Dynamic Soil Parameters Research Articles

Estimation of the soil parameters in Balçova region using multiple geophysical approach

This study aimed to reveal the soil properties in the research area by using various geophysical methods. Physical parameters determining soil characteristics give us a chance to approach how the soil behaves during an earthquake. Thus, precautions can be taken to minimize earthquake damage. Also, safe construction against earthquake effects is important. The studied area is a tectonically and geothermally active area. Izmir Fault zone is passing through the investigation area and trending E–W direction. To investigate soil parameters at this active tectonic region, microtremor method data were recorded and the multichannel analysis of surface waves (MASW) method at 27 profiles was implemented in the study area. Additionally, these methods were supported by the spatial auto correlation (SPAC) method in center spot. Shear wave velocities up to 30 m, soil classification according to the National Earthquake Hazards Reduction Program (NEHRP), site amplification, predominant site period, amplification factor, ground vulnerability index, and shear wave velocity changes up to 300 m were obtained by evaluating the data collected from the applied geophysical methods. VS30 values varied between 700 and 1100 m/s in the southernmost part of the study area, corresponding to a C and B type as soil classification. While the predominant period values were taken as the lowest value of 0.2 s, it was observed to increase up to 5.5 s on the alluvial unit in the northern parts of the study area. The ground vulnerability index, which is directly related to the probability of earthquake damage, was found to be quite high in some parts of the study area. In this paper, we propose microzonation maps for the Balcova district, based on the variation of the soil dynamic parameters.

Determination of the damping ratio by multi-channel spectral analysis of seismic downhole data

Soil dynamic parameters such as shear wave velocity and damping ratio are of major interest in earthquake engineering. While the shear wave velocity, directly linked to the shear modulus, can be determined by a number of laboratory and in-situ tests with satisfying accuracy the damping ratio is much more difficult to obtain. Especially the results of in-situ experiments show often large variations. This is in general due to the troublesome determination of precise signal amplitudes whether in time or frequency domain related with these techniques.The paper presented comes back to a relationship between attenuation and velocity dispersion of body waves which replaces the measurement of the amplitude characteristics of seismic signals by a frequency dependent velocity function. The implementation of this method has previously shown to be difficult because of the very small levels of dispersion observed in seismic data. Our approach aims to overcome the problem by applying a multi-channel spectral analysis which is widely used in surface wave testing to calculate a velocity dispersion. Multi-channel measurements have shown to be more tolerant to erroneous phase characteristics of single seismic traces than the more common two station measurements.The velocity dispersion curve is extracted from a phase velocity–frequency spectrum and the damping ratio is calculated by fitting a theoretical dispersion curve to the extracted curve. The method is demonstrated on correlated data of a seismic downhole test performed using a S-wave vibrator source. The obtained results show a reasonable agreement with damping ratios found in the literature for similar soils.

Economical Smart Farming

Cultivating and agribusiness is the premise of human life which gives nourishment, beats, and other crude materials. The significant consideration in horticulture is soil the board for upgrading crop efficiency is on the upkeep and improvement of dynamic soil parameters. The earthbound confinements, populace stresses and the decrease of customary soil the executives strategies have coordinated to disintegration in the richness of the dirt in creating nations like India. The soundness of yield is a significant component in the profoundly beneficial arrangement of present day agribusiness. The Wild system, it is conceivable to lessen defer and improve throughput for end mile availability. The mist figuring arrangement makes a move with lesser deferral and spares data transmission in the system. The economy of a creating nation for the most part relies upon agribusiness and homesteads in rustic regions and applying conventional methodologies isn't adequate. The proposed framework concentrated on executing an effective AI calculation which is only the blend of more than one ML calculation to shape a cross breed arrange in profound learning. Half breed mix of KNN and SVM Model is created. K-closest neighbor is the semi-managed model and it will be increasingly powerful in parameter level characterization. At last the kind of harvest will be shown.

Determination of seismic hazard and soil response of a critical region in Turkey considering far-field and near-field earthquake effect

Evaluation of earthquake impacts in settlements with a high risk of earthquake occurrence is important for the determination of site-specific dynamic soil parameters and earthquake-resistant structural planning. In this study, dynamic soil properties of Karliova (Bingol) city center, located near to the intersection point of the North Anatolian Fault Zone and the East Anatolian Fault Zone and therefore having a high earthquake risk, were investigated by one-dimensional equivalent linear site response analysis. From ground response analyses, peak ground acceleration, predominant site period, 0.2-sec and 1-sec spectral accelerations and soil amplification maps of the study area were obtained for both near-field and far-field earthquake effects. The average acceleration spectrum obtained from analysis, for a near-field earthquake scenario, was found to exceed the design spectra of the Turkish Earthquake Code and Eurocode 8. Yet, the average acceleration spectrum was found to remain below the respective design spectra of the two codes for the far-field earthquake scenario. According to both near- and far-field earthquake scenarios in the study area, the low-rise buildings with low modal vibration durations are expected to be exposed to high spectral acceleration values and high-rise buildings with high modal vibration durations will be exposed to lower spectral accelerations. While high amplification ratios are observed in the north of the study area for the near-distance earthquake scenario, high amplification ratios are observed in the south of the study area for the long-distance earthquake scenario.

The effect of Soil-structure interaction on Multi-Storey building resonance and Dynamic Shear modulus for Pidie Jaya Aceh earthquake

Earthquake resistance building design must be considered as a design standard in the future for Pidie Jaya - Aceh government as 7th December in 2016 earthquake in Pidie Jaya Aceh which destroyed many major and minor infrastructures. Therefore, soil dynamic parameters must be obtained for design purposes in Pidie Jaya reconstruction and rehabilitation in the future. To avoid the structural failure during the earthquake process, the value of structural vibration frequency (f) should not similar to the value of natural soil vibration frequency (fn). This article aims to determine the soil dynamic parameter of soil layers for disaster mitigation purposes. Several existing buildings namely Dayah Mudi Samalanga, Baitul Muttaqin Mosque, Cubo Bridge, Regent Office Building, Local Lawyer Office and around Pidie Jaya fault were chosen for soil sampling locations. Dynamic parameter of Gmax and Vs are the result of this research. Moreover, the fn value was calculated by Kramer method. Comparison of fn values was performed by simple modeling off values based on SNI 1726-2012. The highest value of the void ratio (e) was obtained in Baitul Muttaqin Mosque soil sample which is 1.84. The highest fn value is at Pidie Jaya fault, which is 2.01 Hz and the lowest fn value is at Baitul Muttaqin Mosque, Pidie Jaya, which is 1.301 Hz.

Study on Influence Factors of Site Ground Motion Parameters Coupling Model

The calculation of ground motion parameters involves many factors such as the acceleration time history of bedrock ground motion, the input interface of bedrock, the shear wave velocity of soil layer and the dynamic parameters of soil mass. And each factor has a certain degree of influence on the final calculation results. Therefore, it is necessary to conduct a scientific and effective sensitivity analysis of the factors affecting the ground motion parameters. And it is also necessary to analyze the influence degree of each factor on the result value, so as to give reasonable calculation results of site ground motion parameters. In this paper, starting with the calculation process of ground motion parameters, combined with the calculation input parameters of bedrock spectrum and the influence parameters of site spectrum, the main factors influencing the calculation results of site ground motions parameters are obtained. Aiming at the influence factors of bedrock seismic time history, bedrock input interface, soil shear wave velocity and soil dynamic parameters, the influence degree of different input parameters on the calculation results of site seismic parameters in analyzed. Finally, it is determined that the soil shear wave velocity, the dynamic triaxial parameters of sand layer and the layered thickness of soil are the key factors affecting the ground motion parameters.

An investigation on the evaluation of dynamic soil characteristics of the Elazig City through the 1-D equivalent linear site-response analysis

Consideration of the effects of the site response in the design of civil structures systems is of important to mitigate the damages to a certain extent on structures and the environment. Hence, it is relatively crucial to reliably attain the dynamic soil parameters of an earthquake-prone city/state. In the current study, a comprehensive investigation on the dynamic soil properties of the city of Elazig with very close proximity to the East Anatolian Fault Zone (EAFZ) having a high potential of producing destructive earthquakes is carried out. Performing probabilistic seismic hazard analysis (PSHA), the moment magnitude of the city is determined as Mw = 7.7 according to 10% probability of exceedance in 50 years. Bedrock-level acceleration spectra is developed utilizing different attenuation relationships for the city, and 1-D equivalent linear site response analysis is conducted on an example soil profile of the city through the SHAKE2000 software considering 16 earthquake motions recorded at the bedrock level. Local surface acceleration spectra obtained from the analysis are then compared to the design spectra of the Turkish Seismic Code for Buildings (TSCB) and Eurocode-8 (EC8) in an attempt to identify the difference between the code spectra and local surface spectra. In addition, in situ geotechnical tests of standard penetration and seismic refraction are conducted at different locations of the study area. Incorporating the results from the field tests into the site response analysis, the soil amplification factor, predominant soil period, peak ground acceleration and spectral maps for the period of T = 0.2 and T = 1.0 s are obtained for the study area. The outcomes from the analysis reveals that structures with higher vibration period than T = 1.0 s are subjected to lower spectral acceleration (Sa), whereas higher Sa values can be used for those with a vibration period lower than T = 0.2 s.

Correction to: In situ assessment of soil dynamic parameters for characterizing nonlinear seismic site response using KiK-net vertical array data

We are very sorry to report a mistake in our recent paper (doi.org/10.1007/s10518-018-00539-3), which left one of the authors (Kenneth W. Campbell) in a reference.

A Comparison between Simple Shear and Triaxial Tests for Evaluating the Variations of G and D with Matric Suction

Shear modulus (G) and damping ratio (D) are both well known as principal soil dynamic parameters. In the present study, cyclic triaxial and simple shear tests are performed on Firuzkuh silica sand at various shear strain amplitudes using the developed testing devices and peripherals. It is well-understood that degrading curvature of G with shear strain appears in both triaxial and simple shear results. Nevertheless, mean confining stress has dissimilar effects in each of the two tests that does not provide comparable empirical correlations. It is noticed that the variations of G and D with suction stress in triaxial differs from those in simple shear. On the basis of cyclic simple shear results, the increase in suction pressure from zero to the end of transition zone in SWCC leads to increase in G values. In triaxial method, on the other hand, similar increase occurs only up to the inflection point in SWCC, starts reducing afterwards down to a limit value at residual water content. The damping ratio variations with shear strain are generally ascending despite local drops at the strain order of 0.1%, which has appeared in both triaxial and simple shear results.

In situ assessment of soil dynamic parameters for characterizing nonlinear seismic site response using KiK-net vertical array data

In this study, we utilize acceleration time histories data at eight KiK-net vertical arrays in Japan, recorded between January 2009 to June 2014, to analyze nonlinear seismic site response. Ground motion records provided by seismic vertical arrays allow estimation of in situ soil dynamic parameters. First, the shear modulus is computed from the shear wave velocity using seismic interferometry by deconvolution. Considering each record as an in situ cyclic test under seismic loading, the shear strain is computed as the velocity ratio between two sensors and the shear stress is assumed as a spatial function of accelerations. Using classic hyperbolic regression models, we quantitatively assess the relationships between the in situ soil dynamic parameters and the level of ground motion. We found nonlinearity starts at a quite low level of shear strain of 5 × 10−6–5 × 10−5, and becomes much more significant beyond a relatively high level of strain of 1 × 10−4. The threshold strains from ground motion observations are well consistent with those from previous laboratory tests. Finally, a parametric analysis is presented to discuss the influence of plasticity index on nonlinear soil behavior evaluations. It is concluded that the threshold acceleration of soil nonlinear behavior (generally ranging from 20 to 100 cm/s2) is mainly controlled by the stiffness and plasticity index, and the degree of soil nonlinear behavior is mainly controlled by the stiffness, plasticity index and the level of ground motion.

Interaction of the base and construction under seismic action, with considering various characteristics of soil damping

In this paper, we determine the characteristics of the physical damping of sand and clay soil by the results of special laboratory tests. The transition from parameters obtained directly from the results of triaxial dynamic tests to parameters of mathematical models of soils used in modern software complexes is shown. The solution of several dynamic FEM problems is exemplified by PLAXIS PC taking into account different damping characteristics of the ground base of a multi-storey building with a developed underground part. Recommendations are given for selecting a soil model for dynamic impact and dynamic soil parameters, and an analysis of the solutions obtained.

Dynamic Site Response Characterization Via Bayesian Inference: Analysis of the SGC Station Deposit in Bogota, Colombia

ABSTRACTIn this paper, we propose a Bayesian framework for parameter estimation in seismic site response analyses. The technique relies on acceleration records provided during excitation by vertical (downhole) arrays of accelerometers. The method uses finite elements simulations of site response to estimate the correlations between dynamic soil parameters and resulting response spectra. Actual acceleration records are incorporated into the analysis in order to estimate the optimal set of parameters that produces a close fit to the actual recorded signal. Experiments are performed making use of information retrieved from three earthquake acceleration records at the SGC station deposit in Bogota, Colombia.

Soil Dynamic Parameters Determination by Waves Spectral and Correlation Analysis

Assessment of soil dynamic parameters via wave propagation method utilizing results of theoretical and experimental analysis of elastic or visco–elastic waves. The theory underlying the problem of stress–wave propagation in half space medium is based on the assumption of an application of the impulse–seismic methods (ISM) or the phase velocity method. In this paper is only outlining the basic of the theoretical subject which is necessary for experimental applications. ISM experimental study of ground stress–wave propagation permits the ground to be modelled as a damped, viscoelastic half space. The viscoelastic model of soil simulation using the complex modulus conception, offers a very good approach to the actual soil behavior. The paper also presents the experimental ISM tests procedure in–situ and results obtained by correlation and spectral analysis. As an example, the finite element method (FEM) was in a case study also used for modelling the body and surface wave propagation processes in the ground modelled as an elastic medium.

Systematic Approaches for Signal Processing of Soil Shaking Table Test

Selecting an appropriate methodology in signal processing of shaking table test is of fundamental importance for evaluating the soil dynamic parameters. This paper presents the systematic approaches in selecting an appropriate signal processing method for a soil shaking table test. A soil model of 150 mm in diameter and 100 mm in height was tested on a 1g shaking table. The soil model was instrumented with accelerometers to measure the resultant accelerations under different shaking motions. Under normal data processing practices, the acceleration data was adjusted and numerically integrated to obtain the linear displacement data. However, the accuracy and reliability of the computed displacement data and the adopted adjustment technique often raise arguments. In the present study, the acceleration data was subjected to two baseline correction schemes and one method of digital band-pass filtering. The results from the three signal processing methods were compared with the actual displacement data obtained from a direct measurement using laser displacement sensor. Bandpass filtering method was found to be a more reliable data processing method in this particular study. The use of laser displacement sensor can serve as a useful reference when choosing an appropriate adjustment scheme in data processing.

Seismic fragility and reliability of structures isolated by friction pendulum devices: seismic reliability‐based design (SRBD)

SummaryThe paper deals with the seismic reliability of elastic structural systems equipped with friction pendulum isolators (friction pendulum system). The behavior of these systems is analyzed by employing a two‐degree‐of‐freedom model accounting for the superstructure flexibility, whereas the friction pendulum system device behavior is described by adopting a widespread model that considers the variation of the friction coefficient with the velocity. With reference to medium soil condition, the uncertainty in the seismic inputs is taken into account by considering a set of artificial records, obtained through Monte Carlo simulations within the power spectral density method, with different frequency contents and characteristics depending on the soil dynamic parameters and scaled to increasing intensity levels. The sliding friction coefficient at large velocity is also considered as random variable modeled through a uniform probability density function. Incremental dynamic analyses are developed in order to evaluate the probabilities exceeding different limit states related to both r.c. superstructure and isolation level defining the seismic fragility curves through an extensive parametric study carried out for different structural system properties.Finally, considering the seismic hazard curves related to a site near L'Aquila (Italy), the seismic reliability of the r.c. superstructure systems is evaluated, and seismic reliability‐based design abacuses are derived with the aim to define the radius in plan of the friction pendulum devices in function of the structural properties and reliability level expected. Copyright © 2016 John Wiley & Sons, Ltd.

The influence of dynamic soil parameters on tractive performance of off-road undercarriages

The influence of dynamic soil parameters on tractive performance of off-road undercarriages

Using the Down Sampling Technique and Running Variance Method for Microtremor Data Filtering

The manner of microtremor data collection and filtering operation has a considerable effect on the accuracy of estimation of dynamic soil parameters. In this paper, an artificial sampling frequency reduction technique has been proposed for removing the high-frequency perturbations from microtremor data and also running variance method has been used to improve the automatic detection of data sections infected by local perturbations. The proposed methods have been applied to the data recorded for the city of Meybod in Iran. Experimental results show that the proposed methods are able to estimate the fundamental frequency more accurately compared to other common methods.

Improvement of Microtremor Data Filtering and Processing Methods Used in Determining the Fundamental Frequency of Urban Areas

The manner of microtremor data collection and filtering operation and also the method used for processing have a considerable effect on the accuracy of estimation of dynamic soil parameters. In this paper, running variance method was used to improve the automatic detection of data sections infected by local perturbations. In this method, the microtremor data running variance is computed using a sliding window. Then the obtained signal is used to remove the ranges of data affected by perturbations from the original data. Additionally, to determinate the fundamental frequency of a site, this study has proposed a statistical characteristics-based method. Actually, statistical characteristics, such as the probability density graph and the average and the standard deviation of all the frequencies corresponding to the maximum peaks in the H/V spectra of all data windows, are used to differentiate the real peaks from the false peaks resulting from perturbations. The methods have been applied to the data recorded for the City of Meybod in central Iran. Experimental results show that the applied methods are able to successfully reduce the effects of extensive local perturbations on microtremor data and eventually to estimate the fundamental frequency more accurately compared to other common methods.

Effects of Construction-Induced Stresses on Dynamic Soil Parameters of Bootlegger Cove Clays

This paper presents the influence of construction-induced stress changes on the dynamic soil parameters of Bootlegger Cove Formation (BCF) clays at the site of the Port of Anchorage (POA) expansion project. Results are presented based on numerical simulations of the POA wharf construction and laboratory experimentation where both free-field and postconstruction conditions are reproduced. The postconstruction stability of the foundation clay is considered under both static and dynamic loadings. For the dynamic case, a cyclic triaxial loading equivalent to the contingency-level earthquake (CLE) established for design was used, whereas for the static case, undrained triaxial compression and extension loadings to failure were employed. The results from numerical simulations and laboratory experiments are presented and compared with field measurements and performance data collected during the project construction. The results obtained from specially designed cyclic triaxial probes show the large effects that the construction-induced stresses can have on the dynamic soil parameters and illustrate the importance of adequately considering such effects. Testing protocols and procedures are proposed for quantifying postconstruction soil parameters to better reflect field values and values at small (and otherwise appropriate) strain levels.

Improving dynamic soil parameters and advancing the pile signal matching technique

The pile signal matching technique widely used for estimating vertical resistances of piles during construction is highly influenced by the assumed dynamic soil parameters. Due to the lack of understanding and supporting data, constant soil parameters for the entire pile length have been routinely used. This practice is unrealistic and compromises the signal match quality. Using recently completed field tests, this paper develops empirical equations for dynamic soil parameters in terms of measureable soil properties and proposes an improved signal matching technique, thereby allowing for better match quality.