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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of SCPT-surveys as method for accessing dynamic modulus

Granskär, Joakim January 2018 (has links)
The purpose of this master thesis is to evaluate the results from the completed SCPT (Seismic Cone Penetration Test) surveys with respect to the methods ability to estimate dynamic young´s modulus. This has been done by comparing the result from SCPT to other seismic methods and dynamic parameters converted from “static” geotechnical surveys. SCPT is a relatively new method which has not been used by Sweco or in Sweden to any greater extent and is therefore of interest to be looked in to. By adding two geophones to an ordinary CPT (Cone Penetration Test) equipment as well as including strike plates, hammer and logger system one can log dynamic parameters in addition to the regular parameters logged by a CPT system. This is done by stopping the otherwise continuous CPT survey every meter and striking the strike plates, which are placed under the tracks of the drilling rig. Seismic waves will then travel through the soil down to the geophones and be used to calculate dynamic parameters. For this master thesis a total of 47 geotechnical and geophysical surveys have been considered. The location of these 47 are approximately 7 km north of Norrköping and have been conducted between the years 2016-2017 for the East Link Project. The geotechnical surveys are composed of weight-sounding, ram-sounding and CPT while the geophysical ones are SCPT, refraction-survey and MASW (Multichannel Analysis of Surface Waves). Static elastic parameters have been calculated using the geotechnical survey results according to the Swedish transportation administrations standardized methods. These have then been converted to dynamic parameters with the help of different relationships. When these have been converted they can be compared to SCPT results and other seismic survey methods which also use wave velocity, Poisson’s ratio and density to calculate dynamic elastic parameters. Based on the results from this thesis it can be concluded that the seismic test add-on to a standard CPTu survey is a good method for accessing dynamic modules and it gives extended information of the soil stratigraphy from one single survey point. After the studies and analyses conducted for this thesis it can be concluded that the proposed conversion between static and dynamic young’s modulus using the Alpan curve gives slightly higher values than the ones derived directly from shear waves using SCPT. The other conversion using cone tip resistance to shear wave velocity gives on the other hand slightly lower values than the ones measured with the SCPT. The analysis also indicate similar trends in results between the different seismic methods. These results does however also shows that the used assumptions are somewhat general for accurate comparisons between the methods.
2

Desenvolvimento de um sistema para realização de ensaios sísmicos down-hole em conjunto com o CPT / Seismic testing down-hole in conjunction with CPT

Vitali, Osvaldo Paiva Magalhães 25 February 2011 (has links)
Quando ocorrem solicitações dinâmicas nos solos, torna-se indispensável a determinação do módulo de cisalhamento máximo (Go) para elaboração de projetos de Engenharia Geotécnica. Este parâmetro pode ser determinado a partir da velocidade de propagação das ondas S (Vs). Em campo, os ensaios mais empregadas para determinação de Vs são o cross-hole e o down-hole. O down-hole tem sido bastante empregado com a incorporação de geofones em ponteiras de piezocone. Esse ensaio tem se mostrado uma maneira rápida, econômica e muito confiável para determinação de Go, apresentando resultados consistentes com os obtidos no ensaio cross-hole. O objetivo deste trabalho é o desenvolvimento de um sistema para realização do ensaio sísmico down-hole e sua implantação. Inúmeros ensaios foram realizados no campus da Universidade Estadual Paulista, em Bauru/SP a fim de testar os procedimentos para execução do ensaio, os equipamentos utilizados e as técnicas de interpretação, onde se observou que a manutenção do eixo de vibração dos geofones paralelo a direção de aplicação do golpe foi o fator que mais influenciou na qualidade dos sinais. Para analisar a resposta dos geofones instalados na ponteira desenvolvida, realizaram-se ensaios em laboratório, onde se verificou que os geofones apresentavam resposta idêntica ao dos acelerômetro de referência. Por fim, foram realizados ensaios em três campos experimentais no interior do Estado de São Paulo, onde estão disponíveis resultados de ensaios cross-hole e ensaios down-hole realizados com equipamentos comerciais. Os resultados obtidos com o sistema desenvolvido nestes campos permitiram validar o sistema desenvolvido. / In the design stages of geotechnical engineering of a given project, it is imperative to ascertain the maximum shear modulus (Go) of those soils experiencing dynamic loads. One common method to determine Go is to measure shear wave velocity. Most field experiments are the cross-hole and down-hole tests to determine the velocity of shear waves. The downhole test has been widely used in conjunction with geophones placed behind the tip of piezocones. The down-hole test has proven to be a fast, economic, and very reliable method to determine Go, it has produced data consistent with results obtained in cross-hole tests. The objective of this work is to present a comprehensive system for the down-hole test, which includes its implementation, execution, and the interpretation of data collected. Several tests were performed at the campus of Universidade Estadual Paulista, UNESP, in Bauru, S.P. The objective of those experiments was to test the execution procedures and method of interpretation. It was observed the quality of the results obtained was chiefly dependent on maintaining the axis of vibration of the geophones parallel to the direction of application of the original blow. The analysis of the response by the geophones installed at the tip of the cone included experiments performed at the laboratory, where it was observed that the geophones responded identically to those accelerometers used as reference. Further, downhole experiments using system proposed here were performed in three experimental research sites of the state of São Paulo. The objective was to compare results to the data available in literature, which were obtained using commercial SCPT equipment and cross-hole tests. The down-hole testswere performed within the guidelines of the system proposed here and the results of the experiment served to corroborate the suitability of the developed system.
3

Desenvolvimento de um sistema para realização de ensaios sísmicos down-hole em conjunto com o CPT / Seismic testing down-hole in conjunction with CPT

Osvaldo Paiva Magalhães Vitali 25 February 2011 (has links)
Quando ocorrem solicitações dinâmicas nos solos, torna-se indispensável a determinação do módulo de cisalhamento máximo (Go) para elaboração de projetos de Engenharia Geotécnica. Este parâmetro pode ser determinado a partir da velocidade de propagação das ondas S (Vs). Em campo, os ensaios mais empregadas para determinação de Vs são o cross-hole e o down-hole. O down-hole tem sido bastante empregado com a incorporação de geofones em ponteiras de piezocone. Esse ensaio tem se mostrado uma maneira rápida, econômica e muito confiável para determinação de Go, apresentando resultados consistentes com os obtidos no ensaio cross-hole. O objetivo deste trabalho é o desenvolvimento de um sistema para realização do ensaio sísmico down-hole e sua implantação. Inúmeros ensaios foram realizados no campus da Universidade Estadual Paulista, em Bauru/SP a fim de testar os procedimentos para execução do ensaio, os equipamentos utilizados e as técnicas de interpretação, onde se observou que a manutenção do eixo de vibração dos geofones paralelo a direção de aplicação do golpe foi o fator que mais influenciou na qualidade dos sinais. Para analisar a resposta dos geofones instalados na ponteira desenvolvida, realizaram-se ensaios em laboratório, onde se verificou que os geofones apresentavam resposta idêntica ao dos acelerômetro de referência. Por fim, foram realizados ensaios em três campos experimentais no interior do Estado de São Paulo, onde estão disponíveis resultados de ensaios cross-hole e ensaios down-hole realizados com equipamentos comerciais. Os resultados obtidos com o sistema desenvolvido nestes campos permitiram validar o sistema desenvolvido. / In the design stages of geotechnical engineering of a given project, it is imperative to ascertain the maximum shear modulus (Go) of those soils experiencing dynamic loads. One common method to determine Go is to measure shear wave velocity. Most field experiments are the cross-hole and down-hole tests to determine the velocity of shear waves. The downhole test has been widely used in conjunction with geophones placed behind the tip of piezocones. The down-hole test has proven to be a fast, economic, and very reliable method to determine Go, it has produced data consistent with results obtained in cross-hole tests. The objective of this work is to present a comprehensive system for the down-hole test, which includes its implementation, execution, and the interpretation of data collected. Several tests were performed at the campus of Universidade Estadual Paulista, UNESP, in Bauru, S.P. The objective of those experiments was to test the execution procedures and method of interpretation. It was observed the quality of the results obtained was chiefly dependent on maintaining the axis of vibration of the geophones parallel to the direction of application of the original blow. The analysis of the response by the geophones installed at the tip of the cone included experiments performed at the laboratory, where it was observed that the geophones responded identically to those accelerometers used as reference. Further, downhole experiments using system proposed here were performed in three experimental research sites of the state of São Paulo. The objective was to compare results to the data available in literature, which were obtained using commercial SCPT equipment and cross-hole tests. The down-hole testswere performed within the guidelines of the system proposed here and the results of the experiment served to corroborate the suitability of the developed system.
4

Development of the Spectral-Analysis-of-Body-Waves (SABW) method for downhole seismic testing with boreholes or penetrometers

Kim, Changyoung 13 November 2012 (has links)
Downhole seismic testing and seismic cone penetration testing (SCPT) have shown little change since the 1990’s, with essentially the same sensors, sources, test procedures and analytical methods being used. In these tests, the time differences of first-arrivals or other reference points early in the time-domain signals have been used to calculate shear and compression wave velocities in soil and rock layers. This time-domain method requires an operator to pick the first arrival or other reference point of each seismic wave in the time record. Picking these reference points correctly is critical in calculating wave velocities. However, picking these points in time records is time consuming and is not always easy because of low signal-to-noise ratios, especially in the case of shear waves which arrive later in the time record. To avoid picking reference points, a cross-correlation method is sometimes applied to determine travel times of the seismic waves, especially in traditional downhole testing. One benefit of the cross-correlation method is that it can be automated. The cross-correlation method is not, however, appropriate for evaluation other body wave characteristics such as wave dispersion and material damping. An alternate approach is to use frequency-domain analysis methods which are well suited for evaluating time changes between all types of waveforms measured at spatially different points. In addition, frequency-domain methods can be automated and attenuation measurements can also be performed. Examples of such testing procedures with Rayleigh-type surface waves in geotechnical earthquake engineering are the Spectral-Analysis-of-Surface-Waves (SASW) and Multi-Channel-Analysis-of-Surface-Waves (MASW) methods. In this research, an automated procedure for calculating body wave velocities that is based on frequency-domain analysis is presented. The basis for and an automated procedure to calculated body wave dispersion is also presented. Example results showing shear wave velocity and material damping measurements in the SCPT are presented. The objective of this study is to improve downhole seismic tests with boreholes, cone penetrometers or flat-plate dilatometers by developing a frequency-domain analysis method which overcomes many of the disadvantages of time-domain analyses. The frequency-domain method is called the Spectral-Analysis-of-Body-Waves (SABW) method. The SABW method does not require an operator to pick the first-arrival or other reference times. As a result, the shear wave velocities and wave dispersion can be calculated in real time using the interpretation method with an automatic calculation procedure, thus reducing human subjectivity. Also, the SABW method can be used to determine additional information from the dispersion curves such as the material damping ratio and an estimate of soil type based on the dispersion relationship. In this research, field SCPT measurements are presented as an example to illustrate the potential of the SABW method. Measurements with shear waves are highlighted because these measurements are most often required in geotechnical earthquake engineering studies. / text
5

Undersökning av konsolideringens inverkan på skjuvvågshastighet med SCPT i svensk finkornig jord : Med jämförelse mot empiriskt samband

Lindström, Markus, Martin, Oldgren January 2020 (has links)
Att kunna utvärdera dynamiska parametrar i finkornig jord har blivit allt mer aktuellt i Sverige, inte minst på grund av de nya höghastighetsbanorna som ska byggas inom snar framtid. Tågens höga hastigheter kommer skapa dynamiska vågor som breder ut sig i den underliggande jorden. Om vågorna inte är snabbare än tåget själv, kan en dynamisk amplifikation ske vilket kan skapa obehag för passagerarna och stabilitetsproblem i jorden. Risken för dessa problem finns i lösa och finkorniga jordar där våghastigheterna är relativt låga.Syftet med detta examensarbete är att studera vilken inverkan konsolideringen har på skjuvvågshastigheten i finkornig jord samt att undersöka om befintligt empiriskt samband från Trafikverkets tekniska kravdokument (TK Geo) ger tillförlitliga värden på skjuvvågshastigheten. För att besvara detta har Seismic Cone Penetration Test (SCPT) utförts för att mäta skjuvvågshastigheten i finkornig jord under och utanför provbankar. Materialparametrarna som har använts i det empiriska sambandet har erhållits från rutinundersökningar, CRS och CPT-sonderingar.Undersökningen har utförts på SGI;s två provfält med olika finkorniga jordar, det ena i Skå-Edeby och det andra i Lampen. Provfältet i Skå-Edeby har stått i drygt 60 år och nya kolvprover och CPT-sonderingar utfördes för att erhålla aktuella materialparametrar. I Lampen har provfältet stått i knappt tio år men där har inga nya jordprover tagits utan resultat från tidigare utförda undersökningar har legat till grund för de empiriska beräkningarna.Resultatet från undersökningen i Skå-Edeby påvisar tydligt att konsolidering av finkornig jord ökar skjuvvågshastigheten i jorden. I Lampen blev resultatet inte lika tydligt men visar ändå generellt sett högre värden hos skjuvvågshastigheten i den konsoliderade jorden jämfört med jungfrulig jord.Skjuvvågshastigheterna som beräknats med hjälp av det empiriska sambandet verkar ge tillförlitliga resultat där de i Skå-Edeby följer en likartad trend som de uppmätta skjuvvågshastigheterna. För Lampen är däremot trenden inte lika tydlig där de empiriska beräkningarna mestadels gav högre skjuvvågshastigheter än de uppmätta hastigheterna vid de olika nivåerna i jordprofilen. Den bästa överensstämmelsen mellan uppmätt skjuvvågshastighet och empiriskt uppskattad skjuvvågshastighet erhölls dock för den obelastade, jungfruliga jorden vid båda undersökningsplatserna. / The ability to evaluate dynamic parameters in fine grain soil has become more relevant in Sweden, not least because of the new high-speed railways that are planned to be built in the near future. The high speed of the trains will create dynamic waves that will spread into underlying soil. If the velocity of these waves is slower than the train itself, it could create a dynamic amplification which can cause discomfort for passengers and stability problems in the soil. This is a risk in loose and fine grain soils where the wave velocity is relatively low.This work aims to study what impact consolidations have on the shear wave velocity in fine grain soil and also to evaluate if existing empirical relationship from the Swedish transport administration gives reliable results regarding the shear wave velocity. In order to answer this, the method SCPT (Seismic Cone Penetration Test) have been used to measure the shear wave velocity in fine grain soil beneath and next to an embankment. The material parameters that´s been used in the empirical relationship has been obtained from routine investigation, CRS and CPT-probes.Field investigations has been performed at SGI;s two test fields with different kind of fine grain soil, one in Skå-Edeby and the other one in Lampen. The test field in Skå-Edeby has been standing for 60 years and new piston samples and CPT-probes has been performed to obtain current material parameters. In Lampen, the test field has been standing for almost ten years and no new soil samples have been taken. Instead, results from previous performed soil investigations has been used in the empirical calculations.Results from the study in Skå-Edeby clearly show that the consolidation of fine grain soil increases the shear wave velocity in the soil. In Lampen, the results were not as clear but still show generally higher values of the shear wave velocity in the consolidated soil compared to virgin soil.The shear wave velocities calculated using the empirical relation appear to produce reliable results where, in Skå-Edeby, they follow a similar trend as the measured shear wave velocities. For Lampen, however, the trend is not as clear where most of the empirical calculations gave higher velocities than the measured ones at most levels in the soil profile. For both Skå-Edeby and Lampen, the smallest difference between measured and empirical shear wave velocities were obtained in the unloaded, virgin soil.
6

Enhanced Integration of Shear Wave Velocity Profiling in Direct-Push Site Characterization Systems

McGillivray, Alexander Vamie 13 November 2007 (has links)
Enhanced Integration of Shear Wave Velocity Profiling in Direct-Push Site Characterization Systems Alexander V. McGillivray 370 Pages Directed by Dr. Paul W. Mayne Shear wave velocity (VS) is a fundamental property of soils directly related to the shear stiffness at small-strains. Therefore, VS should be a routine measurement made during everyday site characterization. There are several lab and field methods for measuring VS, but the seismic piezocone penetration test (SCPTu) and the seismic dilatometer test (SDMT) are the most efficient means for profiling the small-strain stiffness in addition to evaluating large-strain strength, as well as providing evaluations of the geostratigraphy, stress state, and permeability, all within a single sounding. Although the CPT and DMT have been in use for over three decades in the USA, they are only recently becoming commonplace on small-, medium-, and large-size projects as more organizations begin to realize their benefits. Regrettably, the SCPTu and the SDMT are lagging slightly behind their non-seismic counterparts in popularity, in part because the geophysics component of the tests has not been updated during the 25 years since the tests were envisioned. The VS measurement component is inefficient and not cost effective for routine use. The purpose of this research is to remove the barriers to seismic testing during direct-push site characterization with SCPTu and SDMT. A continuous-push seismic system has been developed to improve the integration of VS measurements with SCPTu and SDMT, allowing VS to be measured during penetration without stopping the progress of the probe. A new type of portable automated seismic source, given the name RotoSeis, was created to generate repeated hammer strikes at regularly spaced time intervals. A true-interval biaxial seismic probe and an automated data acquisition system were also developed to capture the shear waves. By not limiting VS measurement to pauses in penetration during rod breaks, it is possible to make overlapping VS interval measurements. This new method, termed frequent-interval, increases the depth resolution of the VS profile to be more compatible with the depth intervals of the near-continuous non-seismic measurements of the SCPTu and the SDMT.
7

An Engineering Geological Investigation of the Seismic Subsoil Classes in the Central Wellington Commercial Area.

Semmens, Stephen Bradley January 2010 (has links)
The city of Wellington has a high population concentration and lies within a geologically active landscape at the southern end of the North Island, New Zealand. Wellington has a high seismic risk due to its close proximity to several major fault systems, with the active Wellington Fault located in the north-western central city. Varying soil depth and properties in combination with the close proximity of active faults mean that in a large earthquake rupture event, ground shaking amplification is expected to occur in Thorndon, Te Aro and around the waterfront. This thesis focuses on the area bounded by Thorndon Overbridge in the north, Wellington Hospital in the south, Kelburn in the west, and Oriental Bay in the east. It includes many of the major buildings and infrastructural elements located within the central Wellington commercial area. The main objectives were to create an electronic database which allows for convenient access to all available data within the study area, to create a 3D geological model based upon this data, and to define areas of different seismic subsoil class and depth to rock within the study area at a scale that is useful for preliminary geotechnical analysis (1:5,000. Borelogs from 1025 holes with accompanying geological and geotechnical data obtained from GNS Science and Tonkin & Taylor were compiled into a database, together with the results from SPAC microtremor testing at 12 sites undertaken specifically for this study. This thesis discusses relevant background work and defines the local Wellington geology. A 3D geological model of the central Wellington commercial area, along with ten ArcGIS maps including surficial, depth to bedrock, site period, Vs30, ground shaking amplification hazard and site class (NZS 1170.5:2004) maps were created. These outputs show that a significant ground shaking amplification risk is posed on the city, with the waterfront, Te Aro and Thorndon areas most at risk.

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