A Modified Suction-Controlled Direct Shear Device for Testing Unsaturated Soil and Steel Plate Interface

The interfaces between saturated/unsaturated and structure are common to many offshore and on-shore civil engineering structures, but their behavior is not well understood. The shearing behavior of the interface plays a significant role in the stability and serviceability of the associated structures. With this in view, to study the influence of matric suction on interface (a stainless steel plate), a suction-controlled direct shear apparatus was modified. The main modifications included the fabrication of the shear box base/test cell for interface testing, along with some other important features and modifications that are described in this paper. By utilizing the modified direct shear apparatus, several suction-controlled direct shear tests were conducted on both the soil and the soil-steel plate interface. The main aim of this study was to develop laboratory testing equipment that can be used to determine shear strength of unsaturated soil-steel interfaces, at different shearing planes. The typical test results obtained from the study are presented and discussed in this paper, and it has been observed that the modified apparatus is suitable for testing the unsaturated soil-steel plate interfaces.