动水压力下隧道衬砌水压演变规律及防排水优化研究OA

In order to explore the evolution law of water pressure behind the tunnel lining during the surface strong rainfall,and optimize the existing drainage scheme,a set of seepage model test system was built,and the evolution law of water pressure of the lining under the schemes of half covering and half draining and the bottom falling of the central drainage ditch was experimentally studied.A numerical model was further established to compare and analyze the drainage effects of three schemes,namely,half wrapped and half drained,circular drainage pipe densification and central drainage ditch bottom falling,and the optimal scheme for water-rich tunnels was selected.The results show that:under the scheme of half covering and half draining,the water pressure of tunnel lining increases with the increase of water head,the inverted arch water pressure cannot be effectively reduced through the drainage system,and the water pressure distribution is"mushroom"with small arch and large inverted arch.Under the circular drainage pipe densification scheme,the water pressure in the tunnel arch wall area is significantly reduced,but the inverted arch area still maintains high water pressure,which further degrades the stress of the inverted arch structure.Under the scheme of the central drainage ditch falling to the bottom,the water pressure in the arch and invert areas of the tunnel is greatly reduced,the water head of the lining resisting at the critical state of safety and failure is 105m and 253m respectively.The water pressure resistance capacity is 5(7.6)times of the scheme of half covering and half draining.In the structural design of water-rich mountain tunnel,it is suggested to adopt the drainage structure type of central drainage ditch falling to the bottom.