31-03-2010, 12:46 PM
all details of seminar
31-03-2010, 12:46 PM
all details of seminar
04-04-2011, 02:10 PM
SYPGNSP.ppt (Size: 846.5 KB / Downloads: 553) What is ground improvement technique? Ground improvement technique is the process of improving the geo-technical characteristics of soil used in construction TYPES OF GROUND IMPROVEMENT TECHNIQUES COMPACTION PILE BLASTING PRE-COMPRESSION STONE COLUMN VIBROFLOATATION GROUTING ELECTRO OSMOSIS THERMAL TREATMENT GROUTING Grouting is a process where by fluid like material, either in suspension or in solution form are injected into subsurface soil or rock to achieve a decrease in permeability and compressibility AIMS OF GROUTING To decrease the permeability. To increase the shear strength. To decrease the compressibility GROUT PROVES MORE EFFECTIVE IN THE FOLLOWING CASES When the foundation has to be constructed below ground water table. When there is difficult to the foundation level (ex: city work, tunnel shafts,sewers, subway construction). When the geometric dimensions of the foundations are complicated and involved many boundaries and contact zones. When the adjacent structure require that the soil of the foundation strata should not be excavated CLASSIFICATION OF GROUT MATERIALS SUSPENSION GROUT EMULSION GROUT SOLUTION GROUT EMULSION GROUT These consists of emulsion of colloidal droplets of liquid in a dispersed phase. Ex: Bitumen, foams created by emulsifying a gas into cement etc. TYPES OF GROUTING JET GROUTING The ASCE Geotechnical Engineering Division Committee on grouting defined Jet grouting as a “technique utilizing a special drill bit with horizontal and vertical high speed water jets to excavate alluvial soils and produce hard impervious column by pumping grout through the horizontal nozzles that jets and mixes with foundation material as the drill bit is with drawn”. Advantages Nearly all soil types grout able Designable strength & permeability No harmful vibrations Can be performed in limited workspace Maintenance free Safest method of under pinning construction Much faster than alternative method GROUTING CONTROL Monitoring the grout taken as a function of pressure Observing ground heave Digging inspection pits Retrieving Core samples for examination and laboratory testing Conducting borehole permeability tests.
17-03-2014, 10:15 AM
Ground Improvement Technology Abstract The ground can be improved by adapting certain ground improvement technology. Vibro-compaction increases the density of the soil by using powerful depth vibrators. Vacuum consolidation is used for improving soft soils by using a vacuum pump. Preloading method is used to remove pore water over time. Heating is used to form a crystalline or glass product by electric current. Ground freezing converts pore water to ice to increase their combined strength and make them impervious. Rapid urban and industrial growth demands more land for further development. In order to meet this demand land reclamation and utilization of unsuitable and environmentally affected lands have been taken up. These, hitherto useless lands for construction have been converted to be useful ones by adopting one or more ground improvement technology. Vibro-Compaction Vibro-compaction, sometimes referred to as Vibro floation, is the rearrangement of soil particles into a denser configuration by the use of powerful depth vibration . Vibro compaction is a ground improvement process for densifying loose sands to create stable foundation soils. The principle behind vibro compaction is simple. The combined action of vibration and water saturation by jetting rearranges loose sand grains into a more compact state. Vibro compaction is performed with specially-designed vibrating probes. Both horizontal and vertical modes of vibration have been used in the past. The vibrators used by Terra Systems consist of torpedo-shaped probes 12 to 16 inches in diameter which vibrates at frequencies typically in the range of 30 to 50 Hz. APPLICATIONS: Reduction of foundation settlements. Reduction of risk of liquefaction due to seismic activity. Permit construction on granular fills. HEATING Heating or vitrifaction breaks the soil particle down to form a crystalline or glass product. It uses electrical current to heat the soil and modify the physical characteristics of the soil. Heating soils permanently alters the properties of the soil. Depending on the soil, temperatures can range between 300 and 1000 degree Celsius. APPLICATIONS: Immobilization of radioactive or contaminated soil Densification and stabilization VIBRO-REPLACEMENT STONE COLUMNS Vibro-Replacement extends the range of soils that can be improved by vibratory techniques to include cohesive soils. Reinforcement of the soil with compacted granular columns or “stone columns” is accomplished by the top-feed method. The important Vibro-replacement stone columns are Ground conditions, Relative density, Degree of saturation, Permeation. |
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