Engineering characterization of hydraulic properties in a pilot rock cavern for underground LNG storage

Feasibility of storing LNG in a lined rock cavern was evaluated using a pilot cryogenic rock cavern constructed in Daejeon, Korea. The pilot program included hydrogeological and engineering characterization of the rock mass around the cavern, design and construction of a drainage system, and pilot operation of the cryogenic cavern. An appropriate drainage system is most important to protect the containment system of LNG from thermal shocks due to ice lenses and hydrostatic pressure of groundwater. As a part of the pilot program, this study focused on the evaluation of hydraulic and engineering properties of the rock mass around the cavern. For this purpose, engineering logging of the rock cores, single and cross-hole hydraulic tests, and recharge/drainage tests were performed using seven drilled holes with different trends and plunges. Three main joint sets were found from the logging of the rock cores, acoustic borehole televiewer, and window mapping. The orientations of the three major joint sets were 60/209, 40/171, and 29/331, which can provide the main groundwater flow paths. Mean RQD values ranged from 56 to 88, which were classified as fair and good, although varying with depth along single boreholes. Hydraulic conductivity from the single and cross-hole hydraulic tests estimated in the order of 10⁻⁶ or 10⁻⁷ m/s and corresponding transmissivity ranged between 10⁻⁵ and 10⁻⁶ m²/s. Permeable intervals identified from the hydraulic tests were mostly located above the cavern roof. Below the roof, the permeable zone was difficult to observe. According to the hydraulic communication tests performed for some designated intervals, hydraulic connection between boreholes was highly varied with depth or location, which indicated a very different distribution of water conducting joint sets along the boreholes. When water was injected at R1 with constant or varying flow rates, monotonous and stable seepage was observed at observation boreholes. From this, some stable drainage was expected even in relatively heavy rainfalls. When designing the drainage system of the cavern, the drainage holes should be orientated to maximize frequency of encountering the major joint sets and the permeable intervals identified from this study.     

Wind-wave affected phosphate loading variations and their relationship to redox condition in Lake Taihu

Variation of wind speed and the physico-chemical parameters, such as dissolved phosphate, ferrous and manganese in lake water were observed on site. Together with the chemistry analysis and simulated experiment in lab, the change of phosphate concentration in lake water was analyzed. The variation of ferrous/phosphate ratio explained that along with the enhancement of wind-wave effect and the oxidation ability of lake water, the effects of co-precipitation and removal of dissolved phosphate and iron in the lake water were reinforced. The ferrous/phosphate ratio in pore water was less than 2.0, demonstrating that the dissolved phosphate can be released into the overlying water. But, in the lake water, the stability of phosphate was controlled by the water dynamics. The phosphate release experiment showed that molecular release was only part of the whole and the direct discharge of phosphate in the pore water was also a part. The mineralization and biological process of suspended particulates in the water may be another important reason for the whole phosphate loadings.     

Alkaline phosphatase activity and the phosphorus mineralization rate of Lake Taihu

The phosphorus fractions, the alkaline phosphatase activity (APA) and other water chemical parameters were concomitantly monitored from April 2003 to October 2004 in different ecotype sites of Lake Taihu. During the stages of algae growth, the phosphorus fractions and their relationships with APA in different ecotype sites were discussed and the phosphorus mineralization rate was calculated. In the water of Lake Taihu, most of the phosphorus (70.2%) could be attributed to the suspended particulate phosphorus, while the dissolved reactive phosphorus (DRP) seems to contribute less than 7%. About 58% of the total phosphorus, however, can be hydrolyzed as inorganic phosphate to compensate for phosphorus deficiency of algae and bacteria growth. During the different algae growth stages, the APA and its Kinetic parameters were varied significantly between different ecotype sites of Lake Taihu. This trend is also visible by comparing the phosphorus mineralization rate, and the most rapidly phosphorus turnover time is only several minutes. The fast recycle of phosphorus can, to some extent, be explained that the phosphorus source of algal blooms. The phytoplankton seems to compensate for phosphorus deficiency by using the alkaline phosphatase to hydrolyze phosphomonoesters.     

土地利用更新调查现状图制作中的若干关键技术

为满足各项管理工作深入开展对土地利用现状调查提出的新要求,江苏省很多地区组织开展了土地利用更新调查工作。而标准分幅土地利用现状图的制作是土地利用更新调查中的一项重要工作。本文对标准分幅土地利用现状图制作过程中的若干关键技术进行了探讨。     

A new investigation of the peculiar binary star Epsilon Aurigae

We give results of photoelectric photometry and spectral observations of Aur during its 1982–1984 ingress and total eclipse. Narrow-band light curves and variations in radial velocity within a night resulting from autoregression analysis all indicate short time scale variations in the F supergiant primary on the order of hours or fractions thereof. Fluctuations with an amplitude of ±25 Km/s and a period of 400 d appear to be present in the measured radial velocity of the primary during ingress and totality. Obvious changes in the H profile were also observed: around the second contact of the total eclipse, there was emission in the blue wing; while around the third contact of the atmosphere eclipse, there was emission in the red wing.     

A lateral soil resistance model for XCC pile in soft clay considering the effect of the geometry of cross section

In this paper, a series of well-calibrated finite-element analyses are performed to quantify the influence of the geometry of cross section on the load transfer mechanism of X-section Cast-in-place Concrete (XCC) pile under lateral load, aiming to propose a lateral soil resistance model for XCC pile in soft clay. Based on the results of the numerical parametric analysis, the failure mechanism of soil flow and the ultimate lateral soil pressure are investigated to reveal the underlying mechanism that controls the cross-section geometry-dependency response. Finally, a general p-y formula for XCC pile, which can well capture the lateral behavior of XCC pile considering the various cross section geometries, is developed. In addition, compared with the traditional circular cross section pile with the same area, the XCC pile is more effective in terms of resistance to lateral load.

     

Effects of groundwater level on the seismic responses of coral sand ground and superstructure by shaking table tests

Acta Geotechnica - The changes in groundwater level in coral islands are more common than those in inland areas. In this paper, a series of shaking table tests were performed to investigate the...     

Crustal Structure of the Indus-Tsangpo Suture Zone and its Ophiolites, Southern Tibet

<正>The2000-km-long Indus-Tsangpo suture zone(ITSZ)in southern Tibet marks the boundary between the India and Eurasia plates and contains the remnants of the Neotethyan oceanic lithosphere,ophiolitic mélanges,flysch units and continental rocks.Field-based structural analyses and drill core observations from the Luobusa     

面向云计算的网络体系结构下数据传输机制

分析目前云计算架构下的传输机制,针对网络传输机制中缺少对链路上的任务需求的耦合相关性,提出未来面向云计算的网络体系结构下数据传输机制,分别从网络传输延迟、传输可靠性和云节点存储安全性进行研究,并针对每个瓶颈提出相应的修改方法,从而构建了一个支持不同服务质量需求的云架构,该架构支持现有的网络异构融合,满足可控可管可扩展等需求,适用于新型网络通信信息基础设施.     

辽东黑沟地区辽河群成因及其对辽吉造山带构造演化的制约

辽东黑沟地区出露大面积辽河群变质表壳岩系,本文通过对辽河群中浅粒岩、黑云变粒岩、斜长角闪岩以及辽吉花岗岩等岩石系统的岩石学、锆石U-Pb年代学,并结合斜长角闪岩的地球化学特征来制约其原岩形成、变质时代和沉积环境,进而探讨辽吉造山带的大地构造属性。研究区辽河群变质火山岩和侵入其中的辽吉花岗岩锆石U-Pb定年结果显示区内辽河群形成时代早于～2.16Ga,辽吉花岗岩及辽河群变质岩中的变质锆石定年结果显示区内峰期变质年龄为～1.85Ga左右。锆石阴极发光(CL)图像显示区内辽河群变质沉积岩中的锆石具有清晰震荡环带,说明其具有岩浆成因的碎屑锆石特征,锆石U-Pb年龄分布直方图上显示1987Ma、2182Ma、2505Ma的主峰和2080Ma、2658Ma、2732Ma、3000Ma的次峰,峰值年龄与区域上古元古代弧岩浆岩及太古宙基底年龄相吻合,暗示它们为辽河群沉积岩提供了重要物源。区内辽河群斜长角闪岩属于拉斑玄武岩系列,以低TiO_2和低MgO为特征,轻稀土轻微富集,并具有明显P以及轻微的Nb、Ta、Zr亏损,地球化学特征总体类似于MORB,同时兼具IAB的地球化学特征,不同于弧玄武岩和板内玄武岩,显示出有限的俯冲相关流体的交代作用,指示其形成于弧后盆地环境。结合前人对辽吉造山带内古元古代花岗岩和辽河群的研究成果,认为区内辽河群的沉积环境为活动大陆边缘弧后盆地,辽吉造山带的形成演化与弧-陆碰撞有关。