论桩基施工中流砂现象处理

地下水流动对土体产生渗透力；当渗透力大于土体的抗剪强度，土体破坏，也就是当施工造成地下水水力坡度超过砂层的临界水力坡度即产生流砂现象．运用水文地质工程地质学方面的原理其处理方法有两类：—是莫尔一库仑法：即c法和φ法；二是临界水力坡度法(Ic法)．     

Flooding of Sinking Creek,Garretts Spring karst drainage basin,Jessamine and Woodford counties,Kentucky, USA

Tashamingo Subdivision in Sinking Creek karst valley, a tributary of the Garretts Spring drainage basin in Jessamine and Woodford counties, Kentucky, was flooded in February 1989. To determine the cause of flooding, the groundwater basin boundary was mapped, discharge data were measured to determine intake capacity of swallets, and hydrologic modeling of the basin was conducted. Swallet capacity was determined to be limited by the hydraulic parameters of the conduit, rather than by obstruction by trash. Flooding from a precipitation event is more likely, and will be higher, when antecedent soil moisture conditions in the watershed are near saturation. Hydrologic modeling shows that suburban development of 20 percent of the southeast basin will cause a small increase in flood stage at Tashamingo Subdivision.     

Comparison of the results of quantitative and non-quantitative tracer tests for determination of Karst conduit networks: An example from the Traligill Basin,Scotland

The relative advantages of fluorescent dyes and Lycopodium spores as tracers are discussed. The major advantage of fluorescent dyes is that they may be detected quantitatively. Thus, in combination with discharge measurements, a dye mass balance can be prepared for tracer tests in karst conduits, which permits elucidation of the underground network. The advantages of this procedure are illustrated by comparison of the networks derived from non-quantitative (Lycopodium and dye) and quantitative (fluorescent dye) tracer methods in the Traligill Basin, Scotland. These tests also suggest that Lycopodium does not give a true indication of travel time, due to sedimentation underground. This could also cause contamination problems in later tests. For non-quantitative tracer tests, sensitive methods are necessary if incorrect inferences on conduit networks are to be avoided. In general, however, quantitative tests give much less ambiguous results, and are therefore to be preferred.     

A new assessment model for evacuation vulnerability in urban areas

In the high-speed urbanization process of China, the urban population has been increasing significantly, leading to a high-density aggregation of population. However, the sharp increase in population density has not produced commensurate improvements in the road networks. On the contrary, the population increase induced a serious evacuation vulnerability, which cities experience during various hazards and catastrophic events. Therefore, research on evacuation vulnerability is important to urban planning. To assess the evacuation vulnerability, the optimal and worst scenarios should be considered because all possible evacuation plans occur between these extremes. However, most previous evacuation vulnerability studies are based on the worst-case scenario, only providing an upper bound of a potential evacuation assessment. To provide a more comprehensive theoretical basis for decision-makers to understand the consequences caused by all possible evacuations, this paper proposes an optimal evacuation vulnerability assessment model that provides the lower bound on potential evacuation difficulties. The model is solved by a stepwise spreading algorithm based on Graph Theory. Subsequently, to evaluate the effectiveness of the model, the study adopts the model to assess the evacuation capability of different road network topologies. A comparison with previous research was performed. The model was demonstrated in an application to the South Luogu Alley of Beijing, China. The significance of this paper is that the combination of our model with previous research may provide a more complete theoretical basis for an evacuation vulnerability assessment.     

极限平衡理论下边坡强度参数反演及加固稳定性分析

参数反演是获得较为可靠的边坡强度参数的一种有效手段。本文在对边坡临界滑动面进行判别的情况下,以瑞典法为基础,通过建立强度参数之间及其与临界滑动面一一对应的关系推导得边坡强度参数反演的显式计算公式。然后,将反演结果用于锚索加固条件下的边坡稳定性研究。经工程算例分析验证了本文方法的可行性和实用性,并得到如下结论:(1)预应力锚索能对边坡形成有效的加固作用,且锚索在坡面上的位置越靠近滑动面的滑出点时其对边坡的稳定性越有利; (2)锚索的预应力越大则计算得到的安全系数越大,而锚索水平倾角的增大对计算得到的安全系数影响微小。     

Changing grading of soil: effect on critical states

Examples of situations are presented where the grading of a soil changes during its lifetime either by crushing of particles leading to an increase of fine material or by slow transport of fine particles with seepage leading to a decrease of fine material. Such grading changes influence the basic constitutive properties of the soil, in particular properties such as critical states which are dependent on the available range of densities of packing. Discrete element modelling is used to show the dependence of critical state conditions on grading and the way in which the particle assembly seeks out new critical state conditions as the grading changes.     

论青藏高原隆起作用于大气的临界高度

在以前工作的基础上，从大气动力学、热力学及气候学的角度，进一步论证了在青茂高原隆起过程中存在一个临界高度ｈｃ（－１．５－２ｋｍ）。当高原隆起突破这一临界高度时才开始对大气产生强烈的作用，从而造成大气环流、大气热力结构、亚洲区域以及全球气候等一系列巨大转变。     

Jadeitites, albitites and related rocks from the Motagua Fault Zone, Guatemala

Jadeitites from Guatemala are found as weathered blocks in tectonized serpentinite in a 15-km zone north of the Motagua Fault Zone. Rock types found with jadeitite include albitites, albite-mica rocks, omphacite/taramitic amphibole-bearing metabasites, chlorite-actinolite schists, talc-carbonate rocks and antigorite schists. In addition to the predominant jadeitic (Jd₉₃_₁₀₀) pyroxene, common phases in jadeitite include micas (paragonite and/or phengite ± rarer phlogopite), omphacite, albite, titanite /Pm zircon, apatite and graphite. Conditions of jadeitite formation are 100-400d? C, 5-11 kbar with 0.0 > log₁₀a_sio2≥= 0.7. Fluid inclusions, coarse textures, vein structures, and rhythmic zoning of pyroxene indicate an aqueuos fluid was involved. Jadeitites are either (1) metasomatic modifications of former felsic-to-pelitic inclusions that have undergone silica depletion plus efficient soda exchange and enrichment, or (2) solution precipitations derived from such a source. The close spatial relationship of faults and shear zones, serpentinites, and jadeitites suggests jadeitites form in a relatively high-P/T setting with substantial flow of sodic fluid in a tectonized zone. Most Guatemalan jadeitites are extensively altered to analcime, albite, taramitic amphibole, (clino)zoisite ± nepheline and preiswerkite. This alteration reflects depressurization /Pm heating to below the jadeite + fluid = analcime reaction at high a_Na. With progressive alteration, analcime and nepheline are replaced by albite; the increase in silica content may result from fluid flowing up a tectonized zone reaching saturation with an albite assemblage. Albitite phases, albite, actinolite, zoisite, /Pm chlorite, phengite, K-feldspar and quartz, record conditions of c. 3-8 kbar at T < 400d? C, indicating a clockwise P-T trajectory of the blocks. Barium aluminosilicates—banalsite, celsian, cymrite and hyalophane—are common minor late-stage phases in jadeitites and albite-rich rocks. Barian phengite is common in albite-mica rocks.     

岩溶区层状缓倾角岩质边坡变形破坏机制研究

在贵州岩溶区某大型工程台址工程地质环境条件研究基础上,采用地质历史过程机制分析法和数值模拟方法,对岩溶区层状缓倾角岩质边坡变形破坏机制作系统研究,总结出了4种变形破坏机制,即高陡的层状缓倾内边坡(A类坡)主要发生倾倒-崩落或拉裂-崩落破坏,低矮的层状缓倾内边坡(C类坡)则以小规模垮塌为主;缓倾外顺层边坡(B类坡)以滑移-拉裂型顺层滑坡或块状滑坡为主,而复合型边坡(D类坡)多以滑移-拉裂和弯曲-拉裂组合形式发生破坏.     

Metamorphic evolution of oceanic gabbros: recrystallization from subsolidus to hydrothermal conditions in the MARK area (ODP Leg 153)

The 117.38 m of gabbroic core drilled during the Ocean Drilling Program (ODP) Leg 153 at Sites 921 to 924 in the Mid-Atlantic Ridge (MAR) between 23 °N and the Kane Fracture Zone, exhibits a remarkable primary compositional heterogeneity, such as magmatic layering, intrusive contacts and late magmatic veining, which express a succession of magmatic events. Textural indicators suggest that the cooling of the crystal mush occurred in a dynamic environment, with infiltration of progressively evolved liquids. Magmatic features include random shape fabric and magmatic lamination; the subsequent deformational overprint occurred in subsolidus conditions. The ductile deformation, generally concentrated in discrete domains of the gabbro, is associated with continuous re-equilibration of the metamorphic assemblages of (1) olivine + clinopyroxene + orthopyroxene + plagioclase + ilmenite + Ti-magnetite, (2) olivine + clinopyroxene + plagioclase + ilmenite + Ti-magnetite + red hornblende. At lower temperatures brittle deformation prevails and subsequent fractures control the development of metamorphic assemblages: (3) clinopyroxene + plagioclase + red brown hornblende + Ti-magnetite + magnetite (?) + ilmenite, (4) plagioclase + brown hornblende + Ti-magnetite + magnetite + hematite + titanite ± Ti-oxide, (5) plagioclase + green hornblende + magnetite + titanite, (6) plagioclase + actinolite + chlorite + titanite + magnetite, (7) albite + actinolite + chlorite + prehnite ± epidote ± titanite and (8) albite + prehnite + chlorite ± smectite. Assemblages 1 to 8 express increasing water/rock ratios and decreasing degrees of recrystallization.

During the ductile phase, red hornblende is stable and its abundance increases with deformation intensity, possibly as an effect of the introduction of hydrous fluids. During the brittle phase, water diffusion controls the development of the fracture-filling mineral assemblages and re-equilibration of the adjacent rock; temperatures decrease further, as demonstrated by mineral zoning and incompletely re-equilibrated assemblages. The lowest temperatures correspond to the development of hydrothermal assemblages.

Compared with oceanic gabbros from fast-spreading transform environments, high-temperature ductile phases (granulite and amphibolite) are well developed, whereas brittle phases are widespread, as microcracks, prevalent on fracturing associated with discrete veins.