松辽盆地北部含铀岩系沉积物源及铀源分析研究进展

笔者在开展松辽盆地北部砂岩型铀矿地质调查时,系统收集了松辽盆地北部沉积物源、铀源的基础资料,对松辽盆地北部主要含铀岩系物源体系研究进展进行了概括和总结:1)目前沉积物源研究主要针对含油气目的层展开,而具重要铀成矿潜力的层位如上白垩统四方台组、明水组研究甚少;2)盆地北部各沉积时期物源具有明显的不均匀性,传统物源分析方法得出的结论尚存在诸多分歧,需加强碎屑锆石U-Pb定年等新兴技术手段的应用.对松辽盆地北部铀源条件研究现状进行了系统论述:1)松辽盆地北部具有良好的蚀源区供铀条件,岩体铀含量较高,活化迁移明显,铀镭平衡系数表明了沉积盖层中存在铀的原始预富集和后生活化迁移;2)针对沉积盖层原始铀含量的计算和空间上活化铀迁移规律的研究略显不足,同时缺乏“双重供铀”模式的认识,应加强铀预富集方面的研究.物源和铀源及二者的源-汇过程与含铀岩系沉积环境研究关系密切,同时严重制约了铀矿床的产出,对其精确厘定有助于深入理解砂岩型铀矿的局部预富集作用,并对砂岩型铀矿有利成矿区段进行合理的预测和评价.     

砂岩型铀矿蚀变矿物研究中的岩心光谱扫描技术

以松辽盆地典型砂岩型铀矿钻孔岩心归档资料为基础,系统总结了岩心光谱扫描技术在砂岩型铀矿中的应用流程,并在前人光谱强度与矿物含量研究的基础上,补充开展了不同时间域的矿物扫描结果对比.研究结果表明,岩心光谱扫描技术能快速、有效地提取岩心中的蚀变矿物空间分布信息,开展蚀变矿物填图,包括常见的粘土矿物、硫酸盐矿物、碳酸盐矿物和Fe2-氧化物等;沉积岩长期放置带来的风化作用对光谱数据的影响主要反映在蚀变矿物的整体含量变化上,对蚀变矿物种类未产生明显变化;利用岩心光谱扫描技术完成的蚀变矿物填图,获取的宏观蚀变矿物及其组合变化对砂岩型铀矿地层划分、氧化还原分带、成矿流体特征反演和矿床勘查等具有重要意义,应用前景广阔.     

贵州省避暑旅游气象适宜性分析

参照避暑旅游气候适宜度评价方法,以体感温度确定的避暑旅游气象舒适度为正贡献指标,修正完善强降水、高温、大风、雷暴等负贡献的高影响天气指标,综合建立避暑旅游气象适宜度评价模型.选取2008—2017年6—8月地面气象要素观测资料,利用该避暑气象适宜度模型对贵州省县级以上城市避暑旅游适宜性进行分析.结果表明:贵州整体上是非...     

青海省贵德国家地质公园地质遗迹及综合评价

地质遗迹综合评价是保护和利用地质遗迹的重要科学依据.本文在系统阐述青海省贵德国家地质公园地质遗迹类型与特征的基础上,依据国土资源部《中国国家地质公园建设技术要求和工作指南》地质遗迹(景观)评价系统和改进后的菲什拜因-罗森伯格模型,对贵德国家地质公园地质遗迹进行综合评价研究.结果表明:公园地质遗迹丰富多样、形态典型、景观奇特、保存良好;地质遗迹可分为8个大类,16个亚类;地质遗迹具有较高的科学价值、科普价值、美学价值、康体价值以及旅游开发价值,其中尤以水体景观、峰丛地貌和黄河奇石最为典型,属于国家级资源.研究结果不仅为地质遗迹的评价提供了一种新的模式,而且对于正确认识贵德国家地质公园地质遗迹状况,深入进行地质遗迹保护、开发利用和管理等工作具有一定的参考价值.     

剪褶皱的特征及其成因分析

剪褶皱（Shear fold）,或称滑褶皱（Slip fold）,在国内外教科书及地质词典等文献中均有介绍。这个概念是Spitz于1911年引入的。W.carey于1962年用一组卡片模拟剪褶皱作用,该模式至今仍被广泛应用,如D.M.Ragan（1973）（图1）、B.E.Hobbs（1975）、武汉地院等四院校合编的构造地质学（1979）等等。许多研究者认为剪褶皱是,岩层沿着     

中国深层煤层气勘探开发进展、关键评价参数与前景展望

经过30 a的不懈探索,我国煤层气开发井型逐渐由直井向水平井开发过渡,水平井开发煤层气的基础理论是制约当前煤层气开发的主要问题。和页岩相比,煤层页理和脆性矿物不发育,非均质性更强,不利于体积缝网的形成。但煤层顶底板封盖强,机械强度高,具备较好的水力压裂条件。部分煤层裂隙被方解石等填充,酸化有利于储层渗透率改善和复杂裂缝形成。因此,建立一套适合煤层气储层特征的水平井开发工艺尤为重要。针对煤层地质特征,从水平井长度优化、簇间距优化、压裂液选择、支撑剂选择、返排率、最终可采储量(EUR)特征6个方面,系统分析煤层气水平井开发技术经济政策,认为煤层气水平段长度一般不超过1 000 m,簇间距15~30 m储层改造效果较好;深部煤层气压裂液中加入滑溜水破胶剂及少量低温辅助破胶剂可提高破胶效率;相比中浅部煤层气储层,深部煤层压裂支撑剂应提高大粒径(0.425/0.850 mm)比例;深部煤层(如大吉区块8号煤)达到最高产气时的压裂液返排率与威远−长宁页岩气相近;煤层气EUR偏低,但用液强度、加砂强度大,应提高煤层气开发效率及经济效益等。煤层气开发效果受地质特征和开发工程技术协同控制,从地质工程一体化角度,提出下步煤层气水平井开发的对策,指出应进一步优化煤层气水平井开发工艺;完善水平井钻完井与配套技术,降低单井钻完井成本;依据煤粉迁移规律,实现煤层气水平井控粉有序返排,提高排采效果;依据游离与吸附气赋存比例,优化生产控制技术提升单井EUR。

     

Discrete element analysis of the influence of bolt pattern and spacing on the force-displacement response of bolted steel mesh

Steel wire mesh held by a pattern of bolts can be used to stabilize a rock slope. Knowledge of the force-displacement response of steel mesh is essential in the design of this support system. Laboratory tests have been used to test mesh that is held to rigid steel frames. These testing conditions differ from how steel mesh is held in the field by bolts. The existing laboratory test data may underestimate the deformation and overestimate the load-bearing capacity of the steel mesh. This paper focuses on the response of the high tensile strength steel mesh held by commonly used bolt patterns. Discrete element models were used to study the force-displacement response of the steel mesh pinned by bolts. The influences of different bolt patterns and varying ratios of bolt spacing on the effectiveness of steel wire mesh were analyzed. Relationships between the resistance force of steel mesh and bolt density at various mesh deformations were developed. These relationships can help engineers choose the bolt spacing and provide an estimate of the resistance force that a steel mesh can mobilize at a desired deformation limit for a given bolt pattern.     

Influence of a point sink on a pile group in saturated multilayered soils with anisotropic permeability

The behavior of a pile group is solved using the finite element method, and the fundamental solution of saturated multilayered soils with anisotropic permeability is obtained by the analytical layer element method. Based on the supposition of no slip occurring at the pile‐soil interface, the governing equations of the interaction between the pile group and the soils due to a point sink are established in the Laplace‐Hankel transformed domain by considering the pile‐soil compatibility condition. Numerical results are presented to study the effect of point sink pumping, the properties of soils, and the geometries of piles on the behavior of the pile group.     

Assessing the effects of the Three Gorges Dam and upstream inflow change on the downstream flow regime during different operation periods of the dam

As the largest hydroelectric dam in the world, the Three Gorges Dam (TGD) has raised wide concerns over the environmental and ecological impacts since its dramatic effect on the downstream flow regime of the Yangtze River. Since 2003, the TGD has progressed from the initial operation period to the full operation period, with different effects on the downstream flow regime over each period. Although the upstream inflow change (USIC) of the TGD is a possibly additional factor affecting the downstream flow regime, this has drawn little attention. This study aims to quantify the individual contributions of the TGD and the USIC to the changes of the downstream flow regime over different operation periods of the dam. Using the Muskingum routing model and the Xin'anjiang rainfall–run‐off model, we reconstruct the discharge unregulated by the TGD for the post‐TGD period from 2003 to 2015. On this basis, the effects of the TGD and the USIC on the downstream flow regime are quantitatively assessed. Benchmarked against the flow regime during the pre‐TGD period from 1955 to 2002, it is found that the TGD and the USIC play considerable and comparable roles in affecting the downstream flow regime during the whole post‐TGD period from 2003 to 2015. Furthermore, the TGD appears to have a limited effect on the downstream flow regime during the initial operation period from 2003 to 2008 relative to the USIC. In contrast, during the full operation period from 2009 to 2015, the TGD plays a dominant role in changing the downstream flow regime, although the effect of the USIC cannot be neglected. The findings of this study are helpful to understand the exact impacts of the TGD on the downstream flow regime, thereby facilitating the development of a rational strategy for operating the dam.     

面向地理国情监测的变化检测与地表覆盖信息更新方法

常态化地理国情监测能够全面、动态地掌握地理国情信息及其变化,为经济建设和社会发展提供数据基础。地理国情普查成果是按照统一规范标准、经过内业解译和外业核查形成的矢量数据。如何在普查成果的基础上,利用多时相遥感影像实现变化信息提取与更新是地理国情监测的关键。针对地理国情普查成果的特点与监测需求,以多时相遥感影像处理分析为基础,构建了针对地理国情监测的变化检测方法体系,提出了像元—对象结合的多时相影像变化检测、基于对象实体统计分析的变化识别方法,实现了综合地理国情普查成果和遥感影像的地理国情变化检测与数据更新。基于像元—对象结合的多时相影像变化检测首先根据传统的变化矢量分析法提取基于像元的变化检测结果,再以地理国情普查的矢量对象为统计单元计算对象内变化像元的比例,以此判断该矢量对象是否发生了变化,并根据变化像元的比例计算其变化强度。基于对象实体统计分析的变化检测方法直接以地理国情矢量为对象进行特征提取和差异构造,再将差异影像进行阈值分割得到基于地理国情对象的变化检测图。最后,根据变化检测结果,对变化区域进行面向对象分割,并从上一期未变化区域选取训练样本训练分类器模型以得到变化区域的地表覆盖类型,将变化区域与未变化区域结合得到更新后的地理国情矢量图。选取江阴市地理国情普查成果和两期高分辨率遥感影像进行试验,结果表明本文提出的方法在准确提取和解释变化区域的同时,明显提高了变化检测和数据更新的效率,可用于常态化地理国情监测。