Ground Improvement

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;

Ground Improvement by Dynamic Soil Compaction - — Ground Improvement by Dynamic Soil Compaction

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.