三峡机场高填方土基沉降观测与计算研究   总被引：2，自引：1，他引：2  

姚成焕  石宜生 《岩土力学》2001,22(4):513-518

运用工程测量与土力学计算相结合的方法并考虑飞机荷重的影响，将各种方法的计算结果进行综合分析，合理地拟定了三峡机场高填方土基剩余沉降量、倾斜、土基固结度和回弹模量等技术值，为高填方土基面上混凝土施工期决策及时地提供了科学依据，据此而进行的施工，经竣工验收和4年来的通航检验，证明土基稳定，运行安全。  相似文献   

Laboratory depositional and compaction-caused inclination errors carried by haematite and their implications in identifying inclination error of natural remanence in red beds     

Xiaodong Tan  Kenneth P. Kodama  Dajun Fang 《Geophysical Journal International》2002,151(2):475-486

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倾斜荷载作用下层状非均质地基的极限承载力   总被引：1，自引：0，他引：1  

袁凡凡  栾茂田  闫澍旺  林源 《岩土力学》2004,25(Z2):564-567

通过一定的室内模型试验对倾斜荷载作用下层状非均匀地基的极限承载力进行了试验研究.引入荷载倾斜影响系数,对于层状非均质地基的极限承载力计算公式进行了修正,给出了倾斜荷载作用下的地基极限承载力计算公式.根据模型试验结果,对所建立的计算公式进行验证.结果表明,对于倾斜荷载作用下的层状非均匀地基,根据修正后的Meyerhof承载力公式所得到的计算结果能够较好地与试验结果吻合.  相似文献   

Shallow bias in Mediterranean paleomagnetic directions caused by inclination error     

Wout Krijgsman  Lisa Tauxe 《Earth and Planetary Science Letters》2004,222(2):685-695

A variety of paleomagnetic data from the Mediterranean region show a strong bias toward shallow inclinations. This pattern of shallow inclinations has been interpreted to be the result of (1) major northward terrane displacement, (2) large nondipole components in the Earth's magnetic field, and (3) systematic inclination flattening of the paleomagnetic directions. Here, we use the observation that, in addition to the well-known variation of magnetic inclination with latitude, the N-S elongation of directional dispersion also varies, being most elongate at the equator and nearly symmetric at the poles. Assuming that inclination shallowing follows the relationship long known from experiment, we invert the inclinations using a range of “flattening factors” to find the elongation/inclination pair consistent with a statistical model for the paleosecular variation. We apply the so-called “elongation/inclination” method to the extensive paleomagnetic data sets from the Miocene sediments of the Calatayud basin (Spain) and the island of Crete (Greece). After correction, the Spanish data are in good agreement with the expected middle Miocene latitude of the region. The data from Crete suggest that it occupied a position in the late Miocene about 275 km north of the predicted location. This is in agreement with the geological and geodynamical models for the east Mediterranean region, which indicate that slab rollback processes in combination with Anatolian push generated southward migration of Crete. The 7.5 million year average displacement rate of Crete estimated by the E/I method is 37 mm/yr to the south, which closely coincides with present-day rates based on global positioning system (GPS) and model measurements. We also show that inappropriate tilt corrections lead to a shallow inclination bias as well, explaining that observed in studies of lava flows of the region. We conclude that the east Mediterranean inclination anomaly is caused by sedimentary inclination error and not by a persistent octupolar contribution to the geomagnetic field, or northward transport.  相似文献   

CTM—DI磁通门经纬仪观测操作方法   总被引：2，自引：0，他引：2  

王娜于春颂  王艳荣薛志芳  郭建芳李非 张墨思 《地震地磁观测与研究》2006,27(B08):58-63

CTM—DI磁通门经纬仪是一种性能优良的国产地磁测量仪器，使用方便，精度较高，对于相对记录数字化后基线值的确定具有不可或缺的重要作用，在观测实践中理论联系实际，对磁通门经纬仪观测操作方法进行研究总结。  相似文献   

Remanence magnetic records of the recent 130 000 years from the sediments in Nansha area, South China Sea     

Yang Xiaoqing  Zhou Wenjuan  Gao Fanglei  Li Huamei 《Frontiers of Earth Science》2007,1(1):80-87

Two hundred and eighty-one samples, collected from drilling core NS93-5 located in the Nansha area of the South China Sea, were used to study the magnetic characteristics of the sediments in the sea. Detailed rock magnetic results show that the magnetic minerals of the sediments were dominated by ferrimagnetic minerals such as magnetite, and a small contribution of hematite and maghematite also existed. The sediments recorded three negative values of remanence magnetic inclination at the depth: 191–206 cm, 232–248 cm, and 292–308 cm. The corresponding ages of these negative values were 65.87–68.7 ka B.P., 73.4–80.8 ka B.P. and 108.4–113.6 ka B.P., respectively, according to stratigraphy of oxygen isotope, ¹⁴C, and the age of a volcanic ash layer. The negative value during 108.4–113.6 ka B.P. may be the record of a Blake event in the sediments of the Nansha area. Translated from Marine Geology & Quaternary Geology, 2006, 26(1): 59–66 [译自: 海洋地质与第四纪地质]  相似文献   

等熵面和湿等熵面倾斜发展的诊断分析   总被引：3，自引：0，他引：3  

冉令坤  楚艳丽 《大气科学》2007,31(4):655-665

利用等压坐标系中的热力学方程和水汽方程推导出可以诊断分析等熵面（等位温面）和湿等熵面（等相当位温面） 倾斜变化的倾角方程。等熵面倾角的局地变化由倾角平流输送项、风速切变项和非绝热加热项共同决定，而影响湿等熵面倾角局地变化的强迫项除倾角平流输送项、风速切变项和非绝热加热项之外，还包括垂直热量通量切变项。NCEP/NCAR实时分析资料的分析结果表明，大气斜压性、相对垂直涡度与等熵面和湿等熵面的倾角密切相关，它们的正高值区互相重叠；垂直风速切变项，特别是垂直速度的经向切变项是影响等熵面倾斜发展的主要强迫项，而纬向和经向风速的垂直切变项对湿等熵面倾角演变的贡献最大。  相似文献   

各向异性岩石钻进用钻头和孔底装置的分析研究与探讨          下载免费PDF全文

汤凤林  宁伏龙  段隆臣 《探矿工程》2021,48(2):54-63

钻探工程中可以遇到各种岩石。按物理力学性质来说,岩石可是均质（各向同性）和非均质（各向异性）的。多数情况下,在深孔钻进时,岩石可能受地质条件的影响,是各向异性的。各向异性岩石的特点之一是,不同受力方向上的强度不同,因此钻孔容易弯曲,直接影响钻探效率和质量。俄罗斯科研人员对各向异性岩石中钻进时使用的钻头和孔底装置进行了大量研究,取得了较好的效果,值得我们参考。  相似文献   

激光雷达和点云切片算法结合的森林有效叶面积指数估算   总被引：2，自引：0，他引：2  

路璐  郑光  马利霞 《遥感学报》2018,22(3):432-449

叶面积指数(LAI)是定量模拟和刻画植被冠层结构、生理过程以及研究森林生态系统碳水循环中物质和能量交换的重要生物物理参数之一。定量分析林冠元素的3维空间分布是准确估算森林叶面积指数的重要基础和关键步骤。本文利用地面激光雷达扫描系统(TLS),获取了不同树种、密度、年龄和空间分布的森林3维点云数据,利用"径向半球点云切片"和"点云法向量重建"算法分别计算森林的角度孔隙率和消光系数,进而得到森林冠层的有效叶面积指数。通过与利用传统光学仪器得到的结果比较发现:单站半球式激光雷达扫描得到森林样方尺度的结果与LAI-2200和数字半球摄影观测所得结果的相关性分别为R2=0.7084(N=9,p0.01)和0.7409(N=14,p0.01)。通过角度分辨率(LBA)和角度孔隙率(AGF)的敏感性分析,建议径向半球切片算法的角度分辨率应参考中心单站TLS半球式扫描所设置的采样间距。本文所采用的径向半球切片算法可以有效地利用单站半球式扫描所获取的3维点云进行森林冠层有效叶面积指数的定量估算。  相似文献   

Tectonic implications of paleomagnetic data from upper Cretaceous sediments in the Oyubari area, central Hokkaido, Japan     

Machiko  Tamaki  Yasuto  Itoh 《Island Arc》2008,17(2):270-284

Abstract   Paleomagnetic studies provide constraints on the geometric configuration of the eastern Eurasian margin on geological time scales. Characteristic remanent magnetization components were isolated from eight sites by progressive demagnetization executed on samples from 25 sites in the Oyubari area, central Hokkaido where the Late Cretaceous Yezo Group is distributed. After tilt-correction, all sites show normal polarity site-mean directions, and well-clustered directions pass a positive fold test and a correlation test. Planktonic foraminifera indicate an age range of Cenomanian to Turonian, and the studied section is correlated to the geomagnetic polarity chron C34n. Reliable formation-mean directions that have been corrected for post-depositional shallowing (D = 7.5°, I = 65.9°, α₉₅ = 6.6°) are characterized by inclination data indicative of no significant latitudinal translation since the Late Cretaceous. Central Hokkaido has, therefore, been situated adjacent to easternmost Mongolia including Sikhote Alin around the present latitude since the Late Cretaceous. Declination data require significant differential rotation between Hokkaido and the eastern Asian margin, which may be indicative of rearrangement of crustal blocks along the continental margin.  相似文献