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281.
本文以某水利工程闸门井竖井开挖为例,中导井开挖尺寸2 m×2 m,通过实践总结研究,介绍了竖井中导井施工开挖的一种新方法——中导井一次爆破成井法,着重介绍了中导井如何一次爆破贯通的技术措施。本工法采用中导井一次爆破成井和竖井周边扩挖相结合。开挖方法采用深孔爆破法,通过爆破方案设计、施工前准备、机械钻孔、装药、联线、爆破、炮后安全检查等工艺,先对中导井进行一次爆破开挖成型,再对竖井周边岩体自上而下采用浅孔多循环爆破扩挖成型,最终形成竖井中导井。 相似文献
282.
????????????????????д?????????????ο????????????????????????С??????????????????????????????????y????С????????????????????о???????????????????????????????????棬????????????????????????????в??????????????????????????????????????????й?????????????????????????λ?????????????????????????????????????????????????????????????????д???????????????????????н?????Ч???? 相似文献
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285.
南海是西太平洋最大的边缘海,地处欧亚板块、太平洋板块和印度洋板块的交汇处.过去通过磁异常条带对比分析南海扩张年龄的研究很多,但是所依赖的资料有限.本文对南海海盆高密度大批量磁异常测量数据进行了系统分析,实现了平面2D磁异常数据的带通滤波处理,消除了短波长噪音和由深部下地壳和上地幔顶部磁源体引起的长波长背景信息,因此突出了海底扩张所引起的磁异常条带.利用CK95地磁倒转模型和Talwani磁异常正演方法,对南海东部和西南次海盆内的重点磁异常测线进行了正演分析.通过对不同测线之间、不同海盆之间以及同一条测线中的正演磁异常与实测磁异常之间进行对比分析,进一步验证了南海东部次海盆的扩张年龄为32~16.5 Ma;西南次海盆可能的扩张年龄仍具有较大不确定性,可能为42~33 Ma或者24~16 Ma.不同的时间模型所依赖的扩张速率的变化情况不同,全扩张速率随时间变化明显,但主要在40~80 km/Ma之间.单纯根据目前的磁异常资料很难确定西南次海盆与东部次海盆之间的扩张次序.单期次扩张模式很难解释中南断裂两侧的构造物理差异,这种差异可能主要受控于其基底岩石成分、岩石磁化率、岩浆活动、扩张速率以及深部物质冷却磁化的影响,基底深度的变化也对观测磁异常的强度有所影响.相对地,大部分扩张后玄武岩海山的存在对观测的磁异常的影响不明显,针对目前磁异常解释中不可避免的多解性问题,需要运用其他不同的手段和方法,譬如大洋钻探和深拖高分辨率磁异常测量等,来实现对南海不同次海盆扩张年龄的精确估计.我们目前的工作是通向对深拖高分辨率磁异常、船测和航测磁异常、以及卫星磁异常综合解释的第一步. 相似文献
286.
《Marine Geodesy》2012,35(1):1-22
AbstractThe deep seafloor is closest to the Earth’s interior and there are complicated interactions in the physical and biological processes of the seafloor. Oceanographic parameters such as temperature, salinity, and ocean current can provide support for climate prediction. Therefore, the long-term observation of the deep seafloor is critical to the study of global climate change and the biodiversity in complex environments. For the requirements of long-term observation and remote data transmission in the deep sea of the South China Sea, a seafloor observation prototype system is designed in this paper as a stand-alone observation platform. We then proposed a date management method based on Controller Area Network to ensure the data quality. Distributed data management can be performed through system layering, and strict data transmission standards are established between each layer. At the same time, aiming at the difficulty of seafloor video data transmission in real-time, a new solution based on satellite communication technology, object detection technology, and high-efficiency compression coding technology of video images is proposed to provide support for seafloor biodiversity research. The observation data from the experiment are given, and these results show that the system can meet the requirements of long-term observation and remote real-time data transmission, and the reliability of the system is verified. 相似文献
287.
288.
一种分层海底反向散射模型 总被引:1,自引:1,他引:0
In order to predict the bottom backscattering strength more accurately, the stratified structure of the seafloor is considered. The seafloor is viewed as an elastic half-space basement covered by a fluid sediment layer with finite thickness. On the basis of calculating acoustic field in the water, the sediment layer, and the basement, four kinds of scattering mechanisms are taken into account, including roughness scattering from the water-sediment interface, volume scattering from the sediment layer, roughness scattering from the sediment-basement interface,and volume scattering from the basement. Then a backscattering model for a stratified seafloor applying to low frequency(0.1–10 kHz) is established. The simulation results show that the roughness scattering from the sediment-basement interface and the volume scattering from the basement are more prominent at relative low frequency(below 1.0 kHz). While with the increase of the frequency, the contribution of them to total bottom scattering gradually becomes weak. And the results ultimately approach to the predictions of the high-frequency(10–100 kHz) bottom scattering model. When the sound speed and attenuation of the shear wave in the basement gradually decrease, the prediction of the model tends to that of the full fluid model, which validates the backscattering model for the stratified seafloor in another aspect. 相似文献
289.
290.
Zhengyu Hou Jingqiang Wang Wenjing Chen Tiegang Li Yanxin Zhang 《Marine Georesources & Geotechnology》2017,35(4):466-471
Based on the core samples collected in different geological tectonic units in the southern South China Sea, the double parameter equations between sediment sound speed and physical parameters were developed. According to the double parameter equations, the influences of physical parameters (porosity, mean grain size, wet bulk density, and clay content) on sediment sound speed were analyzed. To analyze the sensitivity of each parameter in the double parameter equations, the error norm method was introduced. The most influencing physical parameters with relative order were analyzed using the error norm method. These results show that porosity has a major influence on the sound speed, and the most influential physical parameters on sound speed are as follows: porosity > wet bulk density > clay content > mean grain size. 相似文献