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1.
为提高高烈度地震区隧道抗震性能,以某铁路隧道为研究背景,分析3种抗减震措施下隧道不同监测点隧道拱顶沉降、边墙收敛、衬砌结构PGA及最小安全系数,通过对比分析得到最优抗减震措施。结果表明:相比于工况1,工况2隧道拱顶沉降减小10.54%~81.10%,边墙收敛减小13.92%~78.77%,衬砌结构PGA减小31.42%~72.02%,最小安全系数增加18.04%~66.13%;相比于工况1,工况3结构拱顶沉降减小3.04%~18.02%,边墙收敛减小4.70%~32.00%,PGA增加13.95%~27.48%,最小安全系数增加7.49%~30.99%;工况4即“减震层+SFRC衬砌”刚柔并济法,相比于工况1,隧道拱顶沉降减小18.46%~83.98%,结构边墙收敛减小17.54%~85.47%,PGA减小30.00%~69.98%,最小安全系数增加47.95%~83.56%;4种工况抗减震性能由高到低依次为:工况4>工况2>工况3>工况1。研究结果可为隧道软硬围岩交接段抗震设防提供理论参考。 相似文献
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Fishing‐gear restrictions and biomass gains for coral reef fishes in marine protected areas
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Stuart J. Campbell Graham J. Edgar Rick D. Stuart‐Smith German Soler Amanda E. Bates 《Conservation biology》2018,32(2):401-410
Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing‐gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no‐take, hook‐and‐line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no‐take zones) most benefited community‐ and family‐level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community‐level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing‐gear types that affect biomass of a diverse set of reef fish families. 相似文献
4.
李宏规 《中国人口.资源与环境》1992,(1)
人口是人口、资源与环境巨系统中最根本的因素。人口增长过快,将直接加大对资源与环境的压力,并影响人口素质的提高。所以,长期坚持实行计划生育这一基本国策是实现人口、资源、环境协调发展的重要保证。为此,必须要统一认识,增强控制人口的危机感和责任感;实施人口和计划生育目标管理责任制;扎实稳妥地做好农村计划生育工作;齐抓共管,保证人口计划的完成。 相似文献
5.
生态足迹影响因子的定量分析 总被引:2,自引:0,他引:2
蒋莉 《长江流域资源与环境》2005,14(2):238-243
人口的膨胀和人类工业化进程的加剧,使得人类向自然界获取越来越多的资源,同时向环境源源不断的输入废弃物,已经严重超过了自然生态系统的供给能力和环境容量,生态环境日益恶化,水土流失、草场退化、植被消亡、生物多样性锐减、全球变暖等情况已经严重到难以遏制的地步,危及到人类自身的生存。在和平与发展成为世界两大主题的今天,人们越来越关注可持续发展的问题。在现有资料的基础上,利用主成分分析方法,定量地讨论了中国各省(区市)1999年生态足迹大小与其影响因子间的关系。结果表明,生态足迹的大小是各省(区市)的大中型企业个数、全社会固定生产投资等众多因子共同作用的结果,其中总人口和GDP是生态足迹大小的主要影响因子,其因子载荷量分别达到了0.940和0.913。值得一提的是非农业人口与生态足迹的相关系数超过了农业人口,这说明由于消费模式和生活水平等的差异,非农业人口对生态足迹的影响大于农业人口对生态足迹的影响。在此基础上建立了生态足迹影响因子的多元线性回归模型,以期为生态足迹在进行区域可持续发展评价的方法上提供新的思路。 相似文献
6.
可持续旅游是 80年代中期以后提出的关于旅游业发展的新思想。经过十多年的不断拓展深化 ,已经得到世界各国的广泛认同 ,并作为跨世纪旅游业发展的战略指导思想。本文从可持续旅游的由来和对可持续旅游内涵实质的界定角度出发 ,结合可持续旅游实现途径的探讨 ,以井冈山风景名胜区为例 ,对风景区旅游业可持续发展进行了深入的探讨 ,为景区的发展规划提出了战略性构想 ,以期能对井冈山风景名胜区旅游资源的可持续利用和旅游业的可持续发展起到抛砖引玉的作用 相似文献
7.
On-going population growth and resulting domestic demand for water require rapid and effective decision-making as regards groundwater management and control of the various sources of salinization and pollution in Coastal aquifers. Sustainability of water resources for utilization by future generations must therefore be a high priority, not only for the purpose of fulfilling needs for water usage but also for bringing people into harmony with their ambient natural environment.The objective of this paper is to propose an empirical approach for prioritization of the needs involved for sustainable aquifer management. The approach involves a schematic format to:(1) develop a global understanding of an aquifer's hydrological and environmental properties in order to delineate appropriate eco-hydrological scenarios and recommend corresponding operational management activities; and(2) emphasize the importance of educating and increasing the awareness of the population involved as to the need for and viability of socially acceptable measures for sustainable management of groundwater and other resources.The psychologist Abraham Maslow utilized a pyramid to illustrate that until people's most basic needs were fulfilled, higher levels of needs would remain irrelevant. This paper postulates a comparable pyramid prioritizing hydrological needs required for progressing towards sustainable groundwater resources. Two sub-regions of Israel's Coastal aquifer in the Sharon region have been presented as representative areas, each characterized by different stress of exploitation. In assessing these sub-regions situation, specific measures have been recommended for achieving and/or maintaining sustainable groundwater resources in light of the ambient environment, and the level of the population on the pyramidal hierarchy of groundwater needs. 相似文献
8.
日本国土开发利用及对我国的启示 总被引:1,自引:0,他引:1
日本在战后经历了经济高速增长,工业化和城市化快速推进的发展历程,其间土地利用在结构、规模、价格、集约利用等方面发生了巨大变动。本文全面分析了二战之后,日本在经济高速增长、产业结构巨大变动、城市化迅速推进的发展过程中.农业用地、工业用地和城市用地在结构、规模、价格、集约利用程度等方面的特征;日本政府针对经济发展和土地利用的变动和影响。制订的一系列规划调整措施和政策法规体系。通过以上分析,探讨日本在有限的土地资源条件下实现经济高速增长的原因、途径和措施,以及对我国的启示。 相似文献
9.
Ricardo Braun 《Environment, Development and Sustainability》2007,9(4):387-411
The implementation of sustainable development may seem a simple concept when written on paper. However to carry-out long term
actions put forward by the Agenda 21 (AG21) at the local level represents one of the main challenges as municipal governments
in general do not have the capacity to effectively implement the process.
Regional environmental assessment (REA) has shown to be effective in supporting decision-making not only to correct environmental
problems due to past unsustainable social-economic developments but also help local governments to implement sustainable actions.
However this requires long-term investments of AG21 plans and projects. The allocation of regular and consistent financial
resources is one of the main ingredients for the sustainable development process. But traditional plans and projects financed
by national and/or international funds may not be sustainable in the long-term because they become dependent on external funding.
Research demonstrate that innovative economic instruments such as ecotaxes represent a feasible alternative to sponsor local
sustainability because taxes are collected permanently by the government and could be invested in continuous actions. Ecotaxes
experiences have provided important reference to structure a municipal incentive model (MIM) to sponsor AG21’s environmental
plans and projects on a long-term (permanent) basis.
However sustainable development cannot be solely through economic investments. A comprehensive municipal environmental management
scheme (MEMS) has been established to support the incentive model. The scheme seeks not only to improve local institutional
framework but also incentive continuous participation of local stakeholders at all levels of society. Participatory events
and the provision of incentives (educational and financial) are key to motivate society to protect the environment and support
actively the sustainable development process as emphasised in the RIO-92 Conference. 相似文献
10.
重量法测定含动、植物油和矿物油废水应注意的问题 总被引:4,自引:0,他引:4
废水监测中,用重量法测定污(废)水中的动、植物油和矿物油是常用方法之一。为了保证测试结果的准确性,减少误差,提高分析测试质量,作者以多年的实践经验结合塔里木油田采油厂生产污水和餐饮行业生活废水的测定,对测定两种不同含油类废水应注意的问题进行探讨。供同行在实际工作中参考。 相似文献