The influence of membranes on tests of coarse-grained materials at low cell pressures

摘要: In triaxial tests on small specimens of sands/silts and clays, cell pressures are usually greater than 100 kPa membranes relatively thin (~0.3 mm). such the influence membrane stresses specimen is ignored. Where and/or strength low increases. circumstances corrections may be applied assuming right cylinder deformation wall or circular hoop behaviour. However, there in which these methods correction invalid. For example when material tested has a large particle size relative to diameter (e.g. D100 approaches 1/6 diameter) behave neither as walls nor hoops. Tests railway ballast fall into this category; par-ticles require larger thicker membranes. The thickness more significant proportion have specimen. Fur-thermore, often carried out at replicate field conditions where influ-ence greater. investigated by means discrete element method simulations using spherical particles face centred cubic packing. modelled an array points surrounding connected elastically. Using closed form solution for packing used, initial quantified differing properties. Furthermore, first step developing way correct grain sized physical specimens, parameters identified that correlate influences