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171.
金沙江某水电站库区泥石流地质灾害研究 总被引:1,自引:0,他引:1
李进元 《中国地质灾害与防治学报》2003,14(3):44-49
金沙江是我国水能资源最为丰富的江河之一,但在金沙江上修建水库,泥石流是经常遇到的地质灾害问题。文章在详细调查了库区地层岩性、构造、滑坡的前提下,结合金沙江某水库区泥石流发育与降雨、地层岩性、构造、滑坡及地形地貌的关系深入探讨了库区泥石流的类型、规模、特征及发育阶段。研究表明:(1)本库区泥石流活动历史久远,泥石流地质灾害活跃,在部分泥石流地质灾害衰退的同时,更多的泥石流沟在逐步形成:(2)水库蓄水,减小了泥石流沟的比降,会在一定程度上降低泥石流的活动性及破坏能力;(3)泥石流对水库的影响主要为输送泥沙,造成水库淤积。 相似文献
172.
冯俊录 《中国地质灾害与防治学报》2003,14(3):136-137,141
北碚醪糟坪泥石流防治工程,在施工中使用了多工艺方法,泥石流前缘采用桩、粱、锚支挡工程,相互连接及帷幕灌浆,改变土质性能,加强稳定性,泥石流中段大胆采用碎石毛石重力坝,阻拦上部泥石流,加上盲沟连接碎石桩和重力坎,排泄地下水、地表水。为了防止泥石流上段北岸继续造成滑塌,在北岸进行护坡桩保护。后缘是根据彻底根治原则,用人工挖孔抗滑桩,桩上端与横粱相连,粱与锚桩连接,切断了泥石流物质来源。该泥石流是地表水和地下水不畅通而引起的,在泥石流中下部修建了盲沟网格,明渠修建在下部外围稳定的土体上,水渠沟沟相通,最后集中排泄到明渠中流走。该泥石流采用综合整治方法,大胆使用碎石桩毛石重力坎,这一工艺获得了理想效果。 相似文献
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The three-dimensional flow field in a scour hole around different abutments under a clear water regime was experimentally measured in a laboratory flume, using the Acoustic Doppler Velocimeter (ADV). Three types of abutments used in the experiments were vertical-wall (rectangular section), 45° wing-wall (45° polygonal section) and semicircular. The three-dimensional time-averaged velocity components were detected at different vertical planes for vertical-wall abutment and azimuthal planes for wing-wall and semicircular abutments. The velocity components were also measured at different horizontal planes. In the upstream, presentations of flow field through vector plots at vertical / azimuthal and horizontal planes show the existence of a primary vortex associated with the downflow inside the scour hole. On the other hand, in the downstream, the flow field shows a reversed flow near the abutments having a subsequent recovery with a passage of flow as a part of the main flow. The data presented in this p 相似文献
177.
Calvin W. Rose Bofu Yu William L. Hogarth Augustine E. A. Okom Hossein Ghadiri 《Journal of Hydrology》2003,280(1-4):33-51
The spatial and size distribution of sediment deposited from short periods of overland flow due to the effect of a simulated grass buffer strip was measured for low slopes of 1.6, 3.4 and 5.1%. These data were analysed so as to critically evaluate two alternative models of the process of re-entrainment of recently deposited sediment. A model of re-entrainment, previously thought to be appropriate only for a steady-state or equilibrium situation, was found to give better agreement with experiments than did a model previously used in the literature on this subject. 相似文献
178.
David A. DiCarlo 《Advances in water resources》2003,26(12):1257-1266
After the initiation of gravity drainage, water is often assumed to be either (a) draining under unit gradient, or (b) at capillary/gravity equilibrium. Both of these simplifications can be useful, but the regimes of validity of each assumption must be delineated. Water pressures are measured versus time and distance as water drains out of a 1.6 m long sand column to determine the relative effects of capillary and gravitational forces during drainage. For medium sized sands (0.15–0.3 mm in diameter), the capillary pressure is constant in space in a large region of the column for over 12 days, and the water continues to flow under unit gradient for relatively long time scales. Similar results are seen for finer sands, but with a much faster approach to equilibrium. Numerical simulations and analytical estimates are presented and compare favorably to the measurements. Together, the experimental, theoretical and analytical results are used to calculate when capillary/gravity equilibrium is reached as a function of porous media properties and length of the unsaturated zone. The ratio of the length of the unsaturated zone to the bubbling pressure is a key parameter in determining the drainage regime, and that even for relatively short unsaturated zones the equilibrium time scale can be on the order of years. 相似文献
179.
We present results of laboratory experiments to study the behavior of liquids moving in unsaturated wide-aperture fractures. A 5-mm-thick glass plate cut with a 1.7-mm aperture was used as a fractured rock analog to study behavior of film and capillary droplet flow modes. Flow rates ranged between 0.6 and 6.0 ml/min. Variability in the ambient barometric pressure, resulting from weather conditions, seemed to play a role in the natural selection of flow mode. For droplet mode, constant input conditions resulted in highly variable transport properties within the fracture. The advancing meniscus exhibited a dynamic contact angle that was a function of the droplet speed and much larger than the static contact angle. Flow rate was reduced due to the larger contact angle. Analytical expressions for droplet velocity and flow capacity are presented as a function of the dynamic rather than the static contact angle. 相似文献
180.
A Laplace-transform analytic element method (LT-AEM) is described for the solution of transient flow problems in porous media. Following Laplace transformation of the original flow problem, the analytic element method (AEM) is used to solve the resultant time-independent modified Helmholtz equation, and the solution is inverted numerically back into the time domain. The solution is entirely general, retaining the mathematical elegance and computational efficiency of the AEM while being amenable to parallel computation. It is especially well suited for problems in which a solution is required at a limited number of points in space–time, and for problems involving materials with sharply contrasting hydraulic properties. We illustrate the LT-AEM on transient flow through a uniform confined aquifer with a circular inclusion of contrasting hydraulic conductivity and specific storage. Our results compare well with published analytical solutions in the special case of radial flow. 相似文献