For construction of bridges in water courses, vertical or nearly vertical driven piles are usually used as the foundation element, because they could be constructed in the presence of water which means quick and cheap construction. Recently, many problems have arisen in several bridge sites using driven piles in water courses. Three such sites have been investigated by the author. A full assessment of those sites was required to avoid the risk of failure. In this paper, the assessment of a case study at the first site is presented and discussed. A comprehensive geotechnical investigation was carried out. Examining the results of the field and laboratory tests showed the presence of a soil layer at the design pile toe level which is very dense and explains the refusal happening while driving the piles. The field investigation also showed that a platform of steel beams and wooden logs built on wooden piles was used for the pile driving machine in the presence of water. The presence of the platform lead to the contraction of the water course cross section and the contraction gets worse by driving the reinforced concrete piles which in turn lead to a higher water velocity causing scour around the driven piles. Therefore, the stability of the piles became questionable, because of the shorter embedment length due to the refusal of the piles and the scour around them. The stability of the piles under the new conditions in the field was investigated using three criteria; the pile capacity, the buckling length, and the bending moment on the piles. It was shown that pile refusal and the scour reduced the allowable pile capacity. It was also shown that the slender ratio of the piles in 3 supports exceeded the limit defined in the Egyptian code and is unsafe in buckling.

This paper studies the effect of wave loads on the submerged piles. The submerged piles are used widely in harbors, and offshore structures.The bottom part of the pile is buried in soil under the mud line while the upper part (free height of the pile above the mud line) is subjected to waves. The internal forces induced in the pile depend on many factors such as, pile diameter, soil type, water depth, wave period and height. A numerical model for a submerged pile was developed using a commercial Finite Element program to study the internal forces induced on submerged piles which subjected to wave action. The factors affecting the internal forces induced in the pile, due to the wave load, were studied. In the present research, range of different values for each factor was taken into consideration to establish the effect of each factor on the internal forces induced in the pile. The results were summarized in curves to highlight the effect of each factor.