Relatório de estágio em farmácia comunitária

Relatório de estágio realizado no âmbito do Mestrado Integrado em Ciências Farmacêuticas, apresentado à Faculdade de Farmácia da Universidade de Coimbr

Estimation of effective stress parameter of unsaturated soils by using artificial neural networks

WOS: 000257088900004Great efforts are required for determination of the effective stress parameter chi, applying the unsaturated testing procedure, since unsaturated soils that have the three-phase system exhibit complex mechanical behavior. Therefore, it seems more reasonable to use the empirical methods for estimation of chi. The objective of this study is to investigate the practicability of using artificial neural networks (ANNs) to model the complex relationship between basic soil parameters, matric suction and the parameter chi. Five ANN models with different input parameters were developed. Feed-forward back propagation was applied in the analyses as a learning algorithm. The data collected from the available literature were used for training and testing the ANN models. Furthermore, unsaturated triaxial tests were carried out under drained condition on compacted specimens. ANN models were validated by a part of data sets collected from the literature and data obtained from the current study, which were not included in the training phase. The analyses showed that the results obtained from ANN models are in satisfactory agreement with the experimental results and ANNs can be used as reliable tool for prediction of chi. Copyright (C) 2007 John Wiley & Sons, Ltd

The consolidation characteristics of an unsaturated compacted soil

WOS: 000253213000011The compacted soils are extensively employed as mineral liners or a sealing system, constructed under municipal solid waste and other containment hazardous materials to prevent or minimize the leakage of pollutant liquids and gases into ground water and sublayers. This article presents a detailed experimental study on settlement characteristics, which are required for the construction of a sealing system. For the experimental study where a compacted unsaturated soil taken from Adana in Turkey has been used, a special equipped consolidation cell has been designed and constructed. The matric suction adopted as independent stress-state variables has been controlled by using the axis translation technique. The consolidation tests have been performed under constant matric suction. Furthermore, the pressure plate tests for various net vertical stresses have been conducted. The test results have indicated that the settlement characteristics of a compacted soil as mineral liners and covers are highly affected by matric suction. The water retention capacity of mineral liners, an important factor for hydraulic conductivity, also changes with the vertical load. The compressibility decreases as the matric suction increases. It has been observed that there exists an exponential relationship between the compressive indexes (C-t, D-t) and matric suction

Influence of matric suction on shear strength behavior of a residual clayey soil

In this paper, the shear strength with respect to the matric suction of unsaturated soils was studied. For this purpose, unsaturated triaxial testing procedures were applied to the undisturbed residual soil specimens. An apparatus for performing triaxial tests was designed and constructed. In the tests, matric suction was controlled by using the axis translation technique, and pore water volume changes were measured by means of a volume change transducer with 10 -8 m 3 sensitivity. The test results indicated that the matric suction contributes to the shear strength of unsaturated soil specimens, and this contribution called suction strength varies non-linearly with respect to the matric suction. The logarithmic model needing to know the air-entry value and the internal friction angle of a soil specimen for prediction of the suction strength were presented and compared with the test results. It was found that suction strength values predicted from the proposed model were in satisfactory agreement with the experimental results. © 2007 Springer-Verlag

Influence of matric suction on shear strength behavior of a residual clayey soil

WOS: 000251142500017In this paper, the shear strength with respect to the matric suction of unsaturated soils was studied. For this purpose, unsaturated triaxial testing procedures were applied to the undisturbed residual soil specimens. An apparatus for performing triaxial tests was designed and constructed. In the tests, matric suction was controlled by using the axis translation technique, and pore water volume changes were measured by means of a volume change transducer with 10(-8) m(3) sensitivity. The test results indicated that the matric suction contributes to the shear strength of unsaturated soil specimens, and this contribution called suction strength varies non-linearly with respect to the matric suction. The logarithmic model needing to know the air-entry value and the internal friction angle of a soil specimen for prediction of the suction strength were presented and compared with the test results. It was found that suction strength values predicted from the proposed model were in satisfactory agreement with the experimental results

Critical-state parameters of an unsaturated residual clayey soil from Turkey

This paper deals with the evaluation of the critical-state parameters with respect to the matric suction for saturated and unsaturated undisturbed residual clayey soils from Turkey. In order to conduct the unsaturated triaxial compression testing procedures a conventional triaxial compression apparatus was redesigned. The data for critical-state conditions from these tests are presented with respect to matric suction, based on the critical-state parameters of M, qo, ?, ?, which is commonly proposed by many authors. The critical state of the unsaturated samples is compared with that of the saturated samples. This experimental study has demonstrated that matric suction has no influence on parameters of M and ?. The parameters of M and ? are approximately 0.85 and 0.074 respectively for saturated and unsaturated conditions. The relationships between matric suction (ua - uw) and the intercepts qo and ? have been observed as nonlinear, and thus they can be defined as a function of matric suction (ua - uw). Furthermore, a method is developed to predict the intercepts q0 according to matric suction for unsaturated clayey soils. © 2007 Elsevier B.V. All rights reserved

Adaptive neuro-fuzzy modeling for the swelling potential of compacted soils

WOS: 000274180900013This paper aims to present the usability of an adaptive neuro fuzzy inference system (ANFIS) for the prediction swelling potential of the compacted soils that are important materials for geotechnical purposes such as engineered barriers for municipal solid waste, earth dams, embankment and roads. In this study the swelling potential that is also one of significant parameters for compacted soils was modeled by ANFIS. For the training and testing of ANFIS model, data sets were collected from the tests performed on compacted soils for different geotechnical application in Nigde. Four parameters such as coarse-grained fraction ratio (CG), fine-grained fraction ratio (FG), plasticity index (PI) and maximum dry density (MDD) were presented to ANFIS model as inputs. The results obtained from the ANFIS models were validated with the data sets which are not used for the training stage. The analyses revealed that the predictions from ANFIS model are in sufficient agreement with test results

Critical-state parameters of an unsaturated residual clayey soil from Turkey

WOS: 000250657400001This paper deals with the evaluation of the critical-state parameters with respect to the matric suction for saturated and unsaturated undisturbed residual clayey soils from Turkey. In order to conduct the unsaturated triaxial compression testing procedures a conventional triaxial compression apparatus was redesigned. The data for critical-state conditions from these tests are presented with respect to matric suction, based on the critical-state parameters of M, q(0), Gamma, lambda, which is commonly proposed by many authors. The critical state of the unsaturated samples is compared with that of the saturated samples. This experimental study has demonstrated that matric suction has no influence on parameters of M and lambda. The parameters of M and lambda are approximately 0.85 and 0.074 respectively for saturated and unsaturated conditions. The relationships between matric suction (u(a)-u(w)) and the intercepts q(0) and Gamma have been observed as nonlinear, and thus they can be defined as a function of matric suction (u(a)-u(w)). Furthermore, a method is developed to predict the intercepts q(0) according to matric suction for unsaturated clayey soils. (c) 2007 Elsevier B.V. All rights reserved

An equation for predicting shear strength envelope with respect to matric suction

Determining the shear strength parameters of unsaturated soils generally involves costly, time-consuming and sophisticated testing programme. This paper proposes a new method for prediction of shear strength with respect to matric suction. The variation of shear strength with respect to matric suction is described by using the air-entry value and the internal friction angle of a soil specimen. The validity of the method is tested for a number of suction strength data available in the literature. The shear strengths with respect to matric suction obtained from the proposed method are in nicely good agreement with experimental results. © 2004 Elsevier Ltd. All rights reserved