Lateral damage mechanism of the double-track tunnel in the mountainous layered soft rock and NPR anchor cable control

Due to complex geological formations,lateral damage often occurs during excavation in mountainous layered soft rock double-track tunnels.This paper discusses the stresses and the damage characteristics of the surrounding rock under overload in a mountainous layered soft rock double-track tunnel through indoor model experiments to provide a basis for the effective control of lateral damage.The experiments show that the conventional support method cannot effectively control the lateral damage due to interlayer sliding.Therefore,the negative Poisson’s ratio(NPR)anchor/cable control method is proposed.And the scientificity and feasibility of the NPR anchor/cable control technology are proved by the field application and monitoring data of the Minxian Tunnel and Changning Tunnel.It is further demonstrated that high preload is the most effective way to control the lateral damage in layered soft rock tunnels.