Stability Evaluation Of Saturated-Unsaturated Fractured Porous Rock Slope Under The Influence Of Rainfall

At first, the hydraulic character of unsaturated fractured porous rock is explicated in this paper, and the moisture rate-capillary pressure relation function, which is fitted with the known model, is deduced based on capillary theory. Based on these, as the project of beijige slope an example, the numerical modeling of saturated-unsaturated seepage in diversified rainfall condition is studied. Then by applying the un-linear programming method, the critical glide surface of the slope is searched. At last, the stability of slope is evaluated by using the limit equilibrium method which are established on the unsaturated soil mechanics.The water retention curves of some kinds of infiltrative rock masses which grow a great deal of capillary have been applied in some research. But to get the water retention curve for fractured porous rock exactly by experiment is still very difficult. Based on the microstructure character, which is derived from microstructure experiment of rock, and the capillary theory, the predicting method of water retention curve for fractured porous rock is discussed and applied to the instance analyzing.Contraposing this kind of rock slope, the medium models for unsaturated seepage are discussed and the most appropriate model is selected. Then the known Gardner model, Brooks-Corey model and van Genuchten model are adopted to fitting the computed unsaturated permeability coefficient data, and the best model is selected. Based on these, the numerical modeling of unsaturated seepage in different rainfall condition, such as different rainfall intensity and duration, is studied. The result indicates that rainfall can evidently influence the pore water pressure in the slope body.Contraposing this slope instance, the likely destroyed mode is analyzed and a procedure for searching the critical glide surface of slope based on un-linear programming method is designed.After the numerical modeling of unsaturated seepage and the critical glide surface searching, the slope stability in different rainfall conditions is evaluated by using the GLE method and the Bishop method which are established on the unsaturated soil mechanics. With the calculating result, the rule of the stability coefficient changing with the rainfall intensity and duration is analyzed. This can provide dependable theory basis for the slope stability evaluation in the rainfall condition.