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Numerical analysis of nonlinear dynamic behavior of earth dams

Babak EBRAHIMIAN

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 24-40 doi: 10.1007/s11709-010-0082-6

摘要: A numerical study is conducted to investigate the dynamic behavior of earth dams. The numerical investigation employs a fully nonlinear dynamic finite difference analysis incorporating a simple elastic perfectly plastic constitutive model to describe the stress-strain response of the soil and the Rayleigh damping to increase the level of hysteretic damping. The extended Masing rules are implemented into the constitutive model to explain more accurately the soil response under general cyclic loading. The soil stiffness and hysteretic damping change with loading history. The procedures for calibrating the constructed numerical model with centrifuge test data and also a real case history are explained. For the latter, the Long Valley (LV) earth dam subjected to the 1980 Mammoth Lake earthquake as a real case-history is analyzed and the obtained numerical results are compared with the real measurements at the site in both the time and frequency domains. Relatively good agreement is observed between computed and measured quantities. It seems that the Masing rules combined with a simple elasto-plastic model gives reasonable numerical predictions. Afterwards, a comprehensive parametric study is carried out to identify the effects of dam height, input motion characteristics, soil behavior, strength of the shell materials and dam reservoir condition on the dynamic response of earth dams. Three real earthquake records with different levels and peak acceleration values (PGAs) are used as input motions. The results show that the crest acceleration decreases when the dam height increases and no amplification is observed. Further, more inelastic behavior and more earthquake energy absorption are observed in higher dams.

关键词: earth dam     numerical     nonlinear response     dynamic analysis     earthquake     dam height    

Yield-height correlation and QTL localization for plant height in two lowland switchgrass populations

Shiva O. MAKAJU, Yanqi WU, Michael P. ANDERSON, Vijaya G. KAKANI, Michael W. SMITH, Linglong LIU, Hongxu DONG, Dan CHANG

《农业科学与工程前沿(英文)》 2018年 第5卷 第1期   页码 118-128 doi: 10.15302/J-FASE-2018201

摘要: Switchgrass ( L.), as a model herbaceous crop species for bioenergy production, is targeted to improve biomass yield and feedstock quality. Plant height is a major component contributing to biomass yield. Accordingly, the objectives of this research were to analyze phenotypic variation for biomass and plant height and the association between them and to localize associated plant height QTLs. Two lowland switchgrass mapping populations, one selfed and another hybrid population established in the field at Perkins and Stillwater, Oklahoma, were deployed in the experiment for two years post establishment. Large genetic variation existed for plant biomass and height within the two populations. Plant height was positively correlated with biomass yield in the selfed population ( = 0.39, <0.0001) and the hybrid population ( = 0.41, <0.0001). In the selfed population, a joint analysis across all environments revealed 10 QTLs and separate analysis for each environment, collectively revealed 39 QTLs related to plant height. In the hybrid population, the joint analysis across overall environments revealed 35 QTLs and the separate analysis for each environment revealed 38 QTLs. The findings of this research contribute new information about the genetic control for plant height and will be useful for future plant breeding and genetic improvement programs in lowland switchgrass.

关键词: yield-height     QTL localization     lowland switchgrass    

Influence of nozzle height to width ratio on ignition and NO

Liutao SUN, Yonghong YAN, Rui SUN, Zhengkang PENG, Chunli XING, Jiangquan WU

《能源前沿(英文)》 2021年 第15卷 第2期   页码 431-448 doi: 10.1007/s11708-021-0726-3

摘要: To improve the ignition behavior and to reduce the high NO emissions of blended pulverized fuels (PF) of semicoke (SC), large-scale experiments were conducted in a 300 kW fired furnace at various nozzle settings, i.e., ratios (denoted by / ) of the height of the rectangular burner nozzle to its width of 1.65, 2.32, and 3.22. The combustion tests indicate that the flame stability, ignition performance, and fuel burnout ratio were significantly improved at a nozzle setting of / = 2.32. The smaller / delayed ignition and caused the flame to concentrate excessively on the axis of the furnace, while the larger / easily caused the deflection of the pulverized coal flame, and a high-temperature flame zone emerged close to the furnace wall. NO emissions at the outlet of the primary zone decreased from 447 to 354 mg/m (O = 6%), and the ignition distance decreased from 420 to 246 mm when the / varied from 1.65 to 3.22. Furthermore, the ratio (denoted by / ) of the strong reduction zone area to the combustion reaction zone area was defined experimentally by the CO concentration to evaluate the reduction zone. The / rose monotonously, but its restraining effects on NO formation decreased as / increased. The results suggested that in a test furnace, regulating the nozzle / conditions sharply reduces NO emissions and improves the combustion efficiency of SC blends possessing an appropriate jet rigidity.

关键词: rectangular jet burner     nozzle height to width ratio     ignition characteristics     pyrolyzed semicoke (SC) and bituminous blend     NOx formation    

Long-term dam safety monitoring of Punt dal Gall arch dam in Switzerland

M. WIELAND, G.F. KIRCHEN

《结构与土木工程前沿(英文)》 2012年 第6卷 第1期   页码 76-83 doi: 10.1007/s11709-012-0144-z

摘要: The 130 m high Punt dal Gall dam is located at the Swiss-Italian border in the South-eastern part of Switzerland and was completed in 1969. The dam is founded on highly folded and partially crushed dolomite and limestone formations. A grout curtain with an area of 120,000 m was provided for controlling seepage. For the monitoring of the dam deformations five inverted pendulums were installed in the dam and three in the rock foundation of the right abutment outside of the dam. For a seasonal water level fluctuation in the reservoir of about 60 m the maximum amplitude of the radial displacement is 25 mm, which includes both the effects of the water load and temperature effects. Furthermore a comprehensive geodetic network was established, 57 joint meters were installed and cracks in the crest gallery are monitored by crack meters. There are also thermometers, piezometers and rocmeters. Springs at the left and right banks of the dam are monitored and chemical analyses of the seepage water and springs are performed regularly. The dam is equipped with strong motion instruments and several near-field earthquakes have been recorded in the past. The paper describes the long-term safety monitoring of this 42 years old arch dam. A short description of the Swiss practice in dam safety monitoring and emergency planning is also given.

关键词: dam safety concept     arch dam     dam instrumentation     dam safety monitoring    

我国高坝建设和科技攻关

陈宗梁

《中国工程科学》 2000年 第2卷 第12期   页码 84-89

摘要:

介绍了我国大坝建设的发展和特点,概括了高坝建设中的地质勘探、坝工技术、泄洪消能、坝基处理和髙边坡处理等方面的科技成果和应用水平,展望了我国高坝发展前景并指出今后高坝科技攻关重点。

关键词: 水力发电     高坝     重力坝     拱坝     碾压混凝土坝     面板堆石坝    

Features of seismic hazard in large dam projects and strong motion monitoring of large dams

Martin WIELAND,

《结构与土木工程前沿(英文)》 2010年 第4卷 第1期   页码 56-64 doi: 10.1007/s11709-010-0005-6

摘要: Earthquakes can affect large dam projects in many different ways. Usually, design engineers are focussing on ground shaking and neglect the other aspects. The May 12, 2008 Wenchuan earthquake has damaged 1803 dams and reservoirs, and 403 hydropower plants with an installed capacity of 3.3GW. Among these dams were the 132-m-high Shapai RCC arch dam and the 156-m-high Zipingpu concrete face rockfill dam. These recently completed dams are dam types which, up to now, have not experienced strong ground shaking. The widespread mass movements have caused substantial damage to dams and surface powerhouses in Sichuan. The different features of earthquake hazard are presented, i.e., ground shaking, faulting and mass movements. It is proposed to prepare project-specific safety plans for all dams, which consist of a matrix where the possible hazards and the corresponding countermeasures are listed. The earthquake behaviors of the Sefid Rud, Zipingpu and Shapai dams, which, in the past, have experienced strong ground shaking from nearby earthquakes, are discussed. Finally, the need for strong motion instrumentation of large dams is discussed. It is proposed that major dams with large damage potential, dams located in areas of high seismicity, and dams showing signs of abnormal behavior be equipped with strong motion instruments.

关键词: seismic hazard     arch dam     concrete face rockfill dam     strong motion instrumentation     reservoir-triggered seismicity     Wenchuan earthquake    

Key problems and solutions in arch dam heightening

Zuoguang FU, Yunlong HE, Sheng SU

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 98-104 doi: 10.1007/s11709-010-0004-7

摘要: The dam heightening, which is an effective way to increase reservoir volume, has been paid close attention by engineers. Three problems should be dealt with when an arch dam needs to be heightened: stress state getting worse at dam heel, cracking on new added concrete dam surface, and weak bonding between new added concrete and old dam. Taking Geba arch dam as an example, these problems are examined in details through simulation analysis by the finite element method. The tensile stresses on dam’s surface and joint face that have certain relations to the dam heightening can be controlled by some measures.

关键词: arch dam     heighten     tensile stress     finite element method    

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

Peter TSCHERNUTTER

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 63-70 doi: 10.1007/s11709-010-0016-3

摘要: This paper demonstrates the difficulties in determining the relevant material parameters for a valuation of the deformation behavior of the up- and downstream dam shell by means of an embankment dam of medium height. Laboratory as well as field tests on solid rock-fill material were performed before the beginning of construction. During the construction the properties of the available rock-fill changed from solid to soft materials. This gave rise to the necessity of adjusting the dam design of the downstream dam shoulder. Several times higher dam settlements as well as significant differential settlements between the up- and downstream dam shell were observed during construction and operation. Apart from this situation, the dam has been operated for nearly 20 years and the behavior of the water barrier has been very good.

关键词: embankment dam     bituminous concrete membrane     rock-fill material properties     deformation behavior    

Evaluation method of dam behavior during construction and reservoir filling and application to real dams

Yuji KOHGO, Akira TAKAHASHI, Tomokazu SUZUKI,

《结构与土木工程前沿(英文)》 2010年 第4卷 第1期   页码 92-101 doi: 10.1007/s11709-010-0009-2

摘要: In this paper we analyzed a real fill-type dam, named the Minami-Aiki Dam, to verify a numerical consolidation method with an elastoplastic model for unsaturated soils. The validities were conducted by comparing the analyzed and measured values during construction and impounding. The settlements calculated showed good agreement to those observed. Though the changing patterns of the measured and calculated pore water pressures were similar, the amounts of pore water pressures induced by the self-weights of embankment and the dissipation speeds were different. The earth pressures measured at the bottom of the core zone showed good agreement with those calculated. This method is valid for estimating behavior of fill-type dams during construction and impounding.

关键词: fill dam     consolidation analysis     unsaturated geo-materials     impounding     construction    

Analysis of arch dam deformations

Franz PERNER, Pius OBERNHUBER,

《结构与土木工程前沿(英文)》 2010年 第4卷 第1期   页码 102-108 doi: 10.1007/s11709-010-0012-7

摘要: Predicting “regular” dam deformations for prevailing conditions and comparing them with observed deformations is an essential part of dam surveillance. In many cases prediction and comparison are carried out automatically and an alarm is triggered in the case of larger deviations.The main contributors to the deformations of arch dams are water loading and the fluctuation of concrete temperature. In general, the deformations exhibit an instantaneous elastic part, a time dependent reversible part and an irreversible part. Prediction of dam deformations can be based on deterministic models, purely statistical models or so-called hybrid models, which are a combination of the first two. Deterministic models rely on static analyses, statistical models on the statistical analysis of previous deformation data.For annual reservoirs, both water loading and temperature vary in cycles over a period of one year and it is extremely difficult to identify the various factors contributing to an observed deformation. This is particularly true for time-dependent reversible displacements due to the water loading and the portion caused by temperature variation.The present article deals with the analysis of arch dam deformations based on hybrid models. Particular attention is given to the analysis of the deformations due to temperature fluctuation and to the long-term deformations. The proposed procedure is employed for the analysis of the deformations of the 186 m high Zillergruendl arch dam.

关键词: arch dam     analysis     Zillergruendl     concrete temperature     hybrid model    

胶结颗粒料坝——环境友好的新坝型

贾金生, Michel Lino, 金峰, 郑璀莹

《工程(英文)》 2016年 第2卷 第4期   页码 490-497 doi: 10.1016/J.ENG.2016.04.003

摘要:

笔者于2009年提出了胶结颗粒料坝的概念,目的在于修建更安全、更经济的环境友好的大坝。该坝型包括胶结砂砾石坝(曾用名胶凝砂砾石坝)、堆石混凝土坝(或胶结堆石坝)和胶结土坝。本文基于研究和实践,进一步阐述了胶结颗粒料坝的概念和原则,介绍了胶结砂砾石坝、堆石混凝土坝和胶结土坝的新进展。

关键词: 胶结颗粒料坝     胶结砂砾石坝     堆石混凝土坝     胶结堆石坝     胶结土坝     材料特性    

Hongshiyan Landslide Dam Danger Removal and Coordinated Management

Ning Liu

《工程管理前沿(英文)》 2014年 第1卷 第3期   页码 308-317 doi: 10.15302/J-FEM-2014041

摘要: This paper takes an overview of the Hongshiyan landslide dam triggered by an earthquake near Ludian County in Zhaotong City, Yunnan Province, introduces how the danger removal plan is drafted and implemented, and analyzes the outcome of its implementation. The paper then explains the significance and effect of coordinated management in the event of natural disasters and other public safety emergencies, and discusses ways to improve coordinated management.

关键词: the Zhaotong Ludian earthquake     danger removal of the landslide dam     coordinated management    

混凝土大坝加高施工关键技术研究

周厚贵

《中国工程科学》 2012年 第14卷 第7期   页码 87-92

摘要:

以国内外混凝土坝加高工程施工实践为基础,系统总结混凝土重力坝后帮整体式加高施工中的4项关键技术,即混凝土原材料及配合比、新老混凝土结合、原有结构体的控制拆除与转移、施工期资源的时间与空间调配。针对其中的每一项关键技术,分析了施工技术难点与特点、施工技术要求,并总结了技术措施和解决策略,以期为同类型工程建设提供参考与借鉴。

关键词: 施工技术     坝体加高     混凝土坝     水利水电工程    

Challenges of high dam construction to computational mechanics

ZHANG Chuhan

《结构与土木工程前沿(英文)》 2007年 第1卷 第1期   页码 12-33 doi: 10.1007/s11709-007-0002-6

摘要: The current situations and growing prospects of China s hydro-power development and high dam construction are reviewed, giving emphasis to key issues for safety evaluation of large dams and hydro-power plants, especially those associated with application of state-of-the-art computational mechanics. These include but are not limited to: stress and stability analysis of dam foundations under external loads; earthquake behavior of dam-foundation-reservoir systems, mechanical properties of mass concrete for dams, high velocity flow and energy dissipation for high dams, scientific and technical problems of hydro-power plants and underground structures, and newly developed types of dam-Roll Com pacted Concrete (RCC) dams and Concrete Face Rock-fill (CFR) dams. Some examples demonstrating successful utilizations of computational mechanics in high dam engineering are given, including seismic nonlinear analysis for arch dam foundations, nonlinear fracture analysis of arch dams under reservoir loads, and failure analysis of arch dam-foundations. To make more use of the computational mechanics in high dam engineering, it is pointed out that much research including different computational methods, numerical models and solution schemes, and verifications through experimental tests and filed measurements is necessary in the future.

关键词: reservoir     engineering     hydro-power development     state-of-the-art computational     earthquake    

Embankment dam foundation analysis for the decrease of internal erosion likelihood

Marc SMITH

《结构与土木工程前沿(英文)》 2012年 第6卷 第4期   页码 431-436 doi: 10.1007/s11709-012-0183-5

摘要: A zoned embankment dam is founded on clay underlain by a sand deposit. Major seepage phenomena were noticed in the foundation downstream from the dam where the vertical seepage forces in the sand layer were expected to exceed the downward forces due to the overlying clay. Modern technologies were applied to delineate critical zones to help design optimal rehabilitation measures. A global electromagnetic survey was carried out to detect and map the main sources, pathways and exits of seepage. Based on these global findings, a more detailed analysis was then conducted to identify zones where thickness of the foundation clay is minimal, pore pressures in sand are higher and thus where the factor of safety against uplift is lower and internal erosion is more likely to occur. Clay thickness evaluation required the determination of land surface as well as clay-sand contact elevations. A laser airborne survey was performed to model the land surface elevation. Data concerning the clay-sand contact elevation came from the interpreted stratigraphy based on a series of boreholes and cone penetration tests. This data was combined in a geostatistical model along with the measured piezometric levels in the foundation. This resulted in a contour map showing factors of safety against uplift over the entire downstream area. The use of modern technologies, namely electromagnetic and laser surveys as well as geostatistical tools, was instrumental in defining the limits of an otherwise spread-out problem and to provide an optimal solution, in terms of costs and effectiveness, for the long-term stabilization of the foundation.

关键词: seepage detection     geostatistical analysis     dam monitoring     internal erosion     LIDAR survey    

标题 作者 时间 类型 操作

Numerical analysis of nonlinear dynamic behavior of earth dams

Babak EBRAHIMIAN

期刊论文

Yield-height correlation and QTL localization for plant height in two lowland switchgrass populations

Shiva O. MAKAJU, Yanqi WU, Michael P. ANDERSON, Vijaya G. KAKANI, Michael W. SMITH, Linglong LIU, Hongxu DONG, Dan CHANG

期刊论文

Influence of nozzle height to width ratio on ignition and NO

Liutao SUN, Yonghong YAN, Rui SUN, Zhengkang PENG, Chunli XING, Jiangquan WU

期刊论文

Long-term dam safety monitoring of Punt dal Gall arch dam in Switzerland

M. WIELAND, G.F. KIRCHEN

期刊论文

我国高坝建设和科技攻关

陈宗梁

期刊论文

Features of seismic hazard in large dam projects and strong motion monitoring of large dams

Martin WIELAND,

期刊论文

Key problems and solutions in arch dam heightening

Zuoguang FU, Yunlong HE, Sheng SU

期刊论文

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

Peter TSCHERNUTTER

期刊论文

Evaluation method of dam behavior during construction and reservoir filling and application to real dams

Yuji KOHGO, Akira TAKAHASHI, Tomokazu SUZUKI,

期刊论文

Analysis of arch dam deformations

Franz PERNER, Pius OBERNHUBER,

期刊论文

胶结颗粒料坝——环境友好的新坝型

贾金生, Michel Lino, 金峰, 郑璀莹

期刊论文

Hongshiyan Landslide Dam Danger Removal and Coordinated Management

Ning Liu

期刊论文

混凝土大坝加高施工关键技术研究

周厚贵

期刊论文

Challenges of high dam construction to computational mechanics

ZHANG Chuhan

期刊论文

Embankment dam foundation analysis for the decrease of internal erosion likelihood

Marc SMITH

期刊论文