Ground condition in Jeddah and its influence on selection and design of foundation

Abstract EN

A general assessment is made of the sub-soil and groundwater conditions in the 12 km long central part of Jeddah and of their influence on the selection and design of foundations.

This is based on a review of 44 site investigation reports, testing of soil samples from 55 locations and water samples from 12 locations and design calculations made by the authors.

The soil and rock units identified within a maximum depth of 60 m arc: (i) light brown silty gravelly sand, (ii) white loose uniformly graded sand, (iii) greyish brown loose to dense clayey silty sand, (iv) white loose to dense coralline silty sand, (v) fill material, (vi) white coralline conglomerate (roek) and (vii) light brown massive coralline limestone (rock).

The studied area has been divided into four main zones nearly parallel to the coast and with soil units (i), (ii).

(iii) and (v) at the surface.

In Zone I, footings are found to be adequate for buildings upto 6 stories high and rafts for taller buildings.

In the other zones, deep foundations arc more often necessary and bored piles are more commonly used.

Protective measures against sulphate attack on foundation concrete and against corrosion of steel by chloride is found necessary.