The Research Of The Effect Of Soil-Water Characteristic On The Slope's Seepage And Safety

The analysis of the slope stability has aways been a difficult problem, for the involving factors are various and the failing mechanism is complicate.To solve this problem, this paper discussed the behave of this matter under the effect of the soil-water characteristic curve(SWCC). The soil-water characteristic curve directly affects the seepage of the dam so that affects the dam slopes' safey factors. However, the SWCC hasn't been used in practical engineering; The suction friction angle is used to discrible the effect of suction on the soil's shear strength. Bacause the suction friction angel is increasing while the water content is increasing, so it is very difficult to obtain an accurate suction friction angle. For this, the suction friction angel hasn't been considered in practical engineering. While the concrete cut-off wall is cheap and easy to construct with a good anti-seepage effect, the depth of it is exceeding one hundred meters in nation. But the depth optimizing research of the concrete cut-off wall haven't been mature. Aimed at the above three aspects, the paper was constituted of the following contents:(1) Discussed the problem of opting the waterback side slope's boundary condition and the left and right boundary condition in the Seepage block of Geo-studio, and the problem of opting the reasonable Siegel grid density and tangent density. Educed a reasonable water-back-side and left and right boundary condition, and a reasonable Siegel grid density and tangent density(2) Discussed the effect of concrete cut-off wall on the dam's seepage, critical points' hydraulic gradient and the water back-side slope's safety factor, providing a reference for the optimizing of the concrete cut-off wall.(3) Discussed the water-move-toward slope's safety factor variating routine while the water level rising. Researched the effect of the different shape of the adsorption SWCC and the water level rising rate on the water-move-toward slope's and water back-side slope's safety factors.(4) Discussed the water-move-toward and water back-side slope's safety factor variating routine while the water level dropping. Researched the effect of the different shape of desorption SWCC and water level dropping rate on the water-move-toward slope's and water back-side slope's safety factors.(5) In one water level rising and dropping cycle, the water-move-toward slope's safety factor variating line intersects forming two ring; the water back-side slope's safety factor changing curve intersects forming one ring. Mirroring the water-move-toward slope safety factor changing curve's right cycle with a mirror constituting with the two lowest points on the safety factor changing curve and integrating the mirror inage with the middle big cycle, a whole hysterisis cycle can be formed. The whole hysterisis cycle is alike the water back-side's hysterisis cycle. This phenomenon reflects the extent of the effect of the hydraulic pressure on the slope surface and the pore pressure's insteading each other;(6) The computing results of the finite element combining limit equilibrium consistent with strength reducing method of Mhor-Cloumb equilivent circle yielding criterion Then this method was used to analysis the effect of suction friction angle on the unsaturated slope safety factor.