logging in or signing up ground freezing..ll rizwankhurram Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 577 Category: Education License: All Rights Reserved Like it (0) Dislike it (1) Added: September 07, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: alrakeza (17 month(s) ago) alsalam alekom that lecture i hope to add movie about instilling system of freezing Saving..... Post Reply Close By: rizwankhurram (17 month(s) ago) thnks for inform Saving..... Edit Comment Close By: sabaafzal442 (20 month(s) ago) i want to download it. Saving..... Post Reply Close Saving..... Edit Comment Close By: sabaafzal442 (20 month(s) ago) hmmmmm good presentation. Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Ground Freezing : Ground Freezing Presented By : Muhammad Husnain 2007-MS-GEO-16 Contents : Contents Introduction Factors on which Soil freezing depends How Ground Freezing Works Refrigeration systems The advantages of ground freezing Improved Soil Properties Ground freezing for shoring andgroundwater cutoff Application Introduction : Introduction Ground Freezing is adaptable to any shape, size or depth required. It is the most effective and consistently reliable method of providing temporary support and preventing groundwater from flowing into excavations. Frozen ground is nearly twice as strong as concrete and is essentially impermeable. Slide 5: The basic principle of ground freezing, which was first used in South Wales 1862, is to circulate a cold medium through a suitable pipe system, which cools the strata and thus converts the in-situ pore water to ice. The ice is so formed bonds adjacent soil particles together and forms an impermeable structure with increased strength characteristics. Its relatively high strength can be attributed in part to the binding together of soil particles with ice. Introduction Contd…. Slide 6: When wet soil freezes, the main process is the physical change of soil water from liquid to solid that turns the soil into a hard mass resembling concrete. In a porous body like soil, water exists in a network of inter-connecting pores; when it freezes, this network becomes rigid and encloses the soil particles in a solid block. If the soil is dry it cannot freeze. The largest excavation in the UK, supported totally by frozen ground, being 40 meters in diameter and 40 meters deep through unconsolidated alluvial deposits. Introduction Contd…. Factors on which Soil freezing depends : Factors on which Soil freezing depends Factors on which soil freezing depends are : Its thermal properties, Moisture content Air temperature. The most important is the amount of water to be frozen. The conductivity of the soil particles and water content all influence the over-all thermal conductivity of soil. Because clay particles have a higher insulation value than silt or sand particles and since clay soils normally hold more moisture than silts and sands. Other Factors : Other Factors There are other factors that influence the depth of freezing. The insulating effect of snow deserves special mention. It has been shown that each foot of undisturbed snow reduces the depth of soil freezing by approximately the same amount. Among meteorological factors such as Air temperature (probably the most significant) Sunshine Precipitation Wind velocity How Ground Freezing Works : How Ground Freezing Works There are many ways to freeze the ground, including liquid nitrogen, brine, carbon dioxide. We use chilled calcium chloride brine circulating through a series of closed-ended steel pipes in the ground. How Ground Freezing Works Contd…. : The -10°F to -20°F brine circulates down along the outside pipe and up through an inside pipe thus freezing the soil around the pipes. It is a completely closed and tested system so that no brine goes into the ground. The methods of ground freezing are reliable and environmentally safe (calcium chloride is non-toxic and sprayed on icy roads in many states). Frozen soil can be nearly as strong as concrete and is impermeable, making it ideal for shoring and groundwater cutoff. How Ground Freezing Works Contd…. Refrigeration systems : Refrigeration systems There are two methods of providing refrigeration energy to freeze the ground. Conventional system Cryogenic systems Conventional system : Conventional system The conventional system consists of a primary refrigerate gas, usually ammonia, being compressed and conducting its cold energy on evaporation to a secondary coolant, usually calcium chloride brine which is circulated through the freeze tube system to cool the strata. The refrigeration plants used for this operation are mounted on skid units for easy transportation. In operation the ammonia does not leave the confines of the skid unit and is protected by a series of safety systems to protect against failure. This type self contained of system can operate at temperatures as low as -40 degrees Celsius and are suitable for the larger projects where freezing will be carried on for several weeks. Cryogenic systems : Cryogenic systems Where the construction period is of short duration the cryogenic system is generally used. This system uses an expendable refrigerant usually liquid nitrogen that is applied directly to the freeze tubes where it evaporates at -196 c and the resultant gas is exhausted to atmosphere. Cryogenic systems Contd……. : The liquid nitrogen is delivered to site by road tankers and stored in vacuum insulated vessels of up to 100 tones capacity. The system has been successfully used for example at a tunnel face beneath a river and over 1000 meters from an access shaft. Cryogenic systems Contd……. The advantages of ground freezing : : The advantages of ground freezing : Ground freezing can provide an absolute water cutoff and can be installed in difficult ground conditions. Ground freezing can be applied in the full range of soils from clay to cobbles and boulders, in pervious or fissured rock, and filled ground. Ground freezing is most effective as an earth support system where groundwater is a concern and where either pumping or cutting off the water flow cannot be readily achieved with other methods. Advantages Contd…. : Since no chemical additives are used in the freeze WALL process, it has no long-term effect on the subsurface environment. Once the refrigeration unit is turned off and the pipes abandoned, the impacted area gradually melts - usually restoring the groundwater and soil to their original states. Advantages Contd…. Improved Soil Properties : Improved Soil Properties By ground freezing the improved soil properties are: STRENGTH : Soil strength is increased many times and frequently excavations are rendered stable without any further temporary support. Frozen soil can be likened to a weak concrete or rock therefore complete stability can be assured. IMPERMEABILITY : Impermeability is common to all frozen soil types thus the requirement for dewatering or pumping is eliminated. Improved Soil Properties Contd…. : STABILITY : Settlement associated with vibration during piling and removal of fines due to pumping are eliminated. NON-POLLUTING : Freezing does not pollute the ground water or affect its level in any way. VERSATILITY: Freezing satisfactorily stabilizes and excludes ground water in all types of ground from fine micro-grain to fissured rock structures. Improved Soil Properties Contd…. Ground Freezing For Shoring AndGroundwater Cutoff : Ground Freezing For Shoring AndGroundwater Cutoff Shallow Excavations—Small Site Shallow Excavations—Large Site Deep Excavations Tunneling Groundwater Cutoff Wall SHALLOW EXCAVATIONSNatural Groundwater Cutoff at Shallow Depth : SHALLOW EXCAVATIONSNatural Groundwater Cutoff at Shallow Depth Cuts off groundwater along sides and bottom to eliminate dewatering. Provides stable shoring with no internal bracing or struts. Batter freeze pipe can be used to allow heavy construction traffic along the top of the wall. Slide 21: Bottom concrete seal can usually be eliminated. Appropriate for excavations up to about 40 feet deep. Cost-competitive compared to conventional shoring (sheet piles, soldier pile walls). SHALLOW EXCAVATIONS Contd…. SHALLOW EXCAVATIONSLarge Site : SHALLOW EXCAVATIONSLarge Site Allows large, shallow excavations to be accomplished in the "dry" with no dewatering. Freeze pipes are installed nearly horizontal using directional drilling methods. Completely seals the site from groundwater. Slide 23: Uplift is controlled by freezing deeper than the planned excavation. Adapts to sites of variable size and shape with lengths up to 1,000 feet. Can also be used to cut off groundwater beneath existing structures. Cost effective to depths of 60 feet or more. SHALLOW EXCAVATIONS Contd…. SHALLOW EXCAVATIONSSmall Site : SHALLOW EXCAVATIONSSmall Site Can be designed to completely cut off groundwater into the excavation without a natural aquitard. Batter freeze pipe can be installed at any angle to accommodate site space constraints. Can be modified: vertical pipes on one side and batter pipes on the other side. Slide 25: Uplift is controlled by freezing deeper than the excavation depth. Very cost-effective shoring method when contaminated groundwater is present. Can be effectively used to depths of 40 feet or more SHALLOW EXCAVATIONS Contd…. DEEP EXCAVATIONS : DEEP EXCAVATIONS DEEP EXCAVATIONSNatural Groundwater Cutoff Near Bottom of Excavation : DEEP EXCAVATIONSNatural Groundwater Cutoff Near Bottom of Excavation Circular-shape frozen soil wall provides very strong shoring without internal bracing. Has been used on hundreds of shafts worldwide to depths of 800 feet. Completely cuts off ground water to eliminate dewatering. Generally costs less than other deep shaft methods (secant concrete piles, jet grouting, etc.). Slide 28: A frozen soil seal can be created at sites where no natural groundwater cutoff is present. May be used in nearly all soil and groundwater conditions. Designed to resist uplift without expensive tie-downs. DEEP EXCAVATIONS Contd…. GROUNDWATER CUTOFF WALL : GROUNDWATER CUTOFF WALL Because frozen soil has very low permeability (less than10cm/sec) it is very effective as a groundwater cutoff. A frozen soil cutoff can be used to prevent groundwater from entering open pit mines, gravel pits, landfills and other similar facilities that are below groundwater. GROUNDWATER CUTOFF WALL Contd…. : GROUNDWATER CUTOFF WALL Contd…. Eliminates or greatly reduces the need for dewatering. Can also be used to stop the migration of contaminated groundwater near streams or lakes. Maintenance of a buried frozen soil cutoff is relatively inexpensive making it competitive for long-term cutoffs. TUNNELING : TUNNELING Provides stable shoring to allow tunneling in wet, loose soils or fractured bedrock. Effective for cutting off ground water into tunnel excavation. Frozen soil/rock can be used as shoring around unfrozen soil or the entire soil/rock mass can be frozen. Applications Bryn Mawr utility improvement project : Applications Bryn Mawr utility improvement project One of the completed projects was a frozen soil shoring wall around a 20-foot-deep excavation along Interstate 405 for retaining a vertical cut during construction of a large storm water detention vault. Applications2-Condominium in Madison Park. : Applications2-Condominium in Madison Park. The second was a frozen soil shoring wall around a 10-foot deep basement excavation for a condominium located in Madison Park just 8 feet from Lake Washington. References : References Geografiska Annaler, By Charles Harris, (Some Factors Affecting the Rates and Processes of Periglacial Mass Movements) http://www.bdf.co.uk/freeze.htm http://www.cryocell.com/CivilApp.html http://www.djc.com/special/design98 Slide 35: THANKS You do not have the permission to view this presentation. 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ground freezing..ll rizwankhurram Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 577 Category: Education License: All Rights Reserved Like it (0) Dislike it (1) Added: September 07, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: alrakeza (17 month(s) ago) alsalam alekom that lecture i hope to add movie about instilling system of freezing Saving..... Post Reply Close By: rizwankhurram (17 month(s) ago) thnks for inform Saving..... Edit Comment Close By: sabaafzal442 (20 month(s) ago) i want to download it. Saving..... Post Reply Close Saving..... Edit Comment Close By: sabaafzal442 (20 month(s) ago) hmmmmm good presentation. Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Ground Freezing : Ground Freezing Presented By : Muhammad Husnain 2007-MS-GEO-16 Contents : Contents Introduction Factors on which Soil freezing depends How Ground Freezing Works Refrigeration systems The advantages of ground freezing Improved Soil Properties Ground freezing for shoring andgroundwater cutoff Application Introduction : Introduction Ground Freezing is adaptable to any shape, size or depth required. It is the most effective and consistently reliable method of providing temporary support and preventing groundwater from flowing into excavations. Frozen ground is nearly twice as strong as concrete and is essentially impermeable. Slide 5: The basic principle of ground freezing, which was first used in South Wales 1862, is to circulate a cold medium through a suitable pipe system, which cools the strata and thus converts the in-situ pore water to ice. The ice is so formed bonds adjacent soil particles together and forms an impermeable structure with increased strength characteristics. Its relatively high strength can be attributed in part to the binding together of soil particles with ice. Introduction Contd…. Slide 6: When wet soil freezes, the main process is the physical change of soil water from liquid to solid that turns the soil into a hard mass resembling concrete. In a porous body like soil, water exists in a network of inter-connecting pores; when it freezes, this network becomes rigid and encloses the soil particles in a solid block. If the soil is dry it cannot freeze. The largest excavation in the UK, supported totally by frozen ground, being 40 meters in diameter and 40 meters deep through unconsolidated alluvial deposits. Introduction Contd…. Factors on which Soil freezing depends : Factors on which Soil freezing depends Factors on which soil freezing depends are : Its thermal properties, Moisture content Air temperature. The most important is the amount of water to be frozen. The conductivity of the soil particles and water content all influence the over-all thermal conductivity of soil. Because clay particles have a higher insulation value than silt or sand particles and since clay soils normally hold more moisture than silts and sands. Other Factors : Other Factors There are other factors that influence the depth of freezing. The insulating effect of snow deserves special mention. It has been shown that each foot of undisturbed snow reduces the depth of soil freezing by approximately the same amount. Among meteorological factors such as Air temperature (probably the most significant) Sunshine Precipitation Wind velocity How Ground Freezing Works : How Ground Freezing Works There are many ways to freeze the ground, including liquid nitrogen, brine, carbon dioxide. We use chilled calcium chloride brine circulating through a series of closed-ended steel pipes in the ground. How Ground Freezing Works Contd…. : The -10°F to -20°F brine circulates down along the outside pipe and up through an inside pipe thus freezing the soil around the pipes. It is a completely closed and tested system so that no brine goes into the ground. The methods of ground freezing are reliable and environmentally safe (calcium chloride is non-toxic and sprayed on icy roads in many states). Frozen soil can be nearly as strong as concrete and is impermeable, making it ideal for shoring and groundwater cutoff. How Ground Freezing Works Contd…. Refrigeration systems : Refrigeration systems There are two methods of providing refrigeration energy to freeze the ground. Conventional system Cryogenic systems Conventional system : Conventional system The conventional system consists of a primary refrigerate gas, usually ammonia, being compressed and conducting its cold energy on evaporation to a secondary coolant, usually calcium chloride brine which is circulated through the freeze tube system to cool the strata. The refrigeration plants used for this operation are mounted on skid units for easy transportation. In operation the ammonia does not leave the confines of the skid unit and is protected by a series of safety systems to protect against failure. This type self contained of system can operate at temperatures as low as -40 degrees Celsius and are suitable for the larger projects where freezing will be carried on for several weeks. Cryogenic systems : Cryogenic systems Where the construction period is of short duration the cryogenic system is generally used. This system uses an expendable refrigerant usually liquid nitrogen that is applied directly to the freeze tubes where it evaporates at -196 c and the resultant gas is exhausted to atmosphere. Cryogenic systems Contd……. : The liquid nitrogen is delivered to site by road tankers and stored in vacuum insulated vessels of up to 100 tones capacity. The system has been successfully used for example at a tunnel face beneath a river and over 1000 meters from an access shaft. Cryogenic systems Contd……. The advantages of ground freezing : : The advantages of ground freezing : Ground freezing can provide an absolute water cutoff and can be installed in difficult ground conditions. Ground freezing can be applied in the full range of soils from clay to cobbles and boulders, in pervious or fissured rock, and filled ground. Ground freezing is most effective as an earth support system where groundwater is a concern and where either pumping or cutting off the water flow cannot be readily achieved with other methods. Advantages Contd…. : Since no chemical additives are used in the freeze WALL process, it has no long-term effect on the subsurface environment. Once the refrigeration unit is turned off and the pipes abandoned, the impacted area gradually melts - usually restoring the groundwater and soil to their original states. Advantages Contd…. Improved Soil Properties : Improved Soil Properties By ground freezing the improved soil properties are: STRENGTH : Soil strength is increased many times and frequently excavations are rendered stable without any further temporary support. Frozen soil can be likened to a weak concrete or rock therefore complete stability can be assured. IMPERMEABILITY : Impermeability is common to all frozen soil types thus the requirement for dewatering or pumping is eliminated. Improved Soil Properties Contd…. : STABILITY : Settlement associated with vibration during piling and removal of fines due to pumping are eliminated. NON-POLLUTING : Freezing does not pollute the ground water or affect its level in any way. VERSATILITY: Freezing satisfactorily stabilizes and excludes ground water in all types of ground from fine micro-grain to fissured rock structures. Improved Soil Properties Contd…. Ground Freezing For Shoring AndGroundwater Cutoff : Ground Freezing For Shoring AndGroundwater Cutoff Shallow Excavations—Small Site Shallow Excavations—Large Site Deep Excavations Tunneling Groundwater Cutoff Wall SHALLOW EXCAVATIONSNatural Groundwater Cutoff at Shallow Depth : SHALLOW EXCAVATIONSNatural Groundwater Cutoff at Shallow Depth Cuts off groundwater along sides and bottom to eliminate dewatering. Provides stable shoring with no internal bracing or struts. Batter freeze pipe can be used to allow heavy construction traffic along the top of the wall. Slide 21: Bottom concrete seal can usually be eliminated. Appropriate for excavations up to about 40 feet deep. Cost-competitive compared to conventional shoring (sheet piles, soldier pile walls). SHALLOW EXCAVATIONS Contd…. SHALLOW EXCAVATIONSLarge Site : SHALLOW EXCAVATIONSLarge Site Allows large, shallow excavations to be accomplished in the "dry" with no dewatering. Freeze pipes are installed nearly horizontal using directional drilling methods. Completely seals the site from groundwater. Slide 23: Uplift is controlled by freezing deeper than the planned excavation. Adapts to sites of variable size and shape with lengths up to 1,000 feet. Can also be used to cut off groundwater beneath existing structures. Cost effective to depths of 60 feet or more. SHALLOW EXCAVATIONS Contd…. SHALLOW EXCAVATIONSSmall Site : SHALLOW EXCAVATIONSSmall Site Can be designed to completely cut off groundwater into the excavation without a natural aquitard. Batter freeze pipe can be installed at any angle to accommodate site space constraints. Can be modified: vertical pipes on one side and batter pipes on the other side. Slide 25: Uplift is controlled by freezing deeper than the excavation depth. Very cost-effective shoring method when contaminated groundwater is present. Can be effectively used to depths of 40 feet or more SHALLOW EXCAVATIONS Contd…. DEEP EXCAVATIONS : DEEP EXCAVATIONS DEEP EXCAVATIONSNatural Groundwater Cutoff Near Bottom of Excavation : DEEP EXCAVATIONSNatural Groundwater Cutoff Near Bottom of Excavation Circular-shape frozen soil wall provides very strong shoring without internal bracing. Has been used on hundreds of shafts worldwide to depths of 800 feet. Completely cuts off ground water to eliminate dewatering. Generally costs less than other deep shaft methods (secant concrete piles, jet grouting, etc.). Slide 28: A frozen soil seal can be created at sites where no natural groundwater cutoff is present. May be used in nearly all soil and groundwater conditions. Designed to resist uplift without expensive tie-downs. DEEP EXCAVATIONS Contd…. GROUNDWATER CUTOFF WALL : GROUNDWATER CUTOFF WALL Because frozen soil has very low permeability (less than10cm/sec) it is very effective as a groundwater cutoff. A frozen soil cutoff can be used to prevent groundwater from entering open pit mines, gravel pits, landfills and other similar facilities that are below groundwater. GROUNDWATER CUTOFF WALL Contd…. : GROUNDWATER CUTOFF WALL Contd…. Eliminates or greatly reduces the need for dewatering. Can also be used to stop the migration of contaminated groundwater near streams or lakes. Maintenance of a buried frozen soil cutoff is relatively inexpensive making it competitive for long-term cutoffs. TUNNELING : TUNNELING Provides stable shoring to allow tunneling in wet, loose soils or fractured bedrock. Effective for cutting off ground water into tunnel excavation. Frozen soil/rock can be used as shoring around unfrozen soil or the entire soil/rock mass can be frozen. Applications Bryn Mawr utility improvement project : Applications Bryn Mawr utility improvement project One of the completed projects was a frozen soil shoring wall around a 20-foot-deep excavation along Interstate 405 for retaining a vertical cut during construction of a large storm water detention vault. Applications2-Condominium in Madison Park. : Applications2-Condominium in Madison Park. The second was a frozen soil shoring wall around a 10-foot deep basement excavation for a condominium located in Madison Park just 8 feet from Lake Washington. References : References Geografiska Annaler, By Charles Harris, (Some Factors Affecting the Rates and Processes of Periglacial Mass Movements) http://www.bdf.co.uk/freeze.htm http://www.cryocell.com/CivilApp.html http://www.djc.com/special/design98 Slide 35: THANKS