从概念到立法:中国战略环境评价的回顾与展望

总结了国内10年来SEA在理论研究、技术方法、实践、管理制度等方面的成果、经验、存在问题,最后指出SEA的发展趋势与建议,包括建立覆盖决策链所有环节、贯穿决策全过程的环境评价体系,基于强化规划环评与生态规划的联系提出构建相辅相成的规划与评价体系的建议,以及将SEA作为促进决策的民主化与科学化、全面落实可持续发展战略的重要手段等。     

论山东东营、惠民盆地油田水与油气聚集关系

山东东营、惠民盆地的油源断裂,即沟通生油岩与非生油岩的同生断裂发育区,出现了油田水的高含盐度分布带。它不仅与已知油气藏的分布相一致,而且水的含盐度异常值与石油储量之间呈正相关。笔者以东辛、现河庄和临商油田为例,分析了油田水与油气藏形成的成因和伴生关系,还用相关曲线定量预测了盆地新区石油地质储量,并经钻探证实其可靠性。     

Seismic response of single-column bent on pile: evidence of beneficial role of pile and soil inelasticity

While seismic codes do not allow plastic deformation of piles, the Kobe earthquake has shown that limited structural yielding and cracking of piles may not be always detrimental. As a first attempt to investigate the consequences of pile yielding in the response of a pile-column supported bridge structure, this paper explores the soil–pile-bridge pier interaction to seismic loading, with emphasis on structural nonlinearity. The pile–soil interaction is modeled through distributed nonlinear Winkler-type springs and dashpots. Numerical analysis is performed with a constitutive model (Gerolymos and Gazetas 2005a, Soils Found 45(3):147–159, Gerolymos and Gazetas 2005b, Soils Found 45(4):119–132, Gerolymos and Gazetas 2006a, Soil Dyn Earthq Eng 26(5):363–376) materialized in the OpenSees finite element code (Mazzoni et al. 2005, OpenSees command language manual, p 375) which can simulate: the nonlinear behaviour of both pile and soil; the possible separation and gapping between pile and soil; radiation damping; loss of stiffness and strength in pile and soil. The model is applied to the analysis of pile-column supported bridge structures, focusing on the influence of soil compliance, intensity of seismic excitation, pile diameter, above-ground height of the pile, and above or below ground development of plastic hinge, on key performance measures of the pier as is: the displacement (global) and curvature (local) ductility demands and the maximum drift ratio. It is shown that kinematic expressions for performance measure parameters may lead to erroneous results when soil-structure interaction is considered.     

Reliability of dipole-dipole electrical resistivity tomography for defining depth to bedrock in covered karst terranes

 Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Because of the irregular distribution of pinnacles and cutters on the bedrock surface, uncertainties arise when "hit-or-miss" borehole drilling is used to locate potential collapse sites. A high-resolution geophysical technique capable of depicting the details of the bedrock surface is essential for guiding the drilling program. Dipole-dipole electrical resistivity tomography (ERT) was used to map the bedrock surface at a site in southern Indiana where limestone is covered by about 9 m of clayey soils. Forty-nine transects were conducted over an area of approximately 42,037 m². The electrode spacing was 3 m. The length of the transects varied from 81 to 249 m. The tomographs were interpreted with the aid of soil borings. The repeatability of ERT was evaluated by comparing the rock surface elevations interpreted from pairs of transects where they crossed each other. The average difference was 2.4 m, with a maximum of 10 m. The discrepancy between interpreted bedrock-surface elevations for a transect intersection may be caused by variations in the subsurface geology normal to the transect. Averaging the elevation data interpreted from different transects improved the ERT results. A bedrock surface map was generated using only the averaged elevation data at the transect junctions. The accuracy of the map was further evaluated using data from four exploratory boreholes. The average difference between interpreted and actual bedrock surface-elevations was less than 0.4 m. The map shows two large troughs in the limestone surface: one coinciding with an existing sinkhole basin, while the other is in alignment with a small topographic valley. Because sinkholes were observed at the same elevation interval in similar valleys in the vicinity, the delineated trough may have implications for future land use at the site. Received: 4 January 1999 · Accepted: 8 March 1999     

An accurate time integration method for simplified overland flow models

An accurate time integration method for the diffusion-wave and kinematic-wave approximated models for the overland flow is proposed. The discretization of the first- and second-order spatial derivatives in the basic equation is obtained by using the second-order Lax–Wendroff and the three-point centred finite difference schemes, respectively. For the solution in time, the system of ordinary differential equations, obtained by the linearization of the celerity and of the hydraulic diffusivity by Taylor series expansions, is integrated analytically. The stability and the numerical dissipation and dispersion are investigated by the Fourier analysis. A proper Courant number, and the corresponding time step for the numerical simulations can be established. In addition, the proposed diffusion-wave and kinematic-wave models are straightforwardly extended to the two-dimensional flow. Test cases for both one- and two-dimensional problems, compare the solutions of the diffusion-wave and kinematic-wave models with analytical solutions, with experimental results and with numerical solutions obtained by the Saint–Venant equations. These simulations show that the proposed numerical–analytical models accurately predict the overland flow for several situations, in particular for unsteady rainfall rate and for spatial variations of the surface roughness.     

基于三维四面体模型的西藏资源环境承载力综合评价

资源环境承载力定量评价与综合计量是资源环境承载力研究由分类走向综合的关键技术环节.本文从系统角度出发,提出了"人居环境适宜性分区——资源承载力限制性分类——社会经济发展适应性分等——资源环境承载力警示性分级"的资源环境承载力综合评价的研究思路与技术路线,构建了具有平衡态意义的资源环境承载力综合评价的三维四面体模型,对区...     

咸化湖盆白云岩碳氧同位素特征及古环境意义:以柴西地区始新统下干柴沟组为例

近年来,柴西地区始新统致密碳酸盐岩中的油气勘探获得了重要进展,其中白云岩为最优质的储集岩。系统的岩石学、矿物学和地球化学特征研究表明,该套白云岩主要为泥晶结构,白云石晶间孔广泛发育,孔径多小于1μm。泥晶白云岩的δ13CPDB值变化范围为-4.5‰~0.2‰,平均值为-2.4‰,相对于典型湖相碳酸盐岩偏负,反映了周缘辫状三角洲供给富含轻碳的地表水在一定程度上改变了白云岩的碳同位素组成,且湖水中的溶解碳部分来源于有机质氧化解体产生的CO2,通过改变湖水中溶解碳的碳同位素组成从而间接影响了湖相白云岩的碳同位素组成。泥晶白云岩的δ18OPDB值变化范围为-6.1‰~0.4‰,平均值为-2.6‰,相对于典型湖相碳酸盐岩偏正,明显受咸化湖沉积环境影响。碳氧同位素相关关系投点图及其计算出的盐度、温度数据反映了泥晶白云岩是在准同生阶段、半开放-半封闭的咸化环境下、于水/沉积物界面附近由方解石交代而成的低温白云岩,这类准同生交代成因白云岩在区域上分布较广,且孔径极小的白云石晶间孔抗压实能力强,这一重要发现无论是平面展布上还是纵向深度上均开拓了柴达木盆地致密油勘探的新领域。     

淤泥质软土动态流变特性与流变参数研究

实际调查和理论分析表明,软弱岩土具有流变特性,动态载荷作用加速了软弱岩土的流变行为,成为诱发岩土地质灾害的重要因素和主要动力。在测试分析动载作用下淤泥质软土的流变力学特性基础上,建立了动态黏弹塑性流变力学模型和流变方程,推导出动态流变参数计算式;通过测试,分析了动态剪切作用频率、动态剪切应变、淤泥质软土含水率等因素对动态流变参数影响特性。研究结果对揭示动载作用下淤泥质软土动态流变特性与流变参数影响变化规律,探索软弱岩土突发地质灾害的流变动力学机制等具有一定的理论和现实意义。     

公用微机硬盘信息保护的一种有效方法

介绍一种保护公用微机硬盘信息的有效方法．不仅可以预防各种计算机病毒，更重要的是可以防止人为操作对硬盘信息的破坏。适用于学校等开放性微机实验室的信息安全与保护．     

陕西大理河流域土地利用/覆被变化的水文效应

近年来,土地利用/覆被变化的水文效应研究已成为国际的前沿和重点。在大理河流域,LUCC(包括水土保持措施)对水循环和水量平衡产生了深远影响,该流域LUCC水文效应的研究势在必行。根据研究区1990年代三期土地利用数据分析了LUCC的时空变化特征,采用特征变量时间序列法及降水-径流模型对LUCC水文效应进行了研究。结果表明:流域土地利用类型以耕地和草地为主,近10年来,耕地和草地面积有所减少,而林地和建设用地面积持续增加;流域年径流和月径流演化过程均表现出明显的下降趋势;LUCC及水土保持具有减少流域年径流、汛期流量以及增加枯季流量的作用,相对于降水因素,人类活动对流域水文的作用占主导地位;在1990~2000年期间,主要由LUCC引起的年均径流减少量达2616.6×10⁴ m³,占该期间实测减水总量的62.19%。