NI?Zhen-qiang , KONG?Ji-ming , A?Fa-you
2012, 34(3):209-214.
Abstract:In general the failure development process of high slope under seismic action is very short and intense, the failure mechanism is relatively complex. In this paper, a model test is adopted to study the response of intermittent joints rock slope under seismic load. The results in dicate that the maximum strain is on the joints, the strain on upper part of the model is larger than the lower part. The coalescence mechanisms is complex, mostly are tensileshear mixed fail ure. The coalescence of joints didn't imply the destruction of the slope, but destroy the integrity of the slope, and made it in the critical condition. The physical test reveals the response and fail ure mechanism of this type slope under the earthquake action', it will provide a useful reference and guide for theory application and engineering practice.
SHAO?Xiao-yan , LIU?Ning , LI?Ling-ling , HU?Xin-ru
2012, 34(3):215-219.
Abstract:The principle and realization of Ant-Miner algorithm are summarized firstly. Then the Ant-Miner algorithm is analyzed from different views, and an improving and optimizing method are proposed in order to overcome the problems existed in the algorithm. Finally, the improved Ant-Miner algorithm is used in earthquake prediction. The experiments show that, optimization algorithm can achieve better results than C4.5 algorithm.
2012, 34(3):220-223,233.
Abstract:In order to overcome the problem of the uncertain parameters in LSSVM model, the PSO-LSSVM prediction model concerning earthquake forecast is developed, which is based on the particle swarm optimization algorithm with abilities of fast convergence and global optimization. The simulation results show that the proposed method is an effective tool for the prediction of earthquake, and it can effectively enhance the prediction accuracy compared with the way using neural network and support vector machine model.
ZHOU?Min-du , WANG?Chun-rong , ZENG?Rong-sheng
2012, 34(3):224-233.
Abstract:The seismic data including 3 229 local earthquakes (Ms≥l. 5) and 168 teleseismic events occurred during 1980 to 2002 recorded by 130 seismic stations in the seismic networks of Gansu, Qinghai, Ningxia and Sichuan province are collected, and from 55 024 local phases we selecte 51 210 with the maximum travel time residual of 3.0 s, and 2 651 teleseismic phases. The tomographic inversion results show that : ( 1 ) Lower P-wave velocity anomaly exists widely in the lower crust beneath the northeastern margin of the Qinghai-Tibet plateau. Average P-wave velocity in most of the top of upper mantle is 8.05 km/s that is close to the global continental average Pn-wave velocity with 8.1 km/s. It indicates the existence of a clear Moho interface and strong reflections from Moho interface. (2) The epicenters of most strong earthquakes occurred in the research region are located in the lower velocity areas in the 10 km depth range, around thehigher velocity areas in the 30 km depth range and lower velocity areas in the 50 km depth range, which suggests that these areas could be the possible earthquake pregnancy regions. (3) Major fault belts in the region are reverse thrust with strike slip, locate on the transition zones between lower and higher velocity anomalies, and are possibly ultra-crustal faults. (4) The arc belt from Zhangye to Haiyuan and Pingliang and turns to south is possibly the marginal belt of Qinghai-Tibetan plateau, and indicates the platform activation in Alashan platform. (5) The 2D velocity perturbation profile taken from the seismic tomographic results shows fairly agreement with deep seismic sounding profile.
WANG?Qing-min , LIU?Xi-qiang , SHEN?De-xiu
2012, 34(3):234-238,244.
Abstract:Based on the concept of the Voronoi diagram and distribution of earthquake conforming to the distribution of hyperbola approximately, a new methods for earthquake rapid location in the earthquake early warning is presented that using the V-diagram and hyperbola jointly. The earthquakes recorded by the digital seismic network of Qinghai province are relocated with the new method. The result shows that the new method can meet the need of location precision and the timeliness of rapid report in the earthquake early warning, and is better than other ways. So the method has a good prospect of application in the earthquake early warning system.
XU?Jian-sheng , WEI?Yong-gang , ZHANG?Shu-zhen
2012, 34(3):239-244.
Abstract:The kinematics and dynamics characters of Pdif phase in seismic wave from 31 far-teleseism recorded by the broad band digital seismic instruments at CDSN Lanzhou seismic station during 1990-2000 are analyzed. The travel table of Pdif wave at CDSN Lanzhou seismic station is offered for analyzing conveniently. The result is very useful to enhance the rapid earthquake information report ability and accumulate seismic phase analysis experience. It is also helpful to understand physics characters of mantle-core border inner the earth.
YU?Ming-qiu , HU?Bing , ZHANG?Dou-long
2012, 34(3):245-249,263.
Abstract:Cable-stayed bridge with three towers and single cable plane has uniqueness on dynamic behavior in space. In this paper, the Jianbang Yellow River Highway Bridge in Jinan is taken, as example, using finite element method to build spatial dynamic numerical analysis rood bridge, and to form a structural characteristic equation, the space dynamic structure is obtained with frequency range of 1 600-0 cps and frequency shif zos methods for the solution of the equation. The mathematical relationship characteristi t 1 cps by us el of the cs of the ing lancbetween pseudo rela tive velocity response spectrum Sv and pseudo absolute acceleration response spectrum SA is used to select the spectra with basically same characteristic site period in a large number of seismic records, whose peak acceleration and duration are adjusted to directly be input to the dynamic numerical analysis model. Using mass and stiffness factor method in calculation on damping ratio of every vibration type, taking stressed state of the structure under dead load as the initial state,Newmark-β explicit scheme direct integration method with Y≥0.5 and β≥Y/2 which make the method being no-conditional stable is used to the solution of the structure dynamic differential e- quations. Considering the second order effect from dead load in the structure during an earthquake, the numerical solution of nonlinear seismic response is obtained. Furthermore, general laws on seismic response of such bridge type is concluded to provide a feasible basis for seismic design of such bridge type.
CHEN?Zhen-xun , XIN?Xiao-long , HE?Rui-chan
2012, 34(3):250-255.
Abstract:Using the Mann-Kendall method, an abnormal analysis of some index data sequences collected from Jingyang Ms4.8 earthquake in 1998 and Gaoling Ms4.4 earthquake in 2009 is done. Analyse results show that some indexes of the precursory observation data of earthquake appeared abnormal change. Applying this method, the time of change-point can be identified. The works have impacted on earthquake forecast.
LI?Jie , WANG?Xiao-qiang , WANG?Qi , FANG?Wei , SONG?He-ping
2012, 34(3):256-263.
Abstract:Using the data of GPS measurements, the velocity field of present crustal movement before the Yutian MsT. 3 earthquake in 2008 in the Western KunIun tectonic zone, Xinjiang region, is calculated, and the active rates of regional maijor faults are estimated by analyzing the velocity field. The result shows that the active feature of Longmucuo fault at south of the earthquake epicenter is left-lateral strick sliping with rate of 1.2-2.5 mm/a, the sliping rate of Altyntagh left-lateral fault at north of the epicenter is about 5 mm/a, and the sliping rate of Kangxiwa left-lateral fault at northweast of the epicenter is 3-7 mm/a. The distribution of regional strain field is affected in some extent by the distribution of faults in the region. Yutian MsT. 3 earthquake occurred at faults intersection zone and also the maximum shear strain rate zone.
JIA?Peng , ZHANG?Xi , ZHANG?Xiao-liang , JIANG?Feng-yun
2012, 34(3):264-267,273.
Abstract:Based on the horizontal velocity data observed by GPS during 2004-2007 and 2007-2009, before and after the Wenchuan earthquake, in Sichuan-Yunnan region and adjacent area, the tectonic deformation evolution features of the crust and main active fault belts, and possible influence from the Wenchuan great earthquake, are analyzed. The result shows that the Wenchuan earthquake area showed obvious co-seismic thrust and dextral deformation during the period of 2007-2009. The earthquake, in a certain extent, promoted tectonic movements in Gansu-Sichuan boundary area, as well as West Qinling Mountain area and Anninghe-Zemuhe faults. Meanwhile, impacted tectonic movement on Xianshuihe fault with adjustment overall but may increase the southern section of it.
2012, 34(3):268-273.
Abstract:Through selection the broadband digital seismic data from April 25,2008 to May 12, 2008, recorded by fourteen seismic stations in Sichuan province, the microtremor wave form records are transformed to displacement wave forms after the data correction and filtering. The results of Fourier analysis indicate that before the earthquake occurred the low-frequency abnormal quiver is found; Fourier spectrum value at 0. 1 -0.3 Hz band is increased in two to three days. Amplitude values of displacement waves are gradually increased at every seismic stations. The microtremor records change greater at stations near the Longmenshan fault zone.
GAO?Ling , LIN?Yuan-wu , YANG?Ming-bo
2012, 34(3):274-276,288.
Abstract:The release gas in Wuliying well, Yanqing county of Beijing, is N2, with minor gases He, CH4, Rn, CO2, Ar. The ratio of Nz/Ar is 46. 3 and ratio of 3He/4He is 2.4 Ra, which show that it mixted by deep mantle-origin conponents. The facts of CH4 content is 2.2%, and CO2 (TCD) is 4.9 mg/L show the hot water release activity under strong reduction environment, which corresponds the gas-release background field characteristicsed by reduction-oriented gas release activity in Yanhuai basin where the well located in. It also shows that the gas release in Wuliying well tends to be a themal-reservoir type, rather than a fault type, reflected by Helium observation and the abnormal release of Helium density before and after two strong earthquakes. It suggests that the time of deep gas with themal-reservoir type entering themal-reservoir lags than the fault type, and disappears much later than fault type does also. This is different from the gas release characteristics in Dahuichang well which located near Babaoshan fault at Fengtai area of Beijing.
XIE?Zhuo-juan , LU?Yue-jun , ZHANG?Li-fang
2012, 34(3):277-283.
Abstract:The energy density values of moderate-small earthquakes since 1970 in Longmenshan seismic belt and its adjacent region are calculated. The characteristics of distribution image of moderate-small earthquakes are analyzed quantitatively, and its relationship with the distribution of historical strong earthquakes and main fault zones, as well as with seismic belt boundaries are discussed. The result provides a quantitative base from moderate-small events to validity of the new division scheme of seismic zoning in Longmenshan area. In addition, the minimum completeness of magnitude Mc are given for each periods in the research area by completeness analysis for moderate-small earthquake data using the magnitude-frequency relation (Gutenberg-Richter relation). The result provides a quantitative base for division of seismic belt in this region ,and can be a reference for seismicity analysis and earthquake risk evaluation.
LI?Xin , GUO?An-ning , JIAO?Jiao
2012, 34(3):284-288.
Abstract:Based on the basic theory of disaster and the fuzzy comprehensive evaluation model, an assessment model of economic vulnerability caused by earthquake disaster is established, and the vulnerability factor indices set and remark set are constructed. Using the model 13 main cities in G-ansu province are taken as examples to do the assessments. The results show that Lanzhou, Jinchang, Tianshui, Wuwei, Zhangye have the highest economic vulnerabilities, and Pingliang, Jiuquan, Dingxi and Gannan have the lowest ones. As the influence of assessment indices on assessment target is fuzzy, the method is appropriate.
FENG?Jian-gang , JIANG?Chang-sheng , HAN?Li-bo , HONG?De-quan
2012, 34(3):289-293,312.
Abstract:In order to preserve the recording data of Gansu seismographic network and explore their research values, we have collected and reestablished the earthquake observation reports of the Gansu Seismographic network in paper redium since 1970, and changed them to the electronic files. Some problems we met in the work are discussed. Using the Hypoinverse method we relocated 23 272 earthquakes events, and analyzed the results, evaluated its errors, comparied the resuits with initial results.
JIAO?Jiao , GUO?An-ning , GAO?Si-ru , LI?Xin
2012, 34(3):294-298.
Abstract:The observation data from stations near the Liujiaxia and Longyangxia reservoirs before some earthquakes are analyzed. It is shown that if earthquake observation points near the reser- voir or natural lake, the precursory phenomena are more prominent. In this paper, the possible mechanism of this phenomena is discussed. It is indicated that we can use the stations near reservoir and natural lake to predict earthquake near the lake or in a large area for short-imminent term.
LIU?Hong-bin , YIN?liang , LI?Dong-sheng , LI?Xin-jian , LIU?Xiao-ming , ZOU?Xiao-bo
2012, 34(3):299-307.
Abstract:The observation data of 4-component borehole strainmeter at Gaotai base seismic station, Gansu province, have been stable, continuous and reliable since it was set up in 2007. It is found that different types of the precursory waves appeared before some strong earthquakes, such as sudden rise, sudden plunge, tidal distortion and microtremor bold, etc. In this paper the precursory waves before some strong events are introduced, and the mechanism of the wave is discussed also.
PENG?Xiao-tong , DENG?Wen-bin , LI?Sheng-ling
2012, 34(3):308-312.
Abstract:Before earthquake the radiant heat from the crust can cause atmosphere appears irregular information. Sounding data reflects"exotic" atmospheric structure and super instability. In this paper, V-3t) diagram is used to analyse the atmospheric structure before Yushu earthquake and normal situation, and the temperature information is digitized. The result proves the Ouyang Shoucheng forecasting theory: energy accumulation will inevitably involve non-uniform in physical structure and irregurlar information will inevitably involve event head-turning change.
Sopyright:China Earthquake Engineering Journal