一种新型软钢阻尼器力学性能和减震效果的研究

本文研究了一种新型软钢阻尼器。首先分析了这种阻尼器的力学性能和减震机理，依据试验结果给出了它的恢复力模型，并推导得出了特征参数的表达式和疲劳验算式；研究了阻尼器参数对减震效果的影响，给出了最佳的参数取值范围；算例分析表明该种阻尼器具有很好的减震效果。     

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。     

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.     

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。     

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.     

双排弹性桩隔振屏障对平面SH波的多重散射

提出了一种新的求解任意排列、任意半径的弹性桩对平面SH波的多重散射的理论方法,以解决以往假设单重散射的计算方法中不考虑桩列作为整体屏障从而忽略桩间相互干涉关系的不足,并且可用于分析多排弹性桩对平面SH波的散射性状。在数值计算分析中讨论了散射重数,排间距,桩土剪切模量比,桩数等对双排弹性桩屏障隔离效果的影响,从而对实际工程中利用排桩进行振动污染的治理和屏障隔振设计提出了重要的理论依据。     

仿生草在平湖悬空油管维护中的应用效果

在介绍仿生草技术的主要原理及仿生草的铺设过程基础上,主要探讨了仿生草技术在平湖油管岱山登陆段的应用效果。通过单波束、浅地层剖面仪、侧扫声纳等声学方法探测及人工探摸进行检验,结果初步表明,相对于其他措施,仿生草对悬空管道维护效果较为明显。     

长江下游升金湖湿地保护有效性评价(1989-2019年)

湿地保护有效性是实施湿地保护政策与措施后,湿地生态系统质量、健康与受胁情况的反映,是对保护目标的衡量.生态压力是影响湿地保护目标实现的重要因素,因此可以从湿地生态系统压力、状态和响应角度评价湿地保护有效性.本文以升金湖湿地为研究对象,以0.01°×0.01°经纬格网为评价单元,选择10项负向指标、5项正向指标,通过压力...