Orbital Highway and Truck Route (P023) Contract 4 J12A Geotechnical Interpretive Report

EXW-P023-0004-YD-DEC-RP-20100 Page 29 of 33

8 Geotechnical Recommendations

8.1 General Geologic Profile and Design Parameters

The general geologic profile at J12A location as well as the design parameters adopted for the

encountered rock layers, are given in the figure below.

Figure 5: General Geologic Profile and Design Parameters at J12A

8.2 Foundations design

A shallow foundation system is selected based on the encountered subsurface conditions, the

targeted foundation level and the anticipated structural loads. The adopted system should satisfy

two main criteria: bearing capacity and predicted settlements which shall be of an average around

2.5cm for isolated footings.

Given the findings of the drilled boreholes, the bottom of the foundations shall be placed at a

minimum depth of 3.0m below ground surface as to ensure removing the top highly fractured and

weathered rocks and placing the foundations on relatively sound rock.

In view of the high shear parameters of rock, it is expected that settlements will control the bearing

capacity of foundations. Therefore, settlement analysis is performed to ensure that the applied

pressure on the foundations relevant to service combination will keep the settlements within the

commonly recommended tolerable limits, i.e. an average of around 2.5cm. An average gross

allowable bearing capacity of 250 kPa is thus recommended as to meet the aforementioned

criterion.

TOPSOIL Average thickness = 0.5m

SIMSIMA LIMESTONE Average Thickness: 8m Cohesion: c = 162 kPa Friction Angle: = 21 Rock Mass Modulus: Em = 135 MPa

RUS FORMATION

Average Thickness: 12m Cohesion: c = 74 kPa Friction Angle: = 19 Rock Mass Modulus: Em = 55 MPa