In its broadest sense, the term soil improvement refers to the alteration of any one of its properties for improving its engineering performance, such as reduced compressibility, strength, improved ground water condition or reduced permeability. This could be a temporary procedure for permitting the construction of a structure or could be a permanent one for improving the performance of the completed structure. Depending on the type of soil and construction activity, there are numerous techniques that can be used for improving the soil. Some of the top techniques that can be used are:
Surface compaction
This is one of the oldest methods that are used for soil densification. A compacted base is required when a new embankment, road or runway is being constructed. This is also true for a loose site as the only way a structure can be laid down is on a compacted base. If there is little depth to be densified, surface compaction alone is enough for solving the problem. Tampers, rollers and rammers are the commonly used surface compaction devices. It is also possible to use conventional rollers, such as grid, vibratory, sheep foot, rubber-tyred or smooth wheel rollers.
Drainage methods
One of the most difficult problems that are faced by construction companies in excavation work is ground water. The pore water pressure is increased by the presence of water and it can decrease the shear strength. Erosion may occur when the excavation receives heavy inflow of water and the open excavations may also collapse as a result. There are certain methods that can be used for controlling the ground water and ensuring an economical and safe construction scheme. Some of the common drainage methods that can be used are vacuum dewatering system, well-point systems, dewatering by electro-osmosis and deep-well drainage.
Vibration methods
When saturated non-cohesive soils have to be rapidly densified, the vibration methods can come in handy. Shock waves and vibrations in loose deposits of these materials can lead to liquefaction. When the excess pore water pressure dissipates, densification occurs. Some of the popular vibration methods that are used by construction companies nowadays are heavy tamping, vibratory rollers, vibrating probe for installing vibro stone columns, vibro-displacement compaction piles etc.
Pre-compression and consolidation
As the name indicates, the purpose of this method is to consolidate the soil before construction begins. There are different techniques that can be used, such as vertical drains, preloading and surcharge fills, electro osmotic consolidation and dynamic consolidation.
Grouting and injection
The injection of stabilizers, either in the form of suspension or solution, into the subsurface rock or soil is referred to as grouting. It is performed for one of the following reasons:
- Filling the void for preventing excessive settlement
- Strengthening the soil for reducing lateral support requirements
- Reducing the vibrations of machine foundation
- Controlling ground water during construction
- Stabilizing loose soils against the risk of liquefaction
- Strengthening adjacent foundation soils for protecting them against any damage during excavation.
Suspension grouts are used for grouting including with soil, cement, lime and whereas solution grouts are one-shot or two-shot systems.
You must be logged in to post a comment.