模拟构造型式的新技术

本文介绍一种模拟构造型式的新技术——全息术,着重讨论了用全息干涉测量的技术模拟褶皱构造的方法和原理,并通过雁行式、涡轮状和歹字型褶皱构造的模拟,说明全息术在模拟地质构造中的应用。     

The new approach to global deep sounding

The new approach to global geomagnetic sounding is developed to overcome difficulties of spherical harmonical analysis and subsequent transfer function determination. The approach is based on minimizing the discrepancy between experimental and simulated magnetic fields. The discrepancy is considered as a function of the medium model parameters and the coefficients of external fields. The method can be used for laterally inhomogeneous as well as homogeneous earth models. An example of its application to a radially symmetric model is demonstrated.     

Long- and middle-term behaviour of the tilt and strain variations in the decade following the 1976 friuli earthquake in NE Italy

Tilt and strainmeter data collected in the Friuli seismic area between 1977 and 1985 have been analyzed to study the stress-strain field and/or the elastic parameter variations in the area after the strong 1976 seismic event.We concentrated on three different frequency bands, respectively linked with the tidal waves, the seasonal effect and the secular one. The results from the first two bands point at an increase of the local rigidity modulus.Relevant stresses induced by the seasonal groundwater level variations have been found, thus supporting the hypothesis that they can act as triggering effects. The secular trend reveals significant tectonic stress modifications. It appears that the post-seismic tectonic stresses faded during 1981–1983, and were followed by a new loading phase.On leave from the Institute of Geodesy and Geophysics of the Chinese Academy of Sciences. Ph. D. student at the Institute of Geodesy and Geophysics, Trieste University.     

Large-scale floodplain modelling

A two-dimensional horizontal finite element numerical model (RMA-2) was applied to a 24 km river channel-floodplain reach in West Germany. Initial results indicate that finite element schemes may successfully estimate inundation in large-scale floodplain applications. Potentially, the resulting detailed velocity vector distributions and identification of inundation zones throughout storm events could provide an insight into the present day sedimentary environment on the floodplain.     

被动椭圆形标志物应变分析的计算机模拟

本文采用计算机数学模拟的方法更深入地探讨了椭圆形标志物应变分析技术(R_f/Φ去应变法、Shimamoto等提出的代数法、调和平均值法和算术平均值法)的适用条件。一共形成了十一组有代表性的应变前数组,四种变形路径:纯剪、单剪、纯剪加单剪和体变。当应变前数组在(-90°,90°)内均匀分布或随机分布时,无论变形路径是哪一种(共轴的还是非共轴的),上述的所有方法都是适用有,且以代数法最佳。当应变前数组具有优选方位(单峰分布)且变形路径为共轴递进变形时,在一定条件下,R_f/Φ法能用来估计应变。经分析发现当应变足够大时,调和平均值法是一种简单快速的应变计算法。     

模拟GPS精密测量系统误差的若干问题

讨论了模拟ＧＰＳ精密测量系统误差的一些主要问题．文中用了两个实例，一个是南美洲某油田地面沉陷监测网，另一个是美国超级超导对撞机ＧＰＳ地面控制网．     

A numerical simulation of gas flow during coal/gas outbursts

Summary A model of the gas flow in airways during an instantaneous outburst of coal and gas is formulated and solved numerically using MacCormack's explicit finite-difference scheme. This model is based on the assumption that geological structures, in-situ stresses and high-gas-pressure gradients play important roles in initiating an outburst, with the gas content and gas-pressure gradients being the most dominant factors. The fluid-dynamic processes that occur after an outburst are computed by the numerical integration of the complete time-dependent Navier-Stokes equations. The mixture velocity, the density and the gas-concentration profiles in both time and space domains (immediately after an outburst) are presented. The global results are useful in gaining an improved understanding of gas-flow patterns during coal/gas outbursts and in determining the range of the disturbance so that effective methods of control can be developed.Nomenclature a speed of sound - C gas concentration (mass) - C _v specific heat at constant volume - C _p specific heat at constant pressure - CFL Courant-Friedrichs-Lewy number - E total energy of the mixture - F the vector defined in Equation 27 - G the vector defined in Equation 28 - h entropy - h _i entropy at inlet - J _xi diffusion flux in the i-direction - k thermal conductivity of a gas - M Mach number - P pressure of a mixture (the partial pressure of gas) - P gas pressure - P _a atmospheric pressure     

Interaction among fractures and stress field computation of fracture systems

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黑水─泉州地学断面的重磁解释

讨论华南黑水─泉州地学断面的重磁解释。在解释中除应用常规的２．５维重磁异常反演外，还采用等密度线算法构制梯度层密度模型，用于分辨地壳密度细结构，以及计算自由地幔而深度用于分析上地幔密度的横向不均匀性。重磁模拟结果揭示了１０ｋｍ深度内的上地壳构造以及地壳与上地幔密度的分布。提出华南造山带以低密度上地幔为特征，它可能与上地幔的改造有关；四川盆地具有较高的上地幔密度，为未经改造的原始地幔。扬子克拉通与华南造山带的分界线与上地幔密度的分界线一致。根据布格异常、地表岩石密度和地形资料的综合分析，圈定出反映内生成矿作用深部标志的密度倒转区，可作为进一步找矿的远景区。