排序方式： 共有45条查询结果，搜索用时 62 毫秒
1.
Journal of Geographical Sciences - Since 2007, the Chinese government has initiated the building of national eco-cultural protection areas (NECPAs), thereby embarking on a significant... 相似文献
2.
For slope condition of ground surface, the asymmetrical deformation about the vertical center line and the horizontal center line of the tunnel cross section can be formed. A unified displacement function expressed by the Fourier series is presented to express the asymmetrical deformation of the tunnel cross section. Five basic deformation modes corresponding to the expansion order 2 are a complete deformation mode to reflect deformation behaviors of the tunnel cross section under slope boundary. Such this complete displacement mode is implemented into the complex variable solution for analytically predicting tunneling-induced ground deformation under slope boundary. All of these analytical solutions are verified by good agreements of the comparison between the analytical solutions and finite element method results. A parameter study is carried out to investigate the influence of deformation modes of the tunnel cross section, geometrical conditions of the tunnel and the slope angle, and “Buoyancy effect” on the displacement field. Finally, the proposed method is consistent with measured data of the Hejie tunnel in China qualitatively. The presented solution can provide a simplified indication for evaluating the ground deformation under slope condition of ground surface. 相似文献
3.
Liquefaction macrophenomena in the great Wenchuan earthquake 总被引：3，自引：2，他引：1
Longwei Chen Xiaoming Yuan Zhenzhong Cao Longqing Hou Rui Sun Lin Dong Weiming Wang Fanchao Meng Hongjuan Chen 《地震工程与工程振动(英文版)》2009,8(2):219-229
On May 12, 2008 at 14:28, a catastrophic magnitude M 8.0 earthquake struck the Sichuan Province of China.The epicenter was located at Wenchuan (31.00°N, 103.40°E). Liquefaction macrophenomena and corresponding destruction was observed throughout a vast area of 500 km long and 200 km wide following the earthquake. This paper illustrates the geographic distribution of the liquefaction and the relationship between liquefaction behavior and seismic intensity, and summarizes the liquefaction macrophenomena, including sandboils and waterspouts, ground subsidence, ground fissures etc., and relevant liquefaction features. A brief summary of the structural damage caused by liquefaction is presented and discussed. Based on comparisons with liquefaction phenomena observed in the 1976 Tangshan and 1975 Haicheng earthquakes, preliminary analyses were performed, which revealed some new features of liquefaction behavior and associated issues arising from this event. The site investigation indicated that the spatial non-uniformity of liquefaction distribution was obvious and most of the liquefied sites were located in regions of seismic intensity Ⅷ. However, liquefaction phenomena at ten different sites in regions of seismic intensity Ⅵ were also observed for the first time in China mainland. Sandboils and waterspouts ranged from centimeters to tens of meters, with most between 1 m to 3 m. Dramatically high water/sand ejections,e.g., more than 10 m, were observed at four different sites. The sand ejections included silty sand, fine sand, medium sand,course sand and gravel, but the ejected sand amount was less than that in the 1976 Tangshan earthquake. Possible liquefaction of natural gravel soils was observed for the first time in China mainland. 相似文献
4.
福建光泽地区是闽北地区重要的萤石矿成矿远景区,具有寻找隐伏—半隐伏萤石矿的潜力,但是目前该区隐伏—半隐伏萤石矿找矿成果较少。通过对福建光泽地区I号萤石矿预测区开展物化探综合信息找矿方法应用,探讨物化探综合信息找矿方法在隐伏—半隐伏萤石矿找矿中的应用效果。结果表明: 区域水系沉积物测量和大比例尺化探剖面测量圈出的F、Ca等综合异常信息可协助筛选、确定萤石矿找矿目标区; 将高精度磁法测量与视电阻率联合剖面测量相结合,可进一步判断萤石矿控矿构造的位置和规模; 高密度电阻率法测量可协助确定控矿构造的深部延伸情况。地表检查和深部钻探验证表明: 区域化探、高精度磁法测量、视电阻率联合剖面测量和高密度电阻率法测量等物化探综合信息找矿方法组合,可指导隐伏—半隐伏萤石矿的找矿工作。 相似文献
5.
MENG Fanchao CUI Yan CAO Yingchang QIU Longwei WEI Jiayi QU Zhijing LIU Jiaqi 《《地质学报》英文版》2017,91(4):1495-1496
<正>Objective The North China Craton(NCC)is one of the oldest continental fragments,which underwent multistage crust growth during the early Precambrian from3.8 Ga to 1.8Ga.In previous studies,many zircon ages have been obtained from the exposed basement rocks.However,we know little about the hidden basement because of Phanerozoic to Cenozoic strata coverage.The drill holes provided a rare opportunity to obtain the basement rocks beneath the Bohai Bay Basin(BBB).In this study,we 相似文献
6.
利用国内外287次5级以上的实际地震记录,研究了地震动有效幅值的不对称性特征及其规律。分别用有效幅值不对称比和有效幅值作用次数不对称比来描述地震动的不对称性,统计结果具有规律性,并提出了其估计公式。结果表明:地震动有效幅值不对称性和有效幅值作用次数不对称性特征明显,幅值不对称比的平均值不受震级影响,但与截断比呈非线性递增关系,截断比小于1/3时不对称比在1.07～1.20之间,截断比大于1/3时不对称比在1.13～1.96之间;有效幅值作用次数不对称比的平均值不受震级影响,但与截断比呈非线性递增关系,截断比小于1/3时作用次数不对称比在1.04～1.31之间变化,截断比大于1/3时作用次数不对称比在1.22～1.80之间。 相似文献
7.
8.
简要介绍了单基站CORS定位技术原理以及CORS的基本算法和发布方式。比较了单基站CORS和常规RTK定位技术,体现了CORS系统的优势。着重介绍了使用单基站CORS放样的具体步骤,包括点位放样、直线放样和曲线放样。为今后工程提供参考。 相似文献
9.
非洲乍得盆地玄武岩K-Ar和39Ar-40Ar年代学及其动力学背景 总被引：1，自引：0，他引：1
乍得的Doba、Bongor和Lake Chad盆地是早白垩世中非右行走滑应力场控制下形成的一系列中新生代陆内拉分盆地,形成与中、赤道及南大西洋打开有关。钻井揭示了盆地内分布有大量的中新生代玄武岩。系统的K-Ar、Ar-Ar法年代学研究发现,至少可识别出2个周期的火山活动旋回,即（1）95-75Ma,只分布于Doba盆地;（2）66-52Ma,分布于Bongor和Lake Chad盆地。研究表明,乍得盆地内中新生代火山活动是板内伸展应力机制下的产物,与白垩纪整个西中非地区的区域构造背景相一致,岩浆作用与裂谷作用密切相关。 相似文献
10.
Meng Fanchao Li Mingcai Cao Jingfu Li Ji Xiong Mingming Feng Xiaomei Ren Guoyu 《Theoretical and Applied Climatology》2018,133(1-2):521-530
Theoretical and Applied Climatology - Climate plays an important role in heating energy consumption owing to the direct relationship between space heating and changes in meteorological conditions.... 相似文献