 1 shows a side-view of the structure according to the invention; and Fig. 2 shows detail II of Figure 1 on a scale which is larger than the scale of Figure 1.
2Q The present invention provides an elevated shore approach for one or more pipelines in an arctic area characterized by thick ice extending a substantial distance offshore in bottom contact with a soil fins or midline and by thaw unstable soil. As shown in Figure 1, a pipeline 10 approaches from the offshore side at the left hand side of the figure, under a natural midline 11 and a mean waterline 12, to a riser 13 which is parallel to a vertical piling 14. In a preferred embodiment of the invention, the riser 13 is clamped to the piling 14.
Both the piling 14 and the riser 13 pass through a protective 30 cone 15 which rusts on the muslins 11. The protective cone 15 is not attached directly to the piling 14 or to the riser 13, but it is able to heave up and down with a freeze-thaw cycle while still providing protection to the riser 13 and the piling 14 from the ice.
~2Z~76~6 The piling 14 extends upwardly to horizontal joist member 16, which comprises preferably two parallel long-span joists. The riser 13 connects the pipeline 10 to a pipeline 17 which is supported by joist members 16 and conventional sliding shoe support cross members (not shown). Thermal expansion of the pipeline is accommodated with expansion offsets 18 contained within the open area between the joist members 16.
A sectional view of protective cone 15 is shown in Figure 2.
The outside shell of cone 15 and a reinforcing member 20 are preferably at an angle of about 45 degrees with respect to the bottom portion 19 of the cone which rests on the midline 11. The angle of the cone of about 45 degrees minimizes the lateral loads exerted by the ice on the piling and consequently minimizes the required piling diameter, thickness and embedment depth. Bottom portion 19 is further tied to reinforcing member 20 and the cone 15 by a reinforcing member 21.
In the Beau fort Sea on the worth Slope of Alaska, a shore approach begins in about 7 feet water depth and extends approximately one mile to a point 200 feet onshore. A one mile span elevates the pipeline by utilizing 240 feet joist members supported by 6 feet diameter steel piles. A riser extends below the midline to allow a cover of 3 feet over the top of the pipeline. Expansion in the elevated pipeline is allowed by expansion offsets every 480 feet.
The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described apparatus and method may be made within the scope of the appended claims without departing from the spirit of the invention.
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A structure for protecting a pipeline from forces exert-ed by ice as the pipeline is passed from offshore, under a soil line and then through an ice layer to onshore, comprising:
a series of substantially vertical pilings supporting substantially horizontal joist members;
a protective cone about each piling, the bottom of the protective cone resting on the soil line and the protective cone having an angle of about 45° and being essentially unconnected to the piling; and a riser, extending along one of the pilings, for accom-modating the transition of the pipeline located under the soil line to the pipeline supported by the joist members, wherein the riser extends within the protective cone and wherein the riser is essentially unconnected thereto.
a series of substantially vertical pilings supporting substantially horizontal joist members;
a protective cone about each piling, the bottom of the protective cone resting on the soil line and the protective cone having an angle of about 45° and being essentially unconnected to the piling; and a riser, extending along one of the pilings, for accom-modating the transition of the pipeline located under the soil line to the pipeline supported by the joist members, wherein the riser extends within the protective cone and wherein the riser is essentially unconnected thereto.
2. The structure of claim 1 wherein the pipeline is pro-vided with expansion offsets along the length of the joist members.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49484083A | 1983-05-16 | 1983-05-16 | |
| US494,840 | 1983-05-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1227646A true CA1227646A (en) | 1987-10-06 |
Family
ID=23966197
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000453434A Expired CA1227646A (en) | 1983-05-16 | 1984-05-03 | Protected pile and joist bridge shore approach |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1227646A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115125830A (en) * | 2022-06-30 | 2022-09-30 | 中国科学院西北生态环境资源研究院 | Rigidity balance structure for road and bridge transition section in permafrost region and construction method thereof |
-
1984
- 1984-05-03 CA CA000453434A patent/CA1227646A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115125830A (en) * | 2022-06-30 | 2022-09-30 | 中国科学院西北生态环境资源研究院 | Rigidity balance structure for road and bridge transition section in permafrost region and construction method thereof |
| CN115125830B (en) * | 2022-06-30 | 2023-04-28 | 中国科学院西北生态环境资源研究院 | Permafrost region road bridge transition section rigidity balance structure and construction method thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |