To estimate the near-fault inelastic response spectra, the accuracy of six existing strength reduction factors （R） proposed by different investigators were evaluated by using a suite of near-fault earthquake records...To estimate the near-fault inelastic response spectra, the accuracy of six existing strength reduction factors （R） proposed by different investigators were evaluated by using a suite of near-fault earthquake records with directivity-induced pulses. In the evaluation, the force-deformation relationship is modelled by elastic-perfectly plastic, bilinear and stiffness degrading models, and two site conditions, rock and soil, are considered. The R-value ratio （ratio of the R value obtained from the existing R-expressions （or the R-p-T relationships） to that from inelastic analyses） is used as a measurement parameter. Results show that the R-expressions proposed by Ordaz ＆ Perez-Rocha are the most suitable for near-fault ground motions, followed by the Newmark ＆ Hall and the Berrill et al. relationships. Based on an analysis using the near-fault ground motion dataset, new expressions of R that consider the effects of site conditions are presented and verified.展开更多
A trapezoid valley site is chosen as a research site,and according to numerical models based on orthogonal design,the factors influencing ground motion in the valley site are studied with two-dimensional finite differ...A trapezoid valley site is chosen as a research site,and according to numerical models based on orthogonal design,the factors influencing ground motion in the valley site are studied with two-dimensional finite difference method. The influencing factors are ranked,and then the calculation results are verified by ground motion analysis. The conclusions are as follows:there are four factors that have important effects on ground motion of trapezoid valley sites,but the effects are different as the location of sites changes,the influencing factors rank differently with different site locations; The ranking of the influencing factors is the same for all the sites located within a distance of 40m from the valley's side,among them,the most effective one is the valley slope angle ranks,followed by depth-to-width ratio,overburden thickness,at last the input ground motion intensity.The impact of the factors on surface ground motion is roughly the same in the valley sites within a certain distance to the valley side,and the geometric parameters of the valley terrain play a greater part in influencing ground motion. With the increase of distance away from the valley's side,the ranking of the influencing factors also changes,the rating of slope angle moves backward,the ranking of the input ground motion and overburden thickness move ahead. The effect of valley geometric parameters on ground motions is gradually weakened,but the effect of other two influence factors are gradually increased,similar to cases of a horizontal layered site. Strong motion records in Anning River valley site were analyzed,and the results show that the valley topography has a significant amplification effect on ground motion,and that the numerical results of this paper are credible.展开更多
Based on the daily observation data of shallow ground temperature, total cloud cover, precipitation, evaporation capacity and frozen soil of 5 stations in Shijiazhuang from 1981 to 2010, using methods such as linear t...Based on the daily observation data of shallow ground temperature, total cloud cover, precipitation, evaporation capacity and frozen soil of 5 stations in Shijiazhuang from 1981 to 2010, using methods such as linear trend and complete correlation coefficient, relation between variation characteristics and climatic influencing factors of shallow ground temperature was analyzed to lay the foundation for studying impact factors of shallow ground temperature and provide references for daily maintenance of automatic observation business. The results showed that fluctuant variability and fluctuant range of mean shallow layer ground temperature in Shijiazhuang became smaller with soil layer being deeper for all years and seasons, and the fluctuant variability was maximal in spring and minimal in winter, while the fluctuant range was maximal in summer and minimal in winter; mean shallow layer ground temperature for all years had a warming trend with an obvious warming trend in winter, and warming range in winter was smaller and the extent was weaker with soil layer being deeper while a cooling trend occurred in summer; there was a coincident trend between total cloud cover at night and shallow ground temperature in winter, and between evaporation capacity and shallow ground temperature in summer, while there was an inconsistent trend between maximum depth of frozen soil, period of freezing weather and shallow ground temperature in winter, and between total cloud cover in the davtime, orecioitation and shallow around temperature in summer.展开更多
基金Foundation for Research and Science and Technology of New Zealand, Contract Number: C05X0208 and C05X0301the Foundation for Western Transportation Science and Technology Research, Contract No. 200831800098
文摘To estimate the near-fault inelastic response spectra, the accuracy of six existing strength reduction factors （R） proposed by different investigators were evaluated by using a suite of near-fault earthquake records with directivity-induced pulses. In the evaluation, the force-deformation relationship is modelled by elastic-perfectly plastic, bilinear and stiffness degrading models, and two site conditions, rock and soil, are considered. The R-value ratio （ratio of the R value obtained from the existing R-expressions （or the R-p-T relationships） to that from inelastic analyses） is used as a measurement parameter. Results show that the R-expressions proposed by Ordaz ＆ Perez-Rocha are the most suitable for near-fault ground motions, followed by the Newmark ＆ Hall and the Berrill et al. relationships. Based on an analysis using the near-fault ground motion dataset, new expressions of R that consider the effects of site conditions are presented and verified.
基金sponsored by the National Natural Science Foundation of China(51508096)the Spark Program of Seismological Science and Technology,CEA(XH15067Y)
文摘A trapezoid valley site is chosen as a research site,and according to numerical models based on orthogonal design,the factors influencing ground motion in the valley site are studied with two-dimensional finite difference method. The influencing factors are ranked,and then the calculation results are verified by ground motion analysis. The conclusions are as follows:there are four factors that have important effects on ground motion of trapezoid valley sites,but the effects are different as the location of sites changes,the influencing factors rank differently with different site locations; The ranking of the influencing factors is the same for all the sites located within a distance of 40m from the valley's side,among them,the most effective one is the valley slope angle ranks,followed by depth-to-width ratio,overburden thickness,at last the input ground motion intensity.The impact of the factors on surface ground motion is roughly the same in the valley sites within a certain distance to the valley side,and the geometric parameters of the valley terrain play a greater part in influencing ground motion. With the increase of distance away from the valley's side,the ranking of the influencing factors also changes,the rating of slope angle moves backward,the ranking of the input ground motion and overburden thickness move ahead. The effect of valley geometric parameters on ground motions is gradually weakened,but the effect of other two influence factors are gradually increased,similar to cases of a horizontal layered site. Strong motion records in Anning River valley site were analyzed,and the results show that the valley topography has a significant amplification effect on ground motion,and that the numerical results of this paper are credible.
文摘Based on the daily observation data of shallow ground temperature, total cloud cover, precipitation, evaporation capacity and frozen soil of 5 stations in Shijiazhuang from 1981 to 2010, using methods such as linear trend and complete correlation coefficient, relation between variation characteristics and climatic influencing factors of shallow ground temperature was analyzed to lay the foundation for studying impact factors of shallow ground temperature and provide references for daily maintenance of automatic observation business. The results showed that fluctuant variability and fluctuant range of mean shallow layer ground temperature in Shijiazhuang became smaller with soil layer being deeper for all years and seasons, and the fluctuant variability was maximal in spring and minimal in winter, while the fluctuant range was maximal in summer and minimal in winter; mean shallow layer ground temperature for all years had a warming trend with an obvious warming trend in winter, and warming range in winter was smaller and the extent was weaker with soil layer being deeper while a cooling trend occurred in summer; there was a coincident trend between total cloud cover at night and shallow ground temperature in winter, and between evaporation capacity and shallow ground temperature in summer, while there was an inconsistent trend between maximum depth of frozen soil, period of freezing weather and shallow ground temperature in winter, and between total cloud cover in the davtime, orecioitation and shallow around temperature in summer.
