Engineering geological studies of the diversion tunnel, focusing on stabilization analysis and support design, Iran

In this paper a detailed engineering geological assessment of rock masses and support design studies at Garmi Chay dam site, has been carried out. This project is located in the northwest of Iran and will be used for flow control and water storage. The diversion tunnel of the dam has a diameter of 5.5 m and a length of 420 m and will be driven in slightly to highly weathered micaschist and trachy andesite rock units. The geological studies include field and laboratory investigations that based on the results; for more exact investigation, tunnel alignment was divided into three geotechnical zones. These zones consist mainly of highly weathered gray micaschists, dark red trachy andesites and slightly weathered gray micaschists, respectively. Then, for every zone, support capacity of rock masses was evaluated by means of empirical and numerical methods. The rock mass classification systems (RMR, Q, GSI, RSR, SRC and RMi), the convergence–confinement method and a 2D finite element computer software, Phase² were used for empirical and numerical method, respectively. According to the results acquired from these methods some stability problems were expected in the tunnel especially in highly weathered micaschist zone, so that in practice two big collapses occurred. Because of high weathering, low constants of rock masses and their soil-like behavior, the stability analysis by analytical method does not give illogical results in lightly weathered micaschist zone. The support system, suggested by empirical method, was applied and its performance was evaluated by means of numerical modeling. After installation the support suggested by Phase² program, the thickness of plastic zone and deformations around the tunnel decreased significantly. Consequently the agreement of these methods with each other was resulted and using combination of them was recommended for more reliable support design.     

单管通信铁塔结构基本自振周期分析及抗震应用

利用ANSYS软件分析了单管通信铁塔结构的基本自振周期特性,针对不同高度和不同圆形外平台数量进行大量参数分析,得出了在不同参数下单管塔的基本自振周期,并通过有限元计算结果拟合出估算单管通信铁塔结构的基本自振周期的实用计算公式,对实际工程的抗震设计工作有一定参考价值.     

跨断层形变测量场地图形分析及设计

在分析了青藏体北缘跨以形变测量场地图形状态的基础上,论述了进行优化设计的必要性及新的图形设计的主要内容：（１）以ＧＰＳ控制整个断裂、以水冷、测距、基线、重力等测量手段监测各个场地测点形成的三维地形物重力变化信息;（２）断层水准、重力按新的标石裂线阵设;（３）断层水平形变可根据运动状态的不同,按“走滑型”和“倾滑型”布设;（４）场地水冷、重力定期水准、重力联测,场地水平没距网定期与区域ＧＰＳ网联测,     

Analytical model for fully three‐dimensional radial dispersion in a finite‐thickness aquifer

Analytical solutions for contaminant transport in a non‐uniform flow filed are very difficult and relatively rare in subsurface hydrology. The difficulty is because of the fact that velocity vector in the non‐uniform flow field is space‐dependent rather than constant. In this study, an analytical model is presented for describing the three‐dimensional contaminant transport from an area source in a radial flow field which is a simplest case of the non‐uniform flow. The development of the analytical model is achieved by coupling the power series technique, the Laplace transform and the two finite Fourier cosine transform. The developed analytical model is examined by comparing with the Laplace transform finite difference (LTFD) solution. Excellent agreements between the developed analytical model and the numerical model certificate the accuracy of the developed model. The developed model can evaluate solution for Peclet number up to 100. Moreover, the mathematical behaviours of the developed solution are also studied. More specifically, a hypothetical convergent flow tracer test is considered as an illustrative example to demonstrate the three‐dimensional concentration distribution in a radial flow field. The developed model can serve as benchmark to check the more comprehensive three‐dimensional numerical solutions describing non‐uniform flow contaminant transport. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluation of building period formulas for seismic design

Building period formulas in seismic design code are evaluated with over 800 apparent building periods from 191 building stations and 67 earthquake events. The evaluation is carried out with the formulas in ASCE 7‐05 for steel and RC moment‐resisting frames, shear wall buildings, braced frames, and other structural types. Qualitative comparison of measured periods and periods calculated from the code formulas shows that the formula for steel moment‐resisting frames generally predicts well the lower bound of the measured periods for all building heights. But the differences between the periods from code formula and measured periods of low‐ to‐medium rise buildings are relatively high. In addition, the periods of essential buildings designed with the importance factor are about 40% shorter than the periods of non‐essential buildings. The code formula for RC moment‐resisting frames describes well the lower bound of measured periods. The formula for braced frames accurately predicts the lower bound periods of low‐to‐medium rise buildings. The formula for shear wall buildings overestimates periods for all building heights. For buildings that are classified as other structural types, the measured building periods can be much shorter than the periods calculated with the code formula. Based on these observations, it is suggested to use C_r factor of 0.015 for shear walls and other structural types. Copyright © 2010 John Wiley & Sons, Ltd.     

盐穴能源储库氮气阻溶造腔气垫控制理论研究

盐穴具有良好的稳定性和密闭性,是储存天然气、石油、氢气等的理想场所。传统水溶造腔采用的油垫阻溶存在阻溶效果差、卤水油污重等问题,无法满足绿色矿山建设要求。气垫作为一种替代品备受关注,但因其起步较晚、控制难度大,加之我国复杂的盐层地质条件,阻碍着其推广应用。为此,首先分析了不同造腔阶段气垫控制特点,然后在对气-液界面处压力平衡分析的基础上提出了不同阶段气垫厚度预测及注气量计算方法,结合某井建槽期实例给出了建议气垫厚度及其波动范围,探明了气垫厚度和注气量随造腔推进的变化规律,最后探讨了气垫阻溶应用相关的关键问题。研究结果表明：建槽期及收顶期以气垫厚度控制为主,建腔期及腔体修复阶段则以气-液界面位置控制为主。建议建槽期平均气垫厚度不低于0.3 m,建槽期初期气垫厚度波动迅速,应设置较大的气垫厚度并及时补注氮气,随后气垫厚度波动趋于稳定,补气时间间隔可逐渐拉长。随造腔时间增加,单次补气量越来越大,累计补气量整体呈线性增长。造腔过程中井口气压及气-液界面处气垫压力先增加后线性减小,应实时监测井口气压变化。气垫阻溶与油垫阻溶成本相近但环境效益显著,可重复利用排出氮气及井口注气设施以节约成本。现场应...     

气象云建设的研究与思考

气象云建设是气象信息化上新台阶的必由之路,加强气象云建设是气象现代化的重要内容之一。根据气象信息化的现状与需求,提出了气象云建设的四条原则,即满足各种气象业务服务和管理需求、有利于提高气象预报预测准确率、集约高效和数据共享的原则。在此基础上,提出了气象云的设计思路:气象云应包括云存储、云计算和云服务,云存储为云计算提供支撑,云存储、云计算为云服务提供支撑。最后,对气象云建设中的数据获取途径进行了概括:一是国外气象数据,二是国内气象观测数据,三是国内加工的产品。     

多波束成像声纳系统低功耗设计

针对多波束成像声纳系统降低系统功耗提高续航能力的要求,从硬件和算法两个方面展开了对系统的低功耗设计。硬件方面通过采用单电源运算放大器(OPA)电路架构对系统调理模块的放大、滤波链路进行了重新设计,实际测试结果表明实现了14.37W的系统功耗降低。算法方面通过提出一种基于圆阵的旋转多波束形成方法,在完成系统多波束设计的基础上实现了85倍的资源优化效果,为信号处理模块的FPGA芯片低功耗选型提供了技术支撑。     

A framework for teaching the timeless way of mapmaking

There are now many opportunities to learn how to make maps through technical training with mapmaking tools, including geographic information systems and web-based mapping services. In cartographic education, two challenges with teaching through practice stem from the disruptive nature of mapmaking tools and the tradition of teaching cartographic principles by rule or convention. This article outlines a framework for a pattern language to organize and share practical information about principles for making maps. The article provides an example pattern for mapmaking and discusses how this framework addresses recurring problems with teaching through practice.