Ground Improvement or Ground treatment is defined as “controlled alteration of the state, nature or mass behavior of ground materials to achieve an intended satisfactory response to existing or projected environmental and engineering actions”
Ground Improvement by Vibration
Vibration can be used to compact soils and fills. Similar to Vibrating rollers used to compact relatively thin layers of earth fill and bituminous road materials. It involves using vibration to densify the ground in place and to depth either by penetrating the ground with a vibrator or inducing very high level of energy at the ground surface or at defined points within the ground. Major ground treatment methods include;
- Vibro-compaction
- Vibro stone columns
- Dynamic compaction
- Rapid impact compaction
- Vibratory probing
- Compaction piles
- Blasting
Ground Improvement by Adding Load or Increasing Effective Stress
Applying load on the ground causes it to compress. The extent and time required depends on the arrangement of the ground particles, on the degree of saturation, and on how freely the soil can drain. For loose and particularly unsaturated fills, adding load induces rapid settlement.
Soft, saturated clays take months or years to consolidate under an added load while pore pressures dissipate and the effective stress in the soil increases. Major ground treatment methods include;
- Pre-compression
- Vertical drains
- Inundation
- Vacuum pre-loading
- Dewatering fine-grained soils
- Pressure berms
Ground Improvement by Structural Reinforcement
Many ground improvement methods could be considered as form of reinforcement. Stone columns are introduced materials that stiffen the ground. Major ground treatment methods include;
- Reinforced soil
- Soil nailing
- Root or micro-piles
- Slope dowels
- Embankment piles
Ground Improvement by Structural Fill
Basis of this philosophy is to replace a weak soil with a better one. Use lightweight materials instead of heavier earth fills above weak ground is a recent advancement of this method. Major ground treatment methods include;
- Removal and replacement
- Displacement
- Reducing load
Ground Improvement by Admixtures
The use of additives and admixtures, such as lime, cement, oils and bitumen and chemicals like sulphur, is one of the oldest and most widespread methods of improving a soil. Purpose of this method is to strengthen a locally available soil fill to construct a low-cost road base.
Cement stabilized soil or soil-cement, or to mix lime into highly plastic clays is a typical example. Major ground treatment methods include;
- Lime columns (Swedish method)
- Lime and cement columns (Japanese method)
- Mix-in-place by single auger or Deep Soil Mixing
- Lime stabilization of slopes
- Lime stabilization of pavements
- Cement stabilization of pavement
Ground Improvement by Grouting
Grouting can be defined as controlled injection of material, usually in a fluid phase, into soil or rock in order to improve the physical characteristics of the ground. Major ground treatment methods include;
- Grouting processes
- Permeation grouting
- Hydrofracture grouting
- Jet grouting
- Compaction, squeeze and compensation grouting
- Cavity filling
Ground Improvement by Thermal Stabilization
The removal of heat from the soil turning its pore water into ice is a very powerful technique rendering the ground impermeable and, for unconsolidated materials, making them stronger.
Applying heat to clays to drive out free pore water and, at higher temperatures, the water adsorbed on particle surfaces, creates a very hard, durable material, as when making brick or mud building blocks. Major ground treatment methods include;
- Artificial ground freezing
- Artificial ground heating
Ground Improvement by Vegetation
Combining engineering and horticulture, vegetation as ground improvement is the biological reinforcement of soil by plant roots to retain earth masses and prevent soil loss.
Source: civildigital
