岩石坚硬程度对核电厂地基-基础地震响应特征的影响分析     

吕涛  杨球玉  耿学勇  陈立伟  杨立建  李海波 《岩土力学》2010,31(4):1319-1325

考虑核电厂地基-基础的动力相互作用,应用显式动力有限差分法分析了地震作用下极软岩、较软岩、坚硬岩上核电厂建筑结构基础的地震响应特征,比较了岩石坚硬程度对基础加速度反应谱的影响。研究表明：随着岩石坚硬程度的提高,核电厂建筑物结构基础的地震响应有增加的趋势;在周期轴上,基础处的加速度反应谱曲线会随着岩石坚硬程度的提高逐渐向短周期（高频段）方向移动。在高频段,建造于较坚硬岩石上基础结构的加速度反应谱值偏大;在中等频段,建造于较软岩石上基础结构的加速度反应谱值偏大;在低频段,岩石坚硬程度对加速度反应谱的影响不显著。  相似文献   

Variable spatial and temporal weighting schemes for use in multi-phase compositional problems     

《Advances in water resources》1996,19(1):1-27

Variable spatial and temporal weighting of the advective contaminant mole fraction term is explored as a means of reducing numerical dispersion of contaminant plumes in a multi-phase compositional simulator. The spatial schemes considered are upstream, central and a non-linear flux limiter, while fully-implicit and Crank-Nicolson time weighting are examined. The performance of each weighting scheme, in terms of stability of the Newton iteration and computational cost, is assessed for simplified problems designed to be representative of various aspects of more complex subsurface remediation problems. Results indicate that for problems with an homogeneous permeability field, the non-linear flux limited along with fully-implicit weighting gives superior performance to any other combination of spatial and temporal weighting schemes. For heterogeneous permeability fields, the macrodispersion imparted by heterogeneity dominates numerical dispersion so that smearing of contaminant mole fraction fronts does not appear to be a serious problem.  相似文献   

强震作用下核安全级反倾层状软岩高陡边坡组合支挡结构抗震性能研究与加固效果评价     

张卢明  周勇  范刚  蔡红雨  董云 《岩土力学》2020,41(5):1740-1749

比较了不同行业抗震设计规范中边坡地震影响系数和动态放大系数的取值方法,综述国内核电厂高边坡案例的研究进展。以某工程核安全级反倾层状软岩高陡边坡为例,探讨应用多种方法综合分析其在不同地震作用下的动态放大效应、支挡结构抗震性能和加固效果的分析思路。首先,基于典型二维计算剖面,采用拟静力法进行边坡的初步加固设计;然后,基于大型振动台试验和数值计算,研究了不同地震作用下软岩高边坡加速度动力放大效应、支挡结构的抗震性能;最后,通过现场工程监测评价边坡的加固效果。研究结果表明,在强震作用下,核安全边坡按其他行业规范中的抗震参数取值方法进行设计是可行的,通过振动台和数值分析验证边坡整体是稳定的,支挡结构抗震性能良好,该研究思路和方法是合理可行的,并能节约大量工程投资。研究成果可丰富核安全级软岩高陡边坡研究理论与方法,并为核安全级软岩高陡边坡抗震安全评价和工程设计提供技术支持。  相似文献   

激光荧光法测定土壤中铀的不确定度评定     

黄聪  董传江  王力  肖峰  李莉  郑洪龙 《铀矿地质》2020,(1):52-58,72

介绍了激光荧光法测定土壤中总铀含量的不确定度评定方法。建立了不确定度的测量模型,对不确定度来源进行了分析,并对不确定度分量进行量化,计算出环境级土壤样品总铀含量测量的扩展不确定度。结果表明,某0.1 g环境土壤干样总铀含量测量的扩展不确定度为13.04%(k=2),占主导作用的不确定度来源为样品荧光计数测量不确定度。  相似文献   

Calculation of humidity during evaporation from soil     

《Advances in water resources》1999,22(5):495-505

The relative humidity at the surface of a soil is calculated as a function of time from a realistic, exactly solvable model for unsaturated fluid flow.When the evaporation rate is constant, as in the atmosphere-controlled phase, the surface relative humidity suddenly drops at a particular time, even though the humidity–time function is differentiable. This sudden transition still occurs, but is smoother, when more realistic radiation-type boundary conditions are introduced and when the soil-water diffusivity approaches zero continuously at zero water content. In these cases, solutions are obtained by a numerical method of lines which has been validated against the analytically solvable model. A gradual decrease in surface water content is not inconsistent with a sharp, step-like decrease in relative humidity. This is due to the universal exponential Gibbs–Boltzmann relationship between relative humidity and soil-water potential.  相似文献   

Regulatory setting for very large floating platforms in Hawaii     

《Ocean & Coastal Management》2000,43(1):65-85

This paper provides an overview of the regulatory regimes pertinent to operating very large floating platforms (VLFPs) in Hawaii. Coastal and offshore jurisdictions are defined and key county, state and federal authorities and responsibilities are described. Forty applicable state and federal laws are cited. Special consideration is given to marine management areas, state claims for extended jurisdiction, native Hawaiian entitlements, submerged lands, ocean leasing, water quality areas and the humpback whale national marine sanctuary. VLFPs in Hawaii probably will have to be deployed offshore, out of sight of scenic coastal viewplanes, to assure public acceptance. However, offshore positioning is coincident with a simpler regulatory regime (federal) and lowered regulatory uncertainty and risk. The unambiguous delimitation of the seaward extent of state jurisdiction may well be the paramount regulatory issue requiring resolution for deciding where to site a VLFP in Hawaii.  相似文献   

岭澳核电站二期工程基岩爆破安全阈值分析   总被引：2，自引：1，他引：1  

夏祥  李海波  李俊如  朱莅  刘博  王晓炜 《岩土力学》2008,29(11):2945-2951

核电站基础爆破开挖过程中必须严格控制岩体爆破损伤深度,确保建基面安全。以广东岭澳核电站二期工程基础爆破开挖为例,通过现场爆破振动监测、岩体声波试验以及数值模拟,综合分析了岩体爆炸振动衰减规律和损伤特征,研究了距爆源一定距离处岩体振动速度与损伤特征的关系,提出了岭澳核电站二期工程岩体爆炸损伤深度的控制方法,确定了相应的安全阈值。分析结果表明,岭澳核电站二期工程基础爆破开挖时,当距爆源30 m处的岩体质点振动速度不超过5 cm/s时,可保证下卧基岩的损伤深度小于2 m,确保建基岩完整性。  相似文献   

SITE EVALUATION AND VOLCANIC HAZARD ASSESSMENT FOR THE NUCLEAR POWER PLANTS OF CHINA          下载免费PDF全文

XU Jian-dong  YU Hong-mei  ZHOU Ben-gang  CUI Wen-ling  DU Long  WEI Fei-xiang 《地震地质》2019,41(5):1289-1301

Starting from the 1980's of last century, China has launched the national plan of constructing nuclear power plants along the coastline region in eastern China. Currently, in some of these candidate sites, nuclear facilities have been installed and are in operation, but some other nuclear power plants are still under construction or in site evaluation. In 2012 the Atomic Energy Commission issued the specific guide for volcanic hazards in site evaluation for nuclear installations(IAEA Safety Standards Series No. SSG-21), which was prepared under the IAEA's program for safety standards. It supplements and provides recommendations for meeting the requirements for nuclear installations established in the safety requirements publication on site evaluation for nuclear installations in relation to volcanic hazards. To satisfy the safety standards for volcanic hazard, we follow the IAEA SSG-21 guidelines and develop a simple and practical diffusion program in order to evaluate the potential volcanic hazard caused by tephra fallout from the explosive eruptions. In this practice, we carried out a case study of the active volcanoes in north Hainan Province so as to conduct the probabilistic analysis of the potential volcanic hazard in the surrounding region. The Quaternary volcanism in north Hainan Island, so-called Qiongbei volcanic field is characterized by multi periodic activity, in which the most recent eruption is dated at about 4 000a BP. According to IAEA SSG-21, a capable volcano is one for which both 1)a future eruption or related volcanic event is credible; and 2)such an event has the potential to produce phenomena that may affect a site. Therefore, the Qiongbei volcanic field is capable of producing hazardous phenomena that may reach the potential nuclear power plants around. The input parameters for the simulation of tephra fallout from the future eruption of the Qiongbei volcanic field, such as the size, density and shape of the tephra, the bulk volume and column height, the diffusion parameter P(z), wind direction and intensity, were obtained by field investigation and laboratory analysis. We carried out more than 10000 tephra fallout simulations using a statistical dataset of wind profiles which are obtained from China Meteorological Data Sharing Service System(CMDSSS). Tephra fallout hazard probability maps were constructed for tephra thickness threshold of 1cm. Our results show that the tephra produced by the future large-scale explosive eruption from the Qiongbei volcanic field can affect the area in a range about 250km away from the eruption center. In summary, the current key technical parameters related to volcanic activity and potential hazards in IAEA/SSG-21 guidelines, such as 10Ma volcanic life cycle and 1×10^-7 volcanic disaster screening probability threshold, etc. are based on the volcanic activity characteristics in the volcanic island arc system. In consideration of the relatively low level of volcanic activity compared with volcanic island arc system due to the different tectonic background of volcanism in mainland China, the time scale of volcanic disaster assessment in IAEA SSG-21 guideline is relatively high for volcanoes in mainland China. We suggest that the study of "conceptual model" of volcanic activity should be strengthened in future work to prove that there is no credible potential for future eruptions, so that these volcanoes should be screened out at early stage instead of further evaluation by probabilistic model.  相似文献   

潜在影响防城港核电冷源系统的藻类暴发特点及其监测防控技术     

贺立燕  宋秀贤  於凡  王凯  宋书群  俞志明 《海洋与湖沼》2019,50(3):700-706

2014年底,在广西防城港核电厂一期工程1号机组热试期间,核电厂所在的冷源水取水海域钦州湾暴发了球形棕囊藻赤潮,赤潮严重时出现了冷却水系统堵塞现象,严重威胁到核电的安全。本次由藻类引发的威胁核电冷源安全的事件在国内尚属首例,以往人们更多关注核电的温排水对附近海域生物的影响,而反过来,生物对核电正常运行的潜在影响相比之下缺少研究。在此背景下,本文通过研究历史调查资料,对潜在影响防城港核电冷源系统的藻类及其暴发特点进行初步分析,以大规模暴发时易成囊、成团、成簇以堵塞核电冷源入水作为筛选标准,筛选出球形棕囊藻、束毛藻、夜光藻和浒苔几种潜在威胁种,进一步对潜在威胁种的预警监测和防控方法进行初步介绍,以达到早期预防、保障核电冷源系统安全用水的目的,并为其他核电厂提供参考。  相似文献   

核电厂转运-清洗间地震反应分析     

刘旭晨  李小军  王晓辉  陈苏  于跃  沈亮 《震灾防御技术》2022,17(1):124-131

转运-清洗间作为核电厂反应堆堆外换料系统中的主要设施,为反应堆换料操作提供了安全可靠的生物屏蔽空间,转运-清洗间采用的是双钢板重混凝土组合结构。本文基于有限元软件ABAQUS对转运-清洗间的抗震性能进行分析,包括地震动激励下结构的峰值应力、应变和动力特性。结果表明,在转运间的底部悬挑边缘部位存在应力集中,但是钢板、栓钉和重混凝土墙仍有充分的安全裕度。转运-清洗间的整体刚度较大,在设计基准地震动激励下结构反应的峰值加速度放大系数及峰值相对位移较小,结构具有良好的安全性和完整性,核电厂转运-清洗间的设计安全可靠。  相似文献