Analysis And Improvement Of Classical Slope Stability Methods In Seepage Soil Mass

It is quite chaos when it comes to slope stability analysis in seepage soil mass in slope engineering management. The influence of seepage on stability of soil slope should be considered properly. It is pore water pressure around the soil mass not seepage force should be taken into account when the subject is the mixture of soil and water and vice versa when the subject is soil skeleton. The pore water pressure should be in balance with the soil saturated weight and the seepage force should be in balance with the soil buoyant weight. In slope stability analysis, the issue may be simplified as a seepage force instead of pore water pressure around the soil mass.Equivalence of separate calculation of water and soil pressure and combining calculation of water and soil pressure is demonstrated. Taking the macroscopic soil slice and microscopic seepage flow net unit as the study objects, the pore water pressure around the soil mass or seepage flow net unit can be arrived in the principle of the pressure head are the same in an equipotential line. After rigorous mechanical analysis, it is proved that resultant force of water weight and pore water pressure around the soil is same with seepage force in magnitude, direction and acting position. It is demonstrated that pore water pressure should be in balance with the soil saturated weight and the seepage force should be in balance with the soil buoyant weight.Clarified the distinction between pore water pressure around the soil mass and seepage force in analysis and improvement of Fellenius method, simplified Bishop method and Janbu method. The relationship between the border forcer and volume force is handled correctly. The force of pore water pressure and weight of soil mass are matched properly. The pore water pressure on the side of soil trips is determined by the characteristics of flow net and then the pore water pressure on the side and slip surface can be obtained.The analysis of classical slope stability method reveals the mechanism of action of seepage. The formula of safety factor in seepage soil mass for simplified Bishop method is arrived after the mechanical analysis and mathematical calculation. Compared with the safety factor formulas of the two study subjects which one is the mixture of soil and water and the other is soil skeleton, the same results are gained and the phenomenon indicates that the two methods are the same in essence.Calculation program in Fortran language for classical slope stability method in seepage soil mass is programmed. The methods mentioned above are proved to be reliable because the safety factors of the methods are consistent with authoritative conclusions. In addition, this paper has analyzed the existed methods for slope stability in seepage soil mass and points out the deficiencies or errors of these methods.