Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning

The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure and high temperature. The laws of velocity changes for them differ with the pressure boost and temperature rise, and the velocity change of S-type is more violent than that of I-type. The “softening point” of compressional wave velocity (V μ) is also revealed during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth of “softening”, V_p after “softening” and the percentage of V_p’s drop around the “sofrening point” for two types of granitoids are obviously different. The depth of “softening” is 15 km approximately and V_p after “softening” is 5.62 km/s for S-type granitoid. But for I-type granitoid the depth of “softening” is 26 km approximately and V_p after “softening” is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the “softening” of elastic-wave velocity is caused by the partial melting of granite. Combined with the results of geophysical prospecting, these results suggest that the low-velocity layers developing in the interior of Earth crust are related to thc partial melting of different types of granitoids. The formation of the low-velocity layer in the upper-middle Earth crust is closely related to the development of S-type granitoid, but that in the lower Earth crust is closely related to the development of I-type granitoid.     

三维分块倾斜界面的反演及其应用

介绍了利用反射波走时反演介质层速度和包含直立断层的三维界面的计算方法．对各层界面利用多个倾斜或平界面方程来描述．给出了数值计算实例．结果表明，反演解与真模型很接近，说明计算方法是有效的．利用该方法处理了唐山地震区的ＰｍＰ反射波资料，获得了该区域莫霍界面的三维分块形态．唐山附近莫霍界面错断与该区域１９７６年唐山地震及一系列余震的发生有密切的联系．     

关于大陆与陆缘的深部地震探查的进展──1994、1996年两届国际学术讨论会综述

连续两届国际深部地震讨论会成果累累。对深部地震的资料采集、处理、解释技术以及几类专门地质地球物理问题的研究进行了综述。研究成果在理论、方法方面是该领域的世界先进水平：在地震学应用于陆缘、陆壳与壳幔过渡带等地质问题方面有明显的提高。提出了值得讨论的问题，最后探讨了发展趋势     

地球演化中最大的两级节律

地球演化中表现出的最大两级节律为１０×１０８ａ和２×１０８ａ。每２个相邻节律可合并为一个周期，因而地球演化的最大两级周期为２０×１０８ａ和４×１０８ａ。岩石学、地层学和构造地质学方面诸多证据都说明这种划分的合理性。对于地球演化中的这类大型节律及周期性的成因机制，用笔者已提出的“地球多级驻波脉动理论模型”可以得到较合理的解释。     

山西临汾中心地震台地倾斜震前异常变化特征

从原始记录和分量图两方面对山西临汾中心地震台1991年以来的倾斜资料进行了分析，研究了临汾中心地震台地倾斜与省内及周边地区发生的中强地震的关系。结果表明，对1996年至2002年内发生的几次中强地震，临汾中心地震台地倾斜资料都有较好的异常反映。     

用远震接收函数研究滇西地区的深部结构

滇西地区地处欧亚板块碰撞或俯冲的边界地带，曾受到多期构造运动的影响，其地质环境和构造背景十分复杂，是我国地震活动比较活跃的地区之一. 本文选用国家、地方和流动数字台网的16个台站的远震记录. 其中PASSCAL甚宽频带流动地震台站4个，提取有效接收函数近2 000条. 两条测线的直线距离分别为650 km和450 km， 横切了滇西地区的一些主要构造单元. 研究表明，怒江断裂可能是一条具有俯冲性质的缝合线. 川滇菱形块体东西两侧的分界线¾红河断裂和小江断裂可能是直立的缝合线或碰撞带. 攀西构造带仍具有大陆裂谷的特征，即地表凹陷、上地幔隆起. 滇西地区的构造格局具有一定的规律性，造山带与缝合线相间分布. 滇西地区由北向南地壳厚度渐次减薄，S波速度整体偏低.      

岩质高边坡岩体变形参数及松弛带厚度研究

预测岩质高边坡开挖后岩体变形模量的变化及松弛带厚度，是分析岩质高边坡在开挖后变形（位移）和作好防护设计的重要资料，运用波动力学关于平均应力与体积模量、岩体纵波速度与弹性模量、变形模量间的关系，通过部分实测资料及边坡应力场有限元分析的资料，分别建立了纵波速度与岩体变形模、岩体应力间的关系，研究了开挖边坡岩体变形模量的变化，预测了岩体松弛带的厚度。     

A new method of testing pile using dynamic P-S-curve made by amplitude of wave train

A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P(Q)-S curve. Foundation item: Key projects of the tenth Five-year Plan of Yunnan Province (documented Yunnan district [2002]54-02-02) and Geophysical Society of Yunnan Province.     

Geometric form of Haiyuan fault zone in the crustal interior and dynamics implications

The deep seismic reflection data on profile HY2 are reprocessed by the method of simultaneous inversion of velocity distribution and interface position. By the travel-time inversion with the data of the diving wave Pg and fault plane reflection wave, we determine the geometric form and velocity of Haiyuan fault zone interior and surrounding rock down to 10 km depth. The measured data show that the amplitudes have strong attenuation in the range of stake number 37–39 km, suggesting the fault zone has considerable width in the crustal interior. The results of this paper indicate that to the north of the fault zone the crystalline basement interface upheaves gradually from southwest to northeast and becomes shallow gradually towards northeast, and that to the south of the fault zone, within the basin between Xihua and Nanhua mountains, the folded basement becomes shallow gradually towards southwest. The obliquity of the fault zone is about 70° above the 3 km depth, about 60° in the range of the 3–10 km depths. From the results of this paper and other various citations, we believe that Haiyuan fault zone is in steep state from the Earth’s surface to the depth of 10 km. Foundation item: Joint Seismological Science Foundation of China (201001) and State Key Basic Research Development and Programming Project (95-13-02-02). Contribution No. RCEG200308, Exploration Geophysical Center, China Earthquake Administration.     

Field vibration mitigation by honeycomb WIB for pile foundations of a high-speed train viaduct

Environmental vibrations from recent high-speed trains are becoming a special concern in the civil and environmental engineering field since they can give detrimental effects to residents, sensitive equipments and high-tech production facilities in the vicinity of train tacks. Herein, aiming at the vibration mitigation for a specific high-tech industrial area, the low-frequency vibrations from a train viaduct are targeted over an anticipated range. A theoretically designed innovative countermeasure, called honeycomb wave impeding barrier (WIB) for a wave impeding barrier, is introduced and its effects are investigated by computer simulation. The present WIB is based on the wave dispersion phenomenon that can modulate the incoming wavelengths into the shorter wavelengths, creating an apparent wave cut-off characteristic in the wave field across WIB installation area. The shorter wavelengths are further impeded due to the impedance ratio of the WIB walls and in-fill materials and absorbed by the in-fills more. The three-dimensional FEM simulation demonstrates a dramatic reduction effect that is difficult to achieve by conventional measures.