Metamorfismo y deformación en la región de El Fuerte: su papel en la .. as well as local axial planar cleavages (S3–S4RF; S2–S3TF) in the hinges of these. TERMIUM® is the Government of Canada's terminology and linguistic data bank. Curso de MathCad Ejercicio Cálculo de la deformación axial Construir el diagrama de esfuerzo normal y calcular la deformación absoluta de la barra.


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Experimental assessment of the liquefaction resistance of calcareous biogenous sands Eimar A. Sandoval1 and Miguel A. Record Accepted for publications: Most liquefaction research has focused on silicate-based sands and not on other sand types, such as calcareous biogenous sands Calcareous sands are usually composed of skeletal or non-skeletal remains of marine organisms, with unique characteristics in deformacion axial of their mineralogy surface roughness, particle shape, crushability, and intraparticle porosity.

The unique characteristics of calcareous sands suggest that their geotechnical engineering behaviour can be substantially different compared to that of terrigenous sands, including their behaviour under seismic loading, which have not been very well studied This paper presents the results of an experimental programme aimed at studying the cyclic liquefaction resistance of uncemented calcareous biogenous sands retrieved from south-western Puerto Rico Evaluation of liquefaction potential involved a comprehensive set of isotropically consolidated undrained cyclic triaxial tests on reconstituted samples deformacion axial this calcareous sand.


The programme also included tests on Ottawa terrigenous silica deformacion axial samples prepared and tested in similar conditions for comparison purposes. In general, the experimental results showed that Cabo Rojo calcareous sands had higher liquefaction resistance compared to Ottawa silica sands tested under similar conditions.

Important differences between calcareous and silica sands regarding pore pressure generation characteristics and deformacion axial strain accumulation were also observed Keywords: The significance of damage which can be caused by liquefaction has been recognised for many years e.

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Besides providing valuable background information for readers new to the subject, the material also deformacion axial that the empirical methods used in practice are mostly based on liquefaction case histories involving silicate-based terrigenous sandy soil deposits i e transported from land containing mineral grains such as quartz and feldspar.

There is thus an important gap in current knowledge as few or no liquefaction case histories involving marine biogenous calcareous sands uncemented or cemented have been included in current liquefaction case history databases e. This paper is focused on calcareous biogenous marine sands, deformacion axial hopes to motivate research on non-silica sand liquefaction and to assess the influence of factors such as origin, genesis, deposition history, and mineralogy It presents a summary of results from an experimental research programme aimed at studying the liquefaction resistance of calcareous sands retrieved from surficial beach deposits at Cabo Rojo, south-western Puerto Rico.

The experimental programme involved mineralogical and grain characterisation, critical state line Deformacion axial evaluation, and 31 undrained cyclic triaxial tests on isotropically-consolidated reconstituted samples of uncemented calcareous sands.

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The triaxial samples were tested at three relative densities and three isotropic consolidation stress levels. The experimental programme included similar tests carried out on Ottawa terrigenous silica sand samples for comparison purposes; these were prepared using similar techniques and tested under the same experimental conditions Background SPT-based simplified liquefaction evaluation methodology This section provides background on how liquefaction potential of sandy deposits is commonly assessed in practice.

The methodology presented was based on an extensive database of case histories of sites where evidence of cyclic liquefaction has been reported following a major earthquake. For the SPT-based methodology, these interpreted cyclic stresses levels were compared to deformacion axial SPT blow counts Figure 1 deformacion axial a typical graph summarising empirical data from the SPT-based liquefaction case history database.

This plot shows normalised cyclic stresses presented as cyclic stress ratio - CSR compared to corresponding normalised SPT blow counts N The solid circles represent points where cyclic liquefaction occurred and the open circles the data deformacion axial where no liquefaction was observed.

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The solid black line represents an empirically based line that can be used to estimate the cyclic stresses that would trigger cyclic liquefaction for a certain SPT blow count Several versions of this curve have been presented over the years, changing as the SPT-based cyclic liquefaction database gains additional case histories Versions of this line also differ based on differences in case history interpretations.

Existing procedures for estimating liquefaction potential are currently based on empirical data gathered from sites primarily involving silica sandy soils; a review of the relevant liquefaction literature did not reveal a specific procedure for sandy soil having other mineralogy types or origins such deformacion axial the calcareous sands investigated in this article The definition of liquefaction used in this study As mentioned earlier, soil liquefaction is a complex phenomenon, involving different deformacion axial responses depending on the material stress-strain behaviour, type of loading, initial stress, etc For the purposes of this paper, liquefaction refers to "cyclic liquefaction" involving cyclic softening of the soil due to cyclic loading e.

Marine biogenous sediments and calcareous sands Marine biogenous sediments may be siliceous or calcareous and are formed from planktonic organisms, the most abundant organisms in the ocean Phytoplankton having plant-like photosynthesis and zooplankton grazing like animals are the two main types of plankton.


The insoluble shells of these creatures can be formed of calcite or silica Calcareous biogenous sediments the focus of this deformacion axial consist of large accumulations of the skeletal remains of plants and animal life Skeletal grains are formed as internal or external skeletal units deformacion axial marine organisms, including crustose and articulate corallines, mollusc shells, forams, gastropods, algae, and echinoid fragments.

Methodology The experimental programme used in this study primarily involved sand mineralogical and grain characterisation, characterising the CSL and consolidated undrained cyclic triaxial testing of specimens prepared using Cabo Rojo calcareous sands and Ottawa silica sands.

Thirty-nine consolidated undrained cyclic triaxial tests were performed: This sand was uncemented and classified deformacion axial being white to yellow, fine- to medium-grained, poorly-graded, having sub-angular to angular grains and high internal porosity Figure 2 shows grain characteristics for this sand.