Direct shear in conditions of constrained dilatancy
This chapter highlights research conducted with the use of dilatometric apparatus of direct shear (DADS) and modernized standard shear apparatus BCB-25 employing the constrained shear method. The experiments were aimed at establishing the peculiarities of ‘soil-against-soil’ shear, comparing the obtained results with the contact shear data, and matching experimental performances of the Dilatant Apparatus of Contact Shear (DACS), DADS and BCB-25 instruments. During DADS instrument testing, the authors attempted to model shear conditions both for equamodular soil medium, and for the contact of layers with different values of modulus of elasticity. The tests in the DADS and BCB-25 instruments conducted by the constrained dilatancy method corroborated the data obtained in the course of DACS experiments. The obtained results were substantially influenced by the clearance between rings of the box of the movable and immovable carriages, the slant of pistons and the possible loosening of the sample occurring in the process of its placement into the instrument.