Page 26 - Building Regulation and Design Guidelines - Structural (Grey Code)

SECTION: 1 GEOTECHNICAL GUIDELINES & REGULATIONS SECTION: 1 GEOTECHNICAL GUIDELINES & REGULATIONS

cracking and sand boils (Ishihara, 1985) is based on the not pause a threat to the personnel working on site or cause any damage to
thickness of the potentially liquefiable layer and the thickness nearby existing buildings or roads. Fig. (1.33) shows the method statement
of the non-liquefiable crust. for contiguous, secant and soldier piles shoring systems.

1.4.4.c Loss of bearing capacity for shallow foundation:
As per the Implementation Committee, the loss of bearing
capacity may be significantly occurred if the induced vertical Installation of Casing Augering of Borehole Concreting of Borehole
stresses on liquefiable layer located at certain depth exceeds
10% of the bearing pressure imposed by the foundation. There
is no recognized analytical method to evaluate the loss of
bearing capacity at this time.
The Committee recommends that Ishihara’s method of surface
manifestation analysis to be used for shallow foundations.

1.4.4.d Loss of lateral soil stiffness:
Loss of lateral soil stiffness has a greater impact on the design
of piling and shoring works. The negative skin friction for the
untreated fill layer shall be considered in determination of Fig. (1.33-a). Contiguous Piles Shoring System
the pile capacity. The pile shall be considered unconstrained
along the untreated layer in both vertical and lateral analysis.
Lateral load to be considered due to ground motion from an
earthquake of a=0.225g at ground level or 0.15g at cap rock
level.
Augering of Secondary Borehole
Installation of Casing Concreting of Secondary Borehole
1.4.4.e Lateral spreading or land sliding:
Such spreads can occur on gently sloping ground or where
nearby drainage or stream channel can lead to static shear
biases on essentially horizontal ground (Youd, 1995).
Construction
of Guide wall
1.4.5 LATERAL EXTEND OF GROUND IMPROVEMENT
To mitigate the liquefaction hazards, the treatment of the fill material
shall be extended laterally by two-thirds the liquefiable layer thickness
beyond the whole building foundation limits, (Lai 1988).
Fig. (1.33-b): Secant Piles Shoring System
1.5 SHORING GUIDELINES

a) For neighbouring shallow foundation or for excavations deeper than 1.50
m, suitable side protection have to be ensured so that the excavation shall

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