Evaluating CPT and CPTu based pile bearing capacity estimation methods using Urmiyeh Lake Causeway piling records

Abstract

Urmiyeh Lake is the largest super salt water situated in the north-west of Iran. A causeway embankment has been constructed in the narrowest part of the lake from both sides about 13.5 km, in order to connect two provincial capital cities of Tabriz and Urmiyeh of eastern and western Azerbaijan provinces to Europe through Turkey, while a 1280 m opening in between linked up by a bridge. Based on soil classification methods, utilizing CPTu data and soil sampling, the lake sediments consist of 150 m of soft and very sensitive clay. In order to evaluate the bearing capacity of driven piles of the bridge, eight long steel piles with diameters of 813 and 66 m and lengths of 75 m have been instrumented and monitored based on static and dynamic load testing program. Piezocone (CPTu) results are also available from adjacent pile locations. Results of pile capacity calculation based on direct CPT and CPTu methods demonstrate that reasonable accuracy can be achieved in reference to dynamic testing. Therefore, combination of CPTu data with dynamic testing results can be considered by engineers for predicting bearing capacity of piles in offshore and bridge structures, where the static pile load testing is difficult, time consuming and expensive in marine environment.