Quantitative measurement of the scour resistance of natural solid clays

Abstract

The erosion of clayey soils is a complex phenomenon that includes various types of erosive actions. A tentative classification of erosion processes is proposed. This paper concentrates on the scour resistance of solid clays. Available prediction methods are reviewed. Generally they propose relationships between physical or mechanical parameters and the critical hydraulic shear stress, [Formula: see text]c, that defines a boundary between "no erosion" and "erosion". It became apparent that the physicochemical parameters of both the clay and the eroding water control the erosion process. However, subsequent studies on these parameters have yet to yield reliable predictions of natural clay erodibility from indirect measurements. An erosion testing program was therefore performed on three Quebec clays with the improved rotating cylinder technique. In this test, intact or remolded samples can be tested, physicochemical parameters can be controlled, and the hydraulic shear stress [Formula: see text] and the erosion rate ė can be adequately determined. A relatively complete and accurate graph of ė versus [Formula: see text], including ė values for [Formula: see text] values lower than critical can be established. Previous and present research underline the need to exert a strict control of all clay and water parameters, including that of sample preparation, in order to adequately simulate a field problem. Key words: erosion, clay, scour resistance, physicochemical properties, rotating cylinder test.