CHEN Shu-jun , ZHAO Qi-le , ZENG Zuo-xun , DU Rui-lin
2005, 27(1):1-7.
Abstract:The Discontinuous Deformation Analysis ( DDA ) method has shown much convenience in reflecting the deformation characters while Discontinuous Finite Element Method (DFEM) can more delicately reflect the tectonic plates interaction. In view of advantages of both DDA method and DFEM, firstly, we analyze the behave of the tectonic blocks in Chinese mainland by DDA method and obtained the boundary condition from measured movement from data of 308 GPS stations. Then based on the boundary condition we make a two-dimension DEFM model and used it to evaluate how the slipping along Altyn Tagh fault effects the tectonic deformation and stress filed in Chinese mainland.
2005, 27(1):8-12.
Abstract:When the bridge piers with shallow foundation subject to strong earthquake action, the uplift of foundations will occur and the foundation soil will enter to plasticity, meanwhile the structure will enter to nonlinear state and is damaged. It is very difficult to simulate the uplift and yield of supporting soil using an accurate method. In this paper,an improved Winkler foundation model, which could be used to consider uplift and yield, is employed in the seismic response analysis. Taking the project of Xiaoxihu Yellow River Bridge in Lanzhou city as the example,an artificial seismic wave with the site transcendental probabity 10% level is inputted and the nonlinear history responses are obtained. The result shows that the displacement on top of the pier increases and the moment at bottom of the pier decreases, the piers will yield whert meat strong earthquake, but its curvature will not bead constructure. So the goal of three-level aseismic design can be meat.
2005, 27(1):13-16.
Abstract:The undrained strength of saturated clay will decrease during undrained cyclic loading. Sometimes serious damages to structures sited on clay layers and filled road pavements are occurred in earthquakes. In this paper, based on the over-consolidated undrained strength, a cyclic loading-induced degradation parameter is introduced, and the calculation methods for cyclic shear strength of saturated clay and the parameters are proposed. Meamwhile, the effect of reconsolidation index to the post cyclic shear strength increment is analyzed. According to the undrained cyclic triaxial tests, the proposed method is verified available. The method will be effective to predict the cyclic shear strength and stability of clay layers.
RONG Dai-lu , ZHANG Yuan-sheng , LI Ya-rong
2005, 27(1):17-21.
Abstract:The falling process of Lanzhou meteorite in Dec. 11, 2004 is conversed and analyzed using the seismic data recorded by the Lanzhou temporal digital network set by Seismological Bureau of Gansu Province. The results show that the meteorite came into the sky above Lanzhou through 26 km high at 23:36:23 in Dec. 11, 2004, and a small explosion occurred, then the fireball fell down towards to the north-east direction, arrived its endpoint and exploded and disjointed into Key words: small ones Meteorite; at 23:36:42 at 13 km high. No big ones fell down to the ground Lanzhou area; Seismic records
SATO T , MATSUMARU T , MOON Y , ZHANG F , UZUOKA R
2005, 27(1):22-29.
Abstract:Loose saturated sand behaves as a solid before liquefaction but as a fluid when the excess pore water pressure reaches the initial confining stress, after which it recovers its strength. Those processes cannot be treated independently,but should be considered continuous processes that represent change from the solid to fluid state or from the fluid to solid state. Therefore, the total processes of the combined liquefaction-ground flow phenomenon should be treated as a series of processes of phase transformation between the solid and fluid states. In this paper, a simple constitutive equation for loose saturated sand was developed to be able to express the phase transformation between a solid and fluid during liquefaction and the ground flow phenomenon. This constitutive equation was used for a dynamic analysis of a pile-ground system,and its applicability investigated by comparing with the elasto-plastic constitutive equation.
2005, 27(1):30-35.
Abstract:The macroseismic equation,giving the convergent solution(regardless of magnitude) for relative intensity at lg R-0,was derived. Investigation of seismically resistant characteristics of rocks in the Baikal region together with literary data and unified theory allowed one to evaluate the equipotential source surface. The constancy of earthquake intensity at the boundary of a source,the radiator of elastic waves in the crust,is established. This made it possible to carry out transition from the main parameter of an earthquake, the magnitude, to the quantitative calculation of intensity with distance from a source. Bilinear dependence of intensity(density of energy flux) on a distance is obtained. Correlation between density of energy flux and relative intensity is given. Intensity of oscillatory loads depending on physical characteristics of grounds-building bases was derived. The proposed method of quantitative prediction of large seismic effects in seismological aspect is one of the possible methods to provide the detailed seismic zoning and microzoning of the territories.
ZHANG Zhen-zhong , ZHANG Dong-li , LIU Hong-mei
2005, 27(1):36-41,46.
Abstract:In this paper, the forming conditions of seismic subsidence of loess, the characteristics of seismic disaster, the basic properties of loess including water collapsibility relating to 1995 Yongdeng MsS. 8 earthquake are discussed. The relationship between the static and dynamic parameters of loess and its seismic subsidence is also revealed. Using calculating method of predicting amount of seismic subsidence and 3D finite element method, proposed theory and method of seismic subsidence is validated and the seismic subsidence in 1995 Yonddeng 5.8 earthquake is explained.
ZHONG Ju-fang , HU Xiao , QU Tie-jun , WU Sheng-xing
2005, 27(1):42-46.
Abstract:Based on three large earthquake acceleration records collected in SMART 1 array in Taiwan, the values of envelope function of vertical ground motion and parameters in the function are calculated. The spatial variabilities of each parameters of the function are analyzed, and the experential prediction formulas are suggested.
WU Chuan-yong , SHEN Jun , ROU Jie , XIE Tian , LUO Fu-zhong , RUANCheng-wen , LIU Jing-yuan
2005, 27(1):47-51,70.
Abstract:The Fukang-Jimsar fault, a Holocene active fault, is considered as a borderline fault between Bogeda Mountain and piedmont alluvial-pluvial fans. Piedmont alluvial-pluvial fans and low terraces of rivers were bended in different degrees since the middle and late Holocene. The fault cross-section near Dalongkou indicates there were three paleoseismic events during late Pleistocene, and the recurrence interval of earthquake on the east segment of the fault is 4500 -7500 a. The obliquity of the Fukang-Jimsar fault inclination decreased when it reached the ground, and scarps on the surface were formed by the bending strata. The section reveals the ways of displacemental diminishment and deformation distribution near the ground.
WANG Xiao-ping , ZHU Yuan-qing , SONG Xiou-qing , YU Hai-ying
2005, 27(1):52-55.
Abstract:Based on the teleseismic events which were recorded by shanghai seismic array and using seismic array process technology, the split of PpSmS, P660S and SKS phases are studied. The split parameters of PpSms,P660S and SKS are calculated ,the mantle and crust medium anisotropies under shanghai seismic array region are analyzed briefly according to the difference among PpSmS, P660S and SKS split parameters .
LIU Xiao-feng , XIAO Li-zhu , MEI Xiu-ping , XU Huei
2005, 27(1):56-60.
Abstract:The moderate-strong earthquakes in Qilianshan seismic belt shows the character of becoming groups. The seismicity patterns before the main shock are seismic gaps,precursor earthquakes, and enhanced regional seismicity, et al.. The seismic gaps mostly are mid-term abnormity. The signs from mid-term to short-term are those precursor earthquakes occur at the edge of or in the gaps, the gaps cease for 1-3 months, or the gaps dissemble with the small earthquake occurrs in it. The precursor earthquakes generally occur 1-6 months before the main shock and the distances between the precursor earthquake and main shock are less than 30 km, with the △M=1.5-3.0. Furthemore, the earthquake sequence patterns, the b,h values of the aftershock sequences are statisticsed and analysed. All above reseach will serve in seismic trend prediction after strong earthquake.
ZHENG Wen-jun , LIU Xiao-feng , ZHAO Guang-kun , MA Er-man
2005, 27(1):61-65.
Abstract:Based on the date of field investigation after Minxian Ms5.2 earthquake on Nov. 13, 2003, Gansu province, the principal parameters, intensity, damage, seismogenic tectonics of the earthquake are summed up, and principal cause of higher intensity and strong damage on the earthquake are analyzed.
MAO Yan , YU Wei-xian , WANG Bin
2005, 27(1):66-70.
Abstract:Based on the data of seismogeology, geophysics and crustal deformation in contral and eastern Yunnan province in recent years,the 15 characteristic parameters which are closely correlated to strong earthquakes are analysed and selected. Among the 15 parameters, 12 are choosed by sieving method of pattern distinction as the final parameters. Using the means of synthetic pattern distinction, 47 potential seismic focus areas for M≥ 6 earthquake from 100 studying areas are determined. Then,27 potential seismic focus areas for M≥7 earthquake are obtained from 49 studying areas in which the M 6 earthquakes have occurred or will occure possibilly. On this foundation, a predictive map of potential seismic source areas for moderate-strong earthquake in Central and eastern Yunnan province is put forward.
REN Jun , CHEN Yun-ping , PAN Ji-shun , SHEN Fan-luan , FU Gan
2005, 27(1):71-74.
Abstract:Using the seismic strain energy as the response factor, the anomalous characteristics of Load/Unload Response Ratio before moderate-strong earthquakes in Hainan Island and its adjacent area are analysed. The research result indicates that the high anomaly of LURR is a kind of medium-term and short-term precursor before moderate-strong earthquake in this region. It could be a new method for earthquake prediction.
MENG Zhi-min , XIE Jia-shu , ZHANG Xian
2005, 27(1):75-79.
Abstract:According to the method of power spectrum analysis of indivi sing the wide-band digital waveform data recorded by Shaanxi digital s Qc values of coda wave in 13 frequency bands in Guanzhong, Shannan a estimated. The result shows that the coda Qc values are in range of 37. age value of 58.44 in the 2ts-35 s time window,and are higher in Qinli dual dispersion model, u where the ascending motion is marked, otherwise are lower in Guanzhong basin and Shannan area. In the 2ts-70 s time window, the Qc values are in range of 194.74-283.50 with the average value of 186.79,and are higher in wave highvelocity area of moho-discontinuity comparing with lower values in wave lowvelocity area and lowvelocity gradient belt.
2005, 27(1):80-84.
Abstract:The characteristic of medium- small earthquake activity ( 3.0≤ML ≤ 5. 0 ) from 1982 in northern Shanxi province is analysed. It is found that 1-2 years before 1989 Datong-Yanggao ML6. 1 earthquake, 1996 Baotou ML6. 4 earthquake and 1998 Zhangbei ML6. 2 earthquake, the yearly frequencies of medium-small earthquake active showed obviously the process of in creasing-decreasing-main earthquake occuring. The strip-like seismic activities in areas near the main-shock before the event have the mean of predicting main-shock position,meanwhile the seismicities in the areas far from main-shock can only present the increasing of stress field level. The active of medium-small earthquake often move to the area where a strong earthquake would occur.
2005, 27(1):85-88.
Abstract:The research history of earthquake-tsunami in China is in troduced and a synthetical review is given in this paper. Meamwhile the disater prevention problems for future earthquake- tsunami and other disasters in China are discused.
LU Ming-yong , NIU An-fu , LU De-shun , ZHANG Xiu-kui
2005, 27(1):89-95.
Abstract:The mutual relation and influence between the crustal deformation and the subsurface fluid are present obviously. The abnormality of crustal deformation is the most direct reflection of crustal tectonic change, and also is one of the most definite seismic precursor on physical meaning,and the anomaly of subsurface fluid can provide polytype precursory information on tectonic active process (as well as earthquake). This two types of anomaly can reflect precursory information in the development process of earthquake by different ways and features, thereforce become the important methods of seismologic prediction. In this paper, the research achievements of anomalous characteristics is summarised, the interrelation of two types of anomaly is concluded from their mechanism and precursory anomalous characteristics.
YANG Dong-hong , YANG Xue-xiang
2005, 27(1):96-96.
Abstract:根据美国西北大学地质科学系SethStein和EmileOkal最近在全球地震联合会(IRIS)网站公布的计算结果,2004年12月26日印度尼西亚苏门达腊地震震级为Mw9.3,使该地震成为有地震仪器观测史以来的排列第2的大地震(排列第一的是1960年智利Mw9.5地震).
Sopyright:China Earthquake Engineering Journal