Experimental Study of Cantilever Failure in the Upper Part of Cohesive Riverbanks

摘要

With regard to many ambiguities existed on different types of cantilever failure in composite riverbanks and field study problems of this type of bank erosion, this phenomenon is not widely considered by other researches. The aim of this research was to investigate the experimental study of cantilever failure using data obtained from a field study in eroded banks of Kordan River. For this purpose, we used two samples of susceptible soil which were eligible to form overhanging block in riverbanks, in physical model tests. The physical, chemical and mechanical characteristics of those samples were previously determined via various tests. Accordingly, a soil block with optimum moisture contents and different densities has artificially been formed and consequently, certain depths of block are undermined in certain time steps. Then, the stability of overhanging block was assessed in each step. Finally, the failure pattern and related mechanism of cantilever failure was provided based on continuous images taken from deformations of soil block. Experimental results show that at least for our laboratory study conditions, the dominant failure mechanism is a toppling and this finding is in accordance with overhanging failure pattern, observed in Kordan Riverbanks. Also, failure mechanism in Cohesive Soil (CL) was progressive and accompanied with tension crack development. But in Loess Material (ML), the failure mechanism was momentary and deformations in upper part of soil block were not observed.