Research on the Techniques of Slope Stability through an introduction of suction

晴天天然边坡存在负孔隙水压力(吸力)，对边坡稳定有一定的作用。在雨天，孔隙水压力上升到正值，可能会失去边坡的稳定性。如果在边坡中埋设土工织物或毛细管膜排水管，即使在雨天也能保持边坡的负孔隙水压力，保持边坡的稳定性。土工布的毛细张力应大于1米水头。根据测试结果，目前还没有直接适用的材料。然而，如果将几种土工织物压缩在一起，得到一种高密度的新土工织物，问题就会得到解决。为了保持织物末端的干燥，有必要用一张薄片覆盖坡面。当真空压力施加在板材背面时，坡面受到大气压力的挤压，边坡稳定性增加。三轴试验表明，由于真空压力的固结和非饱和条件的出现，土体的强度有所提高。强度增强率达10%。为了将真空压力引入边坡，有必要布置土工布。

The negative porewater pressure (suction)exists in the natural slopes in fine day and contributes to the slope stability. In rainy days, the porewater pressure rises to the positive values and the stability of the slope may be lost. If the geo-textiles or the drainpipes with capillary membrane are embeded, negative porewater pressure may remain in the slope even on rainy days and stability of the slope can be kept. The geo-textile should have capillary tension more than 1m waterhead. According to the test results, there are no applicable materials directly. However, if a few geo-textiles are compressed together and a new geo-textile having high density is obtained, the problem will be solved. It is necessary to cover the slope surface by a sheet in order to keep the textile-end dry. When vacuum pressure applies to the backside of the sheet, slope surface is pressed by the atmospheric pressure and slope stability increase. Moreover, the soils of the slope may change to unsaturated condition.According to the triaxial tests, the strength of the soils increases due to consolidation of vaccum pressure and due to occurrence of unsaturated condition. Strength increase ratio reaches to 10%. It is necessary to arrange the geotextiles in order to introduce vacuum pressure into the slope.