The effect of cyclic loads on the surface profiles of ECC linings cast on foundations comprising crushed stone and compacted soil was investigated. A geotextile was embedded between the crushed stone and ECC lining for some of the samples. After 28 days of water curing, the hardened surfaces were loaded and monitored for roughness and crack development by measuring surface levels and crack widths, respectively. Neither cracking nor significant variations in the lateral profiles were observed on all the samples for all the loads applied. However, significant variations which depended on the foundation types were observed in the vertical profiles. It was concluded that while ECC can resist cracking due to its high strain capacity, its flexibility causes ECC linings to assume the shape of the foundation material, which can increase the surface roughness at certain loading configurations. 1. Introduction An open channel is medium in which a liquid flows with a “free surface,” which is defined as the interface between the moving liquid and an overlying fluid at a constant pressure [1] with water and air being the most common liquid and fluid, respectively. Both natural open channels such as rivers, streams, and rivulets or artificial ones such as irrigation canals and storm-water drains tend to have a wide variability in magnitude, shape, and roughness. However, since a free surface exists in the liquids flowing in all these channels, their flows are governed by the same laws of fluid mechanics [2]. Essentially, all open channels have a bottom slope, and the prime motivating force for liquid flow is gravity. As such, the mechanism of the flow can be simulated to the movement of a mass body down a slope due to gravity. Basically, the component of the weight of the liquid along the slope acts as the driving force, while the boundary resistance at the perimeter of the channel acts a resisting force [3]. On the other hand, the component of the liquid perpendicular to the slope of the channel exerts a downward load on the surface of the channel, which is usually lined to enhance the stability and vitality the channel. Moreover, a subsurface drain may be inserted in the foundation of the open channel to separate groundwater from surface water and avoid the buildup of water pressure which can damage the channel lining [4]. Types of subsurface drains include porous concrete, crushed stone, and river gravel [5]. In line with Newton’s laws of motion [6], interactive loads are expected at the lining/subsurface drain interface. Essentially, it is desired that after the
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