区域气候变化脆弱性综合评估研究进展

区域脆弱性评估为脆弱性地区农户摆脱贫困、区域持续发展和政府制定适应策略提供科学依据.由于区域内部人地系统的复杂性,区域的脆弱性定量评估较为困难.中国脆弱性研究起步较晚,关注较早的是脆弱性区域的分布,但对区域内脆弱人群的脆弱性研究较少,认识上的不足影响了国家和地方政府制定科学的适应政策和措施.本文介绍了对脆弱性的认识,梳...     

地形湿度指数算法误差的定量评价

地形湿度指数(TWI)能够定量指示地形对土壤湿度空间分布的控制,是一种应用广泛的地形属性.目前基于栅格DEM的TWI计算方法结果各异,因此有必要对'TWI算法进行定量评价.对TWI算法通常是应用实际DEM数据进行评价.但实际DEM中存在的数据源误差会干扰对算法误差的评价.针对该问题,本文介绍了一种用不含数据源误差的人造...     

Quantitative risk assessment of landslide by limit analysis and random fields

Risk may be estimated by multiplying the probability of failure by the consequence. This is acceptable for systems that have a single mode of failure. For systems that have multiple failure modes, such as landslides, the consequences should be assessed individually for each of the failure modes. This paper proposes a new framework of quantitative landslide risk assessment, in which consequences are assessed individually. The framework is generally applicable, and the landslide risk assessments of two typical slopes are presented.     

土壤重金属生态危害评价：以典型金矿区为例

通过对典型矿区土壤重金属污染现状与分布规律研究,发现土壤污染的主要因子是Cd、As、Hg、Cu、Pb、zn等重金属元素污染,金矿三废排放是土壤重金属污染的主要来源。一号金矿区Hg、Cd、As三种元素对土壤危害的贡献率之和达到94％,其中仅Hg元素的贡献率就达到了77％。二号金矿区Hg、Cd、As、Pb、Cu五种元素对土壤危害的贡献率之和达到97％,其中仅Hg元素的贡献率就达到了61％。金矿区土壤重金属元素潜在生态危害强、很强的土壤样品数量占总数的66．54％,占金矿专题研究区控制总面积的79．51％,土壤潜在生态危害严重,本成果为金矿区土壤污染防治提供了科学依据。     

New insights into the size and timing of the Lawn Hill impact structure: relationship to the Century Zn – Pb deposit

The Lawn Hill circular structure in northwest Queensland contains unambiguous evidence of an extraterrestrial impact, including planar deformation features in quartz, impact diamonds, widespread shatter cone formation and impact melt breccia in the Mesoproterozoic basement. The question of its relevance to ore genesis is investigated because the world-class Century Zn – Pb deposit is situated at the conjunction of the 100+ km Termite Range Fault and the previously defined margin of the impact structure. The impact structure is considered to be a 19.5 km wide feature, this constrained in part by the outer margin of an annulus of brecciated and highly contorted limestone. New evidence is presented indicating impact into this Cambrian limestone, including: (i) ‘dykes’ of brecciated Cambrian limestone extending hundreds of metres into the Mesoproterozoic basement; (ii) highly contorted bedding in the limestone annulus compared with essentially undeformed limestone away from the impact site; as well as (iii) a 1 Mt megaclast of Mesoproterozoic Century-like ore suspended in the limestone. Through aerial photograph analysis, large-scale convoluted flow structures within the limestone are identified, and these are interpreted to indicate that parts of the Cambrian sequence may have been soft or only semi-consolidated at the time of impact. This highly contorted limestone bedding is suggested to represent slump-filling of an annular trough in response to impact-induced partial liquefaction of a sediment veneer. The age of impact is therefore considered to be concurrent with limestone formation during the Ordian to early Templetonian, at 520 – 510 Ma. Formation of the Century deposit is found to be unrelated to impact-generated hydrothermal activity, although some minor hydrothermal remobilisation of metals occurred. However, there was macro-scale remobilisation of gigantic ore fragments driven by impact-induced lateral and vertical injection of limestone into the Proterozoic sediments. The limestone-filled annular trough surrounds a 7.8 km diameter central uplift, consistent with formation of a complex crater morphology.     

Reliability of shallow foundations designed against bearing failure using LRFD

Worldwide, there is growing interest in the development of a rational reliability-based geotechnical design code. The reasons for this interest are at least two-fold; first, geotechnical engineers face significantly more uncertainties than those faced in other fields of engineering, therefore there is a need to properly characterize and deal with these uncertainties. Second, for decades, structural engineers have used a reliability-based design code, and there is a need to develop the same for geotechnical engineers, in order that the two groups can ‘speak the same language’. This paper develops a theoretical model to predict the probability that a shallow foundation will exceed its supporting soil's bearing capacity. The footing is designed using characteristic soil properties (cohesion and friction angle) derived from a single sample, or ‘core’, taken in the vicinity of the footing, and used in a load and resistance factor design approach. The theory predicting failure probability is validated using a two-dimensional random finite element method analysis of a strip footing. Agreement between theory and simulation is found to be very good. Therefore, the theory can be used with confidence to perform risk assessments of foundation designs and develop resistance factors for use in code provisions.     

陕北三叠纪煤田蟠龙至高家屯勘查区5号煤层顶板工程地质特征

研究区5号煤层位于三叠系瓦窑堡组第四段上部,煤层直接顶以泥岩、砂质泥岩为主,老顶以粉砂岩、泥岩和细粒砂岩为主,从岩性分布来看,总体呈现出向上变粗的沉积层序,对应的顶板类型为下软上硬型.进一步分析其岩石力学性质、测井曲线与岩体质量指标,参考岩层厚度、层理及裂隙等,综合分析确定该区5号煤层顶板属基本稳定型.该研究为煤矿的安全生产提供了技术支持.     

重庆嘉陵江干流饮用水水源地水质分析与健康风险评价

利用WQI模型和水环境健康风险评价模型对20092011年嘉陵江干流重庆段6个饮用水水源地进行评价,并将影响这两种方法的主要因素进行分析比较。结果表明,6个水源地水质总体较好且城郊差异不大,但健康风险等级普遍偏高,城区明显高于郊区;各污染物都可能影响到WQI值,而砷、镉尤其是六价铬等化学致癌物是影响总健康危害风险的主要因素。两种模型侧重点不同,综合运用将更有助于客观全面评价水体质量和对人体健康的影响。     

基于层次分析法的矿山岩土工程系统环境质量多目标评价模型

矿山开发给矿区环境带来了负面影响,对矿山环境质量进行评价是实现矿业可持续发展的必要手段。笔者建立了矿山岩土工程环境质量多目标评价指标体系,运用层次分析法确定出各个评价指标的权重; 规定了分级规则,并对各个评价指标进行了分级; 建立了矿山岩土工程体系环境质量多目标综合评价模型,并将该模型应用于矿山实际,得出该矿山环境质量较差,需及时采取措施进行治理。