Consolidation of double‐layered ground with vertical drains

Vertical drains are usually installed in subsoil consisting of several layers. Due to the complex nature of the problem, over the past decades, the consolidation properties of multi‐layered ground with vertical drains have been analysed mainly by numerical methods. An analytical solution for consolidation of double‐layered ground with vertical drains under quasi‐equal strain condition is presented in this paper. The main steps for the computation procedure are listed. The convergence of the series solution is discussed. The comparisons between the results obtained by the present analytical method and the existing numerical solutions are described by figures. The orthogonal relation for the system of double‐layered ground with vertical drains is proven. Finally, some consolidation properties of double‐layered ground with vertical drains are analysed. Copyright © 2001 John Wiley & Sons, Ltd.     

可持续发展进程中的政府能力建设

可持续发展作为现代化建设的两大战略之一 ,对我国政府的能力提出了挑战。可持续发展战略的实施 ,要求加强政府的作用 ,将政府建设成为强有力而又廉价的政府。为此 ,我国政府应从加强政府的财政汲取能力建设、强化中央政府协调地区发展的能力 ,加强政府调控能力建设、强化中央政府协调当前利益和长远利益、经济利益与生态效益的能力 ,并从根本上转变政府职能、精兵简政、建设廉价高效的政府等方面着手来提高我国政府推进和实施可持续发展战略的能力     

Carbonate aeolianites of western Saurashtra,India: experimental decipherment of the depositional mechanisms

Granular carbonate deposits of Late Pleistocene to Early Holocene age, commonly referred to as ‘miliolite limestone’, occur in a linear belt, parallel to the southern coast of Saurashtra, India. In the present study area these carbonate deposits are found in select valleys between ridges and mounds of pyroclastic material present in the Deccan trap plateau. Two different depositional histories have been proposed for these sediments. The presence of marine bioclasts led to the postulation of a marine origin for these deposits. The second school of thought propounded redeposition of the coastal sediments by aeolian processes. Although a few features could not be explained by the proposed aeolian model, critical comparison of these two views favoured the aeolian origin. The mode of occurrence, lithological and structural attributes, and microscopic evidence presented here, also support a possible aeolian origin for these deposits. Experimental observation indicates that these carbonate aeolianites represent backflow deposits, which accumulated because of the flow separation caused by the presence of topographic highs. The conspicuous concave‐up geometry of the deposit conformed to the shape of the separation bulb. In view of the inferred depositional mechanism, the disposition of the deposits and the signature of the palaeoflow direction suggest that the carbonate particles were derived from the north‐western coast of Saurashtra by strong south‐easterly winds. Massive granular carbonates with outsized basement clasts appear to be the product of avalanching of granular material from the higher contours because of oversteepening of the primary deposit.     

Tidal and seasonal controls in the formation of Late Miocene inclined heterolithic stratification deposits, western Amazonian foreland basin

Upper Miocene strata in the Acre sub‐basin, Brazil, consist dominantly of various types of inclined heterolithic stratification and pedogenic horizons. These strata were sedimentologically and ichnologically described to: (i) study different temporal controls responsible for inclined heterolithic stratification generation and their variation in a distal–proximal trend; and (ii) delineate the depositional setting. For this purpose, nine representative outcrops were sedimentologically and ichnologically studied, and their facies associations described. Thickness variations of the heterolithic strata of various orders (lamina, lamina bundles and beds) were analysed by statistical methods (Fourier transform). The deposits were interpreted as tidally and seasonally influenced estuarine or delta‐related and continental strata. The inclined heterolithic stratification deposits represented vastly different settings ranging from tidally dominated, brackish‐water ichnofossils‐bearing channels to seasonally controlled, articulated Purussaurus (a freshwater alligator) fossil‐bearing channels. Several time cycles were distinguished in the strata, including semi‐diurnal, fortnightly and seasonal. Tidal imprint was best observed in low‐energy brackish‐water settings, whereas seasonal rhythmicity was distinguishable throughout the depositional system. However, the latter was most apparent in riverine channels proximal to the inferred fluvio‐tidal transition. The different temporal controls commonly had distinguishable impact on sedimentological and ichnological properties in the studied sediments. The differing properties included: (i) the degree and nature of lateral variability with respect to lithology and bedforms in inclined heterolithic stratification; (ii) the lateral continuity of inclined heterolithic stratification; (iii) the nature of sedimentary contacts between the inclined heterolithic stratification members; (iv) thickness variation of inclined heterolithic stratification members within a set; (v) the cyclicities observed in inclined heterolithic stratification series; (vi) the degree of bioturbation; (vii) the types of trace fossils observed; and (viii) the distribution of bioturbation in adjacent inclined heterolithic stratification members.     

确定连续系统参数的时域方法

提出一种确定连续系统参数的时域方法。该方法利用方波输入和系统稳定性，离析出输出采样信号与结构参数的内在联系，推导出确定连续系统结构参数的算法．指出该算法与辨识方法相结合，可实现对含随机干扰的连续系统结构参数的估计．     

Cycladophora davisiana (Radiolaria) in the Okhotsk Sea: A key for reconstructing glacial ocean conditions

Cycladophora davisiana, a radiolarian species dwelling at mesopelagic depths, is known as a representative glacial fauna due to its unique distribution during glacial periods. In the present ocean, abundant production of C. davisiana is only observed in the Okhotsk Sea, indicating an adaptation of C. davisiana for seasonal sea-ice covered conditions. We found pronounced abundant production of C. davisiana during the early to middle Holocene in the Okhotsk Sea, suggesting more favorable conditions for C. davisiana than the present Okhotsk Sea. In order to clarify the reason, oceanographic conditions during the Holocene were reconstructed based on biomarkers, lithogenic grains including ice-rafted debris (IRD), biogenic opal, and total organic carbon (TOC) in two sediment cores from the Okhotsk Sea. These indicators suggest that the pronounced C. davisiana production may be attributed to: 1) a supply to mesopelagic depths under intensified stratification of fine organic particles derived from coccolithophorids, bacteria, and detrital materials; and 2) cold, well-ventilated intermediate water formation.     

Comparison between zooplankton data collected by the Continuous Plankton Recorder survey in the English Channel and by WP-2 nets at station L4, Plymouth (UK)

Zooplankton sampling has been carried out by the Continuous Plankton Recorder (CPR) survey since the 1930s enabling the study of long-term changes in plankton populations, the elucidation of seasonal patterns of abundance, and more recently providing zooplankton biomass estimates for ecosystem models. Data for zooplankton abundance collected by CPR tows in the Western English Channel (between 1988 and 1998) were compared to vertically integrated samples collected from station L4 off Plymouth, UK. Comparisons were made for locally abundant copepods (including Acartia, Calanus, Para/Pseudocalanus, Centropages, Oithona and Temora) collected by CPR and WP-2 nets. All dominant species recorded at L4 were also common to the CPR data. However, the position of the taxa in the two datasets was not equivalent. Seasonal cycles revealed by CPR data were significantly similar to those recorded throughout the water column at L4 for most taxa. However, absolute levels of abundance differed for the two datasets: abundances were underestimated by CPR samples when compared to those of vertically integrated samples by a factor of between 2 and 35, with the exception of Centropages. The differing mesh sizes (200 and 270 μm) of the WP-2 net and CPR mesh could only partially explain these differences in abundance, implying that the behaviour of individual taxa and their depth in the water column also influenced the abundance recorded.     

悬对沙Mellor-Yamada海洋边界层模型计算结果的影响

为了分析海洋水体垂向水流紊动及紊动交换情况而采用了一维的海洋边界层模型(Mellor-Yamada)并利用数值实验的方法对悬沙、盐度、温度等数据进行分析。原模型未将悬沙考虑在内，本文试将它引入进去探讨由于它的存在对紊动混合特性的影响。2000年4月，Mellor将最初的模型引入了依赖于Richardson数的紊动动能耗散率。本文通过比较具有悬沙和不具有悬沙两种情况下的速度、温度和盐度垂向分布随时间的变化，分析讨论由于悬沙的存在所引发的密度层化对紊动混合作用的影响，并发现悬浮泥沙抑制了部分模拟时间的紊动混合作用。     

Application of wavelet transforms to the decoupling of free-roll decay data

This study presents the results of the decoupling of a free-roll decay test by wavelet transforms. A free-roll decay test was performed to determine the coefficients of damping terms in equations of motion. No motion of the model was restricted during the experiment. A slight yaw motion was found while the model was in the free-roll decay motion. It was necessary to extract a pure roll motion from the experimental data. Wavelet transforms were applied to the signals to extract the pure roll motion. The results were compared to those found through the Fourier transform. Discrete wavelet transforms were able to efficiently decouple the test signals, while the continuous wavelet transform and the Fourier transform could not.     

渤黄东海混合层化演变规律的研究进展

较详细地综述了渤黄东海混合层化演变过程与规律的研究进展情况，主要包括：混合和层化过程的分布规律与季节变化特性，采用水温垂直剖面自相关函数的半经验预报模式，动力学和热力学的数值预报模式。