Underpinning - Revision history

Designing Buildings at 07:37, 10 September 2020

2020-09-10T07:37:20Z

← Older revision		Revision as of 07:37, 10 September 2020
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	* [http://www.labc.co.uk/news/underpinning-existing-foundations LABC].		* [http://www.labc.co.uk/news/underpinning-existing-foundations LABC].

−	[[Category:Construction_techniques]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Construction_techniques]]

Editor at 14:54, 1 May 2018

2018-05-01T14:54:36Z

← Older revision		Revision as of 14:54, 1 May 2018
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	Common reasons why underpinning may be necessary might include:		Common reasons why underpinning may be necessary might include:

−	* Subsidence (changes in the condition of the soil) or poor soil properties which may have caused the existing building’s foundations to move. This may be due to natural causes such as earthquake, flood, drought and so on.	+	* Subsidence (changes in the condition of the soil) or poor soil properties which may have caused the existing building’s foundations to move. This may be due to natural causes such as earthquake, flood, drought, and so on.
	* Additional building storeys, either above or below ground level, are to be added, meaning that existing foundations need to be strengthened so as to adequately support the modified load.		* Additional building storeys, either above or below ground level, are to be added, meaning that existing foundations need to be strengthened so as to adequately support the modified load.
	* Structures have been built nearby that alter the soil stability.		* Structures have been built nearby that alter the soil stability.
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	* Types of nails.		* Types of nails.
	* Underreaming.		* Underreaming.
		+	* Underwater foundations.
	* Vibro-compaction.		* Vibro-compaction.
	* Vibro-replacement.		* Vibro-replacement.

Editor at 12:15, 30 April 2018

2018-04-30T12:15:51Z

← Older revision		Revision as of 12:15, 30 April 2018
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	* Settlement.		* Settlement.
	* Shoring.		* Shoring.
		+	* Socket piles.
	* Soil nailing.		* Soil nailing.
	* Subsidence.		* Subsidence.

Editor at 13:32, 5 April 2018

2018-04-05T13:32:58Z

← Older revision		Revision as of 13:32, 5 April 2018
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	* Soil nailing.		* Soil nailing.
	* Subsidence.		* Subsidence.
		+	* Types of nails.
	* Underreaming.		* Underreaming.
	* Vibro-compaction.		* Vibro-compaction.

Designing Buildings at 07:53, 7 October 2017

2017-10-07T07:53:24Z

← Older revision		Revision as of 07:53, 7 October 2017
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	=== Related articles on Designing Buildings Wiki ===		=== Related articles on Designing Buildings Wiki ===

−	* Caisson.
−	* Cofferdam.
−	* Continuous flight auger piles.
	* Cracking and building movement.		* Cracking and building movement.
−	* External works.
	* Foundations.		* Foundations.
−	* Geothermal pile foundations.
	* Ground anchor.		* Ground anchor.
	* Ground heave.		* Ground heave.
−	* Groundworks.
	* Grouting in civil engineering.		* Grouting in civil engineering.
−	* Micropiles.
−	* Pad foundation.
−	* Pile foundations.
	* Preventing wall collapse.		* Preventing wall collapse.
−	* Raft foundation.
−	* Retaining walls.
−	* Screw pile foundations.
	* Settlement.		* Settlement.
	* Shoring.		* Shoring.
	* Soil nailing.		* Soil nailing.
	* Subsidence.		* Subsidence.
−	* Temporary works.
	* Underreaming.		* Underreaming.
	* Vibro-compaction.		* Vibro-compaction.
	* Vibro-replacement.		* Vibro-replacement.
		+	* Why do buildings crack? (DG 361).

	=== External references ===		=== External references ===

Editor at 15:16, 11 September 2017

2017-09-11T15:16:38Z

← Older revision		Revision as of 15:16, 11 September 2017
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	= Introduction =		= Introduction =

−	Where the foundations of an existing building or structure require strengthening and stabilising, a process of underpinning may be necessary. Excavated soil from beneath existing foundations is replaced with material, usually concrete, in a series of phases that increase the overall depth. This forms a new foundation beneath the existing one. To ensure that structural risks are mitigated against, there are design, methodology and safety procedures that must be adhered to.	+	Where the foundations of an existing building or structure require strengthening and stabilising, a process of underpinning may be necessary. Excavated soil from beneath existing foundations is replaced with material, usually concrete, in a series of phases that increase the overall depth. This forms a new foundation beneath the existing one.
		+
		+	To ensure that structural risks are mitigated against, there are design, methodology and safety procedures that must be adhered to.

	Common reasons why underpinning may be necessary might include:		Common reasons why underpinning may be necessary might include:
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	=== Mass concrete underpinning ===		=== Mass concrete underpinning ===

−	Due to its low cost and suitability for shallow depth underpinning, and heavy foundation loads, this is the most common method of underpinning. The ground below the existing building foundation is excavated in controlled stages (or pins). When strata suitable for bearing the weight of the building has been reached, the excavation is filled with concrete and left to cure before the next pin is excavated. Safe transfer of the building load to the new pin is achieved by ramming a dry sand cement packing mortar between new and old foundations. This technique cannot be adopted as solution for all situations, and to overcome difficulties such as groundwater, lose ground or fill, other techniques will be required.	+	Due to its low cost and suitability for shallow depth underpinning, and heavy foundation loads, this is the most common method of underpinning. The ground below the existing building foundation is excavated in controlled stages (or pins). When strata suitable for bearing the weight of the building has been reached, the excavation is filled with concrete and left to cure before the next pin is excavated.
		+
		+	Safe transfer of the building load to the new pin is achieved by ramming a dry sand cement packing mortar between new and old foundations. This technique cannot be adopted as solution for all situations, and to overcome difficulties such as groundwater, lose ground or fill, other techniques will be required.

	=== Beam and base underpinning ===		=== Beam and base underpinning ===
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	* Settlement.		* Settlement.
	* Shoring.		* Shoring.
		+	* Soil nailing.
	* Subsidence.		* Subsidence.
	* Temporary works.		* Temporary works.

Editor at 12:14, 21 July 2017

2017-07-21T12:14:04Z

← Older revision		Revision as of 12:14, 21 July 2017
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	* Screw pile foundations.		* Screw pile foundations.
	* Settlement.		* Settlement.
		+	* Shoring.
	* Subsidence.		* Subsidence.
	* Temporary works.		* Temporary works.

Editor at 14:56, 15 March 2017

2017-03-15T14:56:16Z

← Older revision		Revision as of 14:56, 15 March 2017
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	* Subsidence.		* Subsidence.
	* Temporary works.		* Temporary works.
		+	* Underreaming.
	* Vibro-compaction.		* Vibro-compaction.
	* Vibro-replacement.		* Vibro-replacement.

Editor at 12:07, 17 August 2016

2016-08-17T12:07:46Z

← Older revision		Revision as of 12:07, 17 August 2016
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	* Pad foundation.		* Pad foundation.
	* Pile foundations.		* Pile foundations.
		+	* Preventing wall collapse.
	* Raft foundation.		* Raft foundation.
	* Retaining walls.		* Retaining walls.

Editor at 11:46, 27 January 2016

2016-01-27T11:46:42Z

← Older revision		Revision as of 11:46, 27 January 2016
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	* Cofferdam.		* Cofferdam.
	* Continuous flight auger piles.		* Continuous flight auger piles.
		+	* Cracking and building movement.
	* External works.		* External works.
	* Foundations.		* Foundations.