某些测震学指标与地震相关性研究

通过对１０项测震学指示宾１０ａ的大范围时空扫描得出的有震和无震“预报”进行了与５．０级以上的地震的相关性研究,结果证明这１０项指标当显性水平较低时,均可通过统计检验,表明是有效的提取异常指标。作还依统计检验结果对１０项测震学指标与地震相关性好坏进行了排序,并通过分析得到各指标今后优化方向．     

武宁陆相红盆沉积特征与演化浅析

本文依据1:5万区调资料,扼要介绍了武宁陆相红盆填图单位的拟定、表示方法及工作原理的应用,重点叙述了红盆内多个冲积扇体特征及其之间的叠覆关系,阐明了盆缘断裂是控制红盆成生、发展演化的主导因素。对红盆成生及演化、时代也作了初步探讨。     

Ck-Reconstruction of Surfaces from Partial Data

In this paper, we study the problem of constructing a smooth approximant of a surface defined by the equation z = f(x ₁, x ₂), the data being a finite set of patches on this surface. This problem occurs, for example, after geophysical processing such as migration of time-maps or depth-maps. The usual algorithms to solve this problem are picking points on the patches to get Lagrange's data or trying to get local junctions on patches. But the first method does not use the continuous aspect of the data and the second one does not perform well to get a global regular approximant (C ¹ or more). As an approximant of f, a discrete smoothing spline belonging to a suitable piecewise polynomial space is proposed. The originality of the method consists in the fidelity criterion used to fit the data, which takes into account their particular aspect (surface's patches): the idea is to define a function that minimizes the volume located between the data patches and the function, and which is globally C ^k. We first demonstrate the new method on a theoretical aspect and numerical results on real data are given.     

Adventures in Data Analysis: The TAO Array and the 1997–1998 El Ni?o

Traditional undergraduate education in earth sciences does not emphasize data acquisition, analysis, or assessment. However, arrival of the information age dictates that earth sciences graduates be imbued with fundamental skills to organize, evaluate and process large data sets. Fortunately, the proliferation of remotely sensed data and its availability via the Internet provides many opportunities for earth science educators to meet these needs. Exercises to introduce students to data analysis have been designed utilizing data from the Tropical Atmosphere–Ocean (TAO) Array and the 1997–1998 El Niño episode in the tropical Pacific Ocean. The TAO Array is a grid of 69 buoys moored across the equatorial Pacific Ocean (8°N to 8°S and 95°W to 143°E) recording environmental data relevant to El Niño—Southern Oscillation (ENSO) processes. Data from the TAO Array is available in near-real-time (http://www.pmel.noaa.gov/toga-tao/realtime.html) or as archived ASCII files (http://www.pmel.noaa.gov/toga-tao/data-delivery.html) providing daily (sometimes hourly) records of environmental parameters for each buoy in the grid. Student exercises in data analysis begin with downloading data from buoy locations, parsing the data into spreadsheets, and organizing data by environmental parameter into yearly and monthly data sets. Analyses of reconstructed data include calculations of long-term averages of environmental parameters, seasonal climatologies, monthly climatologies and calculation of long-term, seasonal, and monthly anomalies. Finally, monthly anomaly maps produced by students are loaded sequentially into GIF-animation software to create time-series images illustrating the progress and development of the 1997–1998 El Niño event.     

Hydrogeology of a coal-seam gas exploration area, southeastern British Columbia, Canada: Part 1. Groundwater flow systems

Discovery of high contents of methane gas in coals of the Mist Mountain Formation in the Elk River valley, southeastern British Columbia, Canada, has led to increased exploration activity for coal-seam gas (CSG). CSG production requires groundwater abstraction to depressurize the coal beds and to facilitate methane flow to the production wells. Groundwater abstraction will have hydrodynamic effects on the flow system, and an understanding of the groundwater flow system is needed to evaluate these effects. The purpose of this paper is to describe the groundwater flow system in the area by means of a groundwater flow model and interpretation of hydrochemical and isotopic analyses of groundwater and surface water. Groundwater flow for the Weary Creek exploration area is modeled in two vertical sections. The model domains, based on classic upland–lowland conceptual flow models, are approximately 10,000 m long and 4,000 m deep. Each consists of a fixed water-table boundary and no-flow boundaries along the traces of major faults. Steady-state groundwater flow is calibrated to hydraulic-head, streamflow, and groundwater-recharge data. Simulated steady-state velocity fields define regional and local flow components consistent with the conceptual model. The results are consistent with regional trends in δ²H, δ¹⁸O, tritium, and TDS, which define two distinct groundwater groups (A and B) and a third of intermediate composition. An active, shallow, local flow component (group A) is recharged in beds cropping out along subdued ridges; this component discharges as seeps along lower and mid-slope positions in the southern part of the study area. The waters are tritiated, relatively enriched in δ²H and δ¹⁸O, and have low TDS. A deeper regional flow component (group B), which originates at a higher altitude and which discharges to the Elk River valley bottom, is characterized by non-tritiated groundwater with relatively depleted δ²H and δ¹⁸O, and higher TDS. Groundwater contributes less than 10% of the total direct flow to the Elk River, as indicated by flow measurements and by the absence of group A and group B characteristics in the river water. Thus it is hypothesized that groundwater extraction during CSG production will have little impact on the river. The groundwater flow model developed in this work is used in a companion paper to further test this hypothesis. Electronic Publication     

Mineral variation in anorthositic, troctolitic, and adamellitic rocks of the Barth Island layered structure in the Nain anorthosite complex, Labrador

The Barth Island layered structure is an oval, 6 by 9 km body, consisting of rhythmically layered adamellitic rock in the center which grades outward through jotunite into troctolite. Farther outward the sequence repeats itself in reversed order, strongly reduced in magnitude and finer grained; the adamellitic zone is followed by jotunite which grades into coarse-grained leuconorite and into anorthosite of the Nain complex. The Barth Island structure, having an inverted conical base topped by a hemispherical depression, seems to represent a distorted sequence of rock layers with troctolite at the bottom, grading upward into adamellitic rocks which grade into anorthosite at the top. Trend-surface analysis demonstrates the regional variation of plagioclase and orthopyroxene compositions in the troctolite—adamellite sequence of the central part of the structure. The fits for the second- and third-degree surfaces are good and significant at the 99 percent level. The regression line for compositional variation in coexisting plagioclase and orthopyroxene in all analyzed rocks has a correlation coefficient of r² = 0.78. The difference between the trends in the troctolite—adamellite sequence and the anorthosite—adamellite sequence is insignificant. The regression curve for compositional variation in coexisting orthopyroxene and olivine has a correlation coefficient of r² = 0.98. The curve shows good correlation with the experimentally established partitioning curve of Medaris, which indicates that equilibrium conditions prevailed during formation of the olivine—ortho-pyroxene pairs. The results suggest that the troctolite—adamellite sequence and the anorthosite—adamellite sequence are products of fractional crystallization, possibly from the same parental magma.     

空孔直眼掏槽成腔模型理论与实践分析

空孔直眼掏槽是隧道或井巷掘进的主要方法之一。基于典型空孔掏槽炮眼布置,分析了掏槽眼爆破形成空腔的物理力学过程;建立了空腔形成的物理和力学模型;研究了腔内碎石在高压爆生气体作用下的抛射过程;得出了空腔尺寸的理论计算方法。槽腔岩石介质破碎和外端部漏斗形成取决于掏槽眼装药爆炸动作用;碎石的抛出率与炸药性质、岩石性质和爆破参数有关。理论分析与在某矿进行的48次试验结果有较好的吻合性。     

Simulations of a coupled hydro-chemo-mechanical system in rocks

A coupled hydro-chemo-mechanical numerical model is developed for these coupled phenomena in many engineering fields. The model has been applied to predicting the response of a stressed rockmass column to an injected reactive fluid (reagent) flow. The response includes evolutions of porosity, permeability, reagent and mineral concentrations during dissolution. In the model, the progress of dissolution is defined by the change in porosity ratio and the porosity increases with dissolution assuming there is no precipitation. The numerical evolutions of porosity, permeability, reagent and mineral concentrations during dissolution are validated against steady state solutions. The model results show that these evolutions are regulated to a certain extent by the applied external loadings: an applied extensional stress enhances the progress of the dissolution process while an applied compression stress slows the progress of the dissolution process. This revised version was published online in July 2006 with corrections to the Cover Date.     

周期温度边界条件下一维融化固结特性研究

在周期温度边界条件下,冻土呈现出与常温边界不同的融化固结特性. 基于融化固结理论提出了一种适用于周期温度边界条件下融化固结计算的数值模拟方法,并通过试验验证了该方法的有效性. 通过对比分析试验及数值结果表明,提出的数值方法能够很好地描述周期温度边界条件下冻土的融化固结特性. 同时,融化深度和变形均随时间呈现出阶梯型的变化趋势. 这是周期温度边界下土体融化固结行为最显著的特点. 随着冻融次数的增加,融化深度和变形均趋近于常温边界条件下的结果,这表明若干个冻融循环后周期温度边界对融化固结行为的影响将逐渐消失.     

中国蓄滞洪区洪水管理与可持续发展途径

蓄滞洪区的行蓄洪启用频率和蓄水方式决定着洪水管理与可持续发展途径,影响流域经济社会的可持续发展.根据各大流域蓄滞洪区的设计启用频率,设置了未来35年内蓄滞洪区发展的3种情景:维持现状、部分水库化和部分湿地化,构建了涵盖防洪、社会经济和生态发展等因子的途径选择指标体系,运用数据包络分析法(DEA),识别了不同设计启用频率的蓄滞洪区洪水管理与可持续发展的最优途径.结果表明:① 不同设计启用频率的蓄滞洪区在建成35年内,部分湿地化情景是中国70%蓄滞洪区的最优发展途径.② 设计启用频率50年一遇是蓄滞洪区发展途径选择的边界值;当等于或低于50年一遇时,部分湿地化是其最优途径;当高于50年一遇时,维持其现状是最优途径.