http://repositorio.lnec.pt:8080/jspui/handle/123456789/48 Fri, 06 Mar 2026 10:11:27 GMT 2026-03-06T10:11:27Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017636 Implementation of subloading constitutive models in Material Point Methods Pereira, C. This document describes the work developed in the short term scientific mission, STSM, of the COST TU1202, entitled Implementation of subloading constitutive models in material point methods, hosted by Dr. Phil Vardon, in the Technical University of Delft, TU Delft. A dynamic version of the material point method, MPM, in two-dimension was programmed, with the computer language Fortran. An elastoplastic subloading soil model with anisotropy, cyclic behaviour and structure was implemented in the program. The constitutive model was integrated using an explicit algorithm. Fri, 01 Jan 2016 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017636 2016-01-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017579 Test conditions influence on thermal conductivity and contact conductance of sand at transient state Aljundi, K.; Pereira, C.; Vieira, A.; Maranha, J. R.; Lapa, J.; Cardoso, R. The proper assessment of soil thermal properties, such as thermal conductivity, assumes a particular relevance for the design of Ground Source Heat Pump systems, as it determines the heat transfer and the energy efficiency design. Multiple methods can be used for thermal conductivity estimation, however significant scatters in measurements are often reported when using different (or even the same) methods. This work presents a detailed study of the thermal conductivity and the thermal contact conductance of a reference sand tested in transient conditions, analyzing the effect of several factors, such as the heating time, degree of saturation, soil density, temperature and heat flux intensity, on thermal conductivity measurements for dry state or fully saturated conditions. To avoid measurement errors and heterogeneity effects, only three samples were prepared with different compaction ratios, and systematically tested in dry and fully saturated conditions, under different control variables (temperature, testing time, and injected heat flux). Two analytical methods based on the line source solution were used to estimate soil thermal conductivity and to assess the probe-to-soil thermal contact conductance. Significant relationships were obtained between thermal conductivity and soil state conditions and testing variables, highlighting that a heating time longer than the one usually recommended in the standards is clearly needed. Finally, this study uses measured temperature values to determine the probe-to-soil thermal contact conductance, indicating its relevance in soil thermal conductivity estimation. Mon, 01 Jan 2024 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017579 2024-01-01T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017578 The practice of testing ground nails Carvalho, M. R. Balkema The soil nailing construction technique is often used to stabilise a ground mass by installing reinforcing elements (nails). The European Standard EN 14490:2010 defines general principles for execution, supervision, testing and monitoring of soil nailing. This paper presents tests results obtained in several ground nails executed in recent geotechnical works. These tests were carried out in sacrificial nails, before and during the works. As shown in this paper, the execution of the nails, the test system and test procedures affect their results quality. Thus, a critical analysis of the tests results is performed to assess the behaviour of the ground nails, framed by EN 14490:2010, in accordance with the design and contract specifications. Tue, 27 Aug 2024 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017578 2024-08-27T00:00:00Z http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017505 Métodos de ensaio para verificação da carga instalada em ancoragens de serviço Carvalho, M. R.; Juvêncio, E. 18º Cong Nacional de Geotecnia-Universidade de Évora As ancoragens no terreno em estruturas de contenção, apresentam-se como “obras vivas”, carecendo de inspeção e de manutenção periódicas. A carga nas ancoragens pode variar com o tempo, nomeadamente para valores inferiores aos da blocagem, geralmente na presença de problemas associados com fenómenos de corrosão da armadura ou por redução dos impulsos do terreno, ou para valores superiores por aumento das solicitações do terreno, por exemplo. O ensaio de verificação da carga instalada realiza-se em ancoragens de obra, em serviço, com o objetivo de esclarecer o respetivo comportamento mecânico e de fluência, entre outros aspetos. Neste contexto, avaliar a magnitude da carga instalada nas ancoragens é fundamental para garantir a longevidade e segurança das obras. Entre os ensaios que permitem avaliar a carga instalada nas ancoragens, destacam-se: o ensaio de verificação da tração (EVT), cuja metodologia se desenvolveu no LNEC, e o ensaio do tipo Lift-Off. Neste artigo apresenta-se uma descrição dos fatores responsáveis pela variação da carga em ancoragens no terreno, do ensaio EVT e de Lift-Off, bem como resultados de ensaios de obra, sua análise e considerações. Sun, 14 May 2023 00:00:00 GMT http://repositorio.lnec.pt:8080/jspui/handle/123456789/1017505 2023-05-14T00:00:00Z