96 publications from this institution
Abstract Tensile strength of brittle materials is usually obtained through Brazilian tests. It is accepted that failure is initiated at the centre of the sample and that it propagates through the material, creating a tensile failure plane along the vertical diameter or at the majority of it. Then, the tensile stress developed at the centre of the disc is considered as the tensile strength of the material tested. However, the stress state along the vertical diameter is always biaxial, even in the centre of the sample. This implies that the strength measured using such technique is not the uniaxial tensile strength. In this article, the expressions of the stress state supported by a tubular sample subjected to a novel device to determine the tensile strength of brittle materials are described. Besides, it is noticed that the failure plane contains points with the maximum uniaxial tensile strengths so the testing method is adequate to determine the uniaxial tensile strength of brittle materials.
International Society for Rock Mechanics and Rock Engineering, ISRM International Symposium 2020.- EUROCK (2020. Virtual conference)
El conocimiento de los parametros resistentes y deformacionales de un terreno constituye la base fundamental para estudiar cualquier tipo de actuacion que quiera proyectarse. Sin embargo esta caracterizacion en terrenos heterogeneos como escombreras, diques de tierra, rellenos antropicos o incluso algunos suelos de origen aluvial, constituye un problema que, a dia de hoy, aun no esta completamente resuelto. Esto es debido a que los ensayos convencionales, tanto “in situ” como en el laboratorio, presentan un problema de escala que impide caracterizar el terreno en su conjunto. Por otra parte, cuando es posible la realizacion de los ensayos su coste es demasiado elevado. Por estas circunstancias el numero de muestras representativas esta muy limitado para que pueda ser extrapolable con exito a todo el conjunto.En este trabajo se describe un equipo y procedimiento de ensayo de carga “in situ” denominado Hydraulic Cylinder Test (HCT) desarrollado por el Grupo de Investigacion de Ingenieria del Terreno de la Universidad de Oviedo. Este nuevo ensayo aporta sensibles mejoras en el estudio de terrenos heterogeneos. Ademas, entre sus ventajas destacan la sencillez de su puesta en practica, la rapidez de su ejecucion y su reducido coste.A lo largo de este trabajo se describe con detalle el equipo y sus componentes, asi como el procedimiento de ensayo propuesto. A continuacion se detalla su puesta en practica mediante la caracterizacion de un dique de contencion de una balsa de lodos, situado en el sur de Espana. Con el fin de determinar la fiabilidad de los resultados obtenidos en los ensayos realizados con este nuevo procedimiento, se comparan los resultados obtenidos con los datos procedentes de una campana de investigacion geotecnica llevada a cabo previamente. Por ultimo, se extraen las conclusiones obtenidas de la aplicacion del HCT.
Purpose This paper aims to present a computational approach which – setting off from measures obtained by using an overdrilling method – determines, automatically and accurately, stress changes undergone in terrain as a consequence of human activity. Design/methodology/approach The method presented uses the data from three boreholes and the elasticity theory to represent a numerical system whose resolution allows determining the stress state in a particular point. Since the system obtained is over‐dimensioned, the Levenberg‐Marquardt minimization method has been used in order to minimize errors. This paper details the analysis carried out in order to develop the computational method. Findings This paper provides the algorithm for determining inner stresses in a particular point of a rock mass. Besides, a method to verify obtained results is presented, including its computational encoding in C#. Furthermore, the developed methods have been integrated in a computer tool which presents the results in a graphic environment. Research limitations/implications The algorithms presented are applicable when using an overdrilling method to measure stresses. Practical implications A reliable determination of global stress state demands the use of any method that is numerically difficult to use. Thus, in practice, it is of great importance to dispose of some reliable automatic tool to calculate stress state. Originality/value Accuracy in the results obtained with the tool, together with the simplicity of its interface, involves a certain advantage regarding the use of a general‐scope commercial tool, since it allows – without being necessary to be an expert user – quickly obtaining results within the analysed working area.
