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Behavior of pore water pressure and stability evaluation against seepage failure in earth slopes

土质边坡孔隙水压力特性及渗流破坏稳定性评价

基本信息

批准号：
15560432
负责人：
NARITA Kunitomo
金额：
$ 0.77万
依托单位：
Aichi Institute of Technology (A.I.T.)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560432/
关键词：
Centrifuge Model Test Rapid Draw-down Pore Water Pressure Seepage Failure Slope Failure Saturate Unsaturated Seepage Seepage by Rainfall Slope Protection

项目摘要

In order to study behavior of the residual pore-water pressure and its influence on slope stability in earth dams during a rapid draw-down of the reservoir water, centrifuge model tests were conducted on several model fills by realizing draw-down of the upstream water level under a constant centrifuge acceleration, in which small size transducers were installed in matrix for pore-water pressure measurement. Several different conditions to be supposed were set in the experiment to investigate influential factors on accumulation of the built-up pore-water pressure in embankments : that is, the case where the rate of draw-down is changed for the same type homogeneous embankments, the case where a thin impervious soil layer is set on the upstream face as an inclined core zone, and the case where a L-type drain is set to promote dissipation of pore-water pressure in the middle part of an embankment. Some failure tests, in which sliding failure is reproduced in the upstream slope, were also … More conducted to discuss instability of slopes caused by the increase of the residual pore-water pressure built up during draw-down. Concluding remarks drawn from the present study are summarized as follows : (1) In the case where the rate of draw-down of the reservoir water is high, drainage water from the interior to the up stream face is restricted even in a homogeneous dam, and the residual pore-water pressure develops in the upstream slope to have a large influence in slope stability. (2) In a dam with a thick impervious core zone, a discontinuous head difference appears in every state between the reservoir water level and the phreatic surface in the dam, due to little flow of drainage water to the upstream face. (3) Although the residual pore-water pressure reduces rapidly in the interior of an embankment by setting a L-type drain, it still shows high value in the surface part of the fill to the extent of the case without drainage facilities, and comparatively deep sliding failure passing through the crest appeared as the water level decreases.Another series of centrifuge tests were done on the behavior of seepage uplift pore-water pressure acting on the base of a river dyke resting on a permeable soil foundation, and discussion was made on the influence of the uplift pressure on such seepage failures of embankment as piping and loss of bearing capacity. Analytical studies were also performed by use of the FEM saturated and unsaturated seepage analysis, and a method of stability evaluation of earth slopes was proposed, by taking into account of distribution of pore-water pressure along a sliding plane and that of hydraulic gradient in the fill, from both view points of sliding failure due to pore-water pressure and seepage failure (hydraulic fracture) due to concentration of hydraulic gradient. Less

为了研究库水快速下降过程中土坝残余孔隙水压力的变化规律及其对坝坡稳定性的影响，通过在土坝模型上安装小型孔隙水压力传感器，实现上游水位在恒定离心加速度下的下降，对几种土坝模型进行了离心模型试验。试验中设置了几种不同的假设条件，考察了影响固结土中孔隙水压力累积的因素：也就是说，对于同一类型的均质填料，改变下降速率的情况，在上游面设置薄的不透水土层作为倾斜芯区的情况，以及设置L型排水管以促进路堤中部孔隙水压力消散的情况。一些破坏试验，其中滑动破坏再现在上游边坡， ...更多信息讨论了在水位下降过程中，由于残余孔隙水压力的增加而引起的边坡失稳问题。（1）在库水下降速度快的情况下，即使在均质坝中，从坝内向上游面的排水也受到限制，残余孔隙水压力在上游边坡中发展，对边坡稳定性影响很大。(2)在厚防渗心墙坝中，由于上游面排水量小，库水位与坝内潜水面之间在各种状态下均出现不连续的水头差。(3)设置L型排水沟后，路堤内部的残余孔隙水压力虽然迅速降低，但在不设置排水设施的情况下，填土表层的残余孔隙水压力仍然很高，在此基础上，通过离心试验，研究了渗流-抬升孔隙水动力特性，并对渗流-抬升孔隙水动力特性进行了分析。摘要对作用在透水性地基上的河堤堤基上的水压力进行了分析，并讨论了扬压力对堤基管涌、承载力损失等渗透破坏的影响。利用有限元饱和和非饱和渗流分析进行了分析研究，提出了一种考虑孔隙水压力沿着滑动面的分布和填土中水力梯度的分布，从孔隙水压力引起的滑动破坏和水力梯度集中引起的渗透破坏（水力破裂）两个角度评价土坡稳定性的方法。少