GCTS空心圆柱扭剪仪反压饱和试验探究

GCTS空心圆柱扭剪仪是研究土体在循环荷载下的主应力轴旋转的理想仪器。如何使用GCTS空心圆柱扭剪仪对软土空心试样进行反压饱和才能使后续试验结果更精确,探究了以GCTS空心圆柱扭剪仪为试验平台,对空心试样进行了反压饱和的试验方法。总结了空心扭剪仪反压饱和的3种加压方式：手动加压、自动加压和连续加压方式。通过一些试验探究了每种加压方式所对应的合理性参数。确定了适合吹填土的压差为15kPa。确定了孔压稳定的标准为：如果孔压在1min内的变化值小于围压和反压之间压力差的5％,则认为孔压稳定。     

盆地动力学研究综述及展望

沉积盆地是地球系统的浅层组成部分,是壳-幔、岩石圈-软流圈两级圈层相互作用的浅部表现形式。沉积盆地分析不仅可以揭示不同类型化石能源、沉积型层控矿产、砂岩型铀矿等资源的分布规律,为矿产勘探提供直接依据,而且可以为大地构造演化过程、重大构造事件、全球环境变迁及气候演变提供丰富资料和详细证据。当代盆地分析不断从单一沉积学分析拓展到综合分析,从静态要素分析拓展到过程和动力机制分析。盆地动力学研究内容包括3部分,即以沉积学分析为主的盆地充填动力学、以构造地质学分析为主的盆地形成演化动力学和多学科交叉的盆地流体动力学研究。近10多年来,盆地动力学研究在深水沉积学、高精度层序地层学、源-汇系统、源区剥蚀过程及其深部响应、大陆边缘盆地动力学及盆地流体动力学等方面取得了长足的进展。     

贵州空域自动化批复系统

人工影响天气作业(以下简称“人影作业”)的申请与批复是人影作业实施的重要环节,是一项涉及多行业、多环节,对安全性要求极高的技术工作。目前,空中交通日益繁忙,日航班量达1700余次,全省人影作业高炮及固定火箭达480余门,是20 a前的3~4倍,通过电话、甚高频无线电台进行人影作业空域申请的传统工作方式已无法满足目前人影作业空域申报和管理的要求。为提高人影作业的效率,缩短作业申请与批复信息的传递时耗,开发建成了贵州省空域自动化批复系统,实现了人影作业多点同时申请与批复,解决了电话占线等问题。简化了业务流程,缩短了人影作业申请与批复时间,从以往一个申请过程至少需打8个电话缩短到2个电话,实现了禁射区的自动批复,完成了人影工作由传统型向信息化转变,大大提高了人影作业时效。     

The Rumuruti chondrite group

Since 1994, the Rumuruti (R) chondrites have been recognized as a new, well-established chondrite group differing from carbonaceous, ordinary, and enstatite chondrites. The first R chondrite, Carlisle Lakes, was found in Australia in 1977. Meanwhile, the number has increased to 107 (December, 2010). This group is named after the Rumuruti meteorite, the first and so far the only R chondrite fall. Most of the R chondrites are breccias containing a variety of different clasts embedded in a clastic matrix. Some textural and mineralogical characteristics can be summarized as follows: (a) the chondrule abundance in large fragments and in unbrecciated rocks is ∼35–50 vol%; (b) Ca,Al-rich inclusions are rare; (c) the olivine abundance is typically 65–78 vol%; (d) the mean chondrule diameter is ∼400 μm; (e) in unequilibrated R chondrites, low-Ca pyroxene is dominating, whereas in equilibrated R chondrites it is Ca-rich pyroxene; (f) the typical olivine in a metamorphosed lithology is ∼Fa_38–40; (g) matrix olivine in unequilibrated, type 3 fragments and rocks has much higher Fa (∼45–60 mol%) compared to matrix olivines in type 4–6 lithologies (∼Fa_38–41); (h) spinels have a high TiO₂ of ∼5 wt%; (i) abundant different noble metal-bearing phases (metals, sulfides, tellurides, arsenides) occur. The exception is the metamorphosed, type 5/6 R chondrite La Paz Icefield 04840 which contains hornblende, phlogopite, and Ca-poor pyroxene, the latter phase typically occurring in low-grade metamorphosed R chondrites only.In bulk composition, R chondrites have some affinity to ordinary chondrites: (a) the absence of significant depletions in Mn and Na in R chondrites and ordinary chondrites is an important feature to distinguish these groups from carbonaceous chondrites; (b) total Fe (∼24 wt%) of R chondrites is between those of H and L chondrites (27.1 and 21.6 wt%, respectively); (c) the average CI/Mg-normalized lithophile element abundances are ∼0.95 × CI, which is lower than those for carbonaceous chondrites (≥1.0 × CI) and slightly higher than those for ordinary chondrites (∼0.9 × CI); (d) trace element concentrations such as Zn (∼150 ppm) and Se (∼15 ppm) are much higher than in ordinary chondrites; (e) the whole rock Δ¹⁷O of ∼2.7 for R chondrites is the highest among all meteorite groups, and the mean oxygen isotope composition is δ¹⁷O = 5.36 ± 0.43, δ¹⁸O = 5.07 ± 0.86, Δ¹⁷O = +2.72 ± 0.31; (f) noble gas cosmic ray exposure ages of R chondrites range between ∼0.1 and ∼70 Ma. More than half of the R chondrites analyzed for noble gases contain implanted solar wind and, thus, are regolith breccias. The 43 R chondrites from Northern Africa analyzed so far for noble gases seem to represent at least 16 falls. Although the data base is still scarce, the data hint at a major collision event on the R chondrite parent body between 15 and 25 Ma ago.     

Evolution and sedimentology of a channel fill in the sandy braided South Saskatchewan River and its comparison to the deposits of an adjacent compound bar

The depositional stratigraphy of within‐channel deposits in sandy braided rivers is dominated by a variety of barforms (both singular ‘unit’ bars and complex ‘compound’ bars), as well as the infill of individual channels (herein termed ‘channel fills’). The deposits of bars and channel fills define the key components of facies models for braided rivers and their within‐channel heterogeneity, knowledge of which is important for reservoir characterization. However, few studies have sought to address the question of whether the deposits of bars and channel fills can be readily differentiated from each other. This paper presents the first quantitative study to achieve this aim, using aerial images of an evolving modern sandy braided river and geophysical imaging of its subsurface deposits. Aerial photographs taken between 2000 and 2004 document the abandonment and fill of a 1·3 km long, 80 m wide anabranch channel in the sandy braided South Saskatchewan River, Canada. Upstream river regulation traps the majority of very fine sediment and there is little clay (< 1%) in the bed sediments. Channel abandonment was initiated by a series of unit bars that stalled and progressively blocked the anabranch entrance, together with dune deposition and stacking at the anabranch entrance and exit. Complete channel abandonment and subsequent fill of up to 3 m of sediment took approximately two years. Thirteen kilometres of ground‐penetrating radar surveys, coupled with 18 cores, were obtained over the channel fill and an adjacent 750 m long, 400 m wide, compound bar, enabling a quantitative analysis of the channel and bar deposits. Results show that, in terms of grain‐size trends, facies proportions and scale of deposits, there are only subtle differences between the channel fill and bar deposits which, therefore, renders them indistinguishable. Thus, it may be inappropriate to assign different geometric and sedimentological attributes to channel fill and bar facies in object‐based models of sandy braided river alluvial architecture.     

上覆压力及排水条件对吹填软土强度影响

吹填土由于其成分来源及沉积环境不同,性质千差万别。以天津海积软土为土质材料,模拟现场吹填环境,研究了吹填软土强度形成影响因素。试验表明,不同的压力及排水条件对吹填软土强度增长影响较大。当排水条件有利于土体中的水排出时,强度增长明显。上覆压力对土体强度增长的影响通过一定的排水条件得以实现,排水条件差和压力增大时,强度增长缓慢且很小,反之,强度增长快且绝对值大。     

考虑侧填荷载的分离式基础涵洞地基承载力新算法和试验

为了研究涵侧填土对采用分离式基础涵洞地基承载力的提高效应,先结合基底土体的受力特点,进行受力分析,建立计算模型,构建求解分离式基础地基极限承载力的算法,给出承载力表达式。然后在相似理论的指导下,设计了5组模型,试验模拟粉质黏土地基受荷变形直到破坏的全过程,绘出荷载-沉降曲线,测得涵侧填土高度为0、4、8、12、16 m时的地基极限承载力。试验发现:随着侧填土高度的增加,承载力显著提高,当填土为12 m时已达到885 kPa;但提高幅度表现出非线性特性,先从18.42%增加到36.11%,然后减小到3.39%;当填土达到16 m时承载力达到915 kPa且不再增加;同时发现使用本文算法与试验实测值的误差小于10%,可以考虑用此算法计算分离式基础涵洞的地基极限承载力。继而得出结论:当涵洞地基沉降满足设计要求时,涵侧填土显著提高了地基承载力,节约工程造价,且提高的幅度先增加后减少,当达到16 m时地基承载力便逐渐趋于915 kPa。     

基于改进的Bresenham圆快速填充算法

为克服现有圆填充算法效率低的缺点,提出一种快速圆填充算法。算法基于圆的对称性,利用圆弧离散轨迹所具有的特性,分别绘制半径由0依次增加一个像素点,直到变为给定半径r的多个圆,同时找出并填充其中的漏点。最后达到快速填充整个圆的效果。     

Heating rate dependency of petroleum-forming reactions: implications for compositional kinetic predictions

The generation of bulk petroleum, liquid and gaseous hydrocarbons from the Duvernay Formation was simulated by heating immature kerogens in a closed system (MSSV pyrolysis) at four different heating rates (0.013, 0.1, 0.7 and 5.0 K/min). Using the established parallel reaction kinetic model, temperature and compositional predictions were tested to be suitable for geological conditions by comparing the laboratory results with natural changes in source bitumens and reservoir oil maturity sequences from the Duvernay Formation. In the case of bulk liquid and gaseous hydrocarbons, the above kinetic calculations can be considered valid because their maximum yields are independent of laboratory heating rates. In contrast, the contents of paraffins, aromatics and sulfur compounds show a pronounced heating rate dependence. Extrapolated to geological heating rates, the compositional predictions are consistent with the bulk composition of natural products in the Duvernay-petroleum system showing an increase of paraffinicity and hydrogen content. In contrast to that, the “hump” decreases with decreasing heating rate, a trend which is confirmed by the low amounts of unresolved compounds in natural high maturity products. Because of these heating-rate dependent compositional changes, geological predictions of natural molecular composition by the commonly used kinetic models are not suitable.     

筑堤土防渗性状试验研究

结合淮河入海水道河道工程,通过渗透变形试验确定了筑堤土料的渗透变形型式、临界水力坡降和允许坡降,同时指出了采用泓道开挖土筑堤的施工控制措施、质量要求和防渗措施。