Stability analysis of membrane‐reinforced curved earth retaining walls,using a multiphase approach

The stability analysis of curved earth retaining walls, stabilized by reinforcing membranes, is investigated by means of a multiphase model developed in the framework of the yield design approach. This model is an extension of that previously developed for soils reinforced by linear inclusions. It combines the advantage of a homogenization approach in terms of improved computational efficiency, with its capability to account for a specific soil–reinforcement failure condition, in a rational and systematic way. Application of this model is performed on the illustrative example of a cylindrical‐reinforced retaining wall by means of the kinematic approach of yield design, which provides upper bound estimates for the retaining wall stability factor. Nondimensional charts are finally presented assessing the influence of relevant parameters such as the curvature of the wall, the length of the reinforcing membranes or the reinforcement pull‐out resistance. Copyright © 2009 John Wiley & Sons, Ltd.     

白城市水稻种植区土壤的地球化学特征与水稻产量的相关性研究

吉林省白城市水稻种植区土壤的地球化学特征研究表明，土壤中的SiO2,TiO2,Al2O3,FeO,MnO和P2O5等主要元素的含量与水稻产量具有正相关性，而CaO和MgO等主要元素的含量与水稻产量呈负相关性。土壤中的稀土元素含量和水稻产量呈正相关性。     

Runoff‐induced sediment yield over dune slopes in the Negev Desert. 1: Quantity and variability

Although extensive data exist on runoff erosion and rates for non‐sandy hillslopes, data for arid dune slopes are scarce, owing to the widespread perception that the high infiltrability of sand will reduce runoff. However, runoff is generated on sandy dunes in the Hallamish dune field, western Negev Desert, Israel (P ≈ 95 mm) due to the presence of a thin (usually 1–3 mm) microbiotic crust. The runoff in turn produces erosion. Sediment yield was measured on ten plots (140–1640 m²) on the north‐ and south‐facing slopes of longitudinal dunes. Two plots facing north and two facing south were subdivided into three subplots. The subplots represented the crest of the active dune devoid of crust, the extensively crusted footslope of the dune, and the midslope section characterized by a patchy crust. The remaining plots extended the full length of the dune slope. No runoff and consequently no water‐eroded sediments were obtained from the crest subplots devoid of crust. However, runoff and sediment were obtained from the mid‐ and footslope crusted subplots. Sediment yield from the footslope subplots was much higher than from the midslopes, despite the higher sediment concentration that characterized the midslope subplots. The mean annual sediment yield at the Hallamish dune field was 432 g per metre width and was associated with high average annual concentrations of 32 g l^?1. The data indicate that owing to the presence of a thin microbiotic crust, runoff and water erosion may occur even within arid sandy dune fields. Copyright © 2001 John Wiley & Sons, Ltd.     

钻井冲洗液对水井出水量影响规律的模拟试验研究及其应用

钻井冲洗液是影响水井出水量的主要因素之一。通过室内模拟试验，发现了不同钻井冲洗液类型和不同洗井方法对含水层渗透性的影响规律，找到了既有较好护壁性又对含水层有较小封堵作用且封堵后易于冲洗的冲洗液，并对聚合物在含水层中的作用机理进行了初步探讨。同时介绍了两个应用实例。     

小麦单产的遥感—气象综合模式研究

本文以北京顺义县为例,以气象因子与垂直植被指数(PVI)作为参数,用灰色模型G(0,2)和逐段订正模型即阶乘模型,建立冬小表遥感信息-气象因子综合模型。计算结果表明,改进后的综合模型其平均精度比单纯的遥感信息模型提高近7％,个别年份达到10％以上。     

A MODEL OF POTENTIAL MAIZE YIELD IN RELATION TO ACCUMULATED TEMPERATURE AND ITS APPLICATION IN ASSESSING THE IMPACT OF CLIMATIC CHANGE

Plant breeding for different maturities plays an important role in agricultural strategies for adaptation to climaticchange.In this paper using the data of ten corn hybrids with early,medium and late maturities and different leaf angles,including erectophile and planophile,observed in Beijing,Yanqing,Tai'an,Gongzhuling of Jilin and Shihezi ofXinjiang,a normal growing function was derived on the basis of the main pattern of accumulated dry matter:W=1/1+exp(8.56-13.52u)In accordance with the function authors built up a model of potential maximum biomass which depends on accumulatedtemperatureB_(max)=100+1.11∑~T_m(kg/mu)(1ha=15mu)The model was applied to estimate the potential corn yield of hybrids with different maturities,and applications ofthe results in assessing the impact of climatic change are discussed.     

The creep of potash salt rocks from Saskatchewan

Summary The results of creep tests on the Esterhazy-and the Patience-Lake-types of potash salt rocks from Saskatchewan, Canada are presented. The investigations involved over 6 years of time-dependent experiments in uniaxial compression using potash from the Rocanville and the Lanigan mines of the Potash Corporation of Saskatchewan. A creep test at a given load would last from 2 to 8 months, with most tests conducted over a 4-month period.Since the yield stress of both types of potash lies between 9 and 11 MPa, there is very little creep below 11 MPa. Between 11 and 13 MPa, creep strain production increases sharply through plastic deformation. Above about 13 MPa, however, plastic creep is dominated by brittle creep caused by microcracking. As a result, the lateral and volume creep strain curves may then display the transient and the steady-state, or all three stages of creep, while the axial strain, which is not affected by microcracking, usually attenuates for the whole duration.Two different interpretations of the results are offered. Identifying the last (the fourth) month of testing with the steady-state model, the stress dependence of the steady-state rate has been established for both rock types. A unimodal rate model for the axial strain and a bimodal model for the lateral strain are suggested. The alternate interpretation proceeds on the assumption that under 13 MPa, both the axial and the lateral strain can be modelled through the power function formulation of transient strain.     

红地球葡萄栽培的气候适应性分析

美国红地球葡萄(RedGlobe)，是我国近几年引进的葡萄新品种，其对气象条件的要求较高。本文分别通过温度、湿度、光照等几个方面分析了红地球葡萄生长的适宜气象条件，以便于今后在葡萄的生产过程中趋利避害。     

Rate of sediment yield following small‐scale volcanic eruptions: a quantitative assessment at the Merapi and Semeru stratovolcanoes,Java, Indonesia

Sediment yields were calculated on the ?anks of Merapi and Semeru volcanoes in Java, Indonesia, using two different methods. During the ?rst year following the 22 November 1994 eruption of Merapi, a sediment yield in excess of 1·5 × 10⁵ m³ km^?2 yr^?1 was calculated in the Boyong River drainage basin, based on the volumes of sediment that were trapped by ?ve check dams. At Semeru, sediment discharges were assessed in the Curah Lengkong River from direct measurements on the lahars in motion and on the most signi?cant stream?ows. The calculated rate of sediment yield during one year of data in 2000 was 2·7 × 10⁵ m³ km^?2 yr^?1. Sediment yields are dominated by rain‐triggered lahars, which occur every rainy season in several drainage basins of Merapi and Semeru volcanoes, mostly during the rainy season extending from October to April. The return period of lahars carrying sediment in excess of 5 × 10⁵ m³ is about one year in the Curah Lengkong River at Semeru. At Merapi, the volume of sediments transported by a lahar did not exceed 2·8 × 10⁵ m³ in the Boyong River during the rainy season 1994–95. On both volcanoes, the sediments are derived from similar sources: pyroclastic‐?ow/surges deposits, rockfalls from the lava domes, and old material from the riverbed and banks. However, daily explosions of vulcanian type at Semeru provide a more continuous sediment supply than at Merapi. Therefore, sediment yields are larger at Semeru. Copyright © 2004 John Wiley & Sons, Ltd.     

Analysis of landslide frequencies and characteristics in a natural system,coastal British Columbia

Two hundred and one debris slides and debris ?ows were analyzed in a 286 km² study area on the west coast of Vancouver Island, British Columbia, Canada. The study area remains essentially untouched by humans and therefore affords a natural setting in which to examine slope processes. Landslides were identi?ed and characterized on aerial photographs from 1:15 000 to 1:31 680, and were then mapped and transferred to a GIS for analysis. Based on detailed landslide surveys, we propose a new method to accurately determine volume of landslides of this type by measured total area. Results indicate average denudation rates of 56 m³ y^?1 km^?2, and higher natural rates of failure than analogous regions in coastal British Columbia. In contrast, the landslide rates are substantially less than those from forested watersheds. Landslide distribution is spatially clustered in air photograph epochs, and we propose intense storm cells within regional events as the causal mechanism. Further, failures occurred preferentially over the West Coast Crystalline Complex (by 1·4 times), a metamorphic assemblage of gabbros, schists and amphibolites, but 1·5 times less often over the Island Plutonic Suite, a granitic intrusive formation. The former result represents a new ?nding, while the latter corroborates ?ndings of previous authors. We examined magnitude–frequency relationships of the data set and present for the ?rst time a strong argument that the rollover effect is not merely an artefact, but is instead a consequence of the physical characteristics of the landslides themselves. We subsequently analyzed magnitude–frequency relationships from two other complete data sets from coastal British Columbia and produced a family of curves corroborating this result. Copyright © 2004 John Wiley & Sons, Ltd.