地震CT法隐伏矿脉空间定位研究

利用0．5ms采样的高分辨率地震CT方法对宽度不足1m的隐伏矿脉进行了有效的观测和追踪．本研究不只限于地震CT方法常采用的地表一井孔、井间、坑道等观测方式,而是适当地利用矿田地形实现了近似全方位的地震CT野外数据采集,在本研究提出的非均匀介质射线追踪方法下实现了对隐伏含金石英脉的定量观测．     

Seismic Zoning of Croatia

The territory of Croatia and neighboring regions is divided into 17 seismic source zones, considering available seismological and geological data. On this basis, seismic hazard elements (seismicity rate, maximum magnitude, b-value, probabilities of exceedance and return periods for a predefined set of magnitudes) are computed using the maximum likelihood method appropriate for treating data-sets with variable completeness thresholds. The values of long term expected peak horizontal acceleration obtained by using a combination of the deterministic and the probabilistic procedure are the highest in the Dubrovnik zone, while the Zagreb zone has the highest earthquake hazard in the continental part of the country. This revised version was published online in June 2006 with corrections to the Cover Date.     

Damage response of multistorey r/c buildings with different structural systems subjected to seismic motion of arbitrary orientation

In the present study the combined influence of seismic orientation and a number of parameters characterizing the structural system of Reinforced Concrete (R/C) buildings on the level of expected damages are examined. For the purposes of the above investigation eight medium‐rise buildings are designed on the basis of the current seismic codes. The structural characteristics examined are the ratio of the base shear received by the structural walls, the ratio of horizontal stiffness in two orthogonal directions and the structural eccentricity. Then, the buildings are analyzed by nonlinear time response analysis using 100 bidirectional earthquake ground motions. The two horizontal accelerograms of each ground motion are applied along horizontal orthogonal axes, forming 72 different angles with the structural axes. The structural damage is expressed in terms of the Park and Ang damage index. The results of the analyses revealed that the damage level of the buildings is strongly affected by the incident angle of the ground motion. The extent at which the orientation of the seismic records influences the damage response depends on the structural system and the distance of the record to the fault rupture. As a consequence, the common practice of applying the earthquake records along the structural axes can lead to significant underestimation of structural damage. Also, it was shown that the structural eccentricity can significantly differentiate the seismic damage level, as well as the impact of the earthquake orientation on the structural damage. Copyright © 2015 John Wiley & Sons, Ltd.     

煤田三维地震勘探技术在河流及河漫滩地区的应用

山西高河井田属海河水系长治盆地水文区,主要河流为纵贯全区的浊漳河,自西南流入区内。勘探区内地形地质条件复杂,河流及河漫滩面积大,为克服三维地震勘探存在的诸如检波线的铺设、检波器藕合、激发层位选择等难题,主要采取了陆上检波器挖坑埋置（黄土地段坑深20cm,沙滩地段坑深40cm）、水上检波器用木桩固定等措施,并采用陆上井中放炮、砾石层坑炮、河水中水下放炮相结合的激发方式。为防止井喷和声波产生的高频随机干扰,采取浅井井口压沙袋技术。通过处理解释,获得了较为精确的断层、陷落柱等地质信息,为矿方安全生产提供了可靠的地质保障。     

岩溶探测中井间地震波层析成像的应用

结合在岩溶地区开展的工程勘察实例,运用井间地震波层析成像技术研究钻孔之间的地质剖面.在确定岩溶、裂隙、破碎带的空间位置方面所能解决的程度、适用条件、准确性等方面,表明该技术是一种数字化、高精度的技术方法.     

中朝板块元古宙板内地震带与盆地格局

地史中发生的强地震事件在地层中留下固定的记录 (图 1～ 3) ,这些记录在区域上呈带状分布 ,代表地史中的地震带。中朝板块元古宙目前可识别出两个板内地震带 (图 5 )。中元古代板内地震带 (170 0～ 12 0 0Ma)西起太行山北段 ,经燕山山脉、辽宁西部、穿越辽河平原至辽宁北部的泛河流域分布 ,即燕山—泛河地震带 ,现今呈NEE向延伸。新元古代震旦纪地震带沿吉林南部、辽东半岛、山东中部及苏皖北部现今呈NNE走向分布 ,即古郯庐地震带 (6 5 0～ 6 0 0Ma)。上述两个板内地震带是元古宙不同时期超大陆裂解的响应。中元古代与新元古代两个不同方向的地震断裂带分别控制着两个时期的盆地边界。燕山泛河地震断裂带构成中元古代海盆南界 (指现在的位置 ) ,形成向北开放的海域。古郯庐地震断裂带将中朝板块裂解为华北块体与胶辽朝块体。古郯庐地震断裂带构成震旦纪海域的边界 ,震旦纪海盆通过朝鲜半岛与当时的外海相连接 ,华北块体则为陆源剥蚀区。文内四幅古地理图 (图 6～ 9)是以地震灾变思想为指导 ,以新的地层研究、对比为基础编制的 ,侧重反映了盆地的格局及其变化。根据地震、同沉积断裂新的思路 ,可提供地质学家重新认识与解释某些沉积矿床的成因 ,它们的成矿元素均来自地球深部而非地表风化作用。文中编制     

地震折射波的虚拟射线理论及其应用

本文提出了一种地震折射液的虚拟射线理论,根据该理论,只要已知地表层的速度,即可直接由折射波信息提取地震参数,从而可实现折射界面的反演。 文中通过实际介质模型的计算机实验结果,验证了该理论的正确性。     

新型矿井多波多分量地震反射波观测系统的设计

针对DTC-150防爆地质超前探测仪在工程应用中存在的几个问题,提出了研制新型矿井多波多分量地震反射波观测系统的必要性.通过对大量工程预测预报资料的分析,结合煤岩有效地震波频率特性等4个关键技术的研究,得出了煤岩有效地震波频率范围和观测系统的有效布设方式,研制了高速、高精度、多通道数据采集及处理系统,给出了掌子面绕射回波形成的探测盲区和巷道声波的处理方法,提出了掌子面绕射回波与直达波不重叠的条件.新型矿井多波多分量地震反射波观测系统的研制成功为矿井提供了更为准确、更长距离的超前预测预报手段,同时也为煤矿安全生产提供了有力的保证.     

Strain segmentation and lateral membrane deformation rate of the subducted Ryukyu slab

Abstract Focal mechanisms of intermediate-depth earthquakes within the subducted Ryukyu slab indicate a systematic pattern of down-dip extension in the northern part under Kyushu. These mechanisms switch rapidly around the Tokara channel to down-dip compression in the southern part toward Taiwan. This intriguing pattern of strain segmentation, together with the differences between the slab geometry of the northern and southern parts, has raised the question of whether stress segmentation, as defined possibly by a tear fault, might exist in the slab. However the Ryukyu trench has a concave oceanward shape in the northern segment while it is convex in the southern oceanward part toward Taiwan. The inflection zone is located around the Tokara channel. The concept of Gaussian curvature of a curved surface suggests that the along-arc variation of the geometric configuration of a subducted slab is related to the shape of the trench. This is in order to accommodate the lateral membrane deformation of the slab as the oceanic lithosphere subducts from a spherical shell to the geometry delineated by the Wadati-Benioff zone. The membrane deformation regime of the subducted Ryukyu slab and its relation with the trench geometry was examined by assuming that the subduction be modelled by the flow field of a thin viscous sheet. A projection operator was utilized to compute the membrane strain-rate tensor of an arbitrary non-Euclidean surface. Numerical experiments indicated that the northern segment of the slab was dominated by lateral compression and down-dip extension and the southern part by lateral extension and down-dip compression. This transition is sharply located near the Tokara channel. These patterns were compatible with what had been observed from studies of focal mechanisms, suggesting that the strain segmentation might be controlled, at least in part, by the lateral membrane deformation within the slab due to the trench shape in this subduction zone. The slab geometry was predicted by minimizing the integrated total dissipation power; this revealed distinct features that were consistent with observations. This implies that the slab geometry may also be affected by the membrane deformation in a systematic fashion.     

A study on feasibility of SI for identification of earthquake damages in Taiwan

Using the actual damage data of the strong earthquakes in Taiwan, the effectiveness of the earthquake risk indices, namely, peak ground acceleration (PGA) and spectral intensity (SI), is verified. PGA and Housner's [Housner GW. Spectrum intensity of strong-motion earthquakes. In: Proceedings of symposium on earthquakes and blast effects on structures. EERI, UCLA; 1952] definition of SI are directly compared. A three-parameter spectral intensity system with spectral intensities SI_a, SI_v, and SI_d in the acceleration, velocity, and displacement regions, respectively, is discussed. Here, the effectiveness of SI, SI_a, SI_v, and SI_d has been compared by using the available earthquake-damage data in Taiwan. Three period ranges, namely, 0.1–0.6, 0.6–1.6, and 1.6–3.0 s were used for structures of 1–6 stories, 7–20 stories, and 21 and more stories, respectively. The results indicate that the three-parameter system is a good risk index of the damage potential of earthquakes.