The Infiltration Numerical Simulation for Several Kinds of Unsaturated Soil under Rainfall Condition - Advanced Research on Computer Education, Simulation and Modeling - page 243

The Infiltration Numerical Simulation for Several Kinds
of Unsaturated Soil under Rainfall Condition
Dongfang Tian
College of Hydraulic & Environmental Engineering, China Three Gorges University
Yichang, Hubei 443002, China
[e-mail]
Abstract. The research of infiltration numerical simulation for unsaturated soil
is of great significance in the fields such as soil science, hydrology and water
resources etc. In this paper, based on the numerical couple model of infiltration
and runoff, the infiltration processes of silt, silt clay and clay column are simu-
lated. The couple model is based on Richards' equation and kinematic wave
model. The calculation results show that the infiltration in clay soil is most slow
and wetting front is sharpest. This paper has some guiding significance to the
research of infiltration process.
Keywords: rainfall, unsaturated soil, infiltration, numerical simulation.
1 Introduction
The stability problem of rock and soil engineering caused by rainfall is very important
in literature. The key to solve the problem is to deepen the evolution of the state,
moisture and water potential of unsaturated soil during infiltration processes under
rainfall condition [1]. The infiltration processes contains two stages [2]: one is free
seepage, another is pressure infiltration. In free seepage stage, the surface soil is dry;
the infiltration rate is lager than rainfall intensity, all the rainfall infiltrates into soil.
While in pressure infiltration stage, surface soil is saturated, and the infiltration rate is
close to the saturated conductivity of soil.
With the rapid development of Computer Technology and algorithm, many nu-
merical methods are brought out to simulate the seepage of unsaturated soil under
rainfall condition. A representative numerical model is the couple model of infiltra-
tion and runoff [3]. The couple model is based on Richards' equation and kinematic
wave model. Furthermore, the couple model could solve the seepage and runoff si-
multaneously.
In order to seek for the evolution of infiltration processes, four kinds of soils such
as silt, silt clay and clay are simulated in this paper. The soil-water characteristic
curves of four soils are Fredlund model. Based on the couple model, the infiltration
processes of different soils under rainfall condition are compared.