Numerical modeling of pull-off test in basaltic rock considering the fractures Iniciation and propagation by means of XFEM

Abstract

The tensile strength of rocks is an important property in the stability of underground openings, slopes, etc. There are some traditional test methods, such as the Direct Tensile Strenght (DTS) and the Brazilian Tensile Strenght (BTS), and others, alternatives, that allow its determination, but these have some limitations. The Pull-off test (POT) is a test method of tensile strength currently used in concrete and coatings, which allows simple execution in the field and laboratory. In view of this, it is being tested at the Polytechnic School of the University of São Paulo, by the research group GeoInfraUSP, for its possible use in rocks. This research aims to study the mechanical behavior of basalt rocks tested by POT in order to understand and explain the physical phenomena involved in the test. The study will be carried out through numerical simulation, by the eXtended Finite Element Method (XFEM). This method will simulate the initiation and propagation of rock fractures, which will provide a more realistic analysis of the problem. The numerical model of the POT will be calibrated with laboratory test POT, will be compared with numerical models of DTS and BTS and with the literature. Finally, a parametric study of geometric and mechanical properties will be carried out. This research will contribute to the proposed use of this test method in rocks.