SHORT POINTS FOR GROUND FREEZING

1. GROUND FREEZING
BY
AVINASH KUMAR PANDEY

2. CONTENT
• Introduction
• Purpose
• Process
• Characteristics
• Advantages
• Application
• Conclusion

3. INTRODUCTION
• To change the water in the soil into solid wall of ice, which is
completely impermeable. Water inflow can cause enormous
problem in excavation and tunneling projects so the best way
to stop water is to freeze it.
• Frozen ground is twice as strong as concrete and it is
essentially impermeable.

4. PURPOSE
• Groundwater cutoff
• Earth support
• Temporary underpinning
• Stabilization of Earth for tunnel excavation
• Arrest landslides
• Stabilize abundant mine shafts

5. Process
• It is analogous to pumping ground water from wells.
• Arrow of freeze pipes placed vertically in the soil and heat
energy is removed through these pipes using chilled brine.
• Isotherms move out from freeze pipes with time.
• Water in soil pores turns to ice at 32°F
• In granular soil, ground water in pores freezes readily. Further
decrease in temperature increases strength marginally.
• In cohesive soil, below freezing temperature ,only some
portion of pore water freezes to stiffen the clay. Further
reduction in temperature enables it to gain more strength.
• A temperature of +20°F may be sufficient in sand, whereas -
20°F may be required in soft clay.

7. • Formation of frozen Earth barrier is governed by thermal and
hydraulic properties of each stratum. Typically, rock and
coarse-grained soils freeze faster than clays and silts.
• The frozen earth first forms in the shape of vertical cylinders
surroundings the freeze pipes.
• As cylinders gradually enlarge they intersect, forming a
continuous wall. Once the design thickness is achieved freeze
plant is operated at a reduced rate.

8. CHARACTERISTICS
• Not limited by soil types irrespective of complex geologic and
hydrological conditions.
• Strength of freezing soil can be controlled.
• Equipment can be recycled and reused.
• No frost heaving and freezing-thawing settlements for gravel
soil whereas for fine grained soil settlements are predictable.
• Can be used in congested areas.
• Method is relatively fast

9. ADVANTAGES
• Lesser risk to surrounding structures particularly in built-up
areas.
• No shuttering is required.
• Environment friendly process.
• Unlimited depth can be frozen from the surface.
• Can be removed easily and completely.
• Allows frozen soil barriers can be easily monitored.
• Can be used either for temporary containment or as long term
barrier.
• It freezes loose ,wet sand to prevent liquefaction during an
earthquake.
• It bonds soil and waste together to prevent dangerous mixing
during removal

10. APPLICATION
• Circular excavation supported by freeze wall
• Excavation supported by gravity wall of frozen earth
• Shaft sinking
• Tunnels and subways

11. CONCLUSION
• The viability and versatility of ground freezing for
construction purposes is thus demonstrated through this
presentation including few case studies along with mentioning
of some of its many applications. In addition, given that the
current interest in ground freezing is becoming increasingly
focused on environmental remediation.