Stability of terrafix blocks under wave attack

Abstract

This study was undertaken to provide Terrafix Erosion Control Products Inc. with experimental data on the stability of their block systems when subjected to wave attack. The Terrafix block system is one of many different schemes developed over the years to protect revetments from wave attack. Systems as varied as rip rap, asphalt, tires, interlocking blocks and large armour units such as dolos and tetrapods have been employed. See, for example, McCartney, 1976. Each system has unique characteristics and must be tested either in prototype or model to determine what sorts of conditions it can withstand. For example, rip rap systems gain their stability primarily due to the weight of the 'individual stones, whereas armour units like the dolos gain extra stability by their interlocking capability. The Terrafix systems are made up of various types of interlocking blocks overlaying filter cloths and subgrade. These systems get a portion of their stability from their interlocking feature. Some interlocking block systems have undergone testing (see 'Literature Cited' section in McCartney, 1976), and in fact one style of Terrafix blocks has been tested (Führböter, 1975). However, each block type has different geometry, tenon and mortise structure, and mass so that it is necessary to conduct tests on each to define its stabili ty.