A three-dimensional numerical method for siphon drainage process simulation

Siphon drainage using inclined borehole and 4 mm inner diameter pipes is an efficient and stable measure for long-term landslide drainage. In order to compare alternative drainage arrangements more efficiently, a numerical method is proposed for siphon drainage process simulation. The novelty of this method is to simulate the dynamic process of siphon drainage by a series of iterative seepage analyses. The whole drainage process is divided into many small time steps and each one corresponds to an independent seepage analysis. The iterative operation is fully automated by reading and rewriting the calculation document with Python code. The siphon flow rate in each analysis is determined by the total head at the siphon pipe inlet obtained from the previous analysis result. An empirical formula based on experimental data is used for flow rate calculation. SEEP3D is adopted to perform the three-dimensional seepage analysis. BUILD3D along with computer-aided design software is used to build the three-dimensional model with a realistic topographic surface. The proposed method is illustrated and validated with a case, the Shaqiucun landslide, China. A parameter study is carried out and the influence of parameter setting on the drainage effect is discussed.