中国台风强度等级与可能灾害损失标准研究

台风灾害给中国沿海地区造成了严重损失,进行台风风险评估将为台风灾害有效规避提供科学依据,探讨台风强度等级和灾害损失之间的关系是台风风险定量评估的基础。利用1954-2008年间登陆中国东南沿海的174场成灾台风路径数据和对应的灾情记录数据,对台风强度等级和承灾体(农作物、人口、房屋和社会经济)的8项指标的损失数量关系进行分析,并对台风强度等级与各项损失率指标之间的关系进行拟合,得出各项灾损指标的损失率曲线。基于台风强度等级划分标准和损失率曲线,建立了适合于我国的四个强度等级的台风灾害损失标准划分方案:微度、轻度、中度和重度,对应的损失率用承灾体的社会经济指标来表征。研究表明:当台风强度等级达到第4等级时,灾害造成的损失率均有较大幅度的增加。本文构建的台风灾害损失标准可为进一步定量评估承灾体脆弱性及损失风险提供依据和参考。     

非饱和土的应力状态变量研究

以热力学和连续介质力学的应力理论为基础,从非饱和土的土骨架平衡方程出发,导出了一系列应力状态变量,目前文献中所使用的应力状态变量都在其中。研究发现：非饱和土的应力状态变量有多种组合形式（5组以上）,不是惟一的;大多数应力状态变量与土的孔隙率、饱和度等物性指标孪生相伴;所有应力状态变量都具有应力的量纲,单纯孔隙率或饱和度及其组合都不构成应力状态变量;简化的Bishop有效应力公式和Fredlund倡导的两个应力状态变量都是简化了的应力状态变量,前者忽略了孔隙率的影响,而后者忽略了与孔隙率及饱和度的关联性。在选择应力状态变量时应考虑理论合理、应用方便、逻辑关系正确的原则,还应做一定的验证工作。     

高烈度区重力式挡墙基于性能的抗震设计方法研究

介绍基于性能抗震设计的核心理念,以支挡结构震害调查分析为背景,阐述开展高烈度区重力式挡墙基于性能抗震设计研究的必要性;构建重力式挡墙基于性能的抗震设计框架,归类分析现行规范与基于性能抗震设计的关键技术问题;依据支挡结构震害调查及大型振动台模型试验,提出位移指数可作为衡量挡墙抗震性能的量化指标,确定重力式挡墙基于性能抗震设计的性能准则及流程;经对比计算基于性能与规范抗震设计的挡墙算例,显示基于性能抗震设计的优越性,为高烈度区重力式挡墙基于性能抗震设计的工程应用提出建议。     

A prediction model for important mineral resources in China

Prediction models for mineral resources provide an analytical foundation and method to express the results of resource evaluations. The project “China National Mineral Resources Assessment Initiative” was conducted during 2006–2013, with the aim to determine the location, quantity, and quality of 25 important mineral resources occurring at depths of <1 km. There are currently 80 integrated prediction models on the scale of III–level metallogenic belts in use across China. The Huangshaping Pb–Zn polymetallic deposit, Hunan province, China, is used as a case study to establish methods and processes for developing a mineral resource prediction model that would be used for exploration targeting. The construction of prediction models requires the development of a classification scheme for the proposed prediction method appropriate for the prediction area. An initial metallogenic model is quantitatively transformed to a prospecting model, and then a prediction model. The incorporation of additional methodology, analysis of a comprehensive geological database, and correlation of asymmetric information between the well–explored typical deposit area and regional prediction area, yield an integrated prediction model. This paper also discusses the prediction modeling theory, and presents 12 models used for mineral assessments.     

A simple method to describe three-dimensional anisotropic failure of soils

In order to describe the anisotropic failure of soils caused by the internal fabric, isotropic failure criterion should be generalized to be anisotropic. This paper achieves the generalization by introducing a simple method, called anisotropic transformed stress method, which apparently differs from the common way. Physical interpretation of this method are analyzed further. Using this method, many existing isotropic criteria can become anisotropic in the same way, and will be expressed by a unified formula finally. To verify this method, anisotropic Unified Strength Criterion is used to predict the peak strength of anisotropic soils in different loading conditions.     

Multi‐slicing strategy for the three‐dimensional discontinuity layout optimization (3D DLO)

Discontinuity layout optimization (DLO) is a recently presented topology optimization method for determining the critical layout of discontinuities and the associated upper bound limit load for plane two‐dimensional and three‐dimensional (3D) problems. The modelling process (pre‐processing) for DLO includes defining the discontinuities inside a specified domain and building the target function and the global constraint matrix for the optimization solver, which has great influence on the the efficiency of the computation processes and the reliability of the final results. This paper focuses on efficient and reliable pre‐processing of the discontinuities within the 3D DLO and presents a multi‐slicing strategy, which naturally avoids the overlapping and crossing of different discontinuities. Furthermore, the formulation of the 3D discontinuity considering a shape of an arbitrary convex polygon is introduced, permitting the efficient assembly of the global constraint matrix. The proposed method eliminates unnecessary discontinuities in 3D DLO, making it possible to apply 3D DLO for solving large‐scale engineering problems such as those involving landslides. Numerical examples including a footing test, a 3D landslide and a punch indentation are considered, illustrating the effectiveness of the presented method. © 2016 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd.     

新疆阿尔金盘龙沟金矿高光谱蚀变矿物找矿标志研究

高光谱遥感技术是近年来兴起并逐渐成熟的蚀变矿物研究方法。盘龙沟金矿床围岩蚀变发育,主要蚀变类型包括硅化、绿泥石化、绢云母化、碳酸盐化、钠长石化、褐铁矿化等,蚀变与金矿化关系密切。文章通过航空高光谱遥感数据和地面光谱数据,提取和诊断盘龙沟金矿床的不同地段、不同地质体的蚀变矿物信息,研究分析金矿区的航空和地面高光谱蚀变矿物、蚀变矿物组合特征,以及矿区围岩蚀变特征,总结航空和地面光谱蚀变矿物分带找矿标志规律,结合金矿床地质矿产特征,系统剖析金矿床的综合找矿标志特征,构建盘龙沟金矿床高光谱蚀变矿物找矿标志;同时依据绢云母、绿泥石的诊断光谱,研究两种蚀变矿物的光谱变化特征,分析了金矿床围岩蚀变的形成条件和蚀变矿物的温压条件,进而初步推测盘龙沟金矿床为中低温热液型金矿,其矿体与围岩形成的环境条件不同。     

中亚南天山穆龙套型金矿地质背景、成矿特征和找矿策略

中亚南天山是世界上最重要的金矿带,以浅变质含碳质碎屑岩系为容矿岩石的穆龙套型金矿最为发育且规模巨大。将境内外南天山作为整体开展研究,有助于推进中国新疆南天山地区金矿的找矿持续突破。南天山是南天山洋在石炭纪末闭合时在Karakum—塔里木板块北缘形成的褶皱冲断带。南天山地区穆龙套型金矿的容矿地层为一套浅变质、变形强烈的含碳质细碎屑岩建造,对金矿化有明显预富集;区域内的大型韧-脆性变形带,剪切带及相关断裂系统是穆龙套型金矿的控矿构造;金矿区岩浆活动虽然较弱,但岩浆活动与成矿具有紧密的时空联系。矿体呈脉状、板状、透镜状,常以黄铁矿和毒砂为主要载金矿物,围岩蚀变以硅化、黄铁矿化、碳酸盐化最为发育。成矿年龄多为晚古生代,同位素示踪指示成矿流体、硫及成矿金属物质具有壳幔混源特征。"碳质岩系+构造变形+岩浆热液"是穆龙套型金成矿的关键控制因素。按照总体控矿特征,探讨了中国新疆南天山地区穆龙套型金矿床的主要找矿策略。     

甘肃省岷县绿沙金矿地质特征

绿沙金矿位于南秦岭褶皱带,合作—鹿儿坝—崖湾金、汞、锑等多金属成矿带上,处于鹿儿坝金矿西北部11 km处。矿区内圈定以Au为主的土壤综合异常4处,异常走向NW向为主,与区域地层展布及构造线方向一致;通过对AT3异常检查圈出金矿体3条,矿体赋存于中三叠统古浪堤组地层中,严格受断裂构造带控制,矿体走向以NW向为主,矿石具较强的褐铁矿化、硅化。本文在对矿区地质及矿体特征客观认识的基础上,分析总结了矿区的控矿因素和找矿标志,并与邻区的鹿儿坝金矿进行了对比。为该区及成矿带找矿工作具有借鉴意义。     

关于地震前兆的判据问题

地震前兆是地震预报的基础,这个基础是由一些个案构成的.应该把地震前兆研究放在地震预报研究之前.对地震前兆的识别需要判据.不能把权威学者的只言片语或者流行的假说当作判别地震前兆的最终凭据,而且目前不具备进行地震前兆统计的基本条件.综合人们以往的认识,识别地震前兆异常有3个自然判据:1)有正常背景;2)非干扰影响;3)与地震相关.其中,与地震相关是核心.可靠的地震前兆判定需要精确的观测资料.对地震前兆判据的研究对制定地震研究规划和观测规范都有指导作用.