Publications

Nuevo ensayo de caracterización de la resistencia a tracción de materiales rocosos

Muchos de los fallos que ocurren en materiales empleados en Ingenieria (como hormigon y acero), estan gobernados por la resistencia a traccion. Sin embargo, esto difiere en macizos rocosos, donde los mecanismos de rotura mas frecuentes responden a campos de tensiones que predominantemente actuan en la region compresiva. Este aspecto, anadido a la baja resistencia a traccion de las rocas, ha priorizado el estudio del comportamiento rocoso en el dominio compresivo frente al de traccion. Para calcular la resistencia a traccion en rocas, destacan fundamentalmente metodos de determinacion indirectos, debido a la dificultad de reproducir condiciones de traccion uniaxial en laboratorio. Dentro de estos metodos el mas utilizado es el ensayo Brasileno, aunque existe un gran debate en la conveniencia de emplear este metodo de ensayo ya que el valor de resistencia a traccion obtenido con el difiere del calculado con metodos directos. En este sentido, muchas investigaciones afirman que subestima el verdadero valor de resistencia a traccion, lo que se traduciria en que el ensayo Brasileno es conservador puesto que, al minimizar la resistencia a traccion, opera en el lado de la seguridad. Esto es favorable desde el punto de vista, por ejemplo, de un sostenimiento en una obra civil. Sin embargo, si se pretende aprovechar la debilidad presente en diferentes rocas con vistas a su explotacion como es el caso de las rocas ornamentales, se requiere un conocimiento preciso de los parametros que controlan la rotura para optimizar el proceso.En este trabajo se describe un dispositivo y procedimiento de ensayo de caracterizacion denominado “Ensayo de traccion mediante cuna” desarrollado por el Grupo de Ingenieria del Terreno de la Universidad de Oviedo. El dispositivo, de sencilla aplicacion, ha demostrado estar mas proximo a la verdadera resistencia a traccion utilizando un material de resistencia a traccion uniaxial conocida. La fiabilidad del metodo ha sido comprobada en material rocoso, mediante su comparacion con datos procedentes de estudios previos.

Comparison of limit-equilibrium, numerical and physical models of wall slope stability

Forensic analysis of a pile foundation failure

New insights into the relevance of the length-to-diameter ratio on the compressive behaviour of rock specimens

Abstract The precise determination of uniaxial compressive strength (UCS) is crucial for assessing the load-bearing capacity of geological materials. To ensure the reliability and reproducibility of results, various standards and recommendations have been established. Although indirect measurement techniques exist, the uniaxial compression test (UCT) remains the benchmark for precise UCS characterization. However, discrepancies between the theoretical assumptions underlying the test and the observed outcomes—such as variations in the accepted failure patterns and sensitivity to specimen and platen properties—highlight the need for deeper analysis. In this context, numerous standards recognize the major influence of the specimen’s length-to-diameter ratio ( $$\:L/D$$ ), yet they recommend different $$\:L/D$$ values. To elucidate its relevance in the stress field generated within the specimen, this study investigates the stress distribution within cylindrical rock specimens across a range of L/D ratios (0.1, 1.0, 3.0, and 5.0), using a validated modelling framework supported by previously obtained experimental results. Findings reveal that the use of standardized steel platens slightly alters the stress ratio at the failure initiation point, deviating the stress state from the desired uniaxial compression condition. To address this, a method for identifying an optimal L/D ratio is proposed, enabling failure to initiate under conditions that closely approximate true uniaxial compression. Additionally, it is demonstrated that the deviations produced by the standardized platens can be mitigated by employing platens with stiffness comparable to that of the tested specimen.

Changes on diametral compression behaviour of compacted marls due to drying

Cracking due to desiccation can compromise the behaviour of earth structures built with compacted clayey soils by promoting water access and consequent volume changes on further wetting. Tensile strength therefore is important to be considered when studying the behaviour of such structures, and in particular its dependence on the degree of saturation or water content. The influence of water content in tensile behaviour of compacted marls was investigated by performing diametral compression tests (Brazilian splitting tests), where axial deformations were measured besides strength. The samples were prepared by compaction at optimum point using standard compaction energy (optimum water content 16%) and then dried by vapour equilibrium to reach water contents between 5% and 16%. The correspondence between water content and suction was done by using the drying branch of the water retention curve, measured using WP4 equipment (Water Dewpoint Potentiometer). Good relationships were found between tensile strength and the water content (and suction). In addition, the study was completed with the analysis of other parameters such as the semi-contact angle created in the loaded area and the stiffness of the material, which also showed changes with water content.

Stability analysis of Llerin Rockfill Dam: An in situ direct shear test

Predicting blasting propagation velocity and vibration frequency using artificial neural networks

The design and results of an innovative instrumentation method for monitoring and improving the excavation of a road tunnel in a highly fractured and strained rock mass

A new procedure for in situ determination of the Poisson ratio of a rock mass

Urban development and human activity as factors in terrain instability in Tijuana

Application of genetic algorithms in the optimisation of steel rib supports

Numerical modelling and analysis of the influence of local variation in the thickness of a coal seam on surrounding stresses: Application to a practical case

A New SJ* Value Based on Sievers’ J-Miniature Drill Tests to Determine the Drillability of Limestones

This research presents a new drillability value (SJ*) that corrects the most-used Sievers’ J-value (SJ) by removing the accommodation effect of the drill bit in the first tenths of a millimetre to better represent the real drillability of limestones. Moreover, this research demonstrates how such an effect is more notable when porosity and micro-cracking increase, which in this study has been achieved by inducing thermal damage in the samples. To do so, limestone samples from the Prada formation were subjected to temperatures of 105, 300 and 600 °C and then cooled at fast and slow rates to induce porosity and micro-cracking. Two characteristic zones were identified in the penetration–time plots: (a) a shallow region (Zone 1) with a variable drilling rate including an initial peak and (b) a deeper region (Zone 2) where the drilling rate stabilises. These drilling rates increase with thermally induced porosity and micro-cracking, and the authors propose a new method to delimit Zones 1 and 2. Zone 1 is attributed to the time it takes for the drill bit to adjust and settle in the rock surface, while Zone 2 more realistically represents the drillability of the material. The above influences the SJ value derived from Sievers’ J-miniature drill tests, so a new drillability value SJ* is proposed that corrects SJ by excluding Zone 1 and giving more weight to Zone 2. The novel SJ* presented in this research constitutes a more accurate tool to assess and predict the drilling performance in limestones.

Back analysis and radar interferometry monitoring in a large open pit slope

Determination of the stress state in a rock mass subjected to excavation

Rock Mass Characterization for CAES System Applications and Analysis of the Behaviour with Cyclic Loads

Trabajo Fin de Grado : una visión crítica

Predicción y control de subsidencia por excavaciones subterráneas

Este trabajo plantea, fundamentalmente, dos objetivos: evitar la subsidencia minera y, cuando no se posible, predecir los danos que pueda ocasionar sobre las actividades humanas. En este trabajo se analizan y discuten, en primer lugar, los criterios de rotura para macizos rocosos, realizando una serie de aportaciones a los mismos. Posteriormente se propone una metodologia de diseno de pilares para la mineria de camaras y pilares, validada en casos reales. Una vez finalizadas las circunstancias en que puede tener lugar la subsidencia, se propone un modelo fisico que describe el comportamiento del terreno y se implementa una formulacion matematica que caracteriza, desde el punto de vista espacial, dicha subsidencia, basada en el metodo de las funciones de influencia. La funcion propuesta es general, aplicable a capas de cualquier potencia, profundidad e inclinacion. Se comprueba que con ella puede obtenerse gran numero de la cubeta de subsidencia. Posteriormente se formula una nueva funcion que permita evaluar la evolucion de la subsidencia con el tiempo, denominado funcion de influencia temporal tipo normal. Se ha desarrollado tambien un programa informatico, denominado SUBSIDENCIA-3D, que incluye ambas funciones de influencia. Por ultimo, se analizan varios casos reales de la cuenca carbonifera asturiana.