The coda attenuation of the Yao''''an area in Yunnan Province

IntroductionThetravellingqualityfactorQofseismicwaveisoneofbasicphysicalparametersformeasuringthemediaattenuation(1/Q)intheearthandreflectionofinhomogeneityandinelasticityofthemedia,whichisusedinstudiesoffocalphysicsandengineeringearthquake.Qiscloselyrelatedtotheregionaltectonicactivityandseismicity.Thisfeaturehasbeenstudyingasoneoffactorsofearthquakeprediction(Chouet,1979;JinandAki,1986,1989).InYunnanregion,QIN(1992)andQIN,etal(1995)hadstudiedthefeaturesofregionalvariationofcodaQcandflu…     

Mechanical properties of calcareous silts in a hydraulic fill island-reef

Abstract

The mechanical characteristics of calcareous silt interlayers play an important role in the stability of island-reef foundations. Direct shear and consolidation tests were performed to study the relationship between the mechanical properties and the physical parameters of calcareous silt. Based on the consolidation test results and analysis of the settling examples, different calculation methods for soil settling were compared. The results show the following. (1) The relationship between the cohesion and water content of calcareous silt can be represented by an M-shaped curve. The water contents corresponding to the two peaks of the M-type curve increase with increasing dry density. (2) When the dry density is less than 1.33?g/cm³, increasing the density significantly improves the internal friction angle of calcareous silts. When the dry density of the calcareous silt is greater than 1.33?g/cm³, the internal friction angle is affected by both the dry density and the water content. (3) The shear strength decreases when the water content exceeds the optimum level. (4) The compressive modulus of calcareous silt is larger than that of terrigenous silt. Specifically, it decreases with decreasing dry density and increasing water content. (5) The stepwise loading method should be used to estimate the soil settling before fill engineering construction.     

A modified ISBA surface scheme for modeling the hydrology of Athabasca River Basin with GCM-scale data

A soil–vegetation–atmosphere transfer model (SVAT), interactions between the soil–biosphere–atmosphere (ISBA) of Météo France, is modified and applied to the Athabasca River Basin (ARB) to model its water and energy fluxes. Two meteorological datasets are used: the archived forecasts from the Meteorological Survey of Canada’s Global Environmental Multiscale Model (GEM) and the European Centre for Mid-range Weather Forecasts global re-analysis (ERA-40), representing spatial scales typical of a weather forecasting model and a global circulation model (GCM), respectively. The original treatment of soil moisture and rainfall in ISBA (OISBA) is modified to statistically account for sub-grid heterogeneity of soil moisture and rainfall to produce new, highly non-linear formulations for surface and sub-surface runoff (MISBA). These new formulations can be readily applied to most existing SVATs. Stand alone mode simulations using the GEM data demonstrate that MISBA significantly improves streamflow predictions despite requiring two fewer parameters than OISBA. Simulations using the ERA-40 data show that it is possible to reproduce the annual variation in monthly, mean annual, and annual minimum flows at GCM scales without using downscaling techniques. Finally, simulations using a simple downscaling scheme show that the better performance of higher resolution datasets can be primarily attributed to improved representation of local variation of land cover, topography, and climate.     

区域发展规划的人地系统动力学基础

区域发展规划研究的出发点是人地关系地域系统和可持续发展战略 ,人地关系的协调共生是区域发展规划的灵魂。文章依据耗散结构理论的基本观点提出了人地系统协调共生的4种状态 ,重点分析了人地系统组成要素及其相互关系在时空层次上的动态关联方式及动力结构 ,旨在为编制区域发展规划奠定坚实的动力学基础。     

河南省地热资源开发利用现状评价

基于河南省地热资源特点及其开发利用现状的基础上,分析总结了河南省各种类型地热水的开采情况。首先应用已采量与可采量的比值作为评价标准将地热水的开发利用程度为五类,评价了整个河南省新生界地热水、基岩地热水、温泉水的开发利用情况以及各地市城区的地热开采情况,提出河南省应积极地推广地热资源利用,对开采过热的地区要注意防止地热水位下降过快,对开采一般的地区要注意适度开发,对其他地区要结合自身实际鼓励开发。     

基于瓦片数据的DEM构建与显示

对于大规模地形而言,地形网格的实时动态绘制速度和质量一直是人们关注的重点。地形漫游在仿真、模拟、虚拟现实、游戏等领域都有广泛的应用。该文在研究多种层次算法的基础上,采用一种地形瓦片重组数据结构的方法实现实时高帧率的绘制大规模地形。分析了地形场景数据管理与实时调度,视相关多层次细节模型与可见性判断以及分层数据组织和瓦片数据绘制等关键问题,并给出了相应的解决方法,改进了视景体裁切重组地形数据的方法。实验结果表明该方法在保持地形逼真的前提下,有很好的绘制网格帧率和实时动态交互效果。     

强度和变形参数的变化对土工有限元计算的影响

在土工问题的数值分析中,包含变形模量E、泊松比 两个变形参数的增量线弹性模型是一种常用的计算模型,研究和掌握E和 两个参数对土工有限元计算的影响有助于分析计算成果。首先,设想固定某一个参数而观察另一个参数变化对计算结果的影响;然后,说明用强度折减有限元法分析土坡稳定安全系数时,实际上已同时考虑了变形参数的影响。可采用剪应力? xy的等值线近似形成滑动面,滑动面单元的应力水平S等于1和特征点的位移发生突变共同作为失稳判据;最后,是用强度参数为纽带探讨这两个变形参数的互相变化关系,即E愈大,则土的强度愈大,? 愈小。     

冀西北地区金矿类型研究

研究表明,冀西北金矿化集中区的众多金矿床（点）尽管具有共同的金矿源层,但其主要控矿因素及地质地球化学特征却存在着一定差异,这些差异决定了区内金矿床（点）存有三种类型：小营盘型、张全庄型和东坪型。该三类金矿均为多因复成金矿。     

The effective number of cycles of earthquake ground motion

The seismic response of any system that accumulates damage under cyclic loading is dependent not only on the maximum amplitude of the motion but also its duration. This is explicitly recognized in methods for estimating the liquefaction potential of soil deposits. Many researchers have proposed that the effective number of cycles of the ground motion is a more robust indicator of the destructive capacity of the shaking than the duration. However, as is the case with strong‐motion duration, there is no universally accepted approach to determining the effective number of cycles of motion, and the different methods that have been proposed can give widely varying results for a particular accelerogram. Definitions of the effective number of cycles of motion are reviewed, classified and compared. Measurements are found to differ particularly for accelerograms with broad‐banded frequency content, which contain a significant number of non‐zero crossing peaks. The key seismological parameters influencing the number of cycles of motion and associated equations for predicting this quantity for future earthquakes are identified. Correlations between cycle counts and different duration measures are explored and found to be rather poor in the absence of additional parameters. Copyright © 2004 John Wiley & Sons, Ltd.