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.
Full Answer
How can the ground be improved?
How is load transferred from the backfill soil to the strip reinforcement?
How does vibro compaction work?
What is preloading soil?
What is jet grouting?
What is ground freezing?
What is vacuum consolidation?
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About this website
What is the ground improvement techniques?
Ground Improvement techniques may include Soil Stabilisation, Vibro Stone Columns, Jet Grouting, Deep Soil Mixing, Dynamic Compaction. Why should you use Ground Improvement? Used correctly Ground Improvement can be used to engineer complex sites, simplify follow on construction and minimise development costs.
Which is the main method of soil improvement?
Dynamic, vibro, grouting, and surcharging represent the primary techniques used to compact or densify soil in situ. Dynamic compaction is most effective in permeable, granular soils, as cohesive soils can absorb and limit the technique's effectiveness.
What is ground improvement work?
Ground improvement, or ground modification, is defined as the alteration of site foundation soils or project earth structures to provide better performance under design and/or operational loading conditions (Schaefer et al., 2012). From: Encyclopedia of Geology (Second Edition), 2021.
Which techniques are used to reduce the soil settlement?
Compacting the soil. Draining the soil, in case of cohesive types. Compacting the soil, in case of cohesion less soils. Confining the soil, increasing stiffness.
What do you mean by soil improvement?
In general, ground/soil improvement is a process carried out to achieve improved geotechnical properties (and engineering response) of a soil (or earth material) at a site.
Which techniques are useful for ground improvement for cohesive soil cohesionless soil and general methods?
Pneumatic Tired Rollers: These rollers are more effective for low cohesive soils and cohesionless soils like Gravels, Sands, Clayey soils, silty sands and even sandy clays. In this technique compaction is due to kneading action.
Which term is need for ground improvement?
Jet grouting is a general term used by grouting contractors to describe various construction techniques used for ground modification or ground improvement.
Why we need ground improvement techniques?
Ground improvement is carried out for various objectives: to improve bearing capacity and reduce settlement of soft ground, prevent earthquake liquefaction, control groundwater, stabilize excavation bottom, prevent deformation of surrounding ground, or clean up contaminated ground.
Why do we ground improvement?
Reasons for ground improvement improve shear strength of the fill and subsoil to ensure sufficient bearing capacity of the foundations and/or sufficient stability of the slopes; increase the density of the fill mass and/or subsoil to prevent liquefaction; and.
What are the different methods used for improvement of ground with loose sand?
Pile driving is one of the most effecting methods for compacting loose sand gravel. The method is also effective in silty soils above the ground water table because of displacement caused by the pile driving. Compaction piles are therefore be used in fine grained soils than can vibroflotation or vibro compaction.
Which is not the method of improving bearing capacity of soil?
INCREASING DEPTH OF FOUNDATION This method of improving bearing capacity of soil is not applicable if the subsoil material grows wetter as depth increase. This method has a limited use because with increase in depth, the weight and cost of foundation also increases.
Which is another type of pre compression pre consolidation of in situ soil method of ground improvement?
Pre-compression It is also known as preloading or surcharging. In this method, the dedicated land area for construction is covered with a surcharge, temporarily before construction. This surcharge is filled upto a suitable height to cause pre-compression of the soil below.
What is the best soil improver?
Compost is my favorite amendment for improving any soil. It makes heavy soil lighter and improves drainage. In sandy soil, it helps retain moisture. And the best part, you can make compost at home for free.
What is soil improvement in agriculture?
Improving soil structure is the key to improving water infiltration into the soil. The maintenance and enhancement of soil organic matter, the use of biosolids or mulch, and conservation and no-till techniques are important strategies for improving soil structure.
What is soil improvement in civil engineering?
Soil improvement in its broadest sense is the alteration of any property of a soil to improve its engineering performance such as strength, reduced compressibility, reduced permeability, or improved ground water condition.
Where is soil improvement needed?
Soil improvement is an alternative considered when the natural soil does not meet the engineering requirements for a project. As an example, if the soil is too weak to carry the structure on a shallow foundation, two alternatives exist: deep foundations or soil improvement plus a shallow foundation.
Pre loading technique of ground improvement - Civil Engineering
Methodology of pre loading:; Before starting the proposed construction the weak soils are improved by applying pre loading technique. The magnitude of the pre load pressure usually rages from 1.2 to 1.3 times of the actual structural pressure or is slightly greater than the maximum pressure that is generated by the proposed structural load.
How can the ground be improved?
The ground can be improved by adapting certain ground improvement techniques. 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. Vibro-replacement stone columns improve the bearing capacity of soil whereas Vibro displacement method displaces the soil. Electro osmosis makes water flow through fine grained soils. Electro kinetic stabilization is the application of electro osmosis. Reinforced soil steel is used for retaining structures, sloping walls, dams etc. seismic loading is suited for construction in seismically active regions. Mechanically stabilized earth structures create a reinforced soil mass. The geo methods like Geosynthetics, Geogrid etc. are discussed. Soil nailing increases the shear strength of the in-situ soil and restrains its displacement. Micro pile gives the structural support and used for repair/replacement of existing foundations. Grouting is injection of pumpable materials to increase its rigidity. The jet grouting is quite advanced in speed as well as techniques when compared with the general grouting. 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 techniques. The field of ground improvement techniques has been recognized as an important and rapidly expanding one.
How is load transferred from the backfill soil to the strip reinforcement?
For walls reinforced with metallic strips, load is transferred from the backfill soil to the strip reinforcement by shear along the interface.
How does vibro compaction work?
Vibro-compaction, sometimes referred to as Vibroflotation, 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. The probe is first inserted into the ground by both jetting and vibration. After the probe reaches the required depth of compaction, granular material, usually sand, is added from the ground surface to fill the void space created by the vibrator. A compacted radial zone of granular material is created
What is preloading soil?
Preloading or pre-compression is the process of placing additional vertical stress on a compressible soil to remove pore water over time.
What is jet grouting?
Jet grouting is a general term used by grouting contractors to describe various construction techniques used for ground modification or ground improvement. Grouting contractors use ultra high-pressure fluids or binders that are injected into the soils at high velocities. These binders break up the soil structure completely and mix the soil particles in-situ to create a homogeneous mass, which in turn solidifies. This ground modification / ground improvement of the soil plays an important role in the fields of foundation stability, particularly in the treatment of load bearing soils under new and existing buildings; in the in-depth impermeabilization of water bearing soils; in tunnel construction; and to mitigate the movement of impacted soils and groundwater. Read More: Ground Freezing Technique for Soil Stabilization -Applications, Advantages Vibro-Stabilization Method of Ground Improvement Ground Improvement Techniques for Stabilization of Subgrade Soils
What is ground freezing?
Ground freezing is the use of refrigeration to convert in-situ pore water to ice. The ice then acts as a cement or glue, bonding together adjacent particles of soil or blocks of rock to increase their combined strength and make them impervious.
What is vacuum consolidation?
Vacuum Consolidation is an effective means for improvement of saturated soft soils. The soil site is covered with an airtight membrane and vacuum is created underneath it by using dual venture and vacuum pump. The technology can provide an equivalent pre-loading of about 4.5m high conventional surcharge fill. Vacuum-assisted consolidation preloads the soil by reducing the pore pressure while maintaining a constant total stress.
What is 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”
What is vegetation as ground improvement?
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.
How does vibration improve soil?
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 ...
How does thermal stabilization improve ground?
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.
What is grouting in soil?
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.
What happens when you put loads on the ground?
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.
What is ground improvement?
Ground improvement and ground modification refer to the improvement in or modification to the engineering properties of soil that are carried out at a site where the soil in its natural state does not possess properties that are adequate to withstand the load of the structure. The improvement may be accomplished by drainage, compaction, preloading, reinforcement, and grouting, electrical, chemical or thermal methods. Among the various soil stabilization procedures, the most suitable one is selected depending upon the type of soil available, time, cost involved etc.
What is soil preloading?
Soil Preloading. Depending on how a preload is applied, the preloading methods can be subdivided into preloading using fill, preloading using vacuum pressure and combined fill, and vacuum preloading methods.
What is MSE soil?
Mechanically stabilized earth (MSE or reinforced soil) is soil constructed with artificial reinforcing. It can be used for retaining walls, bridge abutments, seawalls, and dikes. [ Although the basic principles of MSE have been used throughout history.
How does ISV work?
ISV uses space and an electrical current is passed between them, melting the soil between them. ISV uses very high temperatures (1,600 to 2,000 °C or a pair of, 900 to 3,650 °F). Melting starts close to the bottom surface and moves down. Because the soil melts, the electrodes sink additional into the bottom inflicting deeper soil to soften. Once the facility is turned off, the unfrozen soil cools and vitrifies, which implies it turns into a solid block of glass-like material. The electrodes become a part of the block. This causes the bottom exterior within the space to sink slightly. To level it, the sunken space is full of clean soil.
What is soil vitrification?
Soil Vitrification technique uses heat to melt and then solidify harmful chemicals in a solid mass of glasslike material. It can be applied both in-situ (in-situ vitrification or ISV) and above ground in a treatment unit (ex-situ).
How deep is soil nailing?
Typically, soil is excavated in three to six feet deep stages.
How are stone columns made?
Stone columns are made across the area to be improved in a triangular or rectangular grid pattern. Column depth depends on local soil strata, and usually penetrates weak soil. During construction, a vibrating tool suspended from a crane penetrates to the design depth by means of its own weight and vibrations.
What is ground improvement?
Ground improvementis the procedure typically defined as using mechanical means to improve poor ground conditions. Ground improvement methods improve the engineering properties of the soil mass which is treated to meet project performance requirements. Objectives.
What is the purpose of deep mixing?
The Deep Mixing Method (DMM) is an in-situ modification technique which is performed to improve strength, reduce liquefaction potential, lower permeability, reduce deformations and allow constructio...
Who created the Geotechnical Engineering Photo Album?
Geotechnical Engineering Photo Album: A collection of photographs for educational instruction by Ross W. Boulanger and J. Michael Duncan
What are the two options for building on poor soil?
Historically, when building on sites with poor soils, builders had two primary options to choose from – piling and removal and replacement. While some ground improvement techniques such as dynamic compaction have origins tracing back to the middle ages, it wasn’t until the past half century that ground improvement began to gain wide acceptance ...
What are the three modes of soil improvement?
In general terms, there are three typical modes of soil improvement – densification, reinforcement and drainage enhancement. Some systems provide one of the modes of improvement, while other systems may provide two ...
How does densification work?
Densification is used to improve granular soils such as sand or gravel and is typically achieved by imparting vibration into the ground to prompt the granular soil grains to rearrange into a denser state.
Why are stone columns used?
Stone columns are commonly used to reduce settlement and increase bearing capacity of soils for the support of structures . Because of their high shear strength, they are also commonly used to enhance slope stability and prevent lateral spreading. Stone columns can efficiently mitigate liquefaction resulting from the significant densification of granular layers that occurs during installation; enhanced drainage capacity is also a benefit for liquefaction mitigation. In spite of the versatility of stone columns, slower installation rates and subsequent higher cost of stone columns deeper than about 40 feet make their use for deeper soils less viable. Stone columns are also not applicable for very soft clays or organic soils where the columns would be prone to bulging which would lead to excessive settlement or even failure.
How does dynamic compaction work?
Dynamic compaction uses large crawler cranes to drop weights that typically range from 10 to 20 tons repeatedly in a predetermined grid pattern to increase density and reduce voids in granular soils, fills, and landfill materials. Most effective for large-footprint sites, the technique is less effective in overly clayey or silty soils and where shallow groundwater is present. Because of the large amount of vibration introduced into the ground, special care should be taken when using dynamic compaction near utilities, buildings, or other vibration- or settlement-sensitive structures. A related technique, Rapid Impact Compaction (RIC) is used to compact soils when it is necessary to limit vibrations. RIC typically treats a shallower depth of soil and is performed using a pile-driving hammer that is mounted to the front of an excavator to pound a steel plate seated on the ground surface.
What is an earthquake drain?
These drains are designed to alleviate pore pressure build up during seismic events such as earthquakes, and reduce both the likelihood of liquefaction occurring and the amount of liquefaction-induced settlement that occurs. The drains are typically comprised of a 4-in-diameter slotted, flexible, corrugated pipe encased in a geotextile fabric. The drains are driven into the ground at spacings that typically range from 5 to 10 ft.
What is preload soil?
In the simplest terms, a preload consists of a pile of soil that exerts stresses on the receiving ground that are similar or greater than the stresses that the ground will receive from the planned structure. As the preload remains in place, the underlying soil layers are squeezed and compressed.
What is ground improvement?
Ground improvements are done specially for shallow foundations when they are constructed in weak soils. Based on the classification of soil under the foundation, the type of improvement is selected. The type of loadings will also be taken into account when the improvement technique is finalized. There are many methods for ground improvements.
What are the advantages of granular fill?
The use of this method provides more advantages such as the compact large area of loose granular fill, reduce the volume of landfill waste, increase the density and bearing capacity of the soil and reduces the post-construction settlements.
When can grout be injected into oil?
When there is weak ground with sufficient permeability for flowing the grout , grout can be injected into the oil for improving its bearing capacity. This could be done as recommended by the geotechnical engineer. There are different grouting methods used in the industry especially in shallow depths.
What is grouting used for?
Grouting is more commonly used as a ground improvement method for foundation work especially infrastructure projects such as the construction of dams. Even for building construction, this method can be applied when there is a grout taking soil.
Why is grout used in dams?
In large infrastructure projects like dams, grout is used to fill the cavities in the rock and to decrease the permeability. As a result of grout filling, cohesion and shear strength will increase.
What is vacuum consolidation?
Vacuum consolidation is a ground improvement technique used for soft soils. It is a process of applying vacuum pressure on the soil which is protected from the surface from losing the pressure by a sealing membrane.
Why is loose ground vibrated?
In this method, the loose ground is vibrated to change the configuration of the soil to dense form. Due to the high vibration, soil particles are rearranged to the configuration that reduces the void ratio and increases the density. This method is more suitable for sandy soils.
How can the ground be improved?
The ground can be improved by adapting certain ground improvement techniques. 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. Vibro-replacement stone columns improve the bearing capacity of soil whereas Vibro displacement method displaces the soil. Electro osmosis makes water flow through fine grained soils. Electro kinetic stabilization is the application of electro osmosis. Reinforced soil steel is used for retaining structures, sloping walls, dams etc. seismic loading is suited for construction in seismically active regions. Mechanically stabilized earth structures create a reinforced soil mass. The geo methods like Geosynthetics, Geogrid etc. are discussed. Soil nailing increases the shear strength of the in-situ soil and restrains its displacement. Micro pile gives the structural support and used for repair/replacement of existing foundations. Grouting is injection of pumpable materials to increase its rigidity. The jet grouting is quite advanced in speed as well as techniques when compared with the general grouting. 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 techniques. The field of ground improvement techniques has been recognized as an important and rapidly expanding one.
How is load transferred from the backfill soil to the strip reinforcement?
For walls reinforced with metallic strips, load is transferred from the backfill soil to the strip reinforcement by shear along the interface.
How does vibro compaction work?
Vibro-compaction, sometimes referred to as Vibroflotation, 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. The probe is first inserted into the ground by both jetting and vibration. After the probe reaches the required depth of compaction, granular material, usually sand, is added from the ground surface to fill the void space created by the vibrator. A compacted radial zone of granular material is created
What is preloading soil?
Preloading or pre-compression is the process of placing additional vertical stress on a compressible soil to remove pore water over time.
What is jet grouting?
Jet grouting is a general term used by grouting contractors to describe various construction techniques used for ground modification or ground improvement. Grouting contractors use ultra high-pressure fluids or binders that are injected into the soils at high velocities. These binders break up the soil structure completely and mix the soil particles in-situ to create a homogeneous mass, which in turn solidifies. This ground modification / ground improvement of the soil plays an important role in the fields of foundation stability, particularly in the treatment of load bearing soils under new and existing buildings; in the in-depth impermeabilization of water bearing soils; in tunnel construction; and to mitigate the movement of impacted soils and groundwater. Read More: Ground Freezing Technique for Soil Stabilization -Applications, Advantages Vibro-Stabilization Method of Ground Improvement Ground Improvement Techniques for Stabilization of Subgrade Soils
What is ground freezing?
Ground freezing is the use of refrigeration to convert in-situ pore water to ice. The ice then acts as a cement or glue, bonding together adjacent particles of soil or blocks of rock to increase their combined strength and make them impervious.
What is vacuum consolidation?
Vacuum Consolidation is an effective means for improvement of saturated soft soils. The soil site is covered with an airtight membrane and vacuum is created underneath it by using dual venture and vacuum pump. The technology can provide an equivalent pre-loading of about 4.5m high conventional surcharge fill. Vacuum-assisted consolidation preloads the soil by reducing the pore pressure while maintaining a constant total stress.
Ground Improvement by Vibration
Ground Improvement by Adding Load Or Increasing Effective Stress
Ground Improvement by Structural Reinforcement
Ground Improvement by Structural Fill
Ground Improvement by Admixtures
Ground Improvement by Grouting
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 w...
Ground Improvement by Vegetation