Markéta Lednická

Foundation conditions of buildings in undermined areas: An example of evaluation

Evaluation of a set of individual geological and petrophysical parameters is necessary in many geoscientific studies or those with constructional purposes. However, correlation and mutual evaluation of these parameters are very complicated. Our methodology, which is part of the expert evaluation, is based on compilation of four significant effects: local subsurface geology, groundwater table (and accumulation of surface water), deformation of the surface due to mining (subsidence), and landslides. Different values of specified significances were assigned to all four selected effects. The class of foundation conditions was selected according to the summary of values of specified significances for a given point. This value describes how the selected parameters influence vibration effect on the surface and resistance of buildings to this seismic loading. The pilot map of foundation conditions, which was elaborated as part of the evaluation of Stonava area in 2008, is presented.

Investigation of the Medieval Jeroným Mine Stability: Present Results from a Distributed Measurement Network

Jeroným is a sixteenth century mine situated in western Bohemia near Marianske Lazně. It is being prepared to be the base of a museum of medieval ore mining. As a source of information for investigation of stability of aged mining openings, a distributed measurement network (DMN) combined with seismic station has been built up gradually since 2004. DMN is equipped with sensors for measurement of mine water level changes (3 selected monitoring points), mine temperatures (2 points), rock massif joint aperture changes (4 points), cross-section convergence changes (2 points) and changes of rock massif stress tensor (2 points). Data acquisition unit of DMN is integrated into the seismic recording station that is equipped with data transmission via GSM network. Installation of all above mentioned sensors was finished in May 2009. A brief description of DMN and present results derived from the data obtained are described in the contribution. Monitoring of height changes of high inaccessible ceiling using laser distance meter and changes of stress tensor of rock massif are described in detail.

Coherence spectra of rotational and translational components of mining induced seismic events

Classical Russian S-5-S pendulum seismometer was modified for recording of the rotational components of ground motion. This seismometer was used for monitoring of mining induced seismic events in the Karviná region (Czech Republic). Together, three translational components of ground vibration velocity and one rotational component of ground vibration velocity around the vertical axis were recorded. Elaborated mining induced seismic events with epicentral distances up to 9 km were recorded in Doubrava locality, where the exploitation of black coal is still active. Numerical study of measured component attributes of mining induced seismic events is presented in this paper, namely squared Morlet wavelet coefficients and squared coherence spectrum between rotational and translational components. Squared Morlet wavelet coefficients enable to analyse time-and-frequency structure of elaborated signal, e.g. dynamics of the onset, evolution and disappearance of typical periods of the harmonic peaks, etc. Spectral measure of coherence was applied here for investigation of synchronization effects in 2-dimensional time series of translational and rotational components.

Influence of local geological pattern on values of vibrations induced by road traffic

Buildings in the proximity of roads can be affected by vibrations induced by traffic. Local geological pattern is necessary to be taken into account because it has significant influence on values of vibrations and their characteristics. This paper summarizes results of experimental measurements. Four different types of buildings in different types of local geology were used for this purpose. The obtained results document that the generation of significant vibrations is mostly due to heavy vehicles. Some maximum velocity values exceed acceptable limits according to the Czech Technical Standard 73 0040 for evaluation of technical seismicity effect on buildings. Cosmetic damage, meaning the cracking of plaster, might occur due to traffic vibrations.

Vibration Effect of Near Earthquakes at Different Depths in a Shallow Medieval Mine

The shallow medieval Jeroným Mine is located at a distance of about 25 km southeast of the Nový Kostel focal zone where the most intensive seismic activity in West Bohemia (Czech Republic) has been documented. Permanent seismological monitoring has been carried out since 2004 in this mine. During the 2011 and 2014 seismic swarms, more than 1000 triggered records comprising almost 1500 earthquakes were recorded at the permanent station in the mine. Three short-term seismological experiments were accomplished during these swarms. Several temporary seismic stations were simultaneously placed in different parts of underground spaces which enabled comparison of vibration effect caused by near earthquakes in different parts of the mine. Although the depth of the lowest parts of mine is only about 60 m, a vibration effect generated by earthquakes from the Nový Kostel focal zone is not the same for the whole underground complex.

Analysis of Technical Seismicity in the Vicinity of Reconstructed Road

Analysis of Technical Seismicity in the Vicinity of Reconstructed Road This contribution deals with evaluation of seismic loading of structures located in the vicinity of reconstructed road where vibratory roller was used. Experimental seismological measurements were carried out in Karlova Studánka, Bruntál district. The structures in the vicinity of the reconstructed road are mostly listed and owned by local company - Státní léčebné lázně Karlova Studánka, s.p. In addition to the results of experimental measurement, the contribution also contains results of mathematical modeling. Executed analysis of data demonstrates that the vibration effect on the structures is positively influenced by use of suitable vibration technology. Hodnocení Technické Seizmicity v Okolí Rekonstruované Komunikace Příspěvek se zabývá hodnocením seizmického zatížení stavebních objektů v okolí rekonstruované komunikace při použití těžké vibrační techniky. Konkrétní řešený příklad vychází z experimentálního měření vibrací vyvolaných při rekonstrukci komunikace v obci Karlova Studánka na Bruntálsku. Většina stavebních objektů situovaných v bezprostřední blízkosti komunikace je ve vlastnictví podniku Státní léčebné lázně Karlova Studánka, s.p. a jedná se o památkově chráněné objekty. Kromě výsledků experimentálního měření in situ jsou v příspěvku představeny také výsledky numerického modelování dané situace. Analýza dat prokázala, že použitím vhodné vibrační technologie lze dosáhnout příznivých výsledků z pohledu vlivu na objekty.

Seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel

Abstract This paper deals with the seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel in the Czech Republic. The basic source of data for historical earthquakes up to 1990 was the seismic website [10]. The most intense earthquake described occurred on September 15, 1590 in the Niederroesterreich region (Austria) in the historical period; its reported intensity is Io = 8-9. The source of the contemporary seismic data for the period since 1991 to the end of 2014 was the website [11]. It may be stated based on the databases and literature review that in the period from 1900, no earthquake exceeding magnitude 5.1 originated in the territory of the Czech Republic. In order to evaluate seismicity and to assess the impact of seismic effects at depths of hypothetical deep geological repository for the next time period, the neo-deterministic method was selected as an extension of the probabilistic method. Each one out of the seven survey areas were assessed by the neo-deterministic evaluation of the seismic wave-field excited by selected individual events and determining the maximum loading. Results of seismological databases studies and neo-deterministic analysis of Čihadlo locality are presented.

Study of Site Effect at Seismic Station Located in Undermined Area of Karviná Region (Czech Republic)

The Karviná region is well known as an area with an intensive mining induced seismicity. The local geological pattern, especially subsurface sedimentary layers, belongs to one of the most important factors that influence the amplification of seismic effect on the surface. In order to investigate the amplification effect, there are used methods of spectral ratio that enable to analyse records of vibrations. In the present study, two methods, signed as SSR (standard spectral ratio) and HVSR (horizontal to vertical spectral ratio), were used for the site effect evaluation. The analysis was performed in the populated Doubrava locality where high seismic loading on the surface due to mining induced seismicity is documented.

Long-term Geomechanical Observation in the Jeroným Mine

Geomechanical measurements have been carried out in the medieval Jeroným Mine since 2001. At first quarterly observation and later also continual monitoring by distributed measurement network were used. The network includes a number of different sensors that have been installed in selected places of underground spaces. There have not been any manifestations documenting dangerous changes of stability during the period of monitoring (2001–2015). The results of accomplished measurements from all convergence profiles confirm the total stability of all underground spaces. However, a number of places have been documented as potentially unstable. Measured values of selected parameters are presented in the paper, namely, movements along fractures, changes of stress tensor and fluctuations in the level of mine water table.