Abstract: Restricting the heave of underlying tunnels is crucial to the construction control of excavations, as pit excavations will cause structure deformation of tunnels in the excavation engineering on existing tunnels. This paper detailedly introduces the characteristics of excavations above existing tunnels, including the crossing directions, tunnel deformation modes, and common controlling measures. 39 similar projects recently constructed in China are categorized and analyzed. Based on the influence of every factor on maximum tunnel heave in longitudinal direction, a model is established to predict the tunnel heave. The results show that the engineering geology conditions have a greater influence on the tunnel deformation in such projects. The worse the engineering geology conditions are, the harder the controlling of tunnel heave will. The other important factors of the tunnel deformation are excavation depth, pit area and shapes of excavations. The tunnel deformation will increase with the excavation depth and pit area. The more irregular of the foundation pit, the harder the controlling of tunnel heave. In soft clay area uplift piles can effectively reduce the maximum deformation of tunnels in the large and deep excavation engineering.

Key words: excavation, underlying existing tunnels, heave deformation, prediction model