Correlation of Shallow Depth Sediments Along Shahreza Avenue – Teheran

Soil investigation and correlation of the shallow sediments along Shahreza Avenue was required for a traffic overpass project. The stretch under the investigation
in shown in shown fig. 1. The footings of the overpass were designed to be spread on the center of the heavily trafficed avenue. The approximate estimation of the lead required on each footing showed that an investigation of the deposits down to about 25 meters depth from the ground surface was necessary.
The area under the investigation was claimed to have been a moat in the ancient time. It was therefore necessary to find out the depth of the filling material as well as correlate the deposits.
For this purpose, electrical, magnetic or seismic subsurface exploration was
not possible since shocks due to the heavy traffic, concuctivity, of underground
water pipe and electric cables would not permit a correct interpreatation of such
exploratory means. Drilling too many boreholes was also impossible due to the
presence of heaffic even at midnight. Two borings to a depth of about 20 meters
at the two end of the strech were the only alternative therefore. The samples from
these two boreholes which were about 120 meters apart had to be so carefully and
meticulously studied so that the continuity of the deposits along the avenue and
its nature (filled material or natural deposits) could be ascertained.
The chemical prperties (Organic content, so3%, loss on heating.... ) ; the
gradation analysis, standard penetaration test results, density, natural moisture
content, flakiness and elongation percent of the samples were therefore determined
and correlated.
Finally, the depth of pervious moat was estimated, the continuity of the
deep layers confirmed, the character of the subsoil explained in detail and the bearing
capacity for the footings to be constructed on the layers was established.