A COMPARATIVE STUDY ON THE ACTUAL AND ESTIMATED SEISMIC RESPONSE OF KIRALKIZI DAM IN TURKEY

Kiralkizi Dam, a 120 m high earthfill dam located in Diyarbakir city, Turkey, was shaken by a moment magnitude, M _w =4.6 earthquake at an epicentral distance of 8 km, on December 24, 2000, at 13:31 local time. The seismic response of the dam was assessed by using spectral ratios between (i) available crest and foundation records (C/F), (ii) horizontal and vertical components of the recorded motions (H/V), (iii) by performing 2 dimensional finite difference-based seismic response analyses (Flac-2D), and (iv) ID elastic shear beam solutions. First mode of vibration of the dam in the transverse direction by all four methods were estimated in the range of 0.55 to 0.62 second. Similar close agreement was not observed in higher modal periods estimated by H/V technique as compared to the predictions by C/F, Flac-2D, shear beam analysis techniques. Thus, H/V technique was concluded to be useful for the estimation of the fundamental resonance frequency of a soil structure, but not for its higher harmonics as consistent with available limited literature. In the longitudinal direction, natural period of the dam was estimated as 0.28 and 0. 82 second by H/V and C/F techniques, respectively. Such disagreement was explained by (i) differences in the definitions of the estimated periods, (ii) internal impedance contrast of the dam, (iii) contributions of 3D valley effects. Single seismometer record obtained from crest level was found to be inadequate for reliably assessing the response of a dam in the longitudinal direction, and it is recommended to install multiple seismometers both within dambody and the abutments. Last but not least, the results of these analyses were further compared by available accelograms recorded at three earthfill and rocknll dams from Japan. In general, it was concluded that the seismic response of Kiralkizi Dam is comparable and within the prediction ranges of available analyses methods and is consistent with the expected response of a dam this height.     

Geotechnical Reconnaissance of the 2016 ML6.6 Meinong Earthquake in Taiwan

On February 6, 2015, a local magnitude (M_L) 6.6 earthquake struck southern Taiwan, devastating the Tainan area. A field investigation was conducted by a survey team from the National Center for Research on Earthquake Engineering immediately after the earthquake. This paper summarizes the observed geotechnical damage features caused by the earthquake, including liquefaction, slope sliding, levee failure, and dam performance. Several liquefaction sites were observed despite the intensity of ground shaking being moderate (peak ground acceleration, ~0.2 g). Most of these sites were originally old ponds that were backfilled during different periods in the last three to eight decades. Two significant types of damage to the levee of the Tseng-wen River were observed. At the Jianshan site, a typical type of levee damage was observed, in which the level crest subsided and the side slope developed several cracks. At the Rixin site, a flow-type of failure caused tremendous loss of levee (~400 m in total) at three adjacent locations. The levee embankments had “flowed” up to 60 m into the river.     

Assembling dams in Ghana: A genealogical inquiry into the fluidity of hydropolitics

The paper offers a geographical interpretation of the evolving technical, political, and economic intricacy of large dams. It incorporates existing hydropolitical scholarship and the notion of the Chinese Water Machine to reframe dams as assemblages built by specific political, financial and technical processes in particular socioenvironmental regions. The paper examines the continuity of hydropolitical relationships through a genealogical inquiry into the formulation and materialisation of Ghana's three dams: the Akosombo and Kpong dams built during the Cold War, backed by Western lenders and engineering companies; and the Bui dam commissioned in the 2010s, with support from China. Based on fieldwork in Ghana and China, as well as documentary evidence, the paper argues that the thinking, planning and building of dams interconnect the host regime and external techno-financial actors with their floating political-economic interests, but in a durable way. Sometimes, even if little concrete is actually poured, the symbolic power of dams endures, transforms, and at certain times and places expands, through events and discourses of national and international interest groups pursuing their own purposes, albeit with the replacement of influential individuals and powerful institutions, and regardless of the involvement of Western, Chinese and/or other actors. Ruptures exist but do not necessarily break the continuity of dam assemblages. The emergence of an opposition assemblage that battles against dams is a more recent complexity.     

The contentious politics of hydropower dam impact assessments in the Mekong River basin

Since the 1990s, many large hydropower dams have been built in the Mekong River Basin. There has been considerable concern about resettlement and compensation linked to reservoir flooding, as well as the impacts of dams on wild-capture fisheries, riparian livelihoods, and aquatic biodiversity and ecosystems. Anti-dam activists in the Mekong Basin have contested these impacts by claiming that dam impact assessments limit the spatial scale of recognized impact areas in order to reduce both the political backlash against projects and the costs of dam development. In this article, we consider the contentious politics of hydropower dam impact assessments in order to understand how the spatial strategies of anti-dam activists influence the recognized scale of dam impacts. We analyze three of the most contested hydropower projects in the Mekong River Basin: the operational Pak Mun dam in northeastern Thailand, the recently completed Lower Sesan 2 dam in northeastern Cambodia, and the planned Sambor dam on the mainstream Mekong River in Cambodia. We argue that the recognized scale of impacts is in part an outcome of anti-dam activists’ different spatial imaginaries and associated scale frames—along with those of state actors, business interests, and project consultants—that inform activist strategies for mobilizing geographically dispersed people to make claims about dam impacts. Although activists have sometimes challenged the spatial extent of project impact assessments, they have also sometimes inadvertently adopted strategies to contest dams that have reproduced project scale frames favorable to dam proponents.     

Investigation of the Optimum Height of Railway Embankments during Earthquake Based on Their Stability in Liquefaction

One of the most reported problems in the railway embankments is loss of their overall stability and major settlements due to liquefaction. Although several studies have been made on the stabilization of embankments, the effects of the influencing parameters on the stability of embankments during liquefaction have not been sufficiently investigated. The series of two dimensional plane strain finite element (FE) models were developed using multi yield surface plasticity model namely Prevost. The results were represented and discussed in terms of foundation excess pore pressure, embankment settlements and their failure modes. By analyzing the results, the optimum height of embankment which minimizes the settlement and failure cracks was derived.     

Historic Barrel Vaults Undergoing Differential Settlements

ABSTRACT

A principal reason of damage in historic masonry vaults consists in relative displacements of the vaults’ abutments. Excluding the case of seismic-induced damage, cracks are often produced by differential settlements generated by the lateral wall instability or soil degradation (e.g., due to stress concentrations, non-uniform soil stratigraphy, flooding phenomena etc.). When dealing with historic vaults, the effects of long-term deformation processes cannot often be linked directly to causes, which may also be unknown. In this article, the effects of differential settlements on historic masonry barrel vaults are investigated. An efficient 3D contact-based model was developed to reproduce experiments on a scaled pointed barrel vault (representative of a typology of late-medieval barrel vaults in Scotland) under non-uniform differential settlement. First, the numerical model is used to simulate the experimental campaign, achieving good agreement in terms of crack pattern (longitudinal shear) and transverse-longitudinal deformation profiles. Then, further analyses are carried out to gain insight on the effects of several plausible uniform and non-uniform settlement patterns on representative historic barrel vaults. Various settlement configurations were analysed and complex failure patterns observed. This study could help analysts in understanding the nature of on-going deformation process in historic masonry vaults and engineers in the design of strengthening strategies.     

DAMS AND INDIGENOUS PEOPLES IN MALAYSIA: DEVELOPMENT,DISPLACEMENT AND RESETTLEMENT

Large dams have proliferated in Malaysia in recent decades. Constructed mainly to meet mounting domestic demand for water and energy, they have destroyed large tracts of species‐rich tropical rain forest and displaced many already poor and marginalized indigenous groups from their homes and ancestral lands without their consent. Evicted indigenes were promised a better life in resettlement villages, but for the most part this has not occurred. Invariably traumatized by resettlement and widely forced into cash‐based economies for which they were ill prepared, many resettled indigenes suffered from frayed social relationships, high rates of unemployment and enduring poverty, in large part because the authorities failed to internalize project costs. The consequences for indigenous groups of dam‐induced environmental change and development‐forced displacement and resettlement (DFDR) are explored through a critical reading of the literature on four large dams: Sungai Selangor, Babagon, Batang Ai and Bakun. More large dams are under construction and many others have been proposed, resulting in threats to the future well‐being of many indigenous communities. Generally speaking, the experiences of Malaysia's dam‐affected indigenes mirror those of other indigenous minorities in the greater Southeast Asian region.     

大运河宁波段聚落文化遗产保护措施研究

聚落文化遗产是大运河遗产的重要组成部分,与运河兴衰息息相关。宁波段运河聚落文化遗产历史久远,保存类型丰富,历史价值突出。宁波运河的开凿和变迁对运河聚落整体格局的形成、演变和发展关系紧密;同时运河聚落的产生和发展也促进了运河功能的不断完善和运河经济的发展。如何保护好运河聚落文化遗产已经成为重要的研究课题。本文意在梳理宁波段运河聚落文化遗产的构成情况,并对宁波段运河聚落文化遗产的科学保护提出了可行性建议。     

土默特平原聚落分布形态演变及其驱动因素分析(1934—2019)

选取土默特平原1934、1982和2019年的聚落人口数据,运用GIS空间分析法,定性与定量结合分析研究区聚落分布形态演变及其驱动因素,结果表明,1934—2019年土默特平原以小聚落为主,大规模聚落数量和比例逐年增加,人口等级结构由“扁平”向“长高”金字塔形转变。聚落空间分布整体呈现集聚分布特征,大规模聚落集聚性不显著,其他规模的聚落分布模式由随机向集聚转变,研究区人口极化现象显著;聚落空间分布非均衡发展趋势明显,呈现由极核式向点轴式演变的迹象;聚落网络联系的空间近邻效应显著,人口规模较大的中心城区成为强联系节点。地形、河流、交通是研究区聚落分布形态演变的主要驱动因素,聚落低海拔、邻河流、邻干道、邻城镇的指向性强。该研究便于厘清土默特平原近百年聚落分布形态的演变脉络,为当地聚落的空间布局优化与调控提供一定参考价值。     

Effect of the electric field on the equatorial ionospheric plasma distribution

It is known that on a counter electrojet day the noontime electron density at the equator shows enhanced values with no bite-out. The consequences of the absence of the normal equatorial electrojet on the electron density distribution at the equatorial station Kodaikanal (dip latitude 1.4°N, long. 77.5°E) and at an anomaly crest location Ahmedabad (dip latitude 18°N, long. 73°E) are discussed for a strong electrojet (SEJ) day and a counter electrojet (CEJ) day. The electron density distribution with height for a pair of SEJ and CEJ days at the two equatorial stations Kodaikanal and Huancayo (dip latitude 1°N, long. 75°W) are studied. The F-region peak height, hm and the semi-thickness parameter ym on the SEJ day followed a similar variation pattern. On the CEJ days ym exhibited a substantially low and mostly flattened daytime variation compared to the peaked values on the SEJ day. An attempt is made to interpret these differences in terms of the changes in the vertical drift pattern resulting from the E × B drift of plasma at the equator and the varying recombination rate β, which is also a height dependent and a local time dependent parameter.     

Seismic Analysis of Masonry Gravity Dams Using the Discrete Element Method: Implementation and Application

Much research in recent years has focused on the seismic analysis of concrete and earthfill dams, and few works have addressed the case of masonry dams. The structural behavior of masonry dams is controlled essentially by its discontinuous nature, which may induce significant nonlinear response during an intense earthquake. In this article, a numerical tool based on the Discrete Element Method is presented, aimed at the static, dynamic, and hydromechanical analysis of masonry gravity dams. The use of discontinuous models is mandatory for the study of failure mechanisms involving the masonry discontinuities, the dam-rock interface or the rock mass joints. The Discrete Element Method is able to assemble continuous and discontinuous meshes simultaneously in the same model, providing a versatile tool to consider various assumptions and levels of analysis, ranging from simplified to detailed structural representations. A comprehensive study of the seismic behavior of Lagoa Comprida Dam, located in Portugal, is presented. Both continuous and discontinuous models were developed to assess the main failure mechanisms, including overstress, partial and global sliding, and overturning.     

关中中心聚落地域结构的形成与演变

本文论述了关中地区县级以上中心聚落体系的形成与地域结构的演变过程。指出:关中地区中心聚落体系的真正形成是以秦推行郡县制为标志,到秦统一已基本形成完整的首位城市与县级聚落二级制体系。从东汉开始,关中中心聚落的等级结构则由二级逐渐变为三级制;中心聚落在空间分布上,表现为由沿渭河两岸的密集型向政治色彩较浓的区域均衡化转变,唐以后则向以经济为主的工商城市体系转变。此外,作为首位城市的西安(长安)城,在城市地域结构上也有变化,最显著的是政权中心区与市场区的区位空间发生了几乎完全相反的变化。     

Reconstructing Cycladic Prehistory: Naxos in the Early and Middle Late Bronze Age

The lack of published deposits from Cycladic settlement contexts has been a serious setback to our knowledge of Cycladic prehistory, as it has led to inflexible 'pan-Aegean' models of cultural history, imposed on the islands without consideration of local particularities and regional variations. Naxos, the largest and most central of the Cyclades, is a prime example of an important island, whose cultural history, especially in the early and middle Late Bronze Age (roughly from the sixteenth to the thirteenth centuries BC), is not well known. In the present article the author reconstructs the stratigraphic and chronological sequence of the island's only excavated settlement at Grotta, examines the development of settlement pattern on Naxos, and attempts to assess the position of the island in the Aegean during the periods in question. It is suggested that the fluctuations in the number of settlements and the changes in settlement pattern of the island could be tied to the degree of integration of the island into the Minoan and Mycenaean exchange networks. In periods of limited integration (LC I/II and LH IIIB) the settlement pattern consists of one or two important centers (Mikre Vigla and/or Grotta) and a number of small settlements dispersed in the interior of the island. In periods of advanced integration (LH IIIA1-IIIA2), a process of nucleation takes place, in which small settlements are abandoned, Mikre Vigla declines, and Grotta is established as the only settlement of the island.     

Risks and Consequences in Energy Production

Abstract

The word risk is often used in association with energy production and in some case it is equated with consequences. The distinction is important and has implications for the study of energy system. Failure in a given energy system, such as nuclear power or hydroelectric dams, can give rise to human consequences, such a deaths, injuries or disease. The extent of these consequences varies from one system to another. Furthermore, the probability of such failures is a characteristic of the given system. For example, a nuclear reactor or hydroelectric dam may have a probability of one catastrophic failure in x years of operation where x is a large number. The probability multiplied by the number of deaths, injuries and illnesses caused by the failures—the consequences—can be taken as a measure of the risk, or risk index.     

The nature of third-millennium settlement: The example of al-Tikha (Rustaq) an Umm an-Nar site on the Batinah coast of Oman

al-Tikha is a mid to large Umm an-Nar (c. 2700–2000 BC) settlement situated near Rustaq at the back of the Southern Batinah coastal plain in the Sultanate of Oman that was discovered (or rediscovered) in 2014. The site is unique because its layout and spatial organisation are very largely (possibly completely) visible on the surface. This includes two separate areas of stone-built housing, a large pottery scatter of varying density, three or four typical Umm an-Nar round towers and a small cemetery consisting of at least four tombs, along with a few other features. The layout of the site is described and discussed in detail, in particular, in relation to what it might tell us about the nature of Umm an-Nar settlement and social organisation more generally. The location of the site within a pattern of repeating Umm an-Nar settlement along Wadi Far (Wādī al-Farʿī) is also described and discussed.     

Stable isotope reconstructions of shellfish harvesting seasonality in an estuarine environment: implications for Late Holocene San Francisco Bay settlement patterns

Seasonality estimates based on stable isotope analyses of shellfish remains has been an important thrust of settlement pattern reconstruction, allowing researchers to place people on the landscape at points in space at different times of the year. In exposed coastal settings seasonality reconstructions are typically dependent on annual changes in water temperature. This paper has two goals. First, we continue development of a method for determining shellfish harvest seasonality in estuarine environments where annual salinity changes, not temperature, drive isotopic variation. Second, we contribute to settlement pattern studies by showing how small and large sites can be linked into a single system by examining different site types and shellfish species. Our case study focuses on the Late Prehistoric period of the San Francisco Peninsula, includes a large shellmound (CA-SMA-6) and an ephemeral camp (CA-SFR-171), and examines clam (Macoma spp.) and mussel (Mytilus spp.) harvesting. In this case, data support a fission-fusion settlement pattern, with periods of dispersal during late winter through early summer and aggregation in late summer through early winter.     

Evaluation of the Nonlinear Seismic Response of an Earth Dam: Nonparametric System Identification

A system identification framework is proposed to investigate the nonlinear dynamic response of massive earth dams using the seismic motion recorded by a sparse array of accelerometers. The framework includes a methodical step of nonparametric analyses to characterize the involved loading conditions and response mechanisms. This nonparametric step provides essential information to reduce the indeterminacy of the associated parametric identificatin problem and ensure a proper model selection, calibration, and validation. The proposed framework was applied to the Long Valley earth dam (California) and benchmarked using records of a series of 1980 earthquakes. This article presents the conducted correlation, spectral motion reconstruction, and nonparametric stress-strain analyses. These analyses revealed a complex three-dimensional dynamic response marked by non uniform boundary conditions and a shear stress-strain behavior slightly less nonlinear than what was observed in triaxial tests of soil samples taken from the dam core.     

The Regular Component in Settlement Patterns as Shown on a Map

The author uses the concept of entropy from information theory to test the application of Christaller's hexagonal trade-area concept to actual settlement patterns. The entropy measure is used to separate the settlement pattern into its hexagonal and random components, just as incoming radio signals would be separated into the original outgoing signals and noise interference. Medvedkov derives formulas for two methods, one using the density of points within cells of a lattice, the other using the nearest-neighbor technique. The entropy approach is tested in seven actual situations, including three control situations, and shows the regular, or hexagonal, pattern to be the predominant component in five out of seven cases.     

山西灵石县静升村明清聚落格局的变迁

聚落格局是历史聚落地理研究较少关注的一个对象。山西灵石县静升村“九沟八堡十八巷”的聚落格局形成历经元末明初各沟巷的初步开发,明中后期至清初的边界拓展与内部扩建,以及清中后期内部格局的充盈及跨河“南侵”三个阶段。这其中地理环境、宗族势力、战乱匪患和国家政策等因素产生了重要影响。静升村的个案研究表明,聚落格局的形成与发展是一个动态变迁的历史过程,而聚落庙宇以及标志性建筑物的创建历史成为考察的重要指标。现今加强乡村聚落格局的研究仍将是中国乡村聚落形态研究继续深入拓展的趋势之一。     

SEISMIC SAFETY OF AGED CONCRETE GRAVITY DAMS CONSIDERING FLUID-STRUCTURE INTERACTION

It is important to predict the behaviour of an aged concrete gravity dam during an earthquake and to assess its degraded capacity to withstand future earthquakes, so that remedial measures can be taken at the right time. The assessment of operating and ageing dams is more important, since the analyses procedures may become obsolete and state of the art may change since the time of construction. In this paper, an approach to include the time dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic damage index is presented. An effective numerical algorithm for seismic analysis of a concrete dam in the vicinity of an infinite reservoir with the application of damage mechanics considering fluid-structure interaction is presented. The performance of an aged dam with a known percentage of isotropic or orthotropic damage due to seismic excitation is studied.