Stress-Dilatancy Performance of Feldspar

The recently developed stress-dilatancy theory is a major advance in the field of stress-strain relationships of soils. Experimental evidence showing the conditions under which the minimum energy criterion postulated in the theory is obeyed, has been published for cohesionless soils with interparticle friction angles (∖a/_μ) varying between 7○ and 26○. Because of the accuracy necessary to investigate the validity of the theory, an attempt was made to establish uniform strain conditions in the sample by the use of frictionless ends. The errors involved in strain and volume measurement were analyzed and techniques were modified to eliminate such errors as far as practicable. Samples were 4 in. in diameter and 4 in. long. The range of lateral pressure was 10 psi to 95 psi. Both normally consolidated and overconsolidated samples were tested. The maximum overconsolidation pressure was 120 psi. On the basis of the stress-dilatancy theory Horne has developed a relationship between ∖a/_μ and ∖a/_cv. The present tests provide data for a critical test on the validity of the predicted ∖a/_cv values.