南湾水库坝基渗透监测分析与稳定性研究

南湾水库坝基存在顺河断层,查明断层的结构、颗粒组成、透水性及允许渗透比降,判断其可能发生的渗流破坏形式是南湾水库除险加固工程的一个重点和难点。由于现场钻孔管涌试验所得的坝基岩体试验破坏坡降较大,不足以反映断层破碎带最差部位的岩体破坏坡降。在详细分析了南湾水库坝基顺河断层的工程地质条件和水文地质条件后,对坝体和坝基的长期渗透观测资料进行分析,并对坝址区顺河断层带进行渗透稳定性研究,结果表明坝体和坝基的渗透稳定,发生渗透破坏可能性较小。     

从水系的分布形态探讨沂沭断裂带的运动特征

郯城-庐江断裂带是纵贯中国大陆东部,长达2 000 km以上的大断裂带。该研究利用DEM数据和ETM,以及谷歌卫星影像来分析郯城-庐江断裂带中段的沂沭断裂带周边的水系的几何分布形态特征。三维卫星图像解译和野外调查的结果显示：(1)沿断裂带周边发育的水系的几何分布形态主要受由F1-F4 4条主要断层所组成的沂沭断裂带构造所制约;(2)沿断裂带发育的水系不具有典型的走滑断层的系统化的同步转折和位错的变形特征;(3)沂沭断裂带东侧的F1和F2断裂是现今的活动断裂,而F3和F4断裂在第四纪基本没有明显的活动迹象;(4)F1和F2断裂以垂向运动为主,具有高角度的逆断层或正断层的运动特征。该研究结果显示沿断裂发育的水系地貌和几何分布特征可作为评价断裂的活动性和运动特征的地貌标志。     

K–Ar illite dating to constrain multiple events in shallow crustal rocks: Implications for the Late Phanerozoic evolution of NE Asia

A recently developed illite-age-analysis (IAA) approach was applied to determine the multiple events for the Chugaryeong fault belt, Korea. Each event was determined by a combined approach of the optimized illite-polytype quantification and the K–Ar age-dating of clay fractions separated from the fault clays. The Late Cretaceous to Paleogene events (76.5 ± 0.8, 69.1 ± 0.6, 59.3 ± 0.7, and 48.2 ± 0.7 Ma) were recognized by calculating the authigenic 1M/1M_d illite ages on the IAA plots of the fault clays. The Early Cretaceous ages (121.7–124.7 and 112.4 ± 1.5 Ma) were also obtained from the convergent intercepts of 100% 2M₁ illite on the IAA plots. The absence of the 2M₁ illites in the host-rock indicates that the Early Cretaceous ages represent the timings of high-T hydrothermal events of >280 °C. The 2M₁ illites in the fault clays should be pre-formed by a fluid-rock interaction under a relatively high-T subsurface condition, and be mechanically reworked into the near surface along the fault by post-tectonic events. This is the first report determining the absolute age constraints of multi-activated tectonic events from a fault. These geochronological determinations of the multiple events recorded in the Chugaryeong fault belt are crucial to establish the tectonic evolution of the Korean Peninsula since the Late Cretaceous.     

Formation and development of normal-fault calderas and the initiation of large explosive eruptions

The ring fractures that form most collapse calderas are steeply inward-dipping shear fractures, i.e., normal faults. At the surface of the volcano within which the caldera fault forms, the tensile and shear stresses that generate the normal-fault caldera must peak at a certain radial distance from the surface point above the center of the source magma chamber of the volcano. Numerical results indicate that normal-fault calderas may initiate as a result of doming of an area containing a shallow sill-like magma chamber, provided that the area of doming is much larger than the cross-sectional area of the chamber and that the internal excess pressure in the chamber is smaller than that responsible for doming. This model is supported by the observation that many caldera collapses are preceded by a long period of doming over an area much larger than that of the subsequently formed caldera. When the caldera fault does not slip, eruptions from calderas are normally small. Nearly all large explosive eruptions, however, are associated with slip on caldera faults. During dip slip on, and doming of, a normal-fault caldera, the vertical stress on part of the underlying chamber suddenly decreases. This may lead to explosive bubble growth in this part of the magma chamber, provided its magma is gas rich. This bubble growth can generate an excess fluid pressure that is sufficiently high to drive a large fraction of the magma out of the chamber during an explosive eruption. Received: 2 January 1997 / Accepted: 22 April 1998     

基于时频分析的裂纹转子碰摩故障特征研究

为研究转子系统耦合故障特性,采用有限元方法建立了含有横向裂纹、转静碰摩的非线性转子动力学模型。首先研究了不同转速下裂纹、碰摩单一故障下转子系统的振动响应,其次研究了两种故障耦合情况下系统的振动响应特征。采用波形图、FFT谱图、瞬时频率和Hilbert-Huang时频谱(HHS)相结合的方法对故障转子振动信号进行了分析。分析结果表明:运用多种时频分析相结合的方法可以较为全面地了解转子的故障特征,裂纹转子在1/5、1/3临界转速时会发生较为明显的5X、3X谐波,且裂纹的产生会导致响应幅值增大,从而引起更为严重的碰摩。      

2005年会泽5.3级地震与小江断裂地震活动关系研究

根据小江断裂带历史强震资料、近期中小地震活动资料、地震波参数、会泽5．3级地震破裂方向及其序列参数显著异常等,研究了小江断裂带强震活动规律、中强地震丛集活动与断裂构造活动关系、会泽地震后小江断裂及周围地区应力场状态,结果得出：①会泽周围M≥5．0地震丛集活动达10次左右后,小江断裂及周围地区将发生M≥6．7地震;②会泽地震发生后,其附近3级以上中小地震活动空间展布方向与小江断裂北东向深部隐伏次级断裂的方向一致;③会泽地震发生后,其附近中小地震波参数规一化环境剪应力‰值与本次地震序列参数b值异常显著;④会泽地震余震震源较深,90％可测定深度的余震震源深度在16～30km范围内,比震前震源区周围的地震深。     

不同类型地震的地震矩-震级标度关系研究

收集整理了中国大陆1977～2001年发生的107次M≥5．0地震的震型、震源机制、发震断层、地震矩等参数，在此基础上研究了不同震型、不同断层性质地震的地震矩与震级的关系。结果表明，地震矩和震级标度关系中直线的斜率与地震视应力和介质非均匀程度相联系，走滑断层地震的视应力和介质的非均匀程度均高于非走滑断层地震，走滑断层中孤立型地震的视应力和介质的非均匀程度均低干多震型地震。     

王府断陷断裂特征及其对深层火山岩气藏的控制作用研究

松辽盆地深层火山岩天然气藏勘探获突破进展,表明火山岩成藏条件良好。在火山岩天然气成藏研究方面前人做了很多工作,但对于断层在成藏控制作用方面研究较少。本文以松辽盆地东南部王府断陷为研究对象,利用地震资料进行构造、断裂精细解释,总结了断裂发育特征,并系统分析了断裂体系对成藏的控制作用,认为该区断裂体系是火山岩气藏最为根本和关键的控制因素,具体表现在不同级别、不同期次的断层对油气成藏的控制作用不同。王府西断裂为铲式断裂,是控制洼陷形成的边界大断层。王府1东基底断裂与城深2东基底断裂控制了山东屯与小城子两个二级构造带的形成,还直接控制火山岩储集体的分布。本区火山口大多发育于两条或多条断裂的交汇处,其四周依次发育爆发相、溢流相、火山通道相、火山沉积相,其中最有利的火山岩储集体主要发育于爆发相与溢流相。利用地震技术能够对火山岩储集体进行有效识别。储层研究表明,山东屯构造带火山岩储集体发育,西邻沉积中心与烃源岩构成良好的生储盖组合,是王府断陷深层天然气成藏最为有利的地区。断裂体系对火山口与火山岩相及储集体的分布具有重要的控制作用,对研究区火山岩成藏至关重要。这些认识对类似地区的勘探有一定指导作用。     

利用GPS和水准数据分析东昆仑断裂带东部及其邻区构造变形特征

基于1999—2016年GPS数据和1980—2010年区域精密水准数据,获取了东昆仑断裂带东部及其邻区主要断裂的滑动速率和区域构造变形特征。结果表示:东昆仑断裂带自西向东的走滑速率衰减非常明显,走滑速率从西大滩—东大滩和阿拉克湖段的约10 mm/a向东到塔藏段衰减至约2 mm/a,速率自西向东每100 km下降梯度约1 mm/a;东昆仑断裂带阿拉克湖段、托索湖段、下大武段和塔藏段均表现出一定的弱挤压特征。跨岷江断裂剖面显示区域挤压变形自西向东由龙日坝断裂至龙门山断裂带有逐渐减弱的特征。区域最大主应变方向为E-NEE向,最大剪切应变高值区位于阿拉克湖段和托索湖段交汇区域以及巴颜喀拉块体的龙日坝断裂中段区域。分析东昆仑断裂带东部及其邻区主要断裂间的构造转换关系认为,岷山地区的隆起变形主要是因为巴颜喀拉块体自西向东的运动受到了华南块体的阻挡,而非东昆仑断裂带向东延展引起的构造转换。