Selection of core material for an earth dam in the lower Çekerek basin, Tokat, Turkey

Abstract

This study aims at determining the suitability of the impervious to semi-pervious soils in Çekerek basin (Tokat, Turkey), as core and filter materials in an earth dam. Laboratory experiments were carried out on 20 samples from the study area for determination of geotechnical properties. Then the materials were evaluated according to their maximum dry unit weight (gdmax), optimum water content (wopt), specific gravity (Gs), liquid limit (LL or wL) and plasticity index (PI or Ip). All the parameters (except, of course specific gravity) indicated the undesirable characteristic as an impervious fill material. Especially the high value of optimum water content was judged as restricting the usefulness. Relative desirability rating for core and homogenous fill was determined to be 9 (very low level of desirability) for CH group clays in the colluvium. Although the clay materials from the colluvium would be impervious after compaction, it is thought that problems would be occurred when they used as core or homogeny fill material in an earth dam. According to the results of index, water suction, quantity of clay ball, strength loss after frost and Los Angeles abrasion tests on the samples from alluvium, these materials were evaluated as desirable as pervious/semi-pervious material, although the strength loss after frost have the value greater than the proposed ranges. So, due to the warm climate conditions of the study area, this deviation would not be a problem when they were used in the filter zone of an earth dam. This material can also be used in upstream and downstream fill covering the core of an earth dam, due to their gravel contents, because of SP group material desirability rating of 4. © 2004 ejge.