Pablo Segarra

• PhD
• Professor (Associate) at Universidad Politécnica de Madrid

Identifying and predicting mineral grade is crucial in mining engineering as it directly influences the efficiency and profitability of extraction processes. By accurately determining ore quality, mining operations can optimize resource allocation, reduce waste, and make environmentally responsible decisions. Over the past few years, the image-base...

Blasting is a common activity in mining that can cause significant damage in the remaining rock mass. The most commonly used method for predicting vibrations is the Swedish or Holmberg-Persson approach. It is a simple and fast method that uses empirical formulation to estimate the vibration levels based on the explosive charge weight, distance to t...

Petroleum reservoirs are often influenced by various flow behaviours including the mixture of gas, water and oil. The gas relative permeability is used to estimate how much of the gas in the reservoir is producible at a given water saturation level. Therefore, the gas relative permeability is a significant parameter to characterize the behaviour of...

The utilization of recycled aggregates (RA) for concrete production has the potential to offer substantial environmental and economic advantages. However, RA concrete is plagued with considerable durability concerns, particularly carbonation. To advance the application of RA concrete, the establishment of a reliable model for predicting the carbona...

The full-field solution (FFS) of the seismic radiation from a blasthole is refined with the use of a source function consistent with the shock physics on the detonation shock/rock interface. This source function accounts for the directionality of the flow in the detonation front, that is curved under the influence of the confining rock, inducing on...

This paper describes a novel procedure to assess fragmentation from automatic analysis of 3D photogrammetric models with a commercial software. The muckpiles from 12 blasts were photographed with a conventional drone to build 3D photogrammetric models; the flights were made with a relatively constant ground sampling distance (GSD) of 6.2 sd 0.92 mm...

The utilization of recycled aggregates for concrete production has the potential to offer substantial environmental and economic advantages. However, recycled aggregate (RA) concrete is plagued with considerable durability concerns, particularly carbonation. To advance the application of RA concrete, the establishment of a reliable model for predic...

The modelling of discontinuities in rock mass is undertaken with different measurement techniques and used to determine the in situ block size distribution (IBSD). Two monitoring techniques are employed: televiewer logging of boreholes and photogrammetry of highwall faces in a quarry bench; televiewer performs at the borehole diameter scale, while...

A discrete fracture network (DFN) model based on non-parametric kernel density estimators (KDE) and directional-linear statistics is developed. The model provides a characterization of the fracture network with distributions of fracture orientation and size jointly. A solution to the Bertrand paradox is used for the calculation of disk sizes from t...

A procedure to recognize individual discontinuities in rock mass from measurement while drilling (MWD) technology is developed, using the binary pattern of structural rock characteristics obtained from in-hole images for calibration. Data from two underground operations with different drilling technology and different rock mass characteristics are...

In-hole detonation pressure measurements are unusual in the production environment of a mining operation, partly owing to the hostile conditions to which recording equipment and pertinent probes must be subjected and, partly by the constraints of the production cycle. In recent decades, detonation pressure measurement techniques have been developed...

This paper describes a mechanically operated probe integrated in an explosive charge-up unit. The probe is equipped with centralisers to minimize the measuring error. The system allows to place the probe inside blastholes drilled in any direction and to survey along its length by mechanically pushing the hose, while the operator stays in a safe pos...

The fragmentation of 12 full-scale one-row blasts has been measured by sieving a large portion of the muckpiles. The procedure followed, the difficulties encountered and the solutions adopted to construct the fragment size distribution curves are described in detail; 11 curves were finally constructed as production constraints prevented the require...

At present there is a lack of an instrument to measure the trajectory of up-holes in a safe and efficient way with minor disruption of underground production. To overcome this, a mechanically operated probe equipped with Inertial Measurement Units (IMU) and centralisers is integrated in an explosive charge-up unit, which allows the operator to star...

Blasting performance is influenced by mechanical and structural properties of the rock, on one side, and blast design parameters on the other. This paper describes a new methodology to assess rock mass quality from drill-monitoring data to guide blasting in open pit operations. Principal component analysis has been used to combine measurement while...

Mining represents the first step to the access to mineral resources. The impacts induced by such operations now contribute to the impacts of a wide range of goods and services, given the widespread use of these raw materials in the worldwide economy. In this context, this study aims at assessing the environmental performance of mining operations in...

This study analyses the frequency content of vibrations from blasting in the near field using a vibration prediction model called full-field solution (FFS). For that purpose, the frequency content of recorded signals and synthetic waveforms obtained through the FFS using dominant and mean frequencies have been compared and correlated with the geome...

A semi-analytical full-field solution for the radiation of seismic waves has been developed and applied to calculate the near-field vibration from blasting. The shape of the source function applied to the blasthole wall has been obtained from numerical modelling of detonation, with a peak value determined as the shock matching pressure of the deton...

Currently, the charging procedure for sublevel caving mining is carried out with no prior information of the rock mass condition. Thus, engineers are blindsided to unexpected rock conditions and ill-prepared to address issues associated with collapsing boreholes. This results on charging problems and, as consequence, bad fragmentation of the rock a...

A damage assessment methodology, based on the Schmidt hammer rebound value, has been developed and applied to evaluate the integrity of different structural elements after a blast event. All the elements (nine slabs, five beams and four masonry walls) were tested at full-scale with scaled distances that range from 0.2 to 2.92 m/kg1/3. The methodolo...

At present, modern jumbos equipped with MWD (Measure While Drilling) provide the position of the blastholes collar and, from the drill length and the azimuth and inclination angles (monitored outside the blasthole), the theoretical end position of the blasthole. Since the trajectory of the hole during the drill is not measured, deviations are not a...

The damage from blasting to the remaining rock mass is analyzed with the purpose of developing a drilling index from measure while drilling (MWD) parameters, able to predict high risk of potential over- and under-excavated zones produced by blasting in the contour of a tunnel. A new methodology based on the comparison of scanner profiles of the exc...

A microspheres-sensitized emulsion explosive, to be used in rock blasting tests, is characterized by means of the cylinder test. This test measures the expansion of a copper tube upon detonation of an explosive charge inside. Eight cylinder tests have been made with two different diameters (50 mm and 100 mm) and two different densities (1180 kg/m³...

Purpose The purpose of this paper is to investigate the applicability of the LS-DYNA software using a Lagrangian formulation in the jet formation, flight and penetration of improvised explosively formed projectiles (EFPs). Numerical results dealing with different properties of the EFPs have been validated with a significant number of field tests....

This paper investigates fragmentation in an aggregate quarry in the light of the fragmentation-energy fan concept. Six blasts were monitored, located one behind the other in the same quarry area. The rock structure was blocky, the water level and the usage of explosives were variable within and between the blasts; however, the distribution of explo...

The high cost and the difficulty of installing the drill monitoring system commonly known as MWD (Measurement While Drilling), especially in older drills, restrain the use of this technology in numerous small quarries and mines. An in-house MWD system is presented here as a low-cost alternative that allows monitoring the information of any rig whil...

A total of 43 tests were made on a vibration shaker to measure the transfer properties of a blasting seismograph. The main elements of the full monitoring chain are modelled using second order transfer functions. The parameters of these functions are calibrated through nonlinear fits of the measured responses. The form of the overall resulting tran...

Contour profile quality affects tunnel excavation costs, in terms of operational safety, support materials and construction time. In drill and blast tunnelling, under/over-excavation and rock mass damage arising from excavation phase can be evaluated by means of the elaboration of survey data and geophysical testing or coring, before and after the...

The mutual relation between Measurement While Drilling (MWD) parameters in percussive-rotary drilling is investigated in order to limit the number of MWD variables, and to select the more significant ones, that are required for a sound rock mass characterization. Cross-correlation of the MWD signals is used to determine their relations, the analysi...

Ten production blasts and one single-hole confined blast were monitored in two quarries in order to assess the measurable forms in which the energy delivered by the explosive is transformed in rock blasting. The seismic wave energy, the kinetic energy, and the fracture energy transferred in the blasting process were determined using the seismic fie...

In order to clarify the requirements for satisfactory coupling on rock, six methods to monitor vibrations with blasting seismographs are investigated in the longitudinal component of the vibratory motion. The methods studied consisted on placing the geophone mount on a granite surface freely (loosely), held with a sandbag, and attached with an anch...

The aim of this work is to assess the performance of different constructive solutions against explosions on the strength of masonry walls. The solutions tested, namely an external metal mesh, a glass fi bre fi lm on the external face of the wall and a basalt fi bre fi lm located on the inner face of the wall, have low to medium cost and are origina...

Field guidelines and recommendations for blasting vibration monitoring on a hard surface, suggest that the geophone mount should be coupled to the ground in a way that depends on the anticipated vibration level. However, the quantitative performance of the coupling method is basically unknown. In order to investigate this, the ground-to-mount coupl...

The Jones-Wilkins-Lee (JWL) equation of state parameters for ANFO and emulsion-type explosives have been obtained from cylinder test expansion measurements. The calculation method comprises a new radial expansion function, with a non-zero initial velocity at the onset of the expansion in order to comply with a positive Gurney energy at unit relativ...

The Jones-Wilkins-Lee (JWL) equation of state parameters for ANFO and emulsion-type explosives have been obtained from cylinder test expansion measurements. The calculation method comprises a new radial expansion function, with a non-zero initial velocity at the onset of the expansion in order to comply with a positive Gurney energy at unit relativ...

The capacity of 17 functions to represent the size distribution of fragmented rock is assessed on 1234 data sets of screened fragments from blasted and crushed rock of different origins, of sizes ranging from 0.002 to 2000 mm. The functions evaluated are Weibull, Grady, log-normal, log-logistic and Gilvarry, in their plain, re-scaled and bi-compone...

This thesis describes and analyzes the experimental work carried out in El Alto quarry (Morata de Tajuña, Madrid, Spain) within an E.U. funded research project “Less Fines Production in Aggregate and Industrial Mineral Industry” under the contract G1RD-CT-2000-00438. The “Less Fines” consortium includes research organizations: MU-Leoben (Austria),...

A Visual Basic application for Microsoft Excel 2010 has been developed and presented. The aim is to provide a tool through Moodle platform that helps professors to manage exams, works and tasks in courses with continuous assessment. Its application in a specific subject is also presented. Se presenta una aplicación desarrollada en Visual Basic par...

The capacity of 17 functions to represent the size distribution of fragmented rock is assessed on 1234 data sets of screened fragments from blasted and crushed rock of different origins, of sizes ranging from 0.002 to 2000 mm. The functions evaluated are Weibull, Grady, log-normal, log-logistic and Gilvarry, in their plain, re-scaled and bi-compone...

The uncertainties for four measuring conditions that are representative of common field monitoring techniques were studied. The data were obtained from 37 blasts carried out in Monte Espartinas gypsum quarry, Spain. The blastholes were charged with gelatine cartridges in the bottom and ANFO in the column. They were plugged with drilling cuts. Vibra...

Ten functions (Weibull, Swebrec, Gilvarry, Grady and Lognormal, and their bi-component versions) are fitted to 448 sets of screened fragment size data from blasted and crushed rock. The ordinary least squares criterion has been used for the fits and two minimization techniques have been tested, in both cases running the problem repeatedly with diff...

Twenty production blasts in two open pit mines were monitored, in rocks with medium to very high strength. Three different blasting agents (ANFO, watergel and emulsion blend) were used, with powder factors ranging between 0.88 and 1.45 kg/m3. Excavators were front loaders and rope shovels. Mechanical properties of the rock, blasting characteristics...

Full paper in https://lnkd.in/dWhec3n This paper investigates the advantages and accuracy of a finite element simulation of a blast loaded fullscale slab by validating the results with the corresponding field tests. For this modeling, a 3D pure Lagrangian approach using LS-DYNA with appropriate blast load routine (CONWEP), material models and suit...

This paper investigates the propagation of airblast or pressure waves in air produced by bench blasting (i.e. detonation of the explosive in a row of blastholes, breaking the burden of rock towards the free vertical face of the block). Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at whi...

A model for the calculation of the productivity of cyclic excavators is developed. The production rate results as a product of an ideal, maximum, productivity rate (one of the coefficients of the model) times an operating efficiency. The latter is described as a function of three variables (rock strength, nominal bucket capacity and explosive energ...

Size distributions of fragments of crushed rock in conveyor belts and of blasted rock in a muckpile obtained by sieving are compared with the size distributions obtained by digital image analysis of photographs of the same materials taken on-site. Several calculation methods are tested, based on the raw distribution of fragment areas and on the vol...

The ignition of firedamp by permissible explosives is assessed by means of gallery testing conducted by the Bruceton up-and-down method. Six test series were made in order to analyze the influence of several blasting practices in long-holes coal blasting, namely: use of slotted PVC pipes, detonating cord, salt cartridges and double (top and bottom)...

Ten production blasts and one single-hole confined blast have been monitored in two quarries in order to assess the measurable forms of energy in which the energy delivered by the explosive is transformed in rock blasting. The seismic field from seismographs readings, the initial velocity of the blasted rock face obtained from high-speed video came...

Der Beitrag behandelt die Bestimmung der Korngrößenverteilung von Sprenghauwerk in einem Steinbruchbetrieb auf der Basis der Analyse digitaler Bilder. Das zum Einsatz gebrachte Messsystem wurde an Hand aktueller Siebdaten kalibriert und über die Ermittlung eines Korrekturfaktors insbesondere für den Feinkornbereich mit der tatsächlichen Korngrößenv...

The operation of a digital image analysis system in a limestone quarry is described. The calibration of the system, required in order to obtain moderately reliable fragmentation values, is done from muckpile sieving data by tuning the image analysis software settings so that the fragmentation curve obtained matches as close as possible the sieving....