Page 14 - Building Regulation and Design Guidelines - Structural (Grey Code)

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

1.2.32 Cyclic stress ratio (CSR) induced in the soil due to earthquake shall be
estimated considering Richter Magnitude M=6.0, (Amplification Factor =
Well
1.5) and ground motion parameters as follows:
Ground Surfaces
• UBC zone class: 2A, ground acceleration a=0.225g at ground level
or 0.15g at cap rock level.
• UBC zone class: 2B, ground acceleration a=0.275g at ground level
Direct Wave or 0.2g at cap rock level.

Lower Reciver 1.2.33 Calculation of cyclic resistance ratio (CRR, soil “strength”) based on
in-situ test data from SPT (Seed & Idriss) or CPT method (1996 NCEER
workshop on Liquefaction Evaluation).
2m
Downhole Hydrone
Upper Reciver 1.2.34 Evaluation of liquefaction potential by calculating the factor of safety
against liquefaction from the earthquake load and soil strength.
1.2.35 [F.S. = CRR/ (1.2-1.5) CSR]. There are a potential for liquefaction if the
F.S. less than unity, the layer is susceptible to liquefy and the ground
densification or mitigation measures are needed.
Fig. (1.7). Standard Down Hole Seismic
1.2.36 Estimation of liquefaction induced settlement.
Soil/Rock Shear Wave SPT UCT Range Soil
Description Velocity (m/s) Range (Kpa) Pro le Type
Hard Rock 1500 - - S A 1.3 RECOMMENDATIONS TO BE INCLUDED IN THE SOIL INVESTIGATION
Rock 760 to 1500 - - S B REPORT:
Very Dense S
Soil & Soft Rock 360 to 760 > 50 100 C 1.3.1 EXCAVATION WORKS: Excavation works should be carried out in
180 to 360 15 to 50 50 to 100 S D accordance with good construction practice and following BS 6031:2009
180 <15 50 S E “Code of Practice for Earthworks”. Recommendations for excavation of
S F
SPT: Standard Penetration Test on Soil rock for cases of deep excavations should be provided. Fig. (1.8).
21 22 23 q=100kps
31
50 30
20 33
c 19 90 3
In addition, the following other parameters can be considered: 16 1718 18 Roack Armour Cole Maloe 5040 34 35 36 38 37
7 8 9 10 11 14 15 27 52 5354 55 50 57 40
and C can be considered with depending on the 12 13 44 48 25 18 47 48 5050 51 72 55 74 4
26 48
Seismic v a 52 70 64 64 66 87
Zone Factor (Z): 82 81
Swismic Zone Factor Z=0.15
S A S B S C S D S E 7 Bedrock
0.12 0.15 0.18 0.22 0.30 40 50 60 70 80 90 100 110
C a
0.12 0.15 0.25 0.32 0.50 Fig. (1.8): Safe angle for open excavation
C v
D a is 0.22 1.3.2 OPEN EXCAVATION AND PROTECTION: Where space permits and above
D is 0.32
the water table, sides of the excavation would be necessary to be battered.
Table (1.9): UBC 1997 Soil Profile Class Estimation The CIRIA Report No. 97 “Trenching Practice” recommends a maximum
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