Abstract: To study three-dimensional spatial variation of stress field for layered jointed rock tunnel，a calculation model was established under different partitions according to the on-site joint statistics.And the entire process of tunnel excavation step was simulated by three-dimensional discrete element method.The result showes that when the tunnel face approaches to and passes through a cross section，the influence area of the tunnel section on spatial principal stress and plane stress，was about  2.0 B（B-span length）.

Key words: Layered jointed, Tunnel, Stress field, Numerical simulation, Discrete element