Shear strength behavior of granular fill-clayey soil interfaces and improvement with dowels

Öztürk, Şevki
Shear failures of interfaces between granular material and clay are frequently encountered in engineering practice. In earthfill dams, road embankments and spoil piles in mining operations, granular materials are placed on clay, and shear failures and/or large movements are observed along interfaces. When dealing with this type of a problem selecting representative shear strength parameters is difficult. Furthermore in the literature no accepted procedure is available to select these parameters. This study aims to assess the shear strength behavior of interfaces between granular materials and clay soils. For this purpose, drained direct shear (small and large scale) tests and triaxial tests have been conducted on samples composed of clay, granular soil and granular soil-clay interfaces. All of the experiments were continued up to large displacements to determine large strain behavior. The results of all experiments are presented in the thesis, and comparisons have been made among all test results, the main focus being directed to select shear strength parameters for the interfaces. Sand-clay and gravel-clay interfaces yielded several degrees of additional friction angle compared to drained friction angle of clay at large strains. The effect of dowels that reinforce the gravel-clay interface is also studied through model experiments in large shear box. Depending on the length and number of the dowels, shear strength increased considerably especially in case of longer dowels, and it proved to be an effective way to increase the shear strength of granular soil-clay interfaces.
Citation Formats
Ş. Öztürk, “Shear strength behavior of granular fill-clayey soil interfaces and improvement with dowels,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.