Rockfill modulus and settlement of concrete face rockfill dams

A method is presented for estimating the modulus of compacted rockfill in dams based on the particle size, unconfined compressive strength of the rock, compaction layer thickness, compactive effort, and the applied vertical stress. Also presented are methods for predicting the crest settlement and face slab deformation of concrete face rockfill dams during first filling and in the long term. It is demonstrated that the modulus is stress dependent and guidance is provided on how to assess this, as well as effects of construction in narrow valleys where arching may affect the stresses in the dam. These methods are based on analysis of the 35 dams with good quality information on construction materials and placement methods, and good quality internal and surface settlement monitoring records.