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A Brazilian Tensile Strength (BTS) laboratory test for meta-andesite was modeled using a Finite/Discrete Element Method (FDEM or FEM-DEM). These hybrid methodologies allow modeling the transition from continuous to discontinuous that happens on mechanical tests of rock samples. This article presents the calibration and the simulation of BTS tests using some parameters previously calibrated on UCS modeling of the same material. Irazu, a two-dimensional software developed by Geomechanica, was used to simulate the tests based on the tensile strength and the fracture pattern. The model shows that, in BTS test simulation, the mode II (shear) happens mainly on the rock-platen contact. The mode I (traction) rules the fractures on the BTS test as observed in laboratory tests. The model represents, with great fidelity, the results obtained in the physical test.

Finite/discrete element methods (FDEM) are hybrid numerical models that use algorithms to analyze the transition from continuous to discontinuous. This type of formulation allows modeling physical laboratory tests with greater proximity to reality. This article proposes to simulate the average behavior of a uniaxial compression test campaign. The tests were modeled and calibrated based on the strength and the fracture pattern using Geomechanica Inc. Irazu two-dimensional software. The simulated results were analyzed by the mean standard deviation of approximately 3000 elements in the middle third of the model, the same region where the clip gages are located in the physical test. The obtained results show that FDEM can replicate the laboratory test with great similarity.

The present study is focused on mining planning with an emphasis on the graph theory model proposed by Lerchs-Grossmann. The original paper published by Lerchs-Grossmann about determination of optimum final pit does not report the computational algorithm to solve the problem. This paper discusses and presents an algorithm based on the maximum flow graph computational work from Ford Fulkerson. The main steps for solving the problem and the results of the two-dimensional models are discussed. ResumoO presente trabalho tem como foco o planejamento de lavra com ênfase no modelo da teoria dos grafos de Lerchs-Grossmann. O trabalho publicado pelo autor em que se discute o teorema para a determinação da cava final ótima não apresenta o algoritmo computacional para resolver o problema. Esse trabalho apresenta um algoritmo baseado no fluxo máximo dos grafos como discutido no trabalho computacional de Ford Fulkerson. Serão apresentados os passos principais para resolução do problema e os resultados dos testes realizados para modelos bidimensionais. Palavras-chave: Lerchs-Grossmann; cava final; grafo; Ford Fulkerson.A proposal to find the ultimate pit using Ford Fulkerson algorithm Uma proposta para determinar cava final utilizando Ford Fulkerson

Stope design optimisation defines three-dimensional extraction volumes aiming to maximise cashflows, subject to geotechnical and operational constraints. Available stope layout methods are deterministic, failing to account for grade uncertainty and variability that affect stope locations and sizes, as well as value. A two-stage stochastic integer programming model for stope design optimisation is proposed, integrating grade uncertainty quantified through geostatistical simulations, level allocation, variable stope and pillar sizes for different geotechnical zones, and development costs. An application at an underground gold mine employing sublevel open stoping highlights the integration and management of grade uncertainty to define risk-resilient stope design.

Drilling and stabilizing oil wells are important technological challenges for developing the Brazilian Pre-Salt deposits due to creep behaviour of salt rocks, which results in well closure and collapse. The objectives of this work are to analyse the currently used creep models and to propose a new empirical model that comprehends the three creep stages. This work suggests that a deep interpretation of Burger's rheological model, based on the physical parameters of creep phenomenon, should be investigated. The problem of the explicit presence of time in creep strain rate models is discussed. The new proposed model is able to reproduce models that describe the transient and the steady-state creep stages. However, its calibration should be careful, based on data from all these creep stages.Keywords: salt rock, oil drilling, creep models, rock mechanics. Resumo

BackgroundTo evaluate medical, economical and sociological variables underlying avoidable pediatric migration from Campania region.MethodsAnalysis of years 2006–2010 hospital discharge records, extracted from the archive of Regional Health Agency (ArSan), classified by Major Diagnostic Categories, Aggregate Clinical Codes, Discipline of dismissal, Local Health Authorities of residence, and age group 0–14 years (excluding those of healthy newborns). Sociological variables were evaluated by questionnaires.ResultsA total of 68,316 hospital discharge records were released by extra-regional structures. Major diagnostic categories and Discipline of dismissal indicated that the most implicated diseases (nervous system and mental disorders, hematology-oncology, and bone diseases) were not always of very high complexity. The total cost paid by the Campania Region was 124.700.000 Euros. The need for more specialized hospital pediatric units and/or with more pediatric subspecialties in the native region was pointed out by most of the self-administered questionnaires.ConclusionsPediatric migration is an important phenomenon with evident implications. The identification of the most concerned sub-specialties here reported can give useful information aiming to assist in the improvement of the existing pediatric resources in Campania region in the wider context of the national global child health advancement.

RESUMO: O algoritmo híbrido de elementos fintos e discretos (FDEM) permite analizar a transição do comportamento mecânico continuo para o descontinuo. Tatone e Grasselli (2015) propõem a utilização de uma campanha de ensaios mecânicos em rochas como: Determinação da Resistência à Compressão Uniaxial (R.C.U), Determinação da Resistência à Compressão Diamaetral e ensaios de Determinação da Resistência à compressão triaxial para a calibração de rochas. A calibração é realizada simulando os ensaios de laboratório utilizando como objetivo a sua resistência máxima e o seu padrão de fraturamento. O software utiliza um algortimo em Python para obter a tensão de ruptura baseado na reação dos pratos de aplicação de força em um corpo de prova. A proposta deste artigo é investigar o comportamento mecânico da amostra em seu terço médio, onde são medidas as deformações nos ensaios laboratoriais. Avaliando o desvio padrão médio das tensões e deformações principais em conjunto com o número de elementos utilizados para esta avaliação. Os resultados apresentam convergência para numeros de elementos maiores que 3000 elementos.