南水北调中线工程不同调水规模对汉江中下游影响分析   总被引：18，自引：2，他引：16  

沈大军 《地理学报》1998,53(4):341-348

南水北调中线工程是解决我国北方地区水资源紧缺的重大战略措施。但调水将给汉江中下游的水文情势及用水带来一定的影响。文章分析了丹江口水库不同调水方案对汉江中下游水位、流量及灌溉和航运的影响,并提出补偿工程措施。调水６０×１０８ｍ３对汉江中下游的影响较小,可基本不予补偿;调水１５０×１０８ｍ３的影响稍重,但对航运和灌溉用水的影响不大,适当补偿可以解决;调水２３０×１０８ｍ３对汉江中下游水位流量及用水的影响十分严重,必须全部渠化并修建江汉运河。  相似文献   

松花江水下爆破孔施工技术          下载免费PDF全文

赵大军  徐龙献  陈宝义 《探矿工程》1998,(4):12-14

在东北严寒季节,在松花江上施工水下爆破孔。介绍了施工设备及施工平台,根据不同地层分别采用静压振动下套管护壁及潜孔锤钻进方法,设计了风路系统,改进了套管妆方法,并采取了科学的管理方法,取产好的效果。  相似文献   

城市地下空间管理实景化     

李大军  王明洋 《地理空间信息》2009,7(3):121-123

阐述了城市地下空间管理的重要性，提出了一种新型的地下空间管理方法——基于实景可量测地图的地下空间管理，用于提高城市地下空间资源管理和应急管理水平，  相似文献   

结构信息约束的三角网格模型简化方法     

李大军  苟国华  吴天辰  黄九松  惠振阳 《测绘科学》2021,46(8):88-95,164

针对经典的二次误差度量边塌陷网简化算法存在的模型边缘缺损、三角面形状和拓扑异常等问题,该文在此基础上改进算法,提出一种基于结构信息约束的网简化方法.算法考虑三角面的形状和法向在边塌陷前后的变化,将这些结构变化信息量化与二次误差度量组成复合塌陷代价值;同时给出一种三角面间压覆检测方法,将检测结果作为边塌陷决定条件之一,以此来保护三角面的形状和三角网的流形拓扑结构;此外,通过重新定义边界点的二次误差矩阵,自适应地提升边界点所在边的塌陷阈值,从而实现在简化过程中对模型边缘的保护.实验结果表明,该文方法得到的简化三角网边缘完整,算法鲁棒地维护最佳三角面形状和流形拓扑结构,有效地改善了重建三维模型的效果.  相似文献   

Impact of impoundment on groundwater seepage in the Three Gorges Dam in China based on CFCs and stable isotopes     

Lei Zhang  Duoxing Yang  Yaowei Liu  Yongtai Che  Dajun Qin 《Environmental Earth Sciences》2014,72(11):4491-4500

It is a common concern that the groundwater flow field caused by the Three Gorges Dam changes the regional seismic activity and environment. The changes in the seepage region could be effectively reflected through the analysis of the groundwater age using chlorofluorocarbons (CFC)-based techniques. In this study, the influences of the reservoir water on groundwater and the seepage region boundary of the reservoir were investigated using CFCs, stable isotopes, and water level in groundwater, reservoir water, and spring water during the water storage process of the Three Gorges Reservoir. The results show that the water supplied by the groundwater is older, whereas the water supplied by the reservoir and the springs is younger. With an increase in the water level of the reservoir, the water in well W3, which is located at the vice dam of the head region, becomes older due to the reservoir loading effect, whereas the water in well W4 become younger due to the lateral seepage of reservoir water. This finding indicates that the groundwater seepage regions in wells W3 and W4, which are located at upstream of the reservoir, are all influenced by the Three Gorges Reservoir. In contrast, the sampling points in the northern section of the Xiannvshan fault zone, which is farther from the dam, did not exhibit any direct hydraulic connection between the groundwater and the reservoir water; thus, the reservoir seepage effects may not affect the northern part of the Xiannvshan fault zone. These research results provide important reference data that can be used to analyze the effects of the Three Gorges reservoir storage on the regional environment.  相似文献   

Fine-scale volume heterogeneity measurements in sand     

Dajun Tang Briggs  K.B. Williams  K.L. Jackson  D.R. Thorsos  E.I. Percival  D.B. 《Oceanic Engineering, IEEE Journal of》2002,27(3):546-560

As part of the effort to characterize the acoustic environment during the high frequency sediment acoustics experiment (SAX99), fine-scale variability of sediment density was measured by an in situ technique and by core analysis. The in situ measurement was accomplished by a newly developed instrument that measures sediment conductivity. The conductivity measurements were conducted on a three-dimensional (3-D) grid, hence providing a set of data suited for assessing sediment spatial variability. A 3-D sediment porosity matrix is obtained from the conductivity data through an empirical relationship (Archie's Law). From the porosity matrix, sediment bulk density is estimated from known average grain density. A number of cores were taken at the SAX99 site, and density variations were measured using laboratory techniques. The power spectra were estimated from both techniques and were found to be appropriately fit by a power-law. The exponents of the horizontal one-dimensional (1-D) power-law spectra have a depth-dependence and range from 1.72 to 2.41. The vertical 1-D spectra have the same form, but with an exponent of 2.2. It was found that most of the density variability is within the top 5 mm of the sediment, which suggests that sediment volume variability will not have major impact on acoustic scattering when the sound frequency is below 100 kHz. At higher frequencies, however, sediment volume variability is likely to play an important role in sound scattering.  相似文献   

基于机器学习的水平孔绳索取心钻进钻压预测模型     

高希坤  赵大军  陈勇 《地质论评》2023,69(Z1):559-560

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Research on formation density MWD instrument in engineering geological exploration     

Dajun ZHAO  Guosheng JIANG  Youhong SUN  Junhua ZHENG  Zhuwen WANG 《世界地质(英文版)》2008,11(4)

A high efficiency method is very important in geological survey for a new city in China. Geophysical parameters are Measured While Drilling(MWD), and these parameters are processed and explained on the ground, so the method can replace conventional engineering geological exploration for drilling rock sample. According petroleum engineering MWD, using the different characters of different rock absorbs γ radial, with the method of storing data in hole and explaining data on the ground, engineering geological exploration formation density MWD is researched. The MWD works stabilized, and the performance is good with precise data.  相似文献   

超声波振动下不同应力条件对岩石强度影响的试验     

尹崧宇  赵大军 《吉林大学学报(地球科学版)》2019,49(3):755-761

振动有助于碎岩,以往关于振动碎岩机理的研究大多在低频率段展开。为填补超高频率段下振动碎岩机理的空白,采用单轴动静组合加载模式,开展了超声波振动下不同应力条件对岩石强度影响的试验研究,其中超声波振动频率为20kHz,预压范围为100～500N。研究结果表明:当预压小于200N时,岩石内部应力状态无法满足强度准则,岩石强度下降不明显;当预压大于等于200N时,岩石强度随振动时间的增加而逐渐降低且存在最优预压力值(400N)使得岩石强度最低。缩短振动频率与岩石固有频率的差值有利于提高超声波振动碎岩效率。  相似文献   

Geology and Geochemistry of Maoling Gold Deposit, Gaixian, Liaoning Province     

Qin Dajun  Cai Xinping  Wan Jie  Xu Xingwang  Zhang Baolin 《中国地质大学学报(英文版)》1999,10(1):86-88

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