SOIL NAILING

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SOIL NAILING GUNITING

• Presented By
• MUHAMAD NAJIB BIN MOKHTAR (IR. DR. NAMOUSII)

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Contents

• Basic Knowledge
• At Construction Site
• Conclusion

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1.1Basic Knowledge
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Soil Nailing In Slopes Stabilization

• Proven cost, used to cut slopes or to support
  deep excavation by reinforcing the insitu ground.
  (Drilling, inserting bar, grouting and nail head
  construction/ facing/ guniting.)
• Pull-out resistant of the reinforcing element.
• Practice estimated based on soil data with
  reference to empirical observations.
• On site pull-out test result derived from full
  scale verification/ sacrificial tests.

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Soil Nailing In Slopes Stabilization

• Some slope movement is required to mobilize load
  tension in the soil nail (up to 30mm).
• Lateral displacement due to stress-relief of
  excavated steep soil nailed slope/ wall is about
  0.1-0.3H.
• When lateral deformation exceed 0.5H, excessive
  bending and shear in soil nails may happen,
  resulting in excessive creep and tension cracks
  in upslope or eventual slope failure, if left
  unattended.

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Soil Nailing In Slopes Stabilization

• Soil nails need to extend to sufficient length
  beyond the active zone or any plane of weakness
  to overcome external stability including
  overturning, sliding, bearing and overall slope
  instability, modes of failure.
• Three internal failure modes must be checked to
  ensure an adequate factor of safety, i.e. nail
  pull-out resistance, nail material tensile
  capacity and nail head/ facing capacity.

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1.2Construction Site
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Drilling Method

• Characteristics
• Constant straight diameter
• Stable drill hole
• Drilling debris wholly
• Cleanly removed are achievable.
• The rotary percussion method
• Using top hammer or down-the-hole hammer
• Capable of completing the drill hole within a
  short time (lt1hour) should normally used.

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Drilling Method

• Observation of the drill log
• Location
• Time/ duration
• Soil type/ strata
• Changes in penetration rate/ sound
• Flushing characteristics (wetness, color, nature
  and sizes of cutting)

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Installation Of Reinforcement Bar

• For permanent works, rebars should be protected
  against corrosion by hot-dip galvanizing (BS729)
  with a minimum coat thickness of 85microns or
  610gm/m2.
• Rebars only need to be protected in corrugated
  HDPE stealth for cases of proven aggressive soil
  (pH value lt4.5 or sulphate gt200ppm or chlorite
  content gt100ppm.)

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Installation Of Reinforcement Bar

• Centralizers should be made from galvanized steel
  or other suitably high quality material
  dimensioned to fit the rebar at the centre of the
  hole whilst not obstructing passage of cement
  grout pipe.

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Nail Head

• Guniting facing
• HDPE Geocell slope
• protection system
• Grid beam system

For green vegetative slope landscape
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Guniting

• Mixture of cement, sand and water.
• Projected pneumatically at high velocity from a
  suitable nozzle onto the slope surface.
• Weep hole pipes, spacers and dowels
• Should be firmly and securely fixed /anchored
• Must be adequate and not disturbed /distorted
  /deformed /blocked during the guniting process.

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1.3Conclusion
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Soil Nailing and Guniting

• Must take seriously in making soil nailing and
  guniting.
• Avoid side slopes and accidents caused by side
  slopes.
• Dont only depend on study but adopted site
  practices.