The landscape of Yorkshire can provide engineers with many different challenges on a day-to-day basis. These challenges can have an impact on all areas of civil engineering including infrastructure, flood defence and drainage, coastal erosion, utilities and transportation. Due to certain characteristics of the area, Yorkshire has geotechnical qualities that must be considered when embarking on any engineering or construction work. The geology of Yorkshire is also incredibly variable which is the reason why it has been and still is being exploited heavily for resources, including coal mining and for gypsum.
Large areas of Yorkshire are covered with a mantle of glacial clay deposited during the last ice age. This material has a potential to heave or shrink with seasonal changes in water content and with the action of vegetation such as trees. This has a serious impact upon the foundations of existing and proposed developments. Similarly, anthropogenic materials such as steel slag, a by-product of steel manufacturing, has the potential to heave and shrink significantly with differing levels of moisture. This also presents challenges to today’s engineers.
Mine subsidence has proven over the years to be a major challenge to geotechnical engineers in the Yorkshire region, and has been known to be detrimental to a buildings lifespan. If investigated beforehand, early identification can save time and money.
In general terms, mine subsidence is caused by underground mine workings collapsing or failing, usually taking the form of troughs and crown holes.
Troughs can occur above abandoned mines that can be found throughout the Yorkshire region; due to the mining heritage of the area. Various triggers can cause the ground to trough. Troughs are usually caused when overburden sags downwards due to the collapsing of mine pillars; caused by the puncturing of the pillars into the roof of the mine. This can occur many decades after the mine were decommissioned, making it very hard to predict such triggers. Mining and related industries have also left a legacy of mining induced geological faulting along with ground/groundwater contamination and fugitive ground gases.
Crown holes can occur within different types of mines. They are usually found on shallow room-and-pillar mines that are less than 30 metres in depth, resulting in the change in ground surface. Crown holes usually occur on a certain part of the mine, sometimes on a big scale. Crown holes have been known to be responsible for extensive damage to property throughout the UK.
The potential impact of mining subsidence to structures in Yorkshire can be huge. On a cosmetic level, the physical appearance of the structure can be affected, including cracks in plaster and render or cracks in dry walls.
In terms of structural issues, these range from damage occurring to doors and windows, jamming them, to more serious issues that could lead to entire foundations having to be replaced resulting from cracked footings and walls.
In and around Yorkshire, not only do geotechnical engineers need to be aware of mining subsidence, they have to consider various other geotechnical factors. One that is becoming more of an issue than ever is coastal erosion.
Coastal erosion is a natural problem that occurs when the edge of the coast is worn away by the elements, accelerated by extreme weather conditions.
On a more extreme level, attrition can be one of the leading factors in coastal erosion. Coastal wind and tidal action is the major cause of attrition (sometimes referred to as weathering), where rock is worn down against other rock causing them to form smooth pebbles. Sometimes known as corrosion, abrasion is also a leading factor to consider when looking into coastal erosion. Waves that are out of the ordinary in size, wearing down sea cliffs, can cause abrasion. Rocks are carried along by fast-moving waves, they are smashed against the cliff edge and this, overtime, can cause major damage culminating with the upper cliff becoming unstable or detached.
Air pressure can also be a contributing factor to coastal erosion. Hydraulic Action erosion, occurs where air is forced into tiny cracks and crevasses by breaking waves, causing the wall to weaken and collapse.
Last but not least is actual corrosion of the rock. Corrosion is where a material, in this case rock with high pH, is exposed with water with low pH that causes a chemical reaction leading to the breakdown of the rocks structure.
Combining all of the above types of coastal erosion with the chemical breakdown of the rock, can cause an area of coastline to quite rapidly suffer from geotechnical issues.
Geotechnical engineers in Yorkshire can monitor and predict coastal erosion on a large scale however risk has to be managed so coastal barriers and methods are more efficient.
Coastal erosion can be predicted using aerial photographs, maps and surveys of specific areas. The history of areas prone to erosion can be researched, helping geotechnical engineers understand how and when coastal erosion could happen in the future. This information can be used to measure rate, impact, and effectiveness of previous methods and help to generate discussions on future management of coastal erosion.
Geotechnical engineers are also heavily involved in the construction of transport infrastructure. Within Yorkshire, one key area of infrastructure is roads and motorways. In particular, one motorway has provided many challenges to geotechnical engineers. This motorway is the M62.
The motorway connects the Lancashire County boundary to Pole Moor and is a very unique part of the UK's transport infrastructure. The motorway has various areas of interest including the largest rock fill dam in the UK and several key bridges. Along with the dam, various other details of the motorway have caused geotechnical engineers unique challenges.
The motorway crosses an ancient path; 'The Pennine Way' and the engineers at the time had to incorporate a 65ft concrete arch for walkers to cross. At the point where The Pennine Way crosses the motorway, the highways at its highest point in the Pennine hills and is six lanes wide.
As the motorway cuts through a main section of the Pennines, this required several severe rock cuttings on a large scale and was a major challenge to the geotechnical engineers. One typical section had 12 million cubic yards of material and 8 million cubic yards of solid rock moved to make way for the M62 motorway.
The material also had specific qualities that made the job even more difficult. For example, one of the first jobs to be carried out was to remove 650,000 cubic yards of peat which had no bearing weight capacity and couldn't even support the weight of a man, not to mention construction vehicles.
After the contractors lost a couple of excavators to the peat bog, they had to engineer a different method of excavation. This was done by cutting straight through the peat and running the plant and equipment on the underlying material, the peat was then removed from the exposed vertical face. The peat had no value and was stacked on the hillsides adjacent to the M62 to be landscaped into the surrounding areas and is still present today.
Along with the geotechnical challenges faced by the construction of the M62, the engineering and construction teams were faced with some very harsh weather conditions, however this tough geotechnical engineering challenge was completed within 5 years.
Large areas of Yorkshire are covered with a mantle of glacial clay deposited during the last ice age. This material has a potential to heave or shrink with seasonal changes in water content and with the action of vegetation such as trees. This has a serious impact upon the foundations of existing and proposed developments. Similarly, anthropogenic materials such as steel slag, a by-product of steel manufacturing, has the potential to heave and shrink significantly with differing levels of moisture. This also presents challenges to today’s engineers.
Mine subsidence has proven over the years to be a major challenge to geotechnical engineers in the Yorkshire region, and has been known to be detrimental to a buildings lifespan. If investigated beforehand, early identification can save time and money.
In general terms, mine subsidence is caused by underground mine workings collapsing or failing, usually taking the form of troughs and crown holes.
Troughs can occur above abandoned mines that can be found throughout the Yorkshire region; due to the mining heritage of the area. Various triggers can cause the ground to trough. Troughs are usually caused when overburden sags downwards due to the collapsing of mine pillars; caused by the puncturing of the pillars into the roof of the mine. This can occur many decades after the mine were decommissioned, making it very hard to predict such triggers. Mining and related industries have also left a legacy of mining induced geological faulting along with ground/groundwater contamination and fugitive ground gases.
Crown holes can occur within different types of mines. They are usually found on shallow room-and-pillar mines that are less than 30 metres in depth, resulting in the change in ground surface. Crown holes usually occur on a certain part of the mine, sometimes on a big scale. Crown holes have been known to be responsible for extensive damage to property throughout the UK.
The potential impact of mining subsidence to structures in Yorkshire can be huge. On a cosmetic level, the physical appearance of the structure can be affected, including cracks in plaster and render or cracks in dry walls.
In terms of structural issues, these range from damage occurring to doors and windows, jamming them, to more serious issues that could lead to entire foundations having to be replaced resulting from cracked footings and walls.
In and around Yorkshire, not only do geotechnical engineers need to be aware of mining subsidence, they have to consider various other geotechnical factors. One that is becoming more of an issue than ever is coastal erosion.
Coastal erosion is a natural problem that occurs when the edge of the coast is worn away by the elements, accelerated by extreme weather conditions.
On a more extreme level, attrition can be one of the leading factors in coastal erosion. Coastal wind and tidal action is the major cause of attrition (sometimes referred to as weathering), where rock is worn down against other rock causing them to form smooth pebbles. Sometimes known as corrosion, abrasion is also a leading factor to consider when looking into coastal erosion. Waves that are out of the ordinary in size, wearing down sea cliffs, can cause abrasion. Rocks are carried along by fast-moving waves, they are smashed against the cliff edge and this, overtime, can cause major damage culminating with the upper cliff becoming unstable or detached.
Air pressure can also be a contributing factor to coastal erosion. Hydraulic Action erosion, occurs where air is forced into tiny cracks and crevasses by breaking waves, causing the wall to weaken and collapse.
Last but not least is actual corrosion of the rock. Corrosion is where a material, in this case rock with high pH, is exposed with water with low pH that causes a chemical reaction leading to the breakdown of the rocks structure.
Combining all of the above types of coastal erosion with the chemical breakdown of the rock, can cause an area of coastline to quite rapidly suffer from geotechnical issues.
Geotechnical engineers in Yorkshire can monitor and predict coastal erosion on a large scale however risk has to be managed so coastal barriers and methods are more efficient.
Coastal erosion can be predicted using aerial photographs, maps and surveys of specific areas. The history of areas prone to erosion can be researched, helping geotechnical engineers understand how and when coastal erosion could happen in the future. This information can be used to measure rate, impact, and effectiveness of previous methods and help to generate discussions on future management of coastal erosion.
Geotechnical engineers are also heavily involved in the construction of transport infrastructure. Within Yorkshire, one key area of infrastructure is roads and motorways. In particular, one motorway has provided many challenges to geotechnical engineers. This motorway is the M62.
The motorway connects the Lancashire County boundary to Pole Moor and is a very unique part of the UK's transport infrastructure. The motorway has various areas of interest including the largest rock fill dam in the UK and several key bridges. Along with the dam, various other details of the motorway have caused geotechnical engineers unique challenges.
The motorway crosses an ancient path; 'The Pennine Way' and the engineers at the time had to incorporate a 65ft concrete arch for walkers to cross. At the point where The Pennine Way crosses the motorway, the highways at its highest point in the Pennine hills and is six lanes wide.
As the motorway cuts through a main section of the Pennines, this required several severe rock cuttings on a large scale and was a major challenge to the geotechnical engineers. One typical section had 12 million cubic yards of material and 8 million cubic yards of solid rock moved to make way for the M62 motorway.
The material also had specific qualities that made the job even more difficult. For example, one of the first jobs to be carried out was to remove 650,000 cubic yards of peat which had no bearing weight capacity and couldn't even support the weight of a man, not to mention construction vehicles.
After the contractors lost a couple of excavators to the peat bog, they had to engineer a different method of excavation. This was done by cutting straight through the peat and running the plant and equipment on the underlying material, the peat was then removed from the exposed vertical face. The peat had no value and was stacked on the hillsides adjacent to the M62 to be landscaped into the surrounding areas and is still present today.
Along with the geotechnical challenges faced by the construction of the M62, the engineering and construction teams were faced with some very harsh weather conditions, however this tough geotechnical engineering challenge was completed within 5 years.