the behavior of partially saturated soils is determined by the characteristics of their macro porous structure. the matrix suction is an additional fundamental variable in its response to deformation under variable mo...
Openings in rock play a significant role in the performance of rock related structures. the well-established knowledge in this area can contribute to the engineering practices, for example, underground space design, p...
In the current state of practice for the design of geotechnical projects, the extensive reliance on empirical correlations to obtain design parameters sometimes fails to capture realistic soil behaviour, and in other ...
the need for deeper urban excavations has imposed to geotechnical engineers the challenge of balancing high horizontal forces with occurrence of minimum displacements in soil as well as in the structures nearby. In ma...
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ISBN:
(纸本)9780429446924;9781138332034
the need for deeper urban excavations has imposed to geotechnical engineers the challenge of balancing high horizontal forces with occurrence of minimum displacements in soil as well as in the structures nearby. In many cases, a tied-back earth retaining wall is the recommended technical solution. the use of ground anchorage, as a direct extension of the rock anchoring technique, is intensely executed throughout the world. this work aims to evaluate a hydromechanical geotechnical problem solving the coupling between soil mass and water in the tied-back wall system. the safety factor of the tied-back wall and the displacement field generated by the construction of the retaining wall system are analyzed through the finite element method. the saturated cohesive soil is modeled by the Mohr-Coulomb constitutive law and effects due to variations of width and depth of the wall, anchors inclination and bulbs stiffness are also considered within a parametric study.
the topic of vibrations induced by rail traffic has received a special attention from the scientific community over the last decades. Nowadays, such thematic is faced as a public health concern. thus, procedures to mi...
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ISBN:
(纸本)9780429446924;9781138332034
the topic of vibrations induced by rail traffic has received a special attention from the scientific community over the last decades. Nowadays, such thematic is faced as a public health concern. thus, procedures to minimize the discomfort caused by an efficient railway network have to be proposed. In this paper a preliminary numerical study is presented about the mitigation of vibrations based on the introduction of a set of inclusions in the ground, parallel to the railway track. Analyses in space-frequency, and in frequency-wavenumber domains allowed concluding that the ground wave-propagation is strongly affected by the inclusions' presence. Based on that numerical study, theoretical simple equations were derived and they are here proposed in order to support the engineering design of this kind of mitigation measure.
In this paper, a numerical study of the stress state evolution in the ground induced by the railway traffic is presented. the numerical models were developed considering two types of railway tracks: ballasted and ball...
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ISBN:
(纸本)9780429446924;9781138332034
In this paper, a numerical study of the stress state evolution in the ground induced by the railway traffic is presented. the numerical models were developed considering two types of railway tracks: ballasted and ballastless tracks. Both structures were modelled in order to evaluate the differences obtained in terms of stresses under two different loading conditions: conventional passenger train (Alfa Pendular) and a freight train. the influence of the train speed and track irregularities were also studied. the numerical models were developed considering the 2.5D formulation based on FEM-PML approach. these results are a contribution to a better understanding the dynamic response of different track systems under distinct traffic scenarios and also to evaluate the comparative performance of the two systems.
numerical noise, in the form of high frequency acceleration spikes, may become a major obstacle to the prediction of peak seismic ground acceleration and short period spectral accelerations. this problem is examined h...
Although numerical simulations of flexible rockfall protection fences are common today, evaluating the reliability of such simulations remains a challenge. this contribution provides insight into and discusses certain...
the reinforcement of railway track foundations, through injection of binders, without the need of removal of track components (i.e. rails, sleepers and ballast) has many advantages compared to traditional approaches, ...
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ISBN:
(纸本)9780429446924;9781138332034
the reinforcement of railway track foundations, through injection of binders, without the need of removal of track components (i.e. rails, sleepers and ballast) has many advantages compared to traditional approaches, which normally are more complex, costly and strongly affect train operations. To contribute to a deeper understanding of issues associated with soil-binder column reinforcements, numerical studies were developed to analyse and compare different column layouts and to assess the effect of such reinforcements on the dynamic train-track interaction. To that aim, two three-dimensional numerical programs were used. Aspects of the train-track interaction and values of stresses and displacements on the track and trackbed layers are analysed and discussed. the results suggest that in similar problems of track platforms with uneven track stiffness, it is important to take into account the non-linear elastic behaviour of the ballast to obtain a more accurate three-dimensional load distribution.
Yielding elements are installed and embedded in the lining segments in tunneling through squeezing ground. this has been proved to be an effective measure to control convergence, provide stability and allow higher adv...
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ISBN:
(纸本)9780429446924;9781138332034
Yielding elements are installed and embedded in the lining segments in tunneling through squeezing ground. this has been proved to be an effective measure to control convergence, provide stability and allow higher advancing rates. Although it is recognized that these practical measures are highly effective in providing tunnel stability, there is no well-established method to transfer and extend these beneficial effects into the design. this paper presents a series of numerical analyses where different modelling approaches are used, based on FE method. Results are presented and compared to those from the actual measurements. Special spring elements were included in the model to represent the yielding elements. A 2D plain strain approach is compared with a full 3D model, where a detailed construction sequence was established. Interfaces in the lining-rock contact and time evolution of the shotcrete properties were also included in the model.
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