scholarly journals Behavior of unsaturated pelitic soil in a railway context

2020 ◽  
Vol 195 ◽  
pp. 01010
Author(s):  
Bilal Yoka Khail ◽  
Mathilde Morvan ◽  
Pierre Breul
Keyword(s):  
Cyclic Loading ◽  
In Situ Tests ◽  
Railway Line ◽  
Subgrade Soil ◽  
In Situ Investigation ◽  
Rehabilitation Work ◽  
Hydric Stress ◽  
Soil Water Characteristic Curves

As part of the rehabilitation work on the Gabonese railway line, the Trans-Gabon Railway, it was necessary to analyse the behaviour of the materials constituting the subgrade soil. These soils are pelitic soils whose behaviour under unsaturated conditions and cyclic loading has not been studied before and which present differential settlements and lack of bearing capacity. In this article, we focus on the characterization of the subgrade soil. The objective of this work is first to determine the in-situ characteristics of the pelitic soil and be able to link these characteristics with the behaviour studied in laboratory. For that purpose, we propose an in-situ investigation based on the use of light dynamic penetrometric tests in order to assess the variability of the subgrade layer and a drying-wetting test to assess the influence of hydric stress on the drainage path of the studied soil. We present the results of in-situ tests performed on a study area. We also present the results of the tests to determine the soil water characteristic curves (SWCC) and the curves describing the volumetric behaviour of this soil when exposed to drying.

scholarly journals Experimental Evaluation of Shear Behavior of Stone Masonry Wall

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2313
Author(s):  
Maria Luisa Beconcini ◽  
Pietro Croce ◽  
Paolo Formichi ◽  
Filippo Landi ◽  
Benedetta Puccini
Keyword(s):  
Shear Behavior ◽  
Stone Masonry ◽  
Masonry Walls ◽  
Mechanical Parameters ◽  
In Situ Tests ◽  
Capacity Curves ◽  
Historical Structures ◽  
Definition Of

The evaluation of the shear behavior of masonry walls is a first fundamental step for the assessment of existing masonry structures in seismic zones. However, due to the complexity of modelling experimental behavior and the wide variety of masonry types characterizing historical structures, the definition of masonry’s mechanical behavior is still a critical issue. Since the possibility to perform in situ tests is very limited and often conflicting with the needs of preservation, the characterization of shear masonry behavior is generally based on reference values of mechanical properties provided in modern structural codes for recurrent masonry categories. In the paper, a combined test procedure for the experimental characterization of masonry mechanical parameters and the assessment of the shear behavior of masonry walls is presented together with the experimental results obtained on three stone masonry walls. The procedure consists of a combination of three different in situ tests to be performed on the investigated wall. First, a single flat jack test is executed to derive the normal compressive stress acting on the wall. Then a double flat jack test is carried out to estimate the elastic modulus. Finally, the proposed shear test is performed to derive the capacity curve and to estimate the shear modulus and the shear strength. The first results obtained in the experimental campaign carried out by the authors confirm the capability of the proposed methodology to assess the masonry mechanical parameters, reducing the uncertainty affecting the definition of capacity curves of walls and consequently the evaluation of seismic vulnerability of the investigated buildings.

The Leaching Behaviour of the Swedish KBS-Glasses ABS 39 and ABS 41

1981 ◽  
Vol 6 ◽  
Author(s):  
Hans-Peter Hermansson ◽  
Hilbert Christensen ◽  
Lars Werme ◽  
Kaija Ollila ◽  
Rune Lundqwist
Keyword(s):  
Test Procedure ◽  
Short Description ◽  
Corrosion Products ◽  
In Situ Tests ◽  
Glass Corrosion ◽  
Simulated Waste ◽  
Leaching Behaviour ◽  
Corrosion Investigation

ABSTRACTThe planned Swedish KBS glass corrosion investigation program comprises experiments with inactive glasses containing simulated waste, prolonged in-situ tests, the characterization of corrosion products, immiscibility studies, and corrosion experiments with “hot” glass.This presentation gives a short description of the entire program. It focuses thereafter on some recent leaching results with the inactive KBS glass qualities ABS 39 and ABS 41, which were leached in a manner similar to the PNL MCC–1 test procedure.

scholarly journals Undrained Cyclic Laboratory Behavior of Sandy Soils

Geosciences ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 512 ◽  
Author(s):  
Francesco Castelli ◽  
Antonio Cavallaro ◽  
Salvatore Grasso ◽  
Valentina Lentini
Keyword(s):  
Cyclic Loading ◽  
Seismic Retrofitting ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Residual Performance ◽  
Definition Of

The complex cyclic shear stress path experienced by the soil during an earthquake, which could also induce liquefaction phenomena, can be approximated in the laboratory only by using sophisticated testing apparatuses. Cyclic triaxial tests have been widely used, especially for coarse grained soils, as in this study. In the framework of the design for the seismic retrofitting of the ‘‘Ritiro viaduct’’ foundations along the A20 motorway connecting Messina with Palermo (Italy), a soil liquefaction study was also carried out. With this aim, a detailed geological and geotechnical characterization of the area was performed by in situ and laboratory tests, including seismic dilatometer Marchetti tests (SDMTs), the combined resonant column (RCT) and cyclic loading torsional shear tests (CLTSTs), and undrained cyclic loading triaxial tests (CLTxTs). In particular, the paper presents the results of cyclic triaxial tests carried out on isotropically consolidated specimens of a sandy soil. The seismic retrofitting works include the reinforcement of the foundation and replacement of the decks with newly designed type and structural schemes, mixed steel, and concrete with continuous girder. During the investigation, data were acquired for the characterization of materials, for the definition of degradation phenomena with the relative identification of possible causes, and for the estimation of the residual performance characteristics of the building. The structural campaign of investigations necessary to determine all of the key parameters useful for a correct definition of the residual performance capabilities of the work was divided into two phases: One in situ and one in the laboratory.

In-Situ Mechanical Characterization of a Freestanding 100 Nanometer Thick Aluminum Film in SEM Using MEMS Sensors

2001 ◽  
Vol 695 ◽  
Author(s):  
Aman Haque ◽  
Taher Saif
Keyword(s):  
Mechanical Characterization ◽  
Uniaxial Stress ◽  
Aluminum Film ◽  
Strain Response ◽  
In Situ Tests ◽  
Dislocation Mechanism ◽  
Size Scale ◽  
Displacement Sensors

ABSTRACTWe present the uniaxial stress-strain response of a freestanding 100 nanometer thick 99.99% pure sputtered Aluminum film with grain size about 60 nanometers, tested in-situ inside a SEM chamber. The specimen is cofabricated with MEMS force and displacement sensors to minimize the experimental setup size, allowing both quantitative and in-situ tests to be performed in SEM and TEM chambers. The experimental results strongly suggest that at this size scale, a) Elastic modulus remains same as the bulk Aluminum, b) Yielding starts at about 625 MPa, and c) Strain hardening effect is absent, which indirectly suggests the deformation at this size scale is not dislocation mechanism based.

scholarly journals Shades of blue: non-invasive spectroscopic investigations of Maya blue pigments. From laboratory mock-ups to Mesoamerican codices

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Chiara Grazia ◽  
David Buti ◽  
Anna Amat ◽  
Francesca Rosi ◽  
Aldo Romani ◽  
...  
Keyword(s):  
Reflection Spectroscopy ◽  
Non Invasive ◽  
Artistic Production ◽  
Vibrational Study ◽  
In Situ Investigation ◽  
Maya Blue ◽  
Ft Ir ◽  
Compositional Variability

AbstractMaya blue is a hybrid pigment where an organic component, indigo, is incorporated in a porous clay. Despite its widespread use in the Mesoamerican artistic production and numerous studies devoted to understand the type of interactions between indigo and the host framework, its technology has not been completely unravelled yet. In this study portable non-invasive UV–vis reflection spectroscopy is proposed as a robust method for in situ investigation of Maya blue pigments. Laboratory mock-ups of powder Maya blue have been prepared employing different synthesis procedures (varying the nature of: clays, indigo–clay ratios, heating temperatures and time). The goodness of the prepared Maya blue samples—namely the occurrence of indigo–clay interactions—have been probed by micro-Raman spectroscopy and related UV–vis spectral markers have been identified. DFT calculations as well have been performed to deeply explain UV–vis profiles. The set of spectral markers have been finally exploited to interpret spectra recorded on Mesoamerican pictorial codices, through a multi-technique approach based on exploring the UV–Vis properties of the blue paint supported by the FT-IR vibrational study of the inorganic clays. The characterization of blue colours on pre-Hispanic and colonial Mesoamerican codices contribute to a better understanding of the compositional variability of these painting materials and to point out the existence of different technological traditions of colour preparation in ancient Mesoamerica.

scholarly journals Structural Characteristics Analysis of Overlying Rocks and Prevention Measures with a Long-Wall Face Passing Across Abandoned Roadways: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zeng-Qiang Yang ◽  
Chang Liu ◽  
Guo-An Wang ◽  
Gang-Wei Li ◽  
Feng-Shuo Li
Keyword(s):  
Physical Simulation ◽  
Structural Characteristics ◽  
Coal Pillar ◽  
Main Roof ◽  
Prevention Measures ◽  
Monitoring Methods ◽  
In Situ Tests ◽  
In Situ Investigation ◽  
Occurrence Mechanism

In order to study the occurrence mechanism of advanced coal pillar instability failure and support crushing accidents during a long-wall face passing across abandoned roadways period, the Panel LW3101 in Shenghua Colliery was taken as a typical engineering background. By means of in situ investigation, physical simulation experiment, theoretical analysis, in situ tests, and relevant monitoring methods, the occurrence mechanism and prevention measures are studied. The results show that the bearing stress in advanced coal pillar is accumulated larger and larger with the width of advanced coal pillar gradually decreasing, and meanwhile, the key stratum in overlying strata would also be sliding instability under some minimum critical width condition; the sudden failure of advanced coal pillar which leads to a sharp increase of bending moment is the key factor that induces fracture of the main roof in front of long-wall face, and the advanced fracture of the main roof can be prevented by changing the stress state of the advanced coal pillar from a two-dimensional state to a three-dimensional state; the method of backfilling abandoned roadway is used to improve the stability of advanced coal pillar and the corresponding monitoring results verify that this method is effective. The research conclusions provide a theoretical foundation and new guidance for preventing advanced coal pillar instability failure and support crushing accidents under a long-wall face passing across abandoned roadways condition.

Engineering Properties of Soils on Boubyan Island in Kuwait

2013 ◽  
Vol 815 ◽  
pp. 273-278
Author(s):  
Shu Feng Bao ◽  
Jian Hua Huang
Keyword(s):  
Void Ratio ◽  
Saline Soil ◽  
Salt Content ◽  
Soil Classification ◽  
Engineering Properties ◽  
In Situ Tests ◽  
Railway Line ◽  
High Salt Content ◽  
Low Sensitivity

To full understand engineering properties of soils on Boubyan island in Kuwait, some in-situ tests were performed along the highway and railway line, meanwhile some laboratory tests for soil samples from the different depth. It was concluded that its properties was low void ratio, low moisture content, low plasticity, low sensitivity, low permeability and high salt content. The soil classification belonged to CL and Marine-chloride-highly saline-soil.

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