Seismic response analysis of pipes by a probabilistic approach     

D. Nedjar  M. Hamane  M. Bensafi  S.M. Elachachi  D. Breysse 《Soil Dynamics and Earthquake Engineering》2007,27(2):111-115

Seismic response of buried pipes in longitudinal direction is studied. The effect of the variation of geotechnical properties of the surrounding soil on the stiffness, mass and damping of the soil is considered. The soil–structure interaction depends on pipe stiffness, joint stiffness, the variation of the soil stiffness and the soil mass and damping. Variations of the properties of the surrounding soil along the pipe are described by the random field theory. A numerical model is developed in order to simulate the effects of the variation of the soil on displacements, bending moments in the pipe and also to carry out a statistical analysis. The influence of different parameters regarding design and safety level of the pipe is conducted.  相似文献   

Debris flow susceptibility assessment using a probabilistic approach: A case study in the Longchi area,Sichuan province,China   总被引：3，自引：0，他引：3  

Ming Chang  Chuan Tang  Dan-dan Zhang  Guo-chao Ma 《山地科学学报》2014,11(4):1001-1014

The Longchi area with the city of Dujiangyan, in the Sichuan province of China, is composed of Permian stone and diorites and Triassic sandstones and mudstones intercalated with slates. An abundance of loose co-seismic materials were present on the slopes after the May 12, 2008 Wenchuan earthquake, which in later years served as source material for rainfall-induced debris flows or shallow landslides. A total of 48 debris flows, all triggered by heavy rainfall on 13th August 20l0, are described in this paper. Field investigation, supported by remote sensing image interpretation, was conducted to interpret the co-seismic landslides in the debris flow gullies. Specific characteristics of the study area such as slope, aspect, elevation, channel gradient, lithology, and gully density were selected for the evaluation of debris flow susceptibility. A score was given to all the debris flow gullies based on the probability of debris flow occurrence for the selected factors. In order to get the contribution of the different factors, principal component analyses were applied. A comprehensive score was obtained for the 48 debris flow gullies which enabled us to make a susceptibility map for debris flows with three classes. Twenty-two gullies have a high susceptibility, twenty gullies show a moderate susceptibility and six gullies have a low susceptibility for debris flows.  相似文献   

Study of Statistical Characteristics of wet Season Hourly Rainfall at Hulu Watershed with Γ Function in Qilian Mountains     

Wang Lei  Chen Rensheng  Song Yaoxuan 《地球科学进展》2016,31(8):840-848

The probability distribution of the wet season hourly precipitation is the important basis for the study of the precipitation distribution, especially in mountainous areas. Hulu watershed is the study area located in the upper reaches of Heihe River, Qilian Mountains. By adopting the maximum likelihood estimation, the shape parameter α and scale parameter β of 6 stations were obtained with observed wet season (May to September) half hourly data, and different intensity precipitation probability density distribution, cumulative probability density and probability of precipitation and elevation and precipitation relationship were analyzed. The shape parameter α and scale parameter β is significantly negatively correlated, shape parameter α and average hourly precipitation distribution is consistent. Local topography is also an important factor to affect the precipitation redistribution and the probability distribution of precipitation in Hulu watershed. In addition to the increase of precipitation events, the probability of 1~3 mm mm/h precipitation increases with the altitude, which is the main reason for the increase of precipitation with altitude.  相似文献   

油页岩地质类比资源评价体系的建立     

贾建亮  刘招君  柳蓉  郭巍  陈会军  孙平昌  孟庆涛 《地质学报》2014,88(7):1321-1333

松辽盆地晚白垩纪青山口组和嫩江组蕴藏着丰富的油页岩资源,已查明4处超大型中浅层油页岩矿床,盆地油页岩资源整体呈现"局部查明程度高、整体认识程度低"的特征。本文采用以地质类比法为主、统计算法为辅的统计类比法估算油页岩潜在资源量。在松辽盆地嫩江组探明的超大型矿床——吉林松南油页岩含矿区的类比刻度区内,以松辽盆地油页岩成矿富集条件为理论依据,优选出控制油页岩成矿富集的3个一级和6个派生二级地质因素来建立类比参数库,并提出"多态"定性变换原则处理类比参数。采用特征因子法确定刻度区与预测区的相似类比系数概率分布函数,并构建了油页岩资源体积丰度概率分布函数,从而利用蒙特卡罗法和组合抽样法计算不同置信水平下的油页岩潜在资源量。提出利用"高概率值波动剧烈"选取原则评价概率区间上合理的油页岩潜在资源量,把100%~85%概率区间的资源量作为松辽盆地嫩江组油页岩资源评价的合理值区间。结果显示,松辽盆地嫩江组中浅层油页岩在合理概率下的潜在资源量分别为2867.2×108 t(100%)、3356.2×108 t(95%)、3834.0×108 t(90%)、4307.7×108 t(85%),合理概率区间上的平均资源量为3591.3×108 t。验证分析表明,统计类比法对大范围低勘探程度的预测区资源估算更为准确,填补了中—低勘探盆地油页岩在资源评价方面的不足,可以为其他同类型沉积盆地的能源或矿产资源评价起到借鉴作用。  相似文献   

Probability Prediction Model for Landslide Occurrences in Xi’an,Shaanxi Province,China   总被引：1，自引：0，他引：1  

ZHUANG Jian-qi  IQBAL Javed  PENG Jian-bing  LIU Tie-ming 《山地科学学报》2014,11(2):345-359

Landslides are increasing since the 1980s in Xi’an, Shaanxi Province, China. This is due to the increase of the frequency and intensity of precipitation caused by complex geological structures, the presence of steep landforms, seasonal heavy rainfall, and the intensifcation of human activities. In this study, we propose a landslide prediction model based on the analysis of intraday rainfall （IR） and antecedent effective rainfall （AER）. Primarily, the number of days and degressive index of the antecedent effective rainfall which affected landslide occurrences in the areas around Qin Mountains, Li Mountains and Loess Tableland was established. Secondly, the antecedent effective rainfall and intraday rainfall were calculated from weather data which were used to construct critical thresholds for the 10%, 50% and 90% probabilities for future landslide occurrences in Qin Mountain, Li Mountain and Loess Tableland. Finally, the regions corresponding to different warning levels were identified based on the relationship between precipitation and the threshold, that is; “A” region is safe, “B” region is on watch alert, “C” region is on warning alert and “D” region is on severe warning alert. Using this model, a warning program is proposed which can predict rainfall-induced landslides by means of real-time rain gauge data and real-time geo-hazard alert and disaster response programs. Sixteen rain gauges were installed in the Xi’an region by keeping in accordance with the regional geology and landslide risks. Based on the data from gauges, this model accurately achieves the objectives of conducting real-time monitoring as well as providing early warnings of landslides in the Xi’an region.  相似文献   

Probability distributions for maximum wave and crest heights     

Marc Prevosto  Harald E. Krogstad  Agns Robin 《Coastal Engineering》2000,40(4)

The paper discusses short- and long-term probability models of ocean waves. The Gaussian theory is reviewed, and nonlinear short-term probability distributions are derived from a narrow band second-order model. The nonlinearity has different impact on different measurement techniques, and this is further demonstrated for wave data from the WAVEMOD Crete measurement campaign and laser data from the North Sea. Finally, we give some examples on how the short-term statistics may be used to estimate the probability distributions for the maximum waves during individual storms as well as in a wave climate described by long-term distributions.  相似文献   

利用概率密度分布提取地下流体数字化观测资料中的高频异常信息以2014年鲁甸6.5级地震为例     

王喜龙  贾晓东  王博  王熠熙  王俊  向阳  靳浩  付聪 《地震》2018,38(1):35-48

中国地震地下流体观测经过数字化改造以后, 观测资料的采样频率显著提高。 流体观测资料中的高频数据含有丰富构造信息, 为我们捕捉地震孕育及发生过程中的前兆异常信息提供了有利条件。 但是, 高频信息的出现激发了对数据分析方法改变的需求, 如何研发与数字化高频观测资料相匹配的数据处理和异常识别方法, 从高频观测数据中挖掘潜在的前兆异常信息, 成为目前地震地下研究者首要需解决的关键问题。 应用概率密度分布法对2014年鲁甸6.5级地震前南北地震带174组水位、 水温分钟值高频观测数据进行分析, 结果显示: 鲁甸6.5级地震前共有10个水位测点和7个水温测点出现高频信息异常, 异常多集中在滇西南构造带的滇中次级块体两侧, 且随着时间推移, 有向震中区逼近的变化特征。 通过对震源区及附近地区地壳结构、 构造应力作用及更大范围的区域动力演化特征进行分析, 发现异常信息的空间分布特征与川滇地区地壳运动场具有很好的一致性, 说明概率密度分布可有效反映出区域构造应力作用, 同时也验证了利用概率密度分布在流体观测数据的高频信息异常提取方面具有一定可靠性。  相似文献   

新疆和田台阵PSD与PDF分析   总被引：2，自引：0，他引：2       下载免费PDF全文

杨千里  郝春月  田鑫 《地球物理学报》2019,62(7):2591-2606

和田台阵是我国第一个自主建成并运行至今的小孔径台阵,承担着监测印巴地区核试验以及我国西部地震活动的重要使命.台阵波形数据中充斥着背景噪声,直接影响着数据质量.为了评估台阵噪声水平,本文利用Welch平均周期法对9个子台记录的数十万条噪声样本进行功率谱估计,对出现的谱异常进行了总结归纳,通过绘制概率密度函数图以及单频曲线来研究背景噪声变化范围和规律,最后针对台阵降噪提出了建设性意见.研究结果表明,中心台长周期噪声功率谱密度随季节变化显著,具有周期性;受温度和气压影响,水平分量长周期噪声变化幅度较大,局部频段超出新高噪声模型,建议改善仪器安装条件,或者利用数学方法进行校正.所有子台短周期噪声变化规律与长周期相反,受到采石场影响,谱密度曲线在4~8 Hz之间出现形态规则的高频尖刺,A1、B3、B4子台最为明显,可以通过窄带滤波或者聚束予以压制.本文取得的研究成果为台阵运维提供重要依据,除此之外,总结出的不同地震频谱特征也为地震解释工作提供重要参考.  相似文献   

山东省S波段与C波段天气雷达回波强度的对比分析     

刘雨佳  陈洪滨  朱君鉴 《气象科学》2014,34(1):87-95

山东省济南市的S波段天气雷达与泰山山顶处的C波段雷达相距67 km。为了定量分析两部雷达扫描观测的回波强度在不同个例中的差异程度,从2007—2010年两部雷达观测中选出10次有明显回波的个例,对3个高度的CAPPI及相同观测区域的格点化回波强度资料进行对比分析。结果表明:10次个例的整体对比中,两部雷达在3个高度(2、3、4 km)的CAPPI回波强度资料的概率密度有较好的相似性;两部雷达回波强度均值随着选取高度增加而增大,每个高度上S波段均值较C波段大2 dBz左右。其中,6次降雨个例3 km的CAPPI资料对比中,一次平均强度小于30 dBz的降水过程,且强回波所占比例较小,C波段雷达衰减小,两部雷达测量回波强度一致性最好;其余5次过程中,S波段雷达测量的平均回波强度值均在30 dBz以上,且强回波所占比例较多,C波段由于衰减等原因,两部雷达的测量存在不同程度的差异。  相似文献   

贵州省降雨型滑坡预报模型及检验          下载免费PDF全文

李忠燕  田其博  左晋  罗阳欢  曹蔚 《沙漠与绿洲气象(新疆气象)》2022,16(3):47-53

本文利用贵州省2010—2017年630次降雨型滑坡资料以及国家气象台站和区域自动气象站逐小时降水资料，分析了贵州省降雨型滑坡的时空分布特征。基于5个不同时效降水指标与滑坡累积发生概率的拟合曲线公式，得到不同概率对应的5个降水指标的降水阈值，建立贵州省降雨型滑坡预报模型,并利用2018年新增滑坡样本对预报模型进行检验。结果表明：贵州省降雨型滑坡高发期主要集中在5—7月，其中6月滑坡发生概率最高，约48.6 %；7月次之，约34.9 %。当R1h、R3h、R6h、R24h、R3d分别大于等于26.9 mm、48.9 mm、62.9 mm、79.5 mm、92.0 mm时，发布滑坡预报预警。在降雨型滑坡预报模型中，随着5个不同时效指标的降水量增大，降雨型滑坡累积发生概率变化呈现前后增加缓慢，中间快速增加的变化特征。模型检验结果表明贵州省降雨型滑坡预报模型有一定的准确性，且5个降水指标均具有一定的实用性，其中利用R3d开展降雨型滑坡预报准确率最好。  相似文献