1. Module-1 Introduction to Ground Improvement Techniques
By: Dr. Madhavi T
Assistant Professor,
Department of Civil Engineering
Presidency University, Bengaluru
2. Contents:
• Need for Ground Improvement
• Objectives
• Soils of India
• Factors affecting selection of Ground Improvement techniques
• Classification of Ground Improvement Techniques
• Emerging trends in Ground Improvement Techniques
9. Introduction
• The large-scale growth of population, industrialization and modernization over the last few decades has
resulted in unprecedented magnitude of construction activities in the world.
• The construction sites are now made on the basis of functional and locational considerations rather than on
their suitability from the perspective of geotechnical engineering.
• With the growth of cities and industries, the availability of so-called good and strong sites is becoming rare.
Hence, the poor quality of the given construction sites is mounting pressure on the involved engineers to
find suitable, safe and cost effective methods of design and construction.
• Very often, engineers encounter the situations where soil investigation reports from the site reveal the
unsuitability of the ground for conventional construction. The sites are underlain by weak and difficult soft
soils of low strength, high compressibility or other undesirable characteristics.
• Such soft soils are often found in the alluvial plains, coastal areas, along the perimeter of bays and beneath
the wetlands.
• At present, neither the question of selecting alternate suitable site for the project arises nor there can be
any option of minimizing the design loads. Thus, the only option left to engineers is to adopt method of
forcing the weak sub soil to behave according to the project requirement rather than to reject the site.
10. Introduction
The term ‘ground improvement’ and ‘ground modification’, refer to the
improvement or modification to the engineering properties of a soil
that are carried out at a site where the soil in its natural state does not
possess properties acceptable for the proposed civil engineering
activity.
11. Need for ground improvement techniques
Where a project encounters difficult foundation conditions, possible alternative
solutions are:
• Avoid the particular site - Relocate a planned highway or development site.
• Design the planned structure accordingly - Some of the many possible approaches are to use a
raft foundation supported by the piles, design a very stiff structure which is not damaged by
settlement, or choose a very flexible construction which accommodates differential movements
or allows for compensation. The solution will depend on the geotechnical performance criteria
stipulated, which generally relate to stability, deformation and/ or seepage.
• Remove and replace unsuitable soils – Removing organic top soil, which is soft, compressible, and
volumetrically unstable, is a standard precaution in road or foundation construction.
• Attempt to modify the existing ground.
• Enable cost effective foundation design.
• Reduce the effects of contaminated soils.
• Ensure sustainability in construction projects using ground improvement techniques.
12. Objectives
• Increase strength, reduce erodability
• Reduce distortion under stress
• Reduce compressibility.
• Control shrinkage and swelling.
• Control permeability, reduce water pressure, and redirect seepage.
• Prevent detrimental physical or chemical changes due to environmental
conditions (freezing or thawing).
• Reduce susceptibility to liquefaction.
• Reduce natural variability of foundation soils.
