边坡模型边界效应及材料孔隙率敏感性研究

通过自制的新型试验装置进行不同边界情况下的边坡模型变形破坏研究。探讨了边坡模型破坏开始时的坡角（破坏角）与边界条件的关系。试验结果表明,该破坏角会与模型厚度成一定的反比关系,但随着模型厚度超过一定值,边界条件造成的影响将趋于弱化,同时,运用数学手段定量地印证了这种关系形式。另外,还通过试验验证了相比于边界条件而言,破坏角的变化幅度会对模型材料的孔隙率更加敏感。基于所得结果,可对试验装置进行改进,并优化试验手段。     

The mean and turbulence structure simulation of the monsoon trough boundary layer using a one-dimensional model withe-l ande-ε closures

An attempt has been made here to study the sensitivity of the mean and the turbulence structure of the monsoon trough boundary layer to the choice of the constants in the dissipation equation for two stations Delhi and Calcutta, using one-dimensional atmospheric boundary layer model withe-ε turbulence closure. An analytical discussion of the problems associated with the constants of the dissipation equation is presented. It is shown here that the choice of the constants in the dissipation equation is quite crucial and the turbulence structure is very sensitive to these constants. The modification of the dissipation equation adopted by earlier studies, that is, approximating the Tke generation (due to shear and buoyancy production) in theε-equation by max (shear production, shear + buoyancy production), can be avoided by a suitable choice of the constants suggested here. The observed turbulence structure is better simulated with these constants. The turbulence structure simulation with the constants recommended by Aupoixet al (1989) (which are interactive in time) for the monsoon region is shown to be qualitatively similar to the simulation obtained with the constants suggested here, thus implying that no universal constants exist to regulate dissipation rate. Simulations of the mean structure show little sensitivity to the type of the closure parameterization betweene-l ande-ε closures. However the turbulence structure simulation withe-ε. closure is far better compared to thee-l model simulations. The model simulations of temperature profiles compare quite well with the observations whenever the boundary layer is well mixed (neutral) or unstable. However the models are not able to simulate the nocturnal boundary layer (stable) temperature profiles. Moisture profiles are simulated reasonably better. With one-dimensional models, capturing observed wind variations is not up to the mark.     

嵌入式时间间隔计数器的研制

介绍了一种新研制的嵌入式时间间隔计数器，它可作为一种功能模块用于用户的设备或时统中，实现高精度时间测量。从基本原理、硬、软件和功能等不同角度对计数器进行了较为详细的讨论。在该计数器的研制过程中还开发了用来调试计数器和供计数器用户使用的计算机应用软件，对此也作了简要介绍。最后，给出了计数器的设计指标和一些实测数据。     

分潮波模型多资料数值计算方法研究 Ⅰ.岸边资料运动学外推的第一边值方法

对于含多资料三维分潮波模型建立了一种岸边资料运动学外推的潮波第一边值方法，并对渤海的四大原湖波进行试算。结果证实本方法可行，该方法使潮波方程既满足第一边值问题，充分利用岸边测站资料，又保证岸界法向流速为零条件，符合物理意义。并对复型病态矩阵的收敛问题提出了一种可行性处理。     

Uniform half-plane elastodynamic problems by an approximate boundary element method

In this paper the applicability of an approximate Boundary Element Method to uniform half-plane elastodynamic problems is investigated. This method employs the concept of images to construct approximate fundamental solutions for the half-plane and does not require any half-plane surface discretization. The method is formulated in the frequency domain for the case of harmonic disturbances or the Laplace transform domain for the case of transient disturbances. In the latter case a numerical inversion of the transformed solution is necessary to obtain the time domain response. The proposed method can be used as an alternative to boundary element methods that either utilize the infinite plane fundamental solution and thus require a half-plane surface discretization, or employ the exact half-plane fundamental solution, which even though leads to no surface discretization, is of a very lengthy and complicated form. Two characteristics numerical examples are used to illustrate the proposed method and study its advantages and disadvantages.     

Rifting to Spreading Process along the Northern Continental Margin of the South China Sea

Understanding the development from syn-rift to spreading in the South China Sea (SCS) is important in elucidating the western Pacific's tectonic evolution because the SCS is a major tectonic constituent of the many marginal seas in the region. This paper describes research examining the transition from rifting to spreading along the northern margin of the SCS, made possible by the amalgamation of newly acquired and existing geophysical data. The northernmost SCS was surveyed as part of a joint Japan-China cooperative project (JCCP) in two phases in 1993 and 1994. The purpose of the investigation was to reveal seismic and magnetic characteristics of the transitional zone between continental crust and the abyssal basin. Compilation of marine gravity and geomagnetic data of the South China Sea clarify structural characteristics of its rifted continental and convergent margins, both past and present. Total and three component magnetic data clearly indicate the magnetic lineations of the oceanic basin and the magnetic characteristics of its varied margins. The analyses of magnetic, gravity and seismic data and other geophysical and geological information from the SCS led up to the following results: (1) N-S direction seafloor spreading started from early Eocene. There were at least four separate evolutional stages. Directions and rates of the spreading are fluctuating and unstable and spreading continued from 32 to 17 Ma. (2) The apparent difference in the present tectonism of the eastern and western parts of Continent Ocean Boundary (COB) implies that in the east of the continental breakup is governed by a strike slip faulting. (3) The seismic high velocity layer in the lower crust seems to be underplated beneath the stretched continental crust. (4) Magnetic anomaly of the continental margin area seems to be rooted in the uppermost sediment and upper part of lower crust based on the tertiary volcanism. (5) Magnetic quiet zone (MQZ) anomaly in the continental margin area coincides with COB. (6) The non-magnetic or very weakly magnetized layer is probably responsible for MQZ. One of the causes of demagnetization of the layer is due to hydrothermal alteration while high temperature mantle materials being underplated. Another explanation is that horizontal sequences of basalt each with flip-flop magnetization polarity cancel out to the resultant magnetic field on the surface. We are currently developing a synthetic database system containing datasets of seismicity, potential field data, crustal and thermal structures, and other geophysical data to facilitate the study of past, contemporary and future changes in the deep sea environment around Japan; i.e. trench, trough, subduction zones, marginal basins and island arcs. Several special characteristics are an object-oriented approach to the collection and multi-faceted studies of global data from a variety of sources.     

Geodynamic Evolution of the Eastern Segment of the Azores-Gibraltar Zone: The Gorringe Bank and the Gulf of Cadiz Region

Detailed structural interpretation of the recently acquired deep seismic multichannel profiles along the Iberian Atlantic Margins (IAM Project) provides new results on the geodynamic evolution of the eastern part of the Azores-Gibraltar plate boundary. Thrusting and folding of the oceanic basement and of Mesozoic and Cenozoic sedimentary cover of the Gorringe Bank region are consistent with the N–S convergence of Iberia and Africa. Compressive structures in the Gorringe Bank region are spread over a wide area. Deformation under compression took place mainly in Tertiary times, as is evidenced by a basal unconformity and several discontinuities in Tertiary sediments, although some deformation has also been recorded in Quaternary sediments. The compressive structures in the Gulf of Cadiz are E–W oriented thrusts, folds and related diapiric structures. N–S oriented transpressive deformation is likely to occur in the western Portuguese platform. There is no continuity of structures from the oceanic to the continental domain, suggesting that deformation transfers from one side to the other through a transcurrent fault zone. The fault contact between the two domains is located in the ocean-continent transition zone.     

西边界流在边界“豁口”的形变及其机制

大洋西边界流在边界豁口处由于失去边界的支持而发生形变。本文将西边界流视为一种惯性射流，遵循绝对涡度守恒原理，推导了流轴及其两侧流体在西边界豁口处不同形式的弯曲，发现在一定的豁口尺度条件下，西边界流自身的相对涡度分布特点和地球旋转的β效应决定了在失去西侧陆坡支持时，其主体会沿反气旋路径发生一段经向的位移而圈回入射点所在的经度位置。主轴变形的经向尺度与初始速度及西边界流的入射角度有关；主轴西侧可能会出现一小部分分支进入邻近的内海并形成气旋或反气旋式环流；主轴东侧的流体则在豁口以东沿反气旋路径弯曲，从而论证了西边界豁口处形成西边界流弯曲的可能性和原因     

Seismic lamination and anisotropy of the Lower Continental Crust

Seismic lamination in the lower crust associated with marked anisotropy has been observed at various locations. Three of these locations were investigated by specially designed experiments in the near vertical and in the wide-angle range, that is the Urach and the Black Forrest area, both belonging to the Moldanubian, a collapsed Variscan terrane in southern Germany, and in the Donbas Basin, a rift inside the East European (Ukrainian) craton. In these three cases, a firm relationship between lower crust seismic lamination and anisotropy is found. There are more cases of lower-crustal lamination and anisotropy, e.g. from the Basin and Range province (western US) and from central Tibet, not revealed by seismic wide-angle measurements, but by teleseismic receiver function studies with a P–S conversion at the Moho. Other cases of lamination and anisotropy are from exhumed lower crustal rocks in Calabria (southern Italy), and Val Sesia and Val Strona (Ivrea area, Northern Italy). We demonstrate that rocks in the lower continental crust, apart from differing in composition, differ from the upper mantle both in terms of seismic lamination (observed in the near-vertical range) and in the type of anisotropy. Compared to upper mantle rocks exhibiting mainly orthorhombic symmetry, the symmetry of the rocks constituting the lower crust is either axial or orthorhombic and basically a result of preferred crystallographic orientation of major minerals (biotite, muscovite, hornblende). We argue that the generation of seismic lamination and anisotropy in the lower crust is a consequence of the same tectonic process, that is, ductile deformation in a warm and low-viscosity lower crust. This process takes place preferably in areas of extension. Heterogeneous rock units are formed that are generally felsic in composition, but that contain intercalations of mafic intrusions. The latter have acted as heat sources and provide the necessary seismic impedance contrasts. The observed seismic anisotropy is attributed to lattice preferred orientation (LPO) of major minerals, in particular of mica and hornblende, but also of olivine. A transversely isotropic symmetry system, such as expected for sub-horizontal layering, is found in only half of the field studies. Azimuthal anisotropy is encountered in the rest of the cases. This indicates differences in the horizontal components of tectonic strain, which finally give rise to differences in the evolution of the rock fabric.     

华南伊迪卡拉(震旦)系顶部建阶层型和界线层型新资料

新元古代与寒武纪之交,即伊迪卡拉纪—寒武纪过渡期,是地球历史上一个重大的地质突变期,出现了一系列地质环境变化事件和生物快速演化事件。云南东部位于扬子地区西南缘,在前寒武纪—寒武纪过渡期属于开放式浅水台地至台缘斜坡环境,是中国伊迪卡拉(震旦)系顶部与底寒武统基本连续沉积的典型地区,也曾是中国震旦系与寒武系界线层型候选剖面所在地。近年来,在此新发现了更为丰富的宏体藻类化石、遗迹化石和伊迪卡拉生物群的疑似后生动物化石等(江川生物群),以及大量以条带状Shaanxilithes为代表的宏体化石层。相关剖面自下而上从灯影组至磷矿沉积层(中谊村段)出露有连续的宏体化石记录,研究后可以细分伊迪卡拉系顶部灯影峡阶的化石带,并与底寒武统晋宁阶、梅树村阶对接,具有作为标准层型剖面的较大潜力,为伊迪卡拉纪末期年代地层单位的建阶分层、对比及确立层型剖面,以及与寒武纪最早期年代地层的界线划分提供了更为理想的标准。