ABSTRACT
Cohesive soils are reported to have the highest cutterhead clogging potential in the consistency index (Ic) range of 0.50–0.75. The stickiness index (λ) determined from laboratory mixing tests on a soil sample has been used as an indicator of clogging potential. However, the values of λ that define the range of a clogging potential category are yet to be validated using the data from mixing tests conducted on a wide variety of soil types from different projects whose cutterhead clogging behavior is documented. In the present study, mixing tests were performed on six different clayey soils covering the Ic range between 0 to 1 to study the influence of soil type and specimen volume on the variation of λ with Ic. From the test results, it is observed that magnitude of λmax (maximum stickiness index) varies for different soil types, whereas the critical Ic corresponding to λmax (Icct) falls within a unique range (0.8–1.0) for all the soil types tested. The results from mixing tests conducted in the study are compared with the data from the literature that corroborated with the findings of the present study. The dependency of λmax on soil type suggests that the clogging potential criterion solely based on λ value may not provide a complete picture of soil’s clogging potential. A two-fold criteria in which soil in its critical Ic range is tested for λ, and the clogging potential is then determined by comparing the laboratory λ with the values of λ obtained from tests on in-situ soils whose clogging potential behavior is known, provides a promising approach to determine soil’s clogging potential from laboratory tests.
