Επίδραση του τρόπου φόρτισης στην τριαξονική συσκευή

Abstract

The purpose of this diploma thesis is to study the effect of loading mode on the undrained response of sands in the triaxial apparatus by carrying out experiments on specimens of four sands. Other factors affecting the results of triaxial tests are also investigated, such as the effect of lateral stress, the effect of porosity and the effect of the shape of grains. The experiments were carried out in Triaxial Stress Path Cells of the Soil Mechanics Laboratory at NTUA. Nineteen experiments were carried out in total on four different sands (M31, Fontainebleau, Ham River Sand, Longstone). The samples were consolidated at three different effective stress levels (100, 200 and 300kPa), in a loose and dense state and were subjected to shear loading by two different methods of imposing load: strain control and load control. This diploma thesis consists of two parts. The first two chapters of Part A’, mainly refer to the description of the mechanical behavior of non-cohesive soils (mainly sands). The third chapter is devoted to describing and understanding the operation of the triaxial apparatus and the fourth chapter contains important geotechnical publications in the literature on factors affecting the results of triaxial tests. Part B’, deals entirely with the results of the experiments conducted in the laboratory. The characteristics of the used sands, the description of the experimental procedure, as well as the presentation and analysis of results and comparative charts are included herein. Finally, Part B’ contains the conclusions of the thesis, according to which, although the loading mode does not seem to affect the general form of the response of sands (stable or unstable behavior), for the sands with the unstable response, the tests which were conducted under strain control mode show less tendency to contact than those which were conducted under load control mode.