Sinkholes - Revision history

Editor at 18:58, 20 September 2021

2021-09-20T18:58:08Z

← Older revision		Revision as of 18:58, 20 September 2021
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	* Grouting in civil engineering.		* Grouting in civil engineering.
	* Gully.		* Gully.
		+	* Inflow.
	* Institution of Civil Engineers.		* Institution of Civil Engineers.
	* Pumps and dewatering equipment.		* Pumps and dewatering equipment.

Editor at 15:13, 21 May 2021

2021-05-21T15:13:19Z

← Older revision		Revision as of 15:13, 21 May 2021
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	* Groundwater control in urban areas.		* Groundwater control in urban areas.
	* Grouting in civil engineering.		* Grouting in civil engineering.
		+	* Gully.
	* Institution of Civil Engineers.		* Institution of Civil Engineers.
	* Pumps and dewatering equipment.		* Pumps and dewatering equipment.

Editor at 14:28, 21 May 2021

2021-05-21T14:28:20Z

← Older revision		Revision as of 14:28, 21 May 2021
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	Sinkholes can also form above cavities that occur as a result of other processes such as the emptying of liquid lava inside a lava flow (a Thurston Tube), ice wedging in cold climates, or large-scale movement of rock leaving chasms, known as ‘guls’.		Sinkholes can also form above cavities that occur as a result of other processes such as the emptying of liquid lava inside a lava flow (a Thurston Tube), ice wedging in cold climates, or large-scale movement of rock leaving chasms, known as ‘guls’.

−	In the UK, there has been a long history of mining and water abstraction, which in some areas has left a legacy of man-made cavities. The term sinkhole in the UK, is often extended to cover the collapse of ground into such man-made features.	+	In the UK, there has been a long history of mining and water abstraction, which in some areas has left a legacy of man-made cavities. The term sinkhole in the UK is often extended to cover the collapse of ground into such man-made features.

	Suffosion and dropout sinkholes form entirely within the soil profile above the cavity with infiltrating water washing soil down into open discontinuities in the rockhead. Dissolution, collapse and caprock sinkholes are all dependent on solution and rock mechanics processes that generally occur over geological timescales related to the solubility and other properties of the country rockmass.		Suffosion and dropout sinkholes form entirely within the soil profile above the cavity with infiltrating water washing soil down into open discontinuities in the rockhead. Dissolution, collapse and caprock sinkholes are all dependent on solution and rock mechanics processes that generally occur over geological timescales related to the solubility and other properties of the country rockmass.
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	The collapse of ground above cavities and the formation of sinkholes is almost always the result of concentrated flow of water. This might arise as a result of rainfall runoff, the construction of a soakaway, or as a result of fractured water or waste pipes or changes in natural drainage such as drawing down of the water table for major civil or mining works. Tony Waltham, went so far as to title his recent Geological Society Glossop Medal presentation, ‘Control the Drainage: The Gospel According to Sinkholes’.		The collapse of ground above cavities and the formation of sinkholes is almost always the result of concentrated flow of water. This might arise as a result of rainfall runoff, the construction of a soakaway, or as a result of fractured water or waste pipes or changes in natural drainage such as drawing down of the water table for major civil or mining works. Tony Waltham, went so far as to title his recent Geological Society Glossop Medal presentation, ‘Control the Drainage: The Gospel According to Sinkholes’.

−	On rare occasions, cavities have collapsed as a result of the failure of man-made caps, with disastrous consequences. In such cases, it ha been found that the cap was simply made by placing railway sleepers over a narrow shaft entrance, and these have rotted with time, or masonry which has been buried, forgotten and not maintained.	+	On rare occasions, cavities have collapsed as a result of the failure of man-made caps, with disastrous consequences. In such cases, it has been found that the cap was simply made by placing railway sleepers over a narrow shaft entrance, and these have rotted with time, or masonry which has been buried, forgotten and not maintained.

	= What can civil engineers do to prevent/avoid sinkholes? =		= What can civil engineers do to prevent/avoid sinkholes? =

Designing Buildings at 07:09, 5 November 2020

2020-11-05T07:09:43Z

← Older revision		Revision as of 07:09, 5 November 2020
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	* Why do buildings crack? (DG 361).		* Why do buildings crack? (DG 361).

−	[[Category:~~Research_/_Innovation~~]] [[Category:DCN_Research,_Development_and_Innovation]] [[Category:Health_and_safety_/_CDM]]	+	[[Category:DCN_Commentary]] [[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Research,_Development_and_Innovation]] [[Category:Research_/_Innovation]] [[Category:Health_and_safety_/_CDM]]

Editor at 16:07, 29 March 2019

2019-03-29T16:07:56Z

← Older revision		Revision as of 16:07, 29 March 2019
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	--[[User:The_Institution_of_Civil_Engineers\|The Institution of Civil Engineers]]		--[[User:The_Institution_of_Civil_Engineers\|The Institution of Civil Engineers]]

−	~~= Find out more =~~	+	= Related articles on Designing Buildings Wiki =
−		+
−	=== Related articles on Designing Buildings Wiki ===	+

	* Cracking and building movement.		* Cracking and building movement.
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	* Spalling.		* Spalling.
	* Subsidence.		* Subsidence.
		+	* Sump pump.
	* Underpinning.		* Underpinning.
	* Why do buildings crack? (DG 361).		* Why do buildings crack? (DG 361).

−	[[Category:Research_/_Innovation]] [[Category:Health_and_safety_/_CDM]]	+	[[Category:Research_/_Innovation]] [[Category:DCN_Research,_Development_and_Innovation]] [[Category:Health_and_safety_/_CDM]]

Designing Buildings at 07:51, 7 October 2017

2017-10-07T07:51:48Z

← Older revision		Revision as of 07:51, 7 October 2017
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	* Subsidence.		* Subsidence.
	* Underpinning.		* Underpinning.
		+	* Why do buildings crack? (DG 361).

	[[Category:Research_/_Innovation]] [[Category:Health_and_safety_/_CDM]]		[[Category:Research_/_Innovation]] [[Category:Health_and_safety_/_CDM]]

Editor at 11:50, 10 August 2016

2016-08-10T11:50:38Z

← Older revision		Revision as of 11:50, 10 August 2016
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	* Grouting in civil engineering.		* Grouting in civil engineering.
	* Institution of Civil Engineers.		* Institution of Civil Engineers.
		+	* Pumps and dewatering equipment.
	* Remedial works.		* Remedial works.
	* Soil survey.		* Soil survey.

Editor at 13:33, 4 April 2016

2016-04-04T13:33:12Z

← Older revision		Revision as of 13:33, 4 April 2016
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	* Ground investigation.		* Ground investigation.
	* Ground heave.		* Ground heave.
		+	* Groundwater control in urban areas.
	* Grouting in civil engineering.		* Grouting in civil engineering.
	* Institution of Civil Engineers.		* Institution of Civil Engineers.

Designing Buildings at 10:30, 21 March 2016

2016-03-21T10:30:53Z

Designing Buildings at 07:26, 19 March 2016

2016-03-19T07:26:27Z

← Older revision		Revision as of 07:26, 19 March 2016
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	= Introduction =		= Introduction =

−	The term sinkhole ~~has appeared more and more~~ in the ~~news in recent months. Since~~ the ~~beginning~~ of the ~~year sinkholes have appeared in St Albans in the UK, Naples in Italy, New York, Mississippi and Florida in USA, throughout China and in Queensland, Australia, among many others~~.	+	The term 'sinkhole' is usually used to describe a surface depression, hollow or collapse feature occurring above a cavity in the ground formed by the solution of rock by the passage of water over time. There are six main types of sinkhole as classified by Waltham et al. (2005):

−	~~But what causes sinkholes – and what can civil engineers do about them?~~	+	* Dissolution sinkhole.
		+	* Collapse sinkhole.
		+	* Dropout sinkhole.
		+	* Buried sinkhole.
		+	* Caprock sinkhole.
		+	* Suffosion sinkhole.

−	~~= What is~~ a ~~sinkhole? =~~	+	Sinkholes can also form above cavities that occur as a result of other processes such as the emptying of liquid lava inside a lava flow (a Thurston Tube), ice wedging in cold climates, or large-scale movement of rock leaving chasms, known as ‘guls’.

−	The term sinkhole is ~~usually used~~ to ~~describe a surface depression, hollow or collapse feature occurring above a cavity in~~ the ~~ground formed by the solution~~ of ~~rock by the passage of water over time. There are six main types of sinkhole as classified by Waltham et al~~. ~~(2005):~~	+	In the UK, there has been a long history of mining and water abstraction, which in some areas has left a legacy of man-made cavities. The term sinkhole in the UK, is often extended to cover the collapse of ground into such man-made features.

−	* dissolution sinkhole	+	Suffosion and dropout sinkholes form entirely within the soil profile above the cavity with infiltrating water washing soil down into open discontinuities in the rockhead. Dissolution, collapse and caprock sinkholes are all dependent on solution and rock mechanics processes that generally occur over geological timescales related to the solubility and other properties of the country rockmass.
−	* collapse sinkhole	+
−	* dropout sinkhole	+
−	* buried sinkhole	+
−	* caprock sinkhole	+
−	* suffosion sinkhole	+
−		+
−	Sinkholes can also form above cavities that occur as a result of other processes such as the emptying of liquid lava inside a lava flow (a Thurston Tube), or ice wedging in cold climates, or large-scale movement of rock leaving chasms, known as ‘guls’.	+
−		+
−	In the UK, there has been a long history of mining and water abstraction, which in some areas has left a legacy of man-made cavities. The term sinkhole is, in the UK, often extended to cover the collapse of ground into such man-made features.	+
−		+
−	Suffosion and dropout sinkholes form entirely within the soil profile above the cavity with infiltrating water washing soil down into open discontinuities in the rockhead. Dissolution, collapse and caprock sinkholes are all dependent on solution and rock mechanics processes that generally occur over geological ~~time~~ related to the solubility and other properties of the country rockmass.	+

	= What causes a sinkhole? =		= What causes a sinkhole? =

← Older revision		Revision as of 10:30, 21 March 2016
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	The collapse of ground above cavities and the formation of sinkholes is almost always the result of concentrated flow of water. This might arise as a result of rainfall runoff, the construction of a soakaway, or as a result of fractured water or waste pipes or changes in natural drainage such as drawing down of the water table for major civil or mining works. Tony Waltham, went so far as to title his recent Geological Society Glossop Medal presentation, ‘Control the Drainage: The Gospel According to Sinkholes’.		The collapse of ground above cavities and the formation of sinkholes is almost always the result of concentrated flow of water. This might arise as a result of rainfall runoff, the construction of a soakaway, or as a result of fractured water or waste pipes or changes in natural drainage such as drawing down of the water table for major civil or mining works. Tony Waltham, went so far as to title his recent Geological Society Glossop Medal presentation, ‘Control the Drainage: The Gospel According to Sinkholes’.

−	On rare occasions, cavities have collapsed as a result of the failure of man-made caps, with disastrous consequences. In such cases, it ~~may be~~ found that the cap was simply made by placing railway sleepers over a narrow shaft entrance, ~~which~~ have rotted with time, or masonry which has been buried, forgotten and not maintained.	+	On rare occasions, cavities have collapsed as a result of the failure of man-made caps, with disastrous consequences. In such cases, it ha been found that the cap was simply made by placing railway sleepers over a narrow shaft entrance, and these have rotted with time, or masonry which has been buried, forgotten and not maintained.

	= What can civil engineers do to prevent/avoid sinkholes? =		= What can civil engineers do to prevent/avoid sinkholes? =

−	Sinkholes most commonly occur ~~worldwide~~ within naturally occurring karst landscape that is characterised by the formation of underground drainage and cavities ~~formed by~~ dissolution of soluble rocks such as limestone or gypsum. Civil engineers are best served by seeking advice from geological engineering colleagues familiar with karst geohazards. Clues to the presence of sinkholes may also be found in historical records of mining and old maps.	+	Sinkholes most commonly occur within naturally occurring karst landscape that is characterised by the formation of underground drainage and cavities from the dissolution of soluble rocks such as limestone or gypsum. Civil engineers are best served by seeking advice from geological engineering colleagues familiar with karst geohazards. Clues to the presence of sinkholes may also be found in historical records of mining and old maps.

−	The first step in high-risk areas is normally to consult the national database of natural and man-made cavities to establish whether known features exist close to a particular site. A general level of the hazard posed by natural features can be established using published methodologies, applying topographic and geological data. Sinkholes and Subsidence: Karst and Cavernous Rocks in Engineering and Construction, by Waltham, Bell and Culshaw, 2005, is an important resource.	+	The first step in high-risk areas is normally to consult the national database of natural and man-made cavities to establish whether known features exist close to a particular site. The general level of the hazard posed by natural features can be established using published methodologies, applying topographic and geological data. Sinkholes and Subsidence: Karst and Cavernous Rocks in Engineering and Construction, by Waltham, Bell and Culshaw, 2005, is an important resource.

	In areas of higher risk it is usual to ensure that utilities can tolerate distortion without rupture and to avoid building soakaways or other features that could lead to concentrated water infiltration. Changes in the ground surface, such as depressions, circular cracks or ponding water should be reported to local authorities. In very high risk areas, special ground investigation techniques can be used to refine risk assessments, and if necessary cavities can be located and filled to prevent future collapse.		In areas of higher risk it is usual to ensure that utilities can tolerate distortion without rupture and to avoid building soakaways or other features that could lead to concentrated water infiltration. Changes in the ground surface, such as depressions, circular cracks or ponding water should be reported to local authorities. In very high risk areas, special ground investigation techniques can be used to refine risk assessments, and if necessary cavities can be located and filled to prevent future collapse.

−	Boring of tunnels into unknown features or cavities poses a significant risk to both the construction teams and to property overhead. Tunnelling into water filled cavities or where water bodies can flow catastrophically into an excavation are particularly hazardous. Tunnelling works in high risk areas or where abandoned wells or mine shafts might be expected require particular attention during investigation phases, with techniques selected according to the conditions at any given site.	+	Boring tunnels into unknown features or cavities poses a significant risk to both the construction teams and to property overhead. Tunnelling into water filled cavities or where water bodies can flow catastrophically into an excavation are particularly hazardous. Tunnelling works in high-risk areas or where abandoned wells or mine shafts might be expected require particular attention during investigation phases, with techniques selected according to the conditions at any given site.

−	Probabilistic models for predicting sinkhole development have been proposed to inform the management of the risk from this geohazard to major infrastructure projects. ~~The authors recommend caution~~ in the application and reliance on these methods and ~~stress~~ the importance of experience and fully understanding the geological and civil engineering factors that have caused the formation of the sinkholes and related features.	+	Probabilistic models for predicting sinkhole development have been proposed to inform the management of the risk from this geohazard to major infrastructure projects. Caution is recommended in the application and reliance on these methods and attention given to the importance of experience and fully understanding the geological and civil engineering factors that have caused the formation of the sinkholes and related features.

	= What can civil engineers do to repair sinkholes? =		= What can civil engineers do to repair sinkholes? =

−	Generally, when ~~the~~ triggering action that has caused the development of a sinkhole (such as flow of water) is removed, the immediate risk to the surrounding area is substantially reduced. It is normal practice to fill smaller holes (those that commonly occur in the UK are typically less than 1000 m3 in volume) using weak concrete pumped into the hole from a safe distance. Depending on the circumstances, the sink hole is usually stabilised by concrete or other engineered infill.	+	Generally, when a triggering action that has caused the development of a sinkhole (such as flow of water) is removed, the immediate risk to the surrounding area is substantially reduced. It is normal practice to fill smaller holes (those that commonly occur in the UK are typically less than 1000 m3 in volume) using weak concrete pumped into the hole from a safe distance. Depending on the circumstances, the sink hole is usually stabilised by concrete or other engineered infill.

−	Minor settlements occur for several months afterwards as the weight of the concrete settles in. New sinkholes are nearly always formed by inflow of water ~~as noted above~~ and are therefore largely avoided by attention to good civil engineering practices – particularly appropriate surface drainage and avoidance of large scale changes to the water table.	+	Minor settlements occur for several months afterwards as the weight of the concrete settles in. New sinkholes are nearly always formed by inflow of water and are therefore largely avoided by attention to good civil engineering practices, particularly appropriate surface drainage and avoidance of large-scale changes to the water table.

−	It is essential to investigate the cause of the sinkhole if it is unknown, to understand the lateral and vertical extent of the related cavities ~~and~~ to check the stability remaining cavities were necessary and to monitor changes that are ongoing. The potential complexity of ground conditions that can lead to sinkhole formation must be recognised and specialist advice is required.	+	It is essential to investigate the cause of the sinkhole if it is unknown, to understand the lateral and vertical extent of the related cavities, to check the stability of remaining cavities were necessary and to monitor changes that are ongoing. The potential complexity of ground conditions that can lead to sinkhole formation must be recognised and specialist advice is required.

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