Abstract: Excessive settlement deformation problem in highway tunnel construction is frequently encountered when it passes through the silty clay soils. This paper evaluates potential factors that might induce the excessive deformations in the highway tunnel excavation in the silty clay soils. Deformation control measures are also summarized. The results of construction of Wangjiashan Tunnel in Chizhou are presented as a background. The monitoring data of ground subsidence, settlement at the crest as well as the side of the tunnel are compared and analyzed so that the stress and strain characteristics of the tunnel could be obtained. Based on the analytical information, different tunnel excavation induced settlement control measures could be implemented in both left and right tunnel excavations. The results show that there was a synchronous change relationship between the surface settlement and the settlement deformation during the tunnel excavation in silty clay soils; the foundation grouting reinforcement program could, not only rapidly and effectively reduce the surface settlement and the deformation in the tunnel, but also shorten the stability time of the settlement deformation. The control effect of the settlement deformation in the tunnel excavation is better than that of the filling replacement measure. 

Key words: silty clay soils, highway tunnel, monitoring and measurement, deformation