Influence of groundnut shell ash on strength and durability properties of clay

Groundnut shell ash, cement and their combinations are used as soil stabilizers in various percentages to improve the strength of locally available highly compressible clay soil. The effect of stabilizer in improving the strength of the soil is evaluated through change in consistency limits, compaction characteristics, undrained cohesion and modulus of elasticity. The durability characteristics of stabilised soil were studied based on the improvement of undrained shear strength for various days of curing by increasing the percentage of cement. Stabilised soil showed satisfactory improvement in strength and consistent durability characters. Groundnut shell ash and cement increased the optimum moisture content. There was a slight decrease in the dry density and modulus of elasticity of soil. These can be used as a viable economic alternative in construction of roads and for stabilising soil acting as bearing medium. The use of groundnut shell ash, an agricultural waste, helps in waste management and promotes sustainable development of local construction industry.     

影响长江口区热带气旋的特征分析

根据 1979—2002年大戢山和引水船的观测资料,结合西北太平洋热带气旋年鉴资料,统计和分析了热带气旋对长江口区的影响规律,统计结果显示,在近 24 a中,热带气旋年均有 2.0个,通常出现在6— 10月期间,以 月份最多,发生频数为 8 45.8 %;严重影响长江口区的热带气旋年均只有 0.3 个,有60 %集中在 月份,都属海上转向型;影响长江口的热带气旋源区 8 90 % 位于菲律宾和琉球群岛以东洋面,且有超过一半生成于10°N ~ 20°N;影响长江口区热带气旋次数存在 4 ~ 6 a 的小周期波动和 10 a 左右的周期变化,并且在厄尔尼诺年的影响次数较反厄尔尼诺年少。     

敲击-回波法中传感器影响的小波分析

在基桩及结构物质量的敲击-回波法检测过程中,由传感器采集的信号里除反映了被测点的速度响应外,还总是含有传感器固有特性引起的成份。首先利用数值模拟软件FLAC3D对不含传感器的桩顶速度响应进行数值模拟,再与传感器特性进行合成,得到含有传感器特性的桩顶速度响应;然后利用小波分析,研究了传感器对速度响应的影响;最后,提出了一种新的抑制传感器影响的方法--小波抑制法,结果表明：小波分析能有效地抑制速度响应中传感器的影响     

The Mesozoic–Cenozoic organic facies in the Lower Tagus sub-basin (Lusitanian Basin,Portugal): Palynofacies and organic geochemistry approaches

Studies of the Mesozoic and Cenozoic sequence crossed by the Barreiro-4 borehole provide an improved understanding of the organic matter deposited in the Lower Tagus sub-basin (Lusitanian Basin, Portugal) and the implications for the potential source rock and depositional environment. This study focused on 43 samples (Middle Jurassic to Neogene) that were subjected to palynofacies and organic geochemistry analyses (Total Organic Carbon, Rock-Eval pyrolysis and molecular biomarker analysis). The palynofacies data indicate that the sequence contains mainly phytoclasts (non-opaque phytoclasts). However, the Middle Jurassic samples are dominated by Amorphous Organic Matter (AOM). Continental and/or marine palynomorphs are present in all the samples. The Cretaceous samples are characterized by small amounts of kerogen that have high contents of solid bitumen. The Total Organic Carbon (TOC) content is generally less than 1 wt.%. The Rock-Eval S1 and S2 parameters vary from 0.01 to 3.50 mgHC/g rock and 0.15 to 34.03 mgHC/g rock, respectively, with the highest values corresponding to the Cretaceous samples. The hydrogen index (HI) and oxygen index (OI) values range from 35 to 552 mgHC/g TOC and 4 to 180 mgHC/g TOC, respectively. The T_max values range from 416 to 437 °C. The biomarker analysis showed that n-alkanes with 15–30 carbon atoms are present and usually have a unimodal distribution with a predominance of low to medium molecular weight compounds. The CPI values range between 0.63 and 3.65, and the pristane/phytane ratios vary between 0.48 and 1.64, indicating alternation of oxic–anoxic conditions along the sequence. The distribution of terpanes shows small amounts of tricyclic and tetracyclic terpanes in most of the samples (except for some Cretaceous samples) and a predominance of pentacyclic terpanes. The amount of 17α (H),22,29,30-trisnorhopane (Tm) usually exceeds the amount of 18α (H),22,29,30-trinorneohopane (Ts). The 20S/(20S + 20R) and αββ/(ααα + αββ) ratios of the C29 steranes generally have values below the range of equilibrium, indicating an immature stage of the OM.     

南海西北次海扩张时代和洋壳性质:沉积地层及重磁依据

利用沉积地层被动超覆和基底重磁异常特征对南海西北次海形成时代和洋壳性质进行了探讨。推断南海西北次海初始扩张时间为早渐新世,结束扩张时间为晚渐新世早期。地层变形、被动超覆特征、洋壳基底形态及对称性特点反映出两期洋壳扩张事件。第一期发生在早渐新世。由于洋壳扩张,上始新统被拉断,在洋壳边界处上始新统突然终止现象明显。受洋壳横向扩张推挤和纵向沉降作用影响,上始新统明显变形,并向扩张中心倾覆。第二期洋壳扩张发生在晚渐新世早期。该期洋壳扩张持续时间短,扩张幅度小,下渐新统被拉开的距离有限。由于南海西北次海形成期间不同部位地壳伸展减薄程度不同,南海西北次海洋壳基底呈北东部较宽,向南西方向变窄,并逐渐尖灭的不规则三角形。根据盆地边缘上始新统向海盆中心方向的断点/线和重磁异常资料,推测西北次海南西侧洋壳边界位于海盆基底坡角处附近,洋壳较窄;而北东侧洋壳边界位于海底坡角处附近,洋壳相对较宽。另外,重磁异常表明,在洋壳基底中有陆壳残留块体存在。上述这些现象说明南海西北次海在洋壳萌芽阶段就先天夭折,停止发育。     

干酪根分子结构在低熟阶段的演化特征：基于红外光谱分析

为研究低熟气形成过程中大分子结构的变化情况,对吐哈盆地侏罗系八道湾组的煤与碳质泥岩干酪根在不同升温速率下进行了热解实验,借助于红外光谱分析,研究了不同热模拟温度下干酪根结构的特征与变化。结果表明,随热演化的进行,煤与碳质泥岩干酪根的芳香结构不断缩合,含氧官能团不断脱落,碳质泥岩干酪根中的脂肪族类有所降低。吐哈盆地低熟气主要来源于煤与碳质泥岩干酪根中的含氧官能团--羧基与甲氧基,以及碳质泥岩干酪根上的脂肪族。从干酪根结构上揭示了低熟气主要来源于Ⅲ型有机质的原因。     

贵州东部镇远金堡铅锌矿床地球化学特征研究

对贵州黔东镇远金堡铅锌矿床碳—氧、硫同位素及流体包裹体温度、盐度地球化学特征研究,方解石和白云石碳同位素在-5.7‰-6.9‰,落在典型的火成碳酸岩区域(-5‰-7‰);氧同位素在11.2‰12.2‰之间,略高于火成碳酸岩。闪锌矿硫同位素分布集中,在11.5‰14.2‰之间,结合该区域的碳同位素,暗示成矿物质来自于深部地幔或岩浆作用。流体包裹体均一温度在106 238℃之间,冰点温度在-1.8-24℃之间,对应的盐度为2.926.1 wt%NaCl eq.,判断该矿床成矿流体属中低温、中高盐度的成矿流体。从闪锌矿流体包裹体均一温度-盐度变化趋势分析,成矿温度及盐度范围变化较大,成矿流体经历了不混溶过程,可能是岩浆热液在降温减压的过程中发生不混溶现象而形成的。结合区域地质条件及矿床地质特征分析研究,认为镇远金堡铅锌矿床成矿热液来源及其可能与岩浆热液有关。     

成都金沙遗址青铜器的化学特征及矿质来源

在总结前人对商周遗址中青铜器研究的基础上,通过对成都金沙遗址出土青铜器的铅同位素和主要金属元素含量的测定,分析讨论了金沙青铜器的化学特征及可能的矿质来源。通过对测定结果的分析认为：青铜器的冶炼过程中人为进行铜铅锡含量配比的迹象并不明显,更多体现出直接利用多金属矿的结果;金沙遗址中青铜器的铅同位素值大部分异常高,表现出N（206Pb）/N（204Pb）大于20。根据区域地质资料和前人对多金属矿床的研究结果,认为金沙青铜器的铜矿石极有可能来自于距离较近的会理拉拉厂铜矿。     

黔北牛蹄塘组黑色岩系中的矿产特征及找矿远景分析

黔北牛蹄塘组为早寒武世梅树村期沉积的一套黑色岩系,其下段（习称＂黑层＂）普遍含镍、钼、钒、铀、磷等多元素矿产,钒分布普遍常赋存于＂黑层＂的简单岩性组合区,而镍、钼富集于＂黑层＂的复杂岩性组合区,磷、铀则不受＂黑层＂岩性组合的控制。本文通过对黔北＂黑层＂含矿组合、合矿性和典型矿床地质特征及岩相古地理环境的分析和总结,认为牛蹄塘组下部＂黑层＂在黔北具较大的找矿空间和找矿前景,进而指出了找矿方向和找矿远景区。     

分形理论在交通网络分布形态研究中的应用

探讨了以分形几何理论为基础的表达空间网络分布特征的几种分维数,重点描述了相似分维数的定义及其地理意义,以实例说明了相似分维数在交通网络分布特征研究中的应用,对测算结果进行了分析和评述。