共查询到19条相似文献,搜索用时 65 毫秒
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近年来,伴随着极端气候的不断出现,强降雨引发的地质灾害逐渐增多。大气降雨的入渗一方面改变了岩土体的物理力学性质,另一方面,随着降雨的进一步进行和包气带内土中所含水分进一步下渗,大气降雨将补给在相对隔水的滑带处形成的潜水面。论文从渗流基本原理出发,采用稳定渗流情况下的潜水面作为非稳定渗流的初始值,推导出降雨入渗下潜水面的解析解,然后对近似解析解的误差做定量分析,阐述近似解析解在滑坡等地质灾害的潜水位求解过程中的适用性,可用于指导受大气降雨补给潜水面的滑坡浸润线的求解,便于分析大气降雨产生的直接影响。 相似文献
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环境同位素技术在区域地下水资源补给及可更新性中的应用 总被引:3,自引:0,他引:3
应用环境同位素D、18O、T、14C,从可持续发展的角度初步探讨了鄂尔多斯盆地地下水资源的形成演化规律及可更新程度,为可持续性开发利用区域地下水资源提供了系统科学支持的理论基础。 相似文献
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根据红砂岩碎(块)石具有吸水崩解特性和不均匀性,对强夯加固处理红砂岩碎(块)石填土地基的检验方法进行了探讨。采用室内试验、浅层平板载荷试验、重型圆锥动力触探试验并与波速试验相互验证。经对比分析得出:若强夯前对红砂岩碎(块)石填土进行相关处理,降雨对夯后填土的影响深度较浅,其硬壳层既是良好持力层又是隔水层,它使地基内红砂岩的残余水活性无法发挥,从而使夯后地基沉降减少。采用上述综合方法检验的小区经过两年的运营,一切正常。说明上述综合检验方法是可行的,真实的反映了强夯施工质量,可供类似工程参考。 相似文献
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探讨了箱基和上部结构-框架共同作用的机理,并对现行计算方法提出个人意见和初步建议。为了箱基的防渗漏,笔者提出一个大胆的设想。此外在文中还给出用杆件力学方法计算框架-箱基-地基的共同作用。 相似文献
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高建民 《建筑砌块与砌块建筑》2012,(5):49-56
1 范围本文件规定了生态型多孔混凝土的抗压强度、抗折强度、劈裂抗拉强度、密度、连续孔隙率、透水系数、收缩性、抗冻性的试件制作和试验方法.本文件适用于具有明显透水性的、多孔的现浇多孔混凝土和预制多孔混凝土制品的性能评价.2规范性引用文件下列文件对于本文件的应用是必不可少的.凡是注日期的引用文件,仅注日期的版本适用于本文件.凡是不注日期的引用文件,其最新版本(包括所有的修改单)适用于本文件. 相似文献
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小样本流域降雨强度公式和设计降雨分布的推求方法 总被引:1,自引:0,他引:1
以挪威中部瑞斯沃伦(RISVOLLAN)流域1991年-2000年的降雨观测资料为基础,采用中国国家标准(GBJ 14-87)推荐的适用于观测期较短、观测雨量数据较少的年多次取样方法,在进行经验和理论频率分析的基础上,确定了设计降雨的重现期(T)及其对应的频率(P)、降雨强度(i)和降雨历时(t)的关系(即P-i-t曲线),以及降雨强度公式和设计降雨分布,从而为该流域现有管网的排水能力校核提供了参考依据. 相似文献
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以重庆市海绵城市建设试点区域秀山县为研究对象,通过实时监测传统片区和低影响开发(LID)片区的降雨径流数据,探析LID片区在不同降雨强度下对径流量的削减效果。结果表明,经LID改造后,地面透水性增大,所容纳的雨水量增加,与传统开发模式相比,中雨条件下对径流总量和峰值的削减率分别可达到80. 4%和56. 0%; LID措施的蓄水容积有限,不同降雨条件下对径流总量和峰值的削减程度不同,削减程度排序为:中雨(80. 4%、56. 0%)>大雨(69. 4%、64. 4%)>暴雨(56. 1%、60. 8%),而且随着降雨等级的增大,LID片区的径流产生时间和峰现时间的滞后效果减弱,在暴雨条件下与传统片区无明显差别; LID片区是否产生径流以及产生多大的径流,主要由降雨强度决定,而与降雨量关系不大,在本研究中,当降雨强度> 0. 2 mm/min时才会产生径流,且降雨强度越大,径流量就越大。 相似文献
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A. P. García‐Marín J. L. Ayuso‐Muñoz E. V. Taguas‐Ruiz J. Estevez 《Water and Environment Journal》2011,25(4):522-531
The flood and drought cycles suffered of old by the province of Malaga, the variability in the distribution of rainfall throughout the province and the reduced length of the data series make it of interest to carry out a regional analysis (RA) of the yearly maximum daily precipitation data to obtain appropriate rainfall quantiles. By taking these maximum precipitations values from 72 weather stations, and their physiographic parameters latitude and altitude, four regions with similar rainfall patterns have been determined by the principal component analysis statistical technique. Then, carrying out an RA of the yearly maximum daily precipitations for each of the regions discriminated, it was observed that three of them were homogeneous for the parameter being studied. In those homogeneous regions that grouped data of different stations but close rainfall pattern, frequency curves could be calculated for several return periods by means of the functions that best fit the data of each region. With these regional curves, it has been possible to obtain more accurate values of the maximum daily quantiles for each of the stations analysed than through the conventional local frequency analysis. 相似文献
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Biodegradation of N-Nitrosodimethylamine (NDMA) has been found through laboratory incubation in unsaturated and saturated soil samples under both aerobic and anaerobic conditions. However, direct field evidence of in situ biodegradation in groundwater is very limited. This research aimed to evaluate biodegradation of NDMA in a large-scale groundwater system receiving recycled water as incidental and active recharge. NDMA concentrations in 32 monitoring and production wells with different screen intervals were monitored over a period of seven years. Groundwater monitoring was used to characterize changes in the magnitude and extent of NDMA in groundwater in response to seasonal hydrogeologic conditions and, more importantly, to significant concentration variations in effluent from water reclamation plants (associated with treatment-process changes). Extensive monitoring of NDMA concentrations and flow rates at effluent discharge locations and surface-water stations was also conducted to reasonably estimate mass loading through unlined river reaches to underlying groundwater. Monitoring results indicate that significant biodegradation of NDMA occurred in groundwater, accounting for an estimated 90% mass reduction over the seven-year monitoring period. In addition, a discrete effluent-discharge and groundwater-extraction event was extensively monitored in a well-characterized, localized groundwater subsystem for 626 days. Analysis of the associated NDMA fate and transport in the subsystem indicated that an estimated 80% of the recharged mass was biodegraded. The observed field evidence of NDMA biodegradation is supported by groundwater transport modeling accounting for various dilution mechanisms and first-order decay for biodegradation, and by a previous laboratory study on soil samples collected from the study site [Bradley, P.M., Carr, S.A., Baird, R.B., Chapelle, F.H., 2005. Biodegradation of N-Nitrosodimethylamine in soil from a water reclamation facility. Bioremediat. J. 9 (2), 115-120.]. 相似文献
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This study evaluated the removal of natural organic matter (NOM) and structural changes in the microbial community during infiltration of humic lake water at three artificial groundwater recharge (AGR) sites in Finland. The three sites were at waterworks in H?meenlinna, Jyv?skyl? and Tuusula, sites A, B and C, respectively. Site A used groundwater recharge by both basin and sprinkling infiltration, site B used only sprinkling infiltration, and site C used only basin infiltration. Reductions of total organic carbon at sites A, B and C were 91%, 84% and 74%, respectively, in the winter, and 88%, 77% and 73%, respectively, in the summer. The Finnish national recommended value of 2 mg/l for TOC was achieved at all sites and the TOC of natural groundwater at site C was much lower, at 0.6 mg/l. Large molecular fractions of NOM were removed more efficiently than the smaller ones. Total amount of DAPI-stained cells decreased during infiltration at sites A, B and C in winter by 94%, 94% and 75% and in summer by 96%, 97% and 94%, respectively. Bacterial communities in raw waters and extracted groundwaters were diverse with changes occurring during infiltration, which was shown by DNA extraction followed by PCR of 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE) fingerprinting. While the natural groundwater microbial community was diverse, it was different from that of the extracted groundwater in the AGR area. Simultaneous organic carbon removal and the decrease of bacterial counts during infiltration indicated biodegradation. In addition, the changing DGGE profiles during the process of infiltration, demonstrated that changing environmental conditions were reflected by changes in bacterial community composition. 相似文献
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B. Asgarian R. M. Nojoumi P. Alanjari 《The Structural Design of Tall and Special Buildings》2014,23(2):81-93
Performance assessment of high‐rise buildings has attracted peculiar attention among engineers. Care should be taken once higher‐mode effects are to be incorporated into analyses and designs. Recently, performance‐based evaluations have been widely used by designers to meet the required target capacities of engineering projects. A common tool to perform such studies is incremental dynamic analysis (IDA), which has been utilized for first‐mode‐dominant ordinary structures, whereas taller buildings demand other considerations to be made so that a thorough assessment of the structural response can be achieved. In this paper, performance‐based studies have been carried out for a sample 30‐story tall building, which takes advantage of tubular frame as lateral‐load‐resisting system. IDA is performed subsequently to quantify the structural response against a wide‐range of seismic loadings. Advanced intensity measures (IMs) are applied to optimize the capacity assessments resulting from multitude of non‐linear time‐history analyses. Finally, performance‐based evaluations have been carried out to provide a thorough assessment of target capacities that are normally advised by widely accepted codes. Results are also compared with regular short buildings where higher‐mode effects do not contribute significantly to structural response. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Noor Al Khathlan Zainab Al-dabbus Noor Al-khdir Maryam Al-Matar Sajedah Al-Nusaif Bashayer Al Yami 《Indoor air》2021,31(5):1577-1582
Burning incense (bakhour) is a common cultural practice in Saudi Arabia. However, its health risk assessment has rarely been studied. This study aims to investigate the association between exposure to incense smoke on lung function impairments and respiratory symptoms among young adults in Saudi Arabia. A community-based cross-sectional study was designed with a representative study sample (N = 125) in the Eastern Province of Saudi Arabia. Study participants, exposed group (n = 45), working in bakhour shop and matched control (n = 80), no history of occupational exposure to bakhour smoke, were recruited randomly from the population registry. Socio-demographic and respiratory symptom information were collected through a questionnaire developed based on European Community Respiratory Health Survey II (ECRHS II). Lung function measurements were conducted using a field spirometer. The overall prevalence of wheezing or whistling was 16.8%, with a higher prevalence in exposed group 35.5%. In adjusted models, exposed to incense smoke remained positively associated with respiratory symptoms: wheezing or whistling; breathlessness; chest tightness shortness of breath; woken up by an attack of coughing. Our study suggests that inhaled incense smoke in occupation or at home is a risk factor of lung function impairments among adult population in Saudi Arabia. 相似文献