Étude expérimentale des transformations de phase dans un gradient thermique : application au granite de Soultz-sous-Forêts,France

The circulation of an injected fluid in the deep granite of the Soultz-sous-Forêts HDR (‘Hot Dry Rock’) site causes important textural and mineralogical modifications. In order to determine the potential crystallization sequences along the fluid pathway, several experiments under thermal gradient were conducted at 600 bar (between 300 and 200 °C). After 40 days, the observed sequences of the newly formed products along the thermal gradient are always as follows, from high to low temperatures: quartz, feldspars, and finally interstratified clays, this implying a significant mobility of aluminium in the solution. To cite this article: A. Baldeyrou et al., C. R. Geoscience 335 (2003).     

Barrier jets around the Southern Alps of New Zealand and their potential to enhance alpine rainfall

We use new data from the SALPEX'96 campaign to examine the evolution of orographically modified flow over and around New Zealand's Southern Alps. We consider prefrontal situations for which the larger-scale synoptic pattern generates an incoming northwesterly flow perpendicular to the mountain axis, calculate the nondimensional parameters which control the wind flow and determine how long it takes orographic modifications to become established. We place flows over the New Zealand Alps in a Rossby number/Blocking number parameter space and compare them with flows over other mountain ranges on the globe. Using model and aircraft data, we show the region of modified flow extends over 100 km upstream of the Southern Alps.We show 2D model simulations represent many aspects of the flow modification satisfactorily, although they tend to overdevelop the final state of the Barrier Jet flow. In 3D, using real data to force the boundaries, the migratory nature of the weather systems in the area would generally limit the time available for a modified steady state to develop. In addition, in situations where there is significant lateral variation of initial fields, the 2D results may only be applicable for a few hours.From the point of view of potential to influence alpine rainfall processes, for the case studied, the gradual uplift associated with the modified flow between 1 and 2 km above sea level extended far enough upstream in saturated air to enable cloud drops to grow to drizzle drops before reaching the much more substantial updrafts at the foot of the Alps. This allows vigorous prefrontal precipitation to occur over the foothills and mountains due largely to warm rain processes.     

钢混凝土组合梁低周反复荷载试验研究

本文基于钢－混凝土组合梁的低周反复荷载试验，对其破坏形态、滞回曲线、抗震延性、耗能能力、刚度退化、变形恢复能力等抗震性能进行了较为深入的研究，研究结果表明：钢－混凝土组合梁具有良好的抗震性能。     

深层搅拌桩复合地基沉降计算理论研究

为了寻找深层搅拌桩复合地基沉降计算的简便方法，根据已有的研究成果，进行了桩与桩周土间摩擦力分布规律的假设和简化，运用单位元法推导了深层搅拌桩复合地基沉降计算公式和设计用曲线，同时采用轴对称有限元法，对一实际工程的实测成果进行了分析。计算结果表明：文中理论计算的中级荷载下的沉降量值介于分层总和法与有限元法计算值之间，但文中方法比有限元计算法简单，比分层总和法更合理。     

粉喷桩复合地基的数值计算分析

结合粉喷桩复合地基的特点，提出采用过渡层模拟桩接触面的思路，进行了轴对称Biot固结有限元计算分析。与实测资料对比表明，可较好地揭示粉喷桩复合地基的荷载传递规律和沉降变形特性。通过对加固区和下卧层的应力计算分析，揭示了粉喷桩复合地基的附加应力场的分布特性，说明所采用的计算方法是合理可行的。     

赣北中元古界双桥山群地层划分的综合地层学运用

赣北前震旦系浅变质岩系一直是华南前震旦系地质研究的一个前缘阵地，多年来，在构造古地理研究方面有巨大进展。而在地层划分与对比上则相对不足。双桥山群是一大套变形强烈，岩性单调，缺乏标志层的特殊岩类。对这套特殊岩类需抓住内部的原始的沉积构造组合特征的差异。才能进行有效划分有对比。采用综合地层学方法。可以丰富岩石地层单位的研究内容，为划分提供更多的天然标志。     

小兴安岭东部9.0 ka B.P.以来沼泽发育与古环境演变研究

对迄今为止所发现的小兴安岭东部全新世最早发育的沼泽剖面进行14 C测年、孢粉分析、粘土矿物分析、泥炭植物残体鉴定 ,根据获得的信息 ,综合分析 ,相互印证 ,研究了 9.0kaB .P .以来沼泽发育、植被演替、气候变化与古地理环境演变过程。结果表明 ,本区植被演替经历五个阶段 ,即针叶林 (90 0 0aB .P .～ 830 0aB .P .)→针阔混交林 (830 0aB .P .～ 6 80 0aB .P .)→以栎、榆、胡桃为主阔叶林 (6 80 0aB .P .～ 30 5 0aB .P .)→以桦为主阔叶林 (30 5 0aB .P .～ 2 35 0aB .P .)→以松为主的针阔混交林 (2 35 0aB .P .～ 0aB .P .)。与之相对应 ,气候变化序列为 :寒冷较湿→温和略湿→温暖湿润→温凉较湿→冷凉湿润 ;沼泽发育也相应地可划分为五个时期 :沼泽孕育期 ,富营养沼泽萌发期 ,富营养沼泽旺盛发育期和中营养沼泽孕育期 ,沼泽进一步扩大发育期和中营养沼泽形成期 ,沼泽继续扩大发育期和贫营养沼泽形成期。沼泽最早开始发育始于年代为 70 95± 90aB .P .。汤洪岭 12支线沼泽剖面可作为该区全新统的标准剖面     

CFG桩复合地基边桩效应分析

CFG桩复合地基是软土地基处理中的一种较为有效的方法,近年来得到广泛的应用。通过有限元分析程序对CFG桩复合地基边桩效应进行分析,讨论边桩对CFG桩复合地基沉降、土体应力和承载力的影响。分析表明由于边桩的存在,限制了桩间土体的侧向挤出,减小了土体的竖向位移。同时,边桩增大了附加应力影响范围,能够在一定程度上提高复合地基的承载力,并促进了桩间土承载潜力的发挥。     

大直径、高置换率振冲碎石桩复合地基桩土应力特征试验分析

结合一次试桩案例,探讨分析了大直径、高置换率振冲碎石桩处理东部沿海地区填海地基的桩土应力分布特征和一般规律,并提出了一些新的理论和见解。     

滇东黔西上二叠统含煤岩系泥岩粘土矿物组成及环境意义*

滇东黔西上二叠统含煤岩系形成于陆相到海陆过渡相环境中,其泥岩的粘土矿物组成可以反映这种环境背景。该区泥岩粘土矿物类型以高岭石和伊利石/蒙皂石间层矿物为主,伊利石次之,局部层段见较少绿泥石及蒙皂石。垂向上,高岭石在富源后所矿区、盘县盘关矿区剖面中下部（即宣威组中、下段和龙潭组）含量偏高;伊利石在织金矿区剖面上部（长兴组）和下部（龙潭组下段）含量明显偏高,而在剖面中部（龙潭组上段）偏低;伊利石/蒙皂石间层矿物在后所矿区、盘关矿区、纳雍矿区占绝对优势,而在织金矿区仅在剖面中部含量较高,并与伊利石呈明显的负相关关系;蒙皂石含量很少,仅出现于盘关矿区和织金矿区剖面的上部和下部。粘土矿物的上述分布特征可大致反映出龙潭早期为海侵期,龙潭晚期为海退期,长兴期为新的更大的海侵期。平面上,从陆到海,即从滇东的冲积平原河流体系,向东经盘关向斜的上三角洲平原、纳雍的过渡带三角洲平原,到织金的下三角洲平原及潮汐平原,高岭石含量急剧减少,伊利石含量逐渐增加。最为明显的是从滇东河流体系到黔西三角洲—潮坪体系之间高岭石含量骤然减少。