Resumo em Inglês:

Abstract The continuous advancement in new materials and manufacturing processes enables innovative applications to emerge daily in the oil and gas sector. Among these, concrete extrusion technology, enhanced by plasticizer addition and reduced porosity, offers improved mechanical properties compared to conventional cementitious components. This article evaluates the technical feasibility of replacing high-alloy steel pipes with extruded concrete pipes for oil well casing. Using finite element analysis developed in Ansys®, four critical scenarios were evaluated: (i) radial tensile stresses associated with gas bubbles, ii) radial compressive stresses linked to pore pressure and formation fracturing, iii) axial tensile stresses due to string movement, and iv) axial tensile stresses related to casing string unlocking. Results indicate that extruded concrete pipes can safely withstand differential radial pressures of up to 1,000 psi, provided a minimum wall thickness of 100 mm is adopted. However, axial load simulations revealed critical limitations: maximum tensile stresses reached 96.6 MPa during lifting operations and 193.1 MPa during unlocking, both far exceeding the material’s tensile strength of 30 MPa. These findings demonstrate that, despite the material’s adequate performance under radial loading, extruded concrete pipes are unsuitable for axial loading conditions inherent to casing operations. Further research is recommended on hybrid or fiber-reinforced alternatives to enhance tensile resistance and extend the potential of concrete extrusion to downhole applications.

Resumo em Inglês:

Abstract One of the major challenges in Civil Engineering is the gradual search for more viable and efficient solutions to improve structural performance. In this case, Structural Engineering has been encouraged to create and develop materials and methods that allow for the production of more slender structures that are at the same time safe and economical. One of these solutions is structural optimization. This article addresses topological optimization in three-dimensional problems considering volume minimization based on a stress criterion. The method used is Evolutionary Structural Optimization (ESO) with the aid of the structural analysis software Salome-Meca®, via the Finite Element Method (FEM). For this, an algorithm in Python® programming language is implemented to be the input file of the free numerical analysis software Code-Aster® solver of Salome-Meca®. In the ESO process, underutilized elements of the structural system are removed, that is, elements whose stress have values lower than the maximum limit stress of the structure. This optimization is performed using a combination of two isotropic materials, with the aim of studying the influence of different constitutive models on the optimal topologies of the proposed problems, analyzing the topological structural behavior, as well as investigating how the mechanical and physical properties impact the final topology. Finally, based on the considerations and research in question, the optimization of composite structures is interesting because it obtains a more efficient structure that takes advantage of the positive complementary characteristics of two materials working together.

Resumo em Inglês:

Abstract The Last Planner System (LPS) is a collaborative production planning and control approach in lean construction that improves workflow reliability by converting work into reliable commitments and systematically learning from plan failures. Despite its demonstrated benefits internationally, LPS adoption in Sri Lanka remains limited and often partial, largely due to insufficient organizational and industry-level capacities. This study identifies the capacity requirements for full LPS implementation in the Sri Lankan construction industry and proposes practical capacity-building strategies to address them. Nine expert interviews were conducted using qualitative design and analyzed using qualitative content analysis in NVivo. Nineteen capacity requirements were identified across LPS planning horizons. They were classified as internal (e.g., lean/LPS knowledge, structured training, leadership and change management, communication practices and media, top-management support, and adequate human/technical resources) and external (e.g., client approval processes, external stakeholder support, industrial training capability, lean information infrastructure, and supportive legal and regulatory frameworks). Twenty-five strategies were developed to strengthen these capacities, emphasizing phase-based LPS training and coaching, leadership development, collaborative contract and procurement arrangements, and institutional support mechanisms (e.g., CPD programs and lean information portals). The resulting strategic framework provides an actionable roadmap for contractors, clients, and regulators to enable sustainable LPS deployment in Sri Lanka.

Resumo em Inglês:

Abstract The load transfer methods are important tools for predicting the behavior of the load-displacement curve for piles. Several studies indicate that these curves in single piles can be well represented by hyperbolic functions. In this context, this research aims to predict the load transfer curves in single piles using hyperbolic functions based on easily obtainable parameters and measurements. For this purpose, data from 48 instrumented single piles (driven and bored), executed in granular soil profiles and subjected to static load tests were collected, obtaining the parameters of hyperbolic curves that define the t-z and q-z load transfer curves. Correlations of the parameters of the hyperbolic curves with measurements from cone penetration tests (CPT) or standard penetration tests (SPT), pile geometry, initial geostatic stresses, and deformation parameters of the load transfer curves were performed. Validation indicated results converging to the proposed predictions, and in general, predictions based on CPT measurements, and using deformation parameters Ms and Mb showed more convergent results.

Resumo em Inglês:

Abstract The key-block theory enables the identification of stable and unstable blocks along the perimeter of underground excavations in hard rock. Monte Carlo simulation can be used to develop a probabilistic extension of the key-block theory. This article aims to examine the suitability of the reliability index as an interpretive tool for assessing block stability in analyses where variability is explicitly represented. A Monte Carlo simulator was implemented using the vector formulation of the key-block theory. In the simulations, variability in joint orientations is modeled with a spherical distribution, while strength variability is represented by a normal distribution. A first study showed that a lognormal model more appropriately represents the probabilistic distribution of the safety factor for the wall blocks in the studied case. This is due to the highly truncated probability density function of the Fischer distribution adopted for the orientation of the planes. A second study found that significant changes in block failure modes occur only under a large dispersion of joint orientations. A third study indicated that, for a roof block failing under self-weight, the required reinforcement level can be determined by verifying the consistency of the reliability index with international code criteria. The implemented simulator was validated through comparison with a commercial simulator. The developed tool offers advantages over the commercial reference, such as the direct calculation of the reliability index and the identification of the change in the failure mechanism that occurs for wide orientation dispersion.

Resumo em Inglês:

Abstract The equivalent frame method is widely used for the structural analysis of masonry buildings subjected to lateral loads. In this approach, masonry structural components are idealized as macro-elements, which consist of reticulated finite elements formulated to simulate the quasi-brittle behavior of masonry and its typical failure mechanisms. This study investigates a macro-element with a mixed force-based formulation applied to the modeling of structural masonry shear walls. The study is based on a previously developed macro-element for unreinforced masonry panels, using the Timoshenko beam theory, which adopts a uniaxial constitutive model for masonry and incorporates a non-linear shear hinge. The cross-sectional stiffness matrix is obtained through analytical integration, without fiber discretization. This macro-element is capable of reproducing the failure mechanisms of rocking, bed joint sliding, and diagonal cracking. The present study focuses on the enhancement of the macro-element through extensions to the original formulation and modifications to the non-linear solution procedure. The main contributions include the introduction of a tensile branch into the masonry constitutive law, as well as the incorporation of reinforcement through a fiber-based approach. In addition, modifications were introduced in the matrix representation of the cross-section force-deformation relationship, resulting in a more robust numerical scheme with improved convergence. The macro-element was applied to the numerical simulation of experimentally tested unreinforced and reinforced masonry shear walls, yielding results consistent with data reported in literature.

Resumo em Inglês:

Abstract Hydrogen sulfide (H2S) emissions from mining tailings dams pose persistent environmental and operational challenges due to their corrosiveness, toxicity, and intense odor. In a Brazilian mining complex, sulfate-reducing bacteria (SRB) associated with unoxidized ore and recirculated process water were identified as the primary source of H2S. Initial mitigation using a glutaraldehyde-based biocide temporarily suppressed microbial activity but proved unsustainable due to high dosing costs and the development of microbial resistance. Subsequently, sodium hypochlorite (NaClO) was tested as an oxidizing agent to chemically neutralize H2S before degassing. Laboratory and industrial-scale trials confirmed that NaClO, at an optimized dosage of 10 L/h, effectively eliminated odors within 10-20 minutes, with no reappearance over a 48-hour observation period and reducing odor complaints to zero, without compromising the process performance. This approach also reduced operational costs by 90% compared to the biocide. This case study highlights the benefits of integrating microbiological diagnostics with adaptive chemical strategies to establish a scalable, cost-effective solution for odor control in mining environments.

Resumo em Inglês:

Abstract This article presents the results of a mineral prospecting study of active stream sediment and alluvial sediment from the Araguari River, Minas Gerais, Brazil. Sediment samples were collected from the river's source to the Desemboque district, where, between the years 1743 and 1781, 1,500 kg of alluvial gold were extracted. Therefore, this study analyzed samples of alluvial sediments and active watercourses to identify potential mineralization zones in a region historically associated with gold deposits. Geochemical assays indicate Pt concentrations exceeding Clarke values, contrasting with relatively low gold (Au) levels. Correlations between Cu and Ag, as well as rare earth elements (Ce and La), suggest complex mineralization processes linked to regional lithology and hydrothermal activity. These findings expand the understanding of the Araguari basin’s metallogenic potential and highlight opportunities for future exploration targeting platinum group elements and associated metals.