B. Deck slab or Amburson type buttress dams Here the deck structure is a reinforce concrete slab spanning across the buttress. This type is also called the Amburson type after the person who suggested it for the first time for a dam built at Theresa, N.Y. in 1903 but the design is adaptable to high dams as well. The layour problems involve fixation of suitable buttress spacing and the shape of the buttress head for providing support to the slabs.
The typical feature of this type of dam is its articulation or flexibility. It is desirable to allow for free expansion of slab in directions parallel to base line of the dam and along the slope. Longitudinal movement can be arranged by coating the slab support by bituminous mastic. The movement along haunch has to be restricted so that the stabilization effect of load is not lost. Hence keys are provided between the slab and the support.
The inclination of the deck is kept between 35 and 45 with the horizontal. Too steep slopes increase the tendency to sliding and too flat a slope cause a very high inclined stress at the heel.
Simple or Amburson deck slab buttress dam
In this type steel is placed at the downstream face, and hence there is no danger due to rusting. This type of dam is useful for wide valleys and the influence of temperatures, shrinkage and settlement of foundation is less marked. As the loads have to be transferred to the buttress through the corbels, objectionable stress concentration in corbels is likely to occur. Also, this type of dam requires thicker slab.