發送短信 : Stability analysis of underground excavation

 _    _    _    _    _    _     _____    __   _   
| |  | || | || | || | |  | ||  |  ___|| | || | || 
| |/\| || | || | || | |/\| ||  | ||__   | '--' || 
|  /\  || | \\_/ || |  /\  ||  | ||__   | .--. || 
|_// \_||  \____//  |_// \_||  |_____|| |_|| |_|| 
`-`   `-`   `---`   `-`   `-`  `-----`  `-`  `-`