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141.
There could be some discontinuities in a soil media such as layers, earth structures, cracks, and fissures so that estimation
of stresses and deformations in these types of soil masses are somewhat different from continuous masses. The discontinuities
in a soil mass could be considered as a special link between two blocks. Transmitted swelling pressures affected by the soil
properties of the backfill especially at the interface between the backfill and retaining wall. In order to estimate the transmitted
swelling pressure distribution behind a retaining wall, using with interface element, a new finite element model and a code
(SWELPRES) have been developed. To evaluate the effect of backfill characteristics and interface element from the transmitted
lateral swelling pressures, four cases of thickness of backfills with or without interface elements are investigated. 相似文献
142.
Eduardo E. Alonso Sarah M. Springman Charles W. W. Ng 《Geotechnical and Geological Engineering》2008,26(6):817-826
Two large-scale “in situ” demonstration experiments and their instrumentation are described. The first test (FEBEX Experiment)
involves the hydration of a compacted bentonite barrier under the combined effect of an inner source of heat and an outer
water flow from the confining saturated granite rock. In the second case, the progressive de-saturation of Opalinus clay induced
by maintained ventilation of an unlined tunnel is analyzed. The paper shows the performance of different sensors (capacitive
cells, psychrometers, TDR’s) and a comparison of fill behaviour with modelling results. The long term performance of some
instruments could also be evaluated specially in the case of FEBEX test. Capacitive sensors provide relative humidity data
during long transient periods characterised by very large variations of suction within the bentonite. 相似文献
143.
BTOPMC模型与新安江模型在史河上游的应用比较研究 总被引:1,自引:0,他引:1
介绍了一个由TOPMODEL发展而来的基于栅格的分布式水文模型--BTOPMC模型.选取史河流域黄泥庄水文站以上集水面积为研究区域,在空间分辨率为30秒的数字高程模型数据基础上构建数字流域水系,基于IGBP全球陆面土地覆被数据以及FAO全球数字土壤数据运用BTOPMC模型和新安江模型分别对黄泥庄站1982年到1987年的日径流过程进行模拟.采用模拟与实测洪量比和确定性系数对两个模型的模拟结果进行比较分析.结果表明两个模型都能很好地模拟日径流过程,新安江模型有更好的模拟效果. 相似文献
144.
Fayun Liang Mingyi Zhao Chengrui Qin Yajie Jia Zhongwei Wang Guiping Yue 《Marine Georesources & Geotechnology》2020,38(1):114-121
AbstractThe construction of a 100-km road network is planned on a land reclamation area in the Oujiang Estuary in China. The embankment had a height of 4 m and a base width of 60 m. The reclamation area is newly filled by a 3-m dredger fill on a 48-m thick layer of marine clay. Estimation of the settlement of the future road network is difficult. To guide the construction of the road network, a 1/100-scale centrifuge model test was performed with a marine clay sample from the construction site to simulate the layered settlements and evaluate the drainage effect of prefabricated vertical drains in the dredger fill in the following 10 years. The results of the centrifuge modeling test are verified by 10-month in situ monitoring, which shows agreement between the centrifuge modeling test results and the in situ results. The test results indicate that additional time is needed to reinforce the newly added dredger fill by the surcharge preloading method to uplift the elevation of the reclamation area with dredger fill. 相似文献
145.
Tiago M. Alves Vasilios Lykousis Dimitris Sakellariou Stamatina Alexandri Paraskevi Nomikou 《Geo-Marine Letters》2007,27(1):41-61
Bathymetric, 9.5-kHz long-range sidescan sonar (OKEAN), seismic reflection and sediment-core data are used in the analysis
of two tectonic troughs south of Crete, Eastern Mediterranean Sea. Here, up to 1.2 s two-way travel time (TWTT) of strata
have accumulated since the Middle Miocene in association with extension in the South Aegean region. The study area comprises
>100-km- long by >25-km-wide basins filled by sediments subdivided into two seismic units: (1) an upper Unit 1 deposited in
sub-basins which follow the present-day configuration of the southern Cretan margin; (2) a basal Unit 2, more than 500 ms
(TWTT) thick, accumulated in deeper half-graben/grabens distinct from the present-day depocentres. Both units overlap a locally
stratified Unit 3 comprising the pre-Neogene core complex of Crete and Gavdos. In this work, the interpreted seismic units
are correlated with the onshore stratigraphy, demonstrating that denudation processes occurring on Crete and Gavdos in response
to major tectonic events have been responsible for high sedimentation rates along the proximal southern Cretan margin. Consequently,
topographically confined sedimentary units have been deposited south of Crete in the last 12 Ma, including turbidites and
other mass-flow deposits fed by evolving transverse and axial channel systems. Surface processes controlling facies distribution
include the direct inflow of sediment from alluvial-fan systems and incising mountain rivers onto the Cretan slope, where
significant sediment instability processes occur at present. In this setting, seismic profiles reveal eight different types
of stratigraphic contacts on basin-margin highs, and basinal areas show evidence of halokinesis and/or fluid escape. The acquired
data also show that significant changes to the margin’s configuration occurred in association with the post-Alpine tectonic
and eustatic episodes affecting the Eastern Mediterranean. 相似文献
146.
147.
148.
秦勃 《中国海洋大学学报(自然科学版)》1997,(4)
给出一种树型网络拓扑的语义描述方法及其拓扑简图的生成算法。该方法通过建立网络联接线路标识串集和网络设备连接标识串集,来构造网络设备的拓扑描述,并计算生成网络拓扑简图。 相似文献
149.
Noriaki Kimura 《Journal of Oceanography》2007,63(4):685-694
This paper examines the mechanism controlling the short time-scale variation of sea ice cover over the Southern Ocean. Sea
ice concentration and ice velocity datasets derived from images of the Defense Meteorological Satellite Program (DMSP) Special
Sensor Microwave Imager (SSM/I) are employed to reveal this mechanism. The contribution of both dynamic and thermodynamic
processes to the change in ice edge location is examined by comparing the meridional velocity of ice edge displacement and
sea ice drift. In the winter expansion phase, the thermodynamic process of new ice production off the ice edge plays an important
role in daily advances of ice cover, whereas daily retreats are mostly due to southward ice drift. On the other hand, both
advance and retreat of ice edges in the spring contraction phase are mostly caused by the dynamic process of the ice drift.
Based on the above mechanism and the linear relation between the degree of ice production at the ice edge and northward wind
speed, the seasonal advance of ice cover can be roughly reproduced using the meridional velocity of ice drift at the ice edge. 相似文献
150.
Two distinct series of slumps deform the upper part of the sedimentary sequence along the continental margin of the Levant.
One series is found along the base of the continental slope, where it overlies the disrupted eastern edge of the Messinian
evaporites. The second series of slumps transects the continental margin from the shelf break to the Levant Basin. It seemed
that the two series were triggered by two unrelated, though contemporaneous, processes. The shore-parallel slumps were initiated
by basinwards flow of the Messinian salt, that carried along the overlying Plio-Quaternary sediments. Seawater that percolated
along the detachment faults dissolved the underlying salt to form distinctly disrupted structures. The slope-normal slumps
are located on top of large canyons that cut into the pre-Messinian sedimentary rocks. A layer of salt is found in the canyons,
and the Plio-Quaternary sediments were deposited on that layer. The slumps are bounded by large, NW-trending faults where
post-Messinian faulted offset was measured. We presume that the flow of the salt in the canyons also drives the slope-normal
slumps. Thus thin-skinned halokynetic processes generated the composite post-Tortonian structural patterns of the Levant margin.
The Phoenician Structures are a prime example of the collapse of a distal continental margin due to the dissolution of a massive
salt layer. 相似文献