Shaft design criteria

Summary Criteria for shaft design are described and methods of design developed. Among aspects covered in detail are: selection of shaft locations; shaft collar design and determination of collar dimensions; shaft lining design and estimation of side pressures; shaft insets and sump design. Factors considered, apart from geotechnical criteria include constraints imposed by surface structures, mineral handling and water flows.     

Experimental Study of Mechanical Behaviour of Rock Joints Under Cyclic Loading

Summary Evaluation of the effects of small repetitive earthquakes on the strength parameters of rock joints in active seismic zones is of interest of the designers of underground constructions. In order to evaluate these effects, it is necessary to study the behaviour of rock joints under dynamic and cyclic loadings. This paper presents the results of a systematic study on the behaviour of artificial rock joints subjected to cyclic shearing. More than 30 identical replicas have been tested using triaxial compression devices under different conditions of monotonic and cyclic loading. At the first stage a few samples have been tested in monotonic loading modes under various confining pressures and rate of displacement. In the second series of tests, small cyclic loads were applied on the samples for increasing number of cycles, frequency levels and stress amplitudes. These were then followed by monotonic loading again. The variations of maximum and residual shear strengths for each test have been studied. The results show increase of shear strength as a result of the increase in confining pressure and they display decrease of shear strength due to the increase of rate of loading, number of cycles, frequency levels and stress amplitudes.     

Dispelling a myth? Second homes in rural Wales

Second homes have been a source of considerable controversy in Wales for more than three decades. In this article we argue that they have, in reality, become less important in recent times, with the market contracting during the 1990s and other more fundamental demographic changes and housing pressures coming to the fore. Second homes are a highly localized issue, affecting a minority of communities – though, at times, quite severely. Retirement and other housing pressures, however, bring more significant socio-economic changes and these pressures are all too frequently amplified by a planning system used to restrict housing supply rather than manage growth. This paper has three parts, beginning with a general review of the second home debate followed by an examination of the changing geography of second homes, showing how the distribution of these properties altered during the 1990s and how the market contracted. It ends with a review of secondary data, revealing that second homes are a relatively small component of wider processes affecting rural communities, though extremely significant in some areas.     

半无限空间中稳态P波在衬砌周围的散射

本文采用多级坐标和复变函数方法针对半无限空间中P波在一衬砌周围的散射问题提出了一种近似求解分析方法。具体做法是利用一个半径很大的圆来逼近半空间的直边界，将待解问题转化为全空间中P波在一圆孔和一衬砌周围的共同散射问题。我们预先写出问题波函数的一般形式解，利用边界条件并借助复数傅立叶级数展开把问题化为求解波函数中未知系数的无穷线性代数方程组，进而讨论了衬砌内外边界处动应力集中系数针对不同条件组合的分布和变化情况。算例结果表明：本文方法对于研究与P波（SV波）有关的散射问题是可行的。     

METEOROLOGICAL CHARACTERISTICS DURING THE SECOND MEIYU EPISODE IN 1998*

This article examined the meteorological features of the second Meiyu/Baiu episode(hereafter Meiyu Ⅱ) in 1998 and the results are summarized as follows:(1) The Meiyu Ⅱ period in 1998 has been the longest and the most delayed ending one since 1885,which caused the great flood around the Yangtze River Basin.The circulation situation in Meiyu Ⅱ is so typical that the average geopotential height and wind fields at 500 hPa and 850 hPa are very similar to monthly mean in June.The abnormal circulation in Meiyu Ⅱ is associated with an adjusting of the Okhotsk high and short period south-north oscillation of the subtropical high.(2) The heavy rainfall around the Yangtze River during Meiyu Ⅱ period is closely related to a persistent shear line,a clear eastward moving vortex structure and a very strong jet flow at lower levels.It is very clear that the strong divergence at higher levels and convergence at lower levels occurred in situ during Meiyu Ⅱ period.(3) It is very clear that the convective activity propagates eastward quickly with a period about 7 days during Meiyu Ⅱ period.     

THE MODELING IMPROVEMENT OF HURRICANE ANDREW BY THE TECHNIQUE OF IRREVERSIBLE THERMODYNAMIC OPERATORS

Although incorporating the horizontal diffusion into the atmospheric governing equations is apart of the dynamics of a model,it is based on the computational consideration originally,which isto overcome the nonlinear aliasing or computational instability and smooth the physical fields at thesame time.The generally used forms of the fourth-order diffusion,either linear or nonlinear,however,can not properly describe the real physical diffusion processes and thus affect theaccuracy of forecasting and modeling.In this paper,based on the nature of the physical diffusion.the scheme of horizontal diffusion of the MM5 Version 3 is improved according to the second law ofthermodynamics which controls the irreversable evolutionary direction of a many-body system andthe potential ability of the improvement of the new scheme in modeling accuracy is revealed byintroducing the technique suggested in this paper,via a theoretical case and the computational caseof the hurricane Andrew that landed on Florida in 1992.     

佛山市旅游信息系统开发

基于地理信息系统和多媒体集成的旅游信息系统开发模式可以融合GIS软件和多媒体软件二者的优点，在实践应用中有巨大的推广应用价值。文中从理论上探讨了GIS库中多媒体信息的链接和表达问题，以关系数据库为核心，把多媒体文件名信息存储在信息系统属库，依靠多媒体字段实现多媒体数据与地理信息系统图形和属性的关联，实现查询的基本概念。以此思路，佛山科技学院GIS技术实验室利用VB进行GIS和多媒体二次开发，成功地完成了佛山旅游信息系统的设计和开发。     

Quantitative Prediction for Deep Mineral Exploration

On reviewing the characteristics of deep mineral exploration, this article elaborates on the necessity of employing quantitative prediction to reduce uncertainty. This is caused by complexity of mineral deposit formational environments and mineralization systems as increase of exploration depth and incompleteness of geo-information from limited direct observation. The authors wish to share the idea of "seeking difference" principle in addition to the "similar analogy" principle in deep mineral exploration, especially the focus is on the new ores in depth either in an area with discovered shallow mineral deposits or in new areas where there are no sufficient mineral deposit models to be compared. An on-going research project, involving Sn and Cu mineral deposit quantitative prediction in the Gejiu (个旧) area of Yunnan (云南) Province, China, was briefly introduced to demonstrate how the "three-component" (geoanomaly-mineralization diversity-mineral deposit spectrum) theory and non-linear methods series in conjunction with advanced GIS technology, can be applied in multi-scale and multi-task deep mineral prospecting and quantitative mineral resource assessment.     

Thermomechanical model of hydration swelling in smectitic clays: I two-scale mixture-theory approach

A thermomechanical theory of hydration swelling in smectitic clays is proposed. The clay is treated as a three-scale swelling system wherein macroscopic governing equations are derived by upscaling the microstructure. At the microscale the model has two phases, the disjoint clay platelets and adsorbed water (water between the platelets). At the intermediate (meso) scale (the homogenized microscale) the model consists of clay particles (adsorbed water plus clay platelets) and bulk water. At the macroscale the medium is treated as an homogenized swelling mixture of clay particles and bulk-phase water with thermodynamic properties defined everywhere within the macroscopic body. In Part I, the mesoscopic model governing the swelling of the clay particles is derived using a mixture-theoretic approach and the Coleman and Noll method of exploitation of the entropy inequality. Application of this procedure leads to two-scale governing equations which generalize the classical thermoelastic consolidation model of non-swelling media, as they exhibit additional physico-chemical and viscous-type terms accounting for hydration stresses between the adsorbed fluid and the clay minerals. In Part II the two-scale model is applied to a bentonitic clay used for engineered barrier of nuclear waste repository. The clay buffer is assumed to have monomodal character with most of the water essentially adsorbed. Further, partial results toward a three-scale thermomechanical macroscopic model including the bulk phase next to the swelling particles are derived by homogenizing the two-scale model with the bulk water. A notable consequence of this three-scale approach is that it provides a rational basis for the appearance of a generalized inter-phase mass transfer between adsorbed and bulk water. Copyright © 1999 John Wiley & Sons, Ltd.     

基于DEM的四川省坡度图制作

第一次土地调查耕地坡度级由于采用传统方法进行量算,导致耕地系数、耕地净面积精度不高。为克服其不足,在四川省第二次土地调查中,以ArcGIS为平台,在对四川省DEM数据进行预处理的基础上,综合分析四川地形地貌特点,通过试验区验证来确定坡度计算模型进而开发坡度计算软件,制作完成按行政区划分幅（省、市、县）和按地形图分幅（1：10万、1：5万）的坡度图和坡度级图。通过对成果进行的大量验证工作（包括地形图验证和野外实地核查）表明成果中坡度级图斑和耕地图斑坡度级准确率高,数据可靠,并在四川省第二次土地调查耕地田坎样方布设以及数据库建设中全面应用。