Thaw-induced slope failures and stability analyses in permafrost regions of the Qinghai-Tibet Plateau,China

The distribution of permafrost-related slope failures along the Qinghai-Tibet Highway from Wuddaoliang to Fenghuoshan correlates with ice content, slope gradient, and ground temperature. Slope failures are of two types. (1) Retrogressive thaw slumps result from icy permafrost being exposed by either man-induced excavation or fluvial-thermal erosion and undercutting of basal slopes. (2) Active-layer-detachment failures are caused by thaw of icy permafrost at the active layer-permafrost interface. After initial failure, active-layer-detachment failures can lead to retrogressive thaw-slumping and localized surficial landslide. Common trigger mechanisms for failure include high summer air temperatures and heavy summer precipitation. A third possible trigger mechanism for slope failure is earthquake occurrence. A geotechnical slope stability analysis was undertaken for an active-layer-detachment failure that had progressed into a retrogressive thaw slump. A safety factor (F _s ) of 1.24 for the natural slope was determined using in situ tested strength parameters. However, the slope would lose stability when either the groundwater level over the permafrost table exceeded 1.42 m or seismic acceleration reached, or exceeded, 0.03?g.     

裂隙各向异性介质2.5维弹性波场数值模拟

研究地震波在各向异性介质中的传播规律是勘探地震学领域的一个重要内容。本文首先讨论了２．５维波动方程，其次，在２．５维空间，用有限元数值模拟方法模拟了裂隙各向异性介质波场，结果用波场切片做了显示。最后对模拟结果做了基本分析，这里讨论的模拟方法也适用于其它类型的得各向异性介。     

造山带与相邻盆地间物质的横向迁移

本文以太行山隆起与相邻华北断陷盆地为例，论述了在大陆岩石圈中造山带与相邻断陷盆地在地球动力学机制上是相辅相成的对立统一体系。当软流圈受力产生波状起伏变形时，在软流圈和上地幔隆起上方，地壳发生减薄并裂陷；软流圈和上地幔拗陷上方，地壳变厚，由脉隆升。造山带遭受物理（化学）风化作用的产物被搬运至相邻断陷盆地，并以逆冲推覆岩片、拆离滑脱构造体系向盆地扩展。断陷盆地的中下地壳物质，则在地幔上隆形成的地幔位势差、密度差和盆地扩张力的共同驱动下，沿向造山带缓倾的拆离滑脱变形带，向山根蠕动流动，以补充因地幔拗陷和山脉隆升造成的重力亏损，从而达到岩石圈四维空间物质的动态调整。     

Progress of Tracing Fossil Fuel CO2 by Radiocarbon in Chinese Cities

The main cause of increase in atmospheric CO₂ concentration is the carbon emissions from fossil fuel combustions and so on. Cities are regarded as the hot spots of carbon emissions. On the basis of obtaining the levels and spatial-temporal variation characteristics of atmospheric fossil fuel CO₂ （CO_2ff）， we can provide scientific data for government policy-making and international negotiations on carbon reductions. In the recent ten years， some important progresses have been achieved in the study of tracing urban atmospheric CO_2ff using ¹⁴C by Chinese scientists. The variation characteristics of urban CO_2ff at different temporal and spatial scales were obtained through the analysis of ¹⁴C in air， tree ring and annual plant samples. Our results show that the northern cities are the key points to reduce carbon emissions， and that the CO_2ff emissions can be reduced simultaneously by controlling atmospheric pollutant emissions， indicating a synergistic emission reduction. It was found that CO_2ff in Xi'an was mainly from local coal-burning emissions with the use of improved WRF-CHEM model and δ¹³C. Finally， the yearly CO_2ff traced by tree-ring ¹⁴C in Xi'an showed similar trends and amplitudes with the statistical data of carbon emissions， which indicates that the ¹⁴C tracing method and statistical method can be mutually validated to ensure the reliability of the data. In order to promote the ¹⁴C trace study to serve the national carbon emission reduction task， we suggest that the urban atmospheric Δ¹⁴CO₂ observation network should be established as soon as possible， and that this study should be enhanced with more scientists involved in it and more financial resources to support it.     

Analyses and calculation facts of the baroclinic term in synoptic-scale motion over tropics

Analyses are made of all terms in the vorticity equation for the atmosphere at low latitudes by using the scale analysis theory, with the result that for synotic-scale motion the baroclinic term, i. e. the twisting term and the vorticity vertical-transport term, approximates in order to the relative-vorticity advection, divergence and β term. With intensified atmospheric disturbance ratios of the β term to others become smaller while the others stay in more or less fixed proportions between them. This statement has been confirmed by the results of 22 typhoons calculated covering a large area in low latitudes. Besides, the baroclinic term for the genesis and development of 6 typhoons over 1979－1980 is calculated and the results ob-tained show that it has significant effect. Finally, the baroclinicity is shown not to be ignored in dealing with synoptics and dynamics of synoptic-scale systems such as typhoons and easterly waves.     

荧光催化动力分析法测定痕量钌

在碱性介质中,痕量Ru对邻羟基苯基荧光酮与H_2O_2的氧化还原反应有催化作用。据此,本文拟定了高灵敏测Ru的荧光催化动力学方法。实验操作简单,Ru的检出限为5×10~(-11)g/ml。     

一种新的非均匀断层模型及其振幅谱的特征

本文提出了一种弯曲断层面的非均匀断裂模型。我们把弯曲断层面简化为锯齿形状,当每个锯齿上的滑动是均匀的,同时具有均匀的位错传播速度时,可以得到问题的封闭形式的精确解。对于不同的齿数、齿倾角和场方位角,计算了体波辐射的振幅谱。研究发现,弯曲断层会使谱曲线出现异常的峰值,异常峰值的位置与齿数有关,随齿数的增加向高频方向移动。齿倾角的变化会引起振幅谱曲线上异常峰附近谱包络线的变化。不同方位的观测点处的振幅谱形状各不相同。仔细地将观测谱与理论谱对比,有可能使人们了解断层面的非平面性质。     

广东河源冲积扇Bms层土壤的特性参数及其与时间的关系

土壤是母岩、气候、生物、地形和时间等综合作用的产物,在其它因素相同的条件下,显示土壤特性的物理化学参数均随着风化时间的增长而有规律的变化。本文初步建立了河源断裂山前地带三级冲积扇中Bms层土壤的pH值、容重、有机质、次生粘土和三水铝石等与冲积扇形成年龄的关系,并依据次生粘土与三水铝石的增长速率对第Ⅲ级冲积扇的形成年龄进行了计算,初步确定了三级冲积扇形成的年代序列     

内蒙狼山地区的控矿构造研究

狼山地区中元古代沉积了一套具拉张型过渡壳性质的岩石建造,并混有含矿火山喷发物质。中元古代晚期褶皱回返过程中,经历了多次断裂作用和褶皱变形。在狼山南东缘,顺层滑动断裂和逆冲推覆构造导致了热液蚀变和混合岩化,促使成矿元素迁移到裂隙发育、有利交代作用的白云石大理岩中富集成矿。狼山北西侧,则由于强烈的褶皱叠加作用,促使矿层在褶皱转折端等有利部位加厚,形成厚大工业矿体。从而提出了东升庙型的断裂控矿模式和霍各乞型褶皱控矿模式。     

用极值顺序统计量对灾害性地震的统计推断

本文引进应用极值顺序统计量推断一个概率分布尾部性质的方法,并介绍了参数估计的方法。文中举例说明如何应用这一理论预测灾害性地震。这种方法比传统极值方法更适用于无季节性变化的数据。