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1.
With lots of indoor and outdoor experiments, several key technical issues in construc-tion of the Desert Highway have been solved satisfactorily, on the basis of great achievements ofthe studies in respects of dry compaction on sand base, design parameters, structure combinationof subgrade and pavement, stabilization analysis of sand base strengthened with geotextile and acomplete set of construction techniques. It is the first time the achievements of the study weresuccessfully applied in the Taklimakan Desert where the natural condition is extremely harsh. Ithas been proved that it is economic and reasonable with reliable techniques and simple construc-tion methods. The Desert Highway constructed with the achievements is the first-grade highwayrunning through huge migratory desert for long distance in the world. 相似文献
2.
The Tarim Desert Highway in Xinjiang, China, the longest one in the world, has a length of 562 km, about 80% of which runs across, from north to south, the Taklimakan Desert. Obviously, the main problem of the road maintenance is the blown sand disaster. The research results showed: (1) the physical environment along the desert highway is characterized by strong winds, fine and loose ground materials, different dunes and so on, which provides the dynamical condition and material source for the formation of blown sand disaster to the road and its shelter system. Meanwhile, the trend and cross-section of the road and the structure of the shelter system, as damage objects, play important roles in the formation process of blown sand disaster; (2) the blown sand disaster to the shelter system is original from the intrusion of the drift sands and mobile dunes outside the shelter system, and the wind erosion and sand deposit caused by the air stream changes on the ground in the shelter system. The main damage object in the Tarim Desert Highway is the shelter system presently. The damage forms include wind erosion, sand burying and dune covering; and (3) the damaged length of the blocking sand fences is 83.7%, 88.4%, 72.4%, 72.8% and 40.3% and the damaged area of the straw checkerboard belts is 73.1%, 58.2%, 44.5%, 35.4% and 36.6%, in turn, in 5 different landform units from north to south, and, the disasters to fences and the straw checkerboard belts are 79.5% and 57.6% in the compound dunes while they are 64.6% and 37.7% in the interdunes respectively.
相似文献3.
The Tarim Desert Highway in Xinjiang, China, the longest one in the world, has a lengthof 562 km, about 80% of which runs across, from north to south, the Taklimakan Desert. Obviously,the main problem of the road maintenance is the blown sand disaster. The research resultsshowed: (1) the physical environment along thedesert highway is characterized by strong winds,fine and loose ground materials, different dunes and so on, which provides the dynamical conditionand material source for the formation of blown sand disaster to the road and its shelter system.Meanwhile, the trend and cross-section of the road and the structure of the shelter system, asdamage objects, play important roles in the formation process of blown sand disaster; (2) theblown sand disaster to the shelter system is original from the intrusion of the drift sands and mobiledunes outside the shelter system, and the wind erosion and sand deposit caused by the air streamchanges on the ground in the shelter system. The main damage object in the Tarim Desert High-way is the shelter system presently. The damage forms include wind erosion, sand burying anddune covering; and (3) the damaged length of the blocking sand fences is 83.7%, 88.4%, 72.4%,72.8% and 40.3% and the damaged area of the straw checkerboard belts is 73.1%, 58.2%, 44.5%,35.4% and 36.6%, in turn, in 5 different landform units from north to south, and, the disasters tofences and the straw checkerboard belts are 79.5% and 57.6% in the compound dunes while theyare 64.6% and 37.7% in the interdunes respectively. 相似文献
4.
Qu JianJun Zhang KeCun Sun Bo Jiang ShengXiang Dong GuangRong Zu RuiPing Fang HaiYan 《中国科学D辑(英文版)》2007,50(9):1351-1358
The sound-producing mechanism of booming sand has long been a pending problem in the blown sand physics. Based on the earlier researches, the authors collected some silent sand samples from Teng- ger Desert, Australian Desert, Kuwait Desert, beaches of Hainan Island and Japanese coast as well as the soundless booming sand samples from the Mingsha Mountain in Dunhuang to make washing ex- periments. In the meantime the chemical corrosion experiment of glass micro-spheres, surface coating experiment and SEM examination were also conducted. The experimental results show that the sound production of booming sand seems to have nothing to do with the presence of SiO2 gel on the surface of sand grains and unrelated to the surface chemical composition of sand grains but is related to the resonance cavities formed by porous (pit-like) physical structure resulting from a number of factors such as wind erosion, water erosion, chemical corrosion and SiO2 gel deposition, etc. Its resonance mechanism is similar to that of Hemholz resonance cavity. Under the action of external forces, nu- merous spherical and sand grains with smooth surface and porous surface are set in motion and rub with each other to produce extremely weak vibration sound and then become audible sound by human ears through the magnification of surface cavity resonance. However the booming sands may lose their resonance mechanism and become silent sand due to the damping action caused by the invasion of finer particles such as dust and clay into surface holes of sand grains. Therefore, clearing away fine pollutants on the quartz grain surface is an effective way to make silent sand emit audible sound. 相似文献
5.
Observations of several characteristics of aeolian sand movement in the Taklimakan Desert 总被引：2，自引：0，他引：2
HAN Zhiwen DONG Zhibao WANG Tao CHEN Guangting YAN Changzhen & YAO ZhengyiKey Laboratory of Desert Desertification Cold Arid Regions Environmental Engineering Research Institute Chinese Academy of Sciences Lanzhou China Correspondence should be addressed to Han Zhiwen 《中国科学D辑(英文版)》2004,47(1):86-96
With both sides of the Taklimakan Desert highway line as the study area, three typical aeolian sand landforms, i.e. complex dune ridge, barchan dune and flat sand land, were selected as sand beds for the observation, analysis and research of the characteristics of aeolian sand movement such as aeolian sand stream structure, sand transport intensity, etc. in the Taklimakan Desert. The results show that there is a linear relation between the height and the log of sand transport rate over transverse dune chain, longitudinal dune ridge and flat sand land, i.e. the sand transport percentage decreases exponentially with increasing height. Sand transport rate within the 10 cm height above the bed surface accounts for 80%-95% of the total sand transport rate of the observed height (40 cm), while the sand transport rate in 20 cm occupies 98% of the total amount. Sand transport rate (g·cm-1·min-1) differs greatly with respect to different landform types and different topographic positions. Based on the investig 相似文献
6.
Controlling desertification is an important ecological target for the Qinghai-Tibet Plateau of China, where studies on impacts of vegetation restoration measures on sandy soil improvement are still lacking. The Mugetan Desert in Guinan County, Qinghai Province, northeastern Qinghai-Tibet Plateau is a repre-sentative ecological restoration area. The impacts of artificial vegetation on the ecological restoration and its properties are studied by using field investigation and sample testing including contents of the surface layer and the vegetation composition of movable, semi-fixed, and fixed sand dunes. Results demonstrate that the moss crust has formed on the surface of a sand dune which has become fixed after 30 years under the impact of artificial vegetation (i.e. Cathay poplar). Meanwhile, the clay minerals, organic matter, and other soil available nutrients have markedly increased. A correlation has been found between these materials, i.e., clay minerals and organic matter content increasing with silt and clay increases with reduction in sand content. In addition, soil nutrient were positively correlated with the increase of plant diversity.Under the current meteorological conditions, the artificial vegetation is helpful for the stabili-zation of sand dune and the ecological restoration in the Mugetan Desert. 相似文献
7.
Zhong He Jie Zhou ZhongPing Lai LinHai Yang JianMin Liang Hao Long XianJiao Ou 《Quaternary Geochronology》2010,5(2-3):102-106
The Mu Us Desert, located in the northwestern fringe of the East Asian monsoon region, is sensitive to climate variability. The desert is characterized by mobile, semi-fixed and fixed sand dunes. Alternating units of dune sands and sandy palaeosols in the Mu Us Desert imply multiple episodes of dune building and stabilization, in response to the ebb and flow of the East Asian monsoon. Desert evolution and climatic change of high-resolution in the Mu Us Desert are still poorly understood due to limited numerical dating results. In the present study, 19 samples collected from five sand dune sections along a northwest–southeast transect in the Mu Us Desert were dated using quartz optically stimulated luminescence (OSL) and single aliquot regenerative-dose (SAR) protocol. Internal checks of the OSL dating indicate that the SAR protocol is appropriate for equivalent dose (De) determination for the samples under study. Combined with the lithologic stratigraphy and the luminescence chronology, the sand dune development in the Mu Us Desert during the Late Pleistocene is discussed. Our results indicate that the sand was mobilized approximately at 91 ka, 71 ka, 48–22 ka, 5 ka, 1 ka, and 0.44 ka; the sand was fixed approximately at 65 ka and Holocene Optimum period in the interior Mu Us Desert. The Mu Us Desert formed at least before ～144 ka, and has shown increasing aridity in the Late Pleistocene. 相似文献
8.
David M. Rubin 《地球表面变化过程与地形》1990,15(1):1-14
Linear dunes in the Strzelecki Desert trend roughly south-north. Sand transport, which is toward the NNE, has caused the dunes to migrate eastward while they extend or migrate northward. Eastward lateral migration is evidenced by: (1) asymmetrical shape of the dunes; east-facing slopes are several times as steep as west-facing slopes; (2) asymmetrical accumulation of loose recently transported sand (relatively abundant on east-facing slopes); (3) asymmetrical outcropping of older semiconsolidated aeolian sand on the dune surface (more abundant on west-facing slopes); and (4) east-dipping foreset beds that underly the west-facing flanks of some dunes. Dunes in the Strzelecki Desert are still active in the sense that sand is transported along and across many dune crests. However, the dunes are composed primarily of Pleistocene strata, indicating that the trend of the dunes was established before the Holocene. The obliquity of the dunes to the transport direction is not merely an aberration of the wind regime of the last few decades. Preferential accumulation of sand on east-facing flanks indicates that the dunes migrated eastward several metres during the Holocene. Moreover, the west-facing flanks of some dunes have experienced a minimum of tens of metres of erosion. This asymmetric erosion and deposition were caused by dune obliquity and lateral migration that may have begun as early as the Pleistocene. Dunes in the Strzelecki Desert and in the adjacent Simpson Desert display a variety of grossly different internal structures. Computer graphics experiments demonstrate that many of these differences in structure can be explained by different angles of climb of the dunes. 相似文献
9.
Monitoring surface change on a Namib linear dune 总被引：1，自引：0，他引：1
Ian Livingstone 《地球表面变化过程与地形》1989,14(4):317-332
In tackling the apparently intractable problem of linear dune initiation and maintenance there has been a move away from large-scale deductive models to smaller-scale field studies of individual dunes. This paper reports a study of surface change on a large, complex linear dune in the Namib Desert, southern Africa. The dune surface responds to a markedly seasonal wind regime. In summer westerly winds erode sand from the west flank of the dune and deposit it on the easterly lee side of the dune crest. In winter this pattern is reversed. Easterly winds erode sand from the east slope and deposit it on the west slope. The crest therefore moves back and forth some 15 m each year returning at the end of a year's cycle to its position at the beginning. The position of the base of the dune appears to remain fixed, even though sand is moving throughout the dune system. The dune does extend northward along some resultant of the westerly and easterly winds. Despite relatively high levels of activity, especially at the dune crest, there is no evidence of the breakdown of the linear dune form. The conclusion must therefore be that linear dunes can be maintained in bimodal wind regimes and are not necessarily related to unidirectional parallel regimes as others have suggested. 相似文献
10.
Signs of the evolutionary process are well preserved in the aeolian deposits of desert margins and enable reconstruction of desert expansion and contraction. The sand content (percentage >63 µm) of loess in the loess–desert transitional zone was used as a proxy indicator for determining the proximity of the desert margin. According to the dominant wind direction, generally NW–SE in the northwest Chinese Loess Plateau, a transect was projected to observe spatial changes in sedimentological characteristics of aeolian deposits during the Last Glacial Period. The transect consists of 12 loess sections, starting at Shapotou in the transitional region between the Loess Plateau and the Tengger Desert and ending at Tianshui, which is located at the north foot of the Western Qinling Mountains in the southernmost part of the Loess Plateau. It shows the properties of temporal and spatial distribution of the Malan loess, with reduced sand content from northwest to southeast. A linear correlation model of sand content and distance was obtained, which was similar to the east of the Chinese Loess Plateau. According to this model, and on the basis of optically stimulated luminescence (OSL) dating from Binggou section, a detailed and quantificational expansion and contraction for the Tengger Desert was established. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
11.
The longitudinal dunes of the Simpson Desert, in the vicinity of Birdsville, have been reworked largely during the Holocene from dunes deposited up to 80000 years ago or earlier. The widespread asymmetry of these roughly northward-trending dunes, with steeper eastern faces and more gentle western faces, supports wind-rose data showing sand-transporting winds from the southwest obliquely intersecting the dunes. While this suggests a change in the wind pattern since the dune field was oriented, it does not indicate that the dunes are necessarily shifting leeward (eastward) as a consequence. It is hypothesized that the direction of migration is controlled by the extent to which the dunes are vegetated. Relatively well-vegetated dunes can accrete sand on their gentle stoss slopes and erode on their lee slopes causing them to shift westward and hence obliquely into the wind, a condition that probably prevails in wetter regions and during episodes of relatively humid climate. In contrast, in very dry areas or during arid phases, sand can move unimpeded up a sparsely vegetated stoss face and over the crest to form an avalanche or slip face on the lee side, thereby causing the dunes to shift eastward. Despite evidence that longitudinal dune crests can shift laterally to some extent, the dunes in the western part of the Simpson Desert have not migrated, either westward or eastward, more than 100m or so from their Pleistocene cores. Aeolian transport and partial or complete removal of iron cutans from around quartz grains results in dunes of widely varying colour yet of similar age. 相似文献
12.
Longitudinal dunes are the most widespread dune types in the world sand seas but comprehensive study on the sand surface stability
is scarce. The southern part of Gürbantünggüt Desert is mainly covered by longitudinal dune in which fixed and semi-fixed
dunes occupy over 80% of the total area. Systematic analysis on the climatic conditions, the soil moisture and vegetation
distributions, and the sand surface activities showed that the fixed and semi-fixed dunes are in a comprehensive low-energy
wind environment. Snow cover and frozen soil provide a good protection to the ground surface in winter. The temporal distribution
of precipitation and corresponding variation of temperature create a favorable condition for the desert plants growth, especially
for the ephemeral plants. The occurrence of effective winds for sand moving in April to June coincides with the stage of relatively
wet sand surface and good vegetation cover, which effectively keep the sand surface stable at the interdune and the plinth
of the dunes. Activity sand surface appears only at the crest and the upper part of the sand dunes. 相似文献
13.
D. Hülle A. Hilgers U. Radtke C. Stolz N. Hempelmann J. Grunert T. Felauer F. Lehmkuhl 《Quaternary Geochronology》2010,5(2-3):107-113
The present study focuses on the chronological relationship between alternating dune sand and silty water-lain sediments in the central part of the Khongoryn Els dune field in the Gobi Desert, Southern Mongolia. The 23 m high section evolved from the construction of a natural dam by west–east moving sand dunes and fluvial inundation by a river system from the mountain ranges in the south. To resolve the chronology of events, optically stimulated luminescence (OSL) dating was applied and from sedimentological and geochemical analysis the depositional processes could be characterised. Quartz OSL dating of these sediments is hindered by feldspar contamination. Thus, dating of coarse-grain K-feldspars is applied to provide a more reliable chronostratigraphy. As this fraction might be influenced by signal loss over geological time scales, the extent of fading is measured and corrected for. The resulting ages fit well in a supraregional reconstruction of Central Asian palaeoclimate. The data imply that the basal aeolian sediments were deposited 27 ka ago, while the major part of the profile was accumulated in a rather short period of time around ～15 ka. The temporal differentiation implies that the stratification of aeolian and fluvial sediments is not caused by long term climatic variations. It rather represents arid conditions with episodical fluvial activity. Samples between 20 and 15 m depth could not be taken, but it is assumed that this part of the section represents an extremely arid time period with an intensive remobilisation of sand around LGM. A dune overlying the section was deposited during the Late Holocene and represents the ongoing aridity in this region. 相似文献
14.
Liquefaction mitigation in silty soils using composite stone columns and dynamic compaction 总被引：2，自引：1，他引：1
T.Shenthan R.Nashed S.Thevanayagam G.R.Martin 《地震工程与工程振动(英文版)》2004,3(1):39-50
The objective of this study is to develop an analytical methodology to evaluate the effectiveness ofvibro stone column (S. C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and mitigate liquethctionin saturated sands and non-plastic silty soils. It includes the following: (i) develop numerical models to simulate and analyze soil densification during S.C. installation and D.C. process, and (ii) identify parameters controlling post-improvement soil density in both cases, and (iii) develop design guidelines for densification of silty soils using the above techniques. An analytical procedure was developed and used to simulate soil response during S.C. and D.C. installations, and the results were compared with available case history data. Important construction design parameters and soil properties that affect the effectiveness of these techniques, and construction design choices suitable for sands and non-plastic silty soils were identified. The methodology is expected to advance the use of S.C. and DC. in silty soils reducing the reliance on expensive field trials as a design tool. The ultimate outcome of this research will be design charts and design guidelines for using composite stone columns and composite dynamic compaction techniques in liquefaction mitigation of saturated silty soils. 相似文献
15.
Do biological soil crusts determine vegetation changes in sandy deserts? Implications for managing artificial vegetation 总被引：2，自引：0，他引：2
Biological soil crusts (BSCs), which are widespread in arid and semiarid regions, such as sandy deserts, strongly influence terrestrial ecosystems. Once sand‐binding vegetation has been established on sand dunes, BSCs are colonized and gradually develop from cyanobacteria dominated crusts to lichen and moss dominated crusts on dune surfaces. We conducted this study to determine if the occurrence and development of BSCs in the Tengger Desert could be used to determine sand‐binding vegetation changes via altering soil moisture and water cycling using long‐term monitoring data and field experimental observation. BSCs changed the spatiotemporal pattern of soil moisture and re‐allocation by decreasing rainfall infiltration, increasing topsoil water‐holding capacity and altering evaporation. Changes in the soil moisture pattern induced shifting of sand‐binding vegetation from xerophytic shrub communities with higher coverage (35%) to complex communities dominated by shallow‐rooted herbaceous species with low shrub coverage (9%). These results imply that BSCs can be a major factor controlling floristic and structural changes in sand‐binding vegetation and suggest that the hydrological effects of BSCs must be considered when implementing large‐scale revegetation projects in sandy deserts. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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17.
Palaeomonsoon variability in the southern fringe of the Badain Jaran Desert,China, since 130 ka BP 总被引：1，自引：0，他引：1
Quanzhou Gao Zhen Tao Baosheng Li Heling Jin Xueyong Zou Yechun Zhang Guangrong Dong 《地球表面变化过程与地形》2006,31(3):265-283
Taking the Chagelebulu Stratigraphic Profile as a typical example, a comprehensive study has been conducted to elucidate the palaeoclimatic and geomorphic evolution patterns in the southern fringe of the Badain Jaran Desert, which were found to be complex and polycyclic in the past 130 ka. However, the fluctuating magnitude is not as remarkable as that in the eastern China sandy region. The shift in climate from interglacial to glacial and the uplift process of the Qinghai–Xizang Plateau are the two leading forces driving the evolution of the climate and desert landforms in this area. Seventeen cycles of cold, dry and warm, humid climatic stages were recognized in the Upper Pleistocene Series of the profile. The sharp uplift of the Qinghai–Xizang Plateau superimposed a cool and arid climatic trend in this area. As a result of the climatic changes, the desert in this area has undergone multiple stages of expansion and contraction since 130 ka bp . The middle Holocene Epoch and the early stage of the Late Pleistocene Period were the main periods when the sand dunes became stabilized, and the early and late phases of the Holocene Epoch and late phase of the Pleistocene Epoch were the main periods when the previously stabilized sand dunes became mobile. The late phase of the Pleistocene Epoch was the most mobile stage, when the aeolian sand activities formed the essential geomorphic pattern of the Badain Jaran Desert. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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19.
N. Lancaster 《地球表面变化过程与地形》1984,9(5):469-478
Small scale features resulting from wind erosion are widespread in the Namib Desert. They include selective erosion of lithological variations (etching), flutes and grooves, facetting of clasts and residual boulders, and smoothing and polishing of rock surfaces. Large scale features are tentatively identified and are restricted to the southern Namib, with its high energy, unidirectional wind regime. Wind erosion features are best developed on fine-grained rocks of intermediate hardness. They are oriented towards or parallel to modern strong winds. The turbulent flow of wind armed only with dust particles is probably more important than wind driven sand in creating smooth polished rock surfaces, flutes, and grooves. Wind driven sand appears to be significant only in facetting rock masses. 相似文献
20.
Influence of subaqueous processes on the construction and accumulation of an aeolian sand sheet 
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下载免费PDF全文 In aeolian sand sheets the interaction between aeolian and subaqueous processes is considered one of the principal factors that controls this depositional environment. To examine the role played by the subaqueous processes on the construction and accumulation of sand sheets, surface deposits and subsurface sedimentary sections of a currently active aeolian sand sheet, located in the Upper Tulum Valley (Argentina), have been examined. On the sand sheet surface, airflows enable the construction of nabkhas, wind‐rippled mantles (flattened accumulations of sand forming wind ripples), megaripples, and small transverse dunes. Subaqueous deposits consist of sandy current ripples covered by muddy laminae. The latter are generated by annual widespread but low‐energy floods that emanate from the nearby mountains in the aftermath of episodes of heavy precipitations. Deposits of subaqueous origin constitute 5% of the accumulated sand sheet thickness. The construction of the sand sheet is controlled by meteorological seasonal changes: the source area, the San Juan river alluvial fan, receives sediment by thaw‐waters in spring–summer; in fall–winter, when the water table lowers in the alluvial fan, the sediment is available for aeolian transport and construction of the sand sheet area. The flood events play an important role in enabling sand sheet accumulation: the muddy laminae serve to protect the underlying deposits from aeolian winnowing. Incipient cement of gypsum on the sand and vegetation cover acts as an additional stabilizing agent that promotes accumulation. Episodic and alternating events of erosion and sedimentation are considered the main reason for the absence of soils and palaeosols. Results from this study have enabled the development of a generic model with which to account for: (i) the influence of contemporaneous subaqueous processes on the construction and accumulation in recent and ancient sand sheets; and (ii) the absence of developed soils in this unstable topographic surface. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献