断层滑动速率变化对滑动稳定性的影响

在与主压应力方向斜交的断层上,正应力与剪应力之间存在线性相关关系,以此为基础导出了小扰动条件下决定稳定性的临界刚度与滑动速率的关系。由于这一关系具有临界刚度随滑动速率增加而减小的特点,因此速率增加可能导致周期性粘滑向稳定滑动转化,而速率减小可能使本来稳定的滑动转化为周期性粘滑过程。在这种斜交断层中,速率增加虽然可能抑制周期性粘滑,但是稳滑时超过一定限度的速率增加会导致一次性不稳定滑动。三轴摩擦实验提供了关于粘滑与稳滑可相互转化的支持证据     

天津滨海新区地面沉降层位的精准识别与沉降过程重建

塘沽地区地面沉降是新生代松散沉积物多层位沉降叠加的结果,精准识别各层位的沉降贡献是该区地面沉降防控的关键。利用塘沽G2地面沉降分层标组2011—2014年观测数据,对新生代沉积物不同层位的地面沉降进行了精准识别;结合以前的分层标观测资料,重建了1960年以来不同层位的地面沉降过程。结果显示,在1960—1970年地下水开发初期,地面沉降主要层位是浅部粘性土自然固结和第二含水组地下水开采;1970—1980年深层地下水开采高峰期,主沉降层位由二组逐渐加深到三、四组;1985年以后实施了地面沉降控制措施后,第四系地下水开采引起的地面沉降逐渐减小;2000年之后,随着滨海新区的成立和大规模的城市建设,城市建设引起的建筑基础沉降逐渐成为主要的沉降层。通过对不同时期主要地面沉降层位的转换过程分析,提出地面沉降精准防治新思路。     

高温高压条件下辉长岩的摩擦强度和滑动稳定性

过去的变形实验表明,花岗质岩石变形的主要控制因素是高温下易于变形的石英.然而随着深度的增加,石英含量逐步减少到对变形来说无足轻重的地位,岩性则从中地壳下部的中性向下地壳的基性过渡.在摩擦本构参数研究中,以往的研究主要将注意力放在了中上地壳典型的花岗质岩石上(Lockner等,1986;Blanpied等,1995),而对于其下部的中性岩和基性岩则涉及甚少.在早期,Stesky等(1974)对Marcos gabbro进行了初步研究,但是当时未涉及速度依赖性问题,因此,其结果不能用于滑动的稳定性分析.     

Upper Limit for Rheological Strength of Crust in Continental Subduction Zone： Constraints Imposed by Laboratory Experiments

The transitional pressure of quartz-coesite under the differential stress and highly-strained conditions is far from the pressure of the stable field under the static pressure. Therefore, the effect of the differential stress should be considered when the depth of petrogenesis is estimated about ultrahigh pressure metamorphic (UHPM) rocks. The rheological strength of typical ultrahigh pressure rocks in continental subduction zone was derived from the results of the laboratory experiments. The results indicate the following three points. (1) The rheological strength of gabbro, similar to that of eclogite, is smaller than that of clinopyroxenite on the same condition. (2) The calculated strength of rocks (gabbro, eclogite and clinopyroxenite) related to UHPM decreases by nearly one order of magnitude with the temperature rising by 100 ℃ in the range between 600 and 900 ℃. The calculated strength is far greater than the faulting strength of rocks at 600 ℃, and is in several hundred to more than one thousand mega-pascals at 700-800 ℃, which suggests that those rocks are located in the brittle deformation region at 600 ℃, but are in the semi-brittle to plastic deformation region at 700-800 ℃. Obviously, the 700 ℃ is a brittle-plastic transition boundary. (3) The calculated rheological strength in the localized deformation zone on a higher strain rate condition (1.6×10-12 s-l) is 2-5 times more than that in the distributed deformation zone on a lower strain rate condition (1.6×10-14 s-1). The average rheological stress (1 600 MPa) at the strain rate of 10-12 s-1 stands for the ultimate differential stress of UHPM rocks in the semi-brittle flow field, and the average rheological stress (550-950 MPa) at the strain rate of l0-14 -10-13 s-l stands for the ultimate differential stress of UHPM rocks in the plastic flow field, suggesting that the depth for the formation of UHPM rocks is more than 20-60 km below the depth estimated under static pressure condition due to the effect of the differential stress.     

松花江水体总汞与甲基汞污染特征的研究

研究了松花江吉林市至三岔河口江段水体总汞与甲基汞污染特征。结果表明，随着主要工业汞与甲基汞污染源的治理和根治，该江段江水、表层沉积物和鱼类的总汞与甲基汞污染水平逐年下降，目前已基本降到轻度污染水平，而且各江段之间和年际间的差异已不显著，说明该汞源对江段水体的影响越来越小，目前对该江段（鱼和水）汞污染影响较大的是沉积汞。     

岩石摩擦弱化及失稳序列的数值模拟

通过基于“瞬间闭锁”假定的多滑块-弹簧模型对摩擦滑动进行模拟,讨论了强度分布不均匀性及系统刚度构成对整个系统稳定性的影响.通过图示平均剪应力和平均位移的关系,对断层模型随错动的演化作了清晰的描述.结果表明:(1)均匀的滑动面及外部系统刚度较小的情况(这相当于高压条件下形成的光滑剪切破裂面的情况)易于发生粘-滑振荡.(2)随着错动次数的不断增加,错动的空间分布向不均匀方向发展,从而使平均应力降减小,系统整体趋向稳定,即断层活动历史越长越趋向稳定.(3)由于导入了具有负刚度效果的力和位移组合控制,通常加载方式条件下只能产生不稳定的过程可以转变为一个平均效果上的准静态弱化过程,类似于滑动弱化过程.     

用高温高压岩石蠕变实验解释岩石圈流变时存在的若干问题的讨论

由于实验条件和实际地质条件的差别,在实验温压条件下得出的变形机制。流动律和微观组构不等同于岩石圈相同温压条件下的变形机制、流动律和微观组构。因此,用高温高压蠕变实验结果直接外推解释岩石圈流变时存在若干问题。只有把实验条件、变形机制、微观组构作为一个有机的整体。去理解和认识岩石圈流变特性,才不至于产生太大的偏差。     

A fast automatic identification method for seismic belts based on distance correlation and its earthquake case*

Earthquake prediction practice and a large number of earthquake cases show that anomalous images of small earthquake belts may appear near the epicenter before strong earthquakes. Through the research of earthquake cases, researchers have a relatively consistent method to determine the clarity of an identified seismic belt, but there is still a lack of method on seismic belt identification from the distribution of scattered points. Due to the complexity of exhaustive algorithm, the rapid automatic identification technique of seismic belts has been progressing slowly. Visual recognition is still the basic method of seismic belt identification. Based on the algorithm of distance correlation, this paper presents a fast automatic identification method of seismic belts. The effectiveness of this method was proved by 100 random earthquakes and an example of seismic belts of magnitude 4.0 before the 2005 Jiujiang M5.7 earthquake. The results show that: ① the automatic identification of seismic belts should first identify the “relational earthquake”, then identify the “suspected seismic belt”, and finally use the criterion of seismic belt clarity to determine; ② random earthquakes and real earthquakes identification results show that the distance correlation method can realize the fast automatic identification of seismic belts by computer.     

GIS专业面向对象程序设计教学改革探讨

面向对象程序设计课程在GIS专业教学体系中具有十分重要的地位。针对该课程在教学和实践中存在的问题,结合多年的教学经验,从教学内容、教学方法、教学手段以及实践教学等方面进行了改革探讨,以期能更好地实现本课程的教学目标,提高教学效果。     

水系沉积物测量发现新疆乌恰县吾合沙鲁中型铜矿

正1研究目的(Objective)新疆乌恰县吾合沙鲁地区位于塔里木盆地西缘,区域上发育重要的砂砾岩型铜铅锌-天青石-铀-煤成矿系统,已分布有乌拉根超大型砂砾岩型铅锌矿、萨热克大型砂砾岩型铜矿、萨哈尔铜矿、花园铜矿、杨叶铜矿、杨树沟铜矿、吾东—伊日库勒铜矿等典型矿床,具有十分独特的砂砾岩型铜铅锌矿