Current developments of research on permafrost engineering and cold region environment: a report of the 8th International Symposium on Permafrost Engineering

The Eighth International Symposium on Permafrost Engineering was held in Xi’an,China,October 2009.The major topics discussed in the symposium included:permafrost engineering (involving design,construction and evaluation);mitigation of frost hazards in the regions affected by seasonally frozen ground;properties of frozen soils,model development and their applications;frost hazards and periglacial environments in mountain and plateau regions;climatic,environmental and cryospheric changes;and permafrost hydrology,cold regions water resources and land uses.The papers submitted to the symposium and lectures during the meeting represented some new developments of research on cold region engineering and environment.Here we summarized the works of the symposium in topics including:Permafrost engineering;General geocryology;Properties of frozen soils:model development and their applications;And climatic,environmental and cryospheric changes.During the symposium,the attendees pointed out that future studies should pay more attention to theoretical study and engineering mechanism study,and also on interaction between climate change and cold region environments and their engineering affects.     

近5年青海省植被覆盖变化的遥感监测

This paper used five years （2001-2006） time series of MODIS NDVI images with a 1-km spatial resolution to produce a land cover map of Qinghai Province in China. A classification approach for different land cover types with special emphasis on vegetation, especially on sparse vegetation, was developed which synthesized Decision Tree Classification, Supervised Classification and Unsupervised Classification. The spatial distribution and dynamic change of vegetation cover in Qinghai from 2001 to 2006 were analyzed based on the land cover classification map and five grade elevation belts derived from Qinghai DEM. The result shows that vegetation cover in Qinghai in recent five years has been some improved and the area of vegetation was increased from 370,047 km^2 in 2001 to 374,576 km^2 in 2006. Meanwhile, vegetation cover ratio was increased by 0.63%. Vegetation cover ratio in high mountain belt is the largest （67.92%） among the five grade elevation belts in Qinghai Province. The second largest vegetation cover ratio is in middle mountain belt （61.80%）. Next, in the order of the decreasing vegetation cover ratio, the remaining grades are extreme high mountain belt （38.98%）, low mountain belt （25.55%） and flat region belt （15.46%）. The area of middle density grassland in high mountain belt is the biggest （94,003 km^2）, and vegetation cover ratio of dense grassland in middle mountain belt is the highest （32.62%）, and the increased area of dense grassland in high mountain belt is the greatest （1280 km^2）. In recent five years the conversion from sparse grass to middle density grass in high mountain belt has been the largest vegetation cover variation and the converted area is 15931 km^2.     

Dynamic Response of Shallow-Buried Small Spacing Tunnel with Asymmetrical Pressure: Shaking Table Testing and Numerical Simulation

A series of shaking table tests were designed and carried out to study the seismic behaviors of a shallow-buried small spacing tunnel with asymmetrical pressure. The key details to shaking table model test, including test equipment, model similarity relation, similarity constant, model box, physical model, layout of transducers, seismic waves, and loading system were presented. The numerical simulation of the shaking table test was also carried out by using a finite element simulation software. The results show that: (1) the Fourier spectrums in the vertical direction and horizontal direction are different at the same measuring point. The structure of tunnel transforms the Fourier spectrum of horizontal direction. (2) The stability of middle rock pillar is poor under seismic wave action. The anchor plays an important role in strengthening the stability of middle rock pillar. The dynamic strain of anchor has accumulative effect. (3) The numerical simulation results are in significant agreement with the shaking table test results. (4) Compared with type of seismic wave, peak seismic wave has a significant effect on acceleration response of tunnel. The peak acceleration response of the tunnel is linear with the peak seismic wave, in the horizontal direction. The peak acceleration response is nonlinear in the vertical direction. (5) The axial force of cross section at arch foot is larger than other position. The shock absorption effect of 10 cm seismic isolation layer is better than 5 and 20 cm.     

沙漠土壤和大气边界层中水热交换和传输的数值模拟研究

为了解沙漠土壤和大气边界层系统中的水分和能量的交换和传输特征，本文发展了一个一维耦合模式，其中包括一个同时考虑土壤中液态水及气态水运动的沙漠土壤模式和一个基于非局地过渡湍流闭合方案的大气边界层模式。用这一耦合模式对沙漠土壤和大气界面的水热交换及沙漠土壤和大气边界层中的水热输送过程进行了模拟，同时与ＨＥＩＦＥ（ＨｅｉｈｅＲｉｖｅｒＢａｓｉｎＦｉｅｌｄＥｘｐｅｒｉｍｅｎｔ）沙漠站的有关资料进行了对比。模拟结果表明约６５％的净辐射能以感热（５０％）和潜热（１５％）的形式提供大气，约３５％的净辐射能以地热流量的形式进入土壤。土壤表层２ｃｍ的范围表现为水热传输的活跃层，水分和温度廓线呈现剧烈的日变化。模拟结果同时表明沙漠土壤中水分传输以气态水为主，如果忽略土壤中的气态水运动，地气界面的水汽通量计算及边界层内的湿度及水汽通量的计算会产生较大的误差     

保安煤矿西翼3煤层开采安全性研究

通过对矿区水文地质条件的分析,认为开采3煤层时的主要充水含水层为顶板砂岩裂隙水和底板奥灰水,以奥灰水最为突出。采用突水系数法及阻水系数法计算煤矿西翼3煤层开采的有效隔水层厚度为37.6m,运用大井法计算工作面开采过程中最大涌水量为98.3m3/h。研究认为：工作面可以进行带压开采,在巷道和工作面开拓中必须在井下施工探放水孔,在富水区进行疏水降压,达到安全开采的目的;开采F20、F35断层附近时应留足防水煤柱,并对奥灰进行疏水降压,以免发生突水事故。     

Progress of Tracing Fossil Fuel CO2 by Radiocarbon in Chinese Cities

The main cause of increase in atmospheric CO₂ concentration is the carbon emissions from fossil fuel combustions and so on. Cities are regarded as the hot spots of carbon emissions. On the basis of obtaining the levels and spatial-temporal variation characteristics of atmospheric fossil fuel CO₂ （CO_2ff）， we can provide scientific data for government policy-making and international negotiations on carbon reductions. In the recent ten years， some important progresses have been achieved in the study of tracing urban atmospheric CO_2ff using ¹⁴C by Chinese scientists. The variation characteristics of urban CO_2ff at different temporal and spatial scales were obtained through the analysis of ¹⁴C in air， tree ring and annual plant samples. Our results show that the northern cities are the key points to reduce carbon emissions， and that the CO_2ff emissions can be reduced simultaneously by controlling atmospheric pollutant emissions， indicating a synergistic emission reduction. It was found that CO_2ff in Xi'an was mainly from local coal-burning emissions with the use of improved WRF-CHEM model and δ¹³C. Finally， the yearly CO_2ff traced by tree-ring ¹⁴C in Xi'an showed similar trends and amplitudes with the statistical data of carbon emissions， which indicates that the ¹⁴C tracing method and statistical method can be mutually validated to ensure the reliability of the data. In order to promote the ¹⁴C trace study to serve the national carbon emission reduction task， we suggest that the urban atmospheric Δ¹⁴CO₂ observation network should be established as soon as possible， and that this study should be enhanced with more scientists involved in it and more financial resources to support it.     

一些硫化物矿物的晶体形貌学研究

论述了辰砂、雄黄、雌黄、辉锑矿、辉铋矿、毒砂、车轮矿、钽锰矿８种矿物的晶体形貌。文中所提供的全部形态测量结果是按Ｖ．Ｇｏｌｄｓｃｈｍｉｄｔ方法严格测量的新资料。     

机载InSAR测绘系统飞行试验报告

干涉合成孔径雷达测量技术是近年来发展起来的一种新技术。机载InSAR测绘系统在国内还处在研制阶段。其测绘能力以及测图精度以前只能从外文资料中了解。为了获取机载InShR测绘系统第一手资料。我们在河北某地进行了机载InsAR测绘飞行试验，并对InSAR数据进行了处理，对其测绘能力以及测图精度进行了分析，给出了试验结论。     

用泻利盐矿和卤水制备硫酸镁工艺探究

以盐田泻利盐矿和卤水为原料,通过兑卤、热溶、结晶法制备硫酸镁。探究了各工艺因素对产物收率及纯度的影响,找到了较佳的工艺条件;在此基础上进行粗镁精制,得到纯度99%以上的硫酸镁。     

Grain-size distribution characteristics of red sandy sediments in Dongjiang River valley, southern Nanling Mountains, during the MIS2 stage

Layer LJ3 of Linjiang stratigraphic section in Dongjiang River valley in the south of the Nanling Mountains is a set of red sandy sediments.Measured by thermoluminescence(TL) dating,it was found to be formed in MIS2-9,500 ± 800 yr to 19,600 ± 1,800 yr B.P.After analy-sis of the grain sizes of the 16 samples(LJ3-100 to LJ3-85) in this layer,it was discovered that(1) The contents of each grain group in dif-ferent samples are similar.(2) The values of Md,Mz,,Sk,and Kg vary from LJ3-100 to LJ3-85 in a narrow range.(3) The segments of each sample in the accumulative curves extend parallel with similar slopes.All the three aspects reveal the Aeolian characteristics of Layer LJ3.Therefore,it is thought that Layer LJ3 consists of red sandy sediments formed in MIS2 in the south of Nanling Mountain,which reflects the arid climate at that time.