- Détails du magazine
- Première publication
- 09 Nov 2012
- Période de publication
- 4 fois par an
- Accès libre
Pages: 3 - 13
This paper is a presentation of landslide monitoring, early warning and remediation methods recommended for the Polish Carpathians. Instrumentation included standard and automatic on-line measurements with the real-time transfer of data to an Internet web server. The research was funded through EU Innovative Economy Programme and also by the SOPO Landslide Counteraction Project. The landslides investigated were characterized by relatively low rates of the displacements. These ranged from a few millimetres to several centimetres per year. Colluviums of clayey flysch deposits were of a soil-rock type with a very high plasticity and moisture content. The instrumentation consisted of 23 standard inclinometers set to depths of 5-21 m. The starting point of monitoring measurements was in January 2006. These were performed every 1-2 months over the period of 8 years. The measurements taken detected displacements from several millimetres to 40 cm set at a depth of 1-17 m. The modern, on-line monitoring and early warning system was installed in May 2010. The system is the first of its kind in Poland and only one of several such real-time systems in the world. The installation was working with the Local Road Authority in Gorlice. It contained three automatic field stations for investigation of landslide parameters to depths of 12-16 m and weather station. In-place tilt transducers and innovative 3D continuous inclinometer systems with sensors located every 0.5 m were used. It has the possibility of measuring a much greater range of movements compared to standard systems. The conventional and real-time data obtained provided a better recognition of the triggering parameters and the control of geohazard stabilizations. The monitoring methods chosen supplemented by numerical modelling could lead to more reliable forecasting of such landslides and could thus provide better control and landslide remediation possibilities also to stabilization works which prevent landslides.
- monitoring systems
- geotechnical engineering landslide investigations
- Accès libre
Assessment of Susceptibility to Liquefaction of Saturated Road Embankment Subjected to Dynamic Loads
Pages: 15 - 22
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.
- liquefaction susceptibility
- soil dynamic
- seismic lads
- vibrations propagation in soil
- Accès libre
Pages: 23 - 27
The paper presents results of laboratory investigation and analysis of crack initiation threshold identification of dolomite samples. First, selected methods for determining crack initiation thresholds are briefly described with special attention paid to four methods: crack volume strain method , change in Poisson’s ratio , lateral strain response method , and dilatancy method . The investigation performed on dolomite samples shows that for the uniaxial and conventional triaxial compression tests, the above mentioned methods give quite similar values, except for the crack volume strain method. Crack initiation threshold determined by this method has a distinctively lower value than that obtained by the other methods. The aim of the present paper was to review and assess these methods for identifying crack initiation threshold based on laboratory tests of dolomite samples.
- onset of crack initiation
- laboratory investigations
- uniaxial and triaxial compression
- Accès libre
Edge Detection on Images of Pseudoimpedance Section Supported by Context and Adaptive Transformation Model Images
Pages: 29 - 36
Most of underground hydrocarbon storage are located in depleted natural gas reservoirs. Seismic survey is the most economical source of detailed subsurface information. The inversion of seismic section for obtaining pseudoacoustic impedance section gives the possibility to extract detailed subsurface information. The seismic wavelet parameters and noise briefly influence the resolution. Low signal parameters, especially long signal duration time and the presence of noise decrease pseudoimpedance resolution. Drawing out from measurement or modelled seismic data approximation of distribution of acoustic pseuoimpedance leads us to visualisation and images useful to stratum homogeneity identification goal. In this paper, the improvement of geologic section image resolution by use of minimum entropy deconvolution method before inversion is applied. The author proposes context and adaptive transformation of images and edge detection methods as a way to increase the effectiveness of correct interpretation of simulated images. In the paper, the edge detection algorithms using Sobel, Prewitt, Robert, Canny operators as well as Laplacian of Gaussian method are emphasised. Wiener filtering of image transformation improving rock section structure interpretation pseudoimpedance matrix on proper acoustic pseudoimpedance value, corresponding to selected geologic stratum. The goal of the study is to develop applications of image transformation tools to inhomogeneity detection in salt deposits.
- underground storage
- acoustic impedance
- data analysis and visualisation
- edge detection algorithms
- rock salt
- inhomogeneity detection
- Accès libre
Pages: 37 - 45
The paper is focused on changes of geomechanical properties with regard to loss of long-term resistance in studies on the influence of salt spray on the structure of selected rocks from Poland. The investigation has shown that the analyzed rock material shows variable susceptibility to this corrosive factor. The most susceptible to ageing by salt mist were Śmiłów sandstones, whose progressive deterioration was observed in subsequent cycles. Analysis of resistance parameters has shown decreased resistance to uniaxial compression exceeding 30% also in the case of the Józefów limestones. Limestones from Raciszyn have revealed high resistance to ageing by salt mist.
- salt mist
- Accès libre
Pages: 47 - 54
The article presents an application of X-ray microtomography for identification of the carbonation zone in concrete material. A concrete specimen subjected earlier to harsh environmental conditions is investigated. The material is firstly checked with the use of chemical corrosion indicators and then is subjected to microstructural analysis performed with the use of X-ray microtomography. Two different settings of scanning parameters are applied implying the image resolutions of approximately 14 μm per 1 pixel and about 7 μm per 1 pixel, respectively. The results obtained are then compared and analyzed. The depth of the carbonation zone is evaluated based on the attenuation curve. The paper highlights also the significance of the corrosion phenomenon in concrete structures. Details of the deterioration mechanisms in concrete are shortly presented.
- carbonation zone
- X-ray microtomography
- Accès libre
Efficiency of the Needle Probe Test for Evaluation of Thermal Conductivity of Composite Materials: Two-Scale Analysis
Pages: 55 - 62
The needle probe test, as a thermal conductivity measurement method, has become very popular in recent years. In the present study, the efficiency of this methodology, for the case of composite materials, is investigated based on the numerical simulations. The material under study is a two-phase composite with periodic microstructure of “matrix-inclusion” type. Two-scale analysis, incorporating micromechanics approach, is performed. First, the effective thermal conductivity of the composite considered is found by the solution of the appropriate boundary value problem stated for the single unit cell. Next, numerical simulations of the needle probe test are carried out. In this case, two different locations of the measuring sensor are considered. It is shown that the “equivalent” conductivity, derived from the probe test, is strongly affected by the location of the sensor. Moreover, comparing the results obtained for different scales, one can notice that the “equivalent” conductivity cannot be interpreted as the effective one for the composites considered. Hence, a crude approximation of the effective property is proposed based on the volume fractions of constituents and the equivalent conductivities derived from different sensor locations.
- thermal conductivity
- periodic microstructure
- Accès libre
DC Resistivity Studies of Shallow Geology in the Vicinity of Vistula River Flood Bank in Czernichów Village (Near Kraków in Poland)
Pages: 63 - 70
DC resistivity methods, soundings and Electrical Resistivity Tomography, were applied to study shallow geology in the place of planned construction of an experimental flood bank. The geoelectrical surveys provided quantitative information about the spatial presence of the various geoelectrical/geological layers: alluvial soils, sands, gravels and clays. ERT allowed maps to be constructed showing subsurface structure. A combination of geoelectrical and geological information resulted in a much better identification of the geological structure.
- DC resistivity methods
- vertical electrical soundings
- Electrical Resistivity Tomography
- shallow geology
- flood bank
- geophysics in civil engineering
- Accès libre
Pages: 71 - 78
Polish standards concerning field investigation with the use of a Weight Sounding Test (WST) probe give interpretation of results for non-cohesive soils only. The lack of such interpretation for cohesive soils excludes this testing equipment from use. This paper presents the results of geotechnical site investigation and laboratory tests performed for Miocene clays in Carpathian Foredeep in the Cracow area. Based on the analysis of the results a correlation was determined between the characteristic values for the WST probe (number of half-turns NWST) and the selected properties of Miocene clays. The article is an attempt to create a complete interpretation of test results obtained for cohesive soil with WST equipment.
- geotechnical engineering
- weight sounding test WST
- geotechnical site characterization
- soil laboratory investigation
- undrained shear strength
- Accès libre
Pages: 79 - 88
Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite.
However, rock as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if rock with unsuitable rock properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the rock deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of rocks and stones in building industry. Only after 1989 the absorption was accepted as merely informational rock property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and rock deterioration, but more or less good experiences with some high porous rocks used in constructions exposed to severe weather conditions and proving a lack of relationship between rock freeze-thaw resistivity and water absorption.
Results of the recent worldwide research suggest that understanding a resistivity of rocks against deterioration is hidden not in the absorption but in the structure of rock pores in relation to thermodynamic properties of pore water and tensile strength of rocks and rock minerals.
Also this article presents some results of research on rock deterioration and pore structure performed on 88 rock samples. The results divide the rocks tested into two groups - group N in which the pore water does not freeze even when the temperature decreases to -20 ºC, and the second group F in which the pore water freezes. It has been found that the rocks from group N contain critical portion of adsorbed water in pores which prevents freezing of the pore water. The presence of adsorbed water enables thermodynamic processes related to osmosis which are dominantly responsible for deterioration of rocks from group N. A high correlation (R = 0.81) between content of adsorbed water and freeze-thaw loss was proved and can be used as durability estimator of rocks from group N. The rock deterioration of group F is caused not only by osmosis, but also by some other processes and influences, such as hydraulic pressure, permeability, grain size, rock and mineral tensile strength, degree of saturation, etc., and the deterioration cannot be predicted yet without the freeze-thaw test. Since the contents of absorbed water and ratio between adsorbed and bulk water (of which the absorbed water consists) is controlled by the porosity and pore structure, it can be concluded that the deterioration of some rocks is strongly related to rock pore structure.
- mechanical weathering
- rock deterioration
- adsorbed water
- adsorbed water freezing
- rock porosity
- freeze-thaw loss
- Accès libre
Pages: 89 - 101
Based on a literature review concerning methane emissions in Poland, it was stated in 2009 that the National Greenhouse Inventory 2007  was published. It was prepared firstly to meet Poland’s obligations resulting from point 3.1 Decision no. 280/2004/WE of the European Parliament and of the Council of 11 February 2004, concerning a mechanism for monitoring community greenhouse gas emissions and for implementing the Kyoto Protocol and secondly, for the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol.
The National Greenhouse Inventory states that there are no detailed data concerning methane emissions in collieries in the Polish mining industry. That is why the methane emission in the methane coal mines of Górnośląskie Zagłębie Węglowe - GZW (Upper Silesian Coal Basin - USCB) in Poland was meticulously studied and evaluated. The applied methodology for estimating methane emission from the GZW coal mining system was used for the four basic sources of its emission. Methane emission during the mining and post-mining process. Such an approach resulted from the IPCC guidelines of 2006 .
Updating the proposed methods (IPCC2006) of estimating the methane emissions of hard coal mines (active and abandoned ones) in Poland, assumes that the methane emission factor (EF) is calculated based on methane coal mine output and actual values of absolute methane content. The result of verifying the method of estimating methane emission during the mining process for Polish coal mines is the equation of methane emission factor EF.
- methane emission
- statistical analysis
- coal mine
- Accès libre
Pages: 104 - 110
The paper presents numerical simulation of hysteretic live load effect in a soil-steel bridge. The effect was originally identified experimentally by Machelski , . The truck was crossing the bridge one way and the other in the full-scale test performed. At the same time, displacements and stress in the shell were measured. The major conclusion from the research was that the measured quantities formed hysteretic loops. A numerical simulation of that effect is addressed in the present work. The analysis was performed using Flac finite difference code. The methodology of solving the mechanical problems implemented in Flac enables us to solve the problem concerning a sequence of load and non-linear mechanical behaviour of the structure. The numerical model incorporates linear elastic constitutive relations for the soil backfill, for the steel shell and the sheet piles, being a flexible substructure for the shell. Contact zone between the shell and the soil backfill is assumed to reflect elastic-plastic constitutive model. Maximum shear stress in contact zone is limited by the Coulomb condition. The plastic flow rule is described by dilation angle ψ = 0. The obtained results of numerical analysis are in fair agreement with the experimental evidence. The primary finding from the performed simulation is that the slip in the interface can be considered an explanation of the hysteresis occurrence in the charts of displacement and stress in the shell.
- soil-steel structure
- flexible steel culvert
- live load effect
- Accès libre
Pages: 111 - 119
During the construction of an airport terminal it was found that as a result of the hydrostatic pressure of underground water the foundation plate of the building had dangerously shifted in the direction opposite to that of the gravitational forces. The only effective measure was to introduce a drainage system on the site. The complex geology of the area indicated that two independent drainage systems, i.e., a horizontal system in the Quaternary beds and a vertical system in the Tertiary water-bearing levels, were necessary. This paper presents numerical FEM calculations of the two drainage systems being part of the airport terminal drainaged esign. The computer simulation which was carried out took into consideration the actual effect of the drainage systems and their impact on the depression cone being formed in the two aquifers.
- numerical modeling
- drainage system
- depression cone