Nelson River HVDC Transmission Line Foundations - Revision history

Rbernier at 01:52, 28 April 2016

2016-04-28T01:52:08Z

← Older revision		Revision as of 20:52, 27 April 2016
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	The Nelson River HVDC Transmission Lines, also known as Bipole's I & II, are a set of 895 km long double circuit transmission lines running parallel to each other and connect the Town of Gillam to the City of Winnipeg. ~~Combined, they~~ have a total of 3,918 guyed towers and 96 self-supporting angle towers. Foundation conditions varied significantly along the alignment of the transmission lines. ~~Some~~ of the foundation conditions encountered included ~~rock~~, deep muskeg, discontinuous permafrost, soft clays, boulder tills, and ground subject to seasonal frost ~~heave~~. The greatest challenges with respect to the design of the tower foundations involved the discontinuous permafrost and adfreeze forces.		The Nelson River HVDC Transmission Lines, also known as Bipole's I & II, are a set of 895 km long double circuit transmission lines running parallel to each other and connect the Town of Gillam in northern Manitoba to the City of Winnipeg in the south. The two combined have a total of 3,918 guyed towers and 96 self-supporting angle towers. Foundation conditions for the towers varied significantly along the route alignment for the transmission lines. Examples of the foundation conditions encountered included bedrock, deep muskeg, discontinuous permafrost, soft clays, boulder tills, and ground subject to seasonal frost heaving. The greatest challenges with respect to the design of the tower foundations involved the discontinuous permafrost and adfreeze forces.


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	[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]		[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]

	The southern ~~530 km~~ of the transmission corridor runs through the Interlake region of Manitoba ~~which~~ consists of level terrain ~~and~~ few ~~large swamps~~. ~~Limestone~~ bedrock varies from surface to in excess of 15 m. The predominant soil is glacial till with boulders, silts, and clays. Some sands and artesian flow conditions occur.		The southern portion of the transmission corridor is 530 km in length and runs through the Interlake region of Manitoba between Lake Winnipeg, Lake Manitoba and Lake Winnipegosis. The soil conditions in this area predominantly consists of flat level terrain with relatively few swampy areas. The limestone bedrock beneath the soils typically varies from being at the surface to in excess of 15 m down. The predominant soil in the area is glacial till with boulders, silts, and clays. Some sands and artesian flow conditions occur.

	The northern ~~365 km~~ of the transmission corridor is in the Precambrian ~~Shield which~~ is characterized by ~~widely varying~~ granite rock, deep ~~muskegs~~, and extensive peat lands. The soils vary from hard glacial till to very soft silty clays and intermittent submerged sand deposits. This section lies within ~~the~~ intermittent permafrost zone which is characterized by sporadic permafrost in the south near the north end of Lake Winnipeg to widespread permafrost in the north near Kettle Rapids and the Town of Gillam.		The northern portion of the transmission corridor is 365 km in length and runs through the Canadian shield (Precambrian bedrock). This terrain is characterized by rugged granite rock, deep muskeg, and extensive peat lands. The soils vary from hard glacial till to very soft silty clays and intermittent submerged sand deposits. This section of the transmission corridor lies within an intermittent permafrost zone, which is characterized by sporadic permafrost in the south near the north end of Lake Winnipeg to widespread permafrost in the north near Kettle Rapids and the Town of Gillam. The ground conditions can vary so significantly that within a single tower it is not unusual to have four anchors of a guyed tower within four different sub-surface conditions.
	The ground conditions can vary so significantly that within a single tower it is not unusual to have four anchors of a guyed tower within four different sub-surface conditions.

	==When==		==When==
	*Concept, terrain analysis & route selection - 1966		*Concept, terrain analysis & route selection - 1966
	*Anchor tests – 1966 - 1968		*Anchor tests – 1966 to 1968
	*Surveys and geotechnical – 1967 to 1969		*Surveys and geotechnical – 1967 to 1969
	*Design – 1967 to 1969		*Design – 1967 to 1969
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	==Research==		==Research==

	The size and importance of the project justified ~~more than the usual~~ amount of research, principally related to permafrost and adfreeze forces.		The relative size and importance of the HVDC project justified a meaningful amount of research going into its design, principally related to permafrost and adfreeze forces.

	Extensive laboratory testing, analytical studies, and literature reviews were carried out to obtain basic data on the engineering properties of thawed permafrost soils, rates of regression of the permafrost table and the nature and extent of settlements resulting from thawing. Close liaison was maintained with the National Research Council of Canada and the U. S. Army Material Command’s Cold Regions Research and Engineering Laboratory. Pioneering work in the U.S.S.R. was also used.		Extensive laboratory testing, analytical studies, and literature reviews were carried out to obtain basic data on the engineering properties of thawed permafrost soils, rates of regression of the permafrost table, and the nature and extent of settlements resulting from thawing. Close liaison was maintained with the National Research Council of Canada and the U. S. Army Material Command’s Cold Regions Research and Engineering Laboratory. Pioneering work from the U.S.S.R. was also used.

	~~Extensive~~ anchor ~~test programs were~~ carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested ~~by Manitoba Hydro~~ included grouted, belled, screw-in, plate and Malone types. ~~Teshmont Consultants conducted, for~~ Atomic Energy of Canada ~~Limited~~, additional anchor ~~test~~ programs including tests on overburden drilled anchors, driven pile anchors ~~and~~ a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. ~~Twenty~~ anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.		Part of the research and design process included an extensive anchor testing program which was carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested included grouted, belled, screw-in, plate, and Malone types. On behalf of Atomic Energy of Canada, Teshmont Consultants conducted additional anchor testing programs including tests on overburden drilled anchors and driven pile anchors. In addition they conducted a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. In total twenty anchors were installed in the permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted to within an acceptable degree of accuracy.

	[[File:Tower Cross Section.jpg\|thumb\|Figure 2: Tower Cross Sections ]]		[[File:Tower Cross Section.jpg\|thumb\|Figure 2: Tower Cross Sections ]]
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	==Permafrost==		==Permafrost==

	~~The permafrost occurs~~ in areas as small as a few square ~~metres~~ to as large as several acres. The depth of the permafrost varied from less than 3 m to 30 m ~~or more~~, in no set pattern. The frozen soils are silty clays containing ice inclusions and lenses up to 300 mm thick. Ground temperature in the upper layers is -1C to 0C. Studies indicated the ~~ground~~ will not remain frozen. In the frozen state the soils have substantial pullout resistance. In the thawed state the soil is transformed into a fluid structure with a drastic reduction in strength and consolidation results in large settlements.		Permafrost can occur in areas as small as a few square meters to as large as several acres. The depth of the permafrost varied from less than 3 m deep to more than 30 m, in no particular set pattern. The frozen soils contained within permafrost are typically silty clays containing ice inclusions and lenses up to 300 mm thick. Ground temperature in the upper layers is -1C to 0C. Studies indicated the impacted areas will not remain frozen. In the frozen state the soils have substantial pullout resistance. However, in the thawed state the soil is transformed into a fluid like structure with a drastic reduction in strength, and consolidation results in large settlements.

	The rate of regression of the permafrost table was estimated based on one dimensional heat transfer. Five idealized soil profiles were analyzed.		The rate of regression of the permafrost table was estimated based on one dimensional heat transfer. Five idealized soil profiles were analyzed.
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	==Frost Forces==		==Frost Forces==

	Frost heave and adfreeze forces were computed by an empirical approach described by N. A. Tsytovich ~~and~~ field and laboratory testing by Dalmatov and Vyalov. The average force of 96 kPa over 1.8 m was compared to observations by Crory in Alaska and the U.S.S.R. permafrost design manual. Reducing the forces by granular backfill or providing a slip surface was rejected due to high water ~~table~~ and ~~difficult~~ maintenance.		Frost heave and adfreeze forces were computed by an empirical approach described by N. A. Tsytovich with field and laboratory testing done by Dalmatov and Vyalov. The average force of 96 kPa over 1.8 m was compared to observations by Crory in Alaska and the U.S.S.R. permafrost design manual. Reducing the forces by granular backfill or providing a slip surface was rejected due to high water tables and maintenance difficulty.

	==Designs==		==Designs==
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	The legs of self supporting towers and the masts of the guyed towers are supported on spread type footings consisting of a galvanized steel framework on a treated timber pad. For the 190 km section south from Gypsumville the masts of the guyed towers are supported on 1.07 m by 3.35 m deep concrete caissons.		The legs of self supporting towers and the masts of the guyed towers are supported on spread type footings consisting of a galvanized steel framework on a treated timber pad. For the 190 km section south from Gypsumville the masts of the guyed towers are supported on 1.07 m by 3.35 m deep concrete caissons.

	The 150 mm overburden drilled type of anchor was chosen as the most versatile and economic system. The maximum drilling depth was initially 15 m~~. In the~~ soft clays and permafrost ~~400 – 450~~ mm diameter anchors were installed in 1969. This system was slow and costly and drilling equipment was improved to advance the 150mm system to 24.4m.		The 150 mm overburden drilled type of anchor was chosen as the most versatile and economic system. The maximum drilling depth was initially 15 m however, in soft clays and permafrost 400–450 mm diameter anchors were installed utilized (1969). This system was slow and costly and drilling equipment was improved to advance the 150mm system to 24.4m.

	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.
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	In the 1970’s ID Engineering Company, one of the founding members of Teshmont, supported research into adfreeze forces at the University of Manitoba. A 2.4 m steel tank was fitting with refrigeration equipment to freeze soils with embedded structural members and measure forces.		In the 1970’s ID Engineering Company, one of the founding members of Teshmont, supported research into adfreeze forces at the University of Manitoba. A 2.4 m steel tank was fitting with refrigeration equipment to freeze soils with embedded structural members and measure forces.

	Shortly after construction a number of mast support quadruped legs were bent and the top cap was torn at the corner weld by the block of frozen soil rising within the sloping legs. The soil was replaced by a Styrofoam block.		Shortly after construction, a number of mast support quadruped legs were bent and the top cap was torn at the corner weld by the block of frozen soil rising within the sloping legs. The soil was replaced by a Styrofoam block.

	Also within a few years a number of spread footings experienced excessive settlement that was corrected during maintenance.		Also, within a few years a number of spread footings experienced excessive settlement that was corrected during maintenance.

	==Influence==		==Influence==
	The Nelson River Transmission ~~Line is~~ an innovative, successful facility that brings 75% of Manitoba power to southern Manitoba and for export.		The Nelson River Transmission Lines are an innovative, successful facility that brings 75% of Manitoba power to southern Manitoba and for export.

	==Key players==		==Key players==

Rbernier at 17:15, 27 April 2016

2016-04-27T17:15:44Z

← Older revision		Revision as of 12:15, 27 April 2016
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	The Nelson River HVDC Transmission ~~Line (~~Bipole I & II~~) is~~ a 895 km long double circuit transmission ~~line (two~~ parallel ~~power lines) from~~ Gillam to Winnipeg. ~~It has~~ 3,918 guyed towers and 96 self-supporting ~~major~~ angle towers. Foundation conditions varied along the alignment of the transmission ~~line~~. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces ~~were the greatest challenge for the tower foundations~~.		The Nelson River HVDC Transmission Lines, also known as Bipole's I & II, are a set of 895 km long double circuit transmission lines running parallel to each other and connect the Town of Gillam to the City of Winnipeg. Combined, they have a total of 3,918 guyed towers and 96 self-supporting angle towers. Foundation conditions varied significantly along the alignment of the transmission lines. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills, and ground subject to seasonal frost heave. The greatest challenges with respect to the design of the tower foundations involved the discontinuous permafrost and adfreeze forces.


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	[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]		[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]

	The southern 530 km of transmission ~~line~~ through the Interlake ~~are~~ of Manitoba ~~has~~ level terrain ~~containing~~ few large swamps. Limestone bedrock varies from surface to in excess of 15 m. The predominant soil is glacial till with boulders, ~~and~~ silts and clays. Some sands and artesian flow conditions occur.		The southern 530 km of the transmission corridor runs through the Interlake region of Manitoba which consists of level terrain and few large swamps. Limestone bedrock varies from surface to in excess of 15 m. The predominant soil is glacial till with boulders, silts, and clays. Some sands and artesian flow conditions occur.

	The northern 365 km of the transmission ~~line~~ is in the Precambrian Shield characterized by widely varying granite rock, deep muskegs, and extensive peat lands. The soils vary from hard glacial till to very soft silty clays and intermittent submerged sand deposits. This section lies within the intermittent permafrost zone~~: with~~ sporadic permafrost in the south ~~starting~~ near the north end of Lake Winnipeg; to widespread in the north near Kettle Rapids and Gillam.		The northern 365 km of the transmission corridor is in the Precambrian Shield which is characterized by widely varying granite rock, deep muskegs, and extensive peat lands. The soils vary from hard glacial till to very soft silty clays and intermittent submerged sand deposits. This section lies within the intermittent permafrost zone which is characterized by sporadic permafrost in the south near the north end of Lake Winnipeg to widespread permafrost in the north near Kettle Rapids and the Town of Gillam.
			The ground conditions can vary so significantly that within a single tower it is not unusual to have four anchors of a guyed tower within four different sub-surface conditions.
	The ground conditions within a tower ~~vary considerably and~~ it is not unusual to have four anchors of ~~the~~ guyed ~~towers in~~ different sub-surface conditions.

	==When==		==When==
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	==Research==		==Research==

	The size and importance of the project justified more than the usual amount of research principally related to permafrost and adfreeze forces.		The size and importance of the project justified more than the usual amount of research, principally related to permafrost and adfreeze forces.

	Extensive laboratory testing, analytical studies, and literature reviews were carried out to obtain basic data on the engineering properties of thawed permafrost soils, rates of regression of the permafrost table and the nature and extent of settlements resulting from thawing. Close liaison was maintained with the National Research Council of Canada and the U. S. Army Material Command’s Cold Regions Research and Engineering Laboratory. Pioneering work in the U.S.S.R. was also used.		Extensive laboratory testing, analytical studies, and literature reviews were carried out to obtain basic data on the engineering properties of thawed permafrost soils, rates of regression of the permafrost table and the nature and extent of settlements resulting from thawing. Close liaison was maintained with the National Research Council of Canada and the U. S. Army Material Command’s Cold Regions Research and Engineering Laboratory. Pioneering work in the U.S.S.R. was also used.

Rbernier at 03:27, 27 April 2016

2016-04-27T03:27:31Z

← Older revision		Revision as of 22:27, 26 April 2016
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	==Where==		==Where==
			[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]

	The southern 530 km of transmission line through the Interlake are of Manitoba has level terrain containing few large swamps. Limestone bedrock varies from surface to in excess of 15 m. The predominant soil is glacial till with boulders, and silts and clays. Some sands and artesian flow conditions occur.		The southern 530 km of transmission line through the Interlake are of Manitoba has level terrain containing few large swamps. Limestone bedrock varies from surface to in excess of 15 m. The predominant soil is glacial till with boulders, and silts and clays. Some sands and artesian flow conditions occur.

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	The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.		The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.

	~~[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]~~

	==When==		==When==
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	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.

	[[File:Foundation Cross Section.jpg~~\|thumb\|center~~\|Figure 3: Foundation Cross Section~~]] [[~~File:Anchor Cross Section.jpg~~\|thumb\|center~~\|Figure 4: Anchor Cross Section]]		<gallery heights=400px widths=400px>
			File:Foundation Cross Section.jpg\|Figure 3: Foundation Cross Section
			File:OB Drill.jpg\|Photo 1: OB Drill
			File:Anchor Cross Section.jpg\|Figure 4: Anchor Cross Section
			File:Testing Guy Anchors at Structure.jpg\|Photo 2: Testing Guy Anchors at Structures
			</gallery>

	~~[[File:OB Drill.jpg\|thumb\|center\|Photo 1: OB Drill]] [[File:Testing Guy Anchors at Structure.jpg\|thumb\|center\|Photo 2: Testing Guy Anchors at Structures]]~~

	==Stories==		==Stories==

Rbernier at 01:48, 27 April 2016

2016-04-27T01:48:53Z

← Older revision		Revision as of 20:48, 26 April 2016
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	The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.		The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.

	[[File:BiPole Routing.jpg\|thumb~~\|center\|upright=2.0~~\|Figure 1: BiPole I & II Routing]]		[[File:BiPole Routing.jpg\|thumb\|Figure 1: BiPole I & II Routing]]

	==When==		==When==
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	Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.		Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.

	[[File:Tower Cross Section.jpg\|thumb~~\|center\|upright=2.0~~\|Figure 2: Tower Cross Sections ]]		[[File:Tower Cross Section.jpg\|thumb\|Figure 2: Tower Cross Sections ]]

	==Permafrost==		==Permafrost==
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	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.

	[[File:Foundation Cross Section.jpg\|thumb\|center\|~~upright=2~~.0\|Figure 3: ~~Foundation~~ Cross Section]]		[[File:Foundation Cross Section.jpg\|thumb\|center\|Figure 3: Foundation Cross Section]] [[File:Anchor Cross Section.jpg\|thumb\|center\|Figure 4: Anchor Cross Section]]

	~~[[File:Anchor Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 4: Anchor Cross Section]]~~		[[File:OB Drill.jpg\|thumb\|center\|Photo 1: OB Drill]] [[File:Testing Guy Anchors at Structure.jpg\|thumb\|center\|Photo 2: Testing Guy Anchors at Structures]]

	[[File:OB Drill.jpg\|thumb\|center~~\|upright=2.0~~\|Photo 1: OB Drill]]

	[[File:Testing Guy Anchors at Structure.jpg\|thumb\|center~~\|upright=2.0~~\|Photo 2: Testing Guy Anchors at Structures]]

	==Stories==		==Stories==

Rbernier at 01:44, 27 April 2016

2016-04-27T01:44:57Z

← Older revision		Revision as of 20:44, 26 April 2016
Line 1:		Line 1:
	The Nelson River HVDC Transmission Line (Bipole I & II) is a 895 km long double circuit transmission line (two parallel power lines) from Gillam to Winnipeg. It has 3,918 guyed towers and 96 self-supporting major angle towers. Foundation conditions varied along the alignment of the transmission line. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces were the greatest challenge for the tower foundations.		The Nelson River HVDC Transmission Line (Bipole I & II) is a 895 km long double circuit transmission line (two parallel power lines) from Gillam to Winnipeg. It has 3,918 guyed towers and 96 self-supporting major angle towers. Foundation conditions varied along the alignment of the transmission line. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces were the greatest challenge for the tower foundations.


	==Where==		==Where==
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	The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.		The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.

	[[:File:BiPole Routing.jpg\|thumb\|center\|upright=2.0\|Figure 1: BiPole I & II Routing]]		[[File:BiPole Routing.jpg\|thumb\|center\|upright=2.0\|Figure 1: BiPole I & II Routing]]

	==When==		==When==
Line 25:		Line 26:
	Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.		Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.

	[[:File:Tower Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 2: Tower Cross Sections ]]		[[File:Tower Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 2: Tower Cross Sections ]]

	==Permafrost==		==Permafrost==
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	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.

	[[:File:Foundation Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 3: Foundation Cross Section]]		[[File:Foundation Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 3: Foundation Cross Section]]

	[[:File:Anchor Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 4: Anchor Cross Section]]		[[File:Anchor Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 4: Anchor Cross Section]]

	[[:File:OB Drill.jpg\|thumb\|center\|upright=2.0\|Photo 1: OB Drill]]		[[File:OB Drill.jpg\|thumb\|center\|upright=2.0\|Photo 1: OB Drill]]

	[[:File:Testing Guy Anchors at Structure.jpg\|thumb\|center\|upright=2.0\|Photo 2: Testing Guy Anchors at Structures]]		[[File:Testing Guy Anchors at Structure.jpg\|thumb\|center\|upright=2.0\|Photo 2: Testing Guy Anchors at Structures]]

	==Stories==		==Stories==

Rbernier at 01:42, 27 April 2016

2016-04-27T01:42:30Z

← Older revision		Revision as of 20:42, 26 April 2016
Line 8:		Line 8:
	The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.		The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.

	[[:File:BiPole Routing.jpg]]		[[:File:BiPole Routing.jpg\|thumb\|center\|upright=2.0\|Figure 1: BiPole I & II Routing]]

	==When==		==When==
Line 25:		Line 25:
	Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.		Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.

	[[:File:Tower Cross Section.jpg]]		[[:File:Tower Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 2: Tower Cross Sections ]]

	==Permafrost==		==Permafrost==
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	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.

	[[:File:Foundation Cross Section.jpg]]		[[:File:Foundation Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 3: Foundation Cross Section]]

	[[:File:Anchor Cross Section.jpg]]		[[:File:Anchor Cross Section.jpg\|thumb\|center\|upright=2.0\|Figure 4: Anchor Cross Section]]

	[[:File:OB Drill.jpg]]		[[:File:OB Drill.jpg\|thumb\|center\|upright=2.0\|Photo 1: OB Drill]]

	[[:File:Testing Guy Anchors at Structure.jpg]]		[[:File:Testing Guy Anchors at Structure.jpg\|thumb\|center\|upright=2.0\|Photo 2: Testing Guy Anchors at Structures]]

	==Stories==		==Stories==

Rbernier at 01:35, 27 April 2016

2016-04-27T01:35:45Z

← Older revision		Revision as of 20:35, 26 April 2016
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	~~==Overview==~~

	The Nelson River HVDC Transmission Line (Bipole I & II) is a 895 km long double circuit transmission line (two parallel power lines) from Gillam to Winnipeg. It has 3,918 guyed towers and 96 self-supporting major angle towers. Foundation conditions varied along the alignment of the transmission line. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces were the greatest challenge for the tower foundations.		The Nelson River HVDC Transmission Line (Bipole I & II) is a 895 km long double circuit transmission line (two parallel power lines) from Gillam to Winnipeg. It has 3,918 guyed towers and 96 self-supporting major angle towers. Foundation conditions varied along the alignment of the transmission line. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces were the greatest challenge for the tower foundations.

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	The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.		The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.

			[[:File:BiPole Routing.jpg]]

	==When==		==When==
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	Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.		Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.

			[[:File:Tower Cross Section.jpg]]

	==Permafrost==		==Permafrost==
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	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.

			[[:File:Foundation Cross Section.jpg]]

			[[:File:Anchor Cross Section.jpg]]

			[[:File:OB Drill.jpg]]

			[[:File:Testing Guy Anchors at Structure.jpg]]

	==Stories==		==Stories==
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	==Key players==		==Key players==

	Client – ~~AECl~~/Manitoba Hydro:		Client – AECL/Manitoba Hydro:
	*Harry Smith P. Eng., AECL		*Harry Smith P. Eng., AECL
	*Gordon E. McLure P. Eng, Manitoba Hydro		*Gordon E. McLure P. Eng, Manitoba Hydro

Aletts at 00:30, 20 May 2014

2014-05-20T00:30:59Z

← Older revision		Revision as of 19:30, 19 May 2014
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	==Where==		==Where==
	The southern ~~530k~~ through the Interlake has level terrain containing few large swamps. Limestone bedrock varies from surface to in excess of ~~15m~~. The predominant soil is glacial till with boulders, and silts and clays. Some sands and artesian flow conditions occur.		The southern 530 km of transmission line through the Interlake are of Manitoba has level terrain containing few large swamps. Limestone bedrock varies from surface to in excess of 15 m. The predominant soil is glacial till with boulders, and silts and clays. Some sands and artesian flow conditions occur.

	The northern ~~365k~~ is in the Precambrian Shield characterized by widely varying granite rock, deep muskegs, and extensive peat lands. The soils vary from hard glacial till to very soft silty clays and intermittent submerged sand deposits. This section lies within the intermittent permafrost zone: with sporadic permafrost in the south starting near the north end of Lake Winnipeg; to widespread in the north near Kettle Rapids and Gillam.		The northern 365 km of the transmission line is in the Precambrian Shield characterized by widely varying granite rock, deep muskegs, and extensive peat lands. The soils vary from hard glacial till to very soft silty clays and intermittent submerged sand deposits. This section lies within the intermittent permafrost zone: with sporadic permafrost in the south starting near the north end of Lake Winnipeg; to widespread in the north near Kettle Rapids and Gillam.

	The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.		The ground conditions within a tower vary considerably and it is not unusual to have four anchors of the guyed towers in different sub-surface conditions.
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	Extensive laboratory testing, analytical studies, and literature reviews were carried out to obtain basic data on the engineering properties of thawed permafrost soils, rates of regression of the permafrost table and the nature and extent of settlements resulting from thawing. Close liaison was maintained with the National Research Council of Canada and the U. S. Army Material Command’s Cold Regions Research and Engineering Laboratory. Pioneering work in the U.S.S.R. was also used.		Extensive laboratory testing, analytical studies, and literature reviews were carried out to obtain basic data on the engineering properties of thawed permafrost soils, rates of regression of the permafrost table and the nature and extent of settlements resulting from thawing. Close liaison was maintained with the National Research Council of Canada and the U. S. Army Material Command’s Cold Regions Research and Engineering Laboratory. Pioneering work in the U.S.S.R. was also used.

	Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for ~~the~~ Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.		Extensive anchor test programs were carried out by Manitoba Hydro at several sites representing various soil conditions. The anchors tested by Manitoba Hydro included grouted, belled, screw-in, plate and Malone types. Teshmont Consultants conducted, for Atomic Energy of Canada Limited, additional anchor test programs including tests on overburden drilled anchors, driven pile anchors and a series of detailed field tests to determine the behavior of straight shaft and belled cast-in-place concrete anchors in thawed permafrost affected ground. Twenty anchors were installed in permafrost and the ground was thawed by means of rod type electric heaters. The anchors were then tested to failure. The behavior of the anchors under anticipated thawing conditions was predicted within an acceptable degree of accuracy.

	==Permafrost==		==Permafrost==

	The permafrost occurs in ~~area from~~ a few square metres to several acres ~~and in~~ depth from less than 3m to ~~30m~~ or more, in no set pattern. The frozen soils are silty clays containing ice inclusions and lenses up to ~~300mm~~ thick. Ground temperature in the upper layers is -1C to 0C. Studies indicated the ground will not remain frozen. In the frozen state the soils have substantial pullout resistance. In the thawed state the soil is transformed into a fluid structure with a drastic reduction in strength and consolidation results in large settlements.		The permafrost occurs in areas as small as a few square metres to as large as several acres. The depth of the permafrost varied from less than 3 m to 30 m or more, in no set pattern. The frozen soils are silty clays containing ice inclusions and lenses up to 300 mm thick. Ground temperature in the upper layers is -1C to 0C. Studies indicated the ground will not remain frozen. In the frozen state the soils have substantial pullout resistance. In the thawed state the soil is transformed into a fluid structure with a drastic reduction in strength and consolidation results in large settlements.

	The rate of regression of the permafrost table was estimated based on one dimensional heat transfer. Five idealized soil profiles were analyzed.		The rate of regression of the permafrost table was estimated based on one dimensional heat transfer. Five idealized soil profiles were analyzed.
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	==Frost Forces==		==Frost Forces==

	Frost heave and adfreeze forces were computed by an empirical approach described by N. A. Tsytovich and field and laboratory testing by Dalmatov and Vyalov. The average force of 96 kPa over 1.8m was compared to observations by Crory in Alaska and the U.S.S.R. permafrost design manual.		Frost heave and adfreeze forces were computed by an empirical approach described by N. A. Tsytovich and field and laboratory testing by Dalmatov and Vyalov. The average force of 96 kPa over 1.8 m was compared to observations by Crory in Alaska and the U.S.S.R. permafrost design manual. Reducing the forces by granular backfill or providing a slip surface was rejected due to high water table and difficult maintenance.
	Reducing the forces by granular backfill or providing a slip surface was rejected due to high water table and difficult maintenance.

	==Designs==		==Designs==

	The legs of self supporting towers and the masts of the guyed towers are supported on spread type footings consisting of a galvanized steel framework on a treated timber pad. For the ~~190k~~ section south from Gypsumville the masts of the guyed towers are supported on 1.~~07m~~ by 3.~~35m~~ deep concrete caissons.		The legs of self supporting towers and the masts of the guyed towers are supported on spread type footings consisting of a galvanized steel framework on a treated timber pad. For the 190 km section south from Gypsumville the masts of the guyed towers are supported on 1.07 m by 3.35 m deep concrete caissons.

	The ~~150mm~~ overburden drilled type of anchor was chosen as the most versatile and economic system. The maximum drilling depth was initially ~~15m~~. In the soft clays and permafrost 400 – ~~450mm~~ diameter anchors were installed in 1969. This system was slow and costly and drilling equipment was improved to advance the 150mm system to 24.4m.		The 150 mm overburden drilled type of anchor was chosen as the most versatile and economic system. The maximum drilling depth was initially 15 m. In the soft clays and permafrost 400 – 450 mm diameter anchors were installed in 1969. This system was slow and costly and drilling equipment was improved to advance the 150mm system to 24.4m.

	Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.		Approximately 8000 anchors were tested and 150 required corrective measures consisting of an anchor of greater length or a second anchor with a yolk.
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	==Stories==		==Stories==

	In the 1970’s ID Engineering Company, one of the founding members of Teshmont, supported research into adfreeze forces at the University of Manitoba. A 2.4m steel tank was fitting with refrigeration equipment to freeze soils with embedded structural members and measure forces.		In the 1970’s ID Engineering Company, one of the founding members of Teshmont, supported research into adfreeze forces at the University of Manitoba. A 2.4 m steel tank was fitting with refrigeration equipment to freeze soils with embedded structural members and measure forces.

	Shortly after construction a number of mast support quadruped legs were bent and the top cap was torn at the corner weld by the block of frozen soil rising within the sloping legs. The soil was replaced by a Styrofoam block.		Shortly after construction a number of mast support quadruped legs were bent and the top cap was torn at the corner weld by the block of frozen soil rising within the sloping legs. The soil was replaced by a Styrofoam block.

Aletts: /* Overview */

2014-05-20T00:23:10Z

Overview

← Older revision		Revision as of 19:23, 19 May 2014
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	==Overview==		==Overview==

	The ~~895k~~ long double circuit transmission line (two parallel power lines) from Gillam to Winnipeg has 3,918 guyed towers and 96 self-supporting major angle towers. Foundation conditions ~~were~~ rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces were the greatest challenge.		The Nelson River HVDC Transmission Line (Bipole I & II) is a 895 km long double circuit transmission line (two parallel power lines) from Gillam to Winnipeg. It has 3,918 guyed towers and 96 self-supporting major angle towers. Foundation conditions varied along the alignment of the transmission line. Some of the foundation conditions encountered included rock, deep muskeg, discontinuous permafrost, soft clays, boulder tills and ground subject to seasonal frost heave. The discontinuous permafrost and adfreeze forces were the greatest challenge for the tower foundations.

	==Where==		==Where==

Aletts at 00:13, 20 May 2014

2014-05-20T00:13:36Z

← Older revision		Revision as of 19:13, 19 May 2014
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	==When==		==When==
	Concept, ~~Terrain~~ analysis, route selection 1966		*Concept, terrain analysis & route selection - 1966
			*Anchor tests – 1966 - 1968
	Anchor tests – 1966 - 1968		*Surveys and geotechnical – 1967 to 1969
			*Design – 1967 to 1969
	Surveys and geotechnical – 1967 to 1969		*Construction - 1968 to 1970

	Design – 1967 to 1969

	Construction - 1968 to 1970

	==Research==		==Research==
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	Client – AECl/Manitoba Hydro:		Client – AECl/Manitoba Hydro:
	Harry Smith P. Eng., AECL		*Harry Smith P. Eng., AECL
	Gordon E. McLure P. Eng, Manitoba Hydro		*Gordon E. McLure P. Eng, Manitoba Hydro

	Designers/Engineers/Geoscientists		Designers/Engineers/Geoscientists:
	Ilmar Reinart P. Eng., Teshmont Consultants Ltd.		*Ilmar Reinart P. Eng., Teshmont Consultants Ltd.
	A. Staudz P. Eng., Teshmont Consultants. Ltd.		*A. Staudz P. Eng., Teshmont Consultants. Ltd.
	Larry Hurwitz P. Eng., Independent Testlabs Ltd.		*Larry Hurwitz P. Eng., Independent Testlabs Ltd.
	Jack Mollard P. Eng., J. D. Mollard & Associates		*Jack Mollard P. Eng., J. D. Mollard & Associates

	==References==		==References==

	Nelson River Transmission Line - Foundation Design Aspects. I. Reinart P. Eng. Project Engineer – Foundations, Teshmont Consultants Ltd. Manitoba Power Conference EHV – DC Winnipeg. Canada. June 7-10, 1971		Nelson River Transmission Line - Foundation Design Aspects. I. Reinart P. Eng. Project Engineer – Foundations, Teshmont Consultants Ltd. Manitoba Power Conference EHV – DC Winnipeg. Canada. June 7-10, 1971