Deformation in the Three Gorges Reservoir after the first impoundment determined by GPS measurements

Currently,theongoingThreeGorgesProject(TGP)isthebiggesthydraulicprojectintheworld andtheThreeGorgesdamwillbeoneofthehighest dams.Standing185mhigh,itwillbeholding3.92×1010m3ofwaterwhencompletedin2009.Howev er,previousresearchesandhistoricalrecordshave shownthatsuchahugecontentofwatermighttrig germinorandmediateearthquakes[1—4],becausea decreaseoffrictiononanactivefaultduetoporepres surediffusenessandenhancedwaterpermeationcould causefaultintermittentunlockingtoreleaseseismic energy[4,5—8]…     

Behavior of Plastic Concrete Diaphragm Walls in Three Gorges Project

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｅｃｏｎｄｓｔａｇｅｃｏｆｅｒｄａｍ，ｉｎｃｌｕｄｉｎｇｕｐｓｔｒｅａｍａｎｄｄｏｗｎｓｔｒｅａｍｃｏｆｅｒｄａｍｓ，ｉｓｏｎｅｏｆｔｈｅｋｅｙｓｔｒｕｃｔｕｒｅｉｎＴｈｒｅＧｏｒｇｅｓＰｒｏｊｅｃｔ．Ｔｈｅｃｏｆｅｒ...     

A Study of the Crustal Stability in the Yangtze Three Gorges Area

TheThree GorgesHydroelectricPow erProjectontheYangtzeRiverwillstorewaterandgenerateelectricpowerin 2 0 0 3.Itsgreatdamwasdesignedtobe 1 85mhigh ,withaninstallingcapa bilitytobe 1 7.6 8millionkWh ,andatotalreservoirstoragetobe 39 3billionm3 .ThisisanimportantmatterinChina seconomicconstructionandalsoamonumentalprojectinChinesehistory(Fig 1 ) [1 ] .Thus,thecrustalstabilityforthegreatdamhasattractedmuchat tention .Theauthorshadcarriedoutfieldinvestigationanddemonstratedthefeasibilityoftheeng…     

Relation between human existence and environment viewing from the distribution of prehistoric archaeological sites in the Three Gorges reservoir region of the Yangtze River,China

Based on archaeological research findings in the Three Gorges region as well as the distribution of prehistoric sites in this area,the following conclusion can be derived:the unique physical and geographical conditions and variations in the Three Gorges region make local people of different ages seek their survival and development in the favorable environment along the riverbanks.Environment evolution has direct impact on the selection of location for survival.The increase of sites quantity reflects the favorable natural environment,but the decrease just reflects the consequence of such natural disasters as flood.     

Partial continuation model and its application in mitigating systematic errors of double-differenced GPS measurements

Based on the so-called partial continuation model with exact finite measurements, a new stochastic assessment procedure is introduced. For every satellite pair, the temporal correlation coefficient is estimated using the original double-differenced (DD) GPS measurements. And then, the Durbin-Watson test is applied to test specific hypothesis on the temporal correlation coefficient. Unless the test is not significant with a certain significant level, a data transformation is required. These transformed measurements are free of time correlations. For purpose of illustration, two static GPS baseline data sets are analyzed in detail. The experimental results demonstrate that the proposed procedure can mitigate effectively the impact of systematic errors on DD GPS measurements.     

Application of adaptive filtering by selecting the parameter weight factor in precise kinematic GPS positioning

A new method of adaptive filtering by selecting the parameter weight factor is introduced in this paper. Based on the theoretical analysis and research, this method is firstly used for precise kinematic GPS positioning with single frequency double-differenced (DD) carrier phase observations. Two numerical examples are given to illustrate the feasibility and validity of the method. The preliminary results show that precise positioning results can be obtained by using only the GPS single frequency DD carrier phase measurements for short baselines with the new method.     

Numerical simulation of topography effects on the “00.7” severe rainfall in Beijing

In an effort to study the severe rainfall event of 4?5th July 2000 in Beijing (with 24h accumulated precipitation of 240 mm), we perform numerical simulations to investigate this event using the MM5v3.6 model. The model is initialized with the MM5/WRF 3DVAR analysis, which incorporates the ground-based GPS precipitable water vapor, automatic and conventional meteorological observations in its assimilation step. For 24 h accumulated precipitation forecast, the threat scores are 0.72, 0.76, 0.67 and 0.63, for thresholds of 1, 5, 10, and 20 mm, respectively. Holding other factors unchanged, sensitivity experiments were conducted with different topographic resolutions of 110, 50 and 3.7 km to investigate the topographic effects on precipitation over the Beijing area. In these sensitivity experiments, we attempt to preserve the realistic orographic distribution in the model topography under the condition of keeping the dynamic-thermodynamic consistency of the initial model atmosphere to the extent possible. Results indicate that the unique topographic distribution and variations in the Beijing area play an important role in determining the location, distribution and intensity of heavy precipitation.     

Petrological implication of wagnerite-Ma5bc in the quartzofeldspathic gneiss, Larsemann Hills, East Antarctica

Wagnerite-Ma5bc polytype is found in a gneiss associated with cordierite-prismatine-bearing gneiss, northern Stornes Peninsula, Larsemann Hills, East Antarctica. Wagnerite coexists with apatite and both of them are present as rock-forming minerals. Ca depletion is not essential to the formation of wagnerite; sufficient Mg, P and F components, and a relatively low CaMg ratio is critical, otherwise only apatite crystallizes. Strong anatexis of the quartzofeldspathic gneiss of the area results in differentiation and separate enrichment of leuco- and melanocratic components. P and F tend to accumulate in the mafic-rich melanocratic component, and when their abundance reaches certain concentration, wagnerite forms. It is perhaps the chemistry of the setting that controls the appearance of wagnerite, whereas the PT condition is responsible for the variety of wagnerite polytype. A disordered polytype crystallizes at relatively high temperature, then cools down slowly and transforms into one of the ordered polytypes, in this case, the Ma5bc polytype.