Tiago F. S. Miranda

New Models for Strength and Deformability Parameter Calculation in Rock Masses Using Data-Mining Techniques

Due to the inherent geological complexity and characterization difficulties in rock formations, the evaluation of geomechanical parameters is very complex, mostly in the initial project stages and in small-scale geotechnical works, where information is scarce for the definition of an accurate geotechnical model. However, in large geotechnical projects, a great amount of data are produced and used to establish near-homogeneous geotechnical zones. If properly analyzed, these data can provide valuable information that can be used in situations where knowledge of the rock mass is limited. Yet, this implies the organization of geotechnical data in formats for proper analysis using advanced tools which is not normally done. Data-mining techniques have been successfully used in many fields but scarcely in geotechnics. They seem to be adequate as an advanced technique for analyzing large and complex databases that can be built with geotechnical information within the framework of an overall process of knowledge d...

Estimation of the Rock Deformation Modulus and RMR Based on Data Mining Techniques

In this work Data Mining tools are used to develop new and innovative models for the estimation of the rock deformation modulus and the Rock Mass Rating (RMR). A database published by Chun et al. (Int J Rock Mech Min Sci 46:649–658, 2008) was used to develop these models. The parameters of the database were the depth, the weightings of the RMR system related to the uniaxial compressive strength, the rock quality designation, the joint spacing, the joint condition, the groundwater condition and the discontinuity orientation adjustment, the RMR and the deformation modulus. As a modelling tool the R program environment was used to apply these advanced techniques. Several algorithms were tested and analysed using different sets of input parameters. It was possible to develop new models to predict the rock deformation modulus and the RMR with improved accuracy and, additionally, allowed to have an insight of the importance of the different input parameters.

Conservation and New Construction Solutions in Rammed Earth

The conservation and rehabilitation of several sites of cultural heritage and of the large housing stock built from rammed earth requires adopting intervention techniques that aim at their repair or strengthening. The present work discusses the main causes of the decay of rammed earth constructions. The intervention techniques used to repair cracks and lost volumes of material are also discussed. Regarding the strengthening of rammed earth walls, the discussion is focused on the techniques that improve the out-of-plane behaviour. Special attention is given to the injection of mud grouts for crack repair in rammed earth walls, including the presentation of the most recent developments on the topic, namely regarding their fresh-state rheology, hardened-state strength and adhesion. Finally, the use of the rammed earth is discussed as a modern building solution. In addition, several typical techniques for improving rammed earth constructions are discussed, aiming at adequate those to modern demands. In addition, the alkaline activation of fly ash is presented and discussed as a novel improvement technique.

Luiz Bandeira Bridge: Assessment of a Historical Reinforced Concrete (RC) Bridge

The Luiz Bandeira Bridge is located along the Portuguese national road EN333-3, breaching the valley of the Vouga River, just northeast of the small village Sejães, in the district of Oliveira de Frades. It is considered to be the oldest concrete bridge in use in Portugal, and one of the oldest in Europe. Since this bridge is at risk of disappearing due to a construction of a dam, the Department of Civil Engineering of the University of Minho decided to launch a comprehensive study of Luiz Bandeira Bridge, in an attempt to preserve the memory of the past cataloguing the heritage for future reference. These studies include historical, geometric, and damage surveys; the physical and chemical characterization of existing structural materials; the assessment of the reinforcement detailing; and dynamic characterization by determining the main frequencies and vibration modes and safety level. This work presents a comprehensive overview of the most important results of these studies.

Increasing the reaction kinetics of alkali-activated fly ash binders for stabilisation of a silty sand pavement sub-base

The paper addresses several options to improve the reaction kinetics of alkali-activated low-calcium fly ash binders for soil stabilisation in road platforms. For that purpose, an experimental programme was established to assess the strength evolution, with time, of different binders, based on ash, lime, sodium chloride and alkali solutions, applied in the stabilisation of a silty sand. The tests included unconfined compression strength tests, triaxial tests and seismic wave measurements performed at different curing periods. The results were compared with a binder made of Portland cement and a commercial additive specifically designed for soil stabilisation in road applications. The activated ash mixtures with lime were the most performing producing a significant increase in the reactions development and, consequently, in the strength gain rate. The sodium chloride significantly improved the lime and lime-ash mixtures, but provided only a slight improvement in the activated ash mixtures.

Truncated gaussian simulation to map the spatial heterogeneity of rock mass rating

This research was supported by the Chilean Commission for Scientific and Technological Research (CONICYT), through Projects CONICYT/FONDECYT/REGULAR/No 1130085 and CONICYT PIA Anillo ACT1407, and by Innova Chile CORFO 11IDL2-10630.

Application of Data Mining Techniques for the Development of New Rock Mechanics Constitutive Models

Data Mining (DM) techniques have been successfully used in many fields and more recently also in geotechnics with good results in different applications. They are adequate as an advanced technique for analysing large and complex databases that can be built with geotechnical information within the framework of an overall process of Knowledge Discovery in Databases (KDD). A KDD process is carried out in the context of rock mechanics using the geotechnical information of two hydroelectric schemes built in Portugal and at DUSEL (Deep Underground Science and Engineering Laboratory). The purpose was to find new models to evaluate strength and deformability parameters and also empirical geomechanical indexes. Databases of geotechnical data were assembled and DM techniques used to analyse and extract new and useful knowledge. The procedure allowed developing new, simple, and reliable models for geomechanical characterization using different sets of input data which can be applied in different situations of information availability.

Improvement of a clayey soil with alkali activated low-calcium fly ash for transport infrastructures applications

The improvement of geotechnical properties is often achieved by the addition of traditional binders, such as cement or lime. However, the use of such binders implies a considerable financial and environmental cost that needs to be mitigated. An unconventional solution, similar to cement in terms of performance but more environmentally friendly, consists in the use of binders made from alkaline activated industrial residues. The technique consists on the activation of raw materials (such as fly ash or blast furnace slag) rich in Si, Al, or even Ca, with high pH alkaline solutions. The present work was developed aiming the possible stabilisation, using different fly ash contents, of a clayey soil with sand. The activator solution was composed of sodium hydroxide and sodium silicate. The extended experimental campaign included unconfined compressive strength (UCS), California Bearing Ratio (CBR), pulse velocity tests and triaxial tests to assess the geomechanical improvement induced by the new binder. As a mean of comparison, the experimental campaign included also the stabilisation of the same soil with either cement or lime. The obtained data indicates that the use of alkaline activation as a soil stabilisation technique provides competitive geomechanical results, when compared with those obtained with traditional binders.

Prediction of the mechanical properties of granites under tension using DM techniques

This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633.

Life cycle assessment of retaining wall backfilled with shredded tires

PurposeThis life cycle assessment (LCA) study compares energy consumption, greenhouse gas emissions, and environmental damages for two methods of constructing retaining structures, a traditional method involving a retaining wall backfilled with sand, and an alternative method involving a retaining wall backfilled with shredded tires.MethodsTaking into account the extraction and production of the used construction materials, loading, transport and installation, the cumulative energy demand (CED), global warming potential (GWP), acidification potential, Human Health Criteria Air-mobile, aquatic eutrophication potential, ozone depletion potential, and smog potential is determined for each construction method. The seven environmental impact categories are calculated using the software tool, ATHENA® Environmental Impact Estimator (ATHENA® EIE) for Buildings v5.2.0118.Results and discussionThe seven impact categories were reduced significantly by using shredded tires as retaining wall backfill; this is due to the decrease in the amounts of concrete, reinforcing steel, and fuel quantity consumed by building machines and vehicles transporting construction materials.ConclusionsThe study concludes that in all examined impact categories alternative method provides a larger environmental benefit than the traditional method. Also, the results clearly demonstrate that the use of shredded tires is very effective as a sustainable alternative to retaining structures.