Subsoil improvements
Contents |
[edit] Introduction
Many techniques are available to improve subsoil. The aim of soil improvements can be:
- To increase its bearing capacity by improving the shear strength.
- To enhance the soil stiffness and density so that liquification can be avoided.
- To prevent excessive settlement, in particular in the construction of roads, runways and so on.
- To stabilise or immobilise contaminants within the soil.
Some of the available techniques are described below.
[edit] Land drainage
The purpose of this method is to lower a high-water table and to dry out the ground to improve its bearing capacity. The technique might involve water entering into a flexible perforated drainage pipe in the ground and being directed away. A layer of shingle might be added to assist.
[edit] Grouting
Soft subsoil is a serious problem for maritime construction. A solution can be to inject a cement-based mixture into the subsoil under pressure. The mixture will expand and fill any voids and eventually form a strengthened base with improved the permeability.
For more information see: Grouting.
[edit] Vibroflotation
A vibrating probe is lowered into the ground by vibrating jets causing vibration. After the probing process is complete a granular hardcore mixture is poured into the hole and further compacted by the probe. Once the probe is slowly removed, further hardcore is pushed in until a column is formed. This process requires specialist plant and cranes.
[edit] Compaction with rollers
Plant rolling machinery is used to compact soil.
For more information see: Roller
[edit] Dynamic compaction
A method that is used to increase the density of soil deposits. The process uses specialist plant and cranes to drop a heavy weight repeatedly on the ground at consistent intervals.
[edit] High energy impact compaction
A method that is used in low strength soils. Specialist plant is used with big hexagonal-shaped rolling attachments in a controlled dynamic drag along site.
[edit] Vacuum consolidation
Prefabricated vertical drains were originally used with surcharge fill to manage residual settlement in soft ground. This method was extended to include vacuum application for better results. This method uses stress transfer and surface loading techniques and is carried out by specialist contractors.
[edit] Geotextiles
Geotextiles are permeable fabrics that can be used to filter, reinforce, separate, drain or protect. They work by allowing filtration or separation of granular layers in-ground applications. They are commonly used in construction and are a relatively easy way to improve soil characteristics.
For more information see: Geotextiles.
[edit] Related articles on Designing Buildings Wiki
- Alluvium.
- Bearing capacity.
- Geotextiles.
- Groundwater.
- Grouting.
- Insitu testing of soils.
- Roller.
- Soil compaction.
- Soil survey.
- The importance of soil analysis.
- Types of soil.
- Vibro-compaction for ground improvement.
- Water table.
[edit] External references
BTEC National Construction - Pearson
Featured articles and news
Government consultations for the summer of 2025
A year of Labour, past and present consultations on the environment, the built environment, training and tax.
CMA competitiveness probe of major housing developers
100 million affordable housing contributions committed with further consultation published.
Homes England supports Greencore Homes
42 new build affordable sustainable homes in Oxfordshire.
Zero carbon social housing: unlocking brownfield potential
Seven ZEDpod strategies for brownfield housing success.
CIOB report; a blueprint for SDGs and the built environment
Pairing the Sustainable Development Goals with projects.
Types, tests, standards and fires relating to external cladding
Brief descriptions with an extensive list of fires for review.
Latest Build UK Building Safety Regime explainer published
Key elements in one short, now updated document.
UKGBC launch the UK Climate Resilience Roadmap
First guidance of its kind on direct climate impacts for the built environment and how it can adapt.
CLC Health, Safety and Wellbeing Strategy 2025
Launched by the Minister for Industry to look at fatalities on site, improving mental health and other issues.
One of the most impressive Victorian architects. Book review.
Common Assessment Standard now with building safety
New CAS update now includes mandatory building safety questions.
RTPI leader to become new CIOB Chief Executive Officer
Dr Victoria Hills MRTPI, FICE to take over after Caroline Gumble’s departure.
Social and affordable housing, a long term plan for delivery
The “Delivering a Decade of Renewal for Social and Affordable Housing” strategy sets out future path.
A change to adoptive architecture
Effects of global weather warming on architectural detailing, material choice and human interaction.
The proposed publicly owned and backed subsidiary of Homes England, to facilitate new homes.
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.