Laboratory test types
Laboratory tests are the basic tools for the study of stress-strain strength properties of soils. This chapter focuses on additional types of tests such as the triaxial and the direct shear ones. The following aspects are analysed: stress paths, drainage conditions, equipment and advantages and disadvantages of each type. The chapter discusses common laboratory test conditions in: isotropic compression; oedometer compression; triaxial compression. It explains that stresses and deformations in laboratory tests are direct shear; simple shear; ring shear. Drainage should be allowed throughout the test, since there is no way of sealing the specimen. In fact, even if porous stones were replaced by steel plates, it would not be possible to control drainage in the direct shear. Drainage control is performed by means of a valve that is the only possible path for incoming or outgoing water.