Search Results

You are looking at 1 - 4 of 4 items for

  • Author: Anna Borowiec x
Clear All Modify Search
Open access

Anna Borowiec and Krzysztof Maciejewski

Abstract

Liquefaction has always been intensely studied in parts of the world where earthquakes occur. However, the seismic activity is not the only possible cause of this phenomenon. It may in fact be triggered by some human activities, such as constructing and mining or by rail and road transport.

In the paper a road embankment built across a shallow water reservoir is analyzed in terms of susceptibility to liquefaction. Two types of dynamic loadings are considered: first corresponding to an operation of a vibratory roller and second to an earthquake.

In order to evaluate a susceptibility of soil to liquefaction, a factor of safety against triggering of liquefaction is used (FSTriggering). It is defined as a ratio of vertical effective stresses to the shear stresses both varying with time. For the structure considered both stresses are obtained using finite element method program, here Plaxis 2D. The plastic behavior of the cohesionless soils is modeled by means of Hardening Soil (HS) constitutive relationship, implemented in Plaxis software.

As the stress tensor varies with time during dynamic excitation, the FSTriggering has to be calculated for some particular moment of time when liquefaction is most likely to occur. For the purposes of this paper it is named a critical time and established for reference point at which the pore pressures were traced in time. As a result a factor of safety distribution throughout embankment is generated.

For the modeled structure, cyclic point loads (i.e., vibrating roller) present higher risk than earthquake of magnitude 5.4. Explanation why considered structure is less susceptible to earthquake than typical dam could lay in stabilizing and damping influence of water, acting here on both sides of the slope.

Analogical procedure is applied to assess liquefaction susceptibility of the road embankment considered but under earthquake excitation. Only the higher water table is considered as it is the most unfavorable.

Additionally the modified factor of safety is introduced, where the dynamic shear stress component is obtained at a time step when its magnitude is the highest - not necessarily at the same time step when the pore pressure reaches its peak (i.e., critical time). This procedure provides a greater margin of safety as the computed factors of safety are smaller.

Method introduced in the paper presents a clear and easy way to locate liquefied zones and estimate liquefaction susceptibility of the subsoil - not only in the road embankment.

Open access

Anna Borowiec and Michał Stanuszek

Abstract

Computer Aided Engineering (CAE) is commonly used in modern design of the various types of structures. There are two main issues/aspects that should be consider while using CAE in Geotechnics: the basic theory and material model. The paper deals with a problem of choosing the proper constitutive relationships which according to the authors are equally important in obtaining correct and reasonable results. This problem is illustrated by an example of dynamic calculations of fully saturated non-cohesive soils where liquefaction phenomenon is most likely to occur.

Open access

Magdalena Słowik-Borowiec, Ewa Szpyrka, Anna Kurdziel, Magdalena Grzegorzak and Aneta Matyaszek

Abstract

During the 2010-2011 seasons, analyses of 171 samples of fresh fruit from the south-eastern region of Poland were performed. The research program included the determination of 137 (in 2010) to 152 (in 2011) active substances, together with their metabolites and decomposition products. The analytical methods used in the research were gas chromatography (GC/ECD/NPD) and spectrophotometry (to determine residues of dithiocarbamates). The results were compared with Poland’s allowed maximum residue levels (MRLs).

Residues of active plant protection product substances were detected in 85 samples (50%), while 7 (4%) samples had exceeded the MRLs.

Violations of MRLs were mainly concerned with the following group of insecticides: cypermethrin (in black currant), esfenwalerate (in raspberry), and the fungicides: propiconazole, and difenoconazole (in gooseberries).

Open access

Lech Dudarewicz, Anna Krzymińska, Wanda Hawuła, Magdalena Kozłowska, Urszula Laskowska, Agnieszka Gach, Maciej Borowiec, Wojciech Młynarski, Wojciech Ałaszewski and Lucjusz Jakubowski

Abstract

Objective of the study:

At the moment of study design, there was no data available on prevalence of subtelomeric imbalanced rearrangements in fetuses with abnormal phenotype assessed by ultrasound and with normal classical karyotype, consequently this study was initiated to fill in this gap.

Material & Method:

Amniotic fluid samples or chorionic villi from:

137 fetuses with abnormalities in two or more organ systems

96 fetuses with nuchal translucency above 3.5 mm (99th centile),

85 apparently healthy fetuses (control group) were studied by subtelomeric MLPA, using two kits (P036 and P070) in all cases. Confirmation of a rearrangement was obtained by means of fluorescence in situ hybridization (FISH) studies.

Results:

In the group of fetuses with abnormalities in two or more organ systems, one subtelomeric deletion (de novo deletion (del1p36).) was detected, yielding the detection rate of cryptic subtelomeric imbalances in these pregnancies of 0.84%. In the control group and in the group of fetuses with NT measurement above 3.5 mm, no abnormalities were found.

Conclusion:

The low detection rate of subtelomeric rearrangements in the studied group, together with the low robustness of the method (only one sequence per telomere is studied in one experiment) and necessity to confirm the pathological findings with another method, imply low usefulness of the method in the prenatal setting. In the current era, there are genome-wide methods, like CGH-arrays or SNP-array, which are better-suited for prenatal diagnosis, because of higher yields and lack of necessity of confirmation of the pathological results.