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Tan H.,Hohai University | Gao Z.,Institute of Earthquake Engineering of Jiangsu Province
Disaster Advances | Year: 2012

Based on the results of the resonant column test in lab and shear wave velocity test in situ of 463 saturated clayey soil samples and 233 saturated sandy soil samples in Jiangsu areas, the comparison of maximum dynamic shear modulus Gmax values from the different tests has been discussed. The comparison result shows that the differences of Gmax value respectively obtained from lab test and situ test are very great and the G max values got from situ test are almost larger than those of lab test, especially with the increase of soil depth. Furthermore, the analysis on test results also shows the Gmax value of lab test is exponential to the depth in statistic and the statistical formula of Gmax value in lab test and shear wave velocity Vs in situ test has also been proposed. Source

Peng X.,Institute of Earthquake Engineering of Jiangsu Province | Peng X.,China Earthquake Administration | Li X.,China Earthquake Administration | Liu Q.,China Earthquake Administration
World Information on Earthquake Engineering | Year: 2011

According to the review of coseismic displacements estimated from strong-motion accelerograms since 1940,the related theory and methods are systematically summarized. The importance of the coseismic displacement and common drifting phenomenon are discussed at first. Then the effort for estimating the displacement based on accelerograms from analog phase to digital phase is presented mainly in chronological sequence. Next the noise causing drifting is divided into five models,and two kinds of corresponding estimation methodsfitting by three kinds of time histories and by two kinds of wavelet analyses are discussed. Finally, the prospects of future researches are expounded. Source

Tan H.,Hohai University | Huang Y.,Institute of Earthquake Engineering of Jiangsu Province | Chen J.,Hohai University
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013

The disastrous geology survey in water areas for underwater pipeline construction has been finished with the acoustic strata profile technique. The strata profile has been obtained, which shows the bedrock is consecutive and no fault exists in the exploration area. The existence of at least two pipelines has been proved, and the depth of the previous pipelines is in the middle of sand layers. Therefore, the suggestion of pipeline construction at the depth of about 40m below the water level has been proposed to avoid the cobble layer and provide a covering layer to prevent pipelines from erosion by currents. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE). Source

Liu B.,Institute of Disaster Prevention | Wang W.,Institute of Disaster Prevention | Peng X.,Institute of Earthquake Engineering of Jiangsu Province | Zhou Z.,Nanjing University of Technology | And 2 more authors.
International Journal of Earth Sciences and Engineering | Year: 2015

During Wenchuan Earthquake in 2008, the PGA (Peak Ground Acceleration) and spectral characteristics of main shock detected by the observation stations in Baoji, Fengxiang, Chencang and Qishan in the west of Weihe Basin differed greatly. The PGA of observation stations at Fengxiang and Qishan located in the loess tableland in the north of Weihe Fault were obviously smaller than those in Chencang station and Baoji station in the river valley plain in the south of Weihe Fault. The high-frequency components of Chencang station were much more abundant than those at Fengxian station and Qingshan station. However, these four stations are only a dozen kilometers away from each other. As shown by seismogeological data and the information of the observation stations, these stations are not significantly different in local site conditions. Considering the fact that these stations are three to four hundred kilometers away from Longmenshan Fault, the causative fault of Wenchuan Earthquake, such large differences in PGA cannot be explained by the ground motion attenuation law in this area. In this study, by using the seismogeological features and local topography, the 2-D model of those sites derived by the explicit finite element combining with local multi-transmitting artificial boundary method is used to analyze the mechanism of difference of the ground motion. Numerical simulation indicates that the presence of rock base mountain, fault scarp, fault fracture zone and overburden, which are heterogeneous media, leads to violent waveform transformation in this area. Under the double influence of scarp and fault fracture zone, the transformed wave component is the largest near the fault scarp. Under the double influence of thick and deep overburden in the center of the river valley and the basin effect, the response is the largest at Chencang station near the center of the river valley. Ground motion is significantly amplified in the scarp and loess tableland within the low-frequency range of 1-2Hz and the highfrequency range above 5Hz. For the medium-frequency range of 3-5Hz, ground motion is greatly amplified in the river valley plain. Moreover, the magnitude of amplification is basically consistent for certain frequency range. Thus, macroscopic analysis and numerical analysis indicate that the difference of the ground motion is mainly affected by dislocation basin, fault scarp and fault fracture zone under control of the non-causative fault(Weihe Fault) in Wenchuan Earthquake. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved. Source

Ding X.-M.,Hohai University | Tan H.-M.,Institute of Earthquake Engineering of Jiangsu Province
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2011

In order to obtain the dynamic response of defective large-diameter pipe pile in low strain integrity testing when subjected to transient concentrated load, a computational model and wave equation of large-diameter pipe pile with variable wave impedance were established based on radial invariability assumption. The analytical solution of wave equation in frequency domain was obtained by Laplace transformation method. The dynamic responses in time domain were obtained by Fourier inverse transformation. The results of analytical solution were compared with that of 3D finite element method and 1D wave theory. The results indicated that the results of analytical solution well matched the 3D-FEM results. The velocity responses at 90°point calculated by 3D-FEM, analytical solution and 1D wave theory had little difference. The dynamic responses at different points on top of the pile showed that the arrival time of incident wave crests varied with radius angle. The smaller the radius angle, the earlier the arrival time. The arrival time of defect reflected wave crests was different among different points when depth of defect was not very deep. However, the difference was decreased when the defect was deeper. The high-frequency interference was the least at 90°point. The results of the analytical solution could well meet the measured results. Source

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