A Study On Seepage Field And The Coupling Of Stress Field And Seepage Field And Its Application

The unsaturated seepage problem, the optimization of seepage control measure to dykes and the interaction and coupling between seepage field and stress field are the importance problems in geotechnical engineering. The unsaturated seepage problem is one of the important studies of the unsaturated soil mechanics. Many unsaturated soil mechanics are related with the transient seepage of unsaturated soil under the flux-boundary. Considering the theory problem and engineering appliance, it is very significative for us to make a systematic study. Because there are many riverway-dyke projects, whose breakage reasons mostly ascribe to the seepage, it is necessary to research the seepage-control case and optimization. Seepage field and stress field are the most important composing-parts of geotechnical engineering mechanics. The interaction between seepage field and stress field of rock and soil medium embody the coupling relation between two fields. Considering two fields as a system, it is also essential to research and discuss the coupling problem between seepage field and stress field.Being based upon summarizing the existing research, this thesis mostly covers the Finite-Element Modeling of the saturated-unsaturated and steady-unsteady seepage, the compare and optimization of dykes-seepage measure, soil slaking and its displacement-calculation, the interaction and coupling between seepage field and stress field.1. This thesis first introduces soil moisture potential theory, then research and discuss the basic unsaturated seepage theory, the relation of soil-water's characteristic curve and seepage coefficient and the confirmation of the material unsaturated seepage coefficient.2. Beginning basic seepage theory, thesis introduce the 3D saturated-unsaturated and steady-unsteady seepage differential equation of porous media and the FEM regarding pressure water head as basic unknown quantity. On the saturated-unsaturated seepage field FEM, both the seepage in the saturated area and the hydrodynamic effect in the unsaturated area are considered, unifying saturated-unsaturated seepage field andapplying uniform derivative governing equations in the wholly seepage field.3. Applying the 3D saturated-unsaturated FEM program and calculating one project instance, the change of the seepage when water head rises and descend also are researched and discussed. That shows that with the water head rising, negative pressure area reduces, pore water pressure in saturation area enlarges, partly soil changes from unsaturated status to saturated status and the area matric suction loses or minishs. During the water head rises, zero pore water pressure-line rises lagging hysteresis effect comparing to the rise of water head, pore water pressure isoline becomes abrupt on the local region, the grads of pore water pressure in local area are marked and waterpower slope-drop enlarges. Moreover, pore water pressure-isoline becomes evidently denseness in local negative pressure area. The more rapidly the water head rises and the smaller the seepage coefficient is, the more evident the lag is. The rise of the upriver water head has little effect on the midland close to backward position of the dam. Upriver dam has seepage along the slope. The more rapidly the water head descend and the smaller the seepage coefficient is, the more evidence the lag and seepage along the slope are, and the greater the waterpower slope-drop at the upriver dam slope is, correspond to which the greater the seepage hydrodynamic pressure along the dam slope and the more the seepage-steady in the dam is affected badly.4. Dyke seepage control, upright defence seepage and horizontal defence seepage are introduced. The style and the specialty of the dyke foundation are analyzed. The anisotropism of the penetrability in soil layer and the effect of the thickness of surface overcast low penetrability layer are researched. Anisotropism of the penetrability of dam and foundation material arouses that the density of the equipotential line of water head at entrance en...