Spatio-temporal Distribution of Three Kinds of Flash Droughts over Agricultural Land in China from 1983 to 2015

At present, flash drought occurs globally and regionally and causes a lot of socio-economic loss in a very short time. Therefore, flash drought has been regarded as one of the hottest issues in drought research. However, flash drought monitoring, prediction and decision-making have encountered a lot of challenges due to its multiple driven factors and complex spatio-temporal process. Aiming at this problem, this paper focused on the agricultural land in China, and analyzed the spatio-temporal distribution of three kinds of flash droughts (i.e., precipitation-deficit, high-temperature, and composite flash droughts) from 1983 to 2015. We studied the occurrences, duration, spatial distribution, temporal distribution, and trend of all three kinds of flash droughts. Our results demonstrated that, the occurrences of flash drought agricultural land in China increased year by year, among which high-temperature flash drought increased dramatically; duration of flash droughts had different trends, but the variations were relatively smooth; Northeast China was identified as a vulnerable area of flash drought, indicating more flash drought events and longer duration; flash droughts in China were found to concentrate in spring (high-temperature drought) and summer seasons (precipitation-deficit drought). This study is helpful for building new flash drought monitoring method and system, and it is also valuable for flash drought preparedness on regional scale.     

井筒冻结孔解冻涌水发生机制及其控制技术

针对冻结井筒解冻后频繁发生涌水灾害的情况,通过工程实例分析了冻结技术、井筒地层条件及解冻涌水特征。结果表明,涌水发生是由于解冻后冻结止水帷幕失效,冻结管周围地层介质渗透性增强,介质接触界面粘结强度降低而致界面缝隙扩大连通,使冻结钻孔连通含、隔水层而形成竖向导水通道,通道内高压水通过井筒薄弱部位发生涌水。采取在井筒外围适宜地层开挖环形巷道,在环形巷道内逐个切断冻结管并向冻结管内外注浆加固,最后将环形巷道用混凝土回填,形成人工隔水塞层。利用RFPA^2D-Flow渗流耦合模型验证了该治理方案的可行性,且利用FLAC^3D程序计算出环形巷道距离井壁7.50 m是最佳开凿位置。经该措施处理后的井筒涌水由原来的90 m³/h降低至2 m³/h,且井筒保持了稳定。     

对勘查规范中“可行性评价”的理解与建议

经过对国家和行业标准中有关煤矿床经济意义可行性评价工作要求的梳理,认为《煤、泥炭地质勘查规范》和《煤炭地质勘查报告编写规范》中有关可行性评价的规定由地勘单位提交可行性研究相关内容,与《关于全面实施〈固体矿产资源/储量分类〉国家标准和勘查规范有关事项的通知》有相抵之处,一是地勘单位一般不具备可行性评价的资质,也不拥有从勘探到开采再到营销各环节的专业人员,提供准确的可行性评价内容困难;二是若由非勘查部门提供相关内容,则地质报告的评审与可行性评价的研究则存在程序的不可操作性。建议修改现行《煤、泥炭地质勘查规范》与《煤炭地质勘查报告编写规范》中的相应条款,规定地勘单位在各勘查阶段仅进行概略研究的相关工作并体现在地质报告中。     

Advance in Pollen Source Area

The conception of pollen source area has attracted broadly attention since it was proposed in the 1960s. In this paper,it can be subdivided into Normal Source Area of Pollen (NSAP) and Relevant Source Area of Pollen (RSAP) based on reviewing former studies and our recent work of vegetation survey and pollen analysis in the Northern China. The NSAP means a source area of pollen input a sedimentary basin,indicating a distance area beyond where the pollen contents of major pollen types do not show evident increase with increased distance. The RSAP means a source area of pollen assemblages in a basin has the closest relationship with surrounding plants,indicating a distance area beyond where the relationship between pollen assemblage and surrounding vegetation do not show obvious increase with increased distance. The changes of sedimentary basins radii and pollen grain size influence the NSAP and RSAP evidently. Wind speed also changes the NSAP, but does not significantly affect RSAP. The pollen of a sedimentary basin is composed of local pollen,regional pollen and extra regional pollen,which usually account for 30%~45%,25%~60% and 10%~30%,respectively. Local pollen which refers to the pollen coming within the RSAP range,is a reflection of the surrounding vegetation,and has important implications to the reconstruction and succession of local vegetation. Regional pollen which refers to the pollen coming from within the range of NSAP and excluding the range of local pollen,is the important carrier of studies for vegetation restoration and climate change. The pollen that comes outside the range of NSAP is called Extra regional pollen,which is mainly from greater distance by upper air flow,and has no indicator significance to the regional vegetation.     

GCTS空心圆柱扭剪仪反压饱和试验探究

GCTS空心圆柱扭剪仪是研究土体在循环荷载下的主应力轴旋转的理想仪器。如何使用GCTS空心圆柱扭剪仪对软土空心试样进行反压饱和才能使后续试验结果更精确,探究了以GCTS空心圆柱扭剪仪为试验平台,对空心试样进行了反压饱和的试验方法。总结了空心扭剪仪反压饱和的3种加压方式：手动加压、自动加压和连续加压方式。通过一些试验探究了每种加压方式所对应的合理性参数。确定了适合吹填土的压差为15kPa。确定了孔压稳定的标准为：如果孔压在1min内的变化值小于围压和反压之间压力差的5％,则认为孔压稳定。     

GIS-based multi-dimensional risk assessment of the grassland fire in northern China

This study presents a methodology for risk analysis and assessment to manage grassland fire in northern China based on the Geographical Information Systems from the viewpoints of climatology, geography, disaster science, and environmental science and so on. Using natural disaster and risk assessment theory, a multi-dimensional grassland fire risk index (MGFRI) was proposed by integrating weighted comprehensive method, analytic hierarchy process, and fuzzy gamma method into natural disaster risk index. The developed MGFRI will be an easily understandable tool to manage grassland fire by comparing the risk of regions in the northern China and relative contributions of various factors, for example, hazard, exposure, vulnerability, and management ability. A scale of one to five was derived to measure the risk degree. It shows that 4.4?% of grassland falls in the category of ??very high?? risk, followed by 9.6, 19.1, 60.9, and 5.9?%, respectively, in the categories ??high??, ??middle??, ??low??, and ??very low??. The assessment results show reliability by test. The results in this study are intended to support local, provincial, and national government agencies to: (1) make resource allocation decisions; (2) make high-level planning decisions; and (3) raise public awareness of grassland fire risk, its causes, and ways to manage it.     

右江裂谷区三叠系岩石物性特征及其与金矿化的关系

本文阐述了右江裂谷区微细粒浸染型金矿床控矿层位三叠系百蓬组泥质粉砂岩及砂质泥岩的粒度，比表面、孔隙度及孔隙类型和渗透率等物性特征，讨论了与其成矿流体的循回、水岩反应及其有效浸取围岩矿物质的关系。在此基础邮成矿流体和矿矿物质主要来自于地层；由于热液躲避低势能方向迁移，造成断理解发的盆地边缘区和水下隆起周围的环状断裂带为金矿床沉淀的场所。并通过形成金矿所需热液量的估算得出，该区金矿床的形成，是由于热流     

世界主要深水含油气盆地烃源岩特征

对墨西哥湾、巴西东部大陆边缘、西非被动大陆边缘、澳大利亚西北陆架、挪威中部陆架、南海等六个地区的22个深水含油气盆地烃源岩特征(主力烃源岩形成的时代、构造背景、沉积环境、类型、地球学化指标等)的综合研究结果表明,世界深水含油气盆地主力烃源岩主要集中在白垩系,其次为第三系和侏罗系;裂谷期烃源岩占绝对优势,其次为被动陆缘期...     

卧龙湖煤矿102工作面顶板采动效应研究

基于卧龙湖煤矿的岩石力学测试资料,运用FLAC3D数值模拟软件,分析了102工作面在回采过程中的应力重分布、覆岩的变形和破坏特征。数值模拟结果表明,随着工作面的向前推进,垂直方向应力和位移成增加的趋势,采空区中间部位岩体位移近于垂直方向。研究结果为工作面布置方法、顶板支护方式的选择和采区设计提供了依据,为顶板事故的预防提供了参考资料。