Prevention in underground construction with sequential excavation method

This paper aims to describe the Sequential Excavation Method, used for excava-tion in underground works, as well as the related risks and preventive measures. This method has characteristics that differentiate it from other tunnelling techniques: it uses a larger number of workers and equipment; it has a high concurrency of tasks with various workers and equip-ment quite exposed to hazards; and it uses many potentially aggressive chemicals. Firstly, it is given a broad overview of this issue. Afterwards, it will be presented the results of a survey to a sample of experienced technicians, aimed at gauging the relevance of a set of guidelines relat-ing to the design and work phases, applicable to the domestic market and prepared following technical visits to works abroad.

Localization in underground tunnels

Positioning technologies are becoming ubiquitous and are being used more and more frequently for supporting a large variety of applica- tions. For outdoor applications, global navigation satellite systems (GNSSs), such as the global positioning system (GPS), are the most common and popular choice because of their wide coverage. GPS is also augmented with network-based systems that exploit existing wireless and mobile networks for providing positioning functions where GPS is not available or to save energy in battery-powered devices. Indoors, GNSSs are not a viable solution, but many applications require very accurate, fast, and exible positioning, tracking, and navigation functions. These and other requirements have stim- ulated research activities, in both industry and academia, where a variety of fundamental principles, techniques, and sensors are being integrated to provide positioning functions to many applications. The large majority of positioning technologies is for indoor environments, and most of the existing commercial products have been developed for use in of ce buildings, airports, shopping malls, factory plants, and similar spaces. There are, however, other spaces where positioning, tracking, and navigation systems play a central role in safety and in rescue operations, as well as in supporting speci c activities or for scienti c research activities in other elds. Among those spaces are underground tunnels, mines, and even underwater wells and caves. This chapter describes the research efforts over the past few years that have been put into the development of positioning systems for underground tun- nels, with particular emphasis in the case of the Large Hadron Collider (LHC) at CERN (the European Organization for Nuclear Research), where localiza- tion aims at enabling more automatic and unmanned radiation surveys. Examples of positioning and localization systems that have been devel- oped in the past few years for underground facilities are presented in the fol- lowing section, together with a brief characterization of those spaces’ special conditions and the requirements of some of the most common applications. Section 5.2 provides a short overview of some of the most representative research efforts that are currently being carried out by many research teams around the world. In addition, some of the fundamental principles and tech- niques are identi ed, such as the use of leaky coaxial cables, as used at the LHC. In Section 5.3, we introduce the speci c environment of the LHC and de ne the positioning requirements for the envisaged application. This is followed by a detailed description of our approach and the results that have been achieved so far. Some last comments and remarks are presented in a nal section.

Methodology for real-time adaptation of tunnels support using the observational method

The observational method in tunnel engineering allows the evaluation in real time of the actual conditions of the ground and to take measures if its behavior deviates considerably from predictions. However, it lacks a consistent and structured methodology to use the monitoring data to adapt the support system in real time. The definition of limit criteria above which adaptation is required are not defined and complex inverse analysis procedures (Rechea et al. 2008, Levasseur et al. 2010, Zentar et al. 2001, Lecampion et al. 2002, Finno and Calvello 2005, Goh 1999, Cui and Pan 2012, Deng et al. 2010, Mathew and Lehane 2013, Sharifzadeh et al. 2012, 2013) may be needed to consistently analyze the problem. In this paper a methodology for the real time adaptation of the support systems during tunneling is presented. In a first step limit criteria for displacements and stresses are proposed. The methodology uses graphics that are constructed during the project stage based on parametric calculations to assist in the process and when these graphics are not available, since it is not possible to predict every possible scenario, inverse analysis calculations are carried out. The methodology is applied to the “Bois de Peu” tunnel which is composed by two tubes with over 500 m long. High uncertainty levels existed concerning the heterogeneity of the soil and consequently in the geomechanical design parameters. The methodology was applied in four sections and the results focus on two of them. It is shown that the methodology has potential to be applied in real cases contributing for a consistent approach of a real time adaptation of the support system and highlight the importance of the existence of good quality and specific monitoring data to improve the inverse analysis procedure.

Portuguese strengths and fragilities on safety and health practices

Despite improvements over the years, accidents continue to be a scourge in the construction sector, leading to an increase in the number of journal articles addressing the issue, in an attempt to help construction industry to increase safety performance [1]. This paper aims to, helping construction industry and particulary tunneling community, describe the Portuguese approach to most typical health and safety problems in underground excavations performed with the Sequential Excavation Method (SEM). The article will address various topics, from safety management and organizational practices, to collective and personal protection equipment, to emergency planning. nt problems in safety and health matters are similar to several other countries, the paper will expose a compilation of Portuguese best practices used to solve that problems. This enunciation of best practices describes experience from most important and recognized Project Owners and Contractors in Portugal. In a second phase it will be analysed Portuguese weaknesses, identifying preventive measures, and their comparative importance, that should be adopted in Portugal in order to reduce accidents and health diseases.

Combining data mining and evolutionary computation for multi-criteria optimization of earthworks

Earthworks tasks aim at levelling the ground surface at a target construction area and precede any kind of structural construction (e.g., road and railway construction). It is comprised of sequential tasks, such as excavation, transportation, spreading and compaction, and it is strongly based on heavy mechanical equipment and repetitive processes. Under this context, it is essential to optimize the usage of all available resources under two key criteria: the costs and duration of earthwork projects. In this paper, we present an integrated system that uses two artificial intelligence based techniques: data mining and evolutionary multi-objective optimization. The former is used to build data-driven models capable of providing realistic estimates of resource productivity, while the latter is used to optimize resource allocation considering the two main earthwork objectives (duration and cost). Experiments held using real-world data, from a construction site, have shown that the proposed system is competitive when compared with current manual earthwork design.

Modern optimization in earthwork construction

Earthworks tasks are often regarded in transportation projects as some of the most demanding processes. In fact, sequential tasks such as excavation, transportation, spreading and compaction are strongly based on heavy mechanical equipment and repetitive processes, thus becoming as economically demanding as they are time-consuming. Moreover, actual construction requirements originate higher demands for productivity and safety in earthwork constructions. Given the percentual weight of costs and duration of earthworks in infrastructure construction, the optimal usage of every resource in these tasks is paramount. Considering the characteristics of an earthwork construction, it can be looked at as a production line based on resources (mechanical equipment) and dependency relations between sequential tasks, hence being susceptible to optimization. Up to the present, the steady development of Information Technology areas, such as databases, artificial intelligence and operations research, has resulted in the emergence of several technologies with potential application bearing that purpose in mind. Among these, modern optimization methods (also known as metaheuristics), such as evolutionary computation, have the potential to find high quality optimal solutions with a reasonable use of computational resources. In this context, this work describes an optimization algorithm for earthworks equipment allocation based on a modern optimization approach, which takes advantage of the concept that an earthwork construction can be regarded as a production line.

Earthwork optimization system for sustainable highway construction

In highway construction, earthworks refer to the tasks of excavation, transportation, spreading and compaction of geomaterial (e.g. soil, rockfill and soil-rockfill mixture). Whereas relying heavily on machinery and repetitive processes, these tasks are highly susceptible to optimization. In this context Artificial Intelligent techniques, such as Data Mining and modern optimization can be applied for earthworks. A survey of these applications shows that they focus on the optimization of specific objectives and/or construction phases being possible to identify the capabilities and limitations of the analyzed techniques. Thus, according to the pinpointed drawbacks of these techniques, this paper describes a novel intelligent earthwork optimization system, capable of integrating DM, modern optimization and GIS technologies in order to optimize the earthwork processes throughout all phases of design and construction work. This integration system allows significant savings in time, cost and gas emissions contributing for a more sustainable construction.

Rockburst laboratory tests database - Application of data mining techniques

Rockburst is characterized by a violent explosion of a block causing a sudden rupture in the rock and is quite common in deep tunnels. It is critical to understand the phenomenon of rockburst, focusing on the patterns of occurrence so these events can be avoided and/or managed saving costs and possibly lives. The failure mechanism of rockburst needs to be better understood. Laboratory experiments are undergoing at the Laboratory for Geomechanics and Deep Underground Engineering (SKLGDUE) of Beijing and the system is described. A large number of rockburst tests were performed and their information collected, stored in a database and analyzed. Data Mining (DM) techniques were applied to the database in order to develop predictive models for the rockburst maximum stress (σRB) and rockburst risk index (IRB) that need the results of such tests to be determined. With the developed models it is possible to predict these parameters with high accuracy levels using data from the rock mass and specific project.

Tunnel engineering – influence of the type and the quantity of measurements in the back analysis of geomechanical parameters

The monitoring data collected during tunnel excavation can be used in inverse analysis procedures in order to identify more realistic geomechanical parameters that can increase the knowledge about the interested formations. These more realistic parameters can be used in real time to adapt the project to the real structure in situ behaviour. However, monitoring plans are normally designed for safety assessment and not especially for the purpose of inverse analysis. In fact, there is a lack of knowledge about what types and quantity of measurements are needed to succeed in identifying the parameters of interest. Also, the optimisation algorithm chosen for the identification procedure may be important for this matter. In this work, this problem is addressed using a theoretical case with which a thorough parametric study was carried out using two optimisation algorithms based on different calculation paradigms, namely a conventional gradient-based algorithm and an evolution strategy algorithm. Calculations were carried for different sets of parameters to identify several combinations of types and amount of monitoring data. The results clearly show the high importance of the available monitoring data and the chosen algorithm for the success rate of the inverse analysis process.

Coordenação de segurança em obra: metodologia, técnicas e ferramentas

Dissertação de mestrado integrado em Engenharia Civil

Modelação numérica de túneis com consideração explícita das heterogeneidades do maciço

Dissertação de mestrado integrado em Engenharia Civil

Development of an intelligent earthwork optimization system

Tese de Doutoramento em Engenharia Civil.

Arquitetura e paisagem monásticas no território bracarense: o caso de Dume (S. Martinho)

Dissertação de mestrado em Arqueologia

A new sector of Via XVII Necropolis in Bracara Augusta: the High Empire phase

Between 2008 and 2009 a preventive excavation supervised by the Unit of Archaeology of the University of Minho was conducted in an area with approximately 5000 square meters allowing the identification of a wide sector of the Via XVII necropolis, which is one of the five roman necropolises known to have existed in Bracara Augusta. The findings enabled us to define a typological framework related with incinerations, to understand the internal organization of the necropolis and recover the ritual marks of the funerary practices between the first century BC and the second century AD.

“Safety and health” as a criterion in the choice of tunneling method

Risk management is of paramount importance in the success of tunnelling works and is linked to the tunnelling method and to the constraints of the works. Sequencial Excavation Method (SEM) and Tun-nel Boring Machine (TBM) method have been competing for years. This article, part of a wider study on the influence of the â Safety and Healthâ criterion in the choice of method, reviews the existing literature about the criteria usually employed to choose the tunnelling method and on the criterion â Safety and Healthâ . This crite-rion is particularly important, due to the financial impacts of work accidents and occupational diseases. This article is especially useful to the scientific and technical community, since it synthesizes the relevance of each one of the choice criteria used and it shows why â Safety and Healthâ must be a criterion in the decision mak-ing process to choose the tunnelling method.