Os métodos de ondas superficiais com ênfase nas ondas Rayleigh foram utilizados como o núcleo desse trabalho de Doutorado. Inicialmente, as ondas Rayleigh foram modeladas permitindo o estudo de sensibilidade de suas curvas de dispersão sob diferentes configurações de parâmetros físicos representando diversos modelos de camadas, em que pôde ser observado parâmetros com maior e menor sensibilidade e também alguns efeitos provocados por baixas razões de Poisson. Além disso, na fase de inversão dos dados a modelagem das ondas Rayleigh foi utilizada para a construção da função objeto, que agregada ao método de mínimos quadrados, a partir do método de Levenberg-Marquardt, permitiu a implementação de um algoritmo de busca local responsável pela inversão de dados das ondas superficiais. Por se tratar de um procedimento de busca local, o algoritmo de inversão foi complementado por uma etapa de pré-inversão com a geração de um modelo inicial para que o procedimento de inversão fosse mais rápido e eficiente. Visando uma eficiência ainda maior do procedimento de inversão, principalmente em modelos de camadas com inversão de velocidades, foi implementado um algoritmo de pós-inversão baseado em um procedimento de tentativa e erro minimizando os valores relativos da raiz quadrada do erro quadrático médio (REQMr) da inversão dos dados. Mais de 50 modelos de camadas foram utilizados para testar a modelagem, a pré-inversão, inversão e pós-inversão dos dados permitindo o ajuste preciso de parâmetros matemáticos e físicos presentes nos diversos scripts implementados em Matlab. Antes de inverter os dados adquiridos em campo, os mesmos precisaram ser tratados na etapa de processamento de dados, cujo objetivo principal é a extração da curva de dispersão originada devido às ondas superficiais. Para isso, foram implementadas, também em Matlab, três metodologias de processamento com abordagens matemáticas distintas. Essas metodologias foram testadas e avaliadas com dados sintéticos e reais em que foi possível constatar as virtudes e deficiências de cada metodologia estudada, bem como as limitações provocadas pela discretização dos dados de campo. Por último, as etapas de processamento, pré-inversão, inversão e pós-inversão dos dados foram unificadas para formar um programa de tratamento de dados de ondas superficiais (Rayleigh). Ele foi utilizado em dados reais originados pelo estudo de um problema geológico na Bacia de Taubaté em que foi possível mapear os contatos geológicos ao longo dos pontos de aquisição sísmica e compará-los a um modelo inicial existente baseado em observações geomorfológicas da área de estudos, mapa geológico da região e informações geológicas globais e locais dos movimentos tectônicos na região. As informações geofísicas associadas às geológicas permitiram a geração de um perfil analítico da região de estudos com duas interpretações geológicas confirmando a suspeita de neotectônica na região em que os contatos geológicos entre os depósitos Terciários e Quaternários foram identificados e se encaixaram no modelo inicial de hemi-graben com mergulho para Sudeste. / The surface wave methods to Rayleigh waves were used as the center of this Doctoral work. Initially, the Rayleigh waves were modeled, what enabled the study of the sensitivity of dispersion curves about different sets of physical parameters representing several layer models, wherein it could be observed parameters with higher and lower sensitivity and also some effects caused by low Poisson ratios. Moreover, in the data inversion step the Rayleigh modeling was used for the construction of the object function, that aggregate to the least-squares method, by Levenberg-Marquardt, allowed the implementation of a local search algorithm responsible for data inversion of the surface waves. By reason of being a local search procedure, the data inversion algorithm was complemented with a pre-inversion step wherein an initial model was generated so that the inversion procedure was faster and efficient. Seeking a more efficiency of the inversion procedure, mainly to layer models with velocities inversion, it was implemented a post-inversion algorithm based in a trial and error procedure minimizing the values of the relative Root Mean Squared Error (rRMSE) of the data inversion. More than 50 layer models were used to test the data modeling, pre-inversion, inversion and post-inversion allowing the precise fit of the mathematical and physical parameters present in the several scripts implemented in Matlab. Before to invert the field-acquired data, they need to be treated in the data processing step, whose main aim is the extraction of the dispersion curve caused due the surface waves. For this, three processing methodologies with different mathematical approaches were implemented, also in Matlab. These methodologies were tested and evaluated with synthetic and real data and it was possible to find their strengths and weaknesses, as well as the limitations caused by discretization of the field data. Lastly, the data processing, pre-inversion, inversion and post-inversion steps were unified to form a complete data treatment program of surface waves (Rayleigh). It was used to real data originated by study of a geological problem in the Bacia de Taubaté wherein it was possible to map the geologic contacts along of the seismic acquisition points. The results were compared to an existing initial model based in geomorphological observations of the study area, geological map and global and local geologic information of the tectonic movements in the region. The geophysical The surface wave methods to Rayleigh waves were used as the center of this Doctoral work. Initially, the Rayleigh waves were modeled, what enabled the study of the sensitivity of dispersion curves about different sets of physical parameters representing several layer models, wherein it could be observed parameters with higher and lower sensitivity and also some effects caused by low Poisson ratios. Moreover, in the data inversion step the Rayleigh modeling was used for the construction of the object function, that aggregate to the least-squares method, by Levenberg-Marquardt, allowed the implementation of a local search algorithm responsible for data inversion of the surface waves. By reason of being a local search procedure, the data inversion algorithm was complemented with a pre-inversion step wherein an initial model was generated so that the inversion procedure was faster and efficient. Seeking a more efficiency of the inversion procedure, mainly to layer models with velocities inversion, it was implemented a post-inversion algorithm based in a trial and error procedure minimizing the values of the relative Root Mean Squared Error (rRMSE) of the data inversion. More than 50 layer models were used to test the data modeling, pre-inversion, inversion and post-inversion allowing the precise fit of the mathematical and physical parameters present in the several scripts implemented in Matlab. Before to invert the field-acquired data, they need to be treated in the data processing step, whose main aim is the extraction of the dispersion curve caused due the surface waves. For this, three processing methodologies with different mathematical approaches were implemented, also in Matlab. These methodologies were tested and evaluated with synthetic and real data and it was possible to find their strengths and weaknesses, as well as the limitations caused by discretization of the field data. Lastly, the data processing, pre-inversion, inversion and post-inversion steps were unified to form a complete data treatment program of surface waves (Rayleigh). It was used to real data originated by study of a geological problem in the Bacia de Taubaté wherein it was possible to map the geologic contacts along of the seismic acquisition points. The results were compared to an existing initial model based in geomorphological observations of the study area, geological map and global and local geologic information of the tectonic movements in the region. The geophysical information associated with geological information allowed the generation of an analytical profile of the study region with two geological interpretation confirming the suspect of neotectonic movements in the region wherein the geological contacts between the quaternary and tertiary deposits were identified and they agreed with the initial model of a hemi-graben with dip to Southeast.

Este trabalho apresenta a caracterização in situ de propriedades de interesse geotécnico de maciços de resíduos sólidos urbanos (RSU) e o estudo das propriedades de resistência ao cisalhamento de RSU com diferentes idades. Foram realizadas investigações por sondagens e com métodos geofísicos sísmicos no Aterro Sanitário de São Carlos (ASSC) e ensaios de cisalhamento direto de grandes dimensões (50x50 cm2) com amostras de diferentes idades de aterramento coletadas no ASSC, no Lixão Desativado de São Carlos e em Aterro Experimental construído nas proximidades do Lixão. As investigações realizadas no ASSC revelaram que as diferentes fases de operação do maciço (aterro controlado e aterro sanitário) produziram dois estratos com diferentes propriedades geotécnicas. A umidade, as velocidades de propagação de ondas sísmicas e o peso específico in situ dos dois estratos são distintos, sendo sempre menores e menos dispersos no estrato mais raso (operado como aterro sanitário) e maiores e mais dispersos no estrato mais profundo (operado como aterro controlado). Realizaram-se tentativas de determinação do peso específico in situ dos RSU com medição dos volumes escavados por substituição de volume. Notou-se que os furos tendiam a diminuir de diâmetro assim que a composição de sondagem era retirada e que o método adotado para avanço dos furos, com trado helicoidal de haste oca, promovia segregação dos componentes atravessados, realizando uma amostragem parcial dos mesmos. Foram calculados valores médios de peso específico in situ para o maciço investigado (9 a 15 kN/m3) e identificadas as principais limitações da aplicação deste método a aterros sanitários. A aplicação de métodos geofísicos sísmicos foi fundamental para a diferenciação dos dois estratos e permitiu que se calculasse o módulo de cisalhamento máximo (Go) dos resíduos, que variou significativamente de um estrato para outro. Foi possível comparar os resultados obtidos com a aplicação do método crosshole e do método multichannel analysis of surface waves (MASW) no mesmo aterro sanitário. A caracterização das seis amostras utilizadas nos ensaios de cisalhamento direto revelou que, apesar de elas representarem idades distintas de disposição dos resíduos (2 a 25 anos) e condições de aterramento variadas (formas de operação dos depósitos, ambientes de decomposição e condições de confinamento), a maioria delas se encontrava em estágio avançado de degradação (fase metanogênica) e apenas a mais recente (2 anos de aterramento) encontrava-se em estágio um pouco menos avançado de degradação (início da fase metanogênica). Todas elas exibiram curvas tensão-deslocamento semelhantes, sem pico ou valor de máxima resistência bem caracterizados. Os parâmetros de resistência ao cisalhamento foram obtidos a partir de níveis específicos de deslocamento. Avaliou-se a influência da amostragem, dos procedimentos de preparação das amostras e da composição gravimétrica de cada uma delas sobre os valores calculados para coesão e ângulo de atrito. Para deslocamentos de 100 mm o resíduo aterrado há dois anos apresentou coesão de 13,7 kPa e ângulo de atrito de 22º. Os resíduos mais degradados, com idades de disposição entre 5 e 25 anos, apresentaram coesão de 4,4 kPa e ângulo de atrito de 30º. Utilizaram-se tensões normais de 50, 150 e 250 kPa. Realizaram-se ainda ensaios de cisalhamento direto de grandes dimensões em uma das amostras com corpos de prova em duas posições: paralela e perpendicular à direção de compactação. Os resultados confirmaram que os RSU têm comportamento anisotrópico, sendo que os corpos de prova ensaiados com os componentes alinhados preferencialmente na posição vertical (rotacionados) têm comportamento de endurecimento ainda mais pronunciado que aqueles ensaiados com os componentes orientados preferencialmente no plano horizontal. / Field and laboratory tests were combined to characterize some in-place geotechnical properties of the waste body in the São Carlos Sanitary Landfill (SCSL). The investigation was carried out using hollow stem auger soundings and seismic geophysical methods in the field, and large-scale direct shear testing in the laboratory. The field investigation revealed two strata with different geotechnical properties and they could be related to the different operational phases of the landfill (controlled landfill and sanitary landfill). Moisture content, seismic wave velocities and in-place unit weight were systematically lower and less scattered in the upper stratum than in the lower stratum. The upper stratum was operated as a sanitary landfill and the lower stratum was operated as a controlled landfill. The investigations with geophysical seismic methods were essential for identifying the two strata and allowed for the calculation of the Poisson ratio and the small strain shear modulus (Go) of the waste body. The Poisson ratio showed no sensibility to the waste stratigraphy, but Go values were significantly higher in the lower stratum. Moreover, the results of two different geophysical methods, namely crosshole and multichannel analysis of surface waves (MASW), could be compared. An attempt was made to estimate overboring using a volume substitution method by filling the boreholes with gravel. This aimed at incorporating this aspect in the calculations of the MSW in-place unit weight. Nevertheless, the borings tended to cave in as soon as the augers were removed and this prevented the evaluation of the overboring. Moreover, the hollow stem auger tended to segregate the larger components of the waste and to bring only the smaller ones to the surface. Despite all these difficulties, average values for the MSW inplace unit weight were be calculated (9 to 15 kN/m3). In the laboratory, large-scale direct shear tests (500 x 500 mm2) were performed to provide an insight on the shear strength response of municipal solid waste (MSW) of different landfilling ages. The test samples were collected from the SCSL, a dumpsite and an experimental landfill. Their landfilling ages ranged from 2 to 25 years. Physico-chemical characterization of the samples revealed that most of them were subjected to the metanogenesis degradation phase, in spite of their different landfilling ages and burial conditions (operational characteristics of the deposits, decomposition environment and confining pressures). Only the newest one (2 years old sample) was subjected to an earlier stage of degradation. In the direct shear tests, all samples showed similar stress-strain curves, with continuous strain hardening and no identifiable maximum stress, despite the large displacements. The influence of sampling method, sample preparation and sample gravimetric composition on the calculated shear resistance parameters is discussed. For a 100-mm displacement the shear resistance of the less degraded waste (2 years of landfilling) is best characterized by cohesion = 13.7 kPa and friction angle = 22º. The more degraded wastes (5 to 25 years old samples) are best characterized by cohesion = 4.4 kPa and friction angle = 30º. The tests were performed with initial normal stresses of 50, 150 and 250 kPa. Specific large direct shear tests were performed to evaluate anisotropy in the MSW shear response. The test samples had the fibrous materials oriented perpendicular or parallel to the horizontal shear surface. Results confirmed the expected anisotropy by showing a hardening behaviour that was more pronounced when the fibrous materials were oriented perpendicular to the shear plan.

Thesis advisor: John E. Ebel / Thesis advisor: Alan L. Kafka / As the best seismic indicator of shear modulus, shear-wave velocity is an important property in engineering problems in near-surface site characterization. Several surface-wave methods have been developed to obtain the subsurface shear-wave velocity structure. This thesis compared three surface-wave methods, Spectral Analysis of Surface Waves (SASW) (Nazarian et al., 1983), Multichannel Analysis of Surface Waves (MASW) (Park et al., 1999), and Refraction Microtremor (ReMi) (Louie, 2001), to determine which method gives the best estimation of the 1-D shear-wave velocity profile of near-surface soils. We collected seismic data at three sites in the greater Boston area where there are direct measurements of shear-wave velocities for comparison. The three methods were compared in terms of accuracy and precision. Overall, the MASW and the ReMi methods have comparable quality of accuracy, whereas the SASW method is the least accurate method with the highest percentage differences with direct measurements. The MASW method is the most precise method among the three methods with the smallest standard deviations. In general, the MASW method is concluded to be the best surface-wave method in determining the shear-wave velocities of the subsurface structure in the greater Boston area.

Nondestructive testing (NDT) uses different wave propagation modes to evaluate the internal structure of materials, revealing internal damage such as corrosion and fracturing that cannot be detected by traditional methods. Civil infrastructures are considered high priority assets in Ontario and Canada because of their value, high consequence of failure, and the continual influence of aging effects. Unexpected failure of infrastructure not only costs more than planned replacements but also results in increased safety risks. The in-situ condition assessment of civil infrastructure is critical for the successful implementation of maintenance and safety programs. Therefore, reliable nondestructive methods of inspection are required for the implementation of economical and efficient maintenance and asset management programs. Continuing technological developments in data collection, acquisition equipment, and data processing techniques have provided useful applications of nondestructive methods in many engineering fields. Among the many applications, this research study examines three applications of nondestructive testing in civil engineering: (1) condition assessment of construction joints in asphalt pavements, (2) average thickness evaluation of steel pipes, and (3) void and debonding detection in grouted steel tanks. The study on asphalt focuses on the improvement of the coupling system between the transducers and the asphalt surface, and the development of a new data processing technique to reduce user input and increase the reliability of the condition assessment of longitudinal joints. The current wavelet transmission coefficient (WTC) method requires user input, making the automatic data processing difficult. In the WTC method, the coupling between the transducers and the asphalt surface requires the use of epoxy and aluminum plates. This procedure is not practical for testing in-service roads. A new coupling mechanism using polyurethane foam to provide a spring action on the transducers and calibrated weights to generate a compression force was developed and showed good results, reducing the testing time by up to 50%. A new and robust data analysis methodology, called instantaneous transmission coefficient (ITC), is proposed based on measured instantaneous frequencies and damping ratios. The main advantage of the ITC procedure is that it can be performed automatically, reducing user input. A laboratory scale asphalt slab is used to evaluate the new methodology. Results show good agreement between the WTC and ITC measurements for both jointed and joint-free areas. The second study investigates the feasibility of the multichannel analysis of surface waves (MASW) technique for the evaluation of the average wall thickness of steel pipes. Electromagnetic NDT methods, such as the eddy current and the remote field testing, are common tools for thickness measurement of conductive materials. However, these methods give only localized results where measurements are made, making the process time consuming and inaccurate for assessing the full cross-sectional area of the pipe. Lamb waves have been used previously in the evaluation of steel pipes; however, the existing techniques require prior calibration to a theoretical wave mode, and their accuracy decreases with the length of the pipe evaluated due to wave attenuation effects. Preliminary results show the capability of the MASW test for providing reliable thickness information. The measured dispersion curves include information of fundamental modes and the higher modes, providing an improved characterization of the medium. Thicknesses between 3.2 mm and 12.7 mm are tested with an error of less than 2%. The third study explores the detection of voids in a steel tank filled with lightweight grout. A joint analysis of surface waves and Lamb waves is used for void detection and the identification of debonding conditions in a laboratory scale model of a steel tank filled with grout. Different configurations of the MASW method are conducted using an instrumented hammer (large wavelengths, 10 cm < λ < 25 cm) and a 50 kHz piezoelectric transmitter (small wavelengths, 5 cm < λ < 9 cm) as sources. The attenuation coefficient computed from the Fourier spectra of the measured signals indicates that the presence of a void has an effect on the propagation of the wave. The comparison between experimental and theoretical dispersion curves show that mainly Lamb waves are generated during the testing of the steel tank; thus, detecting the debonding conditions between the steel plate and the grout. Lamb modes are used successfully for detecting the presence of a void beneath the steel wall. The laboratory measurements are effective in the detection of the void, showing amplitudes up to 50% higher, likely because the deformation of the wall is attenuated by the grout.

The geophysical technique known as Multichannel Analysis of Surface Waves, or MASW (Park et al., 1999) is a relatively new seismic characterisation method which utilises Rayleigh waves propagation. With MASW, the frequency dependent, planar travelling Rayleigh waves are created by a seismic source and then measured by an array of geophone receivers. The recorded data is used to image characteristics of the subsurface. This thesis explains how MASW was used as a geotechnical investigation tool on windfarms in the lower North Island, New Zealand, to determine the stiffness of the subsurface at each wind turbine site. Shear‐wave velocity (VS) profiles at each site were determined through the processing of the MASW data, which were then used to determine physical properties of the underlying, weathered greywacke. The primary research site, the Te Rere Hau Windfarm in the Tararua Ranges of the North Island, is situated within the Esk Head Belt of Torlesse greywacke (Lee & Begg, 2002). Due to the high level of tectonic activity in the area, along with the high rates of weathering, the greywacke material onsite is highly fractured and weathering grades vary significantly, both vertically and laterally. MASW was performed to characterise the physical properties at each turbine site through the weathering profile. The final dataset included 1‐dimensional MASW shear‐wave evaluations from 100 turbine sites. In addition, Poisson’s ratio and density values were characterised through the weathering profile for the weathered greywacke. During the geotechnical foundation design at the Te Rere Hau Windfarm site, a method of converting shear wave velocity profiles was utilised. MASW surveying was used to determine VS profiles with depth, which were converted to elastic modulus profiles, with the input parameters of Poisson’s ratio and density. This study focuses on refining and improving the current method used for calculating elastic modulus values from shear‐wave velocities, primarily by improving the accuracy of the input parameters used in the calculation. Through the analysis of both geotechnical and geophysical data, the significant influence of overburden pressure, or depth, on the shear wave velocity was identified. Through each of the weathering grades, there was a non‐linear increase in shear wave velocity with depth. This highlights the need for overburden pressure conditions to be considered before assigning characteristic shear wave velocity values to different lithologies. Further to the dataset analysis of geotechnical and geophysical information, a multiple variant non‐linear regression analysis was performed on the three variables of shear wave velocity, depth and weathering grade. This produced a predictive equation for determining shear wave velocity within the Esk Head belt ‘greywacke’ when depth and weathering data are known. If the insitu geological conditions are not comparable to that of the windfarm sites in this study, a set of guidelines have been developed, detailing the most efficient and cost effective method of using MASW surveying to calculate the elastic modulus through the depth profile of an investigation site.

Nondestructive testing (NDT) uses different wave propagation modes to evaluate the internal structure of materials, revealing internal damage such as corrosion and fracturing that cannot be detected by traditional methods. Civil infrastructures are considered high priority assets in Ontario and Canada because of their value, high consequence of failure, and the continual influence of aging effects. Unexpected failure of infrastructure not only costs more than planned replacements but also results in increased safety risks. The in-situ condition assessment of civil infrastructure is critical for the successful implementation of maintenance and safety programs. Therefore, reliable nondestructive methods of inspection are required for the implementation of economical and efficient maintenance and asset management programs. Continuing technological developments in data collection, acquisition equipment, and data processing techniques have provided useful applications of nondestructive methods in many engineering fields. Among the many applications, this research study examines three applications of nondestructive testing in civil engineering: (1) condition assessment of construction joints in asphalt pavements, (2) average thickness evaluation of steel pipes, and (3) void and debonding detection in grouted steel tanks. The study on asphalt focuses on the improvement of the coupling system between the transducers and the asphalt surface, and the development of a new data processing technique to reduce user input and increase the reliability of the condition assessment of longitudinal joints. The current wavelet transmission coefficient (WTC) method requires user input, making the automatic data processing difficult. In the WTC method, the coupling between the transducers and the asphalt surface requires the use of epoxy and aluminum plates. This procedure is not practical for testing in-service roads. A new coupling mechanism using polyurethane foam to provide a spring action on the transducers and calibrated weights to generate a compression force was developed and showed good results, reducing the testing time by up to 50%. A new and robust data analysis methodology, called instantaneous transmission coefficient (ITC), is proposed based on measured instantaneous frequencies and damping ratios. The main advantage of the ITC procedure is that it can be performed automatically, reducing user input. A laboratory scale asphalt slab is used to evaluate the new methodology. Results show good agreement between the WTC and ITC measurements for both jointed and joint-free areas. The second study investigates the feasibility of the multichannel analysis of surface waves (MASW) technique for the evaluation of the average wall thickness of steel pipes. Electromagnetic NDT methods, such as the eddy current and the remote field testing, are common tools for thickness measurement of conductive materials. However, these methods give only localized results where measurements are made, making the process time consuming and inaccurate for assessing the full cross-sectional area of the pipe. Lamb waves have been used previously in the evaluation of steel pipes; however, the existing techniques require prior calibration to a theoretical wave mode, and their accuracy decreases with the length of the pipe evaluated due to wave attenuation effects. Preliminary results show the capability of the MASW test for providing reliable thickness information. The measured dispersion curves include information of fundamental modes and the higher modes, providing an improved characterization of the medium. Thicknesses between 3.2 mm and 12.7 mm are tested with an error of less than 2%. The third study explores the detection of voids in a steel tank filled with lightweight grout. A joint analysis of surface waves and Lamb waves is used for void detection and the identification of debonding conditions in a laboratory scale model of a steel tank filled with grout. Different configurations of the MASW method are conducted using an instrumented hammer (large wavelengths, 10 cm < λ < 25 cm) and a 50 kHz piezoelectric transmitter (small wavelengths, 5 cm < λ < 9 cm) as sources. The attenuation coefficient computed from the Fourier spectra of the measured signals indicates that the presence of a void has an effect on the propagation of the wave. The comparison between experimental and theoretical dispersion curves show that mainly Lamb waves are generated during the testing of the steel tank; thus, detecting the debonding conditions between the steel plate and the grout. Lamb modes are used successfully for detecting the presence of a void beneath the steel wall. The laboratory measurements are effective in the detection of the void, showing amplitudes up to 50% higher, likely because the deformation of the wall is attenuated by the grout.

Der Beitrag befasst sich mit der Anwendbarkeit von zerstörungsfreien Verfahren zur Bestimmung von Bodenparametern im Zuge der Qualitätssicherung, sowie der Überwachung von risikoreichen Untergrundsituationen. Durch eine oberflächenseimische Untersuchung können künstlich hergestellte Verdichtungskontraste in Sand abgebildet werden. Dabei zeigt sich eine Vergleichbarkeit der Ergebnisse mit Eindringwiderständen von Sondierungen. Im Anschluss wird ein Erdfallversuch zum Verständnis unterirdischer Bruchmechanismen behandelt. Dabei werden Einflussparameter aufgezeigt, welche eine Bodengewölbebildung begünstigen und somit einen Verbruch verhindern. Abschließend folgen Schlussfolgerungen bezüglich der autarken Überwachung von Erdfallphänomenen.

The Multichannel Analysis of Surface Waves (MASW) method traditionally uses an array of collinear vertical geophones to measure seismic wave propagation velocity at discrete points along the ground surface. Distributed fiber optic sensors (FOS) measure the average longitudinal strain over discrete lengths (i.e., zones) of a buried fiber optic cable. Such strain measurements can be used to assess ground motion and thus analyzed with the MASW method. To evaluate the feasibility of using FOS strain measurements in the MASW method, field experiments were conducted with both FOS and surface vertical geophones. Synthetic seismograms were also used to compare FOS to vertical and horizontal geophones and investigate the effect of installation depth and sensor type. Through the MASW method, shear wave (Vs) profiles from the FOS showed comparable results to those obtained with the geophones and achieved the same degree of uncertainty from the non-uniqueness of the MASW inversion process.

No description available.

No description available.