Page 18 - Building Regulation and Design Guidelines - Structural (Grey Code)
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SECTION: 1 GEOTECHNICAL GUIDELINES & REGULATIONS SECTION: 1 GEOTECHNICAL GUIDELINES & REGULATIONS
1.3.6 SHALLOW FOUNDATIONS
- The foundation level should be in compliance with the architectural
requirements. 1 PILE 2 PILE 3 PILE 4 PILE 5 PILE 6 PILE
- Net allowable bearing pressure to be determined considering
shallow foundations at the foundation level using practical
experience and the results obtained from the field standard 7 PILE 8 PILE 9 PILE 10 PILE
penetrations tests, the empirical equations developed by Terzhagi
- Peck/Merehof and modified by Bowles considering a proper FOS
against shear failure of the soil.
11 PILE 12 PILE 13 PILE
- Using the calculated allowable bearing pressure value, the total
settlement for isolated/strip footing and raft foundation shall be
within 25mm & 50mm respectively. The differential settlements
should be indicated.
14 PILE 15 PILE 16 PILE
- The proposed foundation recommendations must ensure that an
adequate safety factor against likely uplift pressure established Fig. (1.15): Piles Distribution
based on selected Design GW level is satisfactory to local authority
and / or project requirements particularly when basement floor(s) - The geotechnical report shall include an estimate of single pile vertical
exist. and lateral stiffness for the adopted pile cut off levels and penetration
depths. Lateral stiffness shall be based on cyclic conditions. The
- Modulus of sub-grade reaction ks (kN/m3) shall be indicated in the assessment of pile group effects on vertical and lateral stiffness shall
soil report when the raft foundation is recommended. be performed by the foundation design Engineer.
- The foundation ground must be proof rolled with vibratory - For bored cast-in-situ piles, settlements of the order of 1% of the pile
compactor to confirm that any loose materials are compacted to not diameter is normally required to mobilize full skin friction whereas
less than 95% of the maximum dry density obtained by performing full bearing is developed at much higher settlements (usually at 10%
modified Procktor test. of pile diameter). Therefore, it is recommended that the pile capacity
shall be based on full skin friction and partial end bearing.
- The specialist should confirm in writing that the undesirable
materials have been removed, the foundation ground has been - Where the borehole depth is not satisfactory for the design,
inspected and the recommended bearing capacity corresponding to additional boreholes should be carried out to the required depth to
the foundation depth is properly achieved. reconfirm the continuity of the strata. Fig. (1.15): Piles Distribution
1.3.7 PILE FOUNDATIONS 1.3.8 FOUNDATION CONCRETE
- The soil report should propose the suitable type of pile to be Concrete mix design should consider strictly the chemical analysis data
used, the allowable working loads in compression and tension for both soil and water and to be in line with Trakhees Construction
considering minimum factor of safety of 2.5. Piles spacing should Materials Quality Control Guidelines.
be recommended in the piling recommendations Minimum 2.5 the
pile diameter, Fig. (1.15). It should be noted that the minimum pile 1.3.9 LIQUIFACTION:
toe level should be at least at depth of two times the diameter of
pile socketed in the hard strata in order to consider this strata in The likely liquefaction induced effects are:
the design. - Settlement.
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