矿区控制网布网方案的选择

用计算机模拟法,讨论了控制网不同观测量的平差结果,提出了选择矿区控制网方案的原则.     

印度洋岸边某电站工程的岩土工程问题初探

从海岸地带的地理地质环境入手,针对燃煤电站工程的特点,就工程建设中的几个主要岩土工程问题,分析探讨了其成因、特点和对工程建设的制约与影响程度．提出了解决这些问题的对策和建议。     

高地震区公路隧道地震动力响应分析

基于土一结构相互作用理论,对高地震区一实际重大工程的公路隧道洞口段结构进行了抗震计算,得到了衬砌结构各控制点的位移、加速度及内力响应规律。结果表明：在人工合成地震波条件下,衬砌墙脚、拱腰为抗震薄弱位置;结构的加速度波形与输入波形相似;这些结果为抗震设计提供了一些依据。     

某基坑工程土钉支护工作性状试验研究

通过对广州天河荟雅苑基坑工程土钉支护进行试验和研究,分析了土钉支护体系的工作性状,并为同类工程的设计提供了一定的依据。     

Cambrian explosion: Birth of tree of animals

Excluding the sponges the Kingdom Animalia is usually divided into three subkingdoms: Diploblasta, Protostomia and Deuterostomia. The Cambrian Explosion consists of three major episodes, two of which were in the early Early Cambrian (one represented by the small skeletal fossils “SSFs” at the base of the Cambrian and the other represented by the succeeding Chengjiang faunas “CFs”), and the other episode as their prelude took place in the “Eocambrian” (i.e. the latest Precambrian), represented by the Ediacaran faunas. This unique Big Bang of life has been recognized as giving birth to the entire morphological Tree Of Animals (or metazoans), in short the TOA. Its “seed” in the deep Precambrian, represented by some sort of protist from which the complete TOA must have grown, remains unknown paleontologically. However, the fossil evidence suggests that the three major episodes of the Cambrian Explosion are responsible for the earliest radiations of the three subkingdoms of animals respectively. While the observed Ediacaran fauna might constitute only a small part of the whole Ediacaran biota, our evidence supports that it was dominated by diploblasts (the “trunk” of the TOA) with only a few possible stem-group triploblasts. The Early Cambrian in turn in two phases explosively yielded almost all the major triploblastic crown-branches (Bilateria: the huge “crown” of the TOA), which include the other two subkingdoms: first the extremely diverse protostomes in the Meishucunian Age and then followed by a nearly entire lineage of early deuterostomes from the Chengjiang, including even its most derived member – the earliest true vertebrates. Among the four most significant milestones of morphological origins and radiations in animal history, the first one (i.e. appearance of metazoans) took place in the Ediacaran Period or earlier times, and the other three can be seen in the windows available from the Chengjiang and the Meishucunian fossil assemblages. The newly discovered extinct Phylum Vetulicolia, which has primitively segmented body with simple gill slits in its anterior division, most probably represents one of the roots of the deuterostome subkingdom. Showing a mosaic of basic features possessed in both the bilateral vetulicolians and some primitive echinoderms, the soft-bodied vetulocystids are best regarded as one of the roots of the extant pentamerous echinoderms. Standing on the “top” of the deuterostome super-branch in the early Cambrian TOA are the “the first fish” Myllokunmingia and Haikouichthys, which bear paired eyes and salient proto-vertebrae. These animals represent the real root of the remainder of the vertebrates or craniates. On the contrary, yunnanozoans, including Yunnanozoon and Haikouella, possess neither eyes nor unequivocal vertebrae, and may have nothing to do with the craniates, let alone the vertebrates. Those enigmatic creatures share a similar body-plan with vetulicolians and should be treated as a side-branch within the lower deuterostomes.     

Numerical simulation of a stratigraphic model

A multi-lithology diffusive stratigraphic model is considered, which simulates at large scales in space and time the infill of sedimentary basins governed by the interaction between tectonics displacements, eustatic variations, sediment supply, and sediment transport laws. The model accounts for the mass conservation of each sediment lithology resulting in a mixed parabolic, hyperbolic system of partial differential equations (PDEs) for the lithology concentrations and the sediment thickness. It also takes into account a limit on the rock alteration velocity modeled as a unilaterality constraint. To obtain a robust, fast, and accurate simulation, fully and semi-implicit finite volume discre tization schemes are derived for which the existence of stable solutions is proved. Then, the set of nonlinear equations is solved using a Newton algorithm adapted to the unilaterality constraint, and preconditioning strategies are defined for the solution of the linear system at each Newton iteration. They are based on an algebraic approximate decoupling of the sediment thickness and the concentration variables as well as on a proper preconditioning of each variable. These algorithms are studied and compared in terms of robustness, scalability, and efficiency on two real basin test cases.     

Use of unit response functions for management of regional multilayered aquifers: application to the North Aquitaine Tertiary system (France)

Although there are many numerical applications used in aquifer management, few methodologies seem to be sufficiently adapted to provide solutions for regional-scale problems. Their applications for multilayered aquifers are also too limited. A new groundwater management tool adapted to such large physical systems has been developed, using the unit response function (URF) approach. This tool is based on the link between a numerical groundwater flow model and a mathematical optimisation tool. Pre- and post processing are based on a geographical information system (GIS). The developed tool has been applied to a real management case—the regional Aquitaine multilayered aquifer (France). A representative hydrodynamic model was built using MODFLOW 2000 code. First tests show that the linearity condition needed for the application of URF methodology is respected despite the high complexity of the system. Two management scenarios were tested. Optimal solutions thus obtained allow for viable exploitation alternatives to be proposed, which integrate complex environmental constraints.

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Résumé Malgré un nombre important d’applications existant dans le domaine de la gestion des aquifères, peu de méthodologies semblent adaptées pour proposer des solutions à des problèmes réels de dimension régionale. Leurs application pour des systèmes multicouches sont souvent trop limitées. Un outil de gestion adapté à ces systèmes de large taille a été développé, basé sur la théorie des Fonctions de Réponses Unitaires (FRU). Cet outil est basé sur le couplage d’un modèle numérique d’écoulement et d’un code d’optimisation mathématique. Les entrées et sorties du modèle sont réalisées à l’aide d’un Système d’Information Géographique (SIG). L’outil développé est appliqué à un cas de gestion réel—le système aquifère régional multicouche aquitain (France). Un modèle hydrodynamique représentatif a été construit, basé sur le code MODFLOW 2000. Les premiers tests montrent que les conditions de linéarité nécessaires à l’application de la méthode FRU sont respectées, malgré l’importante complexité du système. Deux scénarii de gestion sont testés. Les solutions optimales ainsi obtenues permettent de proposer des solutions d’exploitation alternatives viables, intégrant des contraintes environnementales complexes.

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Resumen Aunque hay muchas aplicaciones numéricas usadas en la gestión de acuíferos, unas pocas metodologías parecen estar adaptadas suficientemente para dar las soluciones a los problemas de escala regional. También son limitadas sus aplicaciones para los acuíferos multicapa. Se ha desarrollado una nueva herramienta para el manejo del agua subterránea, adaptada a tales sistemas físicos grandes, usando el avance de la Función de Respuesta Unitaria (URF). Esta herramienta se basa en la combinación entre un modelo numérico de flujo de agua subterránea y una herramienta de optimización matemática. El pre-proceso y el post-proceso se basan en un Sistema de Información Geográfico (GIS). La herramienta desarrollada se ha aplicado a un caso real de manejo en el acuífero regional multicapa de Aquitania (Francia). Se construyó un modelo hidrodinámico representativo, que usó el código MODFLOW 2000. Las primeras pruebas muestran que la condición de linearidad, necesaria para la aplicación de la metodología URF, se respeta a pesar de la complejidad alta del sistema. Se probaron dos escenarios de manejo. Las soluciones óptimas así obtenidas permiten la proyección de alternativas viables de explotación, las cuales integran restricciones medioambientales complejas.

     

Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer,Middle East

Assessment of recharge in a structurally complex upland karst limestone aquifer situated in a semi-arid environment is difficult. Resort to surrogate indicators such as measurement of spring outflow and borehole discharge, is a common alternative, and attempts to apply conventional soil moisture deficit analysis may not adequately account for the intermittent spate conditions that arise in such environments. A modelling approach has been made using the West Bank Mountain Aquifer system in the Middle East as a trial. The model uses object oriented software which allows various objects to be switched on and off. Each of the main recharge processes identified in the West Bank is incorporated. The model allows either conventional soil moisture deficit analysis calculations or wetting threshold calculations to be made as appropriate, and accommodates both direct recharge and secondary recharge. Daily time steps enable recharge and runoff routing to be calculated for each node. Model runs have enabled a series of simulations for each of the three aquifer basins in the West Bank and for the whole of the West Bank. These provide recharge estimates comparable to those prepared by earlier workers by conventional means. The model is adaptable and has been successfully used in other environments.     

Numerical simulation of migration–accumulation of oil resources

Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value to the evaluation of oil resources and to the determination of the location and amount of oil deposits. This thesis discusses the characteristics of petroleum geology and permeation fluid mechanics. For the three-dimensional problems of Dongying hollow of Shengli Petroleum Oil Field, it puts forward a new model and a kind of modified method of upwind finite difference fractional steps implicit interactive scheme. For the famous hydraulic experiment of secondary migration–accumulation, the numerical simulation test has been done, and both the computational and experimental results are basically identical. For the actual problem of Dongying hollow, the numerical simulation test and the actual conditions are basically coincident. Thus, the well-known problem has been solved.     

Estimating hydraulic conductivity using grain-size analyses, aquifer tests, and numerical modeling in a riverside alluvial system in South Korea

Hydraulic conductivity (K) for an alluvial system in a riverbank filtration area in Changwon City, South Korea, has been studied using grain-size distribution, pumping and slug tests, and numerical modeling. The alluvial system is composed of layers: upper fine sand, medium sand, lower fine sand, and a highly conductive sand/gravel layer at the base. The geometric mean of K for the sand/gravel layer (9.89?×?10^?4 m s^?1), as determined by grain-size analyses, was 3.33 times greater than the geometric mean obtained from pumping tests (2.97?×?10^?4 m s^?1). The geometric mean of K estimates obtained from slug tests (3.08?×?10^?6 m s^?1) was one to two orders of magnitude lower than that from pumping tests and grain-size analyses. K estimates derived from a numerical model were compared to those derived from the grain-size methods, slug tests and pumping tests in order to determine the degree of deviation from the numerical model. It is considered that the K estimates determined by the slug tests resemble the uppermost part of the alluvial deposit, whereas the K estimates obtained by grain-size analyses and pumping tests are similar to those from the numerical model for the sand/gravel layer of the riverside alluvial system.