稳定崩积锥治理崩岗

本文首先指出了现有崩岗治理方法的不足,然后根据崩岗的侵蚀特点,提出了一种通过稳定崩积锥(坡)来治理崩岗的新方法。     

广东省崩岗侵蚀现状与防治措施探讨

1广东省崩岗侵蚀现状1.1崩岗侵蚀面积及分布广东省是我国崩岗侵蚀最严重的省份之一。根据2004-2005年开展的全省崩岗普查的调查成果,广东省崩岗115 154座,总面积为834.50 km2,占广东省1999年遥感调查水土流失面积12 980.49 km2的6.4%。崩岗主要发生在海拔300 m以下花岗岩和红色     

我国南方崩岗侵蚀现状调查

崩岗是在水力和重力作用下山坡土体受破坏而崩坍和冲刷的侵蚀现象,是沟壑侵蚀的一种特殊形式。崩岗侵蚀不仅破坏土地资源,淤积河道、农田及水利设施,冲毁桥梁、道路、民房,而且给当地生态安全形成巨大威胁,同时也严重制约和阻碍了当地区域经济的发展。为此,开展了大规模崩岗调查,准确地掌握了南方崩岗分布情况、数量和发展趋势,以为开展崩岗治理提供决策依据。     

基于GIS的江西于都崩岗侵蚀空间分布研究

崩岗是沟蚀和重力侵蚀结合的一种特殊形式,是我国南方丘陵区水土流失的一种特殊类型,于都县是江西省水土流失较为严重的县份之一,水土流失面积843.82 km2,中度以上流失占流失面积的64.01%,尤以崩岗侵蚀为强烈。借助Arcmap 10地理信息系统建立了江西于都崩岗侵蚀的数据库及影响崩岗的相关图层,将崩岗分布图层分别与影响图层叠加分析,从而得到研究区崩岗的分布规律。研究表明:于都县有崩岗4 062处,绝大多数崩岗正处于侵蚀发育旺盛期,侵蚀严重,崩岗类型以条型、瓢型、混合型为主,三者占崩岗数量的86.9%。崩岗主要发育分布在海拔200 m左右、坡度10°~30°、花岗岩发育的红壤区域。崩岗在全县23个乡镇均有分布,但在崩岗数量及侵蚀面积均具有北多南少、从西北向东南递减的空间分布特点。     

南方红壤丘陵崩岗不同防治模式探讨

崩岗是我国南方红壤区所特有的一种土壤侵蚀类型,也是最严重的侵蚀类型之一。探索与提炼崩岗防治手段与模式,形成高效、和谐与稳定的崩岗人工-自然生态系统,对实现水土资源的可持续利用与生态环境的可持续维护具有重要意义。在崩岗侵蚀防治中,依据开发利用与生态治理相结合、治沟与治坡相结合、工程措施与植物措施相结合、当前治理与后期管护相结合的基本原则,提出了5种崩岗治理模式,以期对南方崩岗防治起到一定的指导作用。     

桂东南花岗岩崩岗侵蚀区景观生态设计探讨

以桂东南梧州市龙圩区下小河流域花岗岩崩岗侵蚀区为例,以水土美丽绿色空间为基础、小流域生态观光旅游为特色,总体统筹规划设计区域景观空间布局和规划方案,结合生态恢复、经济生产、休闲旅游、文化展示的功能需求,将其划分为生态保护区、景观茶园区、水保科普区、特色花海区、观光农业区、乡村聚落区六大区域。根据研究区地形、植被状况、各类用地性质以及景观资源状况,通过地形改造、植被绿化、梯田建设等一系列工程与生物措施,对崩岗各部分进行生态设计,并从植物、水体、道路、配套设施等方面对崩岗侵蚀区进行空间优化,保护水土资源,发展崩岗生态旅游。将崩岗水土保持治理工作与景观生态设计相结合,在传统的崩岗综合治理模式下,兼顾山地、农田等其他水土流失治理工作,将崩岗旅游与农业观光旅游、乡村旅游相结合,探索更全面的可持续发展崩岗侵蚀区综合治理模式。     

南方崩岗侵蚀机理及治理浅见

崩岗是南方红壤丘陵区生态安全、粮食安全、防洪安全和人居安全的主要威胁。降雨入渗会引起土体的湿胀干缩,增大土体的崩解特性,减小土体的抗剪强度、凝聚力,加重土体,扩大裂隙面,从而使大量土体崩塌,崩岗的最大后退速率可达11. 7 m/a。崩岗综合治理措施布局可概括为"上截、中削、下堵、内外绿化"。如果排水沟或削坡等工程措施不能有效地阻止大量雨水下渗,在一定程度上反而会增强崩岗的发展。通过调查发现,种植生态林可以有效阻止崩岗的发展。因此,建议调整崩岗治理的思路,大力提倡生态修复来进行崩岗治理,在一定程度上也可节省人力、财力。     

基于双变量熵信息法的江西省崩岗侵蚀风险评估

崩岗侵蚀是我国南方地区水土流失的一种特殊类型,但关于崩岗的风险评估方面的研究较少。选择江西省作为研究区域,通过相关因子分析筛选风险评估指标,采用双变量熵信息法计算崩岗发生风险,在此基础上采用专家打分法计算崩岗危害风险,将崩岗发生风险与崩岗危害风险叠加即可得到崩岗侵蚀风险,以此探讨区域尺度崩岗侵蚀风险评估的可行性。结果表明:江西省南部、西部崩岗发生风险较高,东部、北部和中部相对较低;全省崩岗危害风险总体较轻微,在中部危害风险相对较高,但比较零碎;综合发生风险和危害风险后,江西省崩岗侵蚀以中风险为主,占全省总面积的63%以上,较高及以上风险主要分布在中部呈东北至西南向的区域范围内。研究成果可为我国南方地区的崩岗侵蚀风险评估提供参考。     

水土流失崩岗治理的方法与成效

因为气候、天气等原因,安溪县龙涓乡常有崩岗现象的发生,这是外营力的侵蚀作用大于土体抗蚀力的结果。在该地区的土壤结构中,底层的母质风化层慢慢侵蚀沟切透表层以及过渡层,再进入风化母质层,最终致其上覆盖层的倾斜和倒塌。文章结合实际根据崩岗的不同情况采用不同的技术方法,在2013年和2017年国家预算内水土保持重点建设工程,对龙涓乡实施水土流失崩岗治理的方法进行经验总结,为类似工程提供参考。     

鄂东南崩岗崩壁溯源侵蚀特征研究

为科学研究崩岗侵蚀机理,并提出合理有效的崩岗治理措施,采用野外试验与室内分析相结合的方法,对湖北通城县五里镇的两个典型崩岗崩壁溯源侵蚀进行了监测,并分析了相关影响因素。结果表明:崩壁溯源侵蚀是崩岗侵蚀最主要的特征;崩壁溯源侵蚀与降雨量和强雨强度密切相关,但不呈线性关系,同时也与崩岗侵蚀高程和植被覆盖度的变化有关。龛的出现和发展是导致崩壁溯源侵蚀的重要因素,龛越发育,则崩岗发生越快。治理崩岗的关键在于防止发生崩壁溯源侵蚀。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.