重力、航磁资料在花岗岩型铀矿成矿研究中的应用

本文利用重磁场资料对我国南方一些花岗岩体的侵位状态和岩浆动力场进行了分析，并按动力场的强弱对岩体进行了分类。根据重力资料对苗儿山-越城岭、诸广山和贵东花岗岩体的反演计算，讨论了这些岩体的深部分布形态，提出了岩浆流动的3种方式，指出了富大铀矿床、大型铀矿聚集区的赋存部位及其与航磁异常的密切联系。     

水流模拟智能化问题的探讨

对水流模拟的发展历史进行了总结,指出阻碍水流模拟发展的主要问题,提出克服这些瓶颈问题的方法是将智能科学与水利科学交叉融合,实现水流的智能模拟。据此,介绍了水流智能模型理论,结合遗传算法、模糊逻辑、元胞自动机、混沌分析理论、人工神经网络、专家系统、数据挖掘等智能理论和技术,对水流智能模拟的实现途径作了探讨,并指出建造一个优秀的水流模拟智能系统的关键是联合运用各种智能方法,认为智能化是当前水流模拟发展的新方向,水流智能模型将是水利科学的一种新的研究途径,并将在研究水流问题上具有广阔的应用前景。     

水流冲击管道内滞留气团的刚性数学模型

通过数学分析证明,在不计局部水头损失时,目前常用的几种简化刚性数学模型的最大气压计算结果相等,并与管道内初始充水段长度无关。但算例表明,对于初始充水段较短或滞留气团体积很小情况,这些简化模型的计算误差将达到不容忽视的程度,甚至导出错误结论。笔者导出的完整刚性数学模型,弥补了简化模型的不足,同时指出了刚性模型的理论缺陷和适用条件。     

鄂尔多斯盆地中生代晚期以来大地热流的变化及其对生态环境格局和演变的影响

鄂尔多斯盆地的西北部、东北部和南部三个区域现今大地热流平均值分别为56．3、67．3和65．3mW／m^2，对应的生态环境格局也有明显的差异。研究表明，大地热流每增加4～5mW／m^2可使年均地表温度升高约l℃，使最低月均地表温度升高2。C以上。鄂尔多斯盆地东北部的平均大地热流比西北部高出11mW／m^2，东北部年均地表温度可能比西北部高出2～3℃，其最低月均地表温度可能比西北部高出4～6℃。西北部的大地热流平均值已经低于维持地表生态系统延续所需大地热流的临界值(57mW／m^2)，其自然生态系统整体上已经处于脆弱境地；东北部和南部的大地热流均大于57mW／m^2，自然生态系统均尚较稳健。东北部的沙漠化可能是风沙侵入的结果，其生态应该是可以恢复的。整个西北部作为一个整体看，72万年以前大地热流就已衰减到临界值以下，区域生态系统渐趋脆弱，开始整体上向荒漠化演变。     

大渡河次级支流斯合沟泥石流特征研究

泥石流作为地质环境较差、的山区的主要自然灾害之一，对它的研究尤其是泥石流规律方面的研究已取得了较大的成绩。但是对于泥石流的研究思路却有待进一步发展和完善，这在很大程度上将对山区的工程建设有很重要的指导意义。论文从工程地质研究思路的角度出发，对位于大渡河支流官料河上某水电站下闸址区的斯合沟泥石流进行了研究。文中采用工程地质分析的方法对大渡河次级支流斯台沟泥石流的形成环境(地层岩性条件、构造条件、地貌条件、气象条件、植被发育及人类活动)、基本特征(泥石流沟的基本特征、泥石流的堆积特征)进行了系统的研究，提出了该泥石流的形成演化过程及其机制模型(初期是堰塞式沟谷型泥石流，后期逐渐转向汇聚式沟谷型泥石流)。并在此基础上对泥石流沟沿岸的岸坡稳定性(可能泥石流的物源)等进行了评价分析。将定性分析和定量分析相结合，对泥石流的活动趋势以及可能泥石流的体积(未来泥石流形成将主要是在面蚀和沟蚀作用下的坡面泥石流。泥石流规模较小，且由于沟谷中下游坡降的进一步减缓，形成的泥石流物质一般将沿途停积．实际进入官料河内的体积很小)做出了较为科学的评价预测。经过这样的系统分析对工程建设中的泥石流防治有着积极的指导意义。     

碎屑流沿坡面运动的初步分析

本文分析了碎屑流沿坡面下滑过程中的运动特性,重点考察了床面摩擦系数、土体内摩擦角和坡角对碎屑流堆积形态的影响.     

Numerical simulations for coupled rock deformation and gas leak flow in parallel coal seams

Based on the new viewpoint of interaction mechanics for solid and gas, gas leakage in parallel deformable coal seams can be understood. That is, under the action of varied geophysical fields, the methane gas flow in a double deformable coal seam can be essentially considered to be compressible with time-dependent and mixed permeation and diffusion through a pore-cleat deformable, heterogeneous and anisotropic medium. From this new viewpoint, coupled mathematical models for coal seam deformation and gas leak flow in parallel coal seams were formulated and the numerical simulations for slow gas emission from the parallel coal seams are presented. It is found that coupled models might be close to reality. Meanwhile, a coupled model for solid deformation and gas leak flow can be applied to the problems of gas leak flow including mining engineering, gas drainage engineering and mining safety engineering in particular the prediction of the safe range using protective layer mining where coal and gas outbursts can efficiently be prevented. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hydro-thermal performance of multilayer capillary barriers in arid lands

In this study, a capillary barrier system was designed and tested for an arid land environment. To simulate arid land conditions of high temperature and sub-irrigation systems, the barrier was subjected to thermal and hydraulic gradients in opposite directions; to test the barrier system under these severe conditions, an experimental apparatus was designed and fabricated. The multilayer capillary barrier consisted of three layers made of silica sand, a mixture of sand and bentonite in equal portions, and a mixture of clay (25%) and aggregate (75%). Several one dimensional coupled heat and moisture tests were performed. Temperature variations along the thickness of the barrier were recorded as a function of time, and at the end of each test, the barrier was sliced into small sections, for the determination of volumetric water content as a function of distance from the heat source. The experimental results were discussed in view of the barrier's intended purpose of its ability to store moisture for long time durations. Coupled heat and moisture flow equations were developed and solved numerically via a finite difference method. Diffusivity parameters were calculated by using experimental results, a numerical model, and Powell's conjugate directions method of nonlinear optimization. The model was calibrated and the results were discussed. Good agreement between calculated and experimental results was obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Beds comprising debrite sandwiched within co-genetic turbidite: origin and widespread occurrence in distal depositional environments

Co‐genetic debrite–turbidite beds occur in a variety of modern and ancient turbidite systems. Their basic character is distinctive. An ungraded muddy sandstone interval is encased within mud‐poor graded sandstone, siltstone and mudstone. The muddy sandstone interval preserves evidence of en masse deposition and is thus termed a debrite. The mud‐poor sandstone, siltstone and mudstone show features indicating progressive layer‐by‐layer deposition and are thus called a turbidite. Palaeocurrent indicators, ubiquitous stratigraphic association and the position of hemipelagic intervals demonstrate that debrite and enclosing turbidite originate in the same event. Detailed field observations are presented for co‐genetic debrite–turbidite beds in three widespread sequences of variable age: the Miocene Marnoso Arenacea Formation in the Italian Apennines; the Silurian Aberystwyth Grits in Wales; and Quaternary deposits of the Agadir Basin, offshore Morocco. Deposition of these sequences occurred in similar unchannellized basin‐plain settings. Co‐genetic debrite–turbidite beds were deposited from longitudinally segregated flow events, comprising both debris flow and forerunning turbidity current. It is most likely that the debris flow was generated by relatively shallow (few tens of centimetres) erosion of mud‐rich sea‐floor sediment. Changes in the settling behaviour of sand grains from a muddy fluid as flows decelerated may also have contributed to debrite deposition. The association with distal settings results from the ubiquitous presence of muddy deposits in such locations, which may be eroded and disaggregated to form a cohesive debris flow. Debrite intervals may be extensive (> 26 × 10 km in the Marnoso Arenacea Formation) and are not restricted to basin margins. Such long debris flow run‐out on low‐gradient sea floor (< 0·1°) may simply be due to low yield strength (? 50 Pa) of the debris–water mixture. This study emphasizes that multiple flow types, and transformations between flow types, can occur within the distal parts of submarine flow events.     

Nuclear Waste Disposal Simulations: Couplex Test Cases

We give some results obtained for the Couplex test cases proposed by the ANDRA. In this paper our aim is twofold. Firstly, to compute the release of nuclides out of the repository by concentrating on the 3D near field (Couplex 2). The simulation of the transport phenomena takes into account the dissolution of the glass containers and congruent emissions of the radio-nuclides including filiation chains and some simplified chemistry. Secondly, it is to use the near field computations in order to simulate the nuclide migrations in a 2D far field (Couplex 3). Coupling in between the two simulations takes into consideration the periodicity of the disposal modules and the geometry of the repository described in Couplex 1. The mixed finite element and discontinuous Galerkin methods are used to solve the convection–diffusion equations. In order to handle the nonlinear precipitation/dissolution term, we developed a new iterative technique that combines Picard and Newton–Raphson methods.