Influence of seismic senzor setting on measured values

Import 29/09/2010Zadání bakalářské práce bylo zjistit, jaký vliv má ustavení seizmického senzoru na kvalitu odečítaných hodnot. Součástí bylo vypracovat rešerši o historii, principu a využití seizmických senzorů. Hlavní důraz byl kladen na sestavení pokusu k určení vlivu ustavení senzoru. Pokus sestával ze sestrojení nakloněné roviny a generátoru kmitů. Při realizaci pokusu jsem se nejen seznámil se s měřící aparaturou, ale také jsem získal praktické zkušenosti s prováděním měření. Provedl jsem dvě měření a jejich vyhodnocení. Ve vyhodnocení jsem uvedl naměřené hodnoty a zhodnotil také nepředpokládané zdroje chyb ovlivňující výsledky.Main aim of presented bachelor´s thesis was to determine influence of seismic sensor setting on quality of measured values. Integral part of this thesis was elaboration of background research about history, principle and usage of seismic sensors. Main emphasis was localized on methodology and realization of experimental measurements for determination of seismic sensor setting. Design of inclined plane and realization of oscillation generator represent main preliminary works. I learned with measuring seismological apparatus during experiments and I also obtained operative experiences with preparation and realization of seismological measurements. I performed two measurements and their interpretations. I summarized not only measured values from several tests but I also evaluate nonscheduled sources of mistakes, which influenced obtained results.Prezenční224 - Katedra geotechniky a podzemního stavitelstvívýborn

Analysis of technical seismicity records using wavelet transform - packet decomposition

Článek představuje výsledky analýzy digitálních záznamů technické seizmicity. Výsledky jsou ukázány na svislých složkách záznamů vibrací vyvolaných například beraněním piloty nebo hutněním štěrkového podkladu. K analýze je použit paketový rozklad do 16 frekvenčních hladin, který je založen na waveletové transformaci digitálních signálů s využitím ortogonální Daubechiovské mateřské báze SYM 20.Analysis results of digital records of technical seismicity are presented in this paper. These results are shown on vertical components of signals generated e.g. by pile driving or compaction of graveled base. Packet decomposition into 16 frequency ranges is used for analysis; these decompositions are based on wavelet transform of digital signals using orthogonal Daubechies mother base SYM 20

Experimentally measurement and analysis of stress under foundation slab

Understanding of a load redistribution into subsoil below building foundation is an important knowledge for reliable design and its economy too. The article presents the results of a physical model of a foundation slab and its interaction with the subsoil. The interactions were investigated comprehensively by monitoring the developments of stress in the subsoil and foundation slab settlement during its loading. The load acting on the foundation was applied by strutting the hydraulic press against heavy steel frame which was established by the Department of Building Structures, Faculty of Civil Engineering of VSB -TU Ostrava for this purpose. The preparatory phase of the present experiment involved the homogenization of soil during which trio pressure cells in three horizons were gradually fitted. The quality of homogenization was checked on an ongoing basis through field tests: dynamic penetration load test, dynamic plate load test and seismic measurement of foundation slab response. Finally, the homogenized soil was subjected to mechanical analysis to determine the strength and deformation parameters for basic Mohr-Coulomb constitutive model.Web of Science133513512

Ground-borne vibration due to construction works with respect to brownfield areas

Ground-borne vibration caused by mechanized construction works is the most common problem in built-up areas in general. In post-industrial cities, there are many building facilities in the category of brownfields. Parts of these buildings are often technically and culturally valuable buildings with varying degrees of decay. These are very susceptible to vibrations. The revitalization of brownfield areas employs a wide range of works and practices, among which are those that have adverse effects in the form of vibrations and shocks. This paper presents a theoretical study and original results concerning the seismic load on historical and dilapidated buildings in brownfield areas due to the ground-borne vibration caused by mechanized construction works. Original data from seismic measurements are related to the post-industrial Ostrava agglomeration, in the area of one of the biggest successfully revitalized brownfields in Central Europe. All measurements were evaluated in terms of both amplitude and frequency. The results of all measurements were processed in the form of attenuation curves.Web of Science918art. no. 376

THE EFFECT OF SOIL GRAIN SIZE ON THE DEFORMATION PROPERTIES OF REINFORCED GEOCELL LAYERS

The effect of backfill material grading on the behaviour of geocell reinforced layers was experimentally investigated in this study. A series of loading tests were performed on a model with geocell reinforced and unreinforced layers. Five types of crushed aggregates were used as backfill materials in the experiment. The results showed that geocell reinforcement increased the deformation parameters. The rate of increase of the deformation characteristics depended on the backfill material grading

Experimental seismic measurement on the testing construction and the analyze

Konstrukce „stand“, která byla postavena v areálu Fakulty stavební, VŠB-TU Ostrava, má sloužit k realizaci experimentů a měření z různých oblastí stavitelství. Katedra geotechniky a podzemního stavitelství mimo jiné na konstrukci „standu“, konkrétně na železobetonových základových pásech, prováděla experimentální seizmické měření odezvy vibrační desky. Byl sledován útlum vibrací v prvních metrech od základu, získané záznamy byly vyhodnoceny v amplitudové i frekvenční oblasti a bylo provedeno zhodnocení na základě ČSN 73 0040. Součástí příspěvku je také možný návrh přístupu k analýze odezvy konstrukce na účinky vibrací za pomoci 3D matematického modelu vytvořeného programem SCIA Engineer 2011.1.Construction test „stand”, which was built on the premises of the Faculty of Civil Engineering, Technical University of Ostrava, is intended to implement the experiments and measurements from different areas of engineering. Department of Geotechnics and Underground Engineering carried out experimental measurements of seismic response of plate tamper on concrete strip footing of the construction test „stand”. Vibration attenuation was observed in the first meters from foundation constructions, obtained records were analyzed in amplitude and frequency domain and an evaluation based on ČSN 73 0040. Part of this paper is also possible approach to the response analyze of the structure to the effects of vibration using 3D mathematical model created by SCIA Engineer 2011.1

Alternative approaches to vibration measurement due to the blasting operation: A pilot study

As the infrastructure grows, space on the surface in the urban area is diminishing, and the view of the builders is increasingly moving underground. Implementation of underground structures, however, presents a number of problems during construction. One of the primary side effects of tunnel excavation is vibration. These vibrations need to be monitored for potential damage to structures on the surface, and this monitoring is an integral part of any such structure. This paper brings an original pilot comparative study of standard seismic instrumentation with experimentally developed fiber-optic interferometric and acoustic systems for the purpose of monitoring vibration caused by the blasting operation. The results presented show that systems operating on physical principles (other than those previously used) have the potential to be an alternative that will replace the existing costly seismic equipment. The paper presents waveform images and frequency spectra from experimental measurements of the dynamic response of the rock environment, due to blasting operation performed shallowly during the tunnel excavation of a sewer collector. In the time and frequency domain, there is, by comparison, significant agreement both in the character of the waveform images (recording length, blasting operation timing) and in the spectra (bandwidth, dominant maxima).Web of Science1919art. no. 408

Alternative approaches to measurement of ground vibrations due to the vibratory roller: A pilot study

At present, one of the primary tasks of the construction industry is to build transport infrastructure. This concerns both the construction of new bypasses of towns and the repair of existing roads, which are damaged by congestion, especially by freight transport. Whether it is a new building or a reconstruction, it is always very important to choose a suitable method of subsoil treatment. One of the most commonly used methods for soil treatment is currently compaction using vibratory rollers. This method is very effective both in terms of results and due to its low financial demands compared to other methods. Vibration is transmitted to the surrounding rock environment when compacting the subsoil using vibratory rollers. Although the intensity of these vibrations is not as pronounced as in other methods of subsoil treatment, such vibrations can have a significant effect, for example during compaction in urban areas or in an area with the presence of historical objects. Therefore, it is very advisable to monitor the effect of these vibrations on the environment during construction. This paper brings an original experimental comparative study of standard seismic instrumentation with a developed interferometric sensor for the field of monitoring vibrations generated during compaction of subsoil using vibrating rollers. The paper presents time and frequency domain results, as well as attenuation curves, which represent real attenuation of vibrations in a given rock environment. The results presented here show that a system operating on a different physical principle from the one used at present has the potential to replace the existing, very expensive, seismic equipment.Web of Science1924art. no. 542

EXPERIMENTALLY MEASUREMENT AND ANALYSIS OF STRESS UNDER FOUNDATION SLAB

ABSTRACT: Understanding of a load redistribution into subsoil below building foundation is an important knowledge for reliable design and its economy too. The article presents the results of a physical model of a foundation slab and its interaction with the subsoil. The interactions were investigated comprehensively by monitoring the developments of stress in the subsoil and foundation slab settlement during its loading. The load acting on the foundation was applied by strutting the hydraulic press against heavy steel frame which was established by the Department of Building Structures, Faculty of Civil Engineering of VSB -TU Ostrava for this purpose. The preparatory phase of the present experiment involved the homogenization of soil during which trio pressure cells in three horizons were gradually fitted. The quality of homogenization was checked on an ongoing basis through field tests: dynamic penetration load test, dynamic plate load test and seismic measurement of foundation slab response. Finally, the homogenized soil was subjected to mechanical analysis to determine the strength and deformation parameters for basic Mohr-Coulomb constitutive model

Comparative in situ study of dynamic load generated by gravel piles measured by a fiber-optic interferometer

Currently, all the technology used for seismic monitoring is based on sensors in the electrical domain. There are, however, other physical principles that may enable and fully replace existing devices in the future. This paper introduces one of these approaches, namely the field of fiber optics, which has great potential to be fully applied in the field of vibration measurement. The proposed solution uses a Michelson fiber-optic interferometer designed without polarization fading and with an operationally passive demodulation technique using three mutually phase-shifted optical outputs. Standard instrumentation commonly used in the field of seismic monitoring in geotechnical engineering was used as a reference. Comparative measurements were carried out during the implementation of gravel piles, which represents a significant source of vibration. For the correlation of the data obtained, the linear dependence previously verified in laboratory measurements was used. The presented results show that the correlation is also highly favorable (correlation coefficient in excess of 0.9) from the values measured in situ, with an average deviation for the oscillation velocity amplitude of the optical sensor not exceeding 0.0052.Web of Science2215art. no. 557