STUDY ON STEADY STATE PHREATIC SURFACES OF HOMOGENEOUS SOIL OVERLYING IRREGULAR IMPERVIOUS GEOLOGICAL INTERFACE

Abstract

The distribution of groundwater has a significant impact on the stability and treatment of slopes(landslides), and there are many influencing factors. At present, there are no analytical formula for the steady state phreatic surfaces of homogeneous soil overlying irregular impervious geological interface, especially knowing that the slope(landslide) body has a known water level, accurately determining the infiltration line of the slope body between the known water levels plays an important role in evaluating the stability of the slope(landslide).Therefore, It is necessary to study the steady state phreatic surfaces of homogeneous soil overlying irregular impervious geological interface. Based on the simplification of free surface flow, this paper deduces the expression of groundwater single-width aquifer flow of homogeneous soil on the bed with a certain slope(impermeable). According to the bed inclination angle, the expression of homogeneous aquifer flow(Boussinesq equation) is divided into two kinds of expressions(downstream slope and reverse slope). According to two Boussinesq equations and the principle of fluid continuity, the steady seepage analytical formula of phreatic surfaces and the flow of homogeneous soil overlying irregular impervious geological interface are obtained. By comparing with the results of numerical simulation(Autobank finite element program),it can be seen that the analytical solution in this paper is basically consistent with the phreatic surfaces and the flow rate of finite element numerical simulation(Autobank finite element program). Due to the use of the Dupuit approximation, there is a certain error between the analytical solution and the numerical solution. The error along the slope is greater than that of the reverse slope, and the larger error of the slope is larger than that of the smaller slope. Fortunately, the error caused by the approximation is very small. Generally speaking, the analytical method of the steady-state phreatic surfaces is reliable, stable and logical.