基于土壤侵蚀遥感调查的河流输沙量的计算

河流泥沙来量的计算是工程水文计算的一个重要组成部分。有水文站观测资料的地方,输潲星的计算比较容易。而对于没有水文站分布或观测资料不足的边远地区,用常规无法计算出输沙星。     

夯扩桩沉管控制贯入度计算法

通过改造格尔谢万诺夫打桩公式,提供了夯扩桩沉管控制贯入度计算表达式,在此 ,介绍了沉积控制贯入度在夯扩桩设计和施工中的用途,并举例验证。     

Mobility of Al, Co, Cr, Cu, Fe, Mn, Ni and V in sulphide-bearing fine-grained sediments exposed to atmospheric O2: an experimental study

 The major aim was to increase our knowledge on the behaviour of Al, Co, Cr, Cu, Fe, Mn, Ni and V in sulphide-bearing fine-grained sediments exposed to atmospheric oxygen. Samples of this type of sediment collected in a previous investigation at eight sites in western Finland were digested in HClO₄-HNO₃-HCl-HF at 200  °C and in HCl:HNO₃:H₂O at 95  °C (aqua regia), and subjected to extractions with ammonium acetate and hydrogen peroxide. Metals and S in the leachates were determined with ICP-AES. The results of the chemical analyses are compared with previously reported experimental data. The concentrations of Al and Fe in the sulphide-bearing fine-grained sediments are about 7% and 5%, respectively. Of the trace metals studied, Mn is most abundant followed in decreasing order by V>Cr>Ni>Cu>Co. On oxidation of the sediments, high proportions of Co, Mn and Ni, intermediate proportions of Cu but low proportions of Fe, Al, Cr and V are released. The extent of the release of a metal on oxidation is controlled either by (1) the level to which the pH of the sediments drops on oxidation (Al, Cu, Cr, V), (2) the amount of the metal associated with easily reduced phases (metal sulphides) in the sediments (Ni, Co) or (3) the sum of the amount associated with reduced phases and adsorbed on soil compounds (Mn). No control of the release of Fe on oxidation of the sediments was identified. Based on the results of the study it is argued that artificial drainage and the subsequent oxidation of sulphide-bearing sediments will result in extensive leaching of Co, Mn and Ni, moderate leaching of Cu and limited leaching of Cr and V into drainages. The major elements, Fe and Al, have the potential to be mobilised and leached in large amounts, though the proportions mobilised/leached will remain low. It is suggested that the identification of sulphide-bearing sediments with a high potential of metal release should be based on determination of metals in easily mobilised reduced compounds (dissolved e.g. in H₂O₂) and of the level to which the pH of the sediments drops on oxidation. Received: 16 October 1997 · Accepted: 9 March 1998     

The recent history of erosion and sedimentation on the Southern Tablelands of southeastern Australia: sediment flux dominated by channel incision

As in other regions colonised from Europe within the last few centuries, Australia's vegetation and soils have been dramatically changed by clearing, cropping and grazing. In southeastern Australia, particularly on the Southern Tablelands, the impacts of European settlement are clearly manifested by channel incision. By using stratigraphic and documentary evidence, in conjunction with aerial photographs, sediment budgets for the post-settlement period have been constructed to define the fluxes and stores of sediment for each of the major geomorphic components of the 136 km² catchment of Jerrabomberra Creek near Canberra. Using these budgets, and some plausible assumptions, it has been possible to approximate the history of both the sediment delivery ratio and sediment yield for this catchment. While the quantities estimated in this analysis are approximations, the trends through time are credible. Sediment yield increased rapidly to a peak after European settlement, and has returned to a level between the peak and the pre-European value. The delivery ratio has followed a similar trend. The most general conclusion to emerge is that in this landscape both the total sediment flux and the sediment yield of the catchment have been dominated by channel erosion. This result is contrary to the findings in many parts of the world where sheet and rill erosion dominates the fluxes. The soil conservation implication of these results is clear: to control off-site effects of erosion, the focus must be on the channels.     

Holocene sedimentation in Lake Winnipeg, Manitoba, Canada: implications of compositional and textural variations

Two seismic facies were recognized in the sedimentary sequence overlying acoustic basement in Lake Winnipeg. The upper facies, which overlies a regional unconformity, is termed the Lake Winnipeg Sequence. Based on the seismostratigraphy, lithostratigraphy, and radiocarbon dates of approximately 4000 and 7000 yr BP from material collected directly over the unconformity in the southern and northern parts of the lake, respectively, this facies has been interpreted as representing Holocene sedimentation. Results of compositional and textural analyses of the Holocene sediment (Winnipeg sediment) from thirteen long (>2 m) cores indicate a transgressional sequence throughout the basin. In the South Basin, the generally fining upward sequence is characterized at the base by silt-sized detrital carbonate minerals, quartz and feldspar which decrease in concentration upward. In this basin, the high carbonate content and V/Al and Zn/Al ratios are indicative of a Paleozoic and Cretaceous provenance for sediment derived from glacial deposits through shoreline erosion and fluvial transport, via the Red River. Sedimentation in the central part of the lake and the North Basin is attributed to shoreline erosion of sand and gravel beaches. Consequently, the texture of these sediments is generally coarser than in the South Basin, and the composition primarily reflects a Paleozoic and Precambrian provenance. The basin-wide decrease in Ca, total carbonate minerals, dolomite and calcite concentrations upward in the cores is reflected by a decrease in the detrital carbonate component in all but the most northern cores. Other basin-wide trends show an upward increase in organic content in all cores. An increase in grain size near the top of most cores suggests a major, basin-wide change in sedimentation within the last, approximately 900 years in the South Basin.     

ON THE SELF ORGANIZED CRITICALITY OF NON UNIFORM SANDS

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Relationship between faults and generation of inland shallow earthquakes: enlightenment of the M=7.2 southern Hyogo prefecture earthquake

The M=7.2 southern Hyogo prefecture earthquake, which occurred on January 17, 1995, destroyed the region severely. Further researches are necessary to explain the problems obtained from this earthquake. We have discussed some characteristics correlating with this earthquake, such as distribution of aftershocks and disaster, relationship between fault and generation of inland shallow earthquakes, strong motion and so on. The tectonic movements of surface faults may be different from those of deep faults. Earthquakes may not be restricted directly by the tectonic movements of surface faults. The strong motion zone is often appeared in the region a little away from the both ends or from the single side of a fault instead of the region of a focal fault. Some mechanisms of strong motion have also been discussed.     

PREDICTING RESERVOIR SEDIMENTATION WITH 2D MODEL FLOODSIM

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覆盖开关在水中地震折射波法中的运用

介绍了浅层地震折射波法在铁路桥基础勘查中的应用。使用覆盖开关,采用互换法,提高了野外数据采集速度,降低了成本。     

Tectonic elements controlling the evolution of the Gulf of Saros (northeastern Aegean Sea, Turkey)

Tectonic elements controlling the evolution of the Gulf of Saros have been studied based upon the high-resolution shallow seismic data integrated with the geological field observations. Evolution of the Gulf of Saros started in the Middle to Late Miocene due to the NW–SE compression caused by the counterclockwise movement of the Thrace and Biga peninsulas along the Thrace Fault Zone. Hence, the North Anatolian Fault Zone is not an active structural element responsible for the starting of the evolution of the Gulf of Saros. The compression caused by the rotational movement was compensated by tectonic escape along the pre-existing Ganos Fault System. Two most significant controllers of this deformation are the sinistral Ganos Fault and the dextral northern Saros Fault Zone both extending along the Gulf of Saros. The most important evidences of this movement are the left- and right-oriented shear deformations, which are correlated with structural elements, observed on the land and on the high-resolution shallow seismic records at the sea. Another important line of evidence supporting the evolution of this deformation is that the transgression started in the early-Late Miocene and turned, as a result of regional uplift, into a regression on the Gelibolu Peninsula during the Turolian and in the north of the Saros Trough during the Early Pliocene. The deformation on the Gelibolu Peninsula continued effectively until the Pleistocene. Taking into account the fact that this deformation affected the Late Pleistocene units of the Marmara Formation, the graben formation of the Gulf of Saros is interpreted as a Recent event. However, at least a small amount of compression on the Gelibolu Peninsula is observed. It is also evident that compression ceased at the northern shelf area of the Gulf of Saros.