“Transverse Action” – A model benchmark exercise for numerical analysis of the Callovo-Oxfordian claystone hydromechanical response to excavation operations     

《Computers and Geotechnics》2017

The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive models have been developed/used in the framework of the R&D and simulation programs of Andra. A model benchmark exercise has been launched since 2012 to provide an overall view of the developed models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.  相似文献   

中酸性隐爆角砾岩型金属矿床稀土元素地球化学特征          下载免费PDF全文

梁俊红  巩恩普  姚玉增  崔显德 《地质找矿论丛》2011,26(1):23-27,50

与火山、次火山隐爆作用有关的中酸性隐爆角砾岩型矿床是一种重要的矿床类型.中酸性隐爆角砾岩型金、银-金、铀、钨-钼-铜-铅-锌典型矿床的矿石、蚀变围岩稀土元素研究表明,不同矿种的矿床稀土元素地球化学具有极强的相似性和弱差异性.矿床稀土元素总量w(REE)=69.7×10-6～245.27×10-6,单个矿床稀土元素总量变...  相似文献   

泥岩弹塑性损伤本构模型及其参数辨识   总被引：2，自引：1，他引：1  

贾善坡  陈卫忠  于洪丹  李香玲 《岩土力学》2009,30(12):3607-3614

以连续介质力学和不可逆热力学为基础,将损伤引入到修正的Mohr-Coulomb准则中,建立了泥岩弹塑性损伤本构模型反映泥岩软硬化行为,通过构建损伤势函数导出了泥岩的损伤演化方程,编制了泥岩弹塑性损伤本构模型及其参数反演程序。并根据非排水条件下泥岩三轴试验结果,采用多目标函数优化反分析法获得了泥岩本构模型参数。研究成果表明,所提出的弹塑性损伤本构模型能有效地描述泥岩在不同应力状态下的力学特性。  相似文献   

Smectite formation in metalliferous sediments near the East Pacific Rise at 13°N   总被引：1，自引：0，他引：1  

荣坤波  曾志刚  殷学博  陈帅  王晓媛  齐海燕  马瑶 《海洋学报(英文版)》2018,37(9):67-81

A 43 cm long E271 sediment core collected near the East Pacific Rise(EPR) at 13°N were studied to investigate the origin of smectite for understanding better the geochemical behavior of hydrothermal material after deposition.E271 sediments are typical metalliferous sediments. After removal of organic matter, carbonate, biogenic opal,and Fe-Mn oxide by a series of chemical procedures, clay minerals(2 μm) were investigated by X-ray diffraction,chemical analysis and Si isotope analysis. Due to the influence of seafloor hydrothermal activity and close to continent, the sources of clay minerals are complex. Illite, chlorite and kaolinite are suggested to be transported from either North or Central America by rivers or winds, but smectite is authigenic. It is enriched in iron, and its contents are highest in clay minerals. Data show that smectite is most likely formed by the reaction of hydrothermal Fe-oxyhydroxide with silica and seawater in metalliferous sediments. The Si that participates in this reaction may be derived from siliceous microfossils(diatoms or radiolarians), hydrothermal fluids, or detrital mineral phases. And their δ30 Si values are higher than those of authigenic smectites, which implies that a Si isotope fractionation occurs during the formation because of the selective absorption of light Si isotopes onto Feoxyhydroxides. Sm/Fe mass ratios(a proxy for overall REE/Fe ratio) in E271 clay minerals are lower than those in metalliferous sediments, as well as distal hydrothermal plume particles and terrigenous clay minerals. This result suggests that some REE are lost during the smectite formation, perhaps because their large ionic radii of REE scavenged by Fe-oxyhydroxides preclude substitution in either tetrahedral or octahedral lattice sites of this mineral structure, which decreases the value of metalliferous sediments as a potential resource for REE.  相似文献   

东太平洋海隆13°N表层含金属沉积物物质组成与元素赋存状态     

荣坤波  曾志刚  武力  李康 《海洋科学》2018,42(7):70-79

为了解不同类型含金属沉积物在物质组成和元素赋存状态的差异,对东太平洋海隆13°N洋中脊两侧表层含金属沉积物(站号:E271和E53)进行了矿物学、地球化学分析,顺序提取实验,并与前人对轴部表层沉积物(站号:17A-EPR-TVG1)的研究结果作了对比分析。研究结果表明, E271和E53是远端含金属沉积物,由非浮力热液羽状流中颗粒物沉降所形成的;17A-EPR-TVG1沉积物是近喷口含金属沉积物,由黑烟囱或者热液硫化物丘状体崩塌、堆积,或者由热液羽状流中Fe-Mn氧化物和硫化物快速沉淀而形成的,近喷口沉积物比远端沉积物更富集Fe、Cu和Zn等元素。元素在两种含金属沉积物中的赋存状态基本相同,除了Fe,Cu,Zn,Mo和稀土元素(REE)等元素在远端沉积物中主要存在于Fe-Mn氧化物相,在近喷口沉积物中主要在残留相中。远端沉积物中REE页岩标准化配分模式与海水相似,表明REE主要来自海水,而近喷口沉积物中REE配分模式与热液流体相似,说明REE以高温热液流体来源为主。相关研究结果加深了对热液沉积作用研究的认识。  相似文献   

贵州西部氟中毒地区氟来源地质背景研究   总被引：1，自引：0，他引：1       下载免费PDF全文

王尚彦  刘家仁 《沉积与特提斯地质》2006,26(3):72-76

贵州省西部广泛分布上二叠统煤系地层,燃煤型氟中毒严重影响当地居民的身体健康。引起氟中毒的氟是多来源的,影响氟中毒的因素是多方面的。高氟含量的岩石粘土岩、煤、页岩等是氟的初始来源体;高氟含量土壤是氟第二个层次的来源;高氟含量土壤中种植的农作物是第三个层次的来源;燃煤烟尘直接排放室内空气中和用燃煤烘烤食物等,使空气、食物和水中氟含量增高,是一重要的人为氟来源。人通过呼吸高氟含量的空气和食(饮)用高氟含量的食物(水)将氟沉淀在体内,造成氟中毒。  相似文献   

大同塔山煤矿粘土岩的特征及成因   总被引：1，自引：0，他引：1  

何仕 《中国煤田地质》2006,18(3):23-25

本文在对塔山煤矿的矿井概况和区域构造背景介绍的基础上，阐明了塔山煤矿煤系地层粘土资源的分布特征，对形成粘土岩的物质来源和成因类型进行了探讨，指明了塔山煤矿煤系地层中的粘土矿物主要是以沉积作用为主的高岭石粘土岩，其次是火山喷出物质在水介质中经蚀变作用和风化残积物在海水碱性介质中，由于地球化学分凝作用再沉积而成，最后总结了塔山煤矿主要粘土矿物——高岭石的形成条件。  相似文献   

矿井粘土岩特性及其对巷道稳定性的影响   总被引：2，自引：0，他引：2  

崔龙鹏  朱国维 《岩土力学》1998,19(4):52-56

在分析龙口矿区2号煤层顶底板粘土岩的物质组成、微结构和物化特性的基础上,讨论了粘土岩的膨胀特性对巷道稳定性的影响,进而指出了本研究在巷道工程应用中的意义。  相似文献   

河南某地粘土矿中锂绿泥石的发现及初步研究   总被引：1，自引：1，他引：1  

沈丽璞  宋云华  彭昭瑞  郭可战 《矿物学报》1986,(1)

本文将粘土岩中含锂最高(Li_2O——1.76%)的16号样品分成八个粒级,采用X射线粉晶照相、X射线粉末衍射,红外吸收光谱、差热、化学全分析、透射和扫描电镜以及质子核磁共振和顺磁共振等手段,对其进行了较详细的研究。结果表明,样品主要由结晶较好的细粒锂绿泥石组成,含少量的伊利石。经计算得锂绿泥石的化学式为: (Li_(0.68) Ca_(0.01) Na_(0.01))_0.70 (Al_(3.85) Mg_(0.09) Fe_(0.05)~(2+) Fe_(0.01)~(3+))_4 (Si_(3.11)Al_(0.89)O_(10))(OH)_8利用X射线衍射强度估算,锂绿泥石在全岩中的含量约为85.1%,因而该样品可称做锂绿泥石粘土岩。根据锂绿泥石的共生组合和化学组成,结合显微镜下鉴定结果,推断本区锂绿泥石是伊利石在成岩作用中于较适宜的条件下转变来的。  相似文献   

Manganese metalliferous sediments of the Deryugin Basin (Sea of Okhotsk): Chemical composition and geological setting     

A. S. Astakhov  V. V. Sattarova  A. I. Svininnikov  N. V. Astakhova  M. M. Domanov  M. V. Ivanov 《Russian Journal of Pacific Geology》2007,1(5):418-434

This paper reports the results of an investigation of the chemical composition and distribution of manganese-rich metalliferous sediments in the Deryugin Basin. They compose an upper sedimentary layer up to 30 cm thick within a strip up to 40 km wide and 180 km long in the central part of the basin along the East Deryugin suture zone bounding the Deryugin sedimentary basin to the east. The sediments are enriched relative to the regional background composition in Mn (by a factor of 35); Au; Ni; Zn; Co (by a factor of 3–5); and, locally, in Mo, V, Ba, Cu, Pb, and Hg. It was supposed that their formation was controlled by several processes: precipitation of Mn and some other trace elements from hydrothermal plumes of seawater that occasionally form above submarine hot vents in the northern part of the basin, precipitation from anoxic bottom waters at the eastern boundary of the Deryugin sedimentary basin, and early diagenetic migration of Mn into the surface sediments.  相似文献