锦州地震台体积式钻孔应变仪的映震情况     

明成山  李京锦  李哲 《地震地磁观测与研究》2005,(Z1)

论述了张北MS6.2、沈阳ML4.1、内蒙古ML5.9、日本北海道MS8.0、俄蒙中交界MS7.9、青海昆仑山MS8.1地震前后,锦州地震台体积式钻孔应变仪观测震前异常的变化规律。通过计算潮汐因子、振幅因子、3点线性平滑滤波残差值等方法,识别异常。结果表明,体应变异常资料与地震有一定的相关性。  相似文献   

Strain accumulation in sand due to cyclic loading: drained triaxial tests     

T. Wichtmann  A. Niemunis  Th. Triantafyllidis   《Soil Dynamics and Earthquake Engineering》2005,25(12):967-979

Our aim is the prediction of the accumulation of strain and/or stress under cyclic loading with many (thousands to millions) cycles and relatively small amplitudes. A high-cycle constitutive model is used for this purpose. Its formulas are based on numerous cyclic tests. This paper describes drained tests with triaxial compression and uniaxial stress cycles. The influence of the strain amplitude, the average stress, the density, the cyclic preloading history and the grain size distribution on the direction and the intensity of strain accumulation is discussed.  相似文献   

Tidal Stress/Strain and the b-values of Acoustic Emissions at the Underground Research Laboratory, Canada     

Takaki Iwata  R. Paul Young 《Pure and Applied Geophysics》2005,162(6-7):1291-1308

The correlation between the b-values of acoustic emissions (AEs) and the phase of the moon was investigated at the Underground Research Laboratory (URL) in Canada. The same data as those used in Iwata (2002) were examined, which showed that the occurrence of AEs is correlated with the phase of the moon. It was expected, therefore, that the b-value of the AEs would also be sensitive to tidal stress/strain fluctuations. We investigated the variation of the b-values as a function of the phase of the moon. Results show that b-values immediately following the times of full/new moon are higher than those at other times. Using AIC (Akaike Information Criterion) and random (Monte Carlo) simulations, it was confirmed that this feature is statistically significant. We also investigated whether or not there was a change in the b-values immediately before the times of full/new moon, but no statistically significant change was observed. The results suggest that the effect of stress/strain fluctuations on AE occurrences at the URL is asymmetric to the times of full/new moon.All authors are members of the Academic Robotics Group. In listing The Academic Robotics Group, the authors are endeavoring to place each of the participant institutions on an equal footing in terms of effort and authorship. M. A. Talamini is serving as presenter.  相似文献   

采空区二维超声波物理模型实验研究     

赵家福  田钢  石战结  王者江 《吉林大学学报(地球科学版)》2005,(Z1)

由于对资源矿产的过度开采使得矿山地区(尤其是煤矿)出现了采空区,从而引起地表塌陷等地质灾害。为了深入了解地震方法在采空区调查中的应用效果,从超声波物理模型实验研究出发,论述了物理模型的原理和制作,研究了采空区的地震波场特征,并利用W inse is软件对所采集的二维超声波实验数据进行了处理。由叠偏剖面推断的采空区的位置与实际模型相符,从而验证了超声波采空区物理模型试验是有效的、可信的;同时可以为实际探测采空区提供进一步的理论依据。  相似文献   

桂林地区古人类演化及环境变迁研分     

王华  杨琰  张会领 《地球学报》2005,26(Z1):205-208

桂林地区曾是古人类活动活跃的地区，据可以断代的古人类洞穴遗址统计，发现桂北地区大部分的洞穴遗址其年代的下限都在距今约7000a 左右，此后古人类离开了洞穴，史前文化也随之发生了重要改变。影响古人类演化的因素鹅很多，究竟是什么原因驱使古人类离开洞穴，改变生活习性，这一问题一直都是困扰考古学界的难题。本文通赤研究桂北地区洞穴遗址的堆积特点，结合洞穴沉积－堆积物的特征及其孢粉记录的古气候信息，探讨了季风气候变化对桂林地区古气候变化的影响作用和气候演变历史，揭示了桂林地区全新世以来的季风气候变化时间序列和突变事件以及对古人类生存环境的影响。距今7000a 左右为中全新世气候适宜期，东亚夏季风强盛，气温升高，桂林地区的降雨增多，一方面由于地下河水位升高，淹没了穴居洞穴，其次是由于降雨增多，导致洞穴湿度增大，从而迫使古人类搬出洞穴。  相似文献   

形变数字化观测曲线畸变与处理——兼论资料预处理中遇到的一些问题     

黄晓华 《福建地震》2005,(4)

数字化形变台站日常下载、处理直至管理数据,都应用《数字化通讯控制软件》、《形变前兆台站(网)数据处理系统》及《形变前兆数据库服务软件(台站版)》等三个软件交互进行,在实际使用过程中会遇到一些棘手的问题。本文结合我台的观测工作的实践,总结经验,以供台站同行共享。  相似文献   

浅析福建地倾斜潮汐因子γ及其组合动态特征     

傅再扬  危福泉  吴绍祖  陈光 《福建地震》2005,(Z1)

本文计算了福建自1992年至2004年以来的地倾斜EW和NS两分量的固体潮潮汐因子,并进行动态组合,绘制组合动态三种特征量:ΔγEW ΔγNS(表征扩容)、ΔγEW-ΔγNS(表征剪切应变)、ΔγEW/ΔγNS(表征介质各向异性)的时序曲线图,并进行固体潮特征分析,寻找中、强地震发生前远场块体和近场块体地倾斜突变性形变异常与之对应关系。结果表明:在福建沿海,海潮是决定倾斜固体潮特征的主要因素;福建发生5级上的中强地震、台湾发生7级以上强烈地震时,福建地倾斜固体潮潮汐因子及其动态组合特征存在明显的渐进式突变性形变异常现象,异常量和异常持续时间与震级和震中距有较好的对应关系。  相似文献   

Prediction of creep characteristic of rock under varying environment   总被引：2，自引：0，他引：2  

T. N. Singh  A. K. Verma 《Environmental Geology》2005,48(4-5):559-568

The strain developed due to creep is mainly proportional to the logarithm of the time under load, and is mostly proportional to the stress and temperature. At higher temperature the creep rate falls slowly with respect to time, and the creep strain is proportional to a fractional power of time, with the exponent increasing as the temperature increases and reaching a value approximately one-third at temperatures of about 0.5°C. At these temperatures, the creep increases with stress according to a power greater than unity and possibly exponentially. It increases with temperature as (−U/kT), where U is an activation energy and k is Boltzman’s constant. There are different methods to determine the creep strain and the energy of Jog (B) including experimental methods, multivariate regression analysis, and by numerical simulation. These methods are less cumbersome and time consuming. In the present investigation, artificial neural network technique has been used for prediction of the creep strain and energy of Jog (B). Two different networks have been tested and validated. Both the networks have four input neurons and one hidden layer with five neurons, and one output neuron. The data for different rocks at temperatures up to 750°C under conditions of compressive or tortional stress are taken from the literatures. The training and testing data sets used were 163 and 14, respectively. To deal with the problem of overfitting of data, Bayesian regulation has been used and network is trained with suitable training epochs. The coefficients of correlation among the predicted and observed values are found high and they improve the confidence of the users. The mean absolute percentage error obtained are also very low.  相似文献   

Experimental determination of REE partition coefficients between zircon,garnet and melt: a key to understanding high‐T crustal processes          下载免费PDF全文

R. J. M. Taylor  S. L. Harley  R. W. Hinton  S. Elphick  C. Clark  N. M. Kelly 《Journal of Metamorphic Geology》2015,33(3):231-248

The partitioning of rare earth elements (REE) between zircon, garnet and silicate melt was determined using synthetic compositions designed to represent partial melts formed in the lower crust during anatexis. The experiments, performed using internally heated gas pressure vessels at 7 kbar and 900–1000 °C, represent equilibrium partitioning of the middle to heavy REE between zircon and garnet during high‐grade metamorphism in the mid to lower crust. The D_REE (zircon/garnet) values show a clear partitioning signature close to unity from Gd to Lu. Because the light REE have low concentrations in both minerals, values are calculated from strain modelling of the middle to heavy REE experimental data; these results show that zircon is favoured over garnet by up to two orders of magnitude. The resulting general concave‐up shape to the partitioning pattern across the REE reflects the preferential incorporation of middle REE into garnet, with D_Gd (zircon/garnet) ranging from 0.7 to 1.1, D_Ho (zircon/garnet) from 0.4 to 0.7 and D_Lu (zircon/garnet) from 0.6 to 1.3. There is no significant temperature dependence in the zircon–garnet REE partitioning at 7 kbar and 900–1000 °C, suggesting that these values can be applied to the interpretation of zircon–garnet equilibrium and timing relationships in the ultrahigh‐T metamorphism of low‐Ca pelitic and aluminous granulites.  相似文献   

基于GPS速度场的云南地壳应力积累特征分析     

唐红涛  贾鹏  刘芳 《大地测量与地球动力学》2018,38(2):125-128

利用2009~2015年的GPS水平运动速度场数据，解算云南地区的地壳应变场，在红河断裂与曲江断裂选取两个GPS剖面，计算并分析两个断裂的应变积累特征。结果显示：1）红河、曲江、小江等多个主要断裂应变场存在张、压交替的时空演化特征，近期曲江断裂南段表现为东西向拉张，红河断裂北段东西向拉张量值较大，约12.0×10-8/a，云南南部主要表现为NNE向的压性变化；2）从GPS剖面看，红河、曲江断裂在两个方向上均显示右旋走滑与拉张的变化特征，从量值上看，红河断裂北段运动速率较大,约8.90 mm/a。  相似文献