Architecture of coastal and alluvial deposits in an extensional basin: the Carboniferous Joggins Formation of eastern Canada

Abstract The Joggins Formation was deposited in the Cumberland Basin, which experienced rapid mid‐Carboniferous subsidence on bounding faults. A 600 m measured section of coastal and alluvial plain strata comprises cycles tens to hundreds of metres thick. The cycles commence with coal and fossiliferous limestone/siltstone intervals, interpreted as widespread flooding events. These intervals are overlain by coarsening‐upward successions capped by planar‐based sandstone mounds, up to 100 m in width that represent the progradation of small, river‐generated delta lobes into a standing body of open water developed during transgression. The overlying strata contain sand‐rich heterolithic packages, 1–8 m thick, that are associated with channel bodies 2–3 m thick and 10–50 m wide. Drifted plant debris, Calamites groves and erect lycopsid trees are preserved within these predominantly green‐grey heterolithic sediments, which were deposited on a coastal wetland or deltaic plain traversed by channel systems. The cycles conclude with red siltstones, containing calcareous nodules, that are interbedded with thin sandstones and associated with both single‐storey channel bodies (1–1·5 m thick and 2–3 m wide) and larger, multistorey channels (3–6 m thick) with incised margins. Numerous channel bodies at the same level suggest that multiple‐channel, anastomosed river systems were developed on a well‐drained floodplain. Many minor flooding surfaces divide the strata into parasequences with dominantly progradational and aggradational stacking patterns. Multistorey channel bodies are relatively thin, fine grained and modestly incised, and palaeosols are immature and cumulative. The abundance and prominence of flooding surfaces suggests that base‐level rise was enhanced, whereas the lack of evidence for abrupt basinward stepping of facies belts, coupled with the absence of strong fluvial incision and mature palaeosols, suggests that base‐level fall was suppressed. These architectural features are considered to reflect a tectonic architectural signature, in accordance with the high‐subsidence basinal setting. Evidence for restricted marine influence and variation in floral assemblages suggests modulation by eustatic and climatic effects, although their relative importance is uncertain.     

A bilinear approximation of the surface relief in terrain correction computations

A new method is presented for the computation of the gravitational attraction of topographic masses when their height information is given on a regular grid. It is shown that the representation of the terrain relief by means of a bilinear surface not only offers a serious alternative to the polyhedra modeling, but also approaches even more smoothly the continuous reality. Inserting a bilinear approximation into the known scheme of deriving closed analytical expressions for the potential and its first-order derivatives for an arbitrarily shaped polyhedron leads to a one-dimensional integration with – apparently – no analytical solution. However, due to the high degree of smoothness of the integrand function, the numerical computation of this integral is very efficient. Numerical tests using synthetic data and a densely sampled digital terrain model in the Bavarian Alps prove that the new method is comparable to or even faster than a terrain modeling using polyhedra.     

斜向坡变形破坏机制的数值模拟研究

本文讨论了斜向坡的旋转式变形和破坏机制，用有限元法计算了此种斜坡中的剩余下滑力的分布方式，并以此来解释在滑动过程中发生一定旋转的原因；论文还运用离散元法，模拟了此种滑坡的滑动过程。     

露天矿边坡实用型专家系统PESOPS V1.0的设计与应用

结合边坡工程和岩质边坡普遍存在的问题，建造了一个露天矿边坡实用型专家系统ＰＥＳＯＰＳ Ｖ１．０。介绍了滑坡预报子系统的原理和方法，通过应用实例表明该子系统适用性强，预报可靠、使用方便。     

松江河电厂小山水电站导流洞出口边坡稳定性分析

小山水电站导流洞出口边坡其地质结构为下部中侏罗世安山岩（αＪ２），其上覆盖了第三纪末第四纪初的玄武岩（βＮ～Ｑ），两者间为不整合接触，不整合面夹有０．１～０．６ｍ厚的粘土状及碎石粘土状夹层，产状倾向河床，倾角±２５°。在上覆玄武岩层中见有高倾角的宽张裂隙带，与不整合面一起构成松动岩体，不整合面为底滑面。通过边界条件的分析和稳定计算，松动岩体的抗滑系数Ｋ＝３．１０２，边坡是稳定的。在施工过程中采取了相应的安全保护措施，导流洞出口提前２８ｍ进洞，节约挖方量６００００ｍ３，提前了工期。经三年多的施工到运行，边坡无异常变化，表明该项优化设计是可行的。     

多年冻土区铁路路基病害整治

The paper analyses the treatment measurements of railway roadbed main diseases in permafrost regions. Taking lessons from the diseases finally the mature experiences of treatments are offered.     

水布垭面板堆石坝的三维弹塑性数值分析研究

在建的清江水布垭面板堆石坝高达233 m,是目前同类坝型中最高的.采用MSC.Marc非线性有限元程序,发展了三维子模型法,对该坝进行了三维弹塑性有限元仿真分析,模拟了面板的分缝、坝体材料分区、填筑及蓄水过程,采用双屈服面弹塑性模型模拟堆石体的变形特征.根据数值分析的结果,对坝体和面板的应力变形分布规律进行了探讨.     

四川某矿山边坡失稳机理及稳定性评价

四川某矿山开采边坡迄今已有30余年,随采区规模的逐渐扩大,在矿区南坡构成一典型的顺层开挖边坡,因矿层中夹有不同数量的软弱夹层,在边坡前缘破坏坡角、并加上降雨及爆破振动影响,时常发生颁层滑坡,不仅给矿山人民生命财产带来严重危害,而且也严重制约矿山的正常发展。通过对典型开挖边坡所在部位的工程地质条件凋查,在确定影响边坡稳定的主要控制因素和边界条件的基础上。考虑四种工况条件下的稳定性分析和评价,为矿山下一步施工提出了较为合理的开挖方案。     

Correcting method of eddy covariance fluxes over non-flat surfaces and its application in ChinaFLUX

Although Eddy Covariance (EC) technique is one of the best methods for estimating the energy and mass exchanges between underlying surface and atmosphere in micrometeorology, errors and uncertainties still exist without necessary corrections. In this paper, we will focus on the effect of coordinate system on the eddy fluxes. Based on the data observed over four sites (one farmland site, one grassland site and two forest sites), the effects of three coordinate system transforming methods (Double Rotation-DR, Triple Rotation-TR and Planar Fit-PF)on the turbulent fluxes are analyzed. It shows that (i) the corrected fluxes are more or less than the uncorrected fluxes, which is related mainly to the sloping degree of surface, wind speed and wind direction; and (ii) pitch angle has a sinusoidal dependence on wind direction, especially in the regular sloping terrain; and (iii) PF method is something like the simplification of TR or DR,and there are not obvious distinctions in correction in sloping grassland and flat farmland, but PF method is not suitable for uneven and irregular forest sites.     

Lame surfaces as a generalisation of the triaxial ellipsoid

In modern geodesy the triaxial ellipsoid as a generalisation of the ellipsoid of revolution has a significant position in studying the figure of the Earth. Lame surfaces represent a generalisation of the triaxial ellipsoid. The following paragraphs are devoted to curvatures of the Lame surfaces.