一、隧道开挖模拟基本方法由于城市铁路隧道一般接近地表,岩土体结构相对松散,构造应力常常可以忽略不计,初始应力场可以假定为重力场。当用有限单元法模拟在自重作用下隧道的开挖效果时,一般采用反转应力释放法和空单元法进行计算。隧道开挖前围岩处于初始应力状态{σ}o,以及与之 First, the basic method of tunnel excavation simulation Urban rail tunnels generally close to the surface, rock and soil structure is relatively loose, tectonic stress can often be neglected, the initial stress field can be assumed to be gravity field. When using the finite element method to simulate the tunnel excavation effect under the self-weight effect, the method of inverse stress release and the empty element method are generally used to calculate. Before tunnel excavation, the surrounding rock is in the initial state of stress {σ} o, and with it