1. Modern GROUND IMPROVEMENT TECHNIQUES FOR HIGHWAYS

2. INTRODUCTION Transportation contributes to the economic,industrial,social and cultural development of any country. Transportationby road or highways is the only mode which could give maximum service to one and all. When the soil on a project site cannot support the loads, ground improvement to increase strength, reduce compressibility, and enhance performance under applied loadings may be required. The field of ground improvement techniques has been recognized as an important and rapidly expanding one. Various methods are discussed below:

3. METHODS FOR GROUND IMPROVEMENT 1. VERTICAL DRAINS 2. SOIL NAILING 3. STONE COLUMNS 4. VIBRO COMPACTION 5. DYNAMIC COMPACTION 6. VIBRO PIERS

4. VERTICAL DRAINS These consist of a column of pervious material placed in cylindrical vertical holes at sufficiently close spaces. All drains should be connected at the ground surface to a drainage blanket. Vertical drains accelerate consolidation by facilitating drainage of pore water. Vertical drains are laid out in rows, staggered, or aligned to form patterns of equilateral triangles or squares. Two types of drains are discussed below

8. APPLYING SHOTCRETE HOLES DRILLED THROUGH MACHINES

9. SOIL NAILING

11. The vibrator first penetrates to the required depth by vibration and air or water jetting or by vibration alone.

12. Gravel is then added at the tip of the vibrator and progressive raising and repenetration of the vibrator results in the gravel being pushed into the surrounding soil.

15. VIBRO COMPACTION It is a ground improvement process for densifying loose sands to create stable foundation soils. The action of the vibrator, usually accompanied by water jetting, reduces the inter-granular forces between the soil particles, allowing them to move into a denser configuration, typically achieving a relative density of 70 to 85 percent. Compaction is achieved above and below the water table.

16. PROCESS OF VIBRO COMPACTION

17. DYNAMIC COMPACTION Dynamic Compaction is the dropping of heavy weights on the ground surface to densify soils at depth. It involves the repeated dropping of large steel tampers by means of crawler cranes. Tampers typically range from 6 to 20 tons and are dropped from heights of about 40 to 80 feet.

18. MACHINE WITH TAMPER COMPACTION BY TAMPER

19. VIBRO PIERS Vibro Piers, also known as aggregate piers, are typically installed to intermediate depths of 5 to 20 feet for the support of new loads. Vibro Piers are quick to install and very effective at reinforcing the surrounding soil. Typical Vibro Pier construction begins with pre-drilling a full-depth hole with a diameter that is equal to the final pier design diameter. For soils in which the pre-drilled hole will not stay open, the bottom feed process can be used to avoid the need for casing.

20. BOTTOM FEED PROCESS AGGREGATE INTRODUCED THROUGH PREDRILLED HOLES

21. CONCLUSION Though the term Ground Improvement has been familiar to Civil Engineers, the design approach is still empirical, mostly based on past experience. The Importance of Ground Improvement is immeasurable. Ground stability is a vital part of any construction project. Method adopted to be applied on the field should be according to site condition and economical. Application of Ground Improvement Techniques is not only cheaper but also reduce the construction time significantly. Ground improvement technique also plays a vital role in the development of our mother land by 2020.

22. REFERENCES K.R.Arora, (2005)"Soil Mechanics and Foundation Engineering", Standard Publishers Distributors, Delhi. www.haywardbaker.com . TerraSystems(Geotechnical Contracting Firm) . www.google.com Rembco Geotechnical Contractors Inc.

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