征地区片综合地价与土地城市化的空间耦合分析——以北京市为例

基于征地区片综合地价分析土地价格与土地城市化的速率和强度的空间耦合关系,研究结果表明,在时间和空间尺度上,土地价格与土地城市化的速率和强度存在明显的相互关系,这一耦合作用形成了土地城市化在空间上的分异性状.作为与土地城市化存在空间耦合关系的土地价格可以作为引导土地城市化速度、强度和空间形态的有效调控手段.通过对土地价格的影响,可以引导土地城市化在空间上和时间上达成合理的演替趋向.     

长江中游武汉-九江河段河道形态及水动力学特征

Based on measured hydrological data by using ship-mounted Acoustic Doppler Current Profiler (ADCP) instrument, we analyzed shapes of river cross sections of the middle Yangtze River basin (mainly focusing on Makou and Tianjiazhen river reach). Hydrodynamic properties of river channels were also discussed. The research results indicate that nonlinear relationships can be identified between river-width/river-depth ratio (W/D ratio), sizes of cross section and mean flow velocity. Positive relations are detected between W/D ratio and mean flow velocity when W/D<1; and negative relations are observed when W/D>1. Adverse relationships can be obtained between W/D ratio and cross-section area. Geomorphologic and geologic survey indicates different components of river banks in the wider and narrower river reaches respectively. These may be the main driving factors causing unique hydrological properties of river channels in the middle Yangtze River basin. Narrower river cross sections tend to raise water level in the upstream river reach near narrower river channel, giving rise to backwater effects. River knots can cause serious backwater effects, which is harmful for flood mitigation. However river knots will also stabilize river channel and this will be beneficial for river channel management. The results of this paper may be helpful for flood mitigation and river channel management in the middle Yangtze River basin. Foundation: National Natural Science Foundation of China, No.40701015; Key Project of National Natural Science Foundation of China, No.40730635 Author: Zhang Qiang (1974–), Ph.D and Associate Professor, specialized in natural hazards and climatic changes, hydrologic statistics, floods and fluvial geomorphology.     

准噶尔盆地南缘三叠纪—侏罗纪之交的古气候*

准噶尔盆地南缘的郝家沟剖面三叠系—侏罗系连续发育,是研究三叠系—侏罗系界线及相关地质问题的重要剖面。孢粉分析发现,上三叠统郝家沟组以气候适应范围较宽的裸子植物花粉占优势,而在下侏罗统八道湾组下部主要适应温暖湿润气候的蕨类植物孢子含量明显增高,在组合中常占据优势地位,说明研究区早侏罗世气候比晚三叠世更为潮湿。沉积岩有机碳同位素分析结果显示,在剖面八道湾组下部的δ¹³C值总体低于-24.5‰,形成两次明显的负向偏移,同时采集的丝炭样品的分析结果也证明δ¹³C在八道湾组下部具有明显负向偏移。根据现代湖泊沉积有机质碳同位素与气候关系的研究成果,沉积有机质稳定碳同位素负偏是气候温暖潮湿化的反应,支持了孢粉研究的结果。以上表明,研究区侏罗纪之初的气候比晚三叠世更加炎热潮湿。     

珍惜黄河湿地这片带露的“绿”叶——对黄河兰州段湿地情况的调查及保护建议

本文就如何珍惜兰州黄河湿地,研究了黄河兰州段湿地的分布状况及人类活动带来的影响,分析了黄河兰州段湿地面临的主要威胁,提出了恢复保护黄河兰州段湿地的对策建议和建设兰州湿地科普示范公园的设想。     

Persistency of flow patterns in a water repellent sandy soil – Conclusions of TDR readings and a time-delayed double tracer experiment

On a former waste water disposal field with water repellent sandy soil under grass vegetation we analyzed the persistency of flow patterns on a 150 m × 25 m plot by (i) continuous TDR-measurements on a 2 m × 1 m transect combined with seasonal soil moisture sampling campaigns, and (ii) a time-delayed double tracer experiment on a second 3 m × 1 m transect. Here, we applied bromide under wettable soil conditions in spring and chloride under water repellent soil conditions in autumn. At the end of the tracer experiment, after a travel time of 328 days for Br and 87 days for Cl, respectively, the transect was excavated and sampled in high spatial resolution. Tracer concentration, water content, water drop penetration times (WDPT), and soil organic matter content (SOM) of each sample were analyzed in order to characterize flow patterns. The TDR readings were used to predict the effective cross section (ECS) of subsurface flow and flow shifts over the season.During summer, when ECS is low and consecutive precipitation events occur, flow paths – once created – persist over time. However, over longer times (from autumn to autumn), the spatial arrangements of the flow paths can change completely. The Cl distribution showed typical fingering structures with high concentrations in the less water repellent flow paths. In contrast, Br was found mostly in the dry, hydrophobic areas indicating that it was transported before the soil became water repellent. Consequently, the flow patterns generated in spring and early summer differ completely from those in autumn and winter because of water repellent structures established during the vegetative period. These structures could be identified using a critical water content (θ_crit) concept, considering both soil water content and SOM.As not all soil parts being active during to season, four flow categories could be identified: about 10% permanent (=stable flow paths), 45% periodic (i.e. water repellent in summer), 40% occasional (water repellent in summer and autumn), and 5% permanent water repellent.     

黄土覆盖的阶地陡坎附近渭河断裂活断层探测

陕西咸阳渭河北岸窑店、石何杨、杜家堡渭河断裂活断层探测结果表明,对于有黄土覆盖的、与阶地陡坎重合的活断层探测,要综合采用地形地貌分析、浅层人工地震、钻探和探槽等方法进行。特别是对于钻孔探测,要深、中、浅孔结合。首先用中、深孔确定断层在深部的位置,再用浅孔确定断层在近地表的位置和活动性。由于河流侵蚀,阶地陡坎区的河流相沉积地层是倾斜的,风成的古土壤层披盖在已有的倾斜地层上亦呈倾斜状态,因此,用以上地层判断断层的位置和活动量时,钻孔孔距一定要小,以2～3m为宜,孔距太大,会把侵蚀形成的已有陡坎高度加入断层的错距中,严重放大断层的错动量。探测结果表明,渭河断裂在窑店、石何杨、杜家堡等处与Ⅲ级阶地陡坎重合。该断裂在阶地陡坎上的活动量很小,错断晚更新世第1古土壤层1～2m,远小于2个阶地面的高差。可见,以前认为S1错距4.8m、17.94m是不准确的。     

贵州乐康剖面茅口阶-吴家坪阶碳同位素组成变化及峨眉山大火成岩省的响应

随着精细年代学研究的发展,越来越多的证据表明地幔柱作用下的大火成岩省和地质历史时期的生物绝灭之间有着密切的联系。我国西南地区峨眉山溢流玄武岩省是目前我国惟一被国际认可的大火成岩省,为了更好地证明峨眉山大火成岩省与同期生物、环境变化之间的关系,选择贵州望谟乐康剖面石灰岩开展了碳同位素组成研究。结果表明,在峨眉山地幔柱作用之前的茅口阶碳同位素组成显示出较高的正值(δ13C=5.2‰～4.0‰);茅口阶顶部至领薅组第一段δ13C值主要落在2‰～4‰范围内,其时序上对应于峨眉山玄武岩主喷发之前的区域穹状隆升时期;之后由于峨眉山大火成岩省有关的大规模火山作用导致低值碳源加入,当时缓慢复苏的生物作用造成的碳同位素组成增加远不能抵消火山作用造成的碳同位素组成降低,导致期间碳同位素组成明显降低(变化于0‰～2‰范围),并出现负漂移。该剖面碳同位素组成的变化为峨眉山地幔柱作用对生物和环境效应的研究提供了重要信息。     

证据权法在三江北段铜金矿床成矿预测中的应用研究

在仔细分析三江北段区域地质成矿背景的基础上,建立了该区的地质、物探、化探、遥感和矿床(点)数据库,优选了36个与铜金矿床有关的证据层.应用证据权模型对该区进行成矿预测研究分析,认为研究区内主要存在8个对铜金矿床形成有利的成矿区,这一研究对三江地区今后的矿产资源预测与评价具有重要的参考价值.     

不同截面型式的核电取水隧洞抗震分析及优化设计

结合巴基斯坦某核电工程,将3种隧洞断面型式运用到巴基斯坦卡拉奇核电取水隧洞模型中,采用时程分析方法,对两种不同的工况并考虑隧洞内水压力及支护作用,运用有限差分软件实现了地震响应计算,并利用计算结果对截面进行优化设计.结果表明:圆形截面型式在两种工况下弯矩和剪力值均小于其余两种截面型式;三者内力分布规律基本相似,部分区域...     

指数函数模量成层地基上变截面坝的随机地震反应分析

利用剪切梁理论推导出了指数函数剪切模量成层地基上变截面坝的自振频率方程及任意阶振型函数的解析表达式,在此基础上用振型叠加原理分别给出了地基和变截面坝的地震反应解析表达式.利用随机振动理论,并基于基岩输入地震加速度的功率谱密度函数(白噪声谱和过滤白噪声谱),研究了地基和变截面坝对地震的随机动力响应问题.数值计算表明:①在白噪声谱的情况下,土层和变截面坝的最大期望反应均有别于过滤白噪声谱时的相应值;②平稳输入与输出时地基和变截面坝的最大期望反应与平稳输入非平稳输出的相应值很接近;③平稳输入过高地估计了土层和变截面坝的随机响应.