scholarly journals Empirical relationships of shear wave velocity, SPT-N value and vertical effective stress for different soils in Mashhad, Iran

2015 ◽  
Vol 58 (3) ◽  
Author(s):  
Azam Ghazi ◽  
Naser Hafezi Moghadas ◽  
Hosein Sadeghi ◽  
Mohamad Ghafoori ◽  
Gholam Reza Lashkaripur
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Effective Stress ◽  
Shear Wave Velocity ◽  
Response Analysis ◽  
Empirical Relationships ◽  
Data Set ◽  
Fine Grain ◽  
Geophysical Investigations ◽  
Vertical Effective Stress

<p>Shear wave velocity, V<sub>s</sub>, is one of the important input parameters in seismic response analysis of the ground. Various methods have been examined to measure the soil V<sub>s</sub> directly. Direct measurement of V<sub>s</sub> is time consuming and costly, therefore many researchers have been trying to update empirical relationships between V<sub>s</sub> and other geotechnical properties of soils such as SPT Blow count, SPT-N. In this study the existence of a statistical relationship between V<sub>s</sub>, SPT-N<sub>60 </sub>and vertical effective stress, signa<sub>nu</sub>´, is investigated. Data set we used in this study was gathered from geotechnical and geophysical investigations reports. The data have been extracted from more than 130 numbers of geotechnical boreholes from different parts of Mashhad city. In each borehole the V<sub>s</sub> has been measured by downhole method at two meter intervals. The SPT test also has performed at the same depth. Finally relationships were developed by regression analysis for gravels, sands and fine grain soils. The proposed relationships indicate that V<sub>s</sub> is strongly dependent on signa<sub>nu</sub>´. In this paper the effect of fine percent also is considered on the V<sub>s</sub> estimation.</p>

Topographically-Derived Near-Surface Shear Wave Velocity Map for Pakistan

2017 ◽  
Vol 11 (02) ◽  
pp. 1650010 ◽  
Author(s):  
Saeed Zaman ◽  
Pennung Warnitchai
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Site Response ◽  
Response Analysis ◽  
Site Classification ◽  
Site Conditions ◽  
Data Set ◽  
Near Surface ◽  
Topographic Slope

Shear wave velocity ([Formula: see text]) through the uppermost subsurface (30 m) is usually considered an important parameter as it dictates the dynamic behavior of soil and also acts as an input parameter for site response analysis, seismic hazard analysis, and site classification. In majority of seismically active areas across the globe, especially in developing countries like Pakistan, the [Formula: see text] measurements are either not available or if available, they are very limited in number to develop a seismic site-conditions map. In the absence of proper geological studies and geotechnical investigation, the slope-derived method provides a simple solution to map the site-conditions. The current study presents the development of slope-derived [Formula: see text] map on the basis of a correlation between [Formula: see text] and topographic slope for active tectonic regions and its comparison with the [Formula: see text] values at various locations in Pakistan. The topographic slope is calculated from digital elevation model (CDEM) of the Shuttle Radar Topography Mission (SRTM) 30 arc-sec global topographic data set. The [Formula: see text] values comprise of directly available, values calculated/estimated from the standard penetration tests (SPTs [Formula: see text]-value) and primary waves at various locations in Pakistan. [Formula: see text] values at various parts/locations in Pakistan and values from the slope-derived [Formula: see text] map are found to be fairly comparable and based on these results for seismically active areas like Pakistan, slope-derived method can be applied for the first-order site-condition studies.

Estimation Study on Shear Wave Velocity of Seabed Using GRNN

2014 ◽  
Vol 580-583 ◽  
pp. 264-267
Author(s):  
Sheng Jie Di ◽  
Zhi Gang Shan ◽  
Xue Yong Xu
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Seismic Analysis ◽  
Site Response ◽  
Estimation Method ◽  
Response Analysis ◽  
Generalized Regression Neural Network ◽  
Engineering Practice ◽  
Site Classification

Characterization of the shear wave velocity of soils is an integral component of various seismic analysis, including site classification, hazard analysis, site response analysis, and soil-structure interaction. Shear wave velocity at offshore sites of the coastal regions can be measured by the suspension logging method according to the economic applicability. The study presents some methods for estimating the shear wave velocity profiles in the absence of site-specific shear wave velocity data. By applying generalized regression neural network (GRNN) for the estimation of in-situ shear wave velocity, it shows good performances. Therefore, this estimation method is worthy of being recommended in the later engineering practice.

scholarly journals An Investigation of Local Site Effects Using Linear and Nonlinear analysis and Comparison Between Them

2016 ◽  
Vol 2 (4) ◽  
pp. 113-122 ◽  
Author(s):  
Ali Komak Panah ◽  
Aylin Nouri
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Earthquake Engineering ◽  
Shear Wave Velocity ◽  
Response Spectrum ◽  
Response Analysis ◽  
Site Classification ◽  
Ground Response Analysis ◽  
Soil Response ◽  
Design Response Spectrum

Recent code provisions for building and other structures (1994 and 1997 NEHRP provisions, 1997 UBC) have adopted new site classification. The new site classification system is based on average shear wave velocity to a depth of 30 m. when the shear wave velocity is not available; other soil properties such as undrained shear strength can be used. The study of propagation damages in various earthquakes illustrates the importance of the site effect on the ground seismic characteristics. From the point of the earthquake engineering view, the most important characteristics of the strong ground motion are amplitude, frequency content and duration. All of these properties have a significant effect on earthquake damage. The behavior of soils under cyclic loading is basically nonlinear and hysteretic. Ground response analysis is used to predict the movements of the ground and develop a design response spectrum in order to determine the dynamic stresses and strains and earthquake forces. The profile was studied by using various methods of soil response analysis and finally, the results were examined. In this paper, soil responses were examined by NERA, EERA software and the results compared with each other. Eventually, we concluded that the values obtained from the EERA are more than the value obtained from the NEERA software.

scholarly journals Parametric Study of Local Site Response for Bedrock Ground Motion to Earthquake in Phuentsholing, Bhutan

2020 ◽  
Vol 12 (13) ◽  
pp. 5273 ◽  
Author(s):  
Karma Tempa ◽  
Raju Sarkar ◽  
Abhirup Dikshit ◽  
Biswajeet Pradhan ◽  
Armando Lucio Simonelli ◽  
...  
Keyword(s):  
Shear Wave ◽  
Ground Motion ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Soil Profile ◽  
Parametric Study ◽  
Site Response ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Geophysical Study

Earthquakes, when it comes to natural calamities, are characteristically devastating and pose serious threats to buildings in urban areas. Out of multiple seismic regions in the Himalayas, Bhutan Himalaya is one that reigns prominent. Bhutan has seen several moderate-sized earthquakes in the past century and various recent works show that a major earthquake like the 2015 Nepal earthquake is impending. The southwestern city of Bhutan, Phuentsholing is one of the most populated regions in the country and the present study aims to explore the area using geophysical methods (Multispectral Analysis of Surface Waves (MASW)) for understanding possibilities pertaining to infrastructural development. The work involved a geophysical study on eight different sites in the study region which fall under the local area plan of Phuentsholing City. The geophysical study helps to discern shear wave velocity which indicates the soil profile of a region along with possible seismic hazard during an earthquake event, essential for understanding the withstanding power of the infrastructure foundation. The acquired shear wave velocity by MASW indicates visco-elastic soil profile down to a depth of 22.2 m, and it ranged from 350 to 600 m/s. A site response analysis to understand the correlation of bedrock rigidness to the corresponding depth was conducted using EERA (Equivalent-linear Earthquake Site Response Analysis) software. The amplification factors are presented for each site and maximum amplification factors are highlighted. These results have led to a clear indication of how the bedrock characteristics influence the surface ground motion parameters for the corresponding structure period. The results infer that the future constructional activity in the city should not be limited to two- to five-story buildings as per present practice. Apart from it, a parametric study was initiated to uncover whatever effects rigid bedrock has upon hazard parameters for various depths of soil profile up to 30 m, 40 m, 60 m, 80 m, 100 m, 120 m, 140 m, 160 m, 180 m and 200 m from the ground surface. The overriding purpose of doing said parametric study is centered upon helping the stack holders who can use the data for future development. Such a study is the first of its kind for the Bhutan region, which suffers from the unavailability of national seismic code, and this is a preliminary step towards achieving it.

PSHA Compatible Probabilistic Seismic Site Response Analysis for Oslo, Norway

2020 ◽  
Author(s):  
Brian Carlton ◽  
Amir M. Kaynia
Keyword(s):  
Velocity Profile ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Site Response ◽  
Epistemic Uncertainty ◽  
Base Case ◽  
Response Analysis ◽  
Soil Profiles ◽  
Shear Wave Velocity Profile

ABSTRACT This article describes a probabilistic site-response analysis for the city of Oslo, Norway. We first perform a probabilistic seismic hazard analysis (PSHA) for hard rock. Then, we conduct site-response analyses using Monte Carlo simulations to capture uncertainty in the site profile. We include four base-case soil profiles to incorporate epistemic uncertainty, and we vary the shear-wave velocity profile and shear-modulus reduction and damping curves to account for aleatory variability. We base the soil profiles on over 7000 in situ tests, and the shear-wave velocity profile median, standard deviation, and interlayer correlation on over 559 cone penetration tests. Next, we perform regression analyses to estimate medians and standard deviations of site-specific amplification factors (AFs). Finally, we modify the ground-motion models for rock with the AFs and recompute the PSHA for the soil surface. The analyses show that (1) shallower soil profiles have larger uniform hazard spectra (UHS) values at short periods and smaller UHS values at long periods; (2) epistemic uncertainty of the base-case soil shear-wave velocity profile leads to alternative UHS values with a difference of a factor of 2 at short periods; (3) there is only a small difference in the mean magnitudes and distances controlling the hazard for the PSHA conducted for rock compared to soil; (4) response spectra calculated from site-response analyses with no aleatory variability of the soil properties predict significantly smaller spectral acceleration values at periods shorter than the natural site period; (5) using site amplification standard deviations based on ground-motion recordings, instead of site-response analyses, results in a 10%–20% reduction in the soil surface UHS at short periods and a 5%–10% increase at long periods; and (6) the Eurocode 8 AFs are, in general, conservative for Oslo.

κ0 for soil sites: Observations from KiK-net sites and their use in constraining small-strain damping profiles for site response analysis

2019 ◽  
Vol 36 (1) ◽  
pp. 111-137 ◽  
Author(s):  
Boqin Xu ◽  
Ellen M Rathje ◽  
Youssef Hashash ◽  
Jonathan Stewart ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Site Response ◽  
Strong Motion ◽  
Small Strain ◽  
Site Amplification ◽  
Site Response Analysis ◽  
Response Analysis ◽  
One Dimensional

Small-strain damping profiles developed from geotechnical laboratory testing have been observed to be smaller than the damping inferred from the observed site amplification from downhole array recordings. This study investigates the high-frequency spectral decay parameter ( κ0) of earthquake motions from soil sites and evaluates the use of κ0 to constrain the small-strain damping profile for one-dimensional site response analysis. Using data from 51 sites from the Kiban-Kyoshin strong motion network (KiK-net) array in Japan and six sites from California, a relationship was developed between κ0 at the surface and both the 30-m time-averaged shear wave velocity ( V s30) and the depth to the 2.5 km/s shear wave velocity horizon ( Z2.5). This relationship demonstrates that κ0 increases with decreasing V s30 and increasing Z2.5. An approach is developed that uses this relationship to establish a target κ0 from which to constrain the small-strain damping profile used in one-dimensional site response analysis. This approach to develop κ0-consistent damping profiles for site response analysis is demonstrated through a recent site amplification study of Central and Eastern North America for the NGA-East project.

Sign in / Sign up

Export Citation Format

Share Document