反转构造与造山带研究

反转构造的研究已成为造山带构造研究的一个重要内容。反转构造模拟和实践所得出的断层组合形态和形成顺序有助于对造山带及前陆褶皱和逆冲带的正确认识。由于张性断层的控制作用，６０年代中期发展起来的薄壳构造模式在现实中并不普遍适用，构造剖面的平衡恢复因此亦需加倍谨慎。在造山带研究中，还需注意反转构造与走滑构造之间的区分。     

贵州省石炭纪早期古土壤的发现及其意义

古土壤蕴涵着古老时期的大气氧、二氧化碳以及生态植被的演化信息 ,利用有效的手段提取这些信息并据此推测古气候环境。在贵州省的遵义苟江、道真县、正安县等地发现了保存完好的石炭纪早期的古土壤剖面 ,为恢复该地质时期云贵高原的大气氧演化、二氧化碳浓度与生态植被提供了天然的现场条件。     

Hydrodynamic characteristics of ship sections in shallow water with complex bottom geometry

The method of boundary integral equation developed by the authors was applied for computing inertial and damping characteristics of ship sections for the cases of multi-stepped and inclined bottoms. Comparative calculations for three typical ship hull sections were performed and analyzed. The frequency-dependent data computed for these ship sections can be used to assess the bottom geometry's influence onto the ship motions in waves by means of the strip theory. Limiting values of the same characteristics corresponding to the close-to-zero frequency can also be used for estimation of hydrodynamic forces in manoeuvring over shallow and confined waterways.     

Two-dimensional numerical approach for the vibration isolation analysis of thin walled wave barriers in poroelastic soils

This paper is concerned with the vibration isolation efficiency analysis of total or partially buried thin walled wave barriers in poroelastic soils. A two-dimensional time harmonic model that treats soils and structures in a direct way by combining appropriately the conventional Boundary Element Method (BEM), the Dual BEM (DBEM) and the Finite Element Method (FEM) is developed to this aim. The wave barriers are impinged by Rayleigh waves obtained from Biot’s poroelasticity equations assuming a permeable free-surface. The suitability of the proposed model is justified by comparison with available previous results. The vibration isolation efficiency of three kinds of wave barriers (open trench, simple wall, open trench-wall) in poroelastic soils is studied by varying their geometry, the soil properties and the frequency. It is found that the efficiency of these wave barriers behaves similarly to these in elastic soils, except for high porosities and small dissipation coefficients. The efficiency of open trench-wall barriers can be evaluated neglecting their walls if they are typical sheet piles. This does not happen with walls of bigger cross-sections, leading in general to efficiency losses. Likewise, increasing the burial depth to trench depth ratio has a negative impact on the efficiency.     

Unravelling the spirals: a serial thin-section study and three-dimensional computer-aided reconstruction of spiral-shaped inclusion trails in garnet porphyroblasts

Abstract Seventy-seven spatially orientated, serial thin sections cut from a single rock reveal changes in the geometry of spiral-shaped inclusion trails (SSITs) in garnet porphyroblasts. The observed SSITs are doubly curved, non-cylindrical surfaces, with total inclusion-trail curvature decreasing systematically from the cores to the rims of porphyroblasts. The three-dimensional geometry of the SSITs, reconstructed with the aid of computer graphics, shows that the orientations of spiral axes defined by the SSITs are not related in any expected nor predictable way to the main foliation in the matrix. This suggests continued deformation after or during the latest stages of porphyroblast growth, which has important implications for the use of SSITs as shear-sense indicators. Whether the formation of SSITs involves significant porphyroblast rotation with respect to a geographically fixed reference frame cannot be determined from the available data.     

De-bugging the 'millipede' porphyroblast microstructure: a serial thin-section study and 3-D computer animation

ABSTRACT Seventy-five spatially orientated, serial thin sections cut from a single rock containing ‘millipede’ porphyroblast microstructure from the Robertson River Metamorphics, Australia, reveal the three-dimensional (3-D) geometry of oppositely concave microfolds (OCMs) that define the microstructure. Electronic animations showing progressive serial sections of the 3-D microstructure are made available via the World Wide Web. The OCM amplitudes decrease regularly from a maximum in near-central sections to a minimum in near-marginal sections, whereas the OCM interlimb angles increase regularly from a minimum in near-central sections to a maximum in near-marginal sections. These observations illustrate that the OCMs are noncylindrical surfaces with culminations located in near-central sections. Because the porphyroblast cores appear to have been present before significant development of the syn-OCM foliation, all of the OCMs were formed by heterogeneous extension around these cores. The overall geometry of the OCMs described here reflects the strain state, and cannot be used to constrain deformation paths.     

乌东德水电站泄洪洞进口边坡特殊岩体工程地质性状及稳定性研究

金沙江乌东德水电站左岸泄洪洞进口正面坡最大坡高150m, 边坡结构为反向坡。边坡主要位于中元古界会理群因民组第二段第一亚段(Pt22-1y)薄层状陡倾大理岩化白云岩地层中, 层面附绢云母薄膜, 层间劈理发育。岩体完整性较差, 岩体质量主要为Ⅳ级。本文通过岩石及充填物镜鉴、室内及现场物理力学试验等手段相结合的方法对该段岩体的岩性特征、结构特征、物理力学特性进行研究。以此为基础, 分析与评价由该岩体构成的边坡的稳定性与变形破坏模式, 为支护设计提供依据。通过变形监测成果分析, 说明边坡支护措施的有效性与及时支护的必要性。本文对由特殊地质体构成的边坡的稳定性研究工作具有重要的借鉴作用。     

青海湖江西沟黄土记录的环境演变

青海湖地区是全球变化研究的热点区域,对全球气候环境变化极其敏感。末次冰消期是青海湖地区风成沉积物发生广泛堆积的时期,也是青海湖地区气候环境发生重要变革时期。通过对青海湖江西沟JXG1和JXG2黄土剖面的研究,重建了末次冰消期以来的环境演变记录。结果指示:(1)13~11.5 kaBP,剖面主要发育砂质黄土,青海湖区总体环境从冷干向相对温暖湿润的凉干环境过渡;(2)11.5~5 kaBP左右,剖面主要发育古土壤层,特别是9~5 kaBP时期,水热组合匹配达到最佳,气候呈现暖湿状态;(3)5 kaBP以来,干湿冷暖交替,尘暴频繁,植被盖度降低,气候进入相对不稳定状态。江西沟黄土剖面记录与青海湖湖泊钻孔和黑马河黄土剖面记录的气候变化过程具有一致性,红度指标是记录环境演变的敏感指标。末次冰消期以来该区黄土沉积主要受控于北半球高纬度夏季太阳辐射驱动的冰量变化,西风带扮演了北大西洋和青藏高原东北部"冷空气传输机"的角色。     

金刚石薄壁工程钻在粉喷桩取芯施工中的应用

本文简述了金刚石薄壁工程钻在高速公路软路基处理的粉喷桩取芯中的使用效果,阐明了金刚石薄壁工程钻粉喷桩取芯是一种理想的方法,具有广阔的推广应用前景。     

Fast imaging and inversion of on and off shore electromagnetic data

We consider thin layer algorithms for inversion of electromagnetic data acquired on large experimental grids. These algorithms do not involve targeted search of the model parameters. Instead, they determine an integrated characteristic of the model, i.e. heterogeneous conductance or transverse resistance, using a filtration technique developed for thin layer models, which adequately represent the geo-electric situation by a sequence of laterally homogeneous and heterogeneous layers. The corresponding filter reflects impedance/admittance relations between different components of the electromagnetic field in the stratified part of the model. Convolution of such filters with the data obtained from experimental measurements represents the most time consuming part of the computation. The convolution is carried out using a high performance algorithm, which makes the process of inversion extremely fast. The choice of a particular inversion algorithm is dictated by the specific geo-electric situation in the area of interest and the electromagnetic data subject to interpretation. Typically, most computations can be carried out in up to several minutes using a regular desktop or laptop PC.We restrict our consideration to two simplest algorithms for determination of the conductance of heterogeneous conductive layers (S-algorithm) and the transverse resistance of heterogeneous resistive layer (T-algorithm). The algorithms can be useful for interpretation of data acquired in on- and off-shore conditions with natural and controlled sources. Inversion can be jointly carried out for data sets collected for different source locations, at different frequencies, etc. Likewise, the algorithms can be used for interpreting the data collected using a moving source.Performance of the algorithms is demonstrated on a set of test inversions of numerically simulated data sets. The first group of the examples is typical for environmental applications. It is studied using the S-algorithm applied to natural and controlled source measurements for shallow and deep targets. The T-algorithm is applied for delineation of a gas hydrate type of reservoir using the data numerically simulated for such a problem.In geo-electrical situations that can be addressed using thin layer models, results of inversion hardly require any further elaboration. For instance, this happens when parameters of the heterogeneous layer satisfy thin layer conditions and its thickness can be determined from seismic measurements. When this is not the case, the model found by a thin layer inversion usually reveals correct location of the anomalous body and provides reasonable estimate of its integrated electric properties. In such situations the algorithm works as an imaging technique, which together with seismic information on the layer boundaries provides a justified initial model for a full scale 3D inversion and hopefully allows for avoiding pitfalls associated with a straightforward application of more traditional 3D inversion algorithms.