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Cai C.,Hohai University | Gao Y.-F.,Hohai University | Zeng L.-L.,Fuzhou University | Hong Z.-S.,Nanjing Southeast University | Tao C.-F.,Seismological Bureau of Anhui
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2012

A series of falling head hydraulic conductivity tests were performed on natural Wenzhou clays consolidated at different stress levels using modified oedometric apparatus to investigate the change law of hydraulic conductivity of natural clays during compression. It was found that both the compression behavior and the hydraulic conductivity behavior are significantly affected by the yield stress caused by the soil structure formed during the depositional and post-depositional processes. When the consolidation pressure is less than yield stress, the compressibility is small and the variation of hydraulic conductivity is not obvious. When the consolidation pressure is larger than yield stress, the compressibility increases dramatically and the hydraulic conductivity varies clearly with the stress level. The change of hydraulic conductivity with the increase in stress level was discussed, and a method of predicting hydraulic conductivity during compression was proposed.

Li J.,Seismological Bureau of Anhui | Li J.,National Geophysical Observatory at Mengcheng | Li Q.,Institutes of Geophysics | Yang D.,Institutes of Geophysics | And 6 more authors.
Data Science Journal | Year: 2011

Principal component analysis is applied to analyze the horizontal component of geomagnetic data for the Panzhihua Ms 6.1 earthquake. We investigate temporal variations in eigenvalues and find that only the first principal component has good correlation with the Ap index for which the cross-correlation correlation R is larger than 0.6, which may imply solar-terrestrial activity. Both the second and third principal components show clear daily variation, being high during work hours and low at night and on weekends. The mean eigenvalue of the third component at night (00:00-04:00 LT) increased about 40 days before the earthquake and returned to normal 10 days before the earthquake. These features are likely to be correlated with the earthquake.

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