桩底注浆钻孔灌注桩承载力的研究

通过天津地区几例钻孔灌注桩桩底注浆的静载荷试桩结果 ,分析天津地区钻孔灌注桩桩底注浆单桩竖向极限承载力标准值的估算方法     

垫层对CFG桩复合地基影响的分析

对CFG桩复合地基垫层进行分析 ,探讨了垫层厚度和模量对桩土应力比、桩侧摩阻力、沉降变形、承载力的影响 ,并得出一些规律     

An invariance in the carbazoles of petroleum

A remarkable invariance in the ratio of 1,3-dimethylcarbazole （DMC） to 1,6-DMC was discovered in crude oils from the Pearl River Mouth Basin, South China Sea. The remarkably invariant ratio is kept at a constant of about unity regardless of their concentrations, sources or maturities for the sampies. In combination with the molecular structures of 1,3- and 1,6-DMCs, the invariance might indicate that the nitrogen compounds share a common precursor with a skeleton of 1-methylcarbazole and are formed through methylation at C3 and C6 with an essentially identical rate.     

Détermination expérimentale des paramètres équivalents d'un milieu poreux hétérogène en écoulements uniforme ou radial

Tracer tests are carried out in a heterogeneous porous medium that has a 3D correlated random distribution of the permeabilities. The fitting of numerical models provides the values of equivalent permeability and macrodispersivity characterizing a 2D homogeneous horizontal medium. Different flow configurations are studied: uniform, radial and pump and treat (doublet). The fitted parameter sets are independent of the flow type, except for the doublet. They are greater than the values predicted by stochastic theories, due to the small number of correlation lengths explored by the tracer and the limited extension of the experimental set-up. To cite this article: C. Danquigny, P. Ackerer, C. R. Geoscience 337 (2005).     

用叠加谱比法研究新疆地区Lg尾波Q值的区域性变化

运用叠加谱比法,对分布于新疆地区的5个台站所记录的51个地震数据进行分析,得出与各射线路径相对应的Lg尾波Q0(Lg尾波在1Hz处的Q)值。结果表明:Q0值呈现出明显的区域性变化特点,与构造活动关系紧密。在较为稳定的塔里木地台,Q0呈现出高值,在350～450之间。在南部构造活动较为激烈的昆仑褶皱系,Q0呈现出较低的值,约为200～250。在构造活动最为激烈的帕米尔地区,Q0值在170～200之间。在北部的天山褶皱系,Q0值约为220～270。准葛尔褶皱系比天山褶皱系的Q0值略高,约为260～290。     

楚科奇海表层沉积物的生源组分及其对碳埋藏的指示意义

工业革命以来大气中CO₂浓度由280 ppm剧增至375 ppm,是导致全球气候变暖的主要原因[1]。海洋作为大气CO₂的“汇”之一,每年可吸收人类释放CO₂气体总量的30%,对全球碳循环的收支平衡有重要作用[2]。两极地区是CO₂的主要汇区,也是全球变化的重要反馈窗口。因此,了解碳在北冰洋的生物地球化学循环过程是十分必要的[3-4]。海洋中的生源沉积物主要来自于海洋上层浮游生物碎屑的沉降,主要由蛋白石(以生物硅代替,BSi)、碳酸钙(CaCO₃)和有机质(通常用有机碳替代,TOC)组成[5]。     

元素分析仪-同位素比值质谱测量碳氮同位素比值最佳反应温度和进样量的确定

沉积有机质的碳氮稳定同位素值是进行古气候、古环境及生态系统研究不可或缺的主要研究手段,目前碳氮同位素主要利用元素分析仪-同位素比值质谱(EA-IRMS)系统来测定。EA-IRMS测定过程中的反应温度及样品进样量直接影响反应物在测试中的燃烧程度,从而影响测试数据的精度。本文利用EA-IRMS技术,以标准样品为参考,在不同转化温度下测试碳氮同位素值,研究保证测试精度的最佳反应温度条件;同时,通过分析不同含氮量样品的检测限,明确了样品含氮量与最低检测限之间的关系,确定了精确测定氮同位素值的最低进样量。结果表明:反应温度对测试精度有显著影响,在碳同位素测定时,将反应温度设定为900℃或以上时测试精度均能达到±0.2‰;氮同位素测定时,反应温度须设定为950℃时测试精度才能达到±0.3‰。实验得出样品含氮量与检测限之间的线性相关性为R2=0.873,开展氮同位素测定时可根据此关系来判断和控制进样量。     

A Comparative Study of Landsat‐7 and Landsat‐8 Data Using Image Processing Methods for Hydrothermal Alteration Mapping

Comparing spaceborne satellite images of Landsat‐8 Operational Land Imager (OLI) and Landsat‐7 Enhanced Thematic Mapper plus (ETM+) was undertaken to investigate the relative accuracy of mapping hydrothermal alteration minerals. The study investigated the northern part of Rabor, which contains copper mineralization occurrences, and is located in the Kerman Cenozoic magmatic assemblage (KCMA), Iran. Image processing methods of band ratio, principal component analysis (PCA), and spectral angle mapper (SAM) were used to map the distribution of hydrothermally altered rocks associated with the porphyry copper mineralization. The band ratio combination of both sensors for mapping altered areas showed similar outcomes. PCA exposed variations in the spatial distribution of hydroxyl‐bearing minerals. The representation of hydrothermal areas using OLI data was more satisfactory than when using ETM+ data. SAM analysis found similar results for mapping hydroxyl‐bearing zones. Verification of the results came through ground investigation and laboratory studies. Rock samples (n = 56) were collected to validate results using thin sections, X‐ray diffraction (XRD) and spectral analyses. Field observations and laboratory analysis revealed that phyllic and propylitic alterations dominate the alteration zones in the study area. Argillic and iron oxides/hydroxides alterations were observed to a lesser degree. The results indicate that alteration maps prepared by OLI data using PCA for visual interpretation are more suitable than those of ETM+ due to a higher radiometric resolution and lower interference between vegetation and altered areas. As the spectral bandwidth of ETM+ band 7 covers absorption feature of propylitic alteration, better mapping of propylitic alterations is achieved using ETM+ data.     

钙钠离子对蒙脱石吸水特性的影响

本文测定蒙脱石胶体和膨润土吸水率及吸水比,研究钙钠离子对其吸水特性的影响。研究结果表明,钙质蒙脱石、膨润土在吸水24h内的吸水率和吸水速度均高于钠质的;而24h后则前者低于后者。钙质蒙脱石和膨润上的吸水比>50％,而钠质的<50％。     

基于季节冻土微观结构特征的神经网络冻胀率仿真预测

为了寻求基于宏观-微观物理参数间接得到季节冻土冻胀率的途径, 根据现有技术手段容易测试到土的性质参数, 利用BP神经网络法对季节冻土冻胀率进行预测. 选取微观孔隙参数及结构单元体参数各4个、 外部条件参数3个共11个参数, 建立季节冻土冻胀率神经网络预测模型. 结果表明: 在33个检验样本中, 误差最大为0.19, 最小为0.00, 有4个样本的误差在0.1~0.19之间, 其他样本误差都在0.05以下, 占总样本数的88%, 说明模型能反映冻胀变化的基本趋势. 因此, 文中建立的基于11个宏观微观物理参数的BP神经网络冻胀率预测模型是可行的.