Deformation of the central pier of the permanent shiplock, Three Gorges Project, China: an analysis case study

The central pier (CP) is one of the key structures of the permanent shiplock in the Three Gorges Project on the Yangtze River, China. This paper deals with the study of the rock mass deformation of the CP of the second shiplock under various operation conditions. Numerical simulations using the 2-D distinct-element method and 3-D finite-element method are applied to analyze the rock mass deformation. Also, time-series analysis and gray system theory are used to predict the trends of rock displacements based on in situ measured data. The results can be summarized as follows: (1) the main deformation of the rock mass in the CP occurs after excavation completion, while the shiplock is in operation, the dominant displacements mainly occurring on both sides of the northern chamber, developing generally towards the chamber; (2) the horizontal displacement varies with the process of excavation, and is in a steady state after excavation, and during operation of the shiplock the displacement is slightly decreased; (3) the horizontal displacement parallel to the axial line of the shiplock occurs downstream; and (4) the vertical displacement occurs during excavation, and then subsidence with various values takes place in different parts of the CP for different operation conditions.     

Assessment of rock mass characteristics and the excavation disturbed zone in the Lingxin Coal Mine beneath the Xitian river, China

Safe production and induced hazard prevention in coal mines mainly concern problems in the excavation disturbed zone (EDZ), but coal mining can also make a significant impact on the environment. Comprehensive techniques using a borehole TV viewer system, electrical logging, and monitoring of drilling fluid leakage offer the ability to identify changing geological conditions and the location of any nearby abandoned mining workings. The inner collapsed zone and the expanding height of the crack zone transmitting water plus their spatial distribution after excavating the superincumbent coal seam stratum are determined at no. L3414 workings, Lingxin Coal Mine beneath the Xitian river, China. An integrated system of GIS-based on a stochastic model, which has been developed for the prediction of dynamic subsidence coupling the time function and probabilistic integral method, is verified through practice at the Lingxin Coal Mine. This development has greatly expanded the ability of the mine operator to characterize previously inaccessible areas of the mine, providing a reliable basis for safe mining and prevention of induced-hazards to ensure high production mining underneath the river bed.     

三峡工程永久船闸高边坡岩体变形声发射监测

岩体声发射检测是当今国内外积极开发研究的岩体动态监测新技术之一,为了保证三峡船闸顺利建设,在建设过程中采用了声发射技术对船闸高边坡进行全天候在线监测。声发射作为动态监测技术在大型边坡岩体动态监测中具有明显优势。本文将小波变换和神经网络应用到声发射检测之中,能够准确地对岩体稳定性进行预测预报。现场监测表明,利用声发射技术对大型船闸高边坡岩体稳定性及其发展趋势和边坡支护效果,作出了符合实际的评价和有效的预测预报。     

三峡工程二期上游围堰的帷幕灌浆

三峡工程二期上游围堰防渗墙下帷幕灌浆是围堰基础防渗处理的主要形式。在防渗墙与基岩接触带以及基岩内的不同风化带岩体内,均进行了帷幕灌浆。根据帷幕灌浆的大量资料,综合分析研究接触带以及堰基基岩不同风化带内的帷幕灌浆的特征、透水性与岩体的可灌性关系、外冒漏浆控制因素以及帷幕形成后防渗的可靠性。     

Nutrient characteristics in the Yangtze River Estuary and the adjacent East China Sea before and after impoundment of the Three Gorges Dam

From November 2002 to 2006, five cruises were undertaken in the Yangtze River Estuary and the adjacent East China Sea to compare the nutrient concentrations, ratios and potential nutrient limitation of phytoplankton growth before and after impoundment (June 2003) of the Three Gorges Dam (TGD). Concentrations of dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP) and total nitrogen (TN) exhibited an increasing trend from 2002 to 2006. In contrast, total phosphorus (TP) concentration exhibited a decreasing trend. The mean concentrations of DIN, SRP, and TN in the total study area increased from 21.4 µM, 0.9 µM, and 41.8 µM in 2002 to 37.5 µM, 1.3 µM, and 82.2 µM in 2006, respectively, while TP decreased from 2.1 µM to 1.7 µM. The concentration of dissolved reactive silica (DRSi) had no major fluctuations and the differences were not significant. The mean concentration of DRSi in the total study area ranged from 52.5 to 92.3 µM. The Si:N ratio decreased significantly from 2.7 in 2002 to 1.3 in 2006, while TN:TP ratio increased from 22.1 to 80.3. The area of potential P limitation of phytoplankton growth expanded after 2003 and potential Si limitation appeared in 2005 and 2006. Potential P limitation mainly occurred in an area of salinity less than 30 after 2003, while potential Si limitation occurred where the salinity was greater than 30. By comparison with historical data, the concentrations of nitrate and SRP in this upper estuary during November 1980-2006 increased obviously after impoundment of TGD but DRSi decreased. Meanwhile, the ratios of N:P, Si:N and Si:P decreased obviously.     

长江三峡库区移民城市发展与道路交通建设的互动关系

长江三峡工程促进了库区移民城市的快速发展,区域与城市道路交通的建设发挥了重要作用。文章通过分析移民城市道路建设的主要影响因素,以及与城市协调发展中存在的问题,从山地城市特征、内外交通衔接及道路建设的技术措施等方面,总结移民城市建设与道路交通的互动关系。     

三峡二期工程右纵上游坝面裂缝处理质量控制

介绍裂缝处理方案及项目实施过程中,监理工程师根据现场施工特点,及时规范现场验收签证程序,制定施工质量管理办法,并对裂缝处理各施工工序严格把关,有效地保证了裂缝处理施工质量。     

长江三峡库区野果植物资源区系特征分析

根据"长江三峡库区野果植物资源数据库",采用植物区系分析方法,对长江三峡库区野果植物资源区系特征进行了系统分析和研究,得出以下结论:库区野果植物资源在库区植被中占据相当的优势;长江三峡库区野果植物中主要成分为含10种以上的大科和大属;分布区类型分析表明库区野果植物与热带植物区系和北温带植物区系有一定的联系:拥有丰富的特有科属植物种类.     

三峡工程的防排水措施与材料

介绍了三峡工程中大坝、永久船闸基础及一些建筑物的防排水措施和所用材料。     

三峡库区某高切坡稳定性分析与治理措施

对三峡库区某高切坡的稳定性进行定量分析计算,并对该高切坡的加固与防护措施进行了施工图设计。首先,根据高切坡的特点将其分为3个区段,分析了高切坡变形的地质条件和边坡滑移模式,针对不同的滑移破坏类型提出相应的稳定性计算方法。然后,对该高切坡多个典型地质剖面,在天然状态和暴雨工况下分别进行稳定性计算,得到其安全系数为0.939～1.268,表明该高切坡在暴雨工况下的稳定性较低。最后,在定量评价边坡稳定性的基础上,对高切坡的3个区段,分别采取清除危岩体、锚杆加固、挡土墙固脚与挂网喷射混凝土护坡等综合治理措施,以增强边坡的整体稳定性。实践证明,这些措施可以消除高切坡滑移的安全隐患,工程治理效果良好。     

浅谈三峡库区小城镇的传统街道

从三峡库区小城镇的地形特征和居民生活方式入手，分析了小城镇传统街道的平面和空间构成，以及其所带来的生态效应，从而提出了尊重地形、继承传统、独具特色的街道美学。     

Genesis and stability of the Zhoujiawan landslide,Three Gorges,China

The development of the Three Gorges project has resulted in the study of a number of landslides along the Yangtze River. This paper discusses three landslides in the Huanglashi group, some 66 km upstream of the Three Gorges dam. It describes the development and inter-relationship of these landslips, which occurred on the concave meander of the river where steep slopes were created by uniclinal shifting as incision took place. Finite element analysis was used to assess the most likely zone in which future failures will occur.      

三峡库区层状岩体高切坡的工程防护研究

根据三峡库区层状岩体高切坡的特性及分布,提出了层状岩体高切坡存在的四种主要破坏模式,即坡面风化剥蚀、坡脚侵蚀、顺向滑移、崩塌掉块。根据这四种不同的破坏模式,提出了相应的防护措施,对于三峡库区高切坡的工程防护具有一定的指导作用,有利于更好地防灾减灾。     

析三峡库区城市发展应注意的几个问题——以万州为例

论文以万州为例分析了三峡库区城市在发展过程中应注意的一些问题,有助于归纳与总结三峡库区山地城市及临江城市的建筑空间特色,探讨并展望相关城市的发展趋势。     

Significance of outward dipping strata in argillaceous limestones in the area of the Three Gorges reservoir,China

Re-location of the town of Fengjie due to the impounding of the Three Gorges reservoir involved some significant excavations into the valley slopes. It was noted that the mainly calcareous strata in gullies had a northerly dip while in the excavation the dips were sub-horizontal and even southerly, towards the Yangtze River. The paper discusses the process which leads to this change in dip in the superficial strata. This is particularly significant where orthogonal sub-vertical discontinuities are present such that gravitational effects result in blocks toppling out of the free face.     

Impacts of China's Three Gorges Dam Project on net primary productivity in the reservoir area

China's Three Gorges Dam Project (TGP) is the world's largest hydroelectric power project, and as a consequence the reservoir area is at risk of ecological degradation. This study uses net primary productivity (NPP) as an important indicator of the reservoir ecosystem's productivity to estimate the impacts of the TGP in the local resettlement region of the Three Gorges Reservoir Area (TGRA) over the 2000-2010 period. The modeling method is based upon the Carnegie Ames Stanford Approach (CASA) terrestrial carbon model and uses Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data for modeling simulation. The results demonstrate that total NPP in the resettlement region decreased by 8.0% (632.8 Gg) from 2000 to 2010. The impact of the TGP on NPP is mainly mediated by land-use change brought about by the large-scale inundation of land and subsequent massive resettlement of both rural and urban residents. Nearby resettlement, land inundation, and relocation of old urban centers and affiliated urban dwellers are responsible for 54.3%, 28.0%, and 5.8% respectively of total NPP reduction in the resettlement region over the study period. The major national ecological projects implemented in the TGRA since 1998 have played a key role in offsetting the negative impacts of the TGP on NPP in the region.     

三峡水利枢纽永久船闸一闸室南侧山体防渗墙施工

针对三峡水利枢纽永久船闸一闸室南侧 1 85m平台山体防渗墙施工的技术难点及技术要求 ,介绍了混凝土防渗墙施工中的槽段划分、造孔、泥浆制备、输送及回收、预埋管固定架的制作与吊放、墙体砼浇筑及一些特殊部位处理的整套施工工艺 ,并对防渗墙施工的质量采用多种手段进行检验与评价 ,结果表明 ,防渗墙施工质量满足设计要求 ,质量优良     

Cyclic response and modeling of saturated silty clay due to fluctuations in reservoir water level of the Three Gorges Dam,China

The deformation characteristics of soil obtained from landslides at the Three Gorges Dam Reservoir have been examined. Due to the annual fluctuation in the water level of the reservoir, landslides around the Three Gorges Dam Reservoir are subjected to cyclic loading. Laboratory triaxial tests have been carried out on silty clay specimens subjected to cyclic changes in pore water pressure. The test results indicate that when the soil is subjected to repeated unloading–reloading with constant deviatoric stress in an overconsolidated state, the silty clay material shows inelastic deformation with the accumulation of irrecoverable strain. To capture this behavior, a constitutive model has been developed to simulate the deformation induced by changes in pore water pressure. This model is based on a modification of Yao et al. (2009)’s model to include the effect of cyclic loading. The model has been used to calculate the shear strain during cyclic loading and for a comparison with the laboratory test results. It has been shown that the proposed model is capable of capturing the deformation response of landslide soil subjected to changes in pore water pressure caused by the fluctuating water level of the reservoir.     

Phytoplankton development and ecological status during a cyanobacterial bloom in a tributary bay of the Three Gorges Reservoir, China

Reservoirs can provide suitable conditions for cyanobacterial bloom development, which may impact on water quality and biological communities. Weekly surveys in a cyanobacterial bloom process were carried out in the mainstream and Xiangxi Bay of the Three Gorges Reservoir (China), from June 6 to July 18 in 2008. By application of the phytoplankton functional group approach, the spatiotemporal pattern, impact factors, and the ecological status based on Q index (assemblage index) were analyzed. The depth of euphotic layer was apparently the key factor driving the phytoplankton functional group variations. Longitudinal patterns of phytoplankton distribution were detected during this bloom: in the beginning phase, groups D (mainly Stephanodiscus hantzschii) and B (Cyclotella stelligera) dominated in the mainstream of the Three Gorges Reservoir and the mouth area of Xiangxi Bay, group Y (Cryptomonas species) dominated in the upper area, while groups J (mainly Pediastrum duplex), F (mainly Sphaerocystis schroeteri) and G (Pandorina morum and Eudorina elegans) were important in other areas; in the mid phase, group M became absolutely dominant in the whole region; and in the ending phase, besides groups M and Y, groups X2 (Chroomonas acuta, Pyramimonas nanella, etc.) and Lo (Ceratium hirundinella) became more important in the lower and upper area respectively. Generally the ecological status was bad, temporally varied with the bloom process. No spatial difference of ecological status was found in the mainstream, while longitudinal patterns in Xiangxi Bay were detected for different phases: firstly a few sites had relatively better status than the others, then nearly all the sites were in the bad condition, and at last the status in the downstream was better than that in the upstream. The longitudinal patterns of ecological status were related to phytoplankton distribution, disturbed by jacking from the downstream and flood from the upstream of Xiangxi Bay.