Evaluation of Tensile Strength-Strain Characteristics of Fiber-Reinforced Soil through Laboratory Tests

Tension cracking is a very important phenomenon in the case of compacted fine grained soils, which are commonly used in earth dams, embankments, and waste containment systems. The strength and permeability of earthen structures can be seriously affected by the formation of tensile cracks. The purpose of this paper is to evaluate the effect of discrete and randomly distributed fibers (DRDF) in improving the tensile strength-strain characteristics of bentonite amended natural silty soil. The authors conducted a series of direct tensile tests on unreinforced and fiber-reinforced soil by using a specially developed tensile test set up in the laboratory. They conducted tests by varying the fiber content and fiber length and studying their effect on tensile strength-strain characteristics and crack formation. The present paper indicates that the blending of fibers improved the tensile strength-strain characteristics and ductility of the soil. The authors carried out a digital image cross-correlation (DIC) analysis of images of top view of the soil captured during tensile tests to obtain the displacement vectors and strain field distribution. As the fiber content and fiber length increased while keeping other parameters constant, there was an increase in the strain at crack initiation and energy absorption capacity of fiber-reinforced soil and improvement in postcracking behavior. Further, they found longer fibers to be more effective in restraining cracks. The results of DIC analysis were found to be effective in reflecting the distinct strain field development at the onset of tensile loading with fiber inclusions of appropriate length and dosage.