Modelling of deformation response and chemo‐mechanical coupling in chalk     

S. Pietruszczak  D. Lydzba  J. F. Shao 《国际地质力学数值与分析法杂志》2006,30(10):997-1018

A constitutive relation is derived for describing the mechanical response of chalk. The approach is based on a phenomenological framework which employs chemo‐plasticity. The properties of the material are assumed to be affected by the physico‐chemical processes that occur through the interaction between the skeleton and the pore fluid. The underlying mechanism is discussed by invoking a micromechanical analysis. The performance of the framework is illustrated by examining the evolution of mechanical characteristics in the presence of different pore fluids. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

A transdisciplinary analysis of water problems in the mountainous karst areas of Morocco     

C. de Jong  S. Cappy  M. Finckh  D. Funk 《Engineering Geology》2008,99(3-4):228

Water management and engineering in the karstic High Atlas of Morocco are difficult tasks under the prevailing geological, hydrogeological, geomorphological, vegetational and climatic conditions. It is important to be able to understand and predict the characteristics and availability of water for future water planning in the region under changing climatic and agricultural conditions. An interdisciplinary analysis of problems and adequate hydrological modelling tools developed by geologists, hydrologists and biologists are necessary. The karst areas of the High Atlas Mountains are characterised by impermeable triassic basalt underlying substantial subsurface reservoirs with high potential discharge rates. The karst groundwater aquifers are extensive but largely unknown in dimension, probably with a hierarchical network of groundwater flow paths. It is estimated that approximately 70% of the surface water is directly lost to groundwater. Steep landslide- and debris flow prone slopes exist next to coarse-grained, highly porous river beds. Infrequent, high intensity rainfall or snowmelt causes a particularly high flood risk to these karst areas. In addition, agriculture and land use changes have degraded the karst areas. The most important driving forces for degradation include permanent overgrazing even during droughts and the use of firewood by a continually growing population. Large scale degradation of vegetation has occurred in the oro-mediterranean (mountainous Mediterranean) zone, between 2600 and 3400 m which coincides with the most important zone for karstic groundwater creation. The combination of high amounts of groundwater flow and rapid surface flow due to sparse vegetation has increased the problems of flood flow.  相似文献   

Influence of Structural Non-Stationarity of Surface Roughness on Morphological Characterization and Mechanical Deformation of Rock Joints   总被引：2，自引：2，他引：0  

N. Fardin 《Rock Mechanics and Rock Engineering》2008,41(2):267-297

Summary Structural non-stationarity of surface roughness affects accurate morphological characterization as well as mechanical behaviour of rock joints at the laboratory scale using samples with a size below the stationarity threshold. In this paper, the effect of structural non-stationarity of surface roughness is investigated by studying the scale dependence of surface roughness and mechanical behaviour of rock joints. The results show that the structural non-stationarity mainly affects the accurate characterization of the surface roughness of the fracture samples. It also controls the amount and location of the contact areas during shear tests, which in turn affects the mechanical properties and asperity degradation of the samples. It is concluded that for accurate determination of the morphological and mechanical properties of rock joints at laboratory and field scales, samples with size equal to or larger than the stationarity threshold are required. Author’s address: Nader Fardin, Rock Mechanics Group, Department of Mining Engineering, Faculty of Engineering, University of Tehran, P.O. Box: 11365/4563, Tehran, Iran  相似文献   

中国海岸湿地退化压力因素的综合分析   总被引：39，自引：1，他引：39       下载免费PDF全文

谷东起  赵晓涛  夏东兴 《海洋学报》2003,25(1):78-85

对我国海岸湿地类型、特点和分布进行了论述.通过分析指出围垦、城市与港口开发、污染、海岸侵蚀、油气资源开发、生物资源过度利用和海平面上升等环境压力因素是造成湿地退化的主要原因.综合矩阵因子分析表明,不同的海岸湿地类型所承受的环境压力和所遭受的环境退化程度是不同的,其中三角洲、海岸潟湖、砂质海岸、珊瑚礁、淤泥质海岸、滨岸沼泽和红树林等湿地类型遭受的环境压力最大,环境退化也最严重;指出了人为因素是造成海岸湿地环境退化的主要原因.  相似文献   

海洋中的烃及其迁移和衰变   总被引：3，自引：0，他引：3  

崔仙舟  尹相淳 《海岸工程》1995,14(4):25-32

对海洋中有关烃类的研究工作进行回顾和总结，分别介绍海洋中烃的来源，迁移和衰变及石油对海洋的污染。  相似文献   

唐山市滨海湿地动态演变特征及其机制分析     

邱若峰  杨燕雄  刘松涛  周振祥  孙娟 《海洋湖沼通报》2006,(4):25-31

利用历史资料和Landsat TM卫星遥感图像,研究了唐山市滨海湿地自建国以来的演变特征,着重对1987~2004年陡河———滦河之间的滨海平原湿地类型进行了识别,绘制了不同时期的景观面解译图。利用Mapinfo制图软件计算出两个时期的面积(比例)转化矩阵,显示该区滨海湿地破碎化加重,其动态演变特征呈明显退化趋势,进而提出引起其退化的原因和发展趋势预测。  相似文献   

基于RS和GIS的唐山沿海地区湿地结构动态监测     

汪高明  邱若峰  SUN Xiaogong 《海洋湖沼通报》2007,(3):35-40

利用历史资料和Landsat TM卫星遥感图像,研究了唐山市沿海地区湿地结构自上世纪80年代以来的演变特征,着重对1987~2004年陡河——滦河之间的湿地结构类型进行了识别,绘制了不同时期的湿地面积解译图。利用Mapinfo制图软件计算出两个时期的面积转化矩阵,对该区主要湿地类型浅海水域、滩涂、芦苇沼泽、水稻田、养殖场、盐田等湿地的面积进行了年份比较,从而分析得出唐山市沿海湿地结构从80年代至今以来破碎化加重,应该加强湿地结构的动态监测。  相似文献   

Mussel Periostracum from Deep-Sea Redox Communities as a Microbial Habitat: 3. Secondary Inhabitants     

James E.  Hook Stjepko  Golubic 《Marine Ecology》1992,13(2):119-131

Abstract. Vacated microborings in periostracum of live mussels of the Florida Escarpment redox community (depth of 3266 m) become a habitat for a prolific secondary microbiota consisting of a variety of prokaryotic and a few eukaryotic organisms. Periostracum surface is also colonized by diverse microorganisms, dominated by presumed chemolithotrophic bacteria with stacks of intracellular lamellae. Unlike sheltered microflora within borings, the surface community is heavily grazed upon by numerous archaeogastropods and ciliates.  相似文献   

邻苯二甲酸二甲酯及其异构体的好氧微生物降解   总被引：3，自引：0，他引：3  

李魁晓  顾继东 《热带海洋学报》2006,25(1):51-55

3种苯二甲酸二甲酯异构体(邻、间和对苯二甲酸二甲酯)主要应用于化学工业,作为增塑剂和生产聚酯的原料。用邻苯二甲酸二丁酯为惟一碳源,从红树林底泥中驯化、富集、培养、分离得到的微生物对邻苯二甲酸二甲酯(Dimethylphthalate,DMP)及其异构体对苯二甲酸二甲酯(Terephthalate,DMT)和间苯二甲酸二甲酯(Isophthalate,DMI)具有较强的降解作用。此菌株16SrDNA分子生物学的鉴定为Rhodococcusruber1k。实验得出该菌能够在苯二甲酸二甲酯作为惟一碳源和能源的培养基中生长。浓度为50mg·L-1的DMP、DMI和DMT分别在6、10、11d内可以完全被降解;DMP能够在好氧条件下被该菌快速降解,生成邻苯二甲酸一甲酯(monomethylphthalate,MMP)和邻苯二甲酸(phthalicacid,PA)2种主要中间产物,最终可以完全矿化成CO2和H2O;该菌对DMI和DMT的降解速度则比DMP慢。两者的降解中间产物间苯二甲酸一甲酯(MMI)和对苯二甲酸一甲酯(MMT)却不能被Rhodococcusruber1k继续降解而在培养基中积累。结果表明苯二甲酸二甲基酯的3种异构体能够被红树林底泥中的土著微生物降解。降解速度及降解途径与底物的化学结构有密切关系。  相似文献   

红枫湖夏季分层期间pCO₂分布规律的研究   总被引：4，自引：0，他引：4       下载免费PDF全文

吕迎春  刘丛强  王仕禄  徐刚 《水科学进展》2008,19(1):106-110

在夏季分层期间对红枫湖南、北湖湖心的水样进行分层采集,同时测定了分层水样的温度、pH、HCO₃-浓度、溶解氧(DO)、叶绿素a(Chl-a)及铵根离子(NH₄+)、硝酸根离子(NO₃-)、磷酸根离子(PO₄3-)的浓度,水体中CO₂的分压(pCO₂)由化学平衡及亨利定律求得。研究结果表明:光合作用、有机质降解及水体热分层是影响红枫湖夏季pCO₂分布的主要因素。其中,温水层CO₂欠饱和是光合作用吸收CO₂引起的,温跃层中pCO₂的急剧增加是光合产物降解产生CO₂引起的。静水层沉积物附近pCO₂最高并且还有持续增加的趋势,说明沉积物中有机质降解是静水层中CO₂增加的主要原因,夏季湖底水温较高加快了沉积物中有机质的降解。分层现象使pCO₂在水体中的分布差别明显,并且使静水层中CO₂得到积累。此外,夏季红枫湖水体中pCO₂的变化与NH₄+、PO₄3-的变化密不可分,表现为温水层中光合作用消耗NH₄+、PO₄3-,有机质降解过程伴随NH₄+、PO₄3-的释放。  相似文献