重构地质勘查机制迎接矿产资源短缺的挑战

中国地质勘查在过去的50年中,经历了30多年辉煌和近20年的萎缩停顿,虽为我国经济发展做出了重大贡献,但随着社会主义市场经济的逐步建立和严峻的资源短缺形势,地质勘查业的诸多不适应性暴露无遗,其产业效能因此而受到较大影响.针对这一现状,必须准确估量地质勘查业的地位,对我国的地质勘查进行全新的设计和重构.     

水位变化对多空沟屏障远场隔振效果的影响研究

受季节性降雨的影响,雨季和旱季存在明显的水位波动。为分析地下水位升降对多空沟隔振效果的影响,建立了上覆单相弹性层饱和地基中空沟有限元分析模型。模型中考虑了沟中水的作用,算例分析了等沟深和不等沟深多沟屏障、沟壁倾斜多沟屏障和连续起伏地形屏障在不同水位下的远场隔振效果。计算结果与相应单相弹性地基进行对比,结果表明：土体渗透性低时,多数水位下不利于多沟屏障隔振;沟深为0.3LR（LR为R波波长）的三沟屏障通常可获得较理想的隔振效果（75%隔振率）,但屏障在隔振效果最差的共振水位(0.6LR)下,空沟须贯穿上覆干土层才可获得75%隔振率;递减沟深屏障可有效降低上覆土层共振的不利影响;沟深较浅时,沟壁倾角越大,多沟的隔振效果越好,但对较深多沟的影响小;连续起伏的地形景观可作为一种有效的绿色隔振屏障。     

祁连山北坡东段2010—2020年人工增雨试验效果检验评估

使用祁连山北坡中段和东段5—9月面雨量和水文资料,运用非随机人工增雨试验中的序列检验、区域对比、区域双比和区域回归等4种数理统计效果检验评估方法,对2010—2020年在祁连山北坡东段开展的人工增雨作业效果进行检验评估。试验发现：4种效果检验评估方法均证明祁连山北坡东段开展的人工增雨试验为正效果,其中区域对比、区域双比、区域历史回归试验效果检验通过了显著性水平α≤0.10的显著性检验;通过对4种评估检验方法分析,区域历史回归试验方法使用的样本容量较大,避免了人为选择历史相似天气容易引入众多主观偏倚和争议的操作程序,产生的假效果相比其他试验最小、功效最高,可作为最终评估结果,祁连山北坡东段2010—2020年平均相对人工增雨效果为26%。进一步评估了祁连山北坡东段2010—2020年开展大规模人工增雨对石羊河流域生态环境改善的影响,分析发现：石羊河年平均径流量增加了124.6%、民勤蔡旗断面年平均下泄水量增加了124.3%、民勤盆地地下水位上升了2.46 m,干涸近半个世纪的青土湖水域面积持续增大。     

Velocity adjustable TMD and numerical simulation of seismic performance

A new type of velocity adjustable tuned mass damper (TMD) consisting of impulse generators and clutches is presented. The force impulse is generated by a joining operation of electromagnets and springs and MR dampers are used as clutches. Rules for velocity adjustment are established according to the working mechanism of TMD. The analysis program is developed on a VB platform. Seismic response of SDOF structures with both passive TMD and velocity adjustable TMD are analyzed. The results show that (1) the control effectiveness of passive TMDs is usually unstable; (2) the control effectiveness of the proposed semi-active TMDs is much better than passive TMDs under typical seismic ground motions; and (3) unlike the passive TMD system, the proposed velocity adjustable TMDs exhibit good control effectiveness even when the primary structure performance becomes inelastic during severe earthquakes.     

Geomorphic effectiveness of extraordinary floods on three large rivers of the Indian Peninsula

The efficacy of extreme events is directly linked to the flood power and the total energy expended. The geomorphic effectiveness of floods is evaluated in terms of the distribution of stream power per unit boundary area (ω) over time, for three very large floods of the 20th Century in the Indian Peninsula. These floods stand out as outliers when compared with the peak floods per unit drainage area recorded elsewhere in the world. We used flood hydrographs and at-a-station hydraulic geometry equations, computed for the same gauging site or a nearby site, to construct approximately stream-power curves and to estimate the total energy expended by each flood. Critical unit stream power values necessary to entrain cobbles and boulders were estimated on the basis of empirical relationships for coarse sediment transport developed by Williams [Williams, G.P., 1983. Paleohydrological methods and some examples from Swedish fluvial environments. I. Cobble and boulder deposits. Geografiska Annaler 65A, 227–243.] in order to determine the geomorphological effectiveness of the floods. The estimates indicate that the minimum power per unit area values for all three floods were sufficiently high, and stream energy was above the threshold of boulder movement (90 W m^− 2) for several tens of hours. The peak unit stream power values and the total energy expended during each flood were in the range of 290–325 W m^− 2 and 65–160 × 10⁶ J respectively. The average and peak flood powers were found to be higher or comparable to those estimated for extreme palaeo or modern floods on low-gradient, alluvial rivers.     

能源补贴政策及其改革——为减排提供经济激励

The subsidy, as a measure, is widely applied by governments at all levels around the world as a way of policy interventions. However, there are two completely opposite opinions of subsidies on energy and environmental protection. The only reason for subsidy in existence is the internalization of external benefit. The paper firstly examines the energy subsidy policies relevant to climate change mitigation in China and their effectiveness, then points out the deficiency existing in energy conservation policies and renewable energy development policies, and finally suggests that China should exert positive role of subsidy policies and reduce negative effects in promoting climate change mitigation.     

层状侵入体及其韵律层成因

层状侵入体以其独特的韵律结构记录了岩浆的演化分异过程。围绕韵律层理的成因 ,不同学者提出了很多成层机制 ,归纳起来大体有两类 :一类与岩浆流动和动力成层有关 ,包括流动分异、对流成层、化学成因等 ;另一类为非动力成层机制 ,主要有火成堆积、重力分异、压实作用和固化收缩等观点。影响韵律形成的因素很多 ,通常包括岩浆成分、对流作用、扩散作用、热梯度、氧逸度、温度和压力等。在评述这些成层机制和影响因素的基础上 ,结合攀枝花层状侵入体的特点 ,认为该岩体的韵律结构是在岩浆的固化收缩和压实作用下 ,晶体定向生长和自组织排列的结果 ,是二元 (辉石 ,斜长石 )、固 (岩石 )—液 (岩浆 )相转变系统中动量、能量和物种质量的复杂耦合所形成的分形自组织现象。对层状侵入体的进一步研究应集中在加强实验 (尤其是高温高压实验 )、引入非线性分析以及与成矿研究相结合等方面。     

干旱荒漠绿洲紫花苜蓿的节水灌溉及水效益分析——以民勤县为例

通过对民勤绿洲区8个紫花苜蓿品种的节水灌溉技术研究, 分析得出紫花苜蓿在刈割前10d灌溉的平均耗水系数比刈割后灌溉的平均耗水系数降低18.6%, 平均水效益提高23.3%; 采用沟畦小块(面积0.03hm²)刈割前10d灌溉的紫花苜蓿平均耗水系数为0.228kg·g^-1, 平均水效益为4.39kg·m^-3, 平均水经济效益为8.78元·m^-3; 是沟畦小块(0.03hm²)灌溉小麦耗水系数的47.2%, 水生产效益的212%, 水经济效益的309%。不同紫花苜蓿品种间水效益的研究表明, 加拿大Ranger Lander、Kane和新疆大叶苜蓿的水效益明显高于对照品种的水效益。同时, 通过对干旱荒漠区水资源紧缺、水资源有效利用率低以及种植业结构不合理的现状分析, 提出了改革种植业内部粮经饲以往的面积比例65:32:3为可行比例1:1:1, 以大力发展优良品种紫花苜蓿草产业为突破口, 走紫花苜蓿产业化道路最终实现高效节水持续农业的对策。     

有机质含量对淤泥固化效果影响的试验研究

淤泥固化技术是淤泥资源化利用的一个重要方法,而有机质对淤泥固化效果的影响是淤泥固化技术研究中的重要课题。在淤泥固化的试验研究中发现有机质含量对淤泥固化的效果有着显著影响。通过对不同有机物含量的固化试验揭示了该种影响的规律,发现淤泥中的有机质存在着一个极限含量4.3 %,当超过这一极限含量后,有机质量的增加不再对固化效果产生更大的影响。根据这一研究结果,提出了对于高有机质淤泥采用水泥-石膏进行固化的方法。     

The effect of increasing gravel cover on forest roads for reduced sediment delivery to stream crossings

Direct sediment inputs from forest roads at stream crossings are a major concern for water quality and aquatic habitat. Legacy road–stream crossing approaches, or the section of road leading to the stream, may have poor water and grade control upon reopening, thus increasing the potential for negative impacts to water quality. Rainfall simulation experiments were conducted on the entire running surface area associated with six reopened stream crossing approaches in the south‐western Virginia Piedmont physiographic region, USA. Event‐based surface run‐off and associated total suspended solid (TSS) concentrations were compared among a succession of gravel surfacing treatments that represented increasing intensities of best management practice (BMP) implementation. The three treatments were no gravel (10–19% cover), low gravel (34–60% cover), and high gravel (50–99% cover). Increased field hydraulic conductivity was associated with maximized surface cover and ranged from 7.2 to 41.6, 11.9 to 46.3, and 16.0 to 58.6 mm h⁻¹ respectively for the no gravel, low gravel, and high gravel treatments. Median TSS concentration of surface run‐off for the no gravel treatment (2.84 g l⁻¹) was greater than low gravel (1.10 g l⁻¹) and high gravel (0.82 g l⁻¹) by factors of 2.6 and 3.5 respectively. Stream crossing approaches with 90–99% surface cover had TSS concentrations below 1 g l⁻¹. Reducing the length of road segments that drain directly to the stream can reduce the costs associated with gravel surfacing. This research demonstrates that judicious and low‐cost BMPs can ameliorate poor water control and soil erosion associated with reopening legacy roads. Copyright © 2014 John Wiley & Sons, Ltd.