小流域水沙耦合模拟概念模型*

小流域水沙耦合模拟概念模型,采用文献[1]、[2]和[4]中提出的概念性坡面产沙、沟蚀产沙、坡面汇沙、沟道汇沙和格林-安普特下渗曲线结构,结合水文学中的概念性汇流计算方法,构成了一个完整的、具有明确物理意义的流域水流、泥沙耦合模拟模型.该模型结构简单,经子洲试验站团山沟三试验场和蛇家沟、团山沟、水旺沟三试验小流域实测资料的模拟检查表明,模型结构合理、效果较好,适合于黄土地区流域.     

对1954年民勤7级地震的初步研究

较系统地研究了１９５４年民勤７级地震的宏观震中、震区烈度分布及地质构造背景等问题,并圈定了极震区范围,根据调查结果认为,该次地震是由于红崖山－四道山断裂在ＮＥ向或ＮＮＥ向主压应力作用下,发生左旋斜冲向东端扩张破裂的结果,与ＮＮＷ向构造带的复合也有一定的关系。     

Hydraulics of sediment-laden sheetflow and the influence of simulated rainfall

Laminar sheetflows, transporting sediment at their capacity rates, both with and without rainfall disturbance, were investigated. Values of flow depth and relative submergence were very small. In the flows without rainfall, measured velocities exceeded the predictions of the smooth-surface, clear-water laminar model by an average of 12 per cent. Reduced flow resistance due to high sediment concentrations may explain this result. Velocities in the rainfall-disturbed flows were not significantly different from the predictions of the smooth-surface, clear-water model, and the velocity reduction due to rainfall was about 12 per cent. Although the uniformity of rainfall intensity under the single-nozzle rainfall simulator is high, variation of momentum and kinetic energy fluxes along the 1-5 m long flume was significant. The rainfall angle of incidence was highly correlated with deviations from expected flow velocities in the upper and lower sections of the flume.     

WINDOW FACTOR ANALYSIS:THEORETICAL DERIVATION AND APPLICATION TO FLOW INJECTION ANALYSIS DATA

Window factor analysis(WFA)is a self-modeling method for extracting the concentration profiles ofindividual components from evolutionary processes such as flow injection,chromatography,titrationsand reaction kinetics.The method takes advantage of the fact that each component lies in a specificregion along the evolutionary axis,called the‘window’.Theoretical equations are derived.The methodis used to extract the concentration profiles and spectra of seven bismuth species from data obtained byGemperline and Hamilton,who injected bismuth perchlorate into a flowing stream of hydrochloric acid.     

利用地基土应力分布原理确定砂垫层厚度

软弱土层场地若采用天然地基不能满足建筑物所需强度与沉降要求,采用换土撼砂法就可以提高地基的承载力。运用应力分布原理合理确定撼砂层厚度不仅可保证工程稳固性,并可节约投资和缩短工期。     

基于物质流分析的区域循环经济评价指标体系构建——以陕西省榆林市为例

以物流分析为基础,兼顾循环经济的3R原则,利用循环经济发展中涉及的物质流分析指标,以及物质流指标与人、经济、单位投入、产出等外延领域的结合衍生指标构建循环经济评价指标体系,并对各指标作了解释,对数据来源途径做了分析.     

Influence of rainfall on the deformation and stability of a slope in overconsolidated clays: a case study

The behaviour of an instrumented unstable slope in a profile of weathered overconsolidated clay has been analysed. Available field investigation data and laboratory tests were integrated in a coupled hydromechanical model of the slope. Particular attention was given to the unsaturated soil conditions above the water table and to the influence of the rainfall record. Recorded pore-water pressures helped to identify the hydrogeological conditions of the slope. The coupled model was used to compute slope deformations and the variation of safety with time. Actual rainfall records were also integrated into the analysis. Comparison of measurements and calculations illustrate the nature of the slope instability and the complex relationships between mechanical and hydraulic factors. Electronic Publication     

Faulting, fracturing and in situ stress prediction in the Ahnet Basin, Algeria — a finite element approach

Many low-efficiency hydrocarbon reservoirs are productive largely because effective reservoir permeability is controlled by faults and natural fractures. Accurate and low-cost information on basic fault and fracture properties, orientation in particular, is critical in reducing well costs and increasing well recoveries. This paper describes how we used an advanced numerical modelling technique, the finite element method (FEM), to compute site-specific in situ stresses and rock deformation and to predict fracture attributes as a function of material properties, structural position and tectonic stress. Presented are the numerical results of two-dimensional, plane-strain end-member FEM models of a hydrocarbon-bearing fault-propagation-fold structure. Interpretation of the modelling results remains qualitative because of the intrinsic limitations of numerical modelling; however, it still allows comparisons with (the little available) geological and geophysical data.

In all models, the weak mechanical strength and flow properties of a thick shale layer (the main seal) leads to a decoupling of the structural deformation of the shallower sediments from the underlying sediments and basement, and results in flexural slip across the shale layer. All models predict rock fracturing to initiate at the surface and to expand with depth under increasing horizontal tectonic compression. The stress regime for the formation of new fractures changes from compressional to shear with depth. If pre-existing fractures exist, only (sub)horizontal fractures are predicted to open, thus defining the principal orientation of effective reservoir permeability. In models that do not include a blind thrust fault in the basement, flexural amplification of the initial fold structure generates additional fracturing in the crest of the anticline controlled by the material properties of the rocks. The folding-induced fracturing expands laterally along the stratigraphic boundaries under enhanced tectonic loading. Models incorporating a blind thrust fault correctly predict the formation of secondary syn- and anti-thetic mesoscale faults in the basement and sediments of the hanging wall. Some of these faults cut reservoir and/or seal layers, and thus may influence effective reservoir permeability and affect seal integrity. The predicted faults divide the sediments across the anticline in several compartments with different stress levels and different rock failure (and proximity to failure). These numerical model outcomes can assist classic interpretation of seismic and well bore data in search of fractured and overpressured hydrocarbon reservoirs.     

Dynamics of an active rock glacier (Ötztal Alps, Austria)

The rock glacier Innere Ölgrube, located in a small side valley of the Kauner Valley (Ötztal Alps, Austria), consists of two separate, tongue-shaped rock glaciers lying next to each other. Investigations indicate that both rock glaciers contain a core of massive ice. During winter, the temperature at the base of the snow cover (BTS) is significantly lower at the active rock glacier than on permafrost-free ground adjacent to the rock glacier. Discharge is characterized by strong seasonal and diurnal variations, and is strongly controlled by the local weather conditions. Water temperature of the rock glacier springs remains constantly low, mostly below 1°C during the whole melt season. The morphology of the rock glaciers and the presence of meltwater lakes in their rooting zones as well as the high surface flow velocities of >1 m/yr point to a glacial origin. The northern rock glacier, which is bounded by lateral moraines, evolved from the debris-covered tongue of a small glacier of the Little Ice Age with its last highstand around A.D. 1850. Due to the global warming in the following decades, the upper parts of the steep and debris-free ice glacier melted, whereas the debris-covered glacier tongue transformed into an active rock glacier. Due to this evolution and due to the downslope movement, the northern rock glacier, although still active, at present is cut off from its ice and debris supply. The southern rock glacier has developed approximately during the same period from a debris-covered cirque glacier at the foot of the Wannetspitze massif.     

层滑构造煤岩体微观特征及其应力应变分析

层滑构造在煤层及其顶、底板间普遍发育,它对地质勘探、煤矿生产、矿井工程灾害防治以及煤层气的开发等方面都有着重要影响。本文以淮北煤田海孜煤矿为例,在研究宏观层滑构造带组合特征的基础上,探讨了层滑构造的微观特征和形成机理。构造煤是层滑引起的煤层流变最显著的特征之一。通过对构造煤与构造岩的微观特征测试,发现层滑运动除了产生脆性变形外,还产生较强烈的塑性变形。利用煤镜质组光率体各向异性和构造岩组构,结合层滑构造的实测数据进行了煤岩体应力、有限应变分析。结果表明:层滑构造以顺层剪切为主,煤层受力的主要方向为NW-SE向。