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Advanced Foundation Engineering
Chapters 10-11
and 16
According to the Dubai building code
Professor. Dr.Abdoullah Namdar
Email; ab_namdar@yahoo.com

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Suitable geotechnical design
Reference, Dubai Building Code, UAE

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The minimum geotechnical requirements are
related to;
1- geology, 2 - stratigraphy, 3 - geotechnical
4 - groundwater.
A major characteristic of the ground in Dubai
• Calcareous sand
• Soft calcareous rocks, with
• Clay minerals of various expansion potentials.
Groundwater is saline with chlorites and sulfates
that make a very aggressive environment for
concrete and reinforcement in the ground.

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Geotechnical site investigation
a) to assess the general suitability of the site for
the proposed works;
b) to enable an adequate and economic design
to be prepared;
c) to foresee and provide against difficulties
that may arise during construction due to
ground and local conditions
d) to predict any adverse effect of the proposed
construction on neighboring structures.

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Planning geotechnical investigation
a) the location of the building;
b) the magnitude of the imposed loads;
c) the number of floors;
d) the shape of the building;
e) previous uses of the land;
f) terrain surface features;
g) geological features; and
h) surface water drainage.

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a) non-intrusive investigations
(mapping, geophysics);
b) intrusive investigations (boreholes,
trial pits, observation wells);
c) sampling of soils, rocks, and
groundwater;
d) in-situ testing including:
1) standard penetration test
(SPT);
2) cone penetration test (CPT);
3) pressure meter;
4) permeability;
5) in-situ strength;
6) deformability
Geotechnical on-site investigations

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Depth of investigation
The depth of investigation shall extend to at least three times the
shortest plan dimension of the proposed foundation
The minimum number of boreholes shall conform
to1) for high-rise buildings: more than G+12, one borehole per 750
m2
and a minimum of five boreholes;
2) for buildings: less than G+12, one borehole per 750 m2
and a
minimum of three boreholes; and
3) for large structures: 60 m grids between boreholes are required.

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The requirements for geotechnical soil
investigations
a) soil classification/index tests;
b) soil engineering properties tests (strength, stiffness,
deformability);
c) rock classification/index tests;
d) rock engineering properties tests; and e) soil, rock, and
groundwater chemical tests.
Soil tests shall be conducted in laboratories licensed and approved
by the EIAC. All soil tests shall conform to EIAC approved
standards.

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The GIR shall include the following details as a minimum when submitted to the
Authority:1) details of the recommended foundation system, with allowable bearing
capacity, modulus of sub-grade reaction and allowable settlement;
2) provision to mitigate the effects of expansive and collapsible soils in
accordance with the recommendations provided in Ch. 32 and 33 of the ICE
Manual of geotechnical engineering (vol. I) [Ref. F.20];
3) provision to mitigate the effect of soil liquefaction, which shall be assessed as
stipulated in F.9.4.5;
4) provision to mitigate the effect of soil settlement and loads from adjacent
plots;
5) various seismic parameters for the uppermost 30 m, in accordance with the
specified codes;
6) piles working load capacity under compression and tension for different sizes,
at varying depths and effective length (all levels should be in DMD);
7) if applicable, recommendations for pile groups with modification factors for
load and settlement;
8) values of modulus of elasticity of soil (Es);
9) horizontal modulus of sub-grade reactions (Kh);
10) constant of horizontal sub-grade reaction (nh);
11) vertical spring constants (Kv);
12) Poisson’s ratio;
13) piles stiffness (Ks);
14) optimal spacing between piles within a pile group;

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15) soil parameters required for shoring and basement wall design, such
as: i) average bulk density; ii) angle of shearing resistance; iii) cohesion;
iv) coefficients of soil pressure at rest (K0) pressure; and v) coefficient of
active and passive soil pressure for all soil layers.
16) soil classification and index test results (particle size distribution,
plasticity chart);
17) rock classification and index test results;
18) permeability of soil and rock layers;
19) plan showing boreholes, in-situ test location and coordinates;
20) water table level (in DMD) and temperature;
21) laboratory test results on soil and groundwater samples for the
presence and concentration of pH, sulfate, and chloride, or any other
chemicals or components that might affect the structure;
22) type of cement based on the chemical test results of soil types;
23) summary of soil parameters;
24) subsoil conditions and description;
25) recommendation on the earthwork, excavation, filling, and
compaction;
26) recommendations for suitability of site material to be used as fill
material.

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The list below presents some of the common slope stabilization
techniques.
a) Regrading of the slope. If the available land plot permits, the slope can
be regraded to reduce the slope angle.
b) b) Drainage. Deep drains are perforated plastic tubes that can be
embedded into the slope to reduce the pore water pressure.
c) Retaining wall. Retaining walls shall be designed.
d) Soil nailing. The soil nails are secured to steel plates at the surface and
optional erosion and vegetation control geosynthetic mesh can be
placed over the slope face. If the soil is loose on the surface, concrete
can be sprayed to cover the slope face.
e) Filling material. The material used for backfilling purposes shall be of
selected fill composed of a sand/granular mixture. The plasticity index
of the backfill material should not exceed 10%. The maximum particle
size of backfill material shall not exceed 75 mm. The percentage
passing through a 75 mm sieve shall not exceed 20%. The organic
materials content shall not exceed 2% and the water-soluble salt
content shall not exceed 5%.
f) Compaction. The backfill materials shall be placed in layers of thickness
150 mm to 250 mm and compacted to not less than 95% of the
maximum dry density. The Engineer shall state whether the material
available on site could be used for general backfilling or not after
performing the necessary analysis.

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Shallow and raft foundations
The most common limit states for spread foundations
are:
a) loss of overall stability;
b) bearing resistance failure;
c) failure by sliding;
d) combined failure in the ground and the structure;
e) structural failure due to foundation movement;
f) excessive settlements;
g) excessive heave due to swelling, frost, and other
causes;
h) unacceptable vibrations.

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The design of deep foundations:
a) loss of overall stability;
b) bearing resistance failure of the pile foundation;
c) uplift or insufficient tensile resistance of the pile foundation;
d) failure in the ground due to transverse loading of the pile
foundation;
e) structural failure of the pile in compression, tension, bending,
buckling, or shear;
f) combined failure in the ground and the pile foundation;
g) combined failure in the ground and the structure;
h) excessive settlement;
i) excessive heave;
j) excessive lateral movement;
k) unacceptable vibrations;
l) liquefaction effects on piles. The load-bearing mechanism (i.e. end
bearing, friction, friction with end bearing piles) shall be
recommended in the GIFR.

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Crack width limit for tension piles (wk)
0.2 mm considering the tension load.
0.1 mm considering the uplift load due to permanent tension load (i.e.
groundwater uplift, out-of-balance gravity loads).
For Pile design
 Minimum bar diameter; 12mm
 Minimum number of bars; Six bars evenly spaced.
 Minimum stirrup reinforcement; Bars of 10 mm diameter for all the piles.
 Minimum pile spacing shall be 2.5 times the diameter.
 For Pile stress under compression load; Maximum 25% of concrete streng
 For Lateral stiffness of piles; 50% to 100% of vertical stiffness.
 The factor of safety shall be at least 2.5 unless geotechnical model and
geotechnical calculations based on the geotechnical site investigation are
provided.

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For the lateral pile design, the following requirements shall be included:
a) minimum 5% of pile capacity and not less than the horizontal loads
resulting from the superstructure and foundation analysis;
b) b) moments due to out of position (75 mm) piles; and
c) c) horizontal force due to verticality (1/75).
The above design (a) may be excluded if geotechnical calculations and
geotechnical models are provided and the following items are included in
the design:
1) isolated temperature changes within raft, and temperature
distribution from column to raft;
2) detailed pile group assessment considering soil-structure interaction,
building stiffness and foundation stiffness;
3) moments due to slab dishing;
4) kinematic effects of earthquake loading;
5) sensitivity checks should piles be constructed out of position;
6) embedment of raft
7) lateral load path analysis and load transfer into the raft slab.

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Shoring and earth retaining systems typically used and
accepted in Dubai are as follows:
a) non-watertight shoring systems:
1) soldier piles with lagging system/king post walls;
2) contiguous pile walls;
3) slurry walls;
b) watertight shoring systems:
1) secant pile walls;
2) diaphragm walls;
3) sheet piles;
c) bracing for temporary earth retaining systems:
1) anchors;
2) rakers;
3) struts.

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a) non-watertight shoring systems:
1) soldier piles with lagging system/king post walls;
2) contiguous pile walls;
3) slurry walls;
soldier piles with lagging system/king post walls
contiguous pile walls
slurry walls

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b) watertight shoring systems:
1) secant pile walls;
2) diaphragm walls;
3) sheet piles;
secant pile walls
diaphragm walls
sheet piles

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c) bracing for temporary earth retaining systems:
1) anchors;
2) rakers;
3) struts.
anchors
rakers;
struts

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Chapter 10 - Sessions 1 of geotechnical .pptx

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Chapter 10 - Sessions 1 of geotechnical .pptx