PS材料加固土遗址风蚀试验研究

风蚀是西北干旱地区土遗址破坏的主要动力机制和成因,强烈的风蚀作用致使许多土遗址坍塌殆尽,导致这一不可再生资源的破坏。通过对土遗址的室内和现场风蚀模拟试验研究发现,经PS（高模数硅酸钾）材料加固后土遗址的抗风蚀能力明显增强。室内试验发现,风蚀量随风速的增长而增加、随风蚀时间延长近线性增长,PS材料浓度大于5 %的加固试样,即使风速达20 m/ s时,风蚀量均小20 (kg/ m2)•h,抗风蚀强度提高 6～10 倍。现场模拟试验结果表明,加固材料的入渗深度和用量直接影响加固效果,中浓度PS材料加固的墙面抗风蚀能力最强。因此,选择适当的PS材料浓度、提高加固材料的渗透力是土遗址保护加固的关键,将对西北地区土遗址科学保护的全面开展起到重要的指导作用。     

潮湿环境下古代土遗址的原位保护加固研究

古遗址的保护是文物保护工作中最复杂的问题之一,而土质文物是文物保护中最难保护的文物,所以古代土遗址的保护已在国际上被列为专门的保护项目,而处于潮湿环境下的古代土遗址保护的课题在文化遗产实物和遗迹就地保存和展示领域就更为迫切。浙江良渚文化是中国新石器时代长江流域最重要的史前文化, 塘山遗址位于良渚文化遗址的西北部,选择了PS（硅酸钾）、WD－10（十二烷基三甲氧基硅烷）、WD－S（低聚甲氧基硅烷）、RTV（聚有机硅氧烷+硅酸乙酯）4种保护材料对塘山遗址进行了保护加固实验研究。室内实验和现场实验（2个月,6个月,9个月）的结果都表明,RTV和WD-10防水性优于WD-S,WD-10和WD-S材料仅能作为防水材料,PS材料仅能作为加固材料使用,而RTV则具有较好的加固和防水效果,且加样量越大,强度提高越多。     

Geologic implications and potential hazards of scour depressions on bering shelf,Alaska

Flat-bottomed depression 50–150 m in diameter and 60–80 cm deep occur in the floor of Norton Sound, Bering Sea. These large erosional bedforms and associated current ripples are found in areas where sediment grain size is 0.063–0.044 mm (4–4.5 φ), speeds of bottom currents are greatest (20–30 cm/s mean speeds under nonstorm conditions, 70 cm/s during typical storms), circulation of water is constricted by major topographic shoals (kilometers in scale), and small-scale topographic disruptions, such as ice gouges, occur locally on slopes of shoals. These local obstructions on shoals appear to disrupt currents, causing separation of flow and generating eddies that produce large-scale scour. Offshore artificial structures also may disrupt bottom currents in these same areas and have the potential to generate turbulence and induce extensive scour in the area of disrupted flow. The size and character of natural scour depressions in areas of ice gouging suggest that large-scale regions of scour may develop from enlargement of local scour sites around pilings, platforms, or pipelines. Consequently, loss of substrate support for pipelines and gravity structures is possible during frequent autumn storms.     

Discovering the ancient lakelet of the archeological site of pasargadae in Iran using a multi-layer technique

Pasargadae complex had been the main center of Persian history during the Achaemenian period (560–330 bc), registered as one of the world heritage sites by UNESCO in 2004. This research is an attempt to recognize the natural setting and landscape of Pasargadae during the Achaemenian period, in Iran. The method is based on the application of a multi-layer technique. Collected data by fieldwork, especially in geology, hydrology, and hydrogeology, along with the analysis of aerial data and satellite information provided the baseline information for preparing historic and environmental layers and have made it possible to recognize a natural lakelet in the this area. The results show that the geometry of lakelet together with the ancient river of Pasargadae had been the main elements that formed the character of the site; they were also important in the locations of buildings in the Pasargadae complex.     

Palaeo-karst collapse pillars in northern China and their damage to the geological environments

According to statistics, there are a total of 39 sites of palaeo-karst collapse pillars in Northern China, as well as 3,650 palaeo-karst collapse pillars. Through an overall survey and analysis of the distribution regularities and formation mechanisms of palaeo-karst collapse pillars in the northern coal mine regions, this paper found that the rock formation structures, geological structures, karst characters, underground hydrodynamic conditions of karst and neotectonic movement conditions are basic geological bases for the formation of karst collapse pillars and rule the distribution of them. Karst collapse pillars apparently have three south–north regularities in terms of distribution, and they have resulted in severe damages to geological resources and environment in their distribution areas: mine water inrush causing and coal resources damage and influencing the impounding of reservoirs as well as the stability of dam sites. Based on the basic geological features of palaeo-karst collapse pillars in northern China, this paper also introduces the new methods of integrated prospecting of successive approximation to determine hydraulic conductivity of palaeo-karst collapse pillars.     

Conservation of natural and cultural heritage in Dunhuang,China

A country's natural and cultural heritage is created in a unique environment, and for this heritage to survive, it must be preserved in a similar environment. In China, 60 years of afforestation to combat desertification near the Mogao Grottoes and the Crescent Moon Spring have shown that attempts to protect the regional environment have not protected these heritage sites, and may actually have endangered them. Conserving the environment's original state may be the most effective solution for heritage conservation where sites have survived under a specific set of physical and environmental conditions for hundreds or thousands of years and may not be able to survive a new environment. Man-made changes should only be attempted with great care to avoid damaging the conditions that have preserved the natural or cultural heritage in the long term.     

Heavy metals and polychlorinated biphenyls in sediments of the Yangtze river estuary,China

Typical pollutants in sediments from 22 sampling sites of the Yangtze river estuary in 2006 were investigated in the present study. Arsenic, mercury, cadmium, copper, chromium, zinc, lead, and polychlorinated biphenyls of the Yangtze river estuary sediments were found as 6.49–17.6, 0.0164–0.0987, 0.059–0.319, 11.7–46.6, 10.5–113, 44.5–125, 14.8–32.7, and 0.0006–0.0026 mg/kg, respectively. Results indicated the presence of a contamination in the Yangtze river estuary. Through analyzing the contents of typical pollutants in sediments with adopting the index number techniques of Muller geoaccumulation index and Hakanson ecological risk factors and index, the quality status of these sediments were evaluated. Furthermore, the potential ecological risks of the estuary were determined quantitatively. The overall environmental quality of typical pollutants was generally in a good condition in most sites. The results showed that arsenic was the main environmental pollution factor, and cadmium was the main potential ecological factor. The highest potential ecological risk index appeared in the south branch of the Yangtze river, which was mainly due to terrestrial pollution in Shanghai. The results of this study can be used for decision makers to prioritize measures to control the pollution for these typical pollutants.     

干旱区土遗址病害的分类研究

我国西北干旱区分布大量的土遗址,在分析干旱区土遗址病害的基础上,建立了按病害成因、病害表现形式和形成机理分类的土遗址病害3级分类体系和定义。将土遗址的病害分为两大类即自然破坏和人为破坏。自然破坏有5个亚类14个病害表现形式,包括片状剥蚀:雨蚀剥离病害、风蚀剥离病害和裂隙剥离病害;淘蚀:酥碱、风力淘蚀和流水淘蚀;裂隙(缝):卸荷裂隙、构造缝、变形裂隙、建筑工艺裂缝;冲沟:裂隙型冲沟和径流型冲沟;生物破坏:动物病害和植物病害。人为破坏有两种即历史破坏和近现代破坏。     

Engineering characteristics and environmental impacts of the expansive Ankara Clay,and swelling maps for SW and central parts of the Ankara (Turkey) metropolitan area

Volume-changing clay soils constitute the most costly natural hazard to buildings on shallow foundations. With the existing expansive clays in Ankara, low-rise buildings at the southwest part of the city have shown damage resulting in considerable maintenance costs. This paper reports the findings of an experimental investigation emphasizing the swelling behavior of Ankara Clay and correlations between the swelling parameters and other soil properties, and present a synthesis of observed damage details. The poor performance of the affected light-weight structures is assessed in the light of environmental conditions. In addition, swelling maps for SW and central parts of the Ankara metropolitan area, based on measured and predicted swelling parameters, are constructed for the purposes of land-use planning and general assessment of environmental problems. The experimental results suggest that the clay has high-to-very high activity, depth of active zone generally ranges between 1–2 m, the use of remolded and desiccated specimens seems to be a better approach in swelling tests, and the empirical equations based on two or more index or physical properties are good predictors for the estimation of the swelling potential of the clay. High swelling pressures exerted by the soil, flat topography and poor drainage, climatic conditions and poor construction methods are the main reasons of the structural damage observed at the study site.     

Use of environmental magnetic techniques to monitor urban pollution origins in Lanzhou, Northwest China

In this study, samples of dustfall collected monthly or semi-monthly, during 1997–1999, at two representative sites (Kexueguan: KLD and Gaolanxan: GLX) in Lanzhou, a typical industrial city in northwestern China, have been examined using environmental magnetic measurements. A set of magnetic parameters of 50 dustfall samples were analysed. Results demonstrate that Lanzhou City is heavily polluted, with the main pollution sources being anthropogenic activities and natural dust. The former poses a threat to human health all the year, which is different from the general opinion that natural dust is the main source of pollution in summer. This study extended the application of environmental magnetic techniques and can be regarded as a progressive step in exploring urban pollution problems using environmental magnetic techniques. The results from the present study have an important implication on the design of future urban pollution control strategies in Lanzhou, and the method could be applied to other urban cities in the world.     

The Pulpí gigantic geode (Almería, Spain): geology, metal pollution, microclimatology, and conservation

The discovery of the giant Geode of Pulpí (Almería, Spain) was considered as an important highlight in the geological heritage of Spain. Projects developed for their conservation were immediately initiated with legal figures of protection and tourist projects. The Geode has a tourist interest, which must be tempered by environmental restrictions limiting the public visits. First results demonstrate that a continuous visit of two or three people for more than 10 min provokes the appearance of condensation and risks corrosion of the gypsum crystals. In addition, the electron microprobe analyses confirms (1) the hydrothermal phases of iron–manganese in carbonated host rock; (2) the presence of sulphides with Fe–Zn–Pb–Ag–Sb–Cu–Hg–As–Te–Se; and (3) Ba, Ca, and Sr sulphates with mercury traces. The present proposal to label the geode and the mining environment as geological-natural heritage is feasible, although any tourist adaptation must not permit visits to the geode indoor and Hg levels must be controlled.     

Meteorological factors affecting the speed of movement and related impacts of extratropical cyclones along the U.S. east coast

The speeds of historical cool-season extratropical cyclones along the U.S. east coast, hereafter East Coast Winter Storms (ECWS), occurring during the period from 1951 to 2006 were computed. Average storm speed was 13.8 ms⁻¹ with stronger storms generally moving faster than weaker storms and faster storms forming during the midwinter months (December–March). There was no clear trend in ECWS speed during the time period, although considerable season-to-season variability was present. The monthly and seasonal variations in storm speed could not be attributed to the El Ni?o-Southern Oscillation or North Atlantic Oscillation (NAO) alone. However, the speed of ECWS was considerably slower when both El Ni?o and the negative phase of NAO occurred simultaneously. Characteristic patterns in the upper levels of the atmosphere, specifically 300 hPa zonal winds and 500 hPa geopotential heights, were present during periods when ECWS speeds were among the slowest (and separately fastest). For slow storm speed, these patterns also prevailed during months in which El Ni?o and negative NAO phase occurred. These patterns were also present during months with extended runs of high oceanic storm surge. This provides a qualitative link between the atmospheric conditions associated with slow storms and potentially high coastal storm surge impacts. Among the prime consequences of ECWS speed are extended periods of high storm surge, mainly due to slow-moving storms. The sustained high tidal levels often lead to substantial damage caused by coastal flooding, overwash, and beach erosion.     

Windstorms in the United States

High winds are one of the nation’s leading damage-producing storm conditions. They do not include winds from tornadoes, winter storms, nor hurricanes, but are strong winds generated by deep low pressure centers, by thunderstorms, or by air flow over mountain ranges. The annual average property and crop losses in the United States from windstorms are $379 million and windstorms during 1959–1997 caused an average of 11 deaths each year. Windstorms range in size from a few hundred to hundreds of thousands square kilometers, being largest in the western United States where 40% of all storms exceed 135,000 km². In the eastern United States, windstorms occur at a given location, on average, 1.4 times a year, whereas in the western US point averages are 1.9. Midwestern states average between 15 and 20 wind storms annually; states in the east average between 10 and 25 storms per year; and West Coast states average 27–30 storms annually. Storms causing insured property losses >$379 million and windstorms during 1959–1997 caused an average of 11 deaths each year. Windstorms range in size from a few hundred to hundreds of thousands square kilometers, being largest in the western United States where 40% of all storms exceed 135,000 km². In the eastern United States, windstorms occur at a given location, on average, 1.4 times a year, whereas in the western US point averages are 1.9. Midwestern states average between 15 and 20 wind storms annually; states in the east average between 10 and 25 storms per year; and West Coast states average 27–30 storms annually. Storms causing insured property losses >1 million, labeled catastrophes, during 1952–2006 totaled 176, an annual average of 3.2. Catastrophic windstorm losses were highest in the West and Northwest climate regions, the only form of severe weather in the United States with maximum losses on the West Coast. Most western storms occurred in the winter, a result of Pacific lows, and California has had 31 windstorm catastrophes, more than any other state. The national temporal distribution of catastrophic windstorms during 1952–2006 has a flat trend, but their losses display a distinct upward trend with time, peaking during 1996–2006.     

硅酸钾材料加固土遗址耐风蚀颗粒元模拟分析

西北干旱地区土遗址受风化、风蚀等破坏严重,大量土质文物亟待加固抢修。加固后土遗址的各耐环境因素及加固机制研究是土遗址加固的理论基础。首次引入颗粒元程序PFC,通过改变模型中颗粒间平行连接强度,对硅酸钾（简称PS）加固前后的土样进行数值模拟。在考虑实际土样颗粒粒径和密度的前提下,拟合了生土PS加固前后的抗压和抗拉强度,并将拟合后的颗粒元模型应用于风蚀模拟。通过随机生成挟沙风颗粒,以一定的速度撞向土体,模拟挟沙风的吹蚀作用。挟沙风颗粒数与循环步数成正比例,因此,可以用挟沙风颗粒数来代表吹蚀时间的长短。挟沙风颗粒的速度则代表挟沙风风速。模拟结果表明,在20 m/s的挟沙风吹蚀作用下,风蚀程度随吹蚀时间的增加而增大,未加固土样的风蚀程度增幅度远大于加固土样;同样吹蚀时间条件下,加固土样的抗风蚀强度明显高于未加固土样。这些模拟结论与风洞试验结果的统计规律一致。本研究拟合的颗粒流模型可进一步应用于PS加固机制研究及耐风蚀、雨蚀、冻融等诸环境影响分析研究。     

RETRACTED ARTICLE: Space and time distributions of major winter storms in the United States

Winter storms are a major weather problem in the United States and their losses have been rapidly increasing. A total of 202 catastrophic winter storms involving ice storms, blizzards, and snowstorms, each causing >$5 million in damages, occurred during 1949–2003, and their losses totaled $35.2 billion (2003 dollars). Catastrophic winter storms occurred in most parts of the contiguous United States, but were concentrated in the eastern half of the nation where 88% of all storm losses occurred. They were most frequent in the Northeast climate district (95 storms), and were least frequent in the West district (14 catastrophic storms). The annual average number of storms is 3.7 with a 1-year high of nine storms, and one year had no storms. Temporal distributions of storms and their losses exhibited considerable spatial variability across the nation. For example, when storms were very frequent in the Northeast, they were infrequent elsewhere, a result of spatial differences in storm-producing weather conditions over time. The time distribution of the nation’s 202 storms during 1949–2003 had a sizable downward trend, whereas the nation’s storm losses had a major upward trend for the 55-year period. This increase over time in losses, given the decrease in storm incidences, was a result of significant temporal increases in storm sizes and storm intensities. Increases in storm intensities were small in the northern sections of the nation, but doubled across the southern two-thirds of the nation, reflecting a climatic shift in conditions producing intense winter storms.     

Environmental restoration measures on the Tennessee–Tombigbee Waterway – an update

 The Tennessee–Tombigbee Waterway (Tenn–Tom) was one of the first and largest water resources projects constructed after the enactment of the National Environmental Policy Act of 1969. This highly controversial project was in litigation for 9 of the 13 years it was under construction. Substantial and innovative measures were incorporated into the project design to minimize environmental damage and to promote environmental protection. Additionally, a wide variety of environmental mitigation measures, including the acquisition and management of 35,614 ha of wildlife habitat to compensate for unavoidable impacts. This paper, which updates a paper published by the American Society of Civil Engineers in 1996, presents an update of the environmental and restorative measures incorporated into the design, construction, operation, and management of the Tenn–Tom some 15 years after it was opened for navigation. The paper examines the accuracy of selected predicted impacts, waterway utilization, and the effectiveness of environmental measures. Received: 13 March 2000 · Accepted: 12 June 2000     

A Spatial and Temporal Analysis of Damaging Snowstorms in the United States

Records of very damaging snowstorms, those causing more than $25 million in property losses, across the United States were assessed to define the spatial and temporal dimensions of the nation’s snowstorm activity during 1949–2000. In this 52-year period 155 snowstorms occurred and caused losses totaling $21.6 billion (2000 dollars). The northeastern U.S. had the nation’s maximum storm occurrences (79 storms), total losses ($7.3 billion), and storm intensity. Two-thirds of all U.S. losses occurred in the Northeast, Southeast, and Central climate regions, and storm occurrences and losses were least in the western U.S. The incidence of storms peaked in the 1976–1985 period and exhibited no up or down trend during 1949–2000. However, national losses had a significant upward time trend, as did storm sizes and intensity. States with the greatest number of storms were New York (62) and Pennsylvania (58) with only 2 storms in Montana, Idaho, and Utah. Storm losses in the northeastern and southeastern U.S. had U-shaped time distributions with flat time trends for 1949–2000, but losses in the western regions and Deep South had distinct upward trends in losses and storm size. More than 90% of all storm losses in the western U.S. occurred after 1980. These findings indicating increased losses over time reflect that a rapidly growing population and vulnerability of more property at risk have been major factors affecting losses, and the lack of a change over time in snowstorm incidences suggests no change in climate during 1949–2000.     

PS加固土遗址土体的红外热像检测试验研究

红外热像技术作为一门新兴的无损检测技术,是基于被测对象温度场的变化规律而进行的,目前广泛应用于检测物体表面的结构状态、性质和内部缺陷等。为了探讨土遗址加固土体的无损检测方法,以新疆交河故城遗址现场采取的扰动土制作了模型。模型的1/2用浓度为10%PS（PS为一种高模数的硅酸钾溶液）加固,1/2不加固,将加固后的模型室温静置30 d,自然风干后进行了红外热像室内模型试验。试验表明,PS阻碍了土体的热传导过程,加固前后的土遗址土体在红外热像上会出现差异,为进行土遗址加固效果的无损检测提供了一种途径。最后进行了PS加固遗址土体的热传导率测定试验和微型贯入仪现场试验,结果表明加固土体与未加固土体的热传导性能产生差异的原因与经PS加固减小了土体的热传导率、提高了土体的力学强度有关     

西北干旱区石窟遗址保护

我国的石窟研究遗址主要分布于西北干旱区。由于独特的自然条件,风蚀风化作用强烈,大批遗址已破坏严重。因而开展石窟遗址防风化加固和岩体裂隙灌浆研究十分必要。钾水玻璃(PS)是一种水溶性的无机胶结加固材料,试验证明经PS-C材料加固后的岩体强度成倍增长,耐风蚀能力、耐水能力明显提高。论文全面详尽地总结了PS-C材料加固石窟遗址技术,认识到PS-C是西北干旱地区石窟遗址加固的一种有效材料,可达到较理想的加固效果。